Principles of Neurosurgery - Grossman R.G., Hamilton W.J.

Author: Grossman R.G. Hamilton W.J.

Tags: medicine surgery

ISBN: 0-88167-750-7

Year: 1991

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Text

Principles of
eurosurger
.EDITOR
Robert G. Grossman, M.D.
Department ofNeurosurgery
Baylor College of Medicine
Houston, Terias
ASSOCIATE EDITOR
Winifred J. Hamilton, Ph.D.
Department ofNeurosurgery
Baylor College of Medicine
Houston, Texas
C0nsultingEditor.' RogerN. Rosenberg, M.D.
Raven Press New York

Raven Press Ltd., 1185 Avenue of the Americas, New York, New York 10036
© 1991 by Roger N. Rosenberg. All rights reserved. This book is protected by
copyright. No part of it may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronical, mechanical, photocopying,
or recording, or otherwise, without the prior written permission of the publisher.
Made in the United States of America
Library of Congress Cataloging—in—Publication Data
Principles of neurosurgery/editor, Robert G. Grossman.
p. cm.
Includes bibliographical references.
Includes index.
ISBN 0—88167—750—7
1. Nervous systemﬁSurgery. I. Grossman, Robert G., 1933»
[DNLM: 1. Nervous System—surgery. 2. Nervous System Diseases.
WL 368 P957]
RD593.P75 1991
617.4‘8—dc20
DNLM/DLC
for Library of Congress 90-9219
CIP
Great care has been taken to maintain the accuracy of the information contained
in the volume. However, neither Raven Press nor the editors can be held responsible
for errors or for any consequences arising from the use of the information contained
herein. t
Materials appearing in this book prepared by individuals as part of their official
duties as U.S. Government employees are not covered by the above—mentioned
copyright.
9 8 7 6 5 4 3 21

Contents
10.
11.
12.
14.
15.
16.
17.
Anesthesia for Neurosurgical Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
Maurice S. Albin
Primary Diseases of the Skull . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 21
John P. Laurent
Congenital and Developmental Cranial Abnormalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25
John P. Laurent and William R. Cheek
Aneurysms and Carotid—Cavernous Fistulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 35
Robert R. Smith and Jimmy D. Miller
Cerebral Arteriovenous Malformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 55
Henry D. Garretson
Spontaneous Intracerebral Hematomas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 65
Howard H. Kaufman
Brain Tumors .................................................................... .. 113
Harold F. Young
Hydrocephalus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Albert B. Butler and David G. McLone
Focal Infections of the Central Nervous System, Skull, and Spine . . . . . . . . . . . . . . . . . . .. 179
Perry Black and Michael E. Carey
Trigeminal and Glossopharyngeal Neuralgia and Hemifacial Spasm . . . . . . . . . . . . . . . .. 223
Ronald I. Apfelbaum
Headlnjury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 235
Raj K. Narayan
Pain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 293
John D. Loeser
Movement Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 305
Robert G. Grossman and Winifred J, Hamilton
The Epilepsies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 319
Jerome Engel, Jr., Michel Levesque, Paul H. Crandall, D. Alan Shewmon,
Rebecca Rausch, and William Sutherling
Spinal Cord Tumors .............................................................. .. 359
James E. Rose
Syringomyelia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381
Howard M. Eisenberg and Richard L. Weiner
Vll

viii
/ CONTENTS
18. Vascular Malformations of the Spinal Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Lee H. Monsein and R. Nick Bryan
19. Neural Tube Defects
Michael Pollay
20. Disc Disease ................. ..
Clark Watts and Howard Smith
21. Spinal Stenosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Clark Watts and Kent Grewe
22. Traumatic Lesions of the Spine and Spinal Cord .................................. ..
Reinder Braakman
23. Peripheral Nerve Injury ........................................................... ..
Barton A. Brown
Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
387
399
415
437
447
467
473

CHAPTER 1
Principles 0fNeur0surgery,
edited by Robert G. Grossman. Rosenber © 1991.
Published by Raven Press, Ltd., New Yor .
Anesthesia for Neurosurgical Procedures
Maurice S. Albin
Preoperative Management, 2
Evaluation, 2
Premedication, 2
Physiological Dynamics of the Brain
and Spinal Cord, 3
Cerebral Blood Flow, 3
Spinal Cord Blood Flow, 3
Cerebral Metabolism, 3
PHCO2, P302, pH, 3
Autoregulation of Cerebral
and Spinal Cord Blood Flow, 4
Intracranial Pressure, 4
Anesthetic Agents and Adjuvants, 4
Halothane, 5
Enﬂurane, 5
Isoﬂurane, 5
Nitrous Oxide, 5
Barbiturates, 5
Ketamine Hydrochloride, 5
Etomidate, 5
Propofol, 5
Narcotics, Neuroleptics, and Benzodiazapines, 6
The historical development of anesthesiology has been
inextricably linked with the development of neurosur-
gery. Much of what is routine today in the practice of
anesthesia—the anesthesia record ("etherization chart"),
the awareness of the relationship of intracranial pressure
to blood pressure, the routine use of sphygmomanom—
etry during surgical procedures, blood salvaging, and the
use of ionically balanced salt solutions—is due to the pio-
neering neurosurgical work ofHarvey Gushing (1-5). In-
terestingly, another "great" in neurosurgery, Victor
Horsley, also made important contributions to anesthe-
sia (6-10). In 1882, Horsley and Spencer elucidated the
M. S. Albin: Department of Anesthesiology, University of
Texas Health Science Center, San Antonio, Texas 78284-
7838.
Muscle Relaxants, 6
Intraoperative Monitoring, 6
Arterial Blood Pressure, 6
Central Venous, Pulmonary Artery,
and Venous Air Embolism Catheters, 6
Venous Air Embolism, 7
Capnography, Mass Spectrometry,
and Pulse Oximetry, 9
Transcranial Doppler, 9
EEG and Evoked Potentials, 9
Brain Retraction Pressure (BRP), 10
Electrocardiography, 11
Urinary Output, 11
Chemistries, Blood Gases, and Ventilation, 11
Temperature, 12
Intraoperative Management, 12
Anesthesia Induction and Maintenance, 12
Induced Hypotension, 13
Cerebrovascular Ischemic Disease, 14
Posterior Fossa Surgery, 15
The Sitting Position and Spinal Cord Injury, 15
Postoperative Care, 16
References, 16
cardiovascular and respiratory changes produced by in-
creased intracranial pressure—nine years before Cush-
ing's classic publication on the subject (2,11). In 1888
Horsley and Gotch demonstrated that electric currents,
which they recorded with a capillary electrometer, are
produced in the mammalian brain. This work helped
lead to the development of the electroencephalogram
(EEG) (12). Horsley should also be given credit for being
the first neurosurgeon to use deliberate hypotension. In
his classic article, published in 1906, he states, "One of
the most striking features of the physiological action of
chloroform in the mammalian animal is that it causes a
marked fall in blood pressure. Consequently when a le-
sion is about to be extirpated and there is reason to ex-
pect considerable oozing, or when the brain is obviously
turgid with congestion, I always ask that the chloroform

percentage should be raised for, say, from a quarter to
half a minute to 1 or 3 percent. This at once induces a
convenient proportionate, and, of course, temporary,
anemia (6).
Horsley was also very involved with the safety of anes-
thetic agents in general, and with chloroform in particu-
lar. He was anesthetized with ether, chloroform, and ni-
trous oxide many times in order to evaluate the depth of
anesthesia. Horsley and Semon carried out animal stud-
ies with anesthetics and reported on the effect of ether on
the vocal Cords (13). Horsley's primaiy interest in anes-
thetics concerned the use of chloroform during neurosur-
gical procedures. Because of its potency, the use of chlo-
roform was undergoing scrutiny, and in 1901 the British
Medical Association appointed a Chloroform Commit-
tee, consisting ofDrs. Waller, Barr, Buxton, Sherrington,
Harcourt, and Horsley. The fruit of the committee's
work was the development, in l9l0, of Dr. Harcourt's
regulating device for automatically limiting the concen-
tration of chloroform in inspired air to a maximum of 2
percent. This device could also provide for the introduc-
tion of oxygen into the system.
The role of the anesthesiologist during neurosurgical
procedures and in the management of patients with
acute neurological dysfunction has changed remarkably
in the past 25 years. A better understanding of the sys-
temic repercussions to neurologic disease has led to (1)
an increased awareness of the importance of integrated
preoperative, intraoperative, postoperative, and special
care; (2) the use of more sophisticated techniques for
monitoring corporeal and neurologically oriented func-
tion; (3) the delineation of the processes of cerebral cir-
culation, cerebral metabolism, and intracranial compli-
ance, and their responses to anesthetic agents and
adjuvants; and (4) an increased awareness of the physio-
pathologic mechanisms and problems involved in pri-
mary neurologic disorders.
The past decade has seen incredible development in
molecular biology and biotechnology, the waters of
which have been continuously lapping at the neuro-
sciences. We now have a better understanding of the
pharrnacokinetics and metabolic fate of anesthetic
agents and adjuvants and are beginning to understand
cellular responses to injury. We have also witnessed a
growing number of monitoring devices (pulse oximetry,
processed EEG, the transcranial Doppler, and trans-
esophageal echocardiography, to name but a few) that
may affect mortality and morbidity, and we have seen
the development of new anesthetic agents and adjuvants
whose effect on cerebrovascular response has been thor-
oughly evaluated. Also important, the treatment of the
patient with acute neurological dysfunction has been
considerably improved by the recent trend toward sub-
specialization in the area of critical care medicine.
Optimal management of the neurosurgical patient in-
volves a high level of cooperation between the anesthesi-
ologist and neurosurgeon that transcends focusing solely
on the intraoperative period and eliminates the casual
posting of a complicated case the evening before surgery.
In addition to the complex needs of each individual pa-
tient, the litigious nature of our society mandates this
close working relationship between the anesthesiologist
and neurosurgeon.
PREOPERATIVE MANAGEMENT
Evaluation
The preoperative evaluation should be as complete as
possible, whether the patient is scheduled for a surgical
procedure, diagnostic evaluation, or observation in a spe-
cialized care unit. This is especially true of the critically
ill and debilitated neurosurgical patient. CNS tissue is
exquisitively vulnerable to oxygen deprivation and sen-
sitive to changes in CO2 concentration. Thus, our pri-
mary role during the preoperative period is to "normal-
ize" the brain and, if this organ is compromised, to
compensate for the loss of autoregulation.
Critical preoperative parameters include adequate ox-
ygen delivery, proper pulmonary function, normovol—
ernia, maximal cardiac responses, and no bleeding dys-
crasias. These can be screened by thorough physical
examination, chest films, blood tests (including hemato-
crit, hemoglobin, white and red cell counts, differential,
platelets, prothrombin time, and partial thromboplastin
regeneration time), electrocardiogram (ECG), and pul-
monary function tests. Also, because of the use of renal
diuretics and hyperosmotic agents, a chemistry screen
including electrolytes, blood urea nitrogen, creatinine,
and glucose is a minimal requirement. Liver function
tests and enzymes will complete the screen and can be
valuable for baseline data.
The patient scheduled for neurovascular (aneurysm,
arteriovenous malformation) surgery may need special
precautions in the preoperative period to ensure an ade-
quate circulatory blood volume. Blood volume can be
determined directly by isotopic techniques for both
plasma and red cells and indirectly by measuring central
venous and/or pulmonary artery and capillary wedge
pressures as well as noting urinaiy output. Blood pres-
sure (BP) control can be difficult in the aneurysm patient
(with or without vasospasm), making it especially im-
portant to be able to determine arterial blood pressure
accurately and to appreciate circulating blood volume.
Premedication
One must assume that any patient about to undergo
surgery who exhibits signs of increased intracranial pres-
sure (ICP) or who is comatose or conscious but disor-
iented will be placed in a special area or unit for close

SANESTHESIA FOR NEUROSURGICAL PROCEDURES / 3
observation. Heart rate, ECG, respiratory rate, BP, and
ICP should be monitored as needed.
Premedication can be of critical importance in a pa-
tient who has increased ICP. In this individual, we must
aim to avoid any increase in cerebral blood volume, espe-
cially if the patient is near the point on the compliance
curve where a small increase in cerebral blood volume
will give a marked increase in ICP. Any drug or agent
that will in any way cause respiratory embarrassment
should be avoided. Conversely, the proper use ofben/o-
diazepine derivatives to tranquilize the patient and to
attenuate seizure activity is also important, especially in
the patient with an intracranial aneurysm who might
develop a serious bleed prior to surgery because of appre-
hension and a concomitant increase in blood pressure.
When a surgical procedure is to take place in the mo1n—
ing, common practice allows the full supper meal to be
eaten the night before; after midnight, food and drink are
withheld. A study has shown that postoperative emesis
of solid food can take place as long as 48 hours after the
withholding of oral food (14). Because of this potential
hazard, it has been suggested that, whenever possible,
patients have clear liquid for both lunch and supper the
day before surgery. Among patients whose stomachs
were aspirated before surgery, a significant incidence of
gastric contents with a pH less than 2.5 has been noted.
This observation raises the possibility ofpulmonaiy aspi-
ration of acidic material, should emesis occur. We rou-
tinely use prophylactic antacids for both elective and
emergency surgery. Sodium citrate (30 ml of 0.3 M)
given orally prior to going to the operating room will
rapidly raise the gastric pH above 3.0 and, should aspira-
tion occur, prevent the development of chemical pneu-
monitis.
The use of histamine H2—receptor antagonists, such as
ranitidine and cimetidine, has been found effective in
inhibiting gastric acid secretion when given the night be-
fore surgery and repeated with the preoperative medica-
tion. It is also our custom to give metoclopramide hydro-
chloride as a premedicant. This drug has antiemetic
properties as well, as it produces accelerated gastric emp-
tying and increases the resting tone of the esophageal
sphincter.
PHYSIOLOGICAL DYNAMICS OF THE BRAIN
AND SPINAL CORD
Cerebral Blood Flow
In the human, total mean cerebral blood ﬂow (CBP)
(15,16) is about 50 ml/100 g/min"1. However, it is non-
uniform and varies with the anatomical area and with
the involvement of gray or white matter. In general, gray
matter ﬂow (80 ml/100 g/min"1) is higher than white
matter ﬂow (20 ml/100 g/min"1). The regional cerebral
blood ﬂow may vary widely, depending in general on the
local metabolic activity. The EEG becomes slower when
cerebral blood ﬂow drops below 20 ml/100 g/min"1 and
becomes ﬂat at or below 15 ml/100 g/rnkr . Below 15
ml/100 g/min"1, irreversible changes occur. All these
changes are predicated at the normal temperature of
37°C, since there is a 50 percent decrease in brain oxy-
gen demand for every 10°C decrease in brain tempera-
ture.
Spinal Cord Blood Flow
It appears that mean spinal cord blood flow (SCBF)
(17) is similar in magnitude to that of mean cerebral
blood flow, with lumbar > cervical > thoracic blood
flow.
Cerebral Metabolism (15,16)
Oxygen uptake (CMRO2) is about 3.5 ml/100 g/min"1
in the adult and is about double this figure in the neo-
nate. The ability of the brain to use anaerobic pathways
is severely limited. When the Paoz decreases to near 30
mmHg or when 02 delivery to the brain is stopped, loss
of consciousness quickly ensues. Glucose uptake into the
brain (the cerebral metabolic rate for glucose) ranges
from 3.5 to 5.0 mg/100 g/min"1, with more than 90 per-
cent of the consumption being aerobic. This aerobic me-
tabolism of glucose produces adenosine triphosphate
(ATP) which, hydrolyzed into adenosine diphosphate
and inorganic phosphate, produces considerable energy
release. This process fuels most of the neurochemical
reactions in the brain and spinal cord.
Pacoz, P2102, pH(15,16)
The principal chemical mediator of cerebral blood
ﬂow is the arterial blood carbon dioxide tension (Pacoz)
and from 20 to 80 mmHg the cerebral blood ﬂow vaiies
linearly with Pacoz in normoxic individuals (Fig. 1).
Thus, hyperventilation with resulting hypocarbia is used
to reduce brain volume by decreasing the cerebral blood
ﬂow and hence the cerebral blood volume. Conversely,
increases in Pacoz caused by respiratory obstruction or
inadequate ventilation can increase cerebral blood ﬂow
and cerebral blood volume, placing the brain at risk of
increased intracranial pressure. Signiﬁcant increases in
cerebral blood flow do not occur until the arterial blood
oxygen tension (Paoz) moves below 50 mmHg. Increases
in Paoz above the normal 100 mmHg will decrease cere-
bral blood flow, and inhalation of 80 to 100 percent oxy-
gen can lower cerebral blood ﬂow by 10 percent. With
normal blood pH ranging from 7.35 to 7.45, alkalemia
(pH 7.45) can slightly reduce cerebral blood flow, and
acidernia (pH 7.35) may slightly increase it.

4 / CHAPTERI
25 75 125
Pressure (mmHg)
FIG. 1. Cerebral blood flow responses due to changes in
Pacoz P302 and blood pressure (BP).
Autoregulation of Cerebral and Spinal Cord
Blood Flow (17)
Autoregulation allows the brain and spinal cord to
keep blood flow constant through a wide range of pres-
sures. During increases in mean arterial pressure, cere-
brovascular resistance increases, and likewise, during de-
creases in mean arterial pressure, cerebrovascular
resistance decreases. The lower and upper limits of auto-
regulation in the brain and spinal cord appear to be simi-
lar, in the range of 50 to 60 mmHg mean arterial pres-
sure for the lower limit and in the range of 140 to 160
mmHg mean arterial pressure for the upper limit. When
the mean arterial pressure falls below 50 to 60 mmHg,
flow becomes passive, and when the mean arterial pres-
sure exceeds l40 to 160 mmHg, the blood brain barrier
can become disrupted, with cerebral edema occurring.
Autoregulation can also be lost under conditions of
ischemia, hypoxia, hypercarbia, and trauma and be-
cause of the effects of some anesthetics and induced hy-
potensive agents. In persons with hypertension and in
the elderly, the autoregulatory curve is shifted to the
right, increasing the lower and upper limits ofautoregula—
tion.
The concept of adequacy of cerebral perfusion is, of
course, related to autoregulation. Cerebral perfusion
pressure (CPP) is denned as the difference between the
mean arterial blood pressure (MAP) and intracranial
pressure (ICP). Thus, CPP = MAP — ICP, with a normal
cerebral perfusion pressure being 90 to 100 mmHg. Be-
cause cerebral blood ﬂow beoomes passive at or below
the lower limits of autoregulation (50 to 60 mmHg mean
pressure), this relationship is especially critical during
periods of induced hypotension. In the normal individ-
ual, the mean arterial pressure is the critical factor in
determining the cerebral perfusion pressure because in-
tracranial pressure is relatively constant. A closer look at
the formula, CPP = MAP — ICP, makes one realize that
we are recasting the Gushing Response, which states
that, as intracranial pressure increases and produces
brain stem ischemia, the blood, pressure increases to pro-
vide adequate cerebral perfusion. The associated brady—
cardia is a vagally mediated response to increase the end-
diastolic filling pressure that assists in overcoming the
intracranial pressure gradient.
Intracranial Pressure (2,12,15,16,18)
Because the brain lies within the rigid cranial vault,
the intracranial pressure can be modiﬁed by changes in
brain volume, blood volume, or CSF volume. The intra-
cranial pressure—volume relationships can be illustrated
by a compliance curve where intracranial pressure, mea-
sured in mmHg, is plotted against changes in intracra-
nial volume. As shown in Figure 2, between points 1 and
2 there is little or no change in intracranial pressure, in
spite of a slight increase in intracranial volume. This indi-
cates that the mechanism allowing for spatial compensa-
tion is still operant. However, when one moves from
point 2 to point 3, compliance is reduced and the intra-
cranial pressure becomes abnormal. In going from point
3 to point 4, a very small increase in intracranial volume
produces a marked increase in intracranial pressure.
This compliance curve indicates the importance of anes-
thesia surveillance to insure that anesthesia agents and
adjuvants are not employed that will increase the intra-
cranial volume, that adequate tensions of oxygen are
used, and that ventilatory techniques producing hypo-
carbia are employed.
ANESTHETIC AGENTS AND ADJUVANTS
In neuroanesthesia, our aim is to maintain an optimal
cerebral perfusion pressure while minimally challenging
the autoregulatory capacity of the brain. Either primarily
or because of associated secondary effects, anesthetic
agents influence cerebral blood flow, cerebral metabolic
rate of oxygen consumption, cerebral perfusion pressure,
and cerebrovascular resistance. The secondary effects
can relate to changes in body temperature, blood CO2
and O2 tensions, or arterial and venous pressures. In gen-
eral, the volatile inhalation anesthetics are cerebrovascu-
lar dilators; they increase cerebral blood flow and can
increase cerebral blood volume and intracranial pres-
sure, although the last two effects may be modiﬁed by
induced hypocapnia. The relationships between cerebral
80-
60-
40-
CL 20-
O
lntracranial Volume
FIG. 2. lntracranial pressure—volume curve.

ANESTHESIA FOR NEUROSURGICAL PROCEDURES / 5
blood ﬂow and cerebral metabolic uptake of oxygen are
extremely important. Most of the inhalation anesthetic
agents that increase cerebral blood flow achieve this by
uncoupling the relationship between flow and metabo-
lism and can thus "steal" blood from an area of high
functional demand. Another important characteristic of
the volatile agents is their ability to alter autoregulation.
Halothane
Halothane (15,19,20,21) has been shown to be a cere-
brovascular dilator, increasing cerebral blood flow and
decreasing the cerebral metabolic rate of oxygen. In pa-
tients with moderate intracranial hypertension, halo-
thane may cause transient increases in intracranial pres-
sure. These can often, but not always, be minimized or
eliminated by hyperventilation, inducing hypocapnia.
Intracranial pressure changes can also develop after halo-
thane because of alterations in cerebral perfusion pres-
sure secondary to hypotension caused by this agent.
Enﬂurane
Enﬂurane (15,22,23,24) can increase cerebral blood
flow, and hyperventilation with accompanying hypocar—
bia may not be successful in attenuating intracranial hy-
pertension. An increase in intracranial hypertension and
a resultant decrease in mean arterial blood pressure (be-
cause of the effect of enﬂurane on myocardial contractil-
ity) may also cause a decrease in cerebral perfusion pres-
sure. Enflurane has the added liability of stimulating
seizure activity at reduced CO2 tensions.
Isoﬂurane
Isoflurane (l5,20,25,26,27,28) appears to be a useful
agent in neuroanesthesia practice because, when used in
inspired concentrations of up to 1 percent (1.1 mean
alveolar concentration), there is only a small increase in
cerebral blood flow. Recent experimental studies, how-
ever, appear to indicate that isoflurane may cause a steal
of blood flow from the ischemic cortex to the cerebellum
and brain stem and that cerebral blood ﬂow may mark-
edly decrease in the face ofintracranial hypertension and
hypocarbia.
Nitrous Oxide
Nitrous oxide (1 5,28,29,30) may cause an elevation in
intracranial pressure, which hypocarbia may not attenu-
ate, in patients with space—occupying lesions. The combi-
nation of N20 with other inhalational agents may cause
a marked increase in cerebral blood ﬂow in patients with
a mass lesion and intracranial hypertension.
Barbiturates
Barbiturates (15,20,31) have been shown to produce
dose—dependent cerebrovascular constriction, with a con-
comitant decrease in both cerebral blood flow and cere-
bral oxygen uptake. The increase in cerebrovascularresis—
tance found after barbiturate administration may tend
to lower intracranial pressure and hence minimize the
response to hypoxia. The ability of barbiturates to pro-
tect the brain from experimental focal ischemic insults
has been described. Thiopental can provide cerebral pro-
tection when given at a level to maintain EEG silence
during cardiopulmonary bypass for coronary arteryj
grafting procedures (32). I
Ketamine Hydrochloride
Ketamine hydrochloride (15,33,34,35,36) has been
shown to increase cerebral blood flow, cerebral oxygen
uptake, and intracranial pressure even in patients with
normal CSF pathways. Hence this agent should be
avoided in patients suspected of having increased intra-
cranial pressure.
Etomidate
Etomidate (37,38), like thiopental, decreases cerebral
blood flow and the cerebral metabolic rate of oxygen
uptake. It can be used by bolus injection or infusion but
has the disadvantage of suppressing ACTH—cortisol pro-
duction. This may not be a problem in many neurosurgi—
cal cases since corticosteroids are often routinely em-
ployed prior to, during, and after surgery.
Propofol
Propofol (39,40) is a new intravenous short—acting an-
esthetic agent which can be used by bolus injection or
through titrated infusion. Propofol simultaneously de-
creases CBF and CMRO2. Moss and Price demonstrated
in 11 patients undergoing craniotomy for a supratento—
rial lesion that propofol was able to reduce brain retrac-
tion pressure by decreasing cerebral blood volume sec-
ondary to cerebral vasoconstriction. Because ofthe rapid
metabolism of propofol, the return to consciousness is
usually very rapid after termination of the infusion. One
of the problems associated with propofol is that hypoten-
sion can develop with too rapid an infusion of the drug,
especially in patients with a contracted blood volume. A
technique for the delivery of propofol would be an initial
infusion of 30 mg/kg/hr for 5 minutes, followed by an
injection of 6.0 mg/kg/hr for maintenance.

6 / CHAPTER1
Narcotics, Neuroleptics, and Benzodiazepines
Narcotics (morphine, rneperidine, fentanyl, sufen—
tanil, alfentanil), neuroleptics (fentanylplus droperidol),
and benzodiazepines (l5,20,4l—48) generally cause par-
allel and dose—related decreases in both cerebral blood
ﬂow and cerebral metabolic rate of oxygen uptake. They
generally have little effect on intracranial pressure, al-
though the neuroleptics and benzodiazapines can cause
small reductions in lCP in patients with normal cerebro—
spinal ﬂuid pathways and in those with mass lesions.
Midazolam is a relatively new, potent, water—soluble
benzodiazapine with a half—life considerably shorter than
diazepam (49,50).
Muscle Relaxants
Because of their ability to release histamine or because
of their effect in activating the cerebral cortex and in-
creasing cerebral blood flow, muscle relaxants (51-56)
may have an effect on intracranial dynamics. Of the
nondepolarizing agents, the only one that does not cause
the release of histamine is vecuronium bromide. In order
of histamine release, pancuroniurn bromide < atracu—
riurn besylate < rnetacurine < d—tubocurarine. The de-
polarizing relaxant, succinylcholine, has recently been
implicated in causing an increase in intracranial pressure
in patients with space—occupying lesions when pretreat-
ment with a nondepolarizing relaxant was not used.
INTRAOPERATIVE MONITORING
Miniaturization and complex computer applications
are now opening the door to the collection of more accu-
rate physiological and biochemical data and to the analy-
sis of this data to develop predictability curves for spe-
ciﬁc parameters.
Arterial Blood Pressure
Positional changes and induced hypotension are often
necessary in microneurovascular surgery, and they make
it important to provide the surgeon with highly accurate
information concerning moment—to—moment changes in
arterial blood pressure. Although indirect methods are
useful, intravascular monitoring procedures are more re-
liable and sensitive; the radial artery is most commonly
used for this purpose. Indwelling catheters larger than 20
gauge should be avoided. The arterial line can be kept
open by discontinuous ﬂushing with heparinized crystal-
loid solution, or by using a pressure infusor.
For the calculation of cerebral perfusion pressure
(CPP), the intravascular arterial pressure transducer is
aligned with the highest part of the skull if the patient is
not supine. This calculation (mean arterial blood pres-
sure minus either cerebral venous pressure or intracra-
nial pressure, whichever is higher) can be critical, be-
cause even small decreases below the threshold for
cerebral blood flow autoregulation may be deleterious.
The intravascular catheter also serves as a source of arte-
rial blood for blood gases and other biochemical and
hematological determinations.
For conventional cardiovascular recording in the su-
pine or prone position, mean arterial pressure is refer-
enced at the right atrial level (fourth intercostal space
and midaxillary line). However, when the head is ele-
vated above the heart level, the transducer reference
point should be the superior margin ofthe incision. This
is important in patients operated on in the sitting posi-
tion because there is roughly a 1.0 rnrnHg decrease in the
CPP for every 1.0 cm of the gradient above the fourth
intercostal space midaxillary line and the superior mar-
gin ofthe incision. Hence, in a sitting—position neurosur-
gical procedure with a 25 cm gradient and a mean arte-
rial blood pressure (transducer referenced at right atrial
level) of 75 mmHg, the cerebral perfusion pressure
would be 75 minus 25, or 50 mmHg, which is at the
lower limits of autoregulation and is certainly inade-
quate over any sustained period of time. A knowledge of
this gradient is also important with regard to venous air
embolism, since a relatively negative pressure exists
when the head or spine is above the heart level. This
gradient is needed to entrain air into the venous system.
Central Venous, Pulmonary Artery,
and Venous Air Embolism Catheters
Central venous pressure monitoring lines have been
used to detect acute circulatory changes, to evaluate vol-
ume status, and to aspirate venous air emboli. Unfortu-
nately, the central venous pressure basically reflects the
functional state of the right ventricle, which quite often
does not indicate the status of the left heart. One can
note a normal central venous pressure in the face of
marked changes in the functional characteristics of the
left heart. An important advance has been the develop-
ment of balloon flotation catheter techniques (Swan-
Ganz), allowing for measurements of pulmonary capil-
lary wedge pressure that closely reflect left atrial pressure
and serve as an index of left ventricular ﬁlling pressure
(57,58).
The pulmonary capillary wedge pressure can also de-
note shifts in ﬂuid from the pulmonary capillaries into
the interstitial tissue and alveoli, indicating pulmonary
congestion and/or the development of pulmonary
edema. The triple—lumen Swan—Ganz catheter can also
give pulmonary artery and right atrial pressures, as well
as having the ability to do repeated cardiac output mea-
surements by the therinodilution technique. With the
knowledge of ﬂow and pressure, vascular resistances can
be easily calculated and the addition of hematocrit, he-

ANESTHESIA FOR NEUROSURGICAL PROCEDURES
moglobin, and blood gas values allows calculation of a
complete cardiopulmonary physiological proﬁle, includ-
ing shunt fraction, stroke volume and oxygen transport.
This technique is especially useful in difficult cases in-
volving aneurysms and arteriovenous malformations
and is an excellent method for controlling volume re-
placement and for continuous monitoring during the in-
traoperative and postoperative periods. The ability to
monitor plasma colloid oncotic pressure is also impor-
tant because a marked decrease in colloid oncotic pres-
sure can produce pulmonary edema even in the face of
normal or slightly elevated pulmonary capillary pressure
(hypoproteinemia) or a large volume of crystalloids.
For possible air aspiration, the proper positioning of
the central line can be accomplished by radiographic
placement and ECG verification (P—wave changes). Op-
timal placement of the catheter for maximal aspiration
appears to be in the superior vena cava, 1.0 cm prior to
the entrance of the right atrium. The multiorifice (5-
hdle), l4—gauge, Bunegin—Albin catheter is far superior to
the single orifice catheter since better than 95 percent of
entrained air can be recovered (59). A triple—lumen ve-
nous air aspiration catheter (Cook Inc., Bloomington,
Indiana), designed by Bunegin and Albin, allows for ve-
nous air aspiration, measurement ofcentral venous pres-
sure, and ﬂuid infusion (through two 18—gauge side-
ports). Placement of central venous catheters is
facilitated by the use of a Seldinger—type guide wire with
a J—shaped tip (60). For this type of catheter placement,
the basilic, cephalic, internal, or external jugular vein
may be used. Because of the many reported complica-
tions (pneumothorax, hemothorax, mediastinal shift,
etc.), we have generally abandoned using the subclavian
vein for placement of the air aspiration—central line cath-
eter. A recent publication by the Food and Drug Admin-
istration pointed out the risks and hazards of central line
placement, noting particularly vascular erosion and peri-
cardial tamponade (61). It should be emphasized that
when the line is used for central venous pressure moni-
toring or for air aspiration, it should not be placed in the
right atrium, but rather the tip should rest in the superior
vena cava just before the right atrium. Because of the
rigidity of the plastics used in these catheters, catheter
"whipping" can occur in the right atrium (especially
when a coiled loop is present). This may cause heart
chamber penetration. Because of the "stiffness" ofpoly—
thylene, polyvinyl, and polyurethane plastics, we have
evaluated the pressure—recording characteristic of sili-
cone rubber catheters and found them to be as accurate
as the other types of plastic material (62), Studies are
now being carried out to test the "whipping" characteris-
tics of silicone rubber.
Venous Air Embolism
It is remarkable that the physiopathology, diagnostic
criteria, and treatment of venous air emboli had been
thoroughlyelucidatedbyscientist—physiciansfromthree
differentcountriesandtwocontinentsbyl885.In839
Amussat,ofFrance,publisheda245—pagebooktitled
Researchont/1eACCidentalIntroduCtionofAirintothe
Veins (63). At the 13th meeting of the British Associa-
tion for the Advancement of Science in 1843, Erichsen
presented a communication, "On the Proxirnate Cause
of Death after the Spontaneous Introduction ofinto
the Veins, with Some Remarks on the Treatment of line
Accident" (64). Finally, in 1885, the Annals ofSurgery
contained a 115—page dissertation by Senn titled An
Experimental and Clinical Study of Air Embolism" (65).
These three investigators described, collected, and re-
viewed hundreds of clinical cases of venous air embolism
that had been reported and developed a host of experi-
ments using a variety of animal species (66). This trio
described the heart tone changes we now call the "mill
wheel murmur," the gasping respirations, cyanosis, and
cardiovascular collapse. They spoke about mechanical
distension of the right side of the heart owing to air bub-
ble accumulation and about asphyxia from obstruction
to the pulmonary circulation and how it often produces
acute "anemia of the brain" and "acute cerebral is-
chemia." They also were familiar with the different re-
sponses to venous and arterial air embolism, and they
experimentally described and clinically documented
that the development of gradients between the incisional
area and the right heart area was critical in promoting
the movement of air ("the force of gravitation"). Amus-
sat, Erichsen, and Senn identified venous air embolism
in cases involving internal jugular, external jugular, fa-
cial, axillary, anterior thoracic, superficial cervical, femo-
ral, internal saphenous, uterine, pulmonary, and diploic
veins, as well as the superior longitudinal and uterine
sinuses. They advocated a prophylactic approach involv-
ing painstaking hemostasis by compression, ﬂooding the
operative field, and vein ligation. In a number of elegant
experimental studies, they demonstrated that air in the
right side ofthe heart could be removed by needle aspira-
tion or by aspiration through a cannula or catheter intro-
duced into the atrium via the jugular vein.
If one scans the surgical literature published during
the 1800s, one can identify more than 150 articles, re-
ports, reviews, and books on venous air embolism. It is
important to remember that venous air embolism was a
much feared complication during the nineteenth cen-
tury in the spontaneously ventilating (anesthetized or
nonanesthetized) patient and that many surgical proce-
dures were carried out in the sitting or semisitting posi-
tion. Despite refinements in surgical and anesthetic tech-
niques, venous air emboli continue to occur, and not
only in neurosurgery. Recent case reports have described
venous air embolism in a number of non—neurosurgical
cases, including cesarean sections, hysterectomies, and
hip replacement procedures, in which relatively small
gravitational gradients exist in the presence of a plethora
of open vascular channels (67-71). We just recently de-

8 / CHAPTER1
tected a venous air embolism during a radical prostatec—
tomy with a 12.0 cm gradient. This embolism resulted in
the aspiration of 10.0 ml of air, hypotension, and hypo-
carbia (submitted for publication).
In terms of venous air embolism, the sitting position is
as controversial today as it was when it was first intro-
duced. In 1913 in Paris, DeMartel adopted the sitting
position for brain tumor surgery under local anesthesia.
In the United States, Frazier began using this position for
operations on the gasserian ganglion in 1928, and it has
been popular ever since. In neurosurgery, the gradient
between the right heart and the incisional area in the
head or neck (as seen in the sitting position) increases the
subatmospheric pressure in the open venous channels,
thereby enhancing the possibility of developing a venous
air embolism. We have noted that, even with a gradient
of not more than 5 cm in the lateral, supine, or prone
position, significant quantities of air can enter the ve-
nous system (72). In 1969, a death from venous air em-
bolism was reported in which the patient was in the
prone position and the head was elevated 10 cm above
the heart level (73). The neurosurgical practice of elevat-
ing the head above the heart level to allow for adequate
venous drainage creates a gradient and potential source
of venous air embolism should the veins or dural sinuses
be entered. This gravitational gradient is enhanced by
decreasing the mean intrathoracic pressure as well as by
increasing the distance of the entrance point above the
right side of the heart. A contracted blood volume and
low central venous pressure will also enhance the effects
of a small gradient. The right he art reference point is on a
transverse plane running through the fourth intercostal
space. For these reasons, venous air embolism can occur
during larninectornies using the Hastings frame, since
there is a reduction in the intrathoracic and intra—abdo—
minal pressures that favors the development of a nega-
tive pressure and hence an increased gradient. With pa-
tients in the Hastings frame, caval pressures ranging
from +2.0 to -6.6 cmH2O have been reported (73). We
have recently described two cases of venous air embo-
lism that occurred during lumbar laminectomy in the
prone position; one case utilized the Hastings frame, and
the other employed a "four—poster" that placed the pa-
tient in a position similar to that in the Hastings frame
(75). In one of the cases, air bubbles were noted in the
coronary vessels and 40 ml of air was aspirated from the
right ventricle during autopsy.
Incidence rates of venous air embolism have changed
since the introduction of the Doppler ultrasonic air bub-
ble detector by Maroon and colleagues in 1968 (76).
Prior to the use ofthis detector, venous air embolism was
reported to occur in 0.98 to 15 percent of neurosurgical
operations performed in the sitting position. With
Doppler monitoring, however, the reported incidence
rate has ranged from 21 to 60 percent (77-79). Venous
air embolism causes concern because the entrance of a
large quantity of air into the right heart can produce an
air lock that can block adequate ﬁlling of the heart. If the
air is not evacuated, this can lead to cardiac arrest. Be-
cause of solubility factors, the bubble volume is mark-
edly increased in the presence of nitrous oxide, and at a
1:1 N2O—O2 concentration the bubble size is doubled
(80). Another danger of a large volume of air in the right
heart is that if the right atrial pressure becomes greater
than the left atrial pressure and if a patent foramen ovale
exists, the air could enter the left side of the heart,
thereby creating a paradoxical air embolism (81). Rever-
sal of transatrial gradients has been demonstrated to oc-
cur in the sitting position with the employment of posi-
tive end—expiratory pressure, and it is possible that
frequent Valsalva maneuvers during a neurosurgical
procedure would enhance this gradient and the chance
of paradoxical air embolism occurring (82,83). The en-
trance of air into the pulmonary vasculature can pro-
duce severe pulmonary perfusion deficits in humans, as
noted in technitium—macroaggregated albumin scans
(72). It is also possible that the passage of air in large
quantities might so overwhelm the pulmonary vascula-
ture that passage across the capillary bed might occur,
resulting in coronary sinus and/or cerebral air embo-
lism (84).
Signs of venous air embolism may include spontane-
ous (gasping) respiration, increases in central venous
pressure, dysrhythmias, ECG changes, hypotension,
changes in heart sounds, and cyanosis. Unfortunately,
the appearance of the mill wheel murmur is a late occur-
rence and indicates that a substantial quantity of air has
already been aspirated into the right side of the heart.
The employment of ultrasonic Doppler techniques for
air bubble detection has opened a new era in rapid, sensi-
tive monitoring that allows for detection of as little as 0.1
ml of air. Criteria for optimal Doppler transducer design
include adequate depth of ﬁeld, beam coverage across
the whole right atrium, and competent squelching cir-
cuitry to eliminate radio frequency interference during
electrocoagulation. Calibration for transducer localiza-
tion is easily accomplished by rapid injection of a bolus
(10 ml) of a crystalloid solution through the central cath-
eter, the resultant turbulence giving a sound similar to
that of air inﬂow (85).
Capnographic techniques for measuring levels of CO2
in the expired air (ETCO2) have been used successfully
for venous air embolism detection. Similarly, a rise in
pulmonary artery pressure (PAP) occurs in the presence
of small quantities of air. The overall sensitivity ranking
for detecting venous air embolism is: Doppler > PAP >
ETCO2 > MAP > esophageal stethoscope (86).
Two devices have been reported that may further im-
prove our ability to diagnose venous air embolism. The
first is a transesophageal Doppler probe that has a 360-
degree are and the capability to look at both the right and
the left side of the heart simultaneously (87). The second
device is a transesophageal echocardiographic unit with
excellent sensitivity to air that also has the capability to

ANESTHESIA FOR NEUROSURGICAL PROCEDURES / 9
monitor both sides of the heart (88,89). The advantages
of these devices are apparent, especially for monitoring
the occurrence of paradoxical air embolism.
Because a gradient is usually present in intracranial
procedures and because the possibility exists that venous
air embolism will occur, it is customary in some institu-
tions to monitor for venous air embolism with a Doppler
monitor and a central air—aspiration catheter during any
intracranial procedures as long as even a slight gradient
exists.
When a venous air embolism is suspected or detected,
the surgeon should be alerted to look for the site of en-
trance of air, and the air should be aspirated through the
central line. N2O should be discontinued, the patient put
on 100 percent 62, and attention paid to change in the
ECG and end—expiratory CO2. If vital signs change as a
result of large quantities of air, symptomatic treatment is
used to combat the possible hypotension, arrhythmias,
or cyanosis that may occur. The esophageal stethoscope
may resound with a mill wheel murmur, usually a late
occurrence, which indicates the uptake of a large volume
of air into the right heart. With massive air embolism or
inability to deal with steady entrainment of air, it may be
necessary to place the head at or below heart level and to
abort the operative procedure.
The hallmarks of venous air embolism treatment ap-
pear to be early detection and aspiration with a
previously inserted central catheter. Over the years, neu-
rosurgeons and anesthesiologists have become impatient
and annoyed with the difficulties involved in placement
of this important central line (90). However, improved
catheters and improved techniques for their precise
placement have substantially simpliﬁed insertion of a
central line (60,91). That the problem of venous air em-
bolism still plagues us is reflected by reports that indicate
a relatively high incidence of venous air embolism in
children undergoing surgery (92,93).
Capnography, Mass Spectrometry, and Pulse Oximetry
Our ability to provide safe anesthesia has been ad-
vanced significantly by the development of these three
monitoring entities.
Capnography (end tidal CO2 monitoring) is extremely
important during neurosurgical procedures because CO2
is a major chemical determinant of CBF. Breath—by—
breath concentrations of CO2 can be visualized using
Capnography. The capnograph can be used as an inde-
pendent unit or incorporated with another monitor.
Mass spectrometry enables one to monitor the con-
centration of the inhaled and exhaled gases, including
02, CO2, N2, and inhalational anesthetic agents such as
N2O, halothane, enﬂurane, and isoﬂurane. This type of
unit samples discontinuously as it evaluates the gases
serially from each operating room. However, a continu-
ous readout on inhaled—exh'aled CO2 has been available
during the past five years. The diagnosis of venous air
embolism can be improved using this technology since
decreases in end—tidal CO2 and increases in end—tidal N2
may indicate the occurrence of an air embolism.
Pulse oximetry is now becoming part of the standard
of care in anesthesiology. This noninvasive device for
measuring oxygen saturation (SaO2) is applied to a
finger, rapidly detects arterial desaturation, and is an im-
portant tool for recognizing the development of hypoxic
hypoxemia.
Transcranial Doppler
The transcranial Doppler (TCD) has been used in the
past as a diagnostic and monitoring device to assess veloc-
ity of ﬂow in both intracranial and extracranial blood
vessels (94,95). Recent experimental data by Albin and
coworkers has indicated that the TCD also has the capa-
bility to detect and differentiate small quantities of air
(0.8 /til) from paniculate matter (1 X 1071.0 micron latex
spheres) circulating in the middle cerebral aitery of the
rhesus monkey (96).
Embolic phenomena appear to be the etiologic basis
for the development of stroke and neurobehavioral defi-
cits following carotid endarterectomy or cardiopulmo-
nary bypass. They can be characterized as either a mac-
roembolism of air or particulate matter, or a
rnicroembolism of air, rnicroaggregates, or foreign parti-
cles. Neurologic deficits resulting from emboli are focal
in nature but appear diffuse owing to widespread embo-
lization.
In 1984, 200,000 individuals underwent coronary ar-
tery bypass grafts (CABG) in the United States, and this
number may be doubled in 1990 (97). If the postopera-
tive stroke rate of 5.2 percent in the prospective 1983
Cleveland Clinic CABG study and 5.0 percent in the
1985 prospective University of Newcastle CABG study
is accepted, at least 10,000 cases of stroke annually can
be predicted following CABG procedures in the United
States (98,99).
After CABG, carotid endarterectomy is the most com-
mon vascular procedure performed in the United States,
with at least 103,000 endarterectomies performed in
1984 (100). Although the number of carotid endarterec-
tomies appears to be declining, intraoperative emboliza—
tion accounted for one—third of the major strokes re-
ported by Sundt and coworkers (101). The ability of a
TCD density scan to detect and differentiate aerie from
particulate emboli would help in the early diagnosis and
treatment of these embolic phenomena.
EEG and Evoked Potentials
The clinical use of electroencephalography (EEG) to
monitor anesthesia depth produced by inhalational and
intravenous agents was pioneered by Faulconer, Pender,

10 / CHAPTER1
Bickford, and Courtin (102-104). These investigators
also correlated electrophysiological responses and anes-
thetic depths with blood levels of the inhalational agents.
Unfortunately, the administration ofpremedication and
other drugs having electrophysiological effects makes it
extremely difficult to use EEC to determine depth of
anesthesia.
Because of its correlation with cerebral blood flow,
EEG has been used as an indicator of changes in brain
state during hypotension, hypocarbia, and hypercarbia
and for monitoring cerebral electrical activity during ca-
rotid endarterectorny and other neurovascular proce-
dures (105-106). The EEG has also been used to rnoni-
tor brain perfusion during open—heart surgery, and
nonexistent or low—level EEG activity has been found to
correlate well with serious postoperative neurological def-
icits (107).
Spectral cornpression EEG techniques using Fourier
processing eliminate the bulky EEG tracing, allow for
the display of three—dimensional vertically compressed
power spectra, and reduce data to an easily readable
small area of paper display (108-109). Changes in cere-
bral perfusion have been easily identified during carotid
endarterectomy and open—heart surgery with this
method (17,110-114).
The past decade has seen an extraordinary maturation
in the development and employment of sensory-evoked
potentials (115). Sensory-evoked potentials can indicate
the physiological (and often functional) integrity of the
central nervous system areas subserved as the pathways
for these responses. Of the types of sensory-evoked po-
tentials, somatosensory—evoked potentials have been
with us for the longest period of time, being utilized dur-
ing surgery on the spine and spinal cord. Brainstem audi-
tory-evoked potential monitoring is used during poste-
rior fossa explorations, and recording of visual-evoked
potential responses is used during procedures around the
optic chiasm or nerves. Sensory-evoked potential moni-
toring has been used as both a diagnostic and prognostic
modality for (1) patients with spinal cord injuries and
during spinal cord and spine procedures; (2) comatose
patients; (3) determination of brain death; (4) delin-
eation of neoplasms, vascular abnormalities, infarcts,
and other lesions; (5) evaluation of ischernia, hypoxia,
limits of induced hypotension, and anesthesia levels; (6)
evidence of excessive brain retraction; and (7) rnonitor—
ing auditory pathways.
Intraoperatively, better reliability and clinical correla-
tion have been noted with the sornatosensory—evoked
fpotential and brainstern auditory-evoked potential than
"with the visual-evoked potential. Nevertheless, the more
general use of the sornatosensory-evoked potential as an
intraoperative clinical monitoring tool has been limited
because of the level of equipment sophistication, ex-
pense, technical utilization, and methodology necessaiy
and because of a lack of understanding and agreement
concerning correlative signiﬁcance.
Because the somatosensory—evoked potential tells us
only about the condition of the posterior columns, the
integrity of motor function is indirectly inferred. Be-
cause of this critical physiological limitation, the recent
progress in characterizing the rnotor—evoked potential
(MEP) is particularly welcome (116). The use of electro-
magnetic cortical stimulating technology appears to
make the use ofmotor—evoked potential a clinical reality.
Brain Retraction Pressure (BRP)
During intracranial procedures, it is important to as-
sure the brain of an adequate cerebral perfusion pressure
(CPP). In general, this should be about 100 mmHg as, in
the normal brain, autoregulation of the intracranial cir-
culation functions between a mean arterial blood pres-
sure of50 and 150 mmHg (15-17).
In the closed skull CPP = MAP - ICP. Because this is
a global expression of overall perfusion for the whole
brain, it does not indicate regional perfusion pressure
with the skull open and in the area where brain retrac-
tion is taking place (1 17-1 18). We can make this calcula-
tion using
1CPP = MAP — BRP
where rCPP is the regional cerebral perfusion pressure
(in mmHg) and BRP is the measured brain retraction
pressure (in mmHg).
During the past decade, our research group has been
investigating many of the problems associated with the
use of the brain retractor during neurosurgical proce-
dures (119). This work was stimulated in part by the
ﬁndings of Numoto and Donaghy (120), Donaghy and
coworkers (121), and the challenge to design adequate
instrumentation for monitoring brain retraction pres-
sure.
Our animal data (dogs and subhuman primates) indi-
cate that the threshold for retraction injury is related to
the mean arterial pressure, and thus a brain retraction
pressure of 20 mmHg is better tolerated at a mean arte-
rial pressure of 80 mmHg than at a mean arterial pres-
sure of 50 mmHg (122,123). Additional factors inﬂuenc-
ing lesion formation due to brain retraction may be
caused by the intrinsic pharmacologic properties of the
halogenated anesthetics (halothane, enflurane) and
some of the agents used for induced hypotension (tri-
methaphan, nitroprusside, and nitroglycerin) (15,124).
Brain retraction pressure was monitored with a pneu-
rnoelectronic switch built into a thin plastic sleeve into
which the retractor was placed. The unit (Codman Pres-
sure Monitor and Albin-Bunegin Pressure Sensor) cycles
at least 20 times a minute, and on a hard copy of CRT
trace one may even be able to note respiratory fluctua-
tions and vascular pulsations intermixed with the brain
retraction pressure recording.
Our animal data indicate that the brain retraction

ANESTHESIA FOR NEUROSURGICAL PROCEDURES / 11
pressure threshold (for the development of histological
changes after one hour of retraction) at normotensive
[levels was 20 mmHg; at induced hypotension (to a MAP
of 50 mmHg), the threshold dropped to 10 1nrnHg (123).
Following retraction at these threshold levels, changes in
blood—brain barrier permeability, neurological status,
and somatosensory—evoked potentials also occurred
(123). A correlation was also seen between the somato—
sensory—evoked potentials and cerebral perfusion pres-
sure when the brain retraction pressure threshold was
reached. Similarly, a correlation was found between the
cortical blood ﬂow and somatosensoryevoked poten-
tials at brain retraction pressure threshold levels
(123,125).
Our findings concerning the inﬂuence of brain retrac-
tion pressure on the contralateral hemisphere are inter-
esting. We noted that application of 20 mmHg brain
retraction pressure to one hemisphere produced an im-
mediate rise in intracranial pressure of almost the same
order of. magnitude on the contralateral side (123).
Under these conditions, decreases in cerebral blood flow
occurred bilaterally and occurred despite the use ofnitro—
glycerin or trimethaphan (124). Although trimethaphan
is a ganglionic blocker and theoretically does not directly
affect resistance vessels, our studies have indicated that
autoregulation is lost initially as the mean arterial pres-
sure starts to decrease to our end point of 50 mmHg.
This may be a dose—related function because, about 10
minutes after a mean arterial pressure of 50 mmHg is
reached, autoregulation appears to become reestab-
lished. This may have clinical relevance, indicating the
need to avoid retraction for a 10-minute period after
reaching a hypotensive level near 50 mmHg mean arte-
rial pressure. Brain retraction pressures greater than 20
mmHg for one hour (with a mean arterial pressure at 50
mmHg) have been shown to produce a defined infarct in
both subhuman primates and dogs (122).
Our studies of brain retraction pressure in humans
have indicated the importance of a pressure monitoring
tool in the education of neurosurgical residents. As a
rule, initiates to neurosurgery have no "feel" for specific
brain retraction pressure levels and are amazed to dis-
cover how easy it is to approach pressures of 50 mmHg
or higher. After using the brain retraction pressure moni-
tor, they are able to retract adequately using a brain re-
traction pressure not greater than 20 mmHg.
Although the danger ofexcessive brain retraction pres-
sure is obvious with the hand—held retractor, there are
also potential problems associated with the use of me-
chanical retractor holders. We have monitored the ef-
fects of one or more "—inch DeMartel retractors secured
in place by retractor holders during initial exposure of
the operative field. In some instances, the brain falls
away from the retractor, moving its bulk in against the
lateral or opposing portion of the inner table. If this oc-
curs, the retractors are repositioned so that the resulting
brain retraction pressure is less than 20 mmHg. While
the repositioned brain retraction pressure is less than 20
mmHg, a "rebound" often occurs, since the brain has no
more room to move in the cranial vault. Within 10 to 15
minutes the brain retraction pressure can be elevated to
above 30 mmHg as the brain expands against the retrac-
tor. Under these conditions, the retractor should be loos-
ened and, if possible, repositioned at a lower brain re-
traction pressure.
Moss and Price have used changes in BRP to evaluate
the effect of a new anesthetic agent, propofol, on cerebro—
vascular dynamics in the human. They suggest that the
decrease in BRP observed was secondary to the decrease
in CBF which is characteristic of this drug (40).
Because of the difficulties involved in ensuring the
equal distribution of retraction forces on the brain, tre-
mendous shear stresses can be generated at the retractor
edges. During neurosurgical procedures it is important
not to use ridged or deformed retractor blades or those
with sharp edges. Edge pressures can be attenuated by
the use of energy—absorbing material and by better re-
tractor design. Brain retraction pressure should be moni-
tored and, whenever possible, the retractor should be re-
leased periodically. Induced hypotension should be
employed as sparingly as possible. Our aim should al-
ways be to encourage the most adequate regional cere-
bral perfusion pressure possible that is compatible with
surgical exposure and hemostasis.
Electrocardiography
The electrocardiogram (ECG) is important for all neu-
rosurgical cases, and a full complement of arm, limb,
and some chest electrodes should be placed to help de-
fine any ECG abnormalities that may develop. Changes
in rate and wave forms are a sensitive indicator of brain-
stem compression, and ST—T segment changes have been
reported following subarachnoid hemorrhage. Continu-
ous ECG monitoring should be carried out throughout
the intraoperative and postoperative periods (126). New
methods for evaluating myocardial function intraopera-
tively also include transesophageal Doppler—generated
cardiac outputs and transesophageal echocardiography.
Urinary Output
An indwelling urinary tract catheter is extremely im-
portant for following the patient's response to loop di-
uretics and/or hyperosmotic agents as well as for gauging
renal function during prolonged and/or profound hypo-
tension. In addition, estimates of urinary electrolytes
. and osmolality can be easily made.
Chemistries, Blood Gases, and Ventilation
The development of rapid microchemical and polaro—
graphic techniques has made it relatively simple to ob-

12 / CHAPTERI
tain a moment—to—moment metabolic profile. A blood
sample from an arterial line can be analyzed for hemato-
crit, blood gases, Pacoz, Paoz, pH, bicarbonate, calcu-
lated base excess or deficit, colloid oncotic pressure, and
serum osmolality, and values reported within 10 min-
utes after receipt of a sample. Additional values for
serum K", Na", Ca“, ionized calcium, and glucose add
another 10 minutes to the required time. Thus, intraoper—
ative metabolic corrections in acid—base balance and
ventilatory requirements can be made rapidly. Control
of Paooz levels is critical in the management of cerebral
blood flow and intracranial pressure. Tidal volume, min-
ute volume, and airway pressure should be easily ob-
tained from the anesthesia machine and ventilator.
Temperature
An esophageal temperature probe is essential for mon-
itoring this critical parameter. Esophageal temperature is
closely related to undergraduate blood temperature and
is within 1°C of brain temperature, whereas rectal tem-
perature reﬂects that of the body core and may not
change as rapidly as esophageal or tympanic measure-
ments. Prompt recognition of such syndromes as malig-
nant hyperpyrexia cannot be accomplished without this
aid. Patients lose energy and heat under anesthesia, and
body temperatures may fall to levels that increase car-
diac irritability. Keeping a thermal blanket under the
patient to control body temperature and using tempera-
ture—controlled humidifiers during the operation are
worthwhile precautions.
INTRAOPERATIVE MANAGEMENT
Anesthesia Induction and Maintenance
It is usually preferable to place the monitoring cath-
eters before anesthetizing the patient. The exception
may be the patient with an aneurysm, AVM, or elevated
ICP in whom stress or anxiety would be particularly dan-
gerous. Quite often patients come to the operating room
from the intensive care unit with the lines in place. Seda-
tion with a benzodiazepine may be important in the ap-
prehensive and/or hypertensive patient with a vascular
lesion in order to avoid a rebleed.
An induction technique should (1) not decrease intra-
cranial compliance; (2) minimize decreases in cardiac
output and peripheral vascular resistance; (3) preclude
arterial hypertension and tachycardia due to intubation;
(4) ensure adequate muscle relaxation; and (5) avoid
coughing and "bucking" that can challenge intracranial
compliance as well as the integrity of an aneurysm. For
these reasons, the technique we use consists of preoxy—
genation with 100 percent 02 by face mask followed by
titrated boluses of fentanyl or sufentanil citrate to which
a benzodiazepine such as rnidazolam may be added. It
cannot be emphasized too strongly that the fluid—re—
stricted neurosurgical patient is often markedly hypovo—
lemic with both decreased plasma volume and red cell
mass and increased antidiurectic hormone and catechol—
amine levels. Hence, severe hypotension can occur dur-
ing induction, especially when the thiosubstituted barbi-
turates are used because they affect myocardial
contractility. For this reason, we generally infuse 6 per-
cent hetastarch in 0.9 percent sodium chloride as soon as
an intravenous line is secured. A colloid oncotic pressure
(COP) less than 15 mmHg is worrisome and necessitates
the use of plasma volume expanders. Anesthesia is pro-
duced by a slow intravenous injection of about 3.0 to 6.0
mg/kg of thiopental or thiamylal, the injected dose of
barbiturate being titrated to changes in arterial pressure.
Vecuronium bromide, a nondepolarizing muscle relax-
ant that does not produce histamine release and causes
minimal cardiovascular instability, is injected intrave-
nously at an approximate dose of 0.08 to 0.1 mg/kg. In
the elective case, we generally do not use succinylcholine
because of the problems of hyperkalemia and cortical
activation with the latter possibly increasing cerebral
blood ﬂow and hence intracranial pressure in the face of
decreased intracranial compliance. A peripheral nerve
stimulator is used with the electrodes placed over the
ulnar nerve distribution at the wrist. The complete ab-
sence of twitch after stimulation indicates neuromuscu—
lar blockade.
To attenuate coughing and bucking on endotracheal
intubation, 1.5 mg/kg of cardiac lidocaine (no preserva-
tive) is injected intravenously. Lidocaine also has the ef-
fect of transiently decreasing cerebral blood ﬂow and ce-
rebral oxygen uptake. An armored (wire spiral) silicone
rubber endotracheal tube with a low—pressure cuffis in-
serted under laryngoscopy, and the patient is placed on a
volume—cycled anesthesia ventilator with the ventilation
controlled to obtain a Paoz above 100 mmHg and a
Pacoz of 25 to 35 mmHg. As soon as the surgical posi-
tion is secured, an arterial blood sample is taken and
examined for blood gases, electrolytes, hematocrit, he-
moglobin, and COP. Maintenance of anesthesia is
carried out with an oxygen—air mixture, fentanyl or su-
fentanil infusion, and the addition of isoflurane in an
inhaled concentration generally not exceeding 1 percent.
It is our practice not to use N20 because of its tendency
to increase CBF and decrease CMRO2. When the sitting
position is used, we generally use 100 percent 02, eli1ni—
nating the air mixture. Although propofol has just re-
cently been released in the United States, its use in neur-
oanesthesia has become popular in the United Kingdom
where it is used both for induction and maintenance be-
cause of its ability to decrease CBF and CMRO2, its
rapid turnover, and the resulting quick emergence of the
patient from anesthesia.

ANESTHESIA FOR NEUROSURGICAL PROCEDURES / 13
Induced Hypotension
This is a technique primarily used in neurovascular
procedures involving aneurysms, AV malformations, or
vascular tumors where the need to reduce intravascular
tension is critical. Interestingly, the use of the operating
microscope and induced hypotension were responsible
for a marked decline in the utilization of hypothermia
during neurovascular procedures in the 1960s and early
1970s. The advent of the temporary clip and the realiza-
tion that induced hypotension (together with brain re-
traction) can reduce effective cerebral perfusion below
autoregulatory levels and trigger cerebral vasospasm
have more recently reduced the use of induced hypoten-
sive techniques.
As noted in the introduction to this chapter, the use of
hypotension in neurosurgery was first reported in 1906
by Victor Horsley, who reduced blood pressure in the
face of hemorrhage by using an increased concentration
of chloroform (6). In 1917, Harvey Gushing observed
that hemorrhage was followed by vasoconstriction,
which led to a dry operating field.
Up until the mid—1970s, the most common ganglionic
blocking agent in use was trimethaphan. Probably owing
to its rapid destruction by pseudocholinesterase, this
drug has the advantage that its action can be precisely
controlled. Certain side effects, namely tachycardia,
tachyphylaxis, inactivation of the pupillary reﬂex,
curare—like action, and histamine release are drawbacks
to its use. The last of these has the potential to increase
intracranial pressure by causing cerebral vasodilation ei-
ther directly or indirectly by inducing bronchospasm
and thereby raising Pacoz. It has been shown that tri-
methaphan can be as deleterious to cerebral metabolism
as acute hemorrhage (127). Deep halothane anesthesia
will also produce hypotension, primarily by direct myo-
cardial depression and a subsequent fall in cardiac out-
put. Halothane has also been shown to cause the loss of
cerebrovascular autoregulation, to raise intracranial
pressure, to augment experimentally induced edema of
the cerebral cortex and, at concentrations above 2.3 per-
cent, to produce cerebral lactic acidosis even when oxy-
genation is adequate (15,128).
Sodium nitroprusside, acting directly on the vessel
wall, is considered by many to be the agent of choice for
induction of controlled hypotension because of its abil-
ity to easily affect blood pressure moment—to—moment
and its apparent lack of tachyphylaxis. However, one
must be cognizant of its potential for harm owing to
cyanide toxicity, its ability to increase intracranial pres-
sure, and its possible role in the loss of autoregulation if
blood pressure is lowered too rapidly (15,129—132).
Although nitroglycerin, or glycerin trinitrate, has been
part of the medical armamentarium for over 100 years,
its first intravenous use during neurosurgery was not re-
ported until 1969 (133). The action of this drug is pri-
marily exerted on the capacitance vessels and, in contra-
distinction to sodium nitroprusside, increases ﬂow to
ischemic myocardium and improves left ventricular
function without marked acceleration ofheart rate. Intra-
venous nitroglycerin has been used to control blood
pressure during elective neurosurgical procedures such
as the clipping of intracranial aneurysms, resection of
arteriovenous malformations or vascular intracranial tu-
mors, and microneurovascular decompression of cranial
nerves (132,134). Like nitroprusside, nitroglycerin af-
fects autoregulation and can produce increases in intra-
cranial pressure. Nitroglycerin has a slower onset of ac-
tion, and it appears that there may be greater resistance
to its hypotensive effect when compared to nitroprus-
side. Because of its low toxicity and positive effects on
coronary circulation, we first use nitroglycerin for in-
duced hypotension (with the skull open) and then, in the
event of tolerance, move to sodium nitroprusside.
Other drugs used as induced hypotensive agents in-
clude labetalol, a combined alpha— and beta—adrenergic
blocker; captopren, a renin antagonist; and esmolol, an
ultrashort—acting beta blocker. Other drugs being studied
include adenosine (135,136) and adenosine triphos—
phate. The use of high concentrations of the inhalational
agent isoﬂurane to induce hypotension during aneu-
rysmal clipping has also been described (137). Unlike
halothane and enﬂurane induced hypotension, cardiac
output and cerebral blood ﬂow with isoflurane are well
maintained, as the hypotension is due to peripheral va-
sodilatation(134,137).
Rebound arterial hypertension has been reported after
termination of nitroprusside infusion and has been
found to be due to activation of the renin—angiotensin
system. Propranolol (as a renin antagonist) has been
used prophylactically prior to the use of nitroprusside to
attenuate this response (131).
Induced hypotension should not be attempted with-
out an arterial line, ECG, and the capability to monitor
urinary output continuously. The use of a central venous
pressure line or Swan—Ganz catheter is also of aid in de-
lineating the cardiovascular responses (57,58).
During aneurysm or arteriovenous malformation sur-
gery, an adequate number of transfusion units should be
available in or adjacent to the operating room. At least
two large—bore intravenous catheters should be in place
for transfusion routes, and they should be kept open.
Regardless of the choice of agent for induced hypoten-
sion, the patient must have an adequate circulating
blood volume prior to hypotension, because oligemic
hypotension adversely affects cerebral metabolism. The
hypotensive drug should be delivered by means of a cali-
brated system, whether a microdrip infusion set or an
infusion pump. The timing and depth of induced hypo-
tension depend on surgical factors and the general condi-
tion of the patient. Because the purpose of hypotension
is to reduce the arterial transmural pressure, it may be

CHAPTER 1
reasonable in many instances to start dropping the intra-
aitaial pressure 15 or 20 mmHg with the opening of the
dura. Many neurosurgeons ask that controlled hypoten-
sion begin as soon as the aneurysmisbroughtinto view
and continue until after clipping. Some surgeons request
that the mean arterial pressure be brought to a certain
level (e—g.. 40 to 50 mmHg mean arterial pressure) and
kept there until after clipping. A physiological approach
would allow one to reduce the mean aiterial pressure to a
levelatwhichintravascularpressureisreducedwithin
the aneurysm itself, with the physiological constraints of
the patient always kept in mind.
After the need for induced hypotension has passed,
arterial pressure should be restored gradually without the
administration of vasopressors, especially in patients
whose autoregulation is compromised. In these individ-
uals, cerebral blood ﬂow passively follows aiterial pres-
sure surges, and intracranial pressure may increase.
Cerebro vascular Ischernic Disease (138,139)
The preoperative assessment is especially important
for individuals who are candidates for carotid endarterec-
tomy. since many of these patients have multiple system
problems. It is not unusual to find a candidate for carotid
endarterectomy who has a history of arterial hyperten-
sion, coronary artery disease, diabetes mellitus, and
chronic obstructive pulmonary disease. Many of these
patients are taking multiple medications; it is not un-
common to encounter someone taking two antihyper—
tensives, a calcium channel blocker, nitroglycerin, and a
diuretic.
Cardiovascular, pulmonary, and renal assessment
should be completed and extant arterial hypertension
should be under medical control, always realizing that
cerebral autoregulation may be shifted to the right, ne-
cessitating a higher cerebral perfusion pressure. Si1ni—
larly, diabetes should be under good medical 1nanage—
ment, because the brain already at cerebrovascular risk
does not tolerate either the hypoglycemic or hyperglyce-
rnic state. Following myocardial infarction, elective ca-
rotid surgery should be postponed for at least six
months.
In general, the preoperative medication should be
light, because drugs with a long half—life might confuse
the postoperative neurological evaluation. This is espe-
cially true for patients undergoing carotid endaiterec—
tomy under regional anesthesia, since they need to be
able to cooperate in the ongoing neurological evaluation.
The choice of regional or general anesthesia lies, for
the most part, in the hands of the neurosurgeon and de-
pends on his or her experience. Modifying factors may
include the duration of the procedure and patient rnoni—
toring. Procedures calculated to take more than two and
one—half hours should not be done under regional anes-
thesia because the patient becomes uncomfortable and
may move. Also, the duration ofthe local anesthetic may
become a problem. On the other hand, regional anesthe-
sia may be preferred if electroencephalographic moni-
toring is not available. In terms of regional anesthetic
technique, we block both the superficial and deep cervi-
cal plexus, injecting the second, third, and fourth cervi-
cal nerves of the operative side.
Although the anesthetic technique for providing gen-
eral anesthesia is important, equally important are the
criteria on which control of the physiological parameters
and the type ofmonitoring employed are based. In partic-
ular, the neurosurgeon and the anesthesiologist must
agree on the arterial blood pressure to be maintained
prior to induction. This "number" may approximate a
resting preoperative ﬁgure, but it is a dynamic figure in
that it may need to be upgraded during cross—clainping
or when there are neurophysiological indications that
the brain is becoming ischernic. In order to increase or
decrease arterial blood pressure at a moment's notice,
the necessaiy vasopressors and vasodilators must be at-
tached to a venous access (with a short dead space) for
rapid delivery by an infusion pump.
In our institution, we routinely employ an indwelling
arterial line for direct arterial pressure measurements, an
automatic cuff blood pressure monitor on the contralat—
eral arm, and a central venous line inserted via the anti-
cubital fossa into the superior vena cava proximal to the
right atrium. The central line is used for ﬂuid infusion as
well as for measuring central venous pressure. Neuro-
muscular blockade is monitored with a nerve stimulator,
and urinary output is collected via a Foley catheter that
is inserted after induction of anesthesia. We also rou-
tinely employ an esophageal stethoscope and tempera-
ture probe, continuous electrocardiography, a mass spec-
trometer, and a pulse oxirneter. In patients with severe
cardiovascular compromise, we do not hesitate to e1n—
ploy a trip le—lumen Swan—Ganz balloon catheter. Evalua-
tion of cerebral function is carried out using continuous
monitoring of the processed EEG. The EEG electrodes
are applied prior to induction of anesthesia so that an
awake tracing can be made for baseline comparison.
Induction of anesthesia is preceded by preoxygenation
and consists of an intravenous injection of sufentanil or
fentanyl, followed by intermittent boluses of thiopental.
Laryngoscopy and intubation are accomplished with a
nondepolarizing muscle relaxant such as vencuronium
bromide and facilitated by the intravenous bolus injec-
tion of 1.5 mg/kg of lidocaine just prior to endotracheal
tube placement. Our anesthesia maintenance technique
involves controlled ventilation at a normal Pacoz, oxy-
gen—air inhalation, and an intravenous infusion of sufen-
tanil or fentanyl and thiopental. Unusual blood pressure
surges may be managed with isoflurane (up to 1 percent).
Sustained arterial hypertension is addressed by a nitro-
glycerin or nitroprusside infusion, and hypotension by

ANESTHESIA FOR NEUROSURGICAL PROCEDURES / 15
phenylephrine. We have used 5.0 mg boluses of labeta—
lol, an antihypertensive agent that contains both alpha
and beta blockers, with good success. Labetalol has also
proven efficacious in managing the postoperative hyper-
tension seen during and after extubation. The ultra-
rapid—actmg beta blocker, esmolol hydrochloride (half-
life of 9 minutes) can also be effective in treating
hypertension and tachycardia; it is given by a titrated
infusion. Prior to clamping, the physiological data are
reviewed, and blood pressure is elevated if it has fallen
below the agreed—upon level.
After termination of the endarterectomy, the muscle
relaxant is reversed, inhalational and intravenous agents
are stopped, and the endotracheal tube is removed as
long as there are clear indications of adequate ventila-
tion. Arterial pressure is monitored continuously during
movement from the operating room to the recovery
room, and we do not hesitate to ensure blood pressure
stabilization in the operating room prior to movement.
Posterior Fossa Surgery
The pons and medulla contain critical cardiovascular
and pulmonary centers, cranial nerve exit zones, and
relay stations for major motor and sensory tracts. Thus,
traction, retraction, tissue removal, shifts in blood vol-
ume, hypoxia, and blood gas fluctuations may provoke
serious cardiorespiratory changes. For all these reasons,
careful intraoperative monitoring is essential in the man-
agement of these cases.
In terms of anesthesia care, the essential problems as-
sociated with posterior fossa surgery relate to the fact
that most cases are carried out in the sitting position. The
hazards relating to the sitting position are concerned
with the problems of hypotension, adequate cerebral
j perfusion pressure, and venous air embolism. Although
these areas have been covered in a previous section, it is
worthwhile to reiterate that the very poor—risk and the
elderly patient should not be operated on using the sit-
ting position because of the stresses on the cardiovascu-
lar and cerebrovascular systems. Volume—depleted pa-
tients offer a considerable risk of hypotension and
inadequate cerebral perfusion unless corrected prior to
and during induction of anesthesia. In all cases in which
the sitting position is employed, the patient should be
monitored with an arterial line, central line for air aspira-
tion and measurement of central venous pressure, ultra-
sonic Doppler air bubble detector, ECG, esophageal
stethoscope and temperature probe, pulse oximeter, and
a mass spectrometer providing continuous end—expira—
tory CO2 analysis. The arteiial blood pressure transducer
should be referenced at the superior margin of the inci-
sion and not at heart level in order to mark the cerebral
perfusion pressure truly. Nitrous oxide should be
avoided because of its role in increasing air bubble vol-
ume and its contribution to tension pneumocephalus.
The Valsalva maneuver should be used cautiously, and
the application of positive and expiratory pressure is
probably contraindicated because of its ability to change
the transatrial pressure gradient which may allow the
passage of air into the left heart via a patent foramen
ovale, thus producing paradoxical air embolism. In the
event air is entrained, the patient should be placed on
100 percent oxygen and the neurosurgeon notified so
that the operative field can be flooded with saline and the
source of air aspiration identiﬁed. The anesthesiologist
should immediately aspirate the central line and remove
as much air as possible. Changes in vital signs should be
treated symptomatically and if hypotension, arrhyth-
rnias, or cyanosis persists, the patient should be immedi-
ately changed from the sitting position to the supine. In
the event the patient awakens with a focal deﬁcit or can-
not be awakened, computerized axial tomography
should be done. The presence of intracranial air indi-
cates that paradoxical air embolism has occurred; the
only definitive treatment is hyperbaric oxygenation.
The Sitting Position and Spinal Cord Injury
The development of quadriplegia following surgery in
the sitting position was described by Hitzelberger and
House in 1980,Kurzein 1981, and Wilder in 1982(140—
142). Hickey and coworkers demonstrated the close par-
allel between autoregulation of spinal cord and cerebral
blood ﬂow (17). These findings emphasize the need to
consider spinal cord perfusion pressure along the same
lines as cerebral perfusion pressure. The gradient be-
tween a plane passing across the fourth intercostal space
and the spinous process of the fourth cervical vertebrae
can measure as much as 20 cm. If the arteiial transducer
reference point is keyed to the heart level and a mean
arterial pressure of 60 mmHg is noted, the effective spi-
nal cord perfusion pressure at the C4 level will essentially
be 60 mmHg minus 20 mmHg, or about 40 mmHg,
which is below the lower limits of autoregulation and is
capable of producing spinal cord ischemia if sustained
for any period of time. This can also be exacerbated by
the fact that blood ﬂows from the opposite ends of the
spinal cord via the cervical cord vessels and the paired
posterior and anterior spinal arteries. Thus, the so—called
watershed areas can be found at equidistant points from
the radicular artery bifurcations. Therefore, the lower
cervical area, being farthest from collateral pathways,
would appear to be the most vulnerable to ischemia
(143,144). In addition, Turnbull and coworkers have
noted, in autopsy material, that it is common for only
one anteiior radicular arteiy to supply the cervical cord
(145). Fried, Doppman, and DiChiro collected three hu-
man spinal cords that all showed a paucity of radicularl
aiteries (144). Mannen noted, in apostmortem review of
215 spinal cords, that 45 had only one anterior radicular
artery in the cervical cord (146). The clinical signiﬁcance

16 CHAPTER 1
ofthe cervical "watershed" can be seen in Jellinger's anal-
ysis of the distribution of chronic, ischernic cord lesions
in 60 cases of advanced arteriosclerosis (147). He noted
that the preferential area of ischemia was located be-
tween C5 and T2. In his postmortem review, Mannen
described 25 spinal cord infarctions in geriatric cases
where the selective site for small softening was at the C5
to C8 levels, with the greatest number of infarcts being at
C6 (146). The rhesus monkey study of Fried, Doppman,
and DiChiro demonstrated that the area most vulnerable
to ischemia would be at C6 because the blood flow splits
into compartments ﬂowing up and down the anterior
spinal artery (144). Thus, the lower cervical area would
be farthest from the collateral pathways (via the vertebral
and intercostal arteries). Again, this points out the
danger of allowing arterial hypotension to continue for
any sustained period of time, as well as the hazard of
manipulating the head and neck during positioning into
the sitting position without being able to monitor the
neurologic status of the patient. Ernst and coworkers
noted changes in cervical spinal cord blood ﬂow in ani-
mals with increased intracranial pressure placed in the
sitting position (148). All the precautions taken for poste-
rior fossa explorations in the sitting position should also
be cariied out during these procedures on the spine or
spinal cord.
POSTOPERATIVE CARE
The same meticulous standards observed during sur-
gery, in terms ofmonitoring equipment, ventilatory facil-
ities, physician surveillance, and caliber of nursing per-
sonnel, must prevail during the postoperative period as
well. The problems encountered postoperatively gener-
ally necessitate the same kinds ofinformation processing
and control. It is convenient for monitoring equipment
to be standardized in the operating room, recovery
room, and neurosurgical continuous care unit so that the
patient can be moved from one location to another with
the same transducers. An infusion pump with a hypoten-
sive agent should be available in case the patient be-
comes hypertensive. Upon the patient's arrival at the re-
covery room or intensive care unit, the following tests
should generally be made: portable chest film; ECG;
blood gases; serum electrolytes, glucose, and osrnolality;
hematocrit and hemoglobin; and urine output. The pa-
tient should be followed with periodic blood gas measure-
ments and evaluated frequently by the anesthesiologist
responsible for the preoperative and operative rnanage-
ment. The continuum of care should be maintained un-
til the patient's physiological responses have stabilized.
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20. Smith AL, Marque J J . Anesthetics and cerebral edema. Anesthesi-
ology 1976;45:64—72.
21. Fitch W, McDowal DG. Effect of halothane on intracranial pres-
srue gradients in the presence of intracranial space-occupying le-
sions. BrJAnaesth 1971;43:904-911.
22. Miletich DJ, Ivankovich AD, Aldrecht RF, et al. Absence ofauto-
regulation of cerebral blood ﬂow during halothane and enﬂurane
anesthesia. Anesth Analg 1976;55:100-109.
23. Sakabe T, Maekawa T, Fuji S, et al. Cerebral circulation and
metabolism during enﬂurane anesthesia in humans. Anesthesiol-
ogy 1983;59:532-536.
24. Myers RR, Shapiro HM. Local cerebral metabolism during en-
ﬂurane anesthesia: Identification of epileptogenic foci. Electroen-
cephalogr Clin Neurophysiol 1979;47:153-162.
25. Newberg LA, Milde JH, Michenfelder JD. The cerebral meta-
bolic effects of isoﬂtuane at and above concentrations that sup-
press cortical electrical activity. Anesthesiology 1983;59:23-28.
26. Manohar M, Parks C. Regional distribution ofbrain and myocar-
dial perfusion in swine and during 1.0 and 1.5 MAC isoﬂurane
anesthesia produced without and with 50 percent nitrous oxide.
Cardiovasc Res 1984; 18:344-353.
27. Grosslight K, Colohan A, Bedford RF. Isoﬂurane anesthesia-risk
factors for increases in ICP. Anesthesiology 1985;63:533-536.
28. Albin MS, Bunegin L, Gelineau J . ICP and CBF reactions to
isoﬂurane and nitrous oxide during normocarbia, hypocarbia,
and intracranial hypertension. In: Miller JD, Teasdale GM,
Rowan JO, Galbraith SL, Mendelow AD, eds. Intracranial Pres-
sure VI. Berlin: Springer-Verlag, 1986;719-724.

CHAPTER 2
PrinE%'ples 0fNeur0sur ery,
edit by Robert G. rasonan Rsttcsberf *; FWL
Published bv Raven Press, LaL, Nc* Voft.
Primary Diseases of the Skull
John P. Laurent
Granulomatous, 21
Histiocytosis X, 21
Osseous, 21
Fibrous Dysplasia, 21
Orbital Dysplasia, 21
Osteoina, 22
Ossifying Fibroina, 22
Osteoid Fibroina, 22
GRANULOMATOUS
Histiocytosis X
Histiocytosis X is a group of three reticuloendothelial
diseases involvingbone (1). Eosinophilic granuloina, the
most common, usually appears as a single lesion in the
skull of a cl1ild four to seven years of age. The lesion
causes localized pain, erytheina, and swelling, and it may
be confused with a local infection. Radiographs will dem-
onstrate a lytic lesion with a punched—out, nonsclerotic
border. Excisional biopsy is recommended and curative
of a single lesion. When the diagnosis is confirmed and
multiple bony lesions are present, low—dose radiation
(400 to 600 rads) will effectively eradicate the remaining
lesions.
Visceral reticuloendothelial involvement and nu1ner—
ous calvarial lesions in an infant are called Letterer—Siwe
disease. The prognosis is poor with extensive visceral in-
volvement.
Han—Schuller—Christian disease is characterized by re-
ticuloendothelial involvement at the skull base and hypo-
thalamus in the older child. Symptoms may include dia-
betes insipidus, dwaifism, exophthalinos, and multiple
skin lesions. The prognosis depends on the extent of
non—neural involvement but appears better than in let-
terer—Siwe disease.
J. P. Laurent: Section ofPediatric Neurosurge1"y, Baylor Col-
lege of Medicine, Houston, Texas 77030.
21
Vascular, 22
Heinangioina, 22
Aneurysinal Bone Cyst, 22
Neoplastic, 22
Sarcoma, 22
Chondroina, 22
Chordoina, 22
References, 23
OSSEOUS
Fibrous Dysplasia
Fibrous dysplasia is a common bony inesenchyinal
lesion of both the skeleton and cranial vault with onset in
childhood or adolescence. Progression of the lesions oc-
curs during periods of skeletal growth, later followed by
ossification. The inonostotic form involves a single
bone, and the polystotic form involves multiple bones.
Albright's disease is a variation ofpolystotic fibrous dys-
plasia and manifests extraskeletally in the form of skin
piginentations, sexual precocity, and endocrine dysfunc-
tion (2). The histologic picture is distinctive, with dys-
plastic bone in abundant collagen. Neurologic sy1np—
toms are related to neural compression and foraininal
entrapment, and they primarily involve the orbital, pe-
trosal, and sellar areas.
Radiographs demonstrate areas of hyperostosis with
mixed lucent and sclerotic margins. Three—di1nensional
computerized tomography (CT) is extremely helpful
prior to surgical excision. Because hormonal, medical,
and radiation treatments have been unsuccessful, total
en—bloc resection of the dysplastic area causing neural
compression should be attempted. Sarcoinatous degen-
eration can occur following radiation treatment.
Orbital Dysplasia
Unilateral absence of the greater wing of the sphenoid
(orbital dysplasia) is diagnostic of von Recklinghausen's

22 / CHAPTER 2
disease. Prolapse of the temporal lobe into the orbit
causes severe exophthalmos. Plexiform neurofibroma of
the ciliary nerve and exophytic optic glioma should be
differentially considered. A three—dimensional bone win-
dow CT scan is exceptionally helpful in planning surgi-
cal reconstruction of the sphenoid wing. Enophthalmos
is a postreconstruction complication.
Osteorna
An osteorna is abenign bone tumor, more common in
adults than in children, that arises from the outer diploe
of the skull. Lesions are frequently found in the nasal or
mastoid sinuses. Skull osteomas are hard, painless
masses. Osteomas, soft tissue tumors, and colonic pol-
yposis form a triad of symptoms known as Gardner's
syndrome. Radio graphs of osteomas appear as thickened
bone with variable lucency. Proptosis, sinus obstruction,
and cosmetic deformity are the primary indications for
complete surgical removal of these tumors.
Ossifying Fibroma
Ossifying fibromas are similar to both fibrous dyspla—
sia and osteomas in histologic appearance. The clinical
presentation depends on the primary location, which
will be either mandibular or in the maxillaiy sinuses.
Distortion and local neural compression may Cause
symptoms. Radiographically, ossifying fibromas appear
as well—de1narcated, thin—shelled bone with sclerotic ar-
eas. Total surgical excision is mandatory because these
lesions may recur locally and malignant changes may
take place.
Osteoid Fibroma
Osteoid fibroma tumors are rare and are seldom seen
in the skull. Severe local pain differentiates an osteoid
fibroma from an epidermoid cyst, which will have a simi-
lar appearance radiologically (see Chapter 8). Treatment
of this tumor requires en—bloc resection.
VASCULAR
Hemangioma
Hemangiomas of the cranial vault are rare, are seldom
symptomatic, and commonly cause cosmetic concern.
Originating in the diploe, they expand outward while the
periosteum and inner table remain intact. The etiology is
unknown. Radiographically, hemangiomas appear as lu-
cent, honeycombed bone with nonsclerotic margins. Ex-
cisional biopsy is recommended because radiation ther-
apy is unsuccessful.
Aneurysmal B011e Cyst
J affe and Lichtenstein described an aneurysmal bone
cyst in 1942 as a benign cystic bone lesion (3). Although
aneurysmal bone cysts rarely involve the skull, they have
been found in the frontal, parietal, and temporal areas
(4). The origin of this tumor remains unknown. The rap-
idly enlarging, tender mass demonstrates characteristic,
though not diagnostic, radiologic features. Skull roent-
genograms may show a lesion with a typical soap—bubble
appearance involving both tables and occasionally ex-
panding i11tracranially. Angiography will clarify the vas-
cular etiology. A CT scan will reveal an enhancing le-
sion. Histologically, the bone channels are lined with a
single layer of endothelium, and new bone formation,
giant cells, and hemosiderin—laden histiocytes are evi-
dent. En—bloc surgical removal is curative and is recorn—
mended to decrease the possibility ofposttraumatic hern-
orrhage.
NEOPLASTIC
Sarcoma
Sarcomas of the skull are extremely rare. They may be
confused with intradiploic or extracranial invasive me-
ningioma on presentation. The rapid increase in size of
sarcomatous lesions aids in the differential diagnosis.
Surgery, radiation, and chemotherapy postpone the even—"
tual fatal outcome.
Chondroma
Synchondrotic chondroma is regarded as the histologi-
cally benign version of chordoma and commonly occurs
at the skull base arising from junctional synostotic areas.
Nasal chondroma arises from the paranasal sinuses.
Symptomatology depends on location. Although pro gres—
sion is usually slow, malignant degeneration can occur.
In Ollier's disease, other skeletal areas are involved in the
chondromatosis. Slow invasion and compression of
neural structures produce significant neurologic syrnp—
toms. Because the tumor is radiation—resistant and recur-
rence at operative sites is common, this benign, slow-
growing tumor is often fatal.
Chordoma
Thought to derive from notochordal elements, chor-
domas are aggressive tumors that arise at the cranial
base, destroying the clivus and sella and expanding to-
ward the nasopharynx to compress the brain stem. Al-
though the rnaj ority of chordomas in children are intra-
cranial, they usually occur in the sacral region in adults

(5). When the tumor is located intracranially, diplopia is
the most common complaint, followed by cranial nerve
dysfunctnon due to tunnor ccunpwessnon ofthe bran)
stem. The tumor may metastasize, usually to the lungs,
with eventual fatal outcome.
Chordomas occasionally show fine, stippled calciﬁcation
on plain skull radiographs. Magnetic resonance imaging
(MRI) is particularly useful in localizing the tumor.
Radical surgical decompression of the clival tentorial
area is not curative but is effective as the primary treat-
ment. Radiation therapy may be useful. Long—term sur-
vival in children is possible although the average survival
time is four to seven years. Chordomas should not be
confused wdﬂisynchondrouc chondnnnas ofthe anne
area. Chondromas are the benign variant of the noto-
chordalangle(6)
PRIMARY DISEASES OF THE SKULL / 23
REFERENCES
l. Crocker AC. The histiocytosis syndromes. In: Vaughan NC, McKay
I R, Behrman RE, eds. Nelson Textbook of Pediatrics, llth edition.
Philadelphia, WB Saunders, 1979,1983.
2. Albright E, Butler AM, Hampton AO. Syndrome characterized by
osteitis fibroses disseminata, area of pigmentation and endocrine
dysfunction with precocious puberty in females. N Engl J Med
l937;2l6:727—730.
3. Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with empha-
sis on roentgen picture, pathologic appearance and the pathogene-
sis. Arch Surg l942;44:l004—l025.
4. Cataltepe O, Inci S, Ozcan OE, Saglam S, Erbengi A. Aneurysmal
bone cyst of the frontal bone. Surg Neural 1990;33:391-394.
5. Wold LE, Laws ER. Cranial Chordomas in children and young
adults. J Neurosurg 1983;58:602-606.
6. Faulroner MA, Baily lC, Ducker LW. Surgical treatment ofchordo—
mas and Chondromas of the skull base. J Neurosurg 1968;29:261-
265.

CHAPTER 3
Princi les 0fNeur0surgery,
edrte by Robert G. Grossman. Rosenberg © 1991.
Published by Raven Press, Ltd., New York.
Congenital and Developmental
Cranial Abnormalities
John P. Laurent and William R. Cheek
Closure Defects of the Neuroepithelial Ectoderm, 25
Scalp Defects, 25
Skull Defects, 25
Cephaloceles, 26
Dermal Sinus Tracts, 27
Epiderrnoids and Dermoids, 28
Congenital I11tracra11ial Cysts, 29
Developmental Cysts, 29
Colloid Cysts, 30
CLOSURE DEFECTS OF THE
NEUROEPITHELIAL ECTODERM
Scalp Defects
Congenital ulcers of the scalp, or aplasia cutis congenita,
may occur in the newborn without the presence of other
intracranial abnormalities. Most such defects are located
in the parietal area, vary in size, and may be multiple.
When the skull is absent, the base of the defect may ex-
tend to the subarachnoid space. A parchrnent—like, moist
membrane covers the area, but there is no underlying
supporting structure.
The pathogenesis of the lesion has been postulated to
be pressure necrosis during labor, amniotic adhesions
with tearing of the skin, arrest of rnidline development,
or defective neural tube closure. Incomplete fusion of
the mesoderm, along with localized arrest of ectodermal
development, is the most logical theory. A midline occip-
ital location is typical. Hydrocephalus, arhinencephalia,
and rnidline defects are the most commonly associated
congenital abnormalities.
Other lesions that may be confused with congenital
J. P. Laurent and W. R. Cheek: Section of Pediatric Neuro-
surgery, Baylor College of Medicine, Houston, Texas 77030.
25
Congenital Intracranial Tumors, 31
Harnartornas, 31
Teratornas, 32
Lipornas, 32
Miscellaneous Developmental or Congenital
Abnormalities, 32
Phakornatosis, 32
Sinus Pericranii, 32
References, 33
absence of skin are obstetric trauma to the scalp, congeni-
tal lues, small encephaloceles, and ectopic brain tissue.
Most of the defects, even those up to 10 cm, heal sponta-
neously. Defects over the sagittal sinus may be life threat-
ening, however, and an early full—thickness skin graft
may be necessary. The greatest period of danger in neo-
nates extends from birth to eight days. Many defects do
not heal completely and require surgical repair. If dura is
exposed at the defect, a full—thickness skin pedicle graft is
needed; otherwise, split—thickness grafts can be made.
Closure of the bony defect is seldom necessary.
Skull Defects
Fusional defects can prevent complete closure of the
skull. Ossiﬁcation defects can occur. If the scalp is also
absent, the prognosis is worse, and surgical repair and
skin grafting are needed to prevent hemorrhage or infec-
tion. Cranioplasty, if indicated, should not be done until
the child is three or four years old.
The most common congenital defect is bilateral pari-
etal forarnina located at the parietal emissary veins.
Many such defects are incidental discoveries in routine
skull radiographs. The defect is surrounded by a beveled
nonsclerotic rim of bone and is filled with fibrous tissue.
This defect is not clinically important, and cranioplasty
is seldom indicated (Fig. 1).

26/CHAPTER3
FIG. 1 . Congenital bilateral parietal foramina seen on a skull
radiograph.
In children with pulsating exophthalmos and protru-
sion of the temporal bone who show no other neurologic
signs or symptoms, a congenital defect of the sphenoid
bone may be present. This disorder is frequently asso-
ciated with neuroﬁbromatosis. In most children, early
complaints can be related to exophthalmos. Agenesis of
the sphenoid bone causes temporal bulging. Although
exophthalmos does not progress after the skull ceases to
grow, cosmetic surgery to correct the deformity may be-
come necessary.
Epicranial arachnoid cysts and ectopic glial tissue oc-
casionally appear as masses at the obelion, and in most
patients an underlying skull defect is present. A fibrous
stalk extends to the dura, and dermoid elements may be
present. Surgical removal of these lesions is necessary
and will usually correct the problem.
"Craniolacunia," "Luckenschadel," and "beaten
silver" are terms used to describe a characteristic radio-
logic appearance with patchy thinning of the cranial
vault, which, in the newborn, is often confused with 11or—
mal convolutional markings. Lacunar skull is com-
monly associated with myelomeningoceles and enceph-
aloceles. There is no correlation between cranio—
lacunia and hydrocephalus or increased intracranial
pressure. Lacunar skull occurs in the parietal area and is
caused by a mesenchymal developmental disturbance
with delayed ossifrcations. Reestablishment of normal
bone ossification begins shortly after birth, and a normal
skull pattern can be seen by three months of age.
Cleidocranial dysostosis and osteogenesis imperfecta
are the result of a generalized mesenchymal connective
tissue failure at ossification sites of the cranial vault.
Cleidocranial defects are predominantly midline defects,
consisting of absent clavicles and failure of the cranial
sutures to close normally. Mosaic involvement, particu-
larly of the parietal bones, is characteristic of osteogene-
sis imperfecta. Neurosurgical intervention is not indi-
cated for these mesenchymal skull abnormalities.
Cephaloceles
A congenital cephalocele is an extracranial protrusion
of the leptomeninges, with or without cerebral tissue,
through a defect in the cranial bones. Meningoceles are
protrusions without brain tissue; encephaloceles contain
brain. The most common location of cephaloceles in pa-
tients of European or American ancestry is occipital,
with a frequency of less than 1 in 1,000 live births. The
incidence is higher in patients of Southeast Asian extrac-
tion, in whom the lesions more commonly occur in the
frontal ethmoidal area. The embryologic events leading
to the disorder are unknown. The most widely accepted
theory holds that during the embryonic stage, lack of
separation of the brain, dura, and skin results in a defect
in the cranial vault with subsequent herniation of the
leptomeninges. The origin of cephaloceles located in the
basilar region has been attributed to faulty ossiﬁcation
centers. A cephalocele is usually diagnosed at birth. Dif-
ferentiation from a dermoid, teratoma, vascular malfor-
mation, or hygroma may be difficult. In most cases, the
pathologic factor causing the lesion can be determined
by computerized axial tomography (CT), magnetic reso-
nance imaging (MRI) of the head, or both. Unilateral
exophthalmos can be caused by a cephalocele.
Cephaloceles may be broad—based or pedunculated.
Epithelium may completely cover the sac, or some areas
may be partially transparent. The size of the mass does
not determine whether brain tissue is present. Clinical
classifications by location are occipital, parietal, sincipi—
tal, basal, nasal, and orbital. Occipital cephaloceles are
not difficult to diagnose, compared with the difficulties
encountered in diagnosing nasal ethmoidal, nasal or-
bital, and nasal frontal cephaloceles (Fig. 2). In children
in whom a biopsy of a nasal polyp is contemplated, a
cephalocele needs to be considered (Fig. 3). Skull films
are unreliable in diagnosing basilar and frontal cephalo-
celes in infants. With CT and MRI scans (horizontal,
sagittal, and coronal), the mass can be delineated and the
extent of cerebral tissue involvement determined.
Fourth ventricle involvement from occipital encephalo-
celes can be identiﬁed from MRI prior to surgery (1).
Testing for visual evoked responses (VERs) in children
with occipital cephaloceles is helpful in ascertaining
whether cerebral tissue is present in the sac, but it does
not reveal the functional capacity of the tissue. The ab-
sence of VERs is of no diagnostic importance.

CONGENITAL AND DEVELOPMENTAL CRANIAL ABNORMALITIES / 27
When cerebrospinal ﬂuid (CSF) is leaking or the skin
is extremely transparent, surgery should be done early.
The operation is done to remove the mass, not to irn—
prove the neurologic status. Surgical treatment of small
occipital lesions is not formidable, and mortality is mini-
mal. The prognosis for patients with occipital cephalo—
celes depends on the amount of cerebral tissue displaced
extracranially. Brain tissue in the encephalocele is invari-
ably dysgenetic. Hydrocephalus, which occurs in 50 per-
cent of these patients, and associated brain abnormali-
ties, which are also commonly present, increase the
probability that both motor and mental neurologic defi-
cits will develop.
Anterior malformations (nasal frontal, frontal orbital,
and nasal ethmoidal) are more difficult to treat than oc-
cipital lesions, and multiple surgical procedures are
usually required. Intracranial closure of the dura is un-
portant to prevent CSF leakage. An encephalocele in
FIG. 3. Nasal encephaloceles projecting through the nasal-
frontal bone junction should be differentiated from dermoids
and ectopic gliomas.
FIG. 2. Large oocipital encephalocele.
these areas may involve only the "silent" areas of the
frontal lobe or may involve vital structures of the hypo-
thalamus.
The risk of infection, CSF leakage, and skin erosion is
increased in patients in whom the lesion is not repaired.
Dermal Sinus Tracts
Dermal sinus tracts are tubes of stratified squamous
epithelium, most of which are located in the lumbosacral
area. Giuffroe and Curatolo reported 46 cases of cranial
dermal sinus; in the majority, signs and symptoms devel-
oped before four years of age (2). A nridoccipital location
predominated (85 percent) (Fig. 4). Cheek and Laurent
reported the largest series of patients with congenital na-
sal dermal sinus (3).
Congenital dermal sinus tracts develop in the third to
fifth week of gestation as a result of incomplete separa-
tion of the neuroectoderm from the epithelial ectoderm.
These tracts can extend to any depth into the neural
tissue, depending on the stage at which incomplete dif-
ferentiation occurred. Because closure of the neural tube
begins in the cervical region and extends in both caudad
and cephalad directions, the possibility of incomplete
cleavage is greatest in the caudal direction. The tracts
will extend cephalad when located over the spinal area
and caudad when located above the occipital protuber-
ance. Nasal sinus tracts project posteriorly toward the
crista galli. Because of their embryonic origin, a midline
or near—midline location is characteristic.
Posterior cranial sinus tracts originate above the exter-
nal occipital protuberance, and nasal sinus tracts origi-
nate predominantly at the distal third of the nose (Fig. 5).
Both of these lesions may extend into the scalp, the skull,
the extradural space, or the intradural space. Expansions
can occur at the terminus or along the course of the tract.

28 CHAPTERS
FIG. 4. Posterior dermal sinus tracts commonly pierce the
skin above the torcula and track caudally into the posterior
fossa.
These expansions are considered dennoids, because at
least two germinal cell layers can be seen on histologic
examination.
A dimple, often with protiuding hairs and a port wine
discoloration of the skin, will be present on the skin at
FIG. 5. Nasal dermal sinus tracts pierce the skin at the ante-
rior third of the nose and track under the nasal bones to the
falx cerebri.
the entrance to the sinus tract. The patient may have
recurrent episodes of Staphylococcus aureus meningitis.
Symptoms may occur that suggest the presence of a mass
in the posterior fossa, or a cerebral abscess. leakage of
material from the dermoid may cause aseptic menin-
gitis.
A smooth, rounded midline defect and grooving of the
calvarium in the occipital bone may be seen in radio-
graphs. Nasal sinus tracts with an intracranial extension
are frequently associated with a wide or bifid crista galli
on frontal polytomographic radiographs. A CT or a MRI
scan may show a mass, bony abnormalities, or a cyst
with brain displacement. There is usually no significant
enhancement.
Surgery should be done before adhesions secondary to
meningitis can develop. The treatment consists of total
excision of the sinus tract, including any intracranial ex-
tensions.
Epidermoids and Dermoids
Epidermoids comprise 1 percent of cerebral neo-
plasms, and dermoids not related to a sinus tract com-
prise a lower percentage. Both lesions are believed to be
inclusion cysts of epithelial cells that develop during clo-
sure of the neural tube in the third to fifth week of gesta-
tion. A predilection for a midline location supports this
theory. Entrapment of rest cells during closure of optic
and otic vesicles may explain the developmental lesions
in these areas.
Cruveilhier‘s use of the term "tumour pearles" in
1829 was a classical description of the lesions that later
became known as epidermoids. The cysts are composed
of a stratified squamous epithelial lining and expand in-
ternally by exfoliation of keratin debris. The content of
an epidennoid is more ﬂuid than that of a dermoid. Ex-
tracranial lesions occur in the anterior fontanelle and the
frontal and parietal diploe (Fig. 6). Intracranial lesions
tend to be paramedially located. The cerebellopontine
angle, the parapituitary area, and the ventiicles are the
major locations of epidermoids, in order of descending
frequency.
Dermoid cysts are composed of hair follicles, sweat,
and sebaceous glands, in addition to squamous epithe-
lium, and become enlarged owing to deposition of kera-
tin debiis, hair, and material from the sebaceous cysts.
Thus, the contents of these cysts have a "cheesy" consis-
tency. Common extracranial locations of dermoid cysts
are the anterior temporal area, the supraorbital diploe,
the bridge of the nose, and the occipital region. When it
is located at the nose or occipitally, the cyst may have
eroded through the inner table and expanded extradur—
ally. Intiacianial dennoids usually occur in the fourth
ventricle, the posteiior fossa, the vermis, or the region at
the base of the skull.

CONGENITAL AND DEVELOPMENTAL CRANlAL ABNORMALlTlES / 29
FIG. 6. Common location of an epidermoid cyst is at sutural
junctions.
Palpable epidermoid or dermoid cysts are nontender,
relatively immobile, and firm. Tenderness, if present,
may be a result of trauma or infection. The difference
between dermoid and epidermoid cysts is histological.
Both types may produce the same changes in radio-
FIG. 7. An anterior fontanelle dermoid seen on a coronal CT
scan.
graphs. Lesions in the calvarium can usually be diag-
nosed by routine skull radiographs and are seen as
sharply marginated, lucent defects with sclerotic edges.
Intradiploic enlargement is occasionally present. Ero-
sion of the outer table is connnon, but inner table ero-
sion is rare (Fig. 7). Both intradural epidermoids and
dermoids may become calciﬁed. Angiography will reveal
an avascular mass if the lesion is large enough to displace
vessels. A CT scan is helpful in establishing the diagnosis.
These lesions connnonly appear as low—density masses,
and no enhancement has been reported.
The treatment for extracranial dermoids and epider-
moids is complete excision; for skull lesions the bone
edges must be curetted to achieve a complete cure. Intra-
cranial lesions are more difficult to treat, depending
upon their size and location. Complete resection is the
aim of therapy. Any remaining epithelial cells will con-
tinue to keratinize and desquamate, and the mass will
recur. Spillage of the cystic material at operation can
cause a severe aseptic meningeal reaction, but high doses
of steroids will minimize this risk.
CONGENITAL INTRACRANIAL CYSTS
Developmental Cysts
A wide variety of nonneoplastic intracranial cysts has
been described in the literature, the etiology and patho-
genesis of which are controversial. The classification sys-
tem for these cysts is unjustified, but common usage of
certain terms has prevailed (4).
Arachnoid cysts can occur anywhere in the cranial
vault. The most corrnnon supratentorial site is the syl-
vian area or middle fossa. Other locations are the parasa—
gittal area, the convexity, and the posterior fossa (Fig. 8).
The abnormal development of the perimedullary mesh,
with collections of ﬂuid between the arachnoid leaves,
may cause these cysts to develop, or a dysgenetic portion
of the brain may cause an arachnoid malformation
which then fills with ﬂuid. The treatment of cysts of ei-
ther origin is the same.
The wall of an arachnoid cyst is smooth, with no evi-
dence of inflammation or hemorrhage. No secretory epi-
thelium can be seen on microscopic examination. Brain
tissue adjacent to the cyst may be normal, gliotic, or
dysgenetic. Bony erosion and bulging are corrnnon when
the cyst is located in the temporal fossa. The cysts are
usually filled with clear ﬂuid, but occasionally the ﬂuid
will be xanthochromic and will have a high protein con-
tent. Some cysts freely communicate with the basal cis-
tern, particularly those in the temporal fossa, making
them diverticulae rather than true "cysts."
The location of the cyst determines the manner in
which it is manifest. Supratentorial lesions in infants will
cause megacephaly or signs of increased intracranial

30 / CHAPTERS
pressure. The head will be asymmetrical, and focal nedro—
logic signs may be present. An infratentorial cyst may
produce signs and symptoms similar to those caused by
tumors of the posterior fossa. The clinical course of both
supratentorial and infratentorial cysts is prolonged, un-
less bleeding into the cyst should occur.
The natural history of arachnoid cysts varies. MRI
scans in sagittal and axial planes are helpful in planning
the surgical approach. Cyst—peritoneal shunts, resection
of cyst wall, and opening of the cyst into the ventricle or
the basilar cisterns are the most commonly used surgical
treatments.
FIG. 9. Skull radiograph demonstrates calvarial distortion (an
elevated inion) due to a Dandy—Walker cyst.
FIG. 8. Surgical view of a posterior fossa arach-
noid cyst that was diagnosed in utero.
Ependymal cysts do not develop in the ventricular sys-
tem or the subarachnoid space but presumably originate
from displaced ependymal cells. Their lining resembles
the ciliated cells of the normal ependyma and probably
maintains a secretory capability. The ﬂuid is hyperosmo—
lar and has a high protein content. Ependymal cysts
manifest signs and symptoms resembling those of a
space—occupying lesion. Diagnosis is commonly made
by CT or MRI scanning. Bony erosion is uncommon. A
cure is effected by excising the cyst wall.
A porencephalic cyst is a cavity communicating with
the ventricular system. An antecedent vascular occlu-
sion is the rnost likely origin. It is possible to diagnose
many of these lesions in asymptomatic patients with CT
or MRI scanning. Multiple ventricular punctures in in-
fants with high—pressure hydrocephalus may cause these
"cysts" to develop. Ifthe porencephaly is associated with
hydrocephalus, a shunt will be necessary. Differentiation
between "true" cysts and porencephalic cysts may be
difficult. The underlying pathological changes will deter-
mine the prognosis (Fig. 9).
Colloid Cysts
"Colloid cyst," "paraphyseal cyst," "neuroepithelial
cyst," and "cyst of the foramen of Monro" are the
various terms used to describe this lesion originating at
the median or paramedian embryonic structure from
which the roof of the third ventricle develops (Fig. 10).
Although the surface of the outer wall of the cyst is di-
rected into the third ventricle, no cilia are located on this
anlage gland to the paraphysis. Normally, this third ven-
tricular gland involutes by the fourth month of gestation.

CONGENITAL AND DEVELOPMENTAL CRANlAL ABNORMALTTIES / 31
FIG. 10. A CT scan demonstrating the typical location ot a colloid cyst.
In some cases, the choroid may be the origin of colloid
cysts, and occasionally cilia can be seen microscopically.
Impaction of the cyst in the foramen of Monro can
result in sudden death owing to acute hydrocephalus.
The often—obse1ved intermittency of symptoms is osten-
sibly related to the cyst acting as a "ball valve," periodi-
cally occluding the foramen. There is a high incidence of
narrowing of the aqueduct in patients with colloid cysts.
Symptoms include mental deterioration (fornical dam-
age), intermittent headaches related to the position of the
tumor, and endocrinologic changes secondaiy to hypo-
thalamic damage.
Because of differences in density measurements in
CSF, brain tissue, and the contents of colloid cysts, the
diagnosis can most readily be determined by MRI scan-
ning. Other lesions, especially craniopharyngiomas and
gliomas, may mimic a colloid cyst on CT scanning. Sur-
gical removal of colloid cysts is the best form of treat-
ment. The transcallosal approach with the use of the
operating microscope has lowered the morbidity for this
type of surgery.
CONGENITAL INTRACRANIAL TUMORS
Hamartomas
A hamartoma is a congenital malformation of normal
tissue in an abnormal location. The most common of
these tumors are hypothalamic hamartomas attached be-
tween the tuber cinereum and the mamillary bodies.
These lesions are sometimes located on the ﬂoor of the
third ventricle or may sometimes form a pedunculated
mass in the interpedicular space. Microscopically, the
lesions are composed of fibrous bundles, neurons, and
glial tissue.
Precocious puberty associated with a hamartoma has
been reported (5). It is more common in males, in whom
genitalial signs develop before one year of age. In fe-
males, signs of precocious puberty appear between one
and three years of age. Endocrine studies have shown an
increase in blood levels of testosterone and luteinizing
hor1none—releasing factors. Whether the hamartoma be-
haves as a feedback connection to the hypothalamic
area, an automatous gland, or a mechanical mass that
interferes with normal endocrinological function re-
mains controversial.
CT or MRI scans show these masses to be nonenhanc—
ing, with the same density as brain tissue.
Medical and surgical treatment is necessaiy to reverse
early secondary sexual manifestions and to prevent early
epiphyseal closure. Although histologically benign, ham-
aitomas can cause increased intracranial pressure, and
early surgical intervention may be necessary. Operative
mortality and morbidity should be low when the operat-
ing microscope is used. Hormonal suppression with pro-
gestational agents and cyproterone acetate provides ad-
ditional relief when complete resection is impossible.
The efficacy of radiotherapy is uncertain. Secondary sex-
ual characteristics have been reversed by combined sur-
gical and medical treatments.

32 CHAPTER 3
TeratClVIlVIS
Teratomas are tumors in which the tissue elements are
differentiated from all three germ layers but are alien to
their location. Atypical teratomas, also called germino—
mas. do not originate from teratomatous elements and
are not classified as teratomas. Teratomas are relatively
rare, comprising only 0.5 percent of all primary intracra—
nial neoplasms in the general population. In neonates,
however, 62 percent of tumors are teratomas (6). Most
occur in the midline cerebral plane, with the pineal
gland, suprasellar region, cerebellar vermis, and lateral
ventricles, in decreasing frequency, as the sites of origin.
In neonates, most teratomas are located in the supra-
tentorial space; in patients older than three months,
most are located in the posterior fossa. During the neona-
tal period, teratomas are most common in females. Be-
cause the heads of afflicted children are enlarged, the
most common initial diagnosis is hydrocephalus. Baso—
cranial extension with gross protrusion of the tumor
through a palatobasal deformity can occur. Teratomas
in older children develop before 15 years of age and corn-
monly appear simultaneously with diabetes insipidus.
The clinical course is longer and the prognosis better in
these older children. Carcinomatous changes will deter-
mine longevity.
Calciﬁcations of teratomas are occasionally seen on
routine skull radiographs. A moderate enhancement of
the nrass is shown on CT scan, with evidence of calciﬁca-
tions that may represent teeth. MRI scans greatly aid
in delineating the extent and origin of these masses. Cys-
tic areas and displacement of normal brain can be seen
(Fig. ll).
FIG. 1 1 . A sagittal MRI demonstrating typical location and
enhancing quality of a centrally located teratoma.
Current methods of treatment do not change the poor
prognosis in neonates or children. The prognosis in older
children depends on several factors: whether the terato-
mas can be resected and whether malignant histological
changes have taken place. Shunting procedures to con-
trol hydrocephalus are complicated by the high protein
level in the CSF.
Total excision is usually impossible. Treatment con-
sists of subtotal resection, followed by irradiation, che-
motherapy, or both.
Lipomas
Intracranial lipomas are rare and are usually found at
autopsy or as an incidental radiographic finding. A com-
mon site is the rnidline of the corpus callosum, and par-
tial or complete agenesis of the corpus callosum may be
present.
Other sites are the tuber cinereum, cisterna ambiens,
and cerebellopontine angle. Possible causes are displaced
mesenchymal cells and inclusion of fat anlage cells at the
time of neural tube closure. Most patients with lipomas
are asymptomatic; however, lipomas located in the tec-
turn can cause progressive hydrocephalus. Seizure dis-
orders and hypothalamic symptoms may also be present.
When the lesion is located in the corpus callosum,
skull radiographs may show a characteristic wine glass-
shaped peripheral calciﬁcation surrounding an area of
low density, and CT scans reveal a low—density mass
identical to fat. Surgery is rarely indicated unless the
mass causes hydrocephalus.
MISCELLANEOUS DEVELOPl\/IENTAL
OR CONGENITAL ABNORMALITIES
Phakomatosis
Phakomatoses are neurocutaneous disorders of con-
genital origin that are associated with tumors and inal-
formations of the nervous system. Neurosurgery is fre-
quently considered when one of the following disease
complexes is present: tuberous sclerosis, neurofibroma—
tosis, v0n Hippel—Lindau disease, Sturge—Weber syn-
drome, and melanoma of the leptomeninges.
Sinus Pericranii
Sinus pericranii should be considered in the differen-
tial diagnosis of cranial meningoceles, meningoencepha—
loceles, cephalohematoceles, and subcutaneous cav-
emornas. This lesion is most common in children

CONGENITAL AND DEVELOPMENTAL CRANlAL ABNORMALITIES / 33
FIG. 12. Sinus pericranii have direct venous oonnections to
the sagittal sinus and readily fill when the head is in a depen-
dent position.
younger than two years old. In the majority of repoited
cases, sinus pericranii are congenital in origin, and the
walls of the sinuses are lined with endothelium. Trau-
matic origin has been postulated in some patients, espe-
cially when a fibrous capsule forms similar to a false
aneurysm. Sinus pericranii are collections of nonmuscu—
lar venous blood vessels that communicate directly
through the diploe with a major intracranial sinus,
usually the superior sagittal sinus. Conversely, venous
cavernomas of the scalp communicate with the extra-
cranial venous channels. Few symptoms accompany
sinus pericranii. The mass, which is more common in
the parietal region, is soft and compressible, and it en-
larges when Valsalva maneuvers are performed. Flexing
the neck or maneuvering the head downward will show a
mass containing venous blood. This lesion has a progres-
sive course and will enlarge considerably (Fig. 12).
Changes in bone secondary to continuous venous pulsa-
tions are usually present. Venous angiography is useful
in diagnosing these masses, and surgical removal is rec-
ommended.
REFERENCES
l. Chapman PH, Caviness US. Subtorcular occipital encephaloceles.
Concepts Pediazr Neumsurg l988;8:86—93.
2. Guiffroe R, Curatolo P. Cranial dermal sinuses in childhood and
adolescence. Neurochirurgia l978;2l:72—75.
3. Cheek WR, Laurent JP. Dermal sinus tracts. Concepts PediatrNeu—
rosurg l985:6:63—75.
4. Balsubramaniam C. Laurent J P, Rouah E, et al. Congenital arach-
noid cysts in children. Pediatr Neurosci ( in press).
5. Rammer KS, Perlman K, Humphreys RP, et al. Clinical and surgi-
cal aspects of hypothalamic hamartoma associated with precocious
puberty in a l5—month—old boy. C/1ildsBrain l980;7:l50—l53.
6. Rubenstein LI. Tumors oflhe central nervous system, Fasicle 6.
Washington, DC: Armed Forces Institute of Pathology, 1972.

CHAPTER 4
Princi les ofNeurosurgery,
edite by Robert G. Grossman. Rosenberg © 1991.
Published by Raven Press, Ltd., New York.
Aneurysms and Carotid—Cavernous Fistulas
Robert R. Smith and Jimmy D. Miller
Etiology of Subarachnoid Hemorrhage, 35
Aneurysms, 36
Pathogenesis, 36
Natural History, 37
Signs and Symptoms, 38
Treatment, 39
Mortality and Morbidity
Following Aneurysm Surgery, 46
Saccular intracranial aneurysms are a peculiarity of the
cerebral circulation. Although some aneurysms are
found incidentally during evaluation of an unrelated in-
tracranial disease, they are most often diagnosed after
their rupture. Among the various signs and symptoms,
the sentinel headache is often the earliest warning sign—
or the only sign—of incipient rupture.
The arteries of the cerebrurn are unique in their pro-
pensity to rupture spontaneously and bleed. When the
bleeding occurs primarily within the subarachnoid
space, rather than in brain parenchyma, the condition is
referred to as subarachnoid hemorrhage (SAH). This
term describes a clinical syndrome rather than a clear
pathologic entity.
In the United States, intracranial bleeding produces
half of all stroke deaths. Bleeding from berry aneurysms
of the large vessels at the base of the brain accounts for
almost one—third of these deaths (1,2). Subarachnoid
hemorrhage occurs about equally in men and women,
although men seem to experience slightly less mortality
and morbidity. Unlike intraparenchymal brain hemor-
rhages, there is no definite seasonal prevalence estab-
lished for SAH (3).
The reported incidence of SAH varies widely and de-
pends in part on reporting conditions. In Rhodesia only
3.5 cases per 100,000 population are reported annually,
R. R. Smith and J. D. Miller: Department of Neurosurgery,
University of Mississippi Medical Center, Jackson, Mississippi
39216-4505.
35
Future Trends, 48
Conclusions, 50
Carotid Artery—Cavernous Sinus Fistulas, 50
Signs and Symptoms, 50
Treatment, 51
References, 52
but in Japan 25 deaths per 100,000 population per year
are reported (4,5). In the United States, SAH accounts
for about 16 deaths per 100,000 population. Dietary, he-
reditary, and socioeconomic factors may have some
bearing on the true incidence (2,6).
ETIOLOGY OF SUBARACHNOID
HEMORRHAGE
In children and adolescents, SAH is uncommon.
When it occurs, an arteriovenous malformation (AVM)
is more often found than an intracranial aneurysm (7).
After about 20 years of age, the reverse is true. In 1 to 2
percent of all patients with an aneurysm, an AVM is also
present. The aneurysm is usually found on the major
feeding vessel of the AVM (8).
Subarachnoid hemorrhage also occurs during preg-
nancy; the cause is usually an intracranial aneurysm.
Gestation weeks 13 through 40 seem to be the period of
greatest danger for patients with intracranial aneurysms.
Aneurysms rarely rupture during delivery. Although
many physicians advise caesarian section for delivery,
normal delivery is acceptable in patients with a known
aneurysm, as long as the aneurysm has not caused a re-
cent SAH (9).
In addition to berry aneurysms and AVMs, SAH has
been associated with arteriosclerotic arteries, medial de-
fects, minute aneurysms, ectatic vessels, hypertension,
granulomatous angiitis, and a number of widely recog-

36 / CHAPTER 4
nized structural lesions, such as tumors (10,11). Even
after a thorough clinical and radiographic study, how-
ever, the cause of SAH may be undefined in as many as
20 percent of those who develop the classic features of
the illness. Mortality in this group of patients is ex-
tremely low, averaging less than 3 percent, and rebleed—
ing is unusual. The most common cause of death in this
group is an intracranial aneurysm that fails to fill on
angiogram because of spasm, thrombosis, or its small
size in relation to the parent artery (12). Repeating the
angiogram a week or 10 days later in suspicious cases
identifies the lesion in an additional 25 percent of the
cases studied (12).
Angiography, however, is not without problems as
well as benefits. Although angiographic complications
occur in perhaps 1 percent of good—risk patients, if all
patients are considered, almost 10 percent develop corn-
plications. This includes those who deteriorate from is-
chemic or hemorrhagic deaths immediately following
angiogram. On the other hand, mass lesions are identi-
fied in as many as 12 percent and hydrocephalus may be
found in others. An occasional subdural hematoma
caused by dissection of subarachnoid hemorrhage into
the subdural space may be found on angiography. The
rate of serious angiographic complications is increased
when angiography is delayed until the second post-
hemorrhage week (13). Angiography should be per-
formed soon after bleeding occurs and prior to the time
when ischemic complications and rebleeding are ex-
pected.
Computerized tomography (CT) is of great value in
locating the site and determining the cause of the sub-
arachnoid bleeding. CT also facilitates identification of a
ruptured aneurysm in a patient with multiple aneurysms
and reliably predicts the site of the hemorrhage before
angiography is carried out. Parasylvian hematomas are
typical of middle cerebral aneurysms, and interhemi—
spheric bleeding is typical of aneurysms of the anterior
communicating artery (14).
Magnetic resonance imaging (MRI), using T2-
weighted sequences, has recently been demonstrated to
be comparable to CT scanning in detecting acute SAH
and is superior to CT for the detection of intracerebral
hematomas (15). After four days post—SAH, T,—weighted
magnetic resonance images are much superior to CT
scans for determination of subarachnoid blood (16). The
major drawback of MRI is the limited availability of
compatible monitoring and support systems for use in
the magnetic field.
Rebleeding occurs in a significant number of those
who suffer an SAH. Recurrent hemorrhage may be ex-
pected in almost one—third of cases within eight weeks
(12). In patients with a ruptured aneurysm, the mortality
rate reaches 55 percent in those managed nonopera-
tively; one—third of these deaths are caused by proved
rebleeding (13). When no aneurysm can be identified on
the cerebral vessels, recurrent hemorrhage occurs infre-
quently. B jorkesten and Troupp noted only three deaths
over a 10-year interval in 61 patients with SAH etiology
and a normal angiogram (17).
ANEURYSMS
Pathogenesis
Three hypotheses of the pathogenesis of aneurysms
seem tenable. One group holds that congenital weakness
of the muscular layer allows the inti ma to bulge through,
eventually rupturing the internal elastic membrane by
overdistension. Another group, the postnatalists, be-
lieves that degenerative changes within the vessel wall
damage the internal elastic membrane; postnatalists spec-
ulate that atherosclerosis contributes to the weakness in
the internal elastic membrane. A third group believes
that aneurysms occur as a result of a combination of a
developmental defect and arterial degeneration (2). To
these authors, the median age of occurrence, 55 years,
implies a degenerative process. Microscopic exa1nina—
tion of the arteries of the circle of Willis provides a
broad—spectrum view of the process of aneurysm develop-
ment. Stated in the most basic terms, the cerebral aneu-
rysm seems to be due to defective formation or stress
degeneration of elastic tissue.
Despite lack of acceptance of heredity as a causative
factor, intracranial aneurysms have been reported
among several family members and even in twins
(18,19). These aneurysms may be subclassified accord-
ing to three familial types. Aneurysms accompanying
connective tissue disorders, such as Ehlers—Danlos syn-
drome, have been recognized. As many as 16 percent of
persons with polycystic kidney disease also harbor intra-
cranial aneurysms (20). In a second group of patients,
there seems to be some hereditary tendency to develop
aneurysms. Within this group, patients with hyperten-
sive and hyperlipemic states seem to carry increased risk.
In a third group, some type of familial aggregation oc-
curs in 1 to 2 percent, although the exact relationship
and reasons for the association have never been defined.
Although exclusion of these three hereditary patterns re-
duces the frequency of aneurysms to no more than 1 in
50 of the close relatives of any given patient with a rup-
tured intracranial aneurysm, this figure is still somewhat
greater than is to be expected from the population at
large (21).
Coarctation of the aorta, polycystic kidney disease,
and renal arteiy stenosis have all been associated with
aneurysms in children and young adults. Anomalous de-
Veloprnent of the circle of Willis may also play a part.
Hypoplasia of one or both proximal anterior cerebral
arteries is an apparent progenitor of anterior cerebral
and anterior communicating aneurysms (22). Aneu-

ANEURYSMS AND CAROTlD—CAVERNOUS FISTULAS / 37
rysrns also occur in patients with rnoyarnoya disease,
syphilis, and subacute bacterial endocarditis. Occasion-
ally, intracranial aneurysms develop after head injury
(23,24). Arteriosclerosis of the vessel wall commonly
leads to ectasia and dilatation, but it does not seem to
foster the development of true berry aneurysms (19).
Such ectatic lesions, particularly of the basilar artery,
may present as a mass lesion.
The wall of a cerebral artery is exceedingly thin and
consists primarily of two layers: a muscular layer and an
internal elastic layer. At branches, the muscular coat is
thin and often absent. The internal elastic lamella pro-
vides considerable support and, when intact, can with-
stand pressures exceeding 600 1n1nHg without vessel
wall deformity (25). Both the muscular layer and the
elastic layer fragment at the site of an aneurysm, and
only scattered smooth muscle cells can be demonstrated
in the aneurysm wall. At the junction of the aneurysm,
the muscular coat seems to leave off gradually, and the
elastic layer ends abruptly (26). Aneurysms tend to form
where vessels bifurcate, and the classical model de-
scribed by Forbus demonstrates that the greatest pres-
sure differential occurs at this point (27). Hassler was
able to produce pitting at the apex of the bifurcation,
indicating once again that this was the point of greatest
strain on the vessel wall (11).
Minute aneurysms, less than 2 mm in diameter, are
apparently progenitors of rnaj or berry aneurysms. These
small outpouchings are normally seen in elderly hyper-
tensive patients. They also occur in about one—half of
those who develop large berry aneurysms; the minute
aneurysms themselves may occasionally rupture. Al-
though they are similar to berry aneurysms, their walls
are somewhat thicker, and they are smaller in size. As
their diameter approaches the critical size of 5 to 6 mm
in diameter, they become more susceptible to rupture
(28,19).
Aneurysms also develop in patients with heart valve
vegetation, probably arising secondary to septic emboli
and the accompanying necrosis of the cerebral vessel
wall. Although these mycotic aneurysms account for less
than 2 percent of all aneurysms, they may be a source of
both subaraclmoid and intracerebral hemorrhage (29).
The parietal lobe is most often affected, and hemorrhage
generally occurs about one month or longer following
peripheral septic embolization (30). Follow—up angiogra—
phy, done three to four weeks following hemorrhage,
sometimes shows resolution of the lesion. A trial of anti-
biotic therapy is advised, because the rebleeding rate has
not been established (31). Several fatal rebleedings, how-
ever, have called for recent reevaluation ofthis nonopera-
tive protocol at the University of Mississippi Medical
Center, and surgical clipping of mycotic aneurysms has
been recommended.
True traumatic aneurysms probably occur infre-
quently. They are seen, however, in association with inju-
ries of the anterior cerebral artery near the tentorium
and occasionally on the middle cerebral artery in associa-
tion with bone ﬂaps, fractures, or operative procedure.
Almost any injury may produce false aneurysms which
tend to rupture quite frequently (23).
Natural History
Careful autopsy examination reveals unruptured aneu-
rysms in up to 8 percent of the people who died from
other causes (32). The fact that this large percentage of
unruptured aneurysms is routinely found at postmortem
examination should greatly inﬂuence therapeutic consid-
erations. McCor1nick and Rosenfeld (19) estimated that
these lesions are common and that they may be found in
4 to 6 percent of the population at the time of death; only
one aneurysm out of five ever ruptures. This figure prob-
ably takes into account the minute aneurysms that occur
in the vessels of elderly individuals with hypertension;
those vessels are known to have a low incidence of hem-
orrhage. The size and location of the aneurysm, as well
as the patient's age and the presence ofhypertension, are
factors determining the history of unruptured aneu-
rysms. Aneurysms less than 5 111111 in external diameter
rarely rupture, but often those between 6 and 10 mm
have already bled by the time they are found (28). In
patients less than 50 years of age, rupture has already
taken place in over 80 percent of the cases when the
aneurysm is identified. Those with secondary locula—
tions bleed twice as frequently as smooth—walled lesions.
Even giant aneurysms, commonly believed to be i1n—
mune from rupture, are often a source of SAH (33). Al-
though the chance of a small asymptomatic aneurysm
rupturing has been estimated to be about 0.5 percent per
year, the long—term follow—up of ruptured aneurysms has
shown the rebleeding rate to be much higher. Follow—up
angiography has proven that small asymptomatic aneu-
rysms enlarge overtime.
When patients with a ruptured aneurysm are un-
treated or treated with simple bed rest, recurrent bleed-
ing and vasospasm are the most common causes of1nor—
tality. The greatest incidence of rebleeding occurs
between the fifth and ninth days, with an expected mor-
tality rate of about 7 percent per week during the first six
weeks. The rebleeding rate and mortality depend on the
site of the aneurysm and, apparently, on the pressure in
its parent vessel. Internal carotid aneurysms and middle
cerebral vessel aneurysms seem to bleed earlier than ante-
rior communicating artery aneurysms, which have a
prolonged interval before hemorrhage recurs. After six
to eight weeks, the mortality rate of all ruptured aneu-
rysms begins to fall off, and recurrent bleeding among
the survivors eventually adjusts to around 10 percent
annually. Overall, however, over 50 percent of all pa-
tients with untreated aneurysms die within five years,
usually due to rebleeding (34).

38 / CHAPTER 4
Berry aneurysms may produce intraparenchymal, in-
traventricular, and/or subarachnoid hemorrhages, and
they account for many cases of sudden death in the
United States each year. Middle cerebral artery aneu-
rysms are most commonly responsible for intraparen—
chymal bleeding. Internal carotid—posterior co1n1nunicat—
ing artery aneurysms may have their dome adherent to
the brain tissue and rupture into it. Anterior cerebral
artery aneurysms may rupture into the gyrus rectus.
Signs and Symptoms
The symptoms and signs associated with an intracra—
nial aneurysm are extremely variable, depending pri-
marily on its location, its effect on surrounding struc-
tures, and the volume of blood spilled into the
subarachnoid space. Quite properly, establishing a
prompt diagnosis in a patient with an intracranial aneu-
rysm has been emphasized heavily. Still, it must be recog-
nized that less than 10 percent of all aneurysms cause
symptoms or signs of sufficient magnitude to warrant
diagnostic evaluation prior to the time that bleeding oc-
curs. Again, it appears that a critical size must be reached
before an aneurysm causes any symptoms. At least 75
percent of patients with symptoms have an aneurysm
that measures 10 mm or larger. In other words, the range
between the critical size for rupture of an intracranial
aneurysm (about 6 mm) and the critical size for the pro-
duction of symptoms without rupturing (7 to 10 mm) is
quite narrow.
Headache is a common complaint in patients with an
unruptured aneurysm. They often have no localizing
value, although it is common to find a history of severe
periorbital pain in patients with carotid artery aneu-
rysms. These aneurysms have the greatest propensity to
produce localizing symptoms, while anterior co1n1nuni—
cating and middle cerebral artery aneurysms tend not to
localize. Diplopia and evidence of third cranial nerve
involvement are the symptoms that lead over 90 percent
of the patients with an unruptured internal carotid aneu-
rysm to seek medical attention. Although other cranial
nerves may be involved, aneurysms at the internal ca-
rotid—posterior communicating artery junction most fre-
quently cause this symptom complex. Those located
somewhat higher on the internal carotid artery at its
junction with the anterior choroidal artery may also
cause third cranial nerve involvement, but less fre-
quently. Aneurysms at the junction of the ophthalmic
artery and internal carotid artery are the second most
frequent to produce symptoms prior to rupture. In this
group, headache and orbital pain are probably the most
common complaints, although disturbance of vision ow-
ing to involvement of the optic pathways occurs in about
one—third of patients. Aneurysms of the middle cerebral
artery rarely produce symptoms prior to rupture, al-
though contralateral hemiparetic and sensory distur-
bances and seizures have been described (2).
SAH causes a wide spectrum of clinical signs. Al-
though aneurysms do sometimes rupture during sleep,
certain physical activities seem to promote rupture;
among these, lifting, elimination, and coitus must be
listed (2). By far the most striking feature of SAH is head-
ache. This is of sudden onset, and is due to meningeal
irritation caused by the presence ofblood within the cere-
brospinal ﬂuid (CSF). The patient describes this event as
different from anything previously experienced (35). Vir-
tually every alert patient provides this information in the
anamnesis. It has a sudden onset and regardless of the
site of the aneurysm, radiates into the occiput. The sen-
tinel headache has been described as a premonitory clue,
occurring days to weeks prior to the major catastrophic
hemorrhage. If a careful history is sought, the sentinel
headache occurs in about one—fourth of all who later suf-
fer a major catastrophic hemorrhage (35). Headaches,
nausea, vomiting, and transient loss of consciousness are
described by two—thirds of those who experience SAH.
These symptoms and signs are associated with diifuse
hemorrhage in the subarachnoid space (2). As extralu—
rninal and intraluminal pressures equalize, bleeding
stops.
Patients observed during aneurysm rupture develop
muscular rigidity and tend to show decerebrate postur-
ing. They sweat profusely, their pupils dilate widely, and
they may show clonic movements of the extremities.
Some patients become comatose at onset, and a small
percentage of patients also have grand mal seizure activ-
ity. Patients surviving this major hemorrhage experience
violent nausea and vomiting as they awaken from coma.
Their necks become rigid within the next few hours, and
they complain of neck, back, and leg pain. They are pho-
tophobic and are usually confused and disoriented; local-
izing neurologic findings are often absent. A rare patient
may not complain of headache as the initial symptom.
Some patients note a loud popping sensation, and others
describe a sudden loss of hearing or vision. In some pa-
tients, the peripheral signs and symptoms predominate,
and the back and leg pain may mimic the rupture of a
lumbar intervertebral disc. One—fourth of presenting pa-
tients experience the headache as a relatively minor dis-
comfort. The headache described by these patients may
not reﬂect rupture but rather the sentinel headache that
sometimes prefaces the major intracranial hemorrhage
(35,36).
Certain aneurysms, upon rupture, evoke lateralizing
and localizing neurologic findings. Approximately 50
percent of those located on the internal carotid artery
near the posterior cornrnunicatin g j unction cause ipsilat—
eral pupillary dilatation as the pupillary fibers of the
third nerye are injured. Medial rectus weakness, with
ptosis but with sparing of the pupillary fibers, is ex-
tremely atypical for posterior communicating artery an-

ANEURYSMS AND CAROTlD—CAVERNOUS FISTULAS 39
eurysrns; unless pupillary dilation is noted, the presence
of an aneurysm here can be essentially excluded on clini-
cal grounds. Aneurysms that rupture in the sylvian ﬁs-
sure generally produce intratemporal and sometimes
deep frontal hematomas that cause contralateral hemi-
plegia and occasionally homonymous hemianopsia.
Dominant hemisphere middle cerebral artery aneu-
rysms that rupture may also cause aphasia. Although
vertigo and dizziness have poor localizing value, aneu-
rysms on the posterior cranial circulation are perhaps
more often associated with these symptoms than are an-
terior circulation aneurysms ﬂ3ig. 1). Anterior co1nrnuni—
cating artery aneurysms often produce no localizing find-
ings (Fig. 2). However, in some patients an oral apraxia
develops subsequent to the hemorrhage. The patient
seems alert and responsive but can neither form words
and phrases nor use the mouth and tongue to eat and
speak. In other cases, there may be weakness of one or
both legs secondary to ischemia in the anterior cerebral
artery territory.
Multiple aneurysms are found in about 20 percent of
the patients who experience SAH. Many combinations
are possible, but those asymmetrically placed on the in-
ternal carotid arteries are perhaps the most common vari-
ety (2). When more than one aneurysm is seen, the larg-
est and most proximal lesion accounts for rupture in
over 75 percent of the cases. Secondary loculations, va-
soconstriction, shift, and hemorrhage on the CT scan are
also useful in identifying which aneurysm is the source of
bleeding (37).
FIG. 1. Aneurysms of the posterior circulation occur most
commonly at the basilar apex and usually produce no localiz-
ing signs. Diplopia and vertigo pocur in about 10 percent.
FIG. 2. A large aneurysm of the anterior communicating ar-
tery responsible for recent subarachnoid hemorrhage.
Treatment
Medical Treatment
The best treatment for the patient with a recently rup-
tured aneurysm will confer the best long—term protection
against rebleeding while simultaneously offering the low-
est immediate risk in application. Unfortunately, no sin-
gle therapeutic regimen fits this ideal for all groups of
patients. Many factors bear on this decision, including
age, sex, the clinical condition of the patient, the speciﬁc
aneurysm site, the time interval since hemorrhage, and
the size, and configuration of the aneurysm. The experi-
ence and facilities available also deserve consideration in
selecting the best treatment. The clinical condition or
grade at the time therapy is begun is a fundamental deter-
minant in selecting a treatment protocol (Table 1). Pa-
tients comatose when therapy is begun have the highest
TABLE 1. Definition of neurological condition
Grade Definition
1 Symptom-free
2 Minor symptoms (headache, meningeal
irritation, diplopia)
3 Major neurological deficit but fully responsive
4 Impaired state of alertness but capable of
protective or other adaptive responses to
noxious stimuli
5 Poorly responsive but with stable vital signs
6 No response to address or shaking,
nonadaptive response to noxious stimuli,
and progressive instability of vital signs
From ref. 92, with permission of the American HeartAssoci—
ation, Inc.

40 / CHAPTER 4
mortality rate, and alert patients, the lowest. In patients
randomly allocated to a bed—rest treatment program, the
mortality rate among grade 1 patients is 36 percent and
100 percent among grade 6 patients. The quality of life
for survivors also correlates closely with the clinical
grade (3 8). Unless an intraparenchymal clot is present,
little is gained by an immediate operation in the high-
risk patient; many such patients improve on a conserva-
tive program, thereby allowing a deﬁnitive operation to
be performed later with less risk.
It must also be recognized that some aneurysms in
some patients cannot be clipped. In other patients, be-
cause of their clinical condition, the operative mortality
associated with the procedure negates any long—ter1n
benefits. Perhaps the greatest single factor bearing on
aneurysm mortality is the timing of the operation per-
formed (3 8). Saito reported an 18 percent mortality rate
in patients operated on earlier than the seventh day
posthemorrhage. In those operated on after the eighth
day, however, the mortality rate was only 3.7 percent
(39). Likewise, Graf and Nibbelink noted a 44.5 percent
mortality rate among patients operated on during the
first week after SAH (40). More recent studies have sug-
gested that postoperative morbidity and mortality occur
largely in patients who undergo surgery three to seven
days after hemorrhage. These authors have questioned
the common treatment protocol of delaying surgery for
about two weeks after SAH for patients in grades 1 and 2,
and they have concluded that the risk of rebleeding is
higher than the risk of very early operation in these alert
patients (38,41). Although this point is not settled, there
is common agreement that surgery aggravates the vaso-
constriction and edema (especially pronounced on days
three to seven) associated with hemorrhage. Progressive
decline in neurologic function accounts for 8 to 10 per-
cent of the deaths that follow SAH, and these usually
occur within two weeks of initial hemorrhage (13). It
appears that an aggressively applied conservative treat-
ment program reduces the early risks of rebleeding to less
than 10 percent over a 14-day interval. By this time
edema has subsided, vasospasrn (whatever its mecha-
nism) is resolving or has stabilized, and most ofthe blood
within the subarachnoid space has cleared. Early opera-
tion is difficult to justify in patients in grades 3 through
6. Many patients in these grades improve with conserva-
tive treatment, and operative deaths decrease sharply as
the level of consciousness rises (38). As indicated, the
question of early operation versus risk of rebleeding has
not been settled in grades 1 and 2. One point stands out
clearly at the present time: unless the surgeon can oper-
ate on the good—risk patient within the first 48 hours,
surgery should be delayed until the second posthemor—
rhage week. Angiography should be performed on the
day prior to surgery to assess the status of the intracranial
vessels.
General Measures
Simple bed rest has long been recognized as beneficial
in preventing rebleeding. Even during the third week,
however, rebleeding still occurs in about 10 percent of
patients. The bed—rest program must not, therefore, be
terminated before the fourth week. Beyond this time,
rebleedings diminish to about 1 percent per month, and
at this time the patient is allowed to sit up in bed and to
become progressively ambulatory in the ensuing weeks
(13). Additional supportive measures include the follow-
ing:
1. Close observation, preferably in aprivate room in an
intensive care unit.
2. Elevation of the head of the bed to 30 degrees.
3. Stool softeners.
4. Bedside cornrnodes.
5. Airway maintenance.
6. Oxygen requirements.
7. Seizure prophylaxis with phenytoin.
8. Adequate ﬂuids (1,500 to 2,000 ml per 24 hours by
mouth, nasogastic tube, or intravenously).
9. At least 1,000 calories of nutrition per day.
10. Diazapam, phenobarbital, or chloral hydrate for se-
dation as needed for restlessness.
11. Catheter in the incontinent patient; otherwise nor-
mal voiding is permitted.
12. Analgesics such as aspirin, codeine, or meperidine as
necessary for pain.
13. Control of vomitin g, nausea, and singultus with phe-
nothiazines.
14. Antiembolic stockings to prevent deep vein throm-
bosis in the nonambulatory patient.
The use of steroids and other antiedema drugs is con-
troversial but common. The greatest frequency of re-
bleeding using this protocol occurs between the fifth and
ninth days, and the great majority of deaths from re-
bleeding occurs within 30 days ofthe initial hemorrhage.
Patients in poor condition with more than one co1npli—
cation, such as myocardial infarction and hypertension,
carry the highest risk (13). Because of age, vascular dis-
ease, dehydration, and immobility, the typical patient
with SAH runs a great risk for deep vein thrombosis and
pulmonary embolism. Needless to say, anticoagulants
are contraindicated.
Hypolensive Therapy
Two therapeutic methods utilize hypotension in vary-
ing degrees to decrease the likelihood of rebleeding: (1)
profoundly lowering blood pressure to the point of cere-
bral ischemia (42), and (2) reducing the systolic thrust on
the aneurysm wall through a variety of antihypertensive
medications.

ANEURYSMS AND CAROTID—CAVERNOUS FISTULAS / 41
The profound hypotension regimen calls for both
chemical and mechanical means to reduce the pressure.
A tilt table is usually employed, and reserpine is adn1inis—
tered intramuscularly and hydrochlorothiazide orally.
The desired pressure changes are achieved when perfu-
sion of the brain and other vital organs is just adequate
(43). An attendant is necessary at all times because there
are many possible complications, including decubitus
ulcers, septicemia, hypostatic bleeding, and urinary tract
infections (43). Profound hypotension has never gained
a large number of proponents, no doubt because of its
complexity. There has also been general criticism of the
technique because it may precipitate cerebral infarction
in patients already susceptible because of vasoconstric-
tion.
The second method, drug—induced hypotension, alone
or in combination with other types of therapy, has
gained support. Diuretics, methyldopa, reserpine, and
hydralazine, used either alone or in combination, have
been employed to reduce overall pressure (34). Mechani-
cal means are not used, although the patient is n1ain—
tained on a routine bed—rest protocol, as outlined in an
earlier section. However, moderate drug—induced hypo-
tension as the only treatment is less effective than antifi—
brinolytic treatment. Induced hypotension must be used
with care, because it can produce ischemic cornplica—
tions and can aggravate cerebral ischemia caused by the
vasoconstriction often seen in patients with SAH (34).
Antifibrinolytic Therapy
Mullan and coworkers were the first to realize that the
thrombus within the wall of the aneurysm protected
against premature rebleeding and that its effect could be
prolonged with the antifibrinolytic agent epsilon—arnino—
caproic acid (EACA, Amicar) (44). This agent and those
with similar action, such as tranexamic acid, inhibit the
conversion of inactive plasminogen into the active ﬁbri-
nolytic enzyme plasnrin. EACA crosses the blood—CSF
barrier very poorly and probably has little effect on the
subarachnoid clot (6). The same may not be true for
tranexamic acid. EACA may be administered intrave-
nously or orally, but in the first few days after SAH,
vigorous intravenous therapy is most effective. To
achieve optimum blood levels, 36 to 48 g per 24 hours is
usually required. If EACA is to be administered orally, it
must be given every two hours, and it is wise to monitor
blood frbrinolytic activity using the fibrin plate method,
clot lyses time analysis, or biochemical assay. Some pa-
tients require lower dosage to promote the clinical effect
(6). However, antifibrinolytic therapy appears to be rela-
tively safe and seems to be effective in preventing pren1a—
ture rebleeding, although it may be associated with
higher rates of ischemic deﬁcits and hydrocephalus (45).
Most of those in whom recurrent bleeding occurs are
affected before antiﬁbrinolysis has been achieved. There-
fore, prompt administration is necessary (6).
Deep vein thrombosis occurs in a high percentage of
patients treated with bed rest, and it is not surprising that
this condition and associated pulmonary embolism have
been reported in patients receiving antifibrinolytic ther-
apy (46). A peculiar arteritis follows antifibrinolytic ther-
apy. It also seems plausible that an increased incidence
of hydrocephalus can be expected when tranexamic acid
is used. This agent crosses the blood—brain barrier in
higher proportions than EACA and may inhibit lysis of
the subarachnoid clot. Ideally, antifibrinolytic therapy
should be combined with operative clipping of the aneu-
rysm to prevent late hemorrhage. The agent should be
terminated immediately after operation or after 14 days
of therapy on a gradual withdrawal regimen. Rebound
rebleeding has been described (6).
Antifibrinolytic therapy has been combined with hy-
potensive therapy. In one controlled study, the con1bina—
tion did not seem to be as effective as antiﬁbrinolytic
therapy alone (34). The clinical trial, however, contained
more seriously ill patients in the group that received the
combined treatment than in the group that received an-
tifibrinolytic therapy alone, so the question of effective-
ness ofthe combined therapies remains open. At the pres-
ent time, the use of antifibrinolytic therapy to prevent
rebleeding is controversial because of the increased inci-
dence of the ischemic deficits that are associated with
its use.
Intensive Care and Monitoring
Evidence of increased intracranial pressure (ICP) is a
nearly universal finding in patients with SAH. Flattening
of gyri, herniation, and areas of focal edema are found
routinely in the brains of patients who died following
SAH. Focal edema may further reduce cerebral perfu-
sion and affect late morbidity. The measurement and
monitoring of ICP has recently become available in
many clinics, and reports of successful ICP reduction
have appeared. Nornes described two types of pressure
peaks following SAH (47). Type 1 peaks reach 900
mmH2O, persist for 30 nrinutes or longer, then fall to
normal levels. They are compatible with survival. Type 2
peaks occur suddenly, may reach 2,000 mmH2O, and
are unresponsive to hyperventilation or dehydrating
agents. They may represent recurrent hemorrhage and
are usually accompanied by deterioration in clinical
grade. Ninety percent of patients showing type 2 curves
die. Elevated ICP following SAH is often difficult to re-
duce with hyperventilation. Mannitol in doses of 20 to
100 grams, spinal drainage, and ventricular drainage will
generally cause some reduction in pressure. Monitoring

42/
ICP may also serve as a guide for the timing of surgery.
Monitoring and controlling pressure may allow i1nprove—
ment in the clinical status of the patient categorized in
grades 3 through 6, thus making the patient a more suit-
able candidate for aneurysmal repair. ICP values lower
than 200 mmH2O are generally associated with a favor-
able operative result, but mortality is high in patients
with increased ICP (48).
Operative Management
Carotid Artery Ligation
Since the late nineteenth century, carotid artery liga-
tion has been employed for intracranial aneurysms (49).
The earliest series of patients showed that carotid artery
ligation was both safer and more effective in patients
with infraclinoid aneurysms than in patients with aneu-
rysms located more distally (50). When adjustable
clamps were introduced, many clinics performed carotid
occlusions in patients with carotid artery aneurysms. Al-
though surgeons have asserted that internal carotid ar-
tery ligation provides the best protection against rebleed—
ing, common carotid ligation, which preserves some
ﬂow in the internal segment, has been more widely ac-
cepted (Fig. 3). Internal carotid artery ligation provides
better protection against rebleeding but carries the inher-
ent risk of more immediate and serious ischemic co1npli—
cations (8).
The primary rationale for carotid artery ligation is that
Tt reduces the intravascular pressure above the clamp
and within the aneurysm. It decreases forces on the aneu-
rysm wall, and it causes ﬂow reduction as well. This is
lntemal Carotid Artery
Disengages
Common Carotid
Artery
FIG. 3. In order to preserve circulation in the internal carotid
artery, the Crutchfield clamp is applied to the common carotid
artery 1 cm beneath the bifurcation. The usually occurring
flow pattern is illustrated. The common carotid artery may
thrombose after the clamp has been secured. (From ref. 91,
with permission.)
reflected by a fall in retinal arteiy pressure, and after
carotid ligation, an average reduction of 40 percent in
retinal artery pressure has been noted, as compared with
the pressure of the control eye. The reduction in pressure
continues for many months after ligation and, in some
cases, intraaneurysmal thrombosis occurs after proximal
vessel ligation (51).
In terms of efficacy, it has been difficult to compare
carotid artery ligation with other modes of therapy. It is
widely believed that, in the short run, carotid artery liga-
tion proves superior to a direct intracranial approach,
but that it is less effective in preventing long—term late
rebleeding (52). Odom and Tindall have reported only a
3.7 percent rebleeding rate (53), but other researchers
have recognized a 10 percent rebleeding rate. When
anomalies of the circle of Willis isolate an anterior corn-
municating aneurysm to the ﬂow distribution of one ca-
rotid artery, carotid artery ligation seems to reduce the
incidence of fatal rebleeding. For middle cerebral aneu-
rysms, intracranial clipping is probably the preferred
treatment. However, in patients of advanced age whose
neurologic or medical status is poor, carotid ligation may
be the only alternative. There is little doubt that carotid
ligation, in the presence of vasospasm, exacerbates is-
chemic complications. Ligation should be deferred until
the patient's condition improves and stabilizes. The
clamp may be applied, but total occlusion should be de-
ferred until the vasoconstriction abates.
Technique. Local anesthesia is usually preferred in ori-
ented and cooperative patients; otherwise, general anes-
thesia is in order. After making an incision over the ante-
rior border of the sternocleidomastoid muscle, the
carotid artery is exposed at the bifurcation. A Crutch—
field, Selverstone, or other clamp is placed about 2 cm
beneath the bifurcation and the screwdriver portion at-
tached (Fig. 3). At the time of the operation, it is wise to
occlude the artery totally with the clamp and then back
off four or five turns (54). Some surgeons have empha-
sized the prognostic value of pressure measurement dis-
tal to the clamp. If the pressure reduction is less than 50
percent with the clamp closed, total closure can usually
be carried out in three or four days. When it exceeds 50
percent five to seven days may be needed (54). Others
believe that these tests needlessly complicate the opera-
tion and have no prognostic signiﬁcance. Postopera-
tively, bed rest is continued until the clamp has been
totally closed and the screwdriver portion has been re-
moved.
The incidence of recurrent hemorrhage after carotid
artery ligation is about 10 percent in patients followed up
to 15 years (8). Complications other than rebleeding,
such as ischemia and distal embolization, occur in less
than 5 percent of patients. These complications may
arise at any time following surgery: within the periopera—
tive period, within the first 24 hours, or many years later
(8,54). If other vessels become involved with atheroma,

ANEURYSMS AND CAROTlD—CAVERNOUS FISTULAS / 43
late ischemic complications may arise. In addition, sister
aneurysms seem to develop on the circulation opposite
to that of the carotid ligation. Therefore, ligation of the
carotid artery should be reserved for those patients in
whom alternative treatments are not effective. Further-
more, it should be applied only to those patients with
aneurysms low on the internal carotid artery or in the
cavernous sinus and to older individuals who cany in-
creased risk factors for an intracranial operation.
Intracranial Approach
Careful preoperative conditioning of the patient and
planning of the operation itself are vital for a successful
outcome. If possible, the patient should be in stable phys-
ical and neurologic condition. Little advantage seems to
accrue from operating on patients in grades 4 through 6.
Because progressive vasoconstriction precludes use of in-
traoperative hypotension and often heralds progressive
deterioration in neurologic status after the operation, a
recent angiogram should indicate stable hemodynamics.
The presence of angiographic vasoconstriction does not
necessarily rule out an operative approach, because re-
bleeding may be the alternative. However, operative tech-
niques and adjuncts must be used to compensate for the
decreased perfusion expected in the presence of severe
vasoconstriction. Optimally, a CT scan should show dis-
solution of the subaraclmoid blood, and there should be
no evidence of autonomic dysfunction. The clinical
grade and condition of the patient, however, are proba-
bly the rnost reliable indicators of postoperative out-
come.
General endotracheal anesthesia is required. From the
surgeon's viewpoint, it is ideal to have the patient
awaken from anesthesia relatively soon after the opera-
tive procedure to allow monitoring of vital neurologic
signs. The anesthesiologist should be comfortable with
the use of hyperventilation to provide hypotension at the
appropriate times. Spinal drainage is desirable in most
instances to lessen the amount of retraction necessary for
exposure. Because dehydrating agents greatly increase
urine output, a urinary bladder catheter is required to
monitor output and to prevent complications from a dis-
tended bladder. Central venous and arterial pressures
must be monitored continuously, and if there has been
evidence of congestive heart failure, pulmonary artery
wedge pressure and cardiac output should be assessed
during the operation as well. Frequent assessment of
blood pH and CO2 and 02 levels is also essential.
The patient is positioned on the operating table in a
comfortable position, which both allows for good venous
return and gives the anesthesiologist access to the spinal
drain, endotracheal tube, and arterial lines. The position
of the head may need to be changed during the operative
procedure to achieve maximum intracranial exposure
after the craniotomy: the head should be positioned so
that extension can provide exposure of the vessels along
the base of the cerebrurn. Current rnicrosurgical tech-
niques make excessive brain retraction unnecessary.
However, the operative procedure and flap must be
planned carefully so that covering muscle and bone ﬂaps
do not interfere with direct visualization of the aneurysm
and its parent vessels.
Technique. A basic frontotemporal approach (also
called the pterional approach) as advocated by Yasargil
(55) provides excellent exposure for the clipping of aneu-
rysrns of the anterior cerebral circulation and of the basi-
lar apex. Some modifications of the incision can be used,
depending on the location of the aneurysm. The incision
is directed more superiorly and anteriorly for anterior
communicating aneurysms in order to expose the ﬂoor
of the frontal fossa (Fig. 4). For aneurysms located on the
internal carotid artery and proximal middle cerebral ar-
tery, the approach is directed along the lesser wing of the
sphenoid to the carotid artery (Figs. 5 and 6). We use an
orbitocranial approach for complex and large aneurysms
of the anterior circulation (Fig. 6). The incision for aneu-
rysms of the apex of the basilar artery is placed slightly
more posteriorly to expose the ﬂoor of the middle fossa
beneath the temporal lobe. Aneurysms of th$ basilar
apex may be approached similarly to those of the inter-
FIG. 4. Multiple anterior circulation aneurysms arising from
the internal carotid artery (ICA) at the ophthalmic branch and
from the anterior communicating artery (AcoA). The anterior
clinoid process must be removed to expose cranial nerve
(CN) II and the proximal internal carotid artery. The important
posterior communicating (PcoA), anterior choroidal artery
(AcHoA) and Heubner's recurrent branch (Heubner A) are
shown here.

44 / CHAPTER 4
nal carotid artery in many cases. A very large aneurysm
can obscure the view of the mesencephalon and the per-
forating branches of the posterior cerebral arteries. The
subtemporal exposure allows the aneurysm to be re-
tracted forward and the vessels viewed from the lateral
position.
The bone resection should be co1n1nensurate with the
scalp ﬂap. It is necessary to rongeur away the anterior
portion of the temporal squama and to remove the lat-
eral aspect of the greater sphenoidal wing with a high-
speed drill to expose the anterior surface of the temporal
FIG. 5. Aneurysm of the internal carotid artery (ICA) at
the posterior communicating artery (PcoA) branch.
These aneurysms usually point posteriorly in line with the
anterior choroidal artery (AcHoA). A pterional craniotomy
provides exposure to lesions of the anterior circulation or
to the basilar artery apex.
lobe and the sylvian area. The bone ﬂap can be removed
from the muscle to reduce the total 1nass that 1nust be
retracted inferiorly. Care 1nust be taken to make a care-
fully planned osteoplastic ﬂap and to resuture the muscle
later during the operation, thereby reducing the sunken
appearance ofthe temporal area that may occur with the
pterional approach.
The dura mater is opened just sufficiently to expose
the inferior aspect of the frontal lobe and the temporal
tip (Fig. 6). Microsurgical opening of the araclmoidal
fibers of the sylvian fissure is performed and the middle
|nf.tr.
FIG. 6. Sylvian-splitting incision for aneurysm of the mid-
dle cerebral artery. After incising the arachnoid covering
the fissures, the sylvian veins are retracted exposing the
main trunk (M,) of the middle cerebral artery. Distal dis-
section allows visualization of the lateral striate (L. str.)
and the anterior temporal branch (Ant. tr). Aneurysms
usually arise at M2 at the inferior temporal (Inf. tr.) and
superior temporal (Sup. tr.) junction.

ANEURYSMS AND CAROTlD—CAVERNOUS FISTULAS 45
cerebral Vein and anterior temporallobe are gently _re-
tracted temporally to expose the trifnrcation ofthe 1n1d-
dle cerebral aitery (Fig. 6), the location ofthe great 1najor—
ity of the middle cerebral artery aneurysms. The
exposure of aneurysms of the internal carotid artery re-
quires additional retraction of the anterior temporal
lobe, and therefore the bridging connections of the 1nid—
dle cerebral vein with sphenoparietal sinus 1nust be iso-
lated, coagulated, and divided. In approaching aneu-
rysms of the trunk of the basilar artery, a subteinporal
exposure is usually preferred. The free margin of the ten-
torium can be retracted laterally with a suture to visual-
ize larger aneurysms. An incision can be made along the
posterior surface of the free margin to allow additional
lateral retraction.
For aneurysms of the vertebral artery, a craniocervical
incision provides optimal inicrosurgical exposure (Fig.
7). The upper arm ofthis incision is cairied to the calvar—
iuin, and portions of the occipitalis and rectus muscles
are divided across their fibers to reach the inidline cervi-
cal position. The paraspinal muscles are then unilater-
ally retracted to expose the lamina of Cl and C2. The
advantage of this approach is that it avoids a large scalp
and muscle ﬂap, providing a more shallow wound on the
surgeon's side. Exposure of the intracranial vertebral ar-
tery to the point of its submersion beneath the medulla
oblongata can be achieved by removing a portion of the
laminae of Cl and C2 and by a small suboccipital crani-
ectomy. The dura mater is opened in a Y fashion and
sewn to the adjacent muscles to expose the contents of
the posterior fossa.
Craniectomy
Laminectomy-
administered over a 30- to 40-minute interval as the
bone ﬂap is being developed. The spinal drain is also
opened and allowed to drip slowly. Drainage of 40 to 50
cc of CSF is adequate; excessive removal of ﬂuid should
be avoided. Hypotension may be used to protect the an-
eurysm during dissection either by using a nipride drip,
nitroglycerine, or by increasing the levels of the anes-
thetic agent employed, usually ﬂuothane (Halothane).
Temporary clips are also helpful and restrict the areas of
reduced brain perfusion to the territory of the vessels
occluded. In approaching aneurysms of the larger intra— )
cranial arteries, such as the carotid or basilar, reduction
of the arterial pressure may be desirable. Normally, renal
output remains adequate even when mean arterial pres-
sures of 45 1n1nHg are maintained for an hour or more.
It is prudent, particularly in arteriosclerotic patients and
those with previous renal disease, to monitor urinary
output continuously if systemic hypotension is to be
used.
Hypothermia is now rarely einployedexceptin special
situations in which prolonged interruption of ﬂow in the
major cerebral vessels is anticipated. Most surgeons have
concluded that the moderate protective effect against cir-
culatory airest that can be obtained by hypothermia at
29 to 31 degrees centigrade is outweighedby the co1npli—
cations and inconvenience associated with its use.
Intmopemtive Complications. Rupture of the aneu-
rysm may occur uncommonly during retraction of the
brain or more often during dissection of the neck of the
aneurysm or as the clip is applied. Under these circu1n—
PICA
FIG. 7. Posterior inferior cerebellar artery (PICA) aneurysms arise from the vertebral artery (V.a.) anterior
to cranial nerves (CN) IX, X, and XI at thejunction of V.a. and PICA.

CHAPTER 4
stances, the bleeding point on the dome must be cap-
tured with suction while the aneurysm neck is exposed
for the application of a clip. Other complications that
threaten the safety of the procedure are brain swelling
and inadequate exposure. These may occur when the
patient is operated on too early or when inadequate at-
tention is given to the positioning of the patient on the
operating table. Venous obstruction by drapes or straps,
ﬂuid overload, or an elevated Pcoz secondary to pul1no—
nary complications should also be considered and
corrected if present. E
Mortality and Morbidity Following Aneurysm Surgery
The major factors affecting outcome after surgery are
the preoperative condition of the patient, the location of
the aneurysm, the patient's age, and the presence of va-
soconstriction. The preoperative condition of the patient
can generally be improved with an interval of nonopera-
tive treatment, accepting a risk of about 10 percent for
rebleeding during that interval. Severe hypertension
should also be treated. In patients in good neurologic
condition and without vasospasm, the risks of rebleeding
should be less than 10 percent (5 6). Over 80 percent of
surviving patients should be physically independent, and
the majority should be able to return to their previous
job or to an equivalent job. Postoperative vasospasm is
one significant factor in postoperative disability, and
morbidity increases with age (57).
Cerebral Vasospasm and Constrictive Angiopathy
A complicated series of clinical and radiographic
events following aneurysmal SAH is often referred to as
vasospasm. Lack of understanding of the pathogenesis
and the etiologic mechanisms underlying this response
has rendered the development of an effective therapeutic
plan difficult. There is no entirely suitable animal
model. Although vessel constriction can be produced in
animals by puncture of the major intracranial arteries
and/or by the subarachnoid application of blood OFA?"
soconstrictor drugs, it is short—lived, has no recurrent
phase, and rarely produces a deficit that simulates the
disorder that occurs in humans.
In humans, the pathology is not clear. Focal infarction
has been demonstrated, but it does not invariably coin-
cide with the radiographic picture (5 8). The onset of the
clinical phenomenon of vasospasm rarely occurs within
two to three days of the initial SAH; it usually appears
toward the end of the first week and lasts for a week or
longer. It may also be biphasic, occurring a few days after
hemorrhage and again a week or so later (59). It occurs in
80 percent of patients in stupor, but in only 10 to 15
percent of those who are alert and nearly normalpostop—
eratively. A number of theories have been offered to ex-
plain the complex set of clinical and radiographic find-
ings. Catecholamine depletion in the wall of the cerebral
vessel has led to the hypothesis that denervation hyper-
sensitivity, much like that proposed by Cannon and Ro-
senblith (60), is responsible. Vasoactive substances have
also been isolated from clots that surround the spastic
vessel. Serotonin, prostaglandins, histamines, and other
agents, including products of fresh and aged blood, have
been shown to provoke constriction of the cerebral ar-
tery (6l—63). No agent, however, has been definitely
identified as a primary offender.
A consistent therapeutic plan has not evolved. Agents
that increase levels of cyclic adenosine monophosphate
have shown promise but are somewhat inconsistent in
producing vascular dilatation (64). Recently, the cal-
cium channel blocking agent nimodipine, was tested for
the prevention of vasospasm. No consistent effect on
blood vessel constriction was observed but patients
seemed to benefit in overall outcome. There were, how-
ever, rnore deaths in the treated group than in the pla-
cebo control group (65). Thus, the use of calcium chan-
nel blockade remains highly controversial and must be
tested further. Perhaps the cells responsible for vasocon—
striction will respond to other channel blockers. Induced
hypertension and/or hyperyolemia have been used effec-
tively for reducing ischemic deficits due to vasospasm
(66). The therapy is complex and requires monitoring of
cardiorespiratory function. Undipped aneurysms may
rupture with this treatment protocol, but it may have a
place in the management of mild postoperative vaso-
spasrns. Hemodilution, in certain instances, may also in-
crease perfusion (67).
It is important to emphasize that the term "vaso—
spas1n" should not be used to refer to angiographic con-
striction because angio graphically observed vasospasm
may be related to certain morphologic changes in cere-
bral vessels that have been termed the "constrictive an-
giopathy" of SAH.
The morphologic changes that appear in the cerebral
arteries of persons who died following SAH have been
known for many years. The onset of these changes was
believed to occur late in the course of the disorder, and
the morphologic changes seemed insufficient to explain
the radiographic and clinical findings associated with va-
sospasm. More recently, these changes have been seen as
early as the third posthemorrhage day and consist of pro-
liferation of cells in the intimal layer, and necrosis and
fibrosis in the muscular layer associated with loss of elas-
ticity of the vessel wall (68) (Fig. 8). These structural
changes lead to loss of compliance and expansion at nor-
mal intralurninal pressures. Thus, when viewed both op-
eratively and angiographically, the vessels appear con-
stricted. Clinically, constrictive angiopathy of SAH is
characterized by progressive loss of neurologic function,
lethargy, increasing nuchal rigidity, and a low—grade
fever.

ANEURYSMS AND CAROTlD—CAVERNOUS FISTULAS 47
Associated with this condition, or occurring indepen-
dently, is evidence of hypothalamic dysfunction. Deple-
tion of catecholamines from peripheral sympathetic
nerve endings, anhydrosis, and reduced serum levels of
the catecholamines as well as their enzyme precursor,
dopamine beta—hydroxylase, characterize the condition
(69). There is generalized hypersensitivity to epinephrine
and norepinephrine in many organs, including the skin
and iris muscle. The instillation of 1 percent epinephrine
into the conjunctival sac produces wide pupillary dilata-
tion, indicating denervation hypersensitivity. The ad-
ministration of antihypertensive agents may produce
false positive reactions (69). The significance ofthe hypo-
thalamic dysfunction can be best ascribed to generalized
loss of stress tolerance. The patient withstands the opera-
tive procedure poorly and deteriorates postoperatively
because of both neurologic and systemic complications.
The operation should be deferred until the instillation of
epinephrine into the conjunctival sac fails to produce a
widely dilated pupil. Further evaluation can be obtained
by placing one drop of 10 percent cocaine solution over
the pupil. Cocaine prevents the absorption of norepi-
nephrine into the I161'V€ endings and thereby makes it
more available for receptor uptake, causing pupillary di-
latation in the normal patient. In the case of sympathetic
nerve transmitter depletion or hypothalamic failure,
however, norepinephrine release is diminished, and
therefore the pupil remains small. This paradoxical reac-
tion to cocaine and norepinephrine helps to establish a
diagnosis, although the measurement of catecholamines
and dopamine beta—hydroxylase would be substan-
tive (69).
At present, little is known about the etiology of the
constrictive angiopathy of SAH, much less its medical
FIG. 8. The angiopathy of subarach—
noid hemorrhage. These vessels
show proliferation of cells in the subin—
timal layers and necrosis in the muscu-
laris. These changes often accom-
pany angiographic vasospasm.
and surgical management. Neither previous operative
procedures nor the age and sex of the patient seem to
have any bearing on the disorder. SAH seems resistant to
steroids. Damaged vessels lie adjacent to vessels that are
totally spared in the sa1ne pool of blood within the sub-
arachnoid space. One possible factor may be bleeding
into the wall of the vessels; however, this finding is not
uniform. It is also possible that some intense vascular
constriction damages the cerebral vessel and results in
the later development of angiopathy. Only fragmentary
evidence, however, suggests any correlation between this
theoretically intense vasospasm and constrictive angio-
pathy. More than likely, the constricted appearance on
radiographs is due to the morphologic and physiologic
changes that take place in the cerebral artery, particu-
larly when angiopathy is seen late in the second week
following SAH (70). Occasionally, apatient with symp-
tomatic angiopathy will respond to volume loading with
intravenous ﬂuids.
Transcranial Doppler (TCD) sonography is useful few-
evaluating the patient with delayed ischemic deﬁcits. Ve-
locity in the middle cerebral artery may increase four or
five times as vasospasm progresses (normal 40 to 80 c1n/
sec). Stabilization or reduction of velocity is a good indi-
cation ofiinproved circulation but may also occur with
proximal progression of the spasm to the carotid seg-
ment. We employ the TCD, alone or with angiography.
in patients with a stable clinical course to aid in the ti1n—
ing of operative therapy.
Other Complications of S ubarachmoid Hemorrhage
Obstiuctive hydrocephalus has been a recognized
complication of SAH since 1928 (71). When headache,

48 / CHAPTER 4
mental confusion, and a worsening state of conscious-
ness develop following SAH, this complication must be
considered. Pyramidal tract signs and convulsions occa-
sionally appear, usually within three or four weeks of the
initial hemorrhage but sometimes delayed six months or
longer. Obstructive hydrocephalus develops far more
frequently after rupture of an aneurysm of the anterior
communicating, posterior communicating, or basilar ar-
tery than after rupture of other arteries. Multiple epi-
sodes of hemorrhage seem to be more important than
the total amount of blood released into the subarachnoid
space, but the mechanisms for the development of hydro-
cephalus following SAH are as yet unclear (71). Perhaps,
as suggested by Bradford and Sharkey (59), the red blood
cells block the avenues of escape of CSF. Fibrous lepto-
rneningeal thickening has also been noted. The diagnosis
is easily established by CT, which confirms ventricular
enlargement. Drainage alone, repeated lumbar punc-
tures, or shunting procedures may improve the patient's
condition dramatically.
The electrocardiographic and cardiovascular changes
associated with SAH have been well described, although
the mechanisms by which they are produced are quite
controversial. Sometimes these changes are acco1npa—
nied by massive sympathetic discharge and cardiac fail-
ure. Reduction in intracranial pressure seems to be the
mainstay in treatment, although permanent heart rnus—
cle necrosis is probably a residuum of the most severe
examples.
Terson's syndrome (intravitreal, especially retinal,
preretinal, and subhyloid hemorrhage) occurs corn-
monly with ruptured intracranial aneurysms. Almost 50
percent of patients with a recent SAH have intraocular
hemorrhage, the most common of which is the subhy-
loid type. Contrary to popular belief, few patients experi-
ence complete recovery of vision following massive in-
travitreal hemorrhage; the scar persists long after
resolution of the liquid clot. Because there is no definite
communication between the sub arachnoid space and vit-
reous cavity of the eye, the hemorrhage must result from
rupture of veins secondary to transmitted venous pres-
sure (72).
The syndrome of inappropriate antidiuretic hormone
(SIADH) following SAH is well known and is principally
associated with aneurysms of the anterior cornrnunicat—
ing artery. In the presence of normal adrenal and hepatic
function, the criteria for diagnosis includes hyponatre—
rnia, normal hydration, serum hyposrnolarity, and urine
hyperosmolarity. Often confused with SIADH is a con-
dition associated with increased ﬂuid volurne secondary
to expansion of the extracellular space. This apparently
results from decreased renal blood ﬂow secondary to the
massive sympathetic discharge that occurs. SIADH asso-
ciated with SAH should be managed primarily by water
deprivation. As the serum sodium falls, the patient be-
comes progressively lethargic and seizures may ensue.
Neurologic impairment occurs in different patients be-
tween 135 and 125 1nEq/L Na+. Fluid restriction to 10
rnl/kg body weight is in order (700 ml/24 hr). Judicious
sodium repletion may be undertaken by the adrninistra—
tion of 3 to 5 percent of hypertonic saline solution. Of
course, ﬂuid must be restricted simultaneously (73).
Future Trends
Several therapeutic maneuvers show promise in aneu-
rysm surgery and in the evaluation and treatment of va-
sospasm. As software is improved, MRI angiography
may allow direct, repeated visualization of the intracra-
nial vasculature, allowing early detection of vasospasm
and its response to treatment (74).
New surgical procedures (especially the orbitocranial
approach) provide exposure of the aneurysm with neghgi—
ble brain retraction, and new endovascular procedures
hold much promise. Balloon catheters can now be in-
serted into small vessels to allow trapping or direct occlu-
sion of both anterior and posterior circulation aneu-
rysms (75,76,77). Platinum coils and foreign bodies
made from other thrombogenic material may allow per-
cutaneous thrombosis of certain aneurysms, particularly
those not readily or safely accessed by open operation
(Fig. 9 A and B) (78,79). Balloons may be used for angio-
plasty to dilate vasospastic vessels including distal
branches (Fig. 10 A and B) (80,81,82,83).
Volume expansion and hemodynamic aids have pro-
vided the most effective means to augment perfusion
deficits that occur with vasospasm. Recently, fine sili-
cone balloons attached to ﬂow—directed rnicrovascular
catheters have been introduced into the cerebral circula-
tion for the direct relief of cerebral vasospasm. Zubkov
pioneered this approach and has accumulated a series of
over 100 patients. The carotid artery and middle cere-
bral artery appear to be the most easily dilated, but other
intracranial vessels may also be accessible. The dilata-
tion has effectively relieved both the radiographic con-
striction and the associated clinical ischemia. Complica-
tions have included premature rupture of aneurysms,
disruption of intracranial vessels, and worsening of isch—
ernia. We currently employ balloon dilatation after early
aneurysm clipping when the patient develops a deterio-
rating clinical course and findings of TCD sonography or
cerebral angiography indicate possible vasospasm.
Because the subarachnoid clot may initiate the cere-
bral vasospasrn that occurs after aneurysm rupture, it is
reasonable that removal of this clot would prevent the
development of vasospasm or ameliorate the condition.
Some surgeons have attempted to evacuate the clot at
operation, but these procedures have shown hrnited suc-
cess because often the thrombosis is remote from the
surgical site. More recently, thrombolytic agents have
been used. Currently, trials are underway to evaluate re-

ANEURYSMS AND CAROTID—CAVERNOUS FISTULAS / 49
FIG. 9. A,B: This large basilar apex aneurysm, partly filled with thrombus, could not be clipped using
conventional methods without sacrificing the posterior cerebral arteries. Ten platinum coils were packed
into the aneurysm with a balloon oocluding the neck to prevent embolization. There was good thrombo-
sis of the aneurysm fundus with improvement in neurological status.
FIG. 10. A,B: Cerebral vasospasm successfully dilated by balloon angioplasty. Clinical signs stabilized.

50 / CHAPTER 4
combinant tissue plasminogen activator (rtPA) for disso-
lution of the subarachnoid clot. As expected, the agent is
not a panacea and some vasospasm continues to occur.
Bleeding complications have also been described. In ani-
mal experiments, rtPA, even though it hastens dissolu-
tion of the subarachnoid clot, does not prevent the arte-
rial injury as measured by the intimal platelet reaction
(unpublished material and personal communication,
Dr. Y. Yamamoto).
Conclusions
Operative clipping provides the best long—term pre-
vention from rebleeding from an intracranial aneurysm.
The timing and interim management of those in whom
operation is deferred is controversial. Perhaps as many
patients are lost owing to rebleeding during the waiting
period as are saved by waiting for the subarachnoid space
to clear of blood and for improvement in grade. Bed rest
with moderate blood pressure control is probably the
most effective interim management method in patients
in whom operation is to be deferred. Vasoconstriction is
a complicated problem, and no answers are available
yet. Much more must be known about the healing pro-
cess of the cerebral vessel and what factors are responsi-
ble for the constrictive angiopathy that often develops
after SAH.
In patients of advanced age and in those with compli-
cating rnedical disorders or difficult or inaccessible aneu-
rysms, nonoperative therapy may be the only alterna-
tive. Alert patients may be operated on within 48 hours
of their first hemorrhage to avoid recurrent hemorrhage.
At the same time, some increase in morbidity because of
postoperative vasoconstriction may occur. It is not yet
known whether this risk is greater, equal to, or less than
the risk of rebleeding.
With persistent efforts, the lesion responsible for SAH
can be identified in the vast majority of cases. This may
require CT scanning and four—vessel angiography, per-
haps combined with cerebral blood ﬂow studies or 1nag—
netic resonance studies of the head or spine. No gains are
to be made from a passive approach in managing the
patient with a recent SAH. The severity of this illness,
along with its tendency to recur, justifies an aggressive
attempt to establish a prompt and accurate diagnosis.
CAROTID ARTERY—CAVERNOUS SINUS
FISTULAS
Rupture of the carotid artery within the cavernous
sinus results in a carotid—cavemous ﬁstula. Trauma is
responsible for almost every case in individuals under 40
years of age, but in older age groups spontaneous corn-
munications sometimes develop. The condition should
not be confused with fistulas developing spontaneously
between the external carotid artery system and the cav-
ernous sinus in older individuals. The external carotid-
dural malformations usually resolve spontaneously; the
need for treatment of these lesions has not been settled.
The internal carotid artery lesion, however, rarely re-
solves spontaneously; more often it results in blindness.
Occasionally death has been reported, but few post1nor—
tem studies are available. In the spontaneous variety,
perhaps small aneurysms or weakness of the muscular
layer causes rupture of the carotid wall. In the traumatic
variety, the disruption presumably occurs secondary to
bone fracture and laceration of the artery within the
sinus. Nowhere else in the human body does a large ma-
jor artery, such as the internal carotid, pass through a
venous sinus. Arterial blood escapes into this channel,
thus gaining entry into the superior ophthalmic veins.
These veins ultimately exit in the superior eyelid, coin-
municating with the facial vein and draining into the
jugular system. Posterior drainage ﬂows through the infe-
rior and superior petrosal veins, the sigmoid and lateral
sinuses, and, finally, into the internal jugular vein. Flow
in the ruptured internal carotid artery escapes through
the cavernous sinus, but the ﬁstula may draw on all avail-
able sources. Thus blood frorn the opposite internal ca-
rotid aitery, the vertebrobasilar system, the intracranial
portions of the carotid artery, and the meningeal vessels
may ﬂow into the low—pressure sinus (84).
Signs and Symptoms
A loud, continuous, machinery—like bruit is the most
common symptom described and usually begins a short
time after injury. Within a few days, exophthahnos and
proptosis become pronounced on the side of the fistula.
Occasionally, both cavernous sinuses are affected and
bilateral proptosis is observed (85). The proptosis may be
associated with pulsations of the globe, although in the
early stages of a carotid—cavemous ﬁstula, the eye must
often be viewed from the lateral position in order to de-
tect these feeble movements. The bruit, usually detect-
able before the pulsations are noticed, can readily be
heard with a stethoscope or often with the unaided ear.
The TCD allows identiﬁcation of the abnormal ﬂow pat-
tern, even when the bruit may not be audible. Ocular
muscle paralysis may be associated with the fistula, and
there is often congestion and thickening of conjunctiva.
Neovascularization of the cornea takes place with new
tortuous vessels extending almost to the lirnbus, but
never over the corneal surface. The chemosis may cause
grotesque changes of the lids and periorbital area (84).
An alarming degree of impaired vision occurs with
carotid—cavemous fistulas. In most patients, impairment
of acuity is attributable to loss of retinal circulation.
Among untreated patients, only about 11 percent retain
normal vision. The reasons for visual loss are complex.

ANEURYSMS AND CAROTlD—CAVERNOUS FISTULAS / 51
The fall in ophthalmic artery pressure secondary to the
fistula and an increase in venous pressure in the retinal
vascular bed cause reduced retinal blood ﬂow. The result
is chronic hypoxia of cells in the retina. Secondary glau-
coma complicates 30 to 40 percent ofthe cases. Intraocu—
lar pressures of up to 60 1n1nH g have been recorded and
are sufficient to block retinal circulation entirely (84). In
addition to the changes in the visual system, other corn-
plications may occur. Recurrent severe epistaxis, stern-
rning from neovascularity in the nasal mucosa, may lead
to anemia and even death. Other patients may experi-
ence transient ischemic episodes because of the stealing
of cerebral blood ﬂow in the enormous fistula.
Treatment
The history of the treatment of this lesion parallels
that of the development of neurosurgery as a distinct
clinical specialty. During the earliest period. Sugar and
Meyer suggested occlusion of the venous outflow (86).
Shortly thereafter, however, ligation of the internal and
external branches of the carotid artery became standard
treatment (86). Dandy recognized that carotid ligation
allowed the fistula to continue siphoning blood from the
intracranial system and advised a trapping procedure by
ligation of the internal carotid artery in the neck and
intracranially above the fistula (87). Mason and co-
FIG. 11. A: Large carotid—cavernous fistula with filling of the
ophthalmic veins; B: Balloon inflated and detached in the cav-
ernous sinus; and C: Posttreatment angiogram shows obliter-
ation of the fistula and preservation of the carotid circulation.

,52/CHAPTER 4
workers further deﬁned treatment by adding ophthalmic
artery occlusion to the regimen (85). Recurrent proptosis
and return of the bruit were noted in a high incidence
even after the most complete of these procedures, and
visual loss was still the primary complication. In 1964,
this led Hamby to outline a procedure utilizing intracra-
nial carotid and ophthalmic artery clipping followed by
ernbolization of the internal carotid artery (88). The
common internal and external carotid arteries were li-
gated after muscle had been ernbolized into the fistula.
Using cardiopulmonary arrest. Parkinson was the first to
successfully execute a direct attack on the fistula. In the
final phase of this operation, the cavernous portion of
the carotid artery was opened and packed with 1nus-
de(89)
The shortcoming of all these operative approaches is
that in each case, the retinal artery pressure and the cir-
culation of the eye are further reduced. Because retinal
Bchenuaisthernostconnnoncauseofbhndnessandthe
primary indication for therapy in the first place, the ca-
rotid and ophthalmic arteiy circulation must be pre-
served, not ﬁnther ccunpronnsed.]Debrun and co-
workers developed an ingenious approach utilizing
detachable balloons to fill the cavernous sinus and block
the fistula (90). Their original technique called for inﬂat-
ing a balloon with Conray to establish its proper loca-
tion, then replacing the iodinated material with silicone
rubber, which was allowed to harden within the balloon.
Thebaﬂoon,auachedtothecaﬂnﬁerbyziﬂhconerubber
string, was then detached by sliding a seoond catheter
over the first, displacing the balloon into the fistula (90).
This technique, which has now been proven successful
in a number of hands, is the first to allow the carotid and
retinal circulation to be spared (Fig. 11 A, B, and C).
Still, in almost one-third ofthe cases, the carotid circula-
tion rnust be sacriﬁced, but this can be accomplished
percutaneously by inﬂating a balloon in the cavernous
carotid artery. At present, detachable balloons should be
the primary therapy for the carotid-cavernous fistula. Ca-
rotid artery occlusion, trapping, and all other operative
procedures are physiologically unacceptable alterna-
tives. The procedure should be performed by experi-
enced hands because cornplications due to ernbolization
occur frequently.
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CHAPTER 5
Princi [es of Neiirasurgm;
edit by Robert G. Grossman. R0senberE© 1991.
Published by Raven Press. Ltd.. New Yor .
Cerebral Arteriovenous Malformations
Henry D. Garretson
Pathology, 55
Clinical Presentation, 58
Natural History, 58
Diagnostic Tests, 58
Indications for Surgery
and Therapeutic Alternatives, 59
PreoperativeManagen1ent,59
Cerebral arteriovenous malformations (AVMS) are devel-
opmental anomalies resulting from one or more direct
arteriovenous (A—V) shunts of congenital origin. The ar-
teries and veins associated with these shunts are not
aberrant vessels but rather pait of the normal vascular
tree. Characteristically, the artery proximal to the shunt
slowly and passively enlarges, secondaiy to the high—ﬂow
volume resulting from the lack of significant peripheral
resistance. The normal venous drainage channels receiv-
ing the direct arterial inﬂow becoine enlarged and
tortuous as a result of the abnormally high—ﬂow volume
and the elevated local venous pressure resulting from the
direct artery to vein connection. These lesions occur
with equal frequency in both sexes, with no evidence for
genetic predisposition (1,2). The incidence of this anoin-
aly in the general population is estimated to be approxi-
mately 0.14 percent of the U.S. population.
PATHOLOGY
The classiﬁcation of vascular diseases of the central
nervous system has undergone progressive evolution
with the increasing knowledge of the anatomic and physi-
ological features of these lesions in viva, resulting first
from the development of cerebral angiography and more
recently further refined by knowledge acquired through
direct inicrosurgical experience with these lesions. The
first major classiﬁcation of intracranial vascular 1nalfor—
mations, used extensively in the older European litera-
H. D. Garretson: Division of Neurological Surgery, Depart-
ment of Surgery, University of Louisville School of Medicine,
Louisville, Kentucky 40292.
55
Einbolization, 59
Immediate Preparation, 61
Operative Management, 61
PostoperativeManagen1ent,62
Outcome, 63
References, 63
ture, consisted of four general categories: angioma caver-
nosuin, angioma racemosum, angiorecticuloma, and
angioglioma (3,4). Under angioma racemosum were
placed the subheadings telangiectasis, Sturge—Weber syn-
drome, angioina racemosum arteriale, angioma race1no—
sum venosuin, and arteriovenous aneurysm. The cate-
gory aiteriovenous aneurysm, described in a somewhat
confusing fashion as a mass of inextricably entwined ves-
sels resembling aiteries and veins, corresponds to our
current classiﬁcation of aiteriovenous malformation.
In 1966 a more clinically oriented classiﬁcation was
proposed by McCormick (5). He divided intracranial vas-
cular anomalies into five pathological types: telangiecta-
sia, varix, cavernous angioma, venous angioma, and a1te—
riovenous malformation. Telangiectasia refers to
relatively common, typically small, solitary capillary an-
gioinas that are only occasionally associated with he1nor—
rhage. The most common sites of telangiectasia are the
pons and the roof of the fourth ventricle. Varix refers to
small lesions, frequently not grossly visible, consisting of
one or more dilated veins not associated with an a1terio—
venous shunt. These lesions may occur either in the par-
enchyma or in the leptomeninges and may be associated
with hemorrhage, occasionally massive. The term cavern-
ous angioma is applied to lesions consisting of dilated
sinusoidal vascular spaces varying in size from 1 mm to
several centimeters in diameter. They occur in all paits
of the central nervous system, although they are found
most frequently in the cerebmm. The sinusoidal vascu-
lar spaces are not separated by brain parenchyina. Both
calcium deposition and hyalinization of the vessel walls
are common, and spontaneous thrombosis of all or pait

56 / CHAPTERS
of the lesion may occur. Clinically they are associated
occasionally with severe hemorrhage as well as with sei-
zures. They are not associated with abnormal shunting
of aiterialized blood into the sinusoidal plexus. Venous
an gi omas quite closely resemble the more common arte-
riovenous malformation, except that they are not asso-
ciated with an arteriovenous shunt and do not contain
arterialized blood. These malformations consist entirely
of veins and are somewhat more common in the spinal
cord than in the brain.
The final group, arteriovenous malformations, is the
primary topic of this section. Arteriovenous malforma-
tions originate as a congenital maldevelopment ofblood
vessels that occurs between the fourth and eighth weeks
of embryonic life, with preservation of one or more prim-
itive direct arteriovenous communications between oth-
erwise normal arterial and venous channels. They occur
most commonly in the cerebral hemispheres, with re-
ported series ranging from 70 percent to 93 percent inci-
dence in supratentorial structures (1,2,6,7). The middle
cerebral arterial tree is the most frequently involved arte-
rial field, with percentages ranging over 50 percent in
most larger series, followed in declining frequency by the
anterior cerebral and then the posterior cerebral arteries.
These lesions may be restricted to the epicerebral or
transcerebral circulation or may involve both. The epi-
cerebral circulation consists of short perforating arteries
that break up into capillary plexuses within the cortical
gray matter, with the draining veins coursing immedi-
ately back to the pial surface (8,9). Arteriovenous mal-
formations restricted to the epicerebral circulation have
a characteristic angiographic appearance (Fig. 1). Mal-
formations involving the transcerebral arteries may not
be visible on the cortical surfaces. Involvement of the
transcerebral circulation produces a characteristic py-
ramidal or wedge—shaped angiographic and gross patho-
logical appearance, with the apex of the wedge directed
toward the subependymal venous plexus of the lateral
ventricle (Figs. 2 and 3). The base of the wedge is parallel
to the outer convexity of the hemisphere. The transcere-
bral veins, which have a primary outﬂow pattern to the
subependymal venous plexus, also have anastomotic
connections with the cortical pial veins. It is therefore
common to see enlarged arterialized venous channels on
the cortical pial surface participating in the outflow from
a transcerebral arteriovenous shunt. Arteriovenous mal-
formations involving branches of the proximal posterior
cerebral arteries may result in massive dilatation of the
Vein of Galen and have frequently been referred to as
"aneurysms of the vein of Galen." A rare but surgically
favorable arteriovenous malformation that occurs is ap-
plied to the lateral aspect of the brain stem and lies en-
tirely external to the pial surface. This lesion can be sur-
gically resected without interference or damage to the
brain stem circulation (10).
There is an increased incidence of saccular or berry
aneurysms in patients with arteriovenous malforma-
tions. In most series this incidence is approximately 10
percent, with the aneurysm usually occurring on one of
the major feeding arteries to the malformation
(1,7,11,12). The findings of a cooperative study, how-
ever, were somewhat at variance with this, with 37 per-
cent of aneurysms associated with arteriovenous malfor-
mations on the feeding artery and 43 percent unrelated
to the anatomy of the arteriovenous malformation (1).
Aneurysms on the proximal feeding arteries tend to de-
crease in size after removal of the malformation and may
completely disappear (13).
The smaller arteriovenous malformations tend to en-
large gradually with time (14). This enlargement consists
V "r B
FIG. 1 . (A) Lateral and (B) A—P angiographic views of right rolandic AVM of the epicerebral circulation.

CEREBRAL ARTERIOVENOUS MALFORMATIONS / 57
FIG. 2. (A) Lateral and (B) A—P angiographic views of left sylvian AVM showing typical wedge shape of
transcerebral circulation involvement.
of passive dilatation of the proximal feeding arteries,
with progressive ballooning and increasing tortuosity of
the draining venous channels. Structural changes have
been observed in the walls of the feeding arteries in older
age groups, with increased collagen deposition in the
muscularis and associated loss of smooth muscle fibers
(13). Fragmentation and loss ofthe internal elastic mem-
brane of the arterial wall are also seen in older patients.
These structural changes are of possible importance in
understanding some aspects of the postoperative course
in the older age group.
Within the malformation, large thin—walled vascular
FIG. 3. Right posterior frontal AVM involving transcerebral
circulation draining into and massively enlarging the subepen—
dymal venous plexus.
channels are found of a histologically indeterminant
character, neither artery nor vein. The muscularis is
poorly developed, with irregular areas of intramural cal-
cification often seen. Gliosis of the brain parenchyma
commonly occurs around the lesion, becoming more
prominent with each decade of life. Prominent cloudy
arachnoidal thickening in the immediate vicinity of and
over the older malformations is a characteristic finding.
There is little or no neuronal parenchyma within the
interstices of the malformation. Functioning neural tis-
sue does not reside with the malformations. Some degree
of cerebral atrophy can often be seen around the irnrnedi—
ate margins of the larger lesions in older patients. Cere-
bral steal by the low resistance A—V shunt with attendant
local ischemia and/or small occult hemorrhages asso-
ciated with the malformation may be responsible for
these atrophic features.
The presence of an open communication between an
otherwise normal cerebral artery and an adjacent venous
outﬂow channel results in a sump effect, with an abnor-
mally high ﬂow developing in the feeding artery because
of the absence of normal peripheral resistance. The nor-
mal branches leaving the parent artery just proximal to
the arteriovenous shunt are therefore presented with
lower—than—normal perfusion pressure (15). The circula-
tion is shunted away frorn these vessels with normal cap-
illary beds and normal peripheral resistance into the low-
resistance sump of the arteriovenous shunt (16). This
cerebral steal has been demonstrated by nondiffusible
(mercury 197) and diffusible (xenon 133) radioisotopic
cerebral blood—ﬂow techniques as well as by fluorescein
angiography (17,18). The hypoperfusion of the normal
parenchyma around the margins of the AVM produced

58 / CHAPTERS
by this cerebral steal undoubtedly accounts for at least
some of the nonlrernorrhagic clinical manifestations as-
sociated with arteriovenous malformations, such as sei-
zures arrd deterioration of intellectual performance.
CLINICAL PRESENTATION
Irrtracrarrial hemorrhage and seizures are the two most
common modes of presentation, and they occur with
approximately equal frequency (1,12). However, series
reported from some centers with a major surgical orie1rta—
tion may show up to a 70 percent incidence of hemor-
rhage as the initial event. No consistent relationship be-
tween physical activity arrd rupture of the malformation
has been found. The vascular disruption responsible for
the hemorrhage most probably occurs just distal to the
locus of the arteriovenous shunt within the rnalforrna—
tion. Seizures associated with arteriovenous rnalforrna—
tions are usually focal in nature, with respect to both the
electroencephalogram and the clinical pattern of seizure.
The average age of onset of seizures as the initial syrnp—
tom is 25 years, as contrasted to 30 years for hemorrhage
(19). Headache is the next most common presenting
complaint, occurring in o1re—tl1ird of patients. Intellec-
tual deterioration irr the later stages of the clinical evolu-
tion of large arteriovenous malformations, probably sec-
ondary to cerebral steal, may also be seen (4,20,21). In
addition, hydrocephalus secondary to recurrent hernor—
rhages and a pseudotumor syndrome, produced by irr-
creased pressure irr the major dural venous sinuses irr-
duced by the arterial shunting, may occur. High—output
congestive heart failure, as a result of a cerebral arteriove-
nous fistula or malformation, is a common presenting
clinical picture in infants and has occasionally been seen
in older age groups. Although seizures and hemorrhage
tend to occur with approximately equal frequency as the
initial clinical picture, large arteriovenous rnalforma—
tions (greater than 7 cm) are twice as likely to present
with seizures, and small malformations (less than 7 cm)
are at least twice and possibly three times as likely to
present with hemorrhage (22). An increased risk ofhem-
orrhage during pregnancy has been suspected, but docu-
mentation irr this regard has been contradictory and irr-
conclusive.
NATURAL HISTORY
Rare instances of spontaneous disappearance of an ar-
teriovenous malformation have been reported, although
the usual clinical evolution exhibits one or more aspects
of progressive pathophysiology (14,19,23,24—26). Pa-
tients with seizures but no previous hemorrhage run a
risk of hemorrhage of between 2 and 3 percent per year
(19,27). Mortality from an initial hemorrhage from an
AVM is approximately 10 percent, as compared to 12
percent for a second hemorrhage (1). In a series of 35
patients presenting with seizures alone who were fol-
lowed over an average of 15 years, there was a 17 percent
mortality and a 20 percent severe disability secondary to
hemorrhage (19). These patients were found to have a 25
percent chance of intracranial hemorrhage over the 15-
year period. If a patient had had one hemorrhage, there
was a 25 percent chance ofrebleed within four years, and
if a patient had had two bleeds, the risk of further rebleed
was 25 percent within the following year. Kjellberg's
analysis of the cooperative study statistics on 495 i1rtra—
cranial arteriovenous malformations indicated an over-
all incidence of rebleed of 3.7 percent per year, with a
death rate of 0.9 percent per year (11). Herbs and Tu
have concluded that the risk of bleeding from an AVM is
3 percent per year or 25 percent in 15 years (28). In the
cooperative study, mortality increased with each hemor-
rhage, with a 10 percent mortality from the first bleed, 13
percent from the second, and 20 percent from the third.
Troupp's follow—up analysis of 137 patients treated corr-
servatively with a follow—up ranging from a minimum of
10 years to a maximum of 25 years found that only 27 of
the 137 were well at the end of the study, with 51 patients
dead from or severely disabled by the arteriovenous inal-
formation (26).
DIAGNOSTIC TESTS
Magnetic resonance imaging is the most accurate
screening test for arteriovenous malformations of all
FIG. 4. MRI scan showing characteristic "signal voids" of a
small left occipital AVM.

CEREBRAL ARTERIOVENOUS MALEORMATIONS / 59
sizes. Current high—resolution units clearly show "ﬂow
voids" corresponding to the enlarged feeding arteries as
well as the engorged draining veins of even quite small
lesions (Fig. 4). Biplane, preferably stereoscopic,
arteriography remains the definitive presurgical study
for delineation of the detailed arterial inflow and major
venous outﬂow pathways. Magnification angiography
and subtraction studies often supply valuable additional
detail not visible on conventional films. Accurate knowl-
edge of the relevant arterial and venous anatomy is es-
sential for surgical decision making. The electroencepha-
logram is helpful in guiding and monitoring clinical
management in patients with seizures secondary to an
arteriovenous malformation. In these patients, the elec-
troencephalogram characteristically shows epileptiform
abnormalities in the cortical areas immediately border-
ing the malformation.
INDICATIONS FOR SURGERY
AND THERAPEUTIC ALTERNATIVES
Any form of management must yield better therapeu-
tic results than the natural history of the illness for the
treatment to become widely accepted (29,30). Parallel-
ing major technical strides in the surgery of intracranial
aneurysms from new techniques and methodologies in
anesthesiology and from the introduction of the operat-
ing microscope, similar advances have taken place in the
ﬁeld of arteriovenous malformation surgery. Combined
surgical mortality and major morbidity figures of less
than 10 percent are now being achieved, lending new
impetus to more aggressive surgical approaches to these
lesions (1,4,27,31—33).
Conventional high—voltage radiation has had only spo-
radic reported success in inﬂuencing the evolution of
these lesions. The focused stereotactic linear accelerator,
"gamma knife," or proton beam Bragg peak methodol-
ogy appear to have their greatest effectiveness in lesions
with small—caliber feeding arteries. There is usually a de-
lay of 18 to 24 months before a therapeutic effect of the
radiation can be demonstrated angiographically. The
large cortical arteriovenous malformations usually show
little if any change after any form of radiation therapy.
Obliteration rates for malformations under 3 cm in diam-
eter with smaller feeding arteries initially were reported
to be between 65 and 80 percent in carefully selected
series (34). More recent data reported by Kjellberg indi-
cates total obliteration in 22 percent and "nearly total"
obliteration in an additional 29 percent (35).
Flow—directed silastic—pellet or Ivalon—sponge emboli-
zation of the feeding arteries to the malformation has
made a major contribution toward their subsequent sur-
gical removal (36,37). However, except for rare in-
stances, neither of these techniques nor the use of intra-
vascular detachable balloons placed in the feeding
arteries, nor, more recently, the inj ection of rapidly poly-
merizing plastic or "glue" introduced through a ﬂow-
directed catheter passed into the feeding artery, has been
curative by itself (1 1,38). Complete occlusion ofthe arte-
riovenous malformation using one of these techniques
has not usually been possible, and reduction of the size of
the arteriovenous malformation has not given protec-
tion against subsequent hemorrhage (36).
Current surgical techniques have begun to yield a bet-
ter 5-year prognosis than the natural history of the lesion
for patients presenting with an initial hemorrhage, and a
competitive 10-year prognosis for patients presenting
with seizures alone (39,40). The age and general health
of the patient therefore plays an obvious and signiﬁcant
role in the decision with respect to further management.
Patients under the age of 40 presenting with intracranial
hemorrhage should be encouraged to have their lesions
removed if they are surgically accessible. Patients under
the age of 40 presenting with seizures should give serious
consideration to the relative risks of the natural history
of their lesions in relation to the operative results of the
neurosurgical team seeing them in consultation. Surgical
morbidity and mortality for large lesions increase after
the age of 40 (13). If the lesion is to be excised, there is a
major advantage to having it done in the earlier years of
one's life. In addition, the psychological effect on the
patient of living with the knowledge of the ongoing risk
of intracranial hemorrhage often has a major inﬂuence
on the patient's overall sense of well—being.
PREOPERATIVE MANAGEMENT
Embolization
Early neurosurgical approaches to arteriovenous mal-
formations usually utilized an en—bloc removal of the
lesion along with a significant portion of the lobe in
which the malformation was located. This made proxi-
mal control of the arterial inﬂow to the lesion easier and
resulted in a much shorter surgical procedure, a factor of
some signiﬁcance in the earlier days of anesthesia. It also
provided significant decompression for postoperative
swelling and congestion. In larger arteriovenous malfor-
mations it has become recognized as important to re-
duce as far as possible the hydraulic shock produced by
clipping the larger feeding arteries. Sudden occlusion re-
sults in an abrupt rise, from lower than normal to higher
than normal, in the intraluminal pressure ofthe enlarged
arteries proximal to the lesion. The resultant vasocon—
gestion is particularly critical in the management of mal-
formations in areas of critical or eloquent function. Hy-
draulic shock and attendant vasocongestion appear to be
more of a problem as the patient's age advances (13).
Characteristically, in the late teens and early twenties,
the vessels proximal to an A—V shunt return rapidly to

60 / CHAPTERS
normal caliber within the first 8 to 10 postoperative
days. The expected interval of transient cerebral swelling
in these individuals is usually quite brief. The older age
groups, especially after the fourth decade, show much
slower return of the proximal vessels to normal caliber.
This slow return causes more persistent hi gher—than—nor—
mal perfusion pressures around the margins of the re-
moval. Closing off these enlarged arteries by staged or
sequential surgery was initially used to reduce the impact
of this phenomenon on the patient's postoperative
course (41).
Luessenhop's technique of catheter—introduced ﬂow-
directed silastic—pellet embolization of these larger le-
sions, with pellet sizes ranging from 1 mm up to as large
as 3 mm, has taken the place of staged surgical occlusion
and has been successful in achieving the desired goal
(Fig. 5). A minimum period of three to six weeks is al-
lowed to pass after the last embolization, with repeat
arteriography immediately before the planned surgery.
Opening up of new vascular channels over this time in-
terval has not been found. This technique has provided a
useful buffer with respect to phasing the circulatory read-
justment required by obliteration of these lesions
(16,42).
The rapidly polymerizing intraluminal glues are less
satisfactory for this purpose for three reasons. First, they
are not as readily adaptable to graded sequential closing
off of the arterial inﬂows to these lesions. Second, and
perhaps more important, intravascular glue carries a
greater risk of occlusion of the normal side branches to
cortical areas of critical function. These normal
branches often depart from the parent artery after the
parent artery has begun to make a major contribution to
the malformation. Finally, unmalleable rocklike solidifi-
cation of the malformation can increase the risk and
technical difficulty of surgical excision, particularly in
FIG. 5. Patient, 28 years old, with attempted AM removal
three years previously, showing progressive reduction in cali-
ber of major middle cerebral arterial feeder with embolization.
(A) Before silastic—pelletembolization; (B) 1 Oweeks after sec-
ond—stage embolization (13 weeks past first stage); and (C)
1 0 days postoperatively.

CEREBRAL ARTERIOVENOUS MALFORMATIONS / 61
the central or rolandic areas where rigid prongs represent-
ing the malformation vessels on the immediate margins
of the main lesion may be coursing deep into, through,
or over areas of critical function. The anatomic course of
these vessels would in some instances make the lesion
surgically unexcisable if the veins, solidified by the poly-
merized glue, could not be easily and gently sectioned or
divided on the immediate margin of the malformation.
Immediate Preparation
Immediate preoperative patient preparation includes
steroids, anticonvulsants, and careful counseling with
the patient and the family as to what to expect during the
early postoperative period. Starting anticonvuls ant inedi-
cation preoperatively, regardless of the presence or ab-
sence of antecedent seizure history, is probably advisable
to help insure against a seizure during the expected early
postoperative cerebral swelling stage. Serum anticonvul-
sant levels should be checked before surgery. Steroids,
started 24 to 48 hours preoperatively, are used in many
centers to help maintain stability of capillary membrane
permeability during the early postoperative hydraulic
shock and associated vasocongestive phase.
OPERATTVE MANAGEMENT
Arteriovenous malformations are usually excised
under general anesthesia with the patient's head stabi-
lized with Gardner pin fixation. The surgeon must take
care to position the head to ensure optimal venous drain-
age, keeping the area of the malformation well above
heart level (31,43). A combination of the anatomic loca-
tion of the malformation and the patient's presenting
symptoms and signs may suggest the importance of be-
ing able to test speech or motor function during the re-
moval of the lesion (44,45). In this situation the proce-
dure can be done under local anesthesia, utilizing a
regional field block of the scalp with the patient's head
elevated on a comfortable soft cushion. The resection is
always carried out on the immediate margin of the inal-
formation. It is essential that the dissection be done
under magnification with microsurgical instrumenta-
tion to obtain optimum clinical results with minimal
blood loss. Careful stepwise isolation and occlusion of
the individual small transcerebral draining veins are es-
sential if blood loss is to be minimized. These very thin-
walled vessels, if not carefully identified, occluded with
the bipolar cautery, and divided under magnification,
can produce excessive blood loss. Ifinadvertently torn,
they can be extremely difficult to seal off, oozing briskly
and tempting the surgeon to pursue them on into the
adjacent tissue. These thin—walled tubules (Fig. 6), when
torn, carry arterialized venous backﬂow from the sub-
ependymal venous plexus under increased pressure.
Placement of small fluffy cotton pledgets over the point
of bleeding will normally stop the bleeding within two to
three minutes. Preservation of normal channels of ve-
nous drainage will significantly reduce postoperative
morbidity and neurologic deficit and should always be
attempted. Identification of the arterial inﬂow to the
malformation, with preservation of the venous outﬂow
for as long as possible during the course of the resection,
significantly reduces blood loss and permits a maximum
degree of protection and preservation of the immediately
adjacent cortical and subcortical structures. The bipolar
cautery must not be relied upon as the sole agent in se-
curing occlusion of arterial feeders approaching 1 mm or
larger in size. Vessels of this caliber must be securely
clipped if delayed postoperative hemorrhages are to be
avoided.
When working under local anesthesia, one maps
speech and motor functions using a biphasic square-
wave physiologic stimulator before commencing resec-
tion of the lesion. Sequential temporary clipping of the
feeding arteries is then carried out. If the patient tolerates
temporary clipping without developing a neurologic defi-
cit, the temporary clips are replaced with permanent
clips and the resection continued. Cortical mapping per-
mits an initial approach to the malformation along the
cortical margins of maximum safety for the patient (Fig.
7). Identification of areas of critical function has been
done using a proportional grid system projected over the
arterial and venous phases of the lateral and anteriopos—
terior angiographic studies (46). This technique pre-
sumes that motor and speech functions will not be
shifted from their usual locations by the malformation.
Cortical mapping with a physiological stimulator pro-
ducing a 2—millisecond square wave, at 60 cycles per sec-
ond monopolar stimulus has unfortunately shown this
to be quite frequently not the case.
When the resection is begun, mild hypotension (at a
mean arteiial pressure in the range of 63 to 70 torr, 1nea—
sured at the level of the cerebral cortex) is helpful. This
degree of hypotension has been maintained for up to 14
hours without adverse effect. Blood pressure and heart
rate are controlled with titrated levels of triinethaphan
and propranolol. Depending on the stage of resection
and the dryness of the field, blood pressure should be
intermittently allowed to rise by 5 to 10 torr from the
lowest mean tolerated levels. Patients under local anes-
thesia tolerate this degree of hypotension without cloud-
ing of mental alertness or interference with testing of
cortical function.
Identification of the location of the malformation
when subcortically situated is normally not a problem,
given good—quality preoperative angiographic studies ac-
companied by the usual presence of aiterialized venous
drainage leading the surgeon directly to the malforma-
tion. Intraoperative intracarotid injection of high—con—
trast visual dyes of the type used for cardiac output stud-

62 / CHAPTERS
ies, such as Evans blue, may be used to identify the
feeding arteries visually when they are obscured by and
difﬁcult to differentiate from a dense tangle of irnrnedi—
ately adjacent draining veins (47). It is an occasionally
frustrating aspect of arteriovenous malformations that
they seem to maintain their fragility or propensity to
bleed down to the last one or two fine feeding vessels.
The transcerebral veins, as previously noted, are very
fragile, and the area of involvement with the enlarged
draining veins of the subependymal venous plexus must
be handled very gently if brisk bleeding from these struc-
tures is to be avoided.
After completion of the resection, the operative ﬁeld
should be observed carefully to ensure that hemostasis is
complete. If the blood pressure has been lowered, it
should be gradually brought up to normal levels to err-
sure that hernostasis is complete and to reduce the risk of
FIG. 6. (A) and (B) dilated, thin-walled transcere-
bral veins near subependymal venous plexus of a
transcerebral AVM.
postoperative bleeding. A danger to be aware of is the
potential risk of a proximally propagating clot in the oc-
cluded arterial feeders to the malformation. In dealing
with small posterior fossa arteriovenous malformations,
such proximal intraluminal clot propagation may be po-
tentially lethal. There is unfortunately no good preve1r—
tive measure for this other than the gentle handling of
tissues during the resection.
POSTOPERATTVE MANAGEMENT
Postoperatively, the principal aspects of management
involve the control of ﬂuid intake, maintenance of 1ror—
mal circulating blood volume, control of arterial pres-
sure, steroid administration, arrd anticonvulsant ther-
apy. For the ﬁrst 48 hours postoperatively, elevation of
the patie1rt's head at 30 to 40 degrees assists in rnai1rtai1r—

CEREBRAL ARTERIOVENOUS MALFORMATIONS / 63
FIG. 7. Left posterior sylvian AVM after cortical mapping.
Points 1 , 2,4, and 5 represent face and tongue, and points 7,
8,1 0, and 1 1 representspeech.
ing an optimal venous outﬂow. Monitoring and mainte-
nance of systolic arterial pressure between 90 and 110
torr using a trimethaphan—camsylate drip also helps pro-
tect against the effects of hydraulic shock and attendant
hyperperfusion around the margins of the resection.
Fluid intake should be moderately restricted, with a goal
of producing and maintaining serum osmolarity be-
tween 295 and 305 mOsm/Kg. Sequential 20—gram
doses of mannitol administered intravenously may be
used to help achieve and maintain the desired osmolar—
ity. Blood—volume maintenance in the face of the above
dehydration program is best achieved with fresh frozen
plasma. Dexamethasone at a dosage level of 16 to 32 mg
per 24 hours in divided doses is given for 7 to 10 days
postoperatively and then rapidly tapered. Follow—up
postoperative angiography is essential to ensure that the
malformation removal is indeed complete.
OUTCOME
In a current consecutive series of 89 patients who un-
derwent angiographically confirmed complete surgical
resection of an arteriovenous malformation, the preced-
ing techniques have permitted removal of the lesion with
an average blood replacement of less than one unit and a
maximum replacement of seven units (31). Most of
these lesions were quite large and existed predominantly
in the rolandic parasylvian areas. In this group of pa-
tients, there has been one postoperative death from ful-
minant hepatic necrosis. This patient's intraoperative
and postoperative course was unremarkable from a neu-
rological standpoint. All patients except one, who has
mild residual memory and speech problems, have re-
turned to their regular preoperative activities and occu-
pations. There have been two additional deaths in our
larger surgical series, which includes patients undergoing
procedures other than surgical removal. Survival—rate
statistics for either conseivative or surgical management
of arteriovenous malformations have only limited
meaning unless careful attention is given to the quality
of the suivival as well. Surgical results currently being
achieved in the major centers active in vascular malfor-
mation surgeiy are beginning to be significantly more
favorable than those of the natural histoiy of conserva-
tively treated arteriovenous malformations. The effect of
surgical removal of an AVM on patients in whom sei-
zures are the presenting problem is less clearly defined
and must await longer follow-up, although a reduction
in seizure frequency in most recent series is beginning to
be repoited in the literature (5,30).
Current results indicate that careful microsurgical re-
section of arteriovenous malformations when techni-
cally feasible is the treatment of choice in the manage-
ment of cerebral arteriovenous malformations.
REFERENCES
1. Ferret G, Nishioka H. Report on the cooperative study ofintracra-
nial aneurysms and subaraclmoid hemorrhage. Section VI. Arterio-
venous malformations. An analysis of 545 cases of cranio-cerebral
arteriovenous malformations and fistulae reported to the coopera-
tive study. J Neurosurg 1966;25:467-490.
2. Pool JL, Potts DG. Aneurysms and Arteriovenous Anomalies of the
Brain: Diagnosis and Treatment. New York: Harper and Row,
1965.
3. Bergstrand H, Olivercrona H, Tonnis W. Gefassmissbildungen
and Gefassgeschwulste des Gehirns. Leipzig: George Thieme Ver-
lag, 1936.
4. French LA, Chou SN. Conventional methods of treating intracra-
nial arteriovenous malformations. Prog Neural Surg 1969;3:274—
319.
. McCormick WF. The patholog of vascular (“arteriovenous")
malformations. J Neurosurg 19 6;24:807-816.
. Chou SN, Erickson DL, Ortiz-Suarez HJ. Surgical treatment of
vascular lesions in the brain stem. J Neurosurg 1975;42:23-31.
. Michelsen WJ. Natural history and pathophysiology of arteriove-
nous malformations. Clin Neurosurg 1979;25:307-313.
. Saunders RL de, Feindel WH, Carvalho VR. X-ray microscopy of
the blood vessels of the human brain. Med Biol Illus 1965; 15: 108-
122.
9. Saunders RL de, Feindel WH, Carvalho VR. X-ray microscopy of
the blood vessels of the human brain. Med Biol Illus 1965;15:234-
246.
10. Drake CG. Surgical removal of arteriovenous malformations from
the brain stem and cerebellopontine angle. J Neurosurg 1975;
43:661-670.
1 1. Drake CG. Cerebral arteriovenous malformations: Considerations
for and experience with surgical treatment in 166 cases. Clin Neuro-
surg 1979;26:145-208.
12. Stein BM, Wolpert SM. Arteriovenous malformations of the brain.
1: Current concepts and treatment. Arch Neural 1980;37:l-5.
13. Garretson HD. Posto erative pressure and flow changes in the
feeding arteries ofcere ral arteriovenous malformations, (abstract)
Neurosurgery 1979;4:544-545.
14. Waltimo 0. The change in size of intracramal arteriovenous mal-
formations. J Neural Sci 1973; 19:21-27.
15. Barnett GH, Little JR, Ebrahim ZY, Jones SC, Friel HT. Cerebral
circulation during arteriovenous malformation operation. Neuro-
surgery 1987;20:836-842.
OO\]C\U1

CHAPTER 6
Principles 0f"atmair en:
edited by Robert G rassman. Rosenbng c 1991
Published by Raven Press, Ltd.. New Yak.
Spontaneous Intracerebral Hematomas
Howard H. Kaufman
Introduction, 65
Epidemiology, 65
Etiologies, 66
Path0physi0l0gy,67
Hypertensive, 68
Supratentorial, 68
Infratentorial, 7 1
Nonhypertensive, 73
Aneurysm, AVM, 73
INTRODUCTION
Spontaneous intracerebral hernatornas (SICHs) are clots
that arise without immediately preceding trauma. They
may be prirnary—that is, not due to other speciﬁc dis-
ease except indirectly as in the case of hypertension—or
secondary, caused by a variety of congenital and ac-
quired conditions.
Many changes in the population and in health care
must be kept in mind when considering the incidence of
SICHs. Their etiology, and therefore epidemiology, is
changing owing to factors ranging from the improved
treatment of hypertension to the increased use of co-
caine. Clots can now be accurately diagnosed by cornput—
erized tomography (CT) or magnetic resonance imaging
(MRI), making it possible to evaluate incidence more
precisely. However, until all patients in large popula-
tions suffering strokes are studied with neuroirnaging,
autopsy, or both, the true incidence will not be known. A
large number of victims of ICH die immediately or pre-
sent comatose and subsequently die (1). Prevention is
the ultimate solution of the problem, but the question,
given the current situation, is how to optimize care. Ani-
mal studies have led to a better understanding of the
pathophysiology of SICH. Human studies have sug-
gested the possibility of improved methods of treatment,
H. H. Kaufman: Department of Neurosurgery, West Vir-
ginia University, Morgantown, West Virginia 26506.
65
Coagulopathies, 73
Tumors, 73
Vasculopathy, Vasculitis, 74
Drugs, 74
Postoperative, 74
Poststroke. 74
Delayed Posttraurnatic, 75
Postinfectious Aneurysm, 75
References, 76
including controlling intracranial pressure and evacuat-
ing the hernatornas with either open or stereotactic sur-
gery.
With this growing interest, the literature dealing with
SICH has rapidly proliferated and includes two recent
monographs (2,3), several overview chapters in texts (4-
13), review articles in journals (14-17), and literally
hundreds of limited chapters and clinical and basic re-
search articles published in the last few years. Despite
this work, there is much more to be learned about the
problem. This chapter is meant to incorporate classic
teaching as well as current developments and to stirnu—
late further interest in this subject. A truly critical review
of the literature would require a book of several volumes.
EPIDEMIOLOGY
The epidemiology of SICHs is difficult to determine.
There have been many clinical and pathological studies,
and these have been well summarized (17,18). It would
appear that stroke is the third most common cause of
death in the United States, causing 2 to 4 percent of all
deaths. SICHs are the cause of 10 to 20 percent of strokes
and 15 to 20 percent of deaths owing to strokes. Hyper-
tension is the rnost common single factor contributing to
SICHS, with arnyloid angiopathy beginning to assume
more significance as the population ages. Many SICHS
are large and prove fatal, although when populations of

66 / CHAPTERS
stroke victims are screened, many small hematomas are
found. The incidence of all strokes, including SICH, is
declining in parallel with the more frequent detection
and effective treatment of hypertension (19).
Attempts to be more precise are problematic for many
reasons. To understand the incidence of SICHs properly
would require national figures to eliminate population
biases, and all cases would have to be diagnosed and
contributing factors identified. But some bleeds are rnin—
imally symptomatic and not reported (as has been noted
with subaraclmoid hemorrhages). Small bleeds may be
thought to be infarcts if CT scans are not done (20-22),
and large bleeds may be diagnosed but their cause not
identified (e.g., bleeds into the basal ganglia from aneu-
rysms). Patients may die suddenly from bleeds but not
be autopsied, and their deaths may therefore be attrib-
uted to other causes [bleeds are thought to cause 10 to 15
percent of sudden deaths (23)]. On the other hand, pa-
tients may die of such problems as cardiac disease and be
thought to have suffered SICH. Regional variations in
populations with regard to race, age, and socioeconomic
factors as well as changes in medical knowledge and
practices explain the tremendous variations described in
the epidemiologic literature but, unfortunately, do not
fully clarify the true epidemiology of the SICH.
ETIOLOGIES
A unified theory for the etiology of SICH has been
proposed based on an acute increase in blood ﬂow in
areas of normal or ischemic arterioles or capillaries (or
other vessels) or damage to penetrating blood vessels by
chronic arterial hypertension (24). This can be applied to
most specific etiologies. Larger vessels may also be sub-
ject to weakening, or insignificant acute injuries may fail
to seal in the face of bleeding diathesis.
Table 1 outlines the etiologies of SICHs. There are
some obvious overlaps. For example, the bleeding diath-
esis in disseminated intravascular coagulation contrib-
utes to delayed posttraumatic SICH, and anticoagulants
contribute to bleeds after cardiac surgery related to ern—
boli which cause infarction and then lyse, leading to
bleeding. Also, trauma and infection lead to aneurysms.
The etiologies listed below amyloid angiopathy in the
table are probably uncommon. Part of the "unknown"
group may include many patients in whom bleeding was
caused by a functional problem, with acute rises ofblood
pressure caused by stress of various types.
As already mentioned, the most common cause of
SICH is chronic hypertension (22), and incidence is re-
lated to the degree of elevation of the blood pressure (25).
A predisposition to hypertension, which has been noted
in Japanese and blacks, and socioeconomic problems
that have prevented detection and treatment within cer-
TABLE 1 . Etiologies
Incidence Trend
Hypertensive
Chronic (Acute) +
Not hypertensive
Congenital vascular anomalies
Aneurysms
AVMs
Coagulopathy —
Tumors
Vasculopathy, vasculitis
Cerebral amyloid angiopathy
Moyamoya
Vasculitis
Drug related
Sympathomimetics +
Anticoagulants —
Fibrinolytics +
Postoperative
lntracranial —
Carotid —
Cardiac
Poststroke
Arterial infarction —
Venous occlusion
Delayed posttraumatic
Parenchymal
Aneurysmal
Postoperative
Postinfection aneurysm
Neonatal intraventricular"
Other
Unknown/none
Secondary brainstem" —
a Not considered.
tain groups may explain the high incidence of SICHS in
certain populations (4). The incidence of fatal bleeds is
actually many times greater in Japan than in the United
States, which probably accounts for the high level of in-
terest, aggressive approach, and numerous studies corn-
ing frorn that country. However, although hypertension
is implicated in some series in as many as 90 percent of
SICHs, this may not be completely accurate and may be
changing dramatically (26). There is a male predorni—
nance, and age plays a role. Alcohol intake and, speciﬁ-
cally, cirrhosis seem to predispose an individual to
SICHs. Atherosclerosis and smoking may contribute as
well (4).
The other speciﬁc causes of SICH will be considered in
more detail subsequently. However, to put these issues
in perspective, an approximation of frequency is given in
Table 1. The future trends in the incidence of these prob-
lems are also projected, based on assumptions that are
fairly apparent [i.e., increased use of street drugs, aging
of the population with more common bleeding from
amyloid angiopathy, less use and better control of antico-
agulants, treatment of disseminated intravascular coagu-
lation (DIC) to avoid delayed traumatic SICH].

PATHOPHYSIOLOGY
The bleed leading to the development of ICH is related
to one or a combination of the following: vascular
weakening, increased stress on the vessel wall, and irn—
pairment of hemostatic mechanisms.
The vasculopathy of chronic hypertension is well de-
scribed (9). For whatever reason, the small branches (50
to 200+ / um) that arise at right angles to the trunks of the
penetrating vessels develop a speciﬁc abnormality (lipo-
hyalinosis), which in turn can cause either a scaning (fi-
brohyalinosis) or miliary aneurysms that can rupture.
Target arteries include the lenticulostriates, the thalamo—
perforates, and paramedian branches of the basilar ar-
tery, as well as the superior and anterior—inferior cerebel-
lar arteries. Many other known causes can lead to weak
or damaged vessels. For example, damage to the paren-
chyma may compromise support to the vessels, although
the signiﬁcance of this is not clear. Acute increases in
blood pressure/ﬂow may also be important, particularly
when autoregulation may be compromised, as in
trauma, or when pressure may be above the limits of
autoregulation, as in toxemia. Last, hemostatic mecha-
nisms may be compromised, as is found in delayed trau-
matic SICH, bleeding diathesis, and following the use of
anticoagulants.
In hypertensive hematomas, the bleeding event is rela-
tively acute (27). Small satellite hemorrhages, which
may contribute to the enlargement of the clot, may be
seen owing to secondary disruption of more distant
small vessels. Some authors believe that this is a very
important mechanism in the development of clots
(2,28—3l). The blood pressure (systemic and local), size
and rigidity of the vessel involved, state of autoregula-
tion, state of the hemostatic system, and physical condi-
tion of the surrounding parenchyma probably all play a
role in determining the size of the bleed.
The ultimate clinical manifestations of the clot relate
to the speed and volume of the bleed as well as to its
location (Fig. l). A small bleed may dissect along tissue
planes, splitting the tissue apart rather than destroying it.
Such a bleed will generally produce limited compromise,
restitution of function when the blood is absorbed, or
both (32). A very large bleed may explode into the brain
MASSIVE BLEED
ICP > BP
HERNIATION MODERATE BLEED
LOCAL DESTRUCTION
DEATH LOCAL PRESSURE
CHEMICAL IRRITATION
BRAIN "CREEP"
SMALL BLEED
BRAIN SPLIT
MINIMAL IMPAIRMENT,
DETERIORATE IMPROVE
OR IMPROVE,
DEFICITS
FIG. 1. Spectrum.
SPONTANEOUS INTRACEREBRAL HEMATOMAS / 67
TABLE 2. Distribution of hypertensive hemorrhaqes
Trend
Basal ganglia 35% +
Subcortical white matter 25%
Thalamus 20% -
Cerebellum 1 0% —
Pons 5% +
substance, destroying large amounts of tissue, raising in-
tracranial pressure to the level of the blood pressure be-
fore the bleeding is tarnponaded, and causing herniation
of the brain from its normal position under the falx
through the tentorium or through the foramen magnum,
depending on the location of the bleed. With posterior
fossa bleeds, there may be direct compression of the
brainstem. Basal ganglia clots of more than 85 cc or
more than 6 percent of the volume of the brain and cere-
bellar clots more than 3 cm in diameter have a poor
prognosis if untreated. Blood may rupture into a ventri-
cle and even cause hydrocephalus, but on the other
hand, this may actually decompress the clot. Blood may
also find its way into the subarachnoid space, causing
irritation and even hydrocephalus. Distortion of the up-
per brainstem may also lead to hydrocephalus.
There may be subsequent mechanisms that lead to
further problems. Even if there is not acute herniation,
the brain is plastic and can further deform or "creep"
because of pressure from the original mass. It is now well
known that blood is irritating to the parenchyma, caus-
ing a progressive hemorrhagic necrosis with edema at the
margin of the clot (33). Human and animal studies have
revealed changes in local and distant blood ﬂow and
changes in metabolism following ICH (34).
If the patient lives, the clot will eventually be broken
down and absorbed, leaving only a cavity with walls con-
taining hemosiderin—laden macrophages. In the case of a
large clot, this will take many months.
It is traditional to consider SICH in abipartite fashion.
Because perhaps as many as 80 to 90 percent of hemato-
rnas are caused by hypertension, and because most of
these occur in typical locations (Table 2) (9,l8,26), this
group will be considered first by site. The remaining he-
rnatornas are those that often originate in the subcortical
white matter, and the etiologies of these will be consid-
ered separately. However, this is an oversimplification,
as indicated in Table 3. Although it is true that subcorti-
TABLE 3. Relation of hypertension to location
Hypertension No hypertension
75 to 50%+ 25 to 50°/o-
Basal ganglia 65% 35%
Subcortical white matter 45% 55%
Thalamus 75% 25%
Cerebellum 62% 38%
Rons 90% 10°/o

68 / CHAPTERS
cal clots may have a variety of speciﬁc etiologies, a large
proportion (45 percent) may still be related to hyperten-
sion. On the other hand, clots in locations typical for‘
hypertensive bleeds may often be due to other causes.
For example, clots in the pons may be due to such prob-
lems as cryptic AVMs. Of course, hypertensive patients
may have clots caused by speciﬁc etiologies.
HYPERTENSIVE
Supratentorial (4,6—l0,l2,35—38)
Statistics
Supratentorial hematomas constitute about 80 per-
cent of SICHs, and perhaps one—half are related to hyper-
tension. Their highest incidence is in the fifth (and sixth)
decades. Males may predominate. The distribution of
these hemorrhages has already been noted (Table 2).
They may be divided into gangliobasal and lobar. Gan-
gliobasal hematomas may occur in the basal ganglia or
thalamus. Those in the basal ganglia may be internal or
deep (f), or external or superﬁcial (I), depending upon
their relationship to the internal capsule. This classifica-
tion may have considerable surgical signiﬁcance. Lobar
hematomas tend to be seen in younger patients. One-
third are due to hypertension. Aneurysms and AVMs are
frequent causes, as are tumors and coagulopathies. In
almost one quarter, there is no obvious etiology at the
time of presentation.
Symptoms and Signs (4,6,9,39,40)
Clinical manifestations relate to the location of the
clot, size and rapidity of evolution, and secondary her-
niation as well as to ventricular and subarachnoid exten-
sion with hydrocephalus and meningeal irritation. An
excellent grading scheme based on level of consciousness
has been developed (4l,42) (Table 4). Presentation may
be abrupt and acute, with an altered level of conscious-
ness and progression to death within hours to days, in
one—third to one—half of cases (although this is not a cer-
tain figure and reports vary considerably) (6). On the
other hand, with small hematomas in eloquent brain,
there may be only focal signs with full preservation of
consciousness.
Initial symptoms of a hypertensive Supratentorial
bleed may include headache, nausea, vomiting, and al-
tered consciousness. Seizures may be seen but are not
common. Symptoms and signs depend on origin, direc-
tion, and degree of extension.
In putaminal hemorrhages, motor deficits predo1ni—
nate over sensory abnormalities. Depending on extent,
other symptoms will include frontal gaze paresis, hom-
TABLE 4. Level of consciousness
Grade
111-3 formula
1
Grade I The patient is awake without
any stimulus
(1 ) 1 is seemingly alert but not fully so
(2) 2 is disoriented to time, place, and person, or
(3) 3 is quite senseless and cannot tell even his or
her own name or date of birth
Grade II The patient is able to be aroused with
mechanical or verbal stimuli
2
(10) 1 is aroused easily with usual voice
3
(20) 2 is aroused with loud voice or shaking
shoulders, or
3
(30) 3 is barely aroused with repeated mechanical
stimuli
Grade III The patient is unable to be aroused
with any forceful mechanical stimulus
4a
(100) 1 is responsive with combative or purposeful
movements
4b
(200) 2 is responsive with slight movements including
decerebrate response, or
(300) 3 is not responsive at all except for change of
respiratory rhythm
onymous hemianopsia, aphasia (if the dominant hemi-
sphere is involved), and constructional apraxia and
hemi—neglect (if the nondominant hemisphere is in-
volved). A CT grading scheme has been developed (41)
(Table 5). Caudate hematomas are less common and
tend to be more benign. They do, however, often extend
into the lateral ventricle and cause hydrocephalus.
Speciﬁc symptoms of thalarnic hemorrhages include
sensory deﬁcits, herniparesis (if the internal capsule is
involved), oculomotor and pupillary disturbances (ow-
ing to extension into the brainstem), extrapyramidal
motor disturbances, a dysphasia characterized by ﬂuctua—
tion and paraphrasia (if the dominant hemisphere is in-
volved), and neglect (if the nondominant hemisphere is
involved). Thalamic pain syndromes and hemisensory
strokes may be seen. Speciﬁc syndromes have been de-
scribed for small hemorrhages. A CT grading scheme has
been developed (41) (Table 5).
The clinical picture of lobar hematomas depends on
their location and extent. Seizures are more common
and coma less common than in more deeply lying hema-
tomas. The clinical pictures of these lesions have been
described and depend, again, on their site of ori gin, direc-
tion of spread, and size.
An outcome grading scheme has been developed (Ta-
ble 6).

TABLE 5. CT classification of basal ganglionic and
thalamic hemorrhage
Class Type
Basal ganglionic hemorrhage
l Ex. C. Localized outside the intern;
capsule
ll Ca Extending to anterior limb
Ilia Cp withoutV Extending to posterior limb
lllb Cp with V with massive ventricular
hemorrhage
lVa Ca + p without V Extending to anterior and
posterior limbs
lVb Ca + p with V with massive ventricular
hemorrhage
V Th Extending to thalamus or
subthalamus
Thalamic hemorrhage
la Localized in thalamus
lb with massive ventricular hemorrhage
lla Extending to internal capsule
lib with massive ventricular hemorrhage
llia Extending to hypothalamus or midbrain
1Mb with massive ventricular hemorrhage
Diagnostic Studies (43)
The general laboratory evaluation indicated in SICH
may be extensive. Besides routine admission studies,
there should be evaluation of the heart, peripheral ves-
sels, and kidneys. The cause of hypertension might be
investigated in patients with elevated blood pressure.
Screening for hematologic abnormalities, infectious pro-
cesses, and vasculitides may prove useful. The presence
of primary intracranial lesions, including tumors and
congenital vascular abnormalities, must be kept in
mind.
The most critical laboratory evaluation for the investi-
gation of SICH is the CT scan, both in terms of initial
diagnosis and in surgical planning. Because of the high
density of blood, hematomas just a few millimeters in
diameter can be seen. Indeed, recent studies have shown
that many strokes formerly believed to be caused by in-
farction are really due to hemorrhages (44). In addition,
details about the hemorrhage, including the exact loca-
tion, size, associated brain shift, ventricular extension,
and secondary hydrocephalus, aid in surgical planning
and may improve prognostication and the understand-
ing of the pathophysiology involved. Contrast infusion
may provide additional information about primary le-
sions and may be indicated in patients (1) less than 40
years of age, (2) without hypertension, (3) with neuro-
logic impairment increasing for more than four hours,
(4) with history of neoplasm, blood dyscrasia, vasculitis,
or bacterial endocarditis, or (5) with blood in the sub-
araclmoid space or with an atypical location or appear-
ance of the clot (22).
SPONTANEOUS INTRACEREBRAL HEMATOMAS / 69
Angiography may also be indicated when a primary
lesion is suspected. It provides evidence of mass effect in
over 75 percent of SICH and can confirm the diagnosis
of a primary lesion such as tumor, aneurysm, or AVM.
Because edema as well as clot can contribute to mass
effect, the volume of the clot may be overestimated by
angiography. Conversely, when the brain is split, the an-
giographic changes may not fully reﬂect the size of the
clot.
MRI is not generally used in ill patients with large clots
because most life support equipment has magnetic com-
ponents and cannot be used in MRI machines. Also,
acute clots have magnetic characteristics similar to the
brain and may not image well, although associated le-
sions such as AVMs or tumors may be visualized better
on MRI than on CT scan. Clots are better visualized on
MRI after a few days.
Natural History
Only one—third of patients present with an abrupt on-
set. Many of the rest do deteriorate; progression usually
reaches its maximum within 48 hours. Most who die will
do so within a few days (4,6,7).
The patient's subsequent course may be one ofdeterio—
ration, improvement, or even improvement with subse-
quent deterioration. Comatose patients with large clots
can be expected to die (21). Those with marked focal
neurological deficits and moderately sized clots will sur-
vive with significant deficits. It is thought that most sur-
vivors are left with deﬁcits, many of which may be inca-
pacitating. Patients with mild deficits and small clots will
recover.
Overall ﬁgures suggest that more than 50 percent of
hospitalized victims now survive (4). This may be attrib-
uted both to more frequent identification of small clots
and to improved treatment (21). Level of consciousness,
the size of the clot and accompanying shift, and ventricu-
lar rupture are the most imp oitant prognostic indicators.
Thalamic clots have the worst prognosis. Older patients
fare worse. Delay in treatment is harmful (6,8).
The change in the CT appearance of the heinatoina
has been studied extensively (6—8,43). With time the clot
becomes isodense as its chemical composition alters. An
area of "ring enhancement" develops around the 1nar—
gins ofthe clot, probably caused by edema and inﬂa1n1na—
tion. There are a number of staging schemas for both CT
TABLE 6. Postoperative evaluation of patients
ADL
1 Well (full work)
2 Minimal disability (work, self—sufficient)
3 Partial disability (semi-self-sufficient)
4 Total disability (bed—ridden)
5 Vegetative
6 Died

70 / CHAPTERS
(41) (Table 5) and MRI changes with various time
frames emphasized. There is eventual resolution of
edema and resorption of the hematoma. Small clots (<2
cm) are absorbed especially rapidly. Edema dissipates
more slowly than clots resorb, but this is difficult to
study in detail because the clot itselfbecomes more radio-
logically isodense (45).
General Treatment
For severely affected patients, comprehensive rnanage—
ment in an ICU setting seems warranted, especially to
prevent the cardiac and pulmonary complications that
often contribute to death.
Although hypertension should be controlled, there are
risks of compromising cerebral blood ﬂow with too low a
blood pressure in the face of increased intracranial pres-
sure. On the other hand, too high a pressure risks in-
creasing edema. The difficulty in patients with chronic
hypertension is that autoregulation may be altered with
regard to the blood pressure required to sustain ﬂow. It is
really not possible to determine the blood pressure re-
quired to optimize cerebral blood ﬂow, given the gener-
ally available technology.
Intracranial Pressure Monitoring and Treatment
A French—Italian study demonstrated that patients
with poor neurological status had a high ICP. However,
some patients without high ICP did die, presumably
from local damage. Some patients with intermediate neu-
rological status had increased ICP while others did not.
Early surgery seemed to help reduce ICP and improve
outcome, but not delayed surgery. Patients in good clini-
cal condition had low ICP (46-48). Other authors have
reported that ICP monitoring permits optimal medical
management of the patient (6,49), as well as guiding the
surgeon as to whether or not surgery is necessary (50,51).
S urgery
There are two reasons for actually removing hemato-
mas: to preserve life and to maximize recovery of func-
tion. Both may be threatened by the mass effect of the
clot and progressive edema and tissue damage. As a re-
sult of the work of McKissock and his colleagues in the
early 1960s, which suggested that early surgery might be
injurious (38), there has been a relatively passive attitude
about these lesions during the last two decades, and very
little research has been done into their pathophysiology
in the English—speaking countries. But investigators in
Japan, Europe, and South America have advocated a
more surgically oriented approach and have even devel-
oped innovative techniques for the evacuation of basal
ganglia, thalarnic, and brainstem clots (52-54).
Surgery is not indicated in the face of irreversible neu-
rologic damage suggested by a greatly depressed level of
consciousness, rapid clinical deterioration, or a massive
hematoma, and it is generally not needed in patients
who are alert and have hematomas less than 2 cm in
diameter. Some patients with clots between 2 and 3 cm
may beneﬁt from surgery (7). Critical size may also be 85
cc (6,56,57). One suggestion states that surgery is not
needed if the clot occupies less than 4 percent of the
intracranial space, should be based on the clinical status
if the clot occupies 4 to 8 percent, should be done if the
clot occupies 8 to 12 percent, and will not help if the clot
occupies more than 12 percent of the intracranial space.
Not all agree on these guidelines, and there are certainly
exceptions, such as life—threatening small clots in critical
areas, and surprisingly well tolerated large clots. If pa-
tients have not needed surgery by the 1 Oth day, deteriora-
tion is infrequent.
Since the 1930s, there has been a consensus that crani-
otomy and transcortical evacuation of clot is required
for satisfactory treatment of patients in the acute situa-
tion. If there is any question of the etiology of the hema-
toma, surgery should include biopsy of the wall of the
cavity for tumor or AVM. An interesting observation
made since CT has been available is that, with early sur-
gery, rnass effect may actually increase after evacuation.
Open surgery has been used for lobar hematomas with
considerable success. The general principles covering
skin, bone and dural incisions should be followed, and
careful, gentle technique, particularly with regard to he-
rnostasis, should be utilized. Approaches should be
made where the clot extends toward the surface or
through "silent" areas of the brain. Small amounts of
adherent clot may best be left undisturbed.
Surgery for deeper clots was viewed with considerably
less enthusiasm in the pre—CT era, although a few au-
thors reported encouraging operative results. It has long
been clear that simple aspiration is inadequate to treat
many such clots and that reliable removal can be
achieved only by craniotomy and corticectomy. A num-
ber of developments from the 1970s, however, make
only recent series relevant when trying to understand the
potential role of surgery. With modern neuroimaging,
diagnosis is rapid and the anatomy clear. Medical care in
an ICU setting can optimize cardiac and pulmonary
function. ICP monitoring and control (although this has
not been used frequently in SICH patients) are now avail-
able. Surgery itself has been facilitated by the develop-
ment of transtemporal and transsylvian approaches
(52,53,54), and modern technique includes the routine
use of magniﬁcation and good illumination as well as
gentle retraction. Clinical and CT grading scales (Tables
4 and 5) have been developed so that patients can be
compared from series to series. Contemporary experi-

mental design utilizes randomized clinical trials at best
or closely matched controls in prospective trials.
Some, although not all, of the recent literature is en-
couraging. For example, on the basis of matched con-
trols (410 surgical patients versus 204 medical controls),
Kanaya et al. believed that surgery was helpful in all
patients except those who were alert or only somnolent
(58). Using 165 medical controls for 187 surgical pa-
tients, Mizukami concluded only giade III (i.e., 1noder—
ately impaired) patients benefited from surgery (11).
Kanno and coworkers, using internal controls, thought
that moderate and severe cases who were operated on
did slightly better (N — 265). They did not come to a
conclusion with regard to thalamic clots (N = 135) (59).
Waga and colleagues, comparing 44 patients who had
surgery for putaminal hemorrhage with 130 who did not,
decided that surgery was actually harmful (60). Kaneko,
Koba, and Yokoyaina, who compared 100 patients with
putaminal hemorrhage who had ultra—early operations
with historical controls, believed that surgery was more
beneficial than conservative management or delayed
operations (53). On the basis of a combined study in
Japan using historical controls, Kanaya et al. thought
that surgery for patients with putaminal hemorrhage and
stupor, semicoma, or coma (A' = 3216) was definitely
helpful. They also recommended surgery for thalamic
hemorrhages (N = 639) (61).
Delayed surgery may be indicated in certain situa-
tions. Soine patients stabilize and then deteriorate, do
not improve, or improve only slowly. Several authors
have performed late operations on such patients with
encouraging results.
Additional formal and rigorous studies are needed to
define more precisely which patients should be managed
surgically and how to optimize treatment.
Aspiration
Aspiration of the clot would, on the face of it, appear
to be the simplest and therefore most attractive treat-
ment. Both freehand and stereotactic aspiration have
been studied in some detail (62). The effectiveness of
simple aspiration is, however, extremely unpredictable.
The percentage of the clot that can be aspirated is vari-
able, and it is not even certain the effect time has on
degree of lysis because there are conﬂicting reports. Fibri-
nolytic agents seem to help dissolve the clot, but again
the effect is unpredictable; in some cases complete lysis
takes several days. A number of increasingly sophisti-
cated mechanical devices to break up the clot and facili-
tate its aspiration have been developed. These show the
gieatest promise in facilitating the surgical removal of
deep clots. Techniques employing such devices and indi-
cations for their use should become generally available
within the next 5 to 10 years.
SPONTANEOUS INTRACEREBRAL HEMATOMAS / 71
Intraventricular H ematomas (4,6,16,63,64)
Almost 80 percent of intraventricular hematomas
(IVHs) are related to intracerebral hematomas. They are
usually caused by hypertensive bleeds, aneurysms,
AVMS, and even pituitary apoplexia (64). They are often
accompanied by slightly enlarged ventricles. One—third
of SICHs are accompanied by IVH, and these have a
higher mortality rate. The primary hematoma and dis-
ease process are probably more signiﬁcant than the IVH.
Headache, vomiting, confusion, decreased level of con-
sciousness, and hemiparesis (in the case of a secondary
bleed) are common clinical findings (65). The clots tend
to disappear by two weeks. Recent CT studies suggest
IVHs are more frequent than previously suspected, but
they often are not clinically significant. When clots are
symptomatic, intraventricular drainage (possibly bilat-
eral) may be useful, but the blood often occludes cath-
eters used for this puipose. If permanent hydrocephalus
develops, a shunt may occasionally be required. Intraven-
tricular thrombolytic therapy has been shown experi-
mentally to be useful and safe (66). Direct surgery has
not proven useful (64).
lnfratentorial
Cerebellum (4—7,16,17,24,38,67—73)
Cerebellar hematomas constitute about 10 percent of
SICHs, a proportion coincident with the volume ofbrain
in which they occur. Males seem to predominate. The
highest frequency is in the sixth through eighth decades.
Many of these hematomas are related to hypertension
and are thought to be due to vascular disease ofthe arter-
ies, especially the superior cerebellar artery, supplying
the dentate nucleus. There may be a left predominance.
A small number originate in the vermis. Those in the
younger age group may be related to vascular1nalfor1na—
tions. Anticoagulants are the second most common spe-
cific cause.
Many cerebellar hematomas are extensive and mp-
ture into the fourth ventricle and commonly also into
the subaraclmoid space. Secondary hydrocephalus may
develop in up to 75 percent. Death is probably due to
brainstem compression and tonsilar herniation.
Symptomatology is related to the rapidity of bleeding
and the size of the hematoma, as well as to compression
of the brainstem, upward and tonsilar herniation, 1'up-
ture into the fourth ventricle, and development ofhydro—
cephalus. Presentation may be relatively abiupt, sub-
acute with progression over various times, or subacute
with resolution. Symptoms and signs are protean and
include headaches; alterations in level of consciousness;
vomiting with or without nausea; dizziness; eye signs,
including changes in pupils and gaze abnormalities;

7 2/ CHAPTERS
dysarthria; and motor signs, both cerebellar and pyra1ni—
dal. The classic triad of signs includes appendicular
ataxia, ipsilateral gaze palsy, and peripheral facial weak-
ness. Two out of three of these findings are seen in 75
percent of patients (70). A classic three—stage evolution
has been described (74).
The differential diagnosis is again extensive and in-
cludes cerebellar infarction, brainstem hematoma or in-
farction, bleeding frorn an aneurysm or a tumor in the
posterior fossa, posterior fossa tumor, and acute laby-
rinthitis. Clinical diagnosis is often difficult. In one series
of 33 patients, 13 with cerebellar hemorrhages or infarc-
tions were diagnosed correctly, 10 were not diagnosed
initially, and 10 diagnosed as having cerebellar strokes
actually had other problems (75).
Diagnosis can now be readily made with CT scanning,
which can also be helpful in surgical planning (69). The
clot can be localized and other abnormalities, including
blood in the fourth ventricle, brainstem distortion, and
hydrocephalus. can be assessed. Angiography can dem-
onstrate rnass effect and may be employed if an AVM or
other speciﬁc lesion is suspected, particularly in a young
patient without a history of hypertension. Because of the
high risk of a vascular malformation rebleeding, surgery
should be considered even if the angiogram is negative
(76). If the patient is not too sick and MRI is possible, it
can provide evidence of vascular malformations and
previous bleeds and can more precisely define the
anatomy.
Treatment includes control of blood pressure and re-
spiratory support as needed. The indications for surgical
therapy are probably better defined in patients with cere-
bellar hematomas than in patients with hematomas in
other locations, and these indications are based on the
level of consciousness (77,78), clinical course, and the
size of the hematoma (78,79). All patients with clots 3
cm or larger should be considered for surgery. Those
with clots between 2 and 3 cm, if the level of conscious-
ness has altered, should also be considered, especially if
they suffer deterioration, because some patients may de-
compensate rapidly (12). If the patient does well for a
week, surgery is probably not necessary. In the past, the
use of ventricular drainage by itself has been discouraged
because of the risk of upward herniation. But in patients
with clots ofborderline size, and possibly in conjunction
with mannitol, this may be an alternate mode of treat-
ment.
Most patients without impaired consciousness will re-
cover. Indeed, CT scans have shown that clots tend to
disappear in two to six weeks. Excellent surgical results
with relatively low operative mortality have been de-
scribed in patients with only moderately depressed level
of consciousness. Occasionally, patients with marked al-
terations in level of consciousness, particularly if they
did not have too abrupt an onset and if operation was
performed promptly, have unproved with surgery. Some
patients with late deterioration or persistent deﬁcits may
also be helped by evacuation.
Although the guidelines for surgical treatment of cere-
bellar hematomas are probably better defined than those
for other locations, there may still be questions in those
patients who are quite ill but not in extremis or in those
who are doing relatively well but are not improving rap-
idly.
Brainstem (4,5,7,l2,l7,68,72,73,80,8l)
Brainstem hemorrhages tend to occur predominantly
in the pons, although hemorrhages in the midbrain and
medulla have been reported. Pontine hemorrhages con-
stitute about l0 percent of SICHS, far out of proportion
to the volume of brain involved. Males and females are
equally involved. The highest frequency is in the fourth
and fifth decades. Ninety percent are related to hyper-
tension and are believed to be due to vascular disease of
the penetrating branches of the basilar artery. Those seen
in younger patients without hypertension may be related
to cryptic vascular malformations, which are especially
common in the pons but probably account for less than
10 percent of such bleeds.
In one postmortem series, brainstem hematomas were
present unilaterally in the basis pontis (at times with
spread into the tegmentum) in 22 percent, in the basis
bilaterally in 56 percent, and in the tegmentum in 22
percent (two—thirds bilaterally) (80). Clots extended up-
ward, even to the thalamus, but infrequently downward.
The fourth ventricle was usually distorted. In 70 percent
of cases, there was rupture into the fourth ventricle. Ex-
tensive edema was often present, the cause of which was
not known. Local vascular disease was common, as was
evidence of other cerebrovascular and cardiovascular
disease.
Syrnptornatology is based on location, size, speed of
development, and rupture into the fourth ventricle and
subarachnoid space, as well as hydrocephalus secondary
to ventricular occlusion or compression of the fourth
ventricle and aqueduct. In the aforementioned postrnor—
tem series, the onset was abrupt in one—half. In 30 per-
cent of the cases, the initial symptom was severe head-
ache, usually posterior. Symptoms and signs included
alterations in the level of consciousness; abnormalities of
respiration, pulse, and blood pressure; hyperthermia;
motor abnormalities that were unilateral or bilateral
with posturing or paralysis; cranial nerve abnormalities,
including pupillary and gaze changes with ocular bob-
bing, vertigo, vomiting, dysarthria, and/or autonomic
dysfunction; and "seizures" thought to arise from the
basis pontis. The classic triad of meiosis, hypertherrnia,
and bloody CSF was seldom seen. The diagnosis was
suspected in only 25 percent of the cases; 75 percent of
the patients died within 24 hours (80).

Tl1e co1n1no11 prese11tatio11 of co1na witl1 11eurologic
devastatio11 involves a11 extensive differe11tial diag11osis,
including 1nassive l1e1norrl1ages i11 otl1er locatio11s as well
as posterior fossa infarcts a11d hypeitensive e11cepl1alopa—
thy. Definitive diagnosis ca11 be made witl1 CT scanning.
A11giograpl1y may be e1nployed if a vascular malforma-
tion is suspected. The diagnosis may also be n1ade
witl1 MRI.
Treat1ne11t should vary witl1 the condition of the pa-
tient. Most patients prese11t with a11 acute onset ofdevas—
tati11g symptoms a11d will die. One group l1as suggested
that opl1tl1al1nologic findings may be used to detect po-
tential suivivors as well as to deter1ni11e the size a11d loca-
tion of the clot (82). 111 patients believed to be salvage-
able, there should be immediate attention to respiratory
suppo1t a11d control ofblood pres sure wl1e11 needed. Ve11—
tricular drainage may be used if hydrocephalus is pres-
e11t, but the very presence of hydrocephalus may be a
1narker of a fatal bleed. A major question concerns the
role of direct surgery. O11 one hand, l1e1nato1nas l1ave
been followed by CT a11d l1ave been seen to resorb, occa-
sionally with good result (83). O11 the otl1erl1a11d, seve1al
cases, including a few with acute onset, l1ave been
thought to l1ave been successfully operated 011 through
the fourth ventricle or subte1nporally. Computed to1nog—
raphy might suggest the best route (81). Other series,
however, l1ave suggested that surge1y i11 the acute stage
does 11ot improve outcome (84,85). Biopsy of tl1e wall is
said to lead to deterioration (17). Collaborative studies
will probably be needed to define which patients are ill
enough to require surgery a11d yet are 11ot beyond hope.
Patients with persistent symptoms fro1n u11resorbed
clots might l1ave direct or stereotactic aspiration, a11d
ones with recurrent bleeds caused by vascular1nalfor1na—
tions should be co11sidered for open surgery.
Finally, the usefulness of rehabilitation for many
stroke victi1ns appears well established a11d 1nust be pur-
sued when the patient is stable.
NONHYPERTENSIVE
Aneurysm, AVM
These abnormalities are the seco11d most common
cause of SICHs. It is thought that, of aneurysms that
bleed, o11e—fiftl1 will l1ave a SICH, while o11e—l1alf of
AVMs that bleed l1ave a SICH (86). A history suggesting
sentinel bleeds or, i11 the case of AVMs, seizures, l1ead—
aches, or focal findings, as well as a younger age, may
increase the index of suspicion. Although so1ne a11eu—
rysms may cause clots i11 typical locatio11s, even basal
ganglia clots may originate from aneurysms, a11d there
1nust always be a high degiee of suspicion (9). Such le-
sions may be seen o11 enhanced CT scans, especially with
fi11e cuts that include the sites oftypical aneurysms. MRI
SPONTANEOUS INTRACEREBRAL HEMATOMAS 7
may also be helpful. A11giography should be utilized for
any patient with a SICH who would be a11 operative ca11—
didate (87). Repeat CT and MRI scans without a11d with
co11trast may also be helpful. Because of vasospasin a11d/
or compression that could prevent filling, repeat a11giog—
rapl1y may be necessary. Timing of surgery for the clot
1nust be governed by the state of tl1e patient. If tl1e cause
is a11 aneurysm a11d early surgery is required, the a11eu—
rysm should generally be clipped duri11g the initial oper-
ation, ifpossible, to prevent early rebleedi11g (12). If early
surgery is required for a clot caused by a11 AVM, it may
be judicious to carry out the definite operation at a later
setting, pa1ticularly if the surge1y for the AVM will be
lo11g a11d difficult, because the early rebleed rate is
thought to be small. If a suspicious area is seen i11 the
surrounding brain duri11g surgery, it should be carefully
biopsied (88).
Coagulopatl1ies (4, 13 ,89,90)
I11tri11sic abnormalities ofbleedi11g may be due to co11—
genital or acquired problems affecting platelets or the
clotti11g cascade. The first category includes hemophilia,
congenital afibri11oge11e1nia. idiopathic tl1ro1nbocyto—
pe11ic purpura. a11d sickle cell disease. Acquired dis-
orders include liver disease, leukemia, polycytl1e1nia
vera. l1ypoprotl1ro1nbi11e1nia. a11d disseminated i11trav as-
cular coagulation and ﬁbri11olysis. Dysfunction of clot-
ting factors a11d/or platelets ca11 obviously predispose to
ongoing bleeding after even minor trauma. Consultation
with regard to treatment of the primary disease process,
replacement of clotti11g factors a11d platelets, a11d deci-
sions about surgery based 11ot only 011 the acute but also
011 the ultimate prognosis of the patient are important.
With the risk of transmitting various diseases, pa1ticu—
larly AIDS, thresholds for prophylactic use ofblood prod-
ucts a11d accepted replacement levels are changing.
Tumors (4,6,l2,l3,26,9l—93)
Depending 011 the biases of the patient population,
tumors may be the third or fourth 1nost common speciﬁc
cause of SICHs, causing up to 10 percent i11 so1ne series
but far less i11 others. Tumor should be suspected ifthere
is a recent history of progressive neurological dysfu11c—
tion or headache, as l1as been repo1ted i11 o11e—l1alf of
patients. Metastatic tumors (melanoma, bro11cl1ogenic
carcinoma, or cl1oriocarci11o1na), glio1nas (especially
more malignant ones), a11d even benign tumors (1ne11i11—
gio1nas, pituitary tumors) l1ave presented as SICHs. Fac-
tors leadi11g to bleeding include hypeiyascularity a11d ab-
normal vessels, necrosis, a11d the tu1nor's ability to
invade vessels. CT abnormalities that may suggest a tu-
mor include a subcortical site, a11 unusual appearance of

74 / CHAPTERS
the hematoma with abnormally appearing tissue within
or adjacent to the clot, excessive edema or mass effect
adjacent to the clot and extending even across the 1nid—
line, and enhancement. An angiograrn may demonstrate
abnormal vessels. If surgery is carried out for any clot,
the cavity wall should always be biopsied.
Vasculopathy, Vasculitis (94)
Cerebral arnyloid angiopathy (CAA) is a disease of the
elderly in which arnyloid is deposited in the media and
adventitia of small and 1nediu1n—sized superﬁcial cortical
and leptorneningeal arteries. CAA is expected to be a
more common cause of SICHs as our population ages.
Seen in 10 percent of those in their 70s and in over 60
percent of people over 90, it leads to recurrent and rnulti—
ple superficial bleeds from the weakened vessels. CAA
has familial varieties, and it is also associated with a vari-
ety of diseases from Alzheimer's to dementia pugilistica.
The diagnosis must be made by biopsy or postmortem
examination. The prognosis is poor, and surgery is not
advised (4,6,7,9,10,26).
Moyamoya includes a specific condition or a syn-
drome resulting frorn various diseases causing occlusion
of proximal cerebral vessels. It is characterized by trans-
dural or posterior fossa anastomoses and by collateral
channels in the basal ganglia. Bleeding occurs from mi-
croaneurysrns in the vessels in the basal ganglia or from
secondary posterior fossa aneurysms (4).
Fibromuscular dysplasia may lead to aneurysms and
secondary SICHS (95).
There are both multisystem (systemic lupus erythe—
rnatosus. rheumatoid arthritis, giant cell arteritis) and
isolated (granulomatous angiitis) vasculitides that can
lead to vascular weakening and bleeding. The diagnosis
can be suspected when faced with the systemic disease
and confirmed by a picture of vascular stenoses and
narrowings on angiography (4,94).
Drugs
A number of over—the—counter drugs and sympatho—
mimetic street drugs, including amphetamines and co-
caine, may cause SICHs, generally after chronic abuse.
This may be due to elevations in blood pressure and/or
vasculitis. At times angiography will demonstrate the
Vasculitis in the 1nediu1n—sized and larger arteries. The
clots tend to arise in the subcortical white matter. How-
ever, the blood pressure elevations may also precipitate
rupture ofpre—existing aneurysms and AVMs. The arter-
itis will subside with cessation of drug use and steroids
(4,7,9,17,26,89).
Anticoagulants can lead to SICHS, especially if the
clotting times are especially prolonged (i.e., prothrombin
time greater than 1.5 times normal). The bleed may
evolve slowly and become very large. Related to age, hy-
pertension, head injury (even minor), and infarction, it
may be the cause of up to 10 percent of SICHs and may
be seen in up to 2 percent of patients on anticoagulants.
The parenchyma is the second most common site (after
the subdural space) of intracranial bleeding exacerbated
by anticoagulants, and bleeding tends to occur in the
lobar white matter or cerebellum. Treatment involves
normalizing the hemostatic system, with vitamin K in
the case of oral anticoagulants and protamine sulfate for
heparin. The outcome is often poor, and two—thirds will
die (4,7,26).
Thrombolytic drugs, particularly urokinase and tissue
plasminogen activator, are now being used more exten-
sively, particularly for coronary artery thrombosis.
SICHs have been identified as a complication of these
drugs (4). There is growing interest in using thrombolytic
drugs to treat cerebral vascular occlusion, and the risk of
SICH in these patients will be particularly high (96).
Postoperative
Bleeding after carotid endarterectomy, although it oc-
curs in well under one percent of operations, may be
devastating. Usually delayed a few days, it occurs espe-
cially after opening a severely stenotic artery that has
caused hypoperfusion, particularly if the artery supplied
an area of previous infarction. Postoperative hyperten-
sion with hyperperfusion exacerbates the risk, whereas
optimal control ofblood pressure minimizes it. Postoper-
ative anticoagulants or antiplatelet agents increase the
incidence (4,12,97,98).
Postcraniotomy bleeding probably relates to a number
ofproblems, including inadequate hemostasis, local and
generalized DIC, breakdown of autoregulation, postoper-
ative hypertension, and low intracranial pressure that
minimizes tamponade. In one series, such clots were
seen in 0.5 percent of 4,992 intracranial procedures, con-
stituting 60 percent of postoperative intracranial clots.
Of these 24 patients, eight died, and seven had a poor
outcome (99). Placement of monitoring devices through
the brain may lead to direct injury to vessels, which is
particularly dangerous in the face of DIC (100,101).
SICHs after cardiac operations may be related to a
number of factors unique to this kind of surgery, includ-
ing ernboli, arterial hypertension, increased venous pres-
sure, and the use of anticoagulants (4).
Poststroke
A small number, perhaps 10 percent or less, of bland
or "white" cerebral infarctions will become hemor-
rhagic, presumably due to reopening of the occluded ves-
sel and leakage of blood from the vessels damaged from
the ischemic insult (7,24).

It is well known that angiography must be done soon
after infarction if a high percentage of occlusions are to
be seen, indicating that normal fibrinolytic mechanisms
clear the vessels of emboli and thrombi responsible for
infarctions. It is actually somewhat surprising that hem-
orrhage does not occur more often. Anticoagulants pre-
dispose to this problem. Therefore, their use, even after
emboli of cardiac origin, must be carefully consid-
ered (102).
Venous/sinus thrombosis may be a complication of
dehydration or congestive heart failure, hematologic
problems, oral contraceptives, pregnancy, trauma, infec-
tion, or malignancies, including leukemia. Venous
thrombosis may involve the sagittal sinus, transverse
sinus, cortical veins, or cavernous sinus. Clinical mani-
festations depend on the extent of the thrombosis and
the degree of collaterals. There may be evidence of ele-
vated intracranial pressure with or without obvious focal
signs, depending on the sinus involved and the site ofthe
hemorrhage. Seizures may be a prominent event. Sagit-
tal sinus thrombosis can lead to SICHs, usually in the
parasagittal white matter bilaterally. CT and MRI ap-
pearance may be diagnostic for such occlusions because
of bilateral clots. There may be a defect in filling of the
sinus on contrasted CT or MRI. Angiography can help,
but venography is not necessary or worth the risk. Treat-
ment should be aimed at the underlying condition. The
use of anticoagulants in the face of a hematoma is prob-
lematic. There is a signiﬁcant mortality with such hemor-
rhages (4,10,90,103,104).
Delayed Posttraumatic (101)
The so—called delayed traumatic intracerebral hemato-
mas (DTICHs) are included because these hematomas
do occur spontaneously and differ from other etiologies
only in that the primary initiating factor, the injury, oc-
curs at a distinct point in time as opposed to being the
result of ongoing or progressive disease. There are actu-
ally three groups, depending on the vessel of origin: (1)
clots from traumatic aneurysms on larger arteries, (2)
classic DTICH from smaller arteries, and (3) clots from
venous injuries.
Traumatic aneurysms can be caused by penetrating
injuries or closed head injuries (Table 7), and they may
be "true," "false," or mixed. At times rupture, often fa-
tal, occurs within days after injury. Traumatic aneu-
rysms cause SICHs in 10 percent of cases. The aneurysm
may be detected by comparing a CT without contrast to
one with contrast. Angiography should be performed if
missiles or other objects have passed near major arteries.
Early prophylactic clipping is suggested.
Classic DTICHs occur in 1.3 to 1.7 percent ofpatients
with head injury judged significant enough to CT and in
2.3 to 8.4 percent of those with Glasgow coma scores less
SPONTANEOUS INTRACEREBRAL HEMATOMAS / 75
TABLE 7. Etiologies of traumatic aneurysms
Penetrating
Depressed fractures
Gunshot wounds
Knives, etc.
Iatrogenic
"Closed head injury"
Tethering
Supraclinoid carotid
Local injury
Anterior cerebral at falx
Middle cerebral at sphenoid ridge
Posterior cerebral at tentorium
Cortical vessels at adhesions
or in linear fracture
than or equal to 8. They are generally seen three to four
days after injury. A variety of mechanisms can play a
role in their development (Table 8). Decompressive sur-
gery may contribute to their formation by releasing tarn-
ponade in areas of contusion. Treatment must be individ-
ualized. Prognosis depends on the size and location of
the clot and on the previous condition of the patient.
Postinfectious Aneurysm (12,105)
Previously called "mycotic" aneurysms, most aneu-
rysms of infectious origin are secondary to bacterial in-
fections, particularly subacute bacterial endocarditis
(SEE). They are due to infected emboli that lodge in
distal intracranial aiteries, particularly the middle cere-
bral branches. Occurring in at least 4 to 10 percent of
patients with SBE, they are multiple in 20 percent of
patients. They may also be the result of meningitis and
septic cavernous sinus thrombophlebitis. They may
present as SICHs or subarachnoid hemorrhages or they
may be seen after infarction or may present just with a
headache. CT without and then with contrast may reveal
the aneurysm as well as the bleed. Workup should in-
clude total angiography. Initial treatment should include
antibiotics and correction of the cardiac lesion if indi-
cated. Based on a review of the literature, one group of
authors suggests the following:
TABLE 8. Primary and secondary factors leading to DTICH
Vessel damage
Neuropil damage
Vasospasm
Vasodilatation
Vasoparalysis
Venous back pressure
Hypoxia, Hypotension
Hypertension
Medical reduction of intracranial pressure
Surgical reduction of intracranial pressure
DIC
Effects of alcohol

76
/ CHAPTER 6
. If there is one distal middle cerebral artery aneurysm
and the patient is stable, excise the aneurysm. Exter-
nal carotid—internal carotid anastomosis may be re-
quired as an adjunct.
If there is a proximal or unruptured aneurysm or an
aneurysm on a critical branch, treat the patient with
antibiotics and obtain serial angiograms to see if the
aneurysm is resolving, stable, or enlarging. Consider
excising enlarging aneurysms, and follow healing an-
eurysms until they disappear. (The appropriate fre-
quency for angiograms is not well established.)
Irrdividualize if there are multiple aneurysms.
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CHAPTER /
Principles 0fNeiir0snrgery,
edited by Robert G. Grossman. Rosenber © 1991.
Published by Raven Press, Ltd., New Yor .
Cerebrovascular Occlusive Disease
James E. Rose
Historical Review, 79
The Natural History of Cerebrovascular Disease, 80
Prognosis and Natural History of Transient Ischemic
Attacks, 80
Natural History of Cerebral Infarction, 81
Pathology and Pathogenesis, 82
Symptoms and Signs, 82
Neurologic Examination, 83
Clinical History, 83
A Clinical Examination, 83
Cardiac Evaluation, 84
Neuroradiology, 85
Carotid Endarterectomy, 88
Indications, 88
The Asymptomatic Carotid Bruit, 89
Anesthesia and Patient Positioning, 90
Stroke secondary to occlusive disease is the third leading
cause of death in the United States, responsible for more
than 200,000 deaths a year. It is the second leading cause
of cardiovascular death in the United States, with an
annual incidence of approximately 160 per 100,000 pop-
ulation. In addition, stroke must be considered one of
the most devastating diseases; it can change an intelli-
gent, talented human being into a paralyzed, nonco1n—
municative individual. It is not only a socioeconomic
drain on our country but also a disruptive and burden-
some force that must be dealt with by the patient's fam-
ily. C. Miller Fisher has succinctly denned the victim of a
debilitating stroke as an "individual in the state of super-
death" (1).
HISTORICAL REVIEW
Occlusion of the major cerebral aiteries has been con-
sidered for centuries. In 1684, Sir Thomas Willis de-
scribed this phenomenon, and Abercromby in 1828
J. E. Rose: DepaitmentofNeurologicalSurge1y, Baylor Col-
lege of Medicine, Houston, Texas 77030.
79
Incision and Dissection, 90
Endarterectomy, 91
Vein Patch, 91
Cerebral Protection, 95
Postoperative Monitoring, 97
Complications, 97
Results,99
Extracranial-Intracranial Bypass Surgery, 101
Indications. 101
Surgical Technique. 102
Postoperative Blood Flow. 103
Case Example. 107
Saphenous Vein Bypass Graft, 107
Extracranial-Intracranial Bypass Surgery—Results in
the Treatment of Occlusive Vascular Disease, 108
References, 109
compared cerebral infarction to limb gangrene when
there was interruption of blood supply (2). In 1844,
Todd reported patients with a stroke—like picture second-
ary to dissecting aneurysms of the innominate artery (3).
Savory, in 1856, recorded occlusive disease affecting the
aortic arch (4); the clinical features of this pathologic
process were further elucidated by Broadbent (5). In
1905, Chiari described cerebral emboli, which he felt
originated from atherosclerotic plaques in the carotid bi-
furcation (6). Egas Moniz's contribution of cerebral angi-
ography made it possible to diagnose clinically the pre-
cise anatomical sites of occlusive vascular disease (7). C.
Miller Fisher described the basic pathologic process in
the carotid artery as aiteriosclerosis and described neuro-
logic syndromes associated with these pathologic lesions
(8,9). The first successful surgical reconstruction of the
carotid artery in the neck was performed by Cairea, Mo-
lins, and Murphy in 1951 (10). In 1953, Strully et al.
reported an attempted thrombectomy of the internal ca-
rotid aitery; however, they were unable to reestablish
ﬂow (11). In 1954, Eastcott et al. performed a section of
the carotid bifurcation in a patient with transient ische—
mic attacks, successfully restoring ﬂow by an end—to—end

80 / CHAPTER7
anastornosis between the common carotid and the inter-
nal carotid artery (12). DeBakey et al. reported recon-
struction of the left internal carotid artery in August of
1953 (13). In 1954, Denrnan et al. removed an occluded
left carotid bifurcation and replaced the resected seg-
ment with a preserved homograft (14). In 1956, Cooley
performed a carotid endarterectomy in a patient with a
cranial bruit who had carotid stenosis (15). Local hyper-
thermia using crushed ice was used for cerebral protec-
tion, and a horizontal rather than a hnear arteriolomy
was utilized for the endarterectomy.
The prophesies of C. Miller Fisher that "it is conceiv-
able that sorne day vascular surgery will find a way to
bypass the occluding portion of the artery during the
period of ominous bleeding symptoms" and that "anas—
tornosis of the external carotid artery or one of its
branches with the internal carotid artery above the area
of narrowing should be feasible" were soon to be realized
(9). As reconstructive vascular surgery was applied to the
larger vessels, it was obvious that there was a need for
bypassing the occluded segments of the heretofore "inac—
cessible" segments of disease in smaller vessels. Al-
though Carell and Gouthrie in 1912 had done much
work in the field of s1nall—vessel suturing technique, it
was not until the operating microscope was introduced
into surgery that the smaller vessels such as the superﬁ-
cial temporal artery and middle cerebral artery could be
anastomosed (2). Such pioneers as Jacobson and Suarez
in 1960 and Buncke and Schultz in 1965 further refined
the techniques of microvascular surgery (2). In 1967,
Donaghy and Yasargil performed the first superficial
temporal artery—middle cerebral artery anastomoses
(2,16). Since that time, the total of extracranial—intracra—
nial anastomoses performed around the world has proba-
bly exceeded 15,000 to 20,000 (2). Despite the initial
optimism for this seemingly rational concept, enthusi-
asm has waned, owing to the recent results of the rnulti—
center, double—blind randomized clinical trial of the ex-
tracranial—intracranial artery bypass surgical procedure
(17). In a period of follow—up ranging up to five years, no
significant difference in outcome was found between the
medically and surgically treated groups. Although much
criticism of this study has been raised, the large rnulti—
centered, randomized prospective clinical trial method
of evaluating the efficacy of cerebrovascular procedures
has many merits. At present, several other multicentered
trials evaluating the efficacy of carotid endarterectomy
for the treatment of transient ischemic attacks and pre-
vention of stroke are currently in progress (18,19, J.
Grotta, personal communication 1989).
THE NATURAL HISTORY
OF CEREBROVASCULAR DISEASE
It is important to know the incidence and natural his-
tory of both transient ischemic attacks and completed
cerebral infarction in order to determine the potential
benefits and risks of the therapeutic modalities to be con-
sidered. One rnust consider not only the risk of the sur-
gery or the medical regime itself but also the risk of leav-
ing the disease untreated. Also to be considered are the
risks of investigative procedures, including angiography,
as well as the long—term benefits of an operation.
I will use, for the remainder of this discussion, the
definition of stroke syndromes outlined by the Ad Hoc
Advisory Committee for the classiﬁcation of cerebrovas-
cular disease (20):
1. Transient ischemic attack (TIA) is a temporary and
focal episode of neurologic dysfunction of presumed
vascular origin, lasting typically 2 to 15 minutes, but
occasionally as long as 24 hours. The episode clears
without residual neurological deficits. It may be clas-
siﬁed as either vertebrobasilar or carotid, depending
on the vascular territory of the presumed ischemia.
Arnaurosis fugax is included as part of the definition
of carotid transient ischemic attack (21).
2. Prolonged reversible ischemic neurological deﬁcit
(PRIND or RIND) at first appears to be an ischemic
stroke. However, the neurologic deficit usually sub-
sides completely within two to seven days. This attack
is not classified as a transient ischemic attack because
of its duration. However, it differs from a completed
stroke as it is reversible (22).
3. Stroke in evolution is a clinical syndrome consisting
of neurologic deficits that become progressively worse
within 6 to 48 hours. It generally progresses in a step-
wise fashion rather than continuously, and probably
represents a continuing process involving spreading
infarction, edema, and occasionally hemorrhage.
4. Complete stroke may or may not be preceded by a
transient ischemic attack and usually develops rap-
idly. The neurological deficits are usually quite se-
vere, and arc, in general, irreversible (22).
Prognosis and Natural History
of Transient Ischemic Attacks
Patients who have transient ischemic attacks are defi-
nitely stroke prone. Studies that illustrate the incidence
of infarction among untreated patients with transient
ischemic attacks are shown in Table 1. Ofthose patients
with transient ischemic attacks who do not die of non-
stroke—related illness, about one—third will have a stroke
within five years of their first attack (23,24). Further-
more, in those patients with transient ischemic attacks
who undergo cerebral infarction, one—fifth will have had
their stroke within one month following their initial
TIA, and approximately one—half of them will have had a
stroke within a year after their first TIA (Fig. 1). After the
first six months following a TIA, the occurrence of stroke
is approximately five to eight percent at each year of

follow—up (25,26). Toole estimated the chance of devel-
oping a cerebral infarction within five years of a TLA at
approximately 30 percent (27). The risk of subsequent
stroke increases with age. appears to be slightly greater in
women than men, and appears to be slightly less in the
Vertebrobasilar than in the carotid territory; the number
of attacks suffered by individuals is highly variable (28).
The accuracy in predicting which patients with transient
ischemic attacks will have a stroke is controversial. How-
ever, most agree that patients who have multiple epi-
sodes in a short period of time are at higher stroke risk
(29). There are conﬂicting views, however, that suggest
that the number and duration of transient ischemic at-
tacks are not accurate predictors of stroke risk; and in-
deed, many patients will have only a single TIA prior to
stroke (21,30). A reasonable estimate of the probability
of stroke and/or death, at least among males, may be
based on the men with threatened stroke taking a pla-
cebo in the Canadian Cooperative Study Group trial of
aspirin and sulfinpyrazone (31). The incidence of stroke
was about 10 percent each year. To complicate this pic-
ture further, the mortality and morbidity from stroke is
believed by some to have been declining steadily during
the past 25 years. Although the reasons for the decline
are not obvious, rnultifactorial aspects such as better
control of hypertension and diabetes, control of choles—/
terol and obesity, surgery, the use of antiplatelet aggrega-
tion medication, awareness ofthe heart in the pathogene-
sis of cerebral ischemia, and the decline in the use of
tobacco may all play significant roles. All of these vali-
ables make rational and scientific decisions regarding the
safest and most effective treatment of ischemic vascular
disease even more difficult.
Natural History of Cerebral Infarction
In spite of modern advances in the management of
vascular disease, stroke is still a serious and immediate
threat to life. The immediate outlook for survival de-
pends on several factors, such as age of the patient and
the type, size, and anatomic site of the cerebrovascular
TABLE 1 . Incidence of infarction among
untreated TIA patients
Fo||ow—up Infarction
Source Number (months) (°o)
Toole (1974) 56 66 13
Whisnant(1973) 198 Up to 120 36
Friedman(1969) 44 27 18
Baker (1968) 79 41 22
Acheson (1971) 151 55 62.3
Marshall (1954) 51 48 2
Goldner(1971) 140 180 37
Acheson (1964) 82 38 51
Siekert(1963) 160 36-96 36
(From ref. 148, with permission.)
CEREBROVASCULAR OCCLUSIVE DISEASE / 81
No treatment
n=130
A/C treatment
n=69
Expected
4 6 8 10
Years after first TIA
FIG. 1 . Conditional probability of occurrence of stroke after
first TIA in patients treated and untreated with anticoagu-
lants. Expected probability is for population of same age and
sex distribution and is based on stroke incidence rates for
Rochester, Minnesota, 1955 through 1969. (From ref. 143,
with permission.)
lesion. Ischemic lesions carry a more favorable prognosis
than do hemorrhagic ones (32). Most fatal ischemic le-
sions are extensive brain hemispheric infarcts with cere-
bral edema, which contrasts with the rnore favorable
prognosis in patients who have so—called lacunar strokes.
The latter term refers to various well—defined vascular
syndromes caused by small infarctions in the basal gan-
glia or the pons (33).
In most cases of fatal cerebral infarction, the cause of
death is irreversible failure of the vital functions of the
brainstem secondary to uncal herniation. To predict a
patient's chances of surviving a recent stroke, attention
is centered on neurologic signs suggesting brainstem
compromise, the most important clinical sign ofwhich is
impairment of the level of consciousness. Patients who
are fully awake and alert are unlikely to die from the
brain lesion itself; the prognosis depends upon the pres-
ence or absence of other complicating extracerebral dis-
ease, in particular, cardiac, pulmonary, or renal dis-
orders (30,34). The condition of those patients who
recover from a stroke may range from no to slight disabil-
ity, which allows self care, to severe disability, which re-
sults in being bedfast and incontinent and in requiring
nursing care. In a series of 404 survivors from stroke
described by Rankin, 15 percent made complete recover-
ies, 37 percent remained only slightly disabled, and 16
percent remained moderately disabled, meaning that
they were able to walk but needed some help with dress-
ing (35). The remaining 32 percent either became more
disabled or died within several months. Optimistically,
50 to 70 percent of the patients who survived the stroke
became able to walk unaided, whereas 20 to 30 percent
of these patients became permanently and severely hand-
icapped. Contrasted to this is a study from the Mayo
Clinic that found that, six months following cerebral in-
farction, 29 percent of patients had normal neurological

82 / CHAPTER7
function and 71 percent retained manifestations of neu-
rologic dysfunction. In this latter group, 18 percent were
still capable of self care. The incidence of recurrent
strokes in the first five years was 20 percent (36). Wal-
lace, studying the natural history of stroke patients in
Melbourne, Australia (37), found that the mortality rate
with the first recurrent stroke was 35 percent, but, with
each subsequent recurrence, the mortality rate was 65
percent. Baker et al. studied 430 patients who survived a
cerebral infarct (38). Of these, 26 percent developed a
second stroke and another 20 percent began to have new
transient ischemic attacks. Some of these had both.
Therefore, 38 percent developed a new event, either a
stroke or a transient ischemic attack (3 8).
In Marquedsen's series, the annual rate of recurrence
of stroke remained at the initial level for at least 10 years
after the stroke (34). He believed that the annual recur-
rence rate suggests that, in the absence of death from
causes other than cerebrovascular accident, 75 percent
of the patients could be expected to have a recurrent
stroke within 15 years of their original stroke. He sug-
gested that any patient who survived long enough is
likely to have a further cerebrovascular accident. It is
evident from the relatively low annual risk of recurrence
that the majority of patients die from other causes before
having another stroke. This was his explanation of why
the overall recurrence rate observed in follow—up rarely
exceeds 30 percent and why few patients actually suffer
more than two recurrences. Particularly, high recurrence
rates have been observed in patients with cerebral ernbo—
hsrn from rheumatic heart disease (32). We are, there-
fore, concemed with not only the signiﬁcance of rnorbid—
ity and mortality with the initial stroke but also the
remarkably high rate of recurrence. Many of these pa-
tients will make a signiﬁcant recovery, and, as recur-
rence is associated with a high morbidity and mortality,
every effort possible to prevent recurrences should be
made.
PATHOLOGY AND PATHOGENESIS
Subarachnoid hemorrhage and cerebral hemorrhage
account for about 20 percent of all strokes (39). Another
20 percent are caused by occlusion of the lenticulostriate
arteries resulting in infarction in the brainstem and basal
ganglia, leaving 60 percent due to occlusion of a major
brain vessel either by embolism or thrombosis (39,40).
Of these latter patients, approximately 42 percent have
underlying cardiac factors, including myocardial infarc-
tion, valvular heart disease, subacute bacterial endocar—
ditis, or atrial fibrillation, which serves as a source of
emboli. The remaining 58 percent are vascular occlu-
sive, either thrombolic or ernbohc in origin (39).
The atheromatous plaque in the extracranial arteries
can be a source of either thrombotic or platelet emboli.
Millikan in 1955 noted that transient ischemic attacks
could be treated successfully by anticoagulant therapy,
thus giving credence to the embolic therapy of cerebral
ischemia (41,42). Further evidence that atheromatous
plaques can be a source of emboli was given by Hollen—
horst, who described plaques within retinal vessels and
suggested that these were cholesterol crystals from ather-
omatous lesions (43). Additional evidence is supported
by the fact that carotid ischemic attacks may abruptly
stop when a carotid stenosis progresses to total occlusion
(44). These emboli may be the result of atheromatous
debris, platelet aggregates, or thrombi being released in
the arterial stream. The necrotic—stenotic atherosclerotic
plaque may undergo some central necrosis, with dis-
lodgernent of some of the atheromatous debris into the
arterial lumen, which further embolizes to the brain. An
ulcerated surface of the plaque may serve as a nidus for
the aggregation of platelet aggregates. These aggregates
can be dislodged into the internal carotid artery and may
also ernbohze into the intracranial circulation. The same
ulcer may serve as nidus for a thrombus formation. This
thrombus can either propagate and result in complete
occlusion of the internal carotid artery, or it may be dis-
lodged, resulting in distal embolization. Hemorrhage
may occur in the center of the necrotic plaque, resulting
in occlusion of the internal carotid artery. A similar pro-
cesscan occur in the depths of a necrotic ulcer, also re-
sulting in occlusion of the artery.
The chnical effects of cerebral embolism or thrombo-
sis depend upon the acuteness of onset, the ability of the
body to lyse the ernboh in order to restore circulation,
and the presence of adequate collaterals. In the nor-
rnothermic man, the critical ischemic threshold of cere-
bral blood ﬂow is about 20 cc per 100 gram brain per
minute. Below this level, cerebral electrical activity grad-
ually disappears. With a blood ﬂow of about 15 cc per
100 grams per minute, the evoked electrocortical re-
sponses disappear cornpletely, and, at a level of 6 cc per
100 grams per minute, there is a massive release ofpotas—
siurn from the cells.
SYMPTOMS AND SIGNS
The symptoms and signs ofcerebrovascular occlusive
disease reﬂect alteration in brain function in the particu-
lar territory supplied by the involved cerebral vessel.
Hemispheric cerebrovascular insufficiency is the result
of involvement in the carotid territory. These symptoms
usually consist of contralateral weakness of the arm or
leg; paresthesias, ifthe sensory cortex is involved; and, if
involving the dominant hemisphere, variable degrees of
dysphagia. Arnaurosis fugax, a transient, monocular
blindness, is usually of rapid onset, lasts several minutes
(but may last up to an hour), and is ipsilateral to the
lesion. Pain referred to the temporal area may be seen in

patients with high—grade occlusive disease of the carotid
artery; this pain usually worsens when the patient rises to
the erect posture. A contralateral homonomous hemian-
opsia may be present in anterior circulation ischemia.
Neurologic Examination
The neurologic examination of a patient is usually
normal if the patient has had a transient ischemic attack.
Residual neurologic deficits include hemiparesis, altered
sensation including two—point discrimination or other
parietal sensory deficits, or hyperreﬂexia. If amaurosis
fugax is associated with a high—grade carotid stenosis or
occlusion, there is usually a significant decrease in the
ophthalmic artery pressure as measured by ophthalrno—
dynarnornetry or oculoplethysmography. Vascular in-
sufficiency in the vertebrobasilar system involves syrnp—
toms of true vertigo, ataxia, diplopia, bilateral visual
changes, alternating paresis or paresthesias, drop attacks,
dysarthria, and homonomous hemianopsia. Other
symptoms such as lightheadedness, decrease in rnenta—
tion, headache, confusion, personality changes, and syn-
cope may be associated with vertebrobasilar insuffi-
ciency. However, it is difficult to ascribe these symptoms
solely to vertebrobasilar insufficiency, as they are often
associated with disturbances of the inner ear, vaso—vagal
reﬂexes, and other medical conditions. With persistent
symptoms, one may find, on neurological examination,
evidence of nystagrnus, cerebellar ataxia, facial hypalge—
sia, tongue weakness, ocular motor nerve palsies, and
pupillary abnormalities (e.g., Horner's syndrome). With
a thorough evaluation, one should be able to determine
the etiology of the presenting symptoms and signs, as
well as the anatomic location of the process, in about 80
percent of patients (47).
Clinical History
The clinician must ﬁrst decide whether or not the pa-
tient has a vascular lesion. A clue in the patient's history
that suggests this lesion is an acute onset with rapid pro-
gression to a deficit that usually plateaus. Some patients
will continue to have progression of their symptoms
while in the hospital. Other clinical entities, such as ex-
panding rnass lesions, traumatic hernatornas, and de-
rnyelinating or infectious processes may mimic stroke,
especially the "stroke in evolution."
less common but important causes of occlusive vascu-
lar disease include the collagen diseases, blood dyscra—
sias, and valvular heart disease. A family history is irn—
portant to determine if there is a history of diabetes,
hornocystinuria, hyperlipidemia, or premature vascular
disease. A thorough medical history regarding other con-
tributory rnedical conditions such as hypertension and
migraine must be obtained. Specific inquiry should be
CEREBROVASCULAR OCCLLSIVE DISEASE /83
made regarding the presence of hematotogic disorders
such as polycythemia, thrombocytosis, sd<b<d dr
ease, and thrombotic thrornbocytopeniapurpura. Acare—
ful search should be made for a history of cardiac arrhyth-
mias, rheumatic heart disease, valve replacement, or
drug abuse. Certain types of medications, especially oral
contraceptives, may play a role in the possible etiology of
the stroke syndrome. A history of exposure to radiation
may alert the physician to possible acute inﬂammatory
vascuhtis, which may occur after a latent period of 7 to
12 months. A history of weight loss may suggest carci-
noma, which may be associated with thrombotic occlu-
sions of cerebral vessels. Von Recklinghausen's disease
occasionally present with vascular symptoms and ca-
rotid angiography may show vascular dysplasia with al-
ternating segments of stenosis and dilatation (28). Care-
ful questioning should be directed toward those patients
who have traveled abroad when cerebral complications
ofrnalaria are suspected.
Clinical Examination
A careful physical examination with emphasis on the
skin and ocular fundus may detect evidence of some of
the inherited disorders of connective tissue. A careful
search of the veins in the extremities may suggest a link
between chronic drug abuse and cerebral angiopathy
(28). Examination of the oropharynx may reveal evi-
dence of trauma responsible for vessel injury. Likewise,
local inﬂammation of the retropharyngeal tissues and
lymph nodes may result in arteritis and subsequent vas-
cular occlusion.
Palpation of the scalp vessels may reveal tenderness
and nodularity suggesting giant cell arteritis. Cutaneous
evidence of ecchyrnosis or purpura may suggest a blood
dyscrasia. Examination of the conjunctivae and nail
beds may give a hint to the presence of a severe anemia,
which may be an overlooked cause of cerebral is-
chemia (47).
Cardiac ernboli as a source of stroke may be suggested
by signs of ernbohsrn in such other organs as the retina,
nails, or skin. Auscultation may reveal a murmur, sug-
gesting rheumatic valvulitis or bacterial endocarditis.
Endocarditis, especially when associated with drug
abuse, may present as an acute stroke due to the ernboli
from the infected heart valves or as a subarachnoid hem-
orrhage frorn ruptured mycotic aneurysms. Marantic
endocarditis is seen most commonly as a terminal event
in advanced malignant disease and usually involves carci-
noma of the pancreas and stomach. It is thought that
mucus or some other product of tumor cells is released
into the circulation, where it acts as a tissue thrornbo—
plastin initiating intravascular coagulation (28). Cardiac
myxoma is a special condition that deserves our atten-
tion because of the possibility of cure. Although a rare

84 / CHAPTER7
condition, this tumor, which is usually in the left atrium,
may cause ﬂuctuating murmurs, rhythm changes, heart
failure, and cerebral ernboli. Constitutional effects in-
clude fever, anemia, increased sedimentation rate, and
hyperglobulinemia. Echocardiography is useful as a
diagnostic test.
The peripheral vascular examination is one part of the
total evaluation of the patient with vascular disease. Re-
cordings ofblood pressure both supine and standing and
in both arms and legs are essential. One may diagnose
postural hypotension by this maneuver; ophthalmody—
namometry performed simultaneously may detect evi-
dence of cerebral orthostatic hypotension in patients
who do not have significant systemic blood pressure
changes (48). A generalized vascular examination in-
cludes palpation of radial, brachial, popliteal, tibial, and
dorsahs pedis pulses. Examination of the skin for evi-
dence of ischemic changes is important, as is the pres-
ence of a bruit in the neck, abdomen, or groin.
The physician must listen for bruits over the carotid,
subclavian, brachial, aortic, and groin areas. A bruit is
abnormal and its presence suggests turbulence and arte-
rial disease (49). The classical bruit of carotid artery dis-
ease is rnidsystolic and rather high—pitched, radiates
through the angle of the jaw, and is a sign of significant
stenosis (21). When a carotid bruit changes with time or
disappears, it is associated with a "thrombotically active
laque" and is believed to be an ominous sign of impend-
mg carotid occlusion (50).
Other aids include careful neuro—ophthalmologic ex-
amination to detect subtle field changes and pupillary
abnormalities. A funduscopic examination may reveal
the presence of such systemic disease as diabetes, hyper-
tension, and generalized arteriosclerosis. The fundu-
scopic examination may also reveal evidence of choles-
terol and platelet emboli—the so—called Hollenhorst
plaques (43). The retina may show dark angioid streaks
radiating from the disk, with pigmentary changes and
hemorrhagic lesions at the macula suggestive of
pseudoxanthoma elasticum. One particular ophthalmo-
logic finding, venous stasis retinopathy, resembles dia-
betic retinopathy and consists of rnicroaneurysrn for1na—
tion, retinal hemorrhages, neovascularization, and
occasionally glaucoma. This should be recognized as a
correlate of occlusive disease of the carotid artery sys-
tem (51).
Ophthalmodynarnornetry (ODN) is a bedside test that
may be employed with safety and is useful in examining
patients who have signiﬁcant occlusive vascular disease
of the carotid system. Normal retinal artery pressure is
approximately one—half to two—thirds of the brachial
pressure, and a difference of over 15 percent between the
pressures on the two sides suggests occlusive disease of
the carotid system (52).
Ultrasonic Doppler imaging detects moving blood
particles in order to outline the vessel lumen. When ul-
trasound strikes a moving target of red cells, the fre-
quency of the echo will shift in proportion to that co1npo—
nent of ﬂow velocity that is parallel to the beam.
Therefore, the Doppler ultrasound instrument registers
the difference between the transmitted and the reﬂected
signal. An imaging device records the moving blood and
constructs a profile of the lumen. B—scan imaging devices
or real—ti1ne scanning provide images of the pulsating
bifurcation in transverse and longitudinal sections, out-
lining the vessel wall in real time so that the vessel is seen
pulsating. However, some lesions lie in the distal portion
of the carotid or in the petrous bone, where they cannot
adequately be visualized, and ulceration and plaques are
not always identified reliably.
Other noninvasive tests include bruit auscultation and
analysis, which are simply ways to display the intensity
of a bruit throughout the cardiac cycle as a function of
time. Turbulence sufficient to cause a detectable bruit
occurs when the residual lumen is about 2.5 to 3 mm.
The bruit is no longer audible if the residual lumen falls
below 0.5 to 0.8 mm (53). In a recent study by Castaldo
et al., a combination of ocular pneumoplethysmography
and duplex ultrasound (which uses high resolution B-
rnode imaging plus spectral analysis) was used to evalu-
ate 289 consecutive patients prior to biplane cerebral an-
giography (54). The noninvasive tests predicted the
presence or absence of hemodynamically signiﬁcant se-
vere carotid stenosis (75 percent or greater reduction in
cross—sectional area) with an accuracy of 96.2 percent. Of
538 arteries studied, 0.74 percent with angiographically
severe lesions were not detected by these noninvasive
tests. Mohr et al. performed noninvasive tests on 303
atients (40). Ninety ercent of these patients were fol-
owed for five years. troke occurred in 13.5 percent of
these patients. There was a significant correlation be-
tween the incidence of stroke and the severity of disease.
Hernodynarnically significant lesions did indicate a
group ofpatients who were at risk of stroke regardless of
their initial clinical presentation. Also, the absence of
hemodynamically signiﬁcant lesions in patients without
symptoms or in patients without true "lateralizing"
symptoms was a favorable prognostic indicator. The au-
thors also concluded that, in patients without symptoms,
the appearance of hemodynamically significant stenosis
was associated with a higher degree of stroke than those
patients without significant stenosis. The risk of death
from cardiac causes was double in patients with greater
than 50 percent stenosis.
Cardiac Evaluation
Cardiac arrhythmias as a cause of transient ischemic
attacks were once believed to be rare and to be usually

associated with a generalized cerebral dysfunction rather
than focal ischemia (55). The awareness of the heart as
an important aspect of the pathogenesis of stroke has
increased, however. As a result of improved cardiac
imaging and monitoring, 15 to 25 percent of hospital-
ized patients with ischemic events have hearts as the
source of thromboembolism (56). Patients who have
TIAs or stroke are at equal risk in the following years for
fatal and nonfatal myocardial infarction (57). A 24-hour
Holter monitor may be used in conjunction with sirnulta—
neous automatic blood pressure recordings taken every 7
to 10 seconds. In this way, one can see if transient runs of
cardiac arrhythmias actually alter the cardiovascular dy-
namics.
Neuroradiology
Computerized Axial Tomography
Computerized axial tomography (CT) is capable of
demonstrating 100 percent of intracerebral hemorrhages
(58). In addition, brain tumors, arteriovenous rnalfor—
mations, and other space—occupying lesions that can
mimic transient ischemic attacks and vascular disease
can be identified. In cerebral infarction, a CT scan
should be done as soon as possible to rule out other
sources of pathology. If the stroke is due to cerebral
thrombosis or embolism, there may be no abnormalities
in the first 36 to 48 hours. If a CT scan is repeated in two
to three days, one may see abnormalities, especially after
intravenous contrast enhancement. If no abnormalities
are seen on the CT scan, the patient's prognosis is irn—
proved (59). Infarcts that do not image on computerized
tomography are usually less than 1 cm in diameter. How-
ever, one may be able to demonstrate these lesions in 10
to 15 days after the ictus by rapid injection of iodinated
contrast medium (300 cc of 30 percent solution) (58).
The area of infarction exhibits a loss of the blood—brain
barrier, and contrast material extravasates into the ab-
normal area, producing an area of increased density. In
three—quarters of patients, the area of decreased density
in the area of infarction is due to an increase in the
amount of water in the tissues. Within the next 7 to 14
days, the borders of the infarct become more clearly de-
lineated, with decreased attenuation. Within three to
four weeks, the infarcted area becomes sharply circurn—
scribed and the degree of radiolucency plateaus, ap-
proaching the density of cerebrospinal ﬂuid (58).
Brain Scan
The technetium 99m brain scan usually reveals abnor-
malities in the area of a damaged brain within two to six
days after the onset of symptoms. In cases of hemor-
CEREBROVASCULAR OCCLUSIVE DISEASE / 85
rhagic infarction, this may occur earlier. The uptake of
the isotope by the damaged area increases for two to
three weeks and then gradually decreases over a period of
two to three months. After three months, the radionu-
clide brain scan may revert to normal. This typical evo-
lution of an infarct due to occlusive vascular disease
helps differentiate infarction from neoplasm. The tech-
nique of dynamic brain scanning using rapid camera
imaging following the intravenous injection of techne-
tium 99m is useful in demonstrating asymmetry of the
brain circulation. A late arrival time on one side is often
seen with obstruction of the extracranial—intracranial ca-
rotid artery. The early appearance of isotope on one side
of the brain, with the greatest concentration appearing
several seconds later on the opposite side, indicates de-
layed circulation to the latter hemisphere and is referred
to as the "ﬂip—ﬂop" pattern. In transient ischemic at-
tacks, one may see an abnormal dynamic brain scan
with a normal static scan, suggesting ﬂow alteration
without tissue destruction.
Cerebral Blood Flow
The use of cerebral blood flow studies utilizing diffuse
inert radioactive materials to diagnose cerebral occlusive
disease has. for the most part, been used in the research
setting. The intracarotid injection of xenon 133 has been
the most widely used technique. Intravenous xenon 133,
xenon 133 inhalation, and stable xenon inhalation blood
ﬂow using CT imaging have also been used (60). The
preservation or loss of autoregulation and cerebral vaso-
motor responses to hypocapnia and hypercapnia can be
assessed, and quantitative changes in cerebral blood ﬂow
can be determined, in order to evaluate the pharmaco-
logic and surgical procedures used to improve cerebral
blood ﬂow. Using the intravenous xenon 133 technique,
Yonekura et al. demonstrated that in patients with syrnp—
tomatic unilateral lesions (internal carotid occlusion,
common carotid stenosis, and middle cerebral artery ste-
nosis), there was a significant reduction in hemispheric
regional cerebral blood ﬂow on the side ofthe lesion (61).
In those patients who had focal transient ischemic at-
tacks only, there was a significant reduction in cerebral
blood ﬂow in the area corresponding to their symptoms,
whereas patients with unilateral lesions who did not have
focal transient ischemic attacks did not have regional
depression of cerebral blood ﬂow. The use of noninva-
sive cerebral blood ﬂow measurements may further as-
sist clinicians in selecting patients with vascular occlu-
sive symptoms likely to benefit from cerebral vascular
augmentation procedures. Whereas the technical feasibil-
ity of such surgery is well established, indications for sur-
gery, selection of patients, and duration of benefit, as
well as reproducible methods of measurement of hemo-
dynamic changes, have yet to be clearly deﬁned.

86 / CHAPTER 7
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) yields images of
the hydrogen, sodium, and phosphorus ions; however, at
"this time, clinical evaluations are limited to hydrogen
ions. In a recent series by Houser et al., 50 patients with a
clinical diagnosis of cerebral infarction were examined
with MRI and CT (62). The authors compared their re-
sults to a previous study in which 20 percent of all pa-
tients had lesions detected by CT in the basal ganglion,
brainstem, or cerebellum, whereas 40 percent of the pa-
tients had lesions detected on the MRI scanning. In the
study by Houser et al., the MRI scans were positive in 80
percent, negative in 14 percent, and undetermined in 6
percent. When a comparable CT scan was done during
the same time period, the CT scan was positive in 75
percent of patients with positive MRI scans. MRI scans,
therefore, detected every lesion shown by the CT but also
showed lesions to a better advantage in 20 percent of the
patients. Unfortunately, if the brainstem was involved,
only 60 percent of the lesions were detected clinically by
the MRI scanning. The spin echo pulse sequences
showed a positive signal, which is believed to represent
brain edema in the distribution of the infarct; it was felt
by these workers that edema within the white matter was
better shown than that in the gray matter.
Cerebral Angiography
Cerebral angiography remains the diagnostic proce-
dure of choice in patients with signs and symptoms of
Vascular occlusive disease. After CT scanning has ruled
out other lesions that mimic cerebrovascular occlusive
disease, cerebral angiography is required to demonstrate
the location of the responsible lesions and the extent of
the arteriosclerotic narrowing of the vessel lumen. Ste-
notic plaques are usually located at the origin of the arter-
ies or at their bifurcations. Most investigators agree that
65 to 70 percent obstruction of the lumen is required
before these lesions are hemodynamically significant
(Fig. 2). Ulceration of atheromatous plaques can be accu-
rately Visualized. The significance of these lesions is as a
source of emboli rather than as a cause of signiﬁcant ﬂow
alterations (Fig. 3). Intraluminal thrombosis can be de-
tected by angiography and may serve as a source of prop-
agation of either (1) even larger thrombi or (2) ernboh to
the distal arterial tree, resulting in a stroke. These lesions
are seen on angiograms as lucent, intralurninal—filling
defects and are usually associated with an ulceration or
significant carotid stenosis. Occlusion of vessels may be
identified by appropriate angiography. It is necessary to
demonstrate not only the site of the occlusion but the
possible second occlusion more distal in the arterial tree
(the so—called tandem lesion), and the caliber of other
vessels that may be used as potential donor vessels for
cerebral revascularization. Angiography provides data
=on the direction and velocity of the blood ﬂow, and the
adequacy of the collateral circulation, so that more accu-
rate indications for surgery of the supplying cerebral ves-
sels can be established.
Approximately 31 percent of the patients with syrnp—
tomatic cerebral ischemia undergoing cerebral angiogra-
phy have significant occlusive disease, in which there is a
50 percent or greater reduction in the diameter of the
lumen, representing a 75 percent reduction in the cross-
sectional area (63). The sites of arterial narrowing and
occlusions found on four—vessel angiography in patients
with transient ischemic attacks are shown in Figure 4.
About 33 percent of these lesions are considered to be
inaccessible to peripheral vascular surgical removal. In
addition, 29 percent of these patients who had surgically
accessible lesions had their problems compounded by
significant inaccessible lesions, accessibility being de-
fined as a lesion in the carotid system that can be ap-
proached frorn a neck incision. Pessin et al. analyzed 95
consecutive hospital patients with transient ischemic at-
tacks who subsequently underwent angiography (64).
While tight stenosis or occlusion was found in 52 percent
of these patients, 3.6 percent showed intracranial branch
occlusions, most without noticeable stenosis. Only two
TIA features correlated with the angiogram: TIAs greater
than one hour revealed no noticeable stenosis, and sepa-
rate hemispheric and ocular attacks in the same patient
FIG. 2. Angiogram showing a high—grade stenosis of the ICA
distal to the bifurcation. At surgery there was a tight stenosis
of the lumen, with a soft thrombus extending up another centi-
meter. The patient has remained free of symptoms following
endarterectomy.

FIG. 3. Angiogram showing the presence of a high—grade ste-
nosis with irregularities of the lumen, which includes a narrow
deep ulceration. At surgery the ulcer was the site of adher-
ence of a friable platelet—fibrin clot, which was thought to be
the source of the patients TlAs.
correlated with a tight (equal or less than 2.5 mm lumen)
stenosis. They concluded that the clinical features of
TIAs are not accurate predictors of the degree of carotid
artery disease (64).
Technique
Transfernoral cerebral angiography is preferred, as all
the cerebral vessels can be studied selectively with a sin-
gle puncture. The femoral artery is usually large and ac-
cessible so that this technique results in fewer cornplica—
tions than alternative methods (65).
Catheter angiography has the advantage of allowing
visualization of the brachiocephalic arteries from their
origin and facilitates patient positioning from multiple
projections. The basic examination includes the bra-
chiocephalic; right posterior oblique projection, includ-
ing the top of the aortic arch; and selected bilateral ca-
rotid angiography including AP and lateral views of the
neck and head, with views of the carotid bifurcation.
Selective vertebral angiography, with emphasis on the
dominant vertebral injection, is performed if indicated.
It is important to visualize each vessel in at least two
projections to avoid overlooking pathology. If vertebral
basilar insufficiency is suggested by an indication that
excessive head movement is a precipitating factor in the
pathogenesis of the symptoms, the contrast should be
CEREBROVASCULAR OCCLUSIVE DISEASE / 87
inaccessible
or Intracramal
33%
Carotid Bifurcation
38%
Vertebral origin
20%
Arch
9%
FIG. 4. Location and incidence of significant atherosclerotic
lesions. The length of the dark area at each location (mea-
sured against the scale at left) corresponds to the number of
lesions detected by arteriography in this series. (From ref.
1 44,with permission.)
delivered through the catheter while the patient's head is
both in the neutral and in the extreme lateral rotation
positions in order to detect the site of obstruction of the
vertebral artery.
One point of emphasis regarding technique involves
those patients who have suspected internal carotid artery
occlusion. The catheter is placed close to the bifurcation
near the orifice of the external carotid artery. Contrast
material is delivered at 4 oc per second for four seconds
for a total of 16 cc, as compared to the usual injection of
8 to 11 cc per second for one second. This modification
affords the advantage of better visualization of the exter-
nal carotid artery and the extent of its intracranial con-
nections, as well as producing less reﬂux of contrast back
into the common carotid artery. In this way, antero grade
ﬂow in the severely obstructed yet incompletely oc-
cluded internal carotid artery may be seen (66). Occa-
sionally, one may be able to demonstrate the dilated ex-
ternal carotid artery filling the internal carotid artery via
ophthalmic collaterals. The cervical internal carotid ar-
tery may be faintly seen by this method, revealing the
so—called "slim sign" (66) (Figs. 5, 6, and 7).
Complications
With the transfemoral technique, the minor cornpli—
cation rate is approximately 3 percent and consists of
transient neurological deficits in 1 percent of these pa-
tients, local hematomas in 1 percent, and an intramural
or subintimal injection in about 0.3 percent (65) (Fig. 8).
Major complications of transfemoral cerebral angiogra-
phy range from 0.2 to 1.5 percent with an average of

88 / CHAPTER 7
FIG. 5. Arch aortogram shows nonfilling of the right ICA.
about 0.5 percent of these patients. Major complications
include femoral thrombosis (0.1 percent), stroke (0.2
percent), and death (0.5 percent). The complication rate
FIG. 6. Selective common carotid inaction of contrast at4
cc/sec for 4 seconds delivers Urgei volume ot contrast. This
demonstrates retrograde filling of the ICA from ophthalmic
collaterals, with a string—like, opacification of the internal ca-
rotid artery into the cervical region (arrows).
FIG. 7. The same patient after cervical carotid endarterec-
tomy. This figure shows good visualization of the internal ca-
rotid artery (arrows) and filling of the intracranial vessels.
in the patient with cerebrovascular disease is approxi-
mately four times that in patients without cerebral is-
chemic lesions (65). Children under 10 years old have
approximately twice the number of complications of
those over 10 (67). Neurologic complications are usually
related to preexisting cerebrovascular disease and are
rare in its absence.
CAROTID ENDARTERECTOMY
Indications
In patients who have a high—grade stenosis of the inter-
nal carotid aitery, endaiterectomy restores normal ﬂow
through the carotid system, and removes the source of
emboli. The clinical syndromes to which carotid endar—
terectoiny may be applied are transient ischemic attacks,
small infarcts with mild residual neurological deﬁcits,
the asymptomatic carotid bruit, and an acute neurologi-
cal deficit that is progressing or ﬂuctuating. The clinical
findings must be correlated with such angiographic ab-
normalities as carotid ulceration, carotid stenosis, ca-
rotid occlusion, bilateral carotid stenosis or ulceration,
or ipsilateral carotid stenosis with contralateral occlu-
sion.
In general, carotid endaiterectomy is not reco1n—
mended for the patient with a large completed infarc-
tion, as there is increased risk of postoperative intrace-

CEREBROVASCULAR OCCLUSIVE DISEASE
Transient Neurologic Deficit 1 % (0-1.25%)
Minor 3%
(0-11%)
Local Hematoma 1 % (0-1.8%)
Intramural or Subinﬁmal lnjecﬁon 0.3% (0-1.6%)
Transfemoral
Major 0.5%
(0-1 .5%)
Femoral Thrombosis 0. 1 % (0-0.3%) -
Loss of U1
0.01 % (0-0.06%)
Stroke 0.2% (0-0.3%)
Death o.o5% (o-0.1%)
FIG. 8. Complications of cerebral angiography. (From ref. 145, with permission.)
rebral hemorrhage and lack of recovery after restoration
of the ﬂow (68). The primary indication for carotid end-
arterectorny is transient ischemic attacks associated with
internal carotid stenosis or significant ulcerative disease.
Endarterectorny is also indicated in patients with arnau—
rosis fugax, persistent neurological deﬁcits, and continu-
ing TIAs in the presence of carotid stenosis or ulceration.
In those patients with carotid stenosis or occlusion with
stepwise progression of the neurological deﬁcits, treat-
ment is controversial. However, there is an increasing
body of evidence which suggests that early angiography
and surgery in these patients will restore blood ﬂow
and prevent permanent neurologic dysfunction (40,
69,70,7l).
The Asymptomatic Carotid Bruit
The question ofhow to manage the asymptomatic ca-
rotid bruit is still not solved. There have been several
series of patients with asymptomatic carotid bruits who
have been followed but upon whom no surgery was per-
formed. These results are shown in Table 2 (72-75).
These data suggest that the asymptomatic bruit asso-
ciated with signiﬁcant (i.e., equal or greater than 50 per-
cent) stenosis is associated with a significant incidence of
ischemic symptoms. The question is whether or not sur-
gery can alter this natural history. Current data suggest
that surgery should be restricted to those patients with
hemodynamically signiﬁcant lesions who have no other
signiﬁcant cardiac or other risk factors (75). During a
long—terrn study of up to 16 years by Thompson, the
incidence of subsequent stroke was 4.6 percent in oper-
ated patients and 17.4 percent in a comparable group of
nonoperated, asymptomatic patients (75). The inci-
dence of later transient ischemic attacks in the surgical
group was 4.5 percent compared with 26.8 percent in the
control group (75). We feel that any bruit that is harsh,
high—pitched, and unilateral should be followed closely.
Ifit is believed that the lesion has hemodynamic signifi-
cance, angiography is recommended, and, if signiﬁcant
stenosis is diagnosed, surgery is recommended. Failure
to achieve surgical results with less than a I percent mor-
bidity/mortality should deter one from performing ca-
rotid surgery.
Antiplatelet agents (e.g., aspirin) have been widely
used in patients with occlusive vascular disease. We are
not aware of any study that has clearly shown significant
beneﬁt from aspirin for stroke prevention. In the Cana-
dian study, the incidence of stroke in males was the same
in the aspirin—treated groups as in the control group (31).
In fact, in women the incidence of stroke was higher in
the aspirin—treated group than the control group (32). It
is this author's opinion that the surgical procedure—if
done with a very low rnortality/rnorbidity—can help
prevent strokes in the appropriately chosen patient. Un-
til a definitive randomized prospective study is done that
clearly answers the question of whether a particular
group ofpatients with vascular occlusive disease unques-
tionably beneﬁts from surgery, we must individualize
each patient and treat each according to the available
data at hand.
TABLE 2. Long—term follow—up ofpatients with asymptomatic bruits: No surgery
Period of % Incidence of ischemic:
Group % Stenosis follow-up symptoms and/or stroke
1 Roedever et al. (72) 80 12 months 46
Moore et al. (72a) 50 5 years 21
Barnes et al. (73) 50 31 months 32.8
Baird et al. (74) 75 3 years 50
Thompson (75) 50 1 6 years 44

90 / CHAPTER?
Anesthesia and Patient Positioning
General endotracheal anesthesia is used in carotid end-
arterectomy to provide a good airway and to maintain
high oxygen concentration and normocarbia. Hypercar—
bia may increase cerebral blood ﬂow to normal tissue at
the expense of the damaged area, producing an intrace-
rebral steal. Likewise, induced hypocarbia may reduce
cerebral blood ﬂow, theoretically rendering the brain
more susceptible to ischemia (77,78). When the patient
arrives in the operating room, a central venous line is
placed, as well as a large peripheral IV. A vasopressor IV
drip using Neo—Synephrine is prepared, as well as a vaso-
dilator drip of sodium nitroprusside to be used to rnain—
tain a stable blood pressure. An intra—arterial radial ar-
tery catheter is inserted for constant monitoring of the
systemic arterial pressure. Electroencephalogram elec-
trodes are attached to the scalp. An indwelling Foley
catheter is inserted after the patient has been anesthe-
tized. Anesthesia is induced slowly, with particular at-
tention given to maintaining adequate cerebral perfu-
sion pressure. All attempts are made to avoid precipitous
rises or drops in the arterial pressure, which may result in
cerebral ischemia. We prefer a narcotic and muscle re-
laxant—nitrous oxide—oxygen technique in order to rnain—
tain an EEG tracing that is not slowed by deep anesthe-
sia. The patient is placed in the supine position with the
head elevated enough to ensure good drainage into the
superior vena cava from the cervical veins, in order to
minimize bleeding. The head is extended slightly, using a
small thyroid bag beneath the shoulders, and is rotated
away from the operative side. The operating table may
be tilted slightly to prevent extreme head rotation and
extension. Extreme head turning may result in
decreased blood ﬂow through the opposite carotid
artery (79).
Incision and Dissection
Optical loupe magnification and a ﬁber—optics head-
light are essential for optimal visualization of structures.
The incision is marked on a line extending from the tip
of the mastoid process, running anterior medially and
parallel to the anterior border of the sternocleidornastoid
muscle, to the lower neck. The incision is canied sharply
through the skin and the platysrna muscle. Dissection is
carried along the anterior border of the stemocleidornas—
toid in an avascular plane. The greater auricular nerve,
which crosses the upper portion of the stemocleidornas—
toid, may be divided if necessaiy. However, all attempts
should be made to preserve this nerve, as cutting the
nerve can cause a numb and uncomfortable ear. The
common facial vein, which serves as a landmark for the
carotid bifurcation, is dissected and doubly ligated. A
segment of this vein or branch of the external jugular
vein may be used as a source of a vein patch if angio-
plasty is required. The sternocleidornastoid muscle is
dissected along its anterior border until the common ca-
rotid artery is encountered. At this point, two self—retain—
ing retractors are used to maintain exposure.
The dissection proceeds posteriorly until the lateral
aspect of the internal jugular vein is identified. Dissec-
tion then continues along the medial aspect of the inter-
nal jugular vein. Utilizing the assistant to pick up the
tissue away from the carotid, just opposite the surgeon, is
a valuable technique in maintaining this plane of dissec-
tion. Using sharp dissection with Metzenbaurn scissors,
one develops an avascular plane between the carotid ar-
tery medially and the internal jugular vein laterally. In
the case of an extremely high carotid bifurcation, it may
be necessary to extend the incision beneath the angle of
the j aw posteriorly to the mastoid process. Rarely, it may
be necessary to divide the posterior belly of the digastric
muscle. Care must be taken to avoid injury to the hypo-
glossal nerve (which, in most cases, is just rostral to the
carotid bifurcation) as it passes anteriorly to innervate
the tongue.
The internal jugular vein is retracted laterally to ex-
pose the common carotid artery. The vagus nerve is
usually located posteriorly in the carotid sheath, and care
must be taken to avoid damage to this structure. During
dissection of the common carotid artery, the surgeon
must use minimal manipulation of this vessel. The tissue
around the artery is gently lifted so that the surrounding
tissue is dissected away from the artery. The adventitial
tissue is incised to gain access to the periarterial plane of
Leriche. The common carotid artery is then mobilized
circurnferentially and a moist umbilical tape is placed
around this structure, proximal to the diseased plaque.
The area of the common carotid so selected should be
free of atherosclerosis. Once again, the artery should be
minimally manipulated to prevent ernbolization that
may occur from dislodgernent of intramural debris in
the diseased segment of the vessel. The exposure is
carried distally along the posterior—lateral aspect of the
common carotid artery to the carotid bifurcation. At this
point, the carotid sinus is blocked with 1 percent lido—
caine hydrochloride to prevent the carotid sinus reﬂex of
bradycardia and hypotension. The distal internal carotid
is then dissected circurnferentially until the normal in-
ternal carotid artery is visualized.
Dissection of the external carotid artery is accorn—
plished next. A rather constant branch, the superior thy-
roid artery, is dissected for a short distance, and a 2-0 silk
suture is placed around this artery and anchored with a
hemostat. Further exposure of the bifurcation may be
obtained by dividing the tissues between the internal and
external arteries. These tissues act as a point of attach-
ment that anchors the bifurcation to surrounding struc-
tures. After division of these tissues, the bifurcation may

settle caudally, allowing the surgeon to gain additional
exposure of the internal carotid artery,
Endarterectorny
The hypoglossal nerve is identified as it crosses the
bifurcation. Additional mobilization of the hypoglossal
nerve will allow further exposure and mobilization of the
internal carotid artery. When hemostasis has been ob-
tained, the patient is given an intravenous dose of hepa-
rin (usually 100 units per kg ofbody weight). Blood pres-
sure is elevated to levels slightly above the resting
pressure, usually to 150 to 177 mm of mercury systolic
pressure (unless contraindicated by cardiac status), using
phenylephrine hydrochloride. The vascular clamps are
then placed on the common, external, and internal ca-
rotid arteries. The superior thyroid artery may be oc-
cluded ternporarily, using a silk suture or a small
Yasargil aneurysm clip. The vascular clamps are then
rotated medially so that the posterior—lateral aspect of the
carotid artery is easily accessible for an arteriotomy.
The arteriotomy is made in the common carotid ar-
tery with a #15 knife blade (Fig. 9A). With angled Pott's
scissors, the longitudinal arteriotomy is continued dis-
tally into the internal carotid artery, until normal intima
is visualized. The exposed atherorna is then dissected
from the arterial wall, using the fine tips of a curved
hemostat (Fig. 9B). This is one of the most important
steps of the operation and requires that the dissection be
in the plane between the diseased intima and media at
the level of the internal elastic lamina (80). Here, one
must avoid entering the plane between media and the
adventitia, as this will not allow for a smooth feathering
of the distal diseased intima from the more normal in-
tima in the distal internal carotid artery. Once this
proper plane is found, it should be developed circumfer-
entially and the atheroma sharply divided at a conve-
nient point (Figs. 9C and D). Next, the atheroma is dis-
sected away frorn the arterial wall, using gentle traction
and the smooth action of the pointed hernostat so that
the plaque is dissected from the common carotid artery
(Fig. 9E). The assistant maintains exposure by gently sep-
arating the walls of the vessel (Fig. 9F).
The dissection is next carried into the external carotid
artery, where the diseased atheroma is dissected from the
orifice in a circumferential fashion (Fig. 9G). It is un-
usual to obtain a smooth feathering of the intima in the
external carotid, and the atherornatous core is trans-
sected sharply with a pair of scissors (Fig. 9H). The next
and the most crucial portion of the operation is the dis-
section of the distal portion of the plaque from the inter-
nal carotid artery. Once again, the dissection advances
along equal distances on the atherorna, until it thins dis-
tally. At this point, there is a transition of the plaque to a
very superﬁcial plane. Slight retraction on the atheroma
CEREBROVASCULAR OCCLUSIVE DISEASE / 91
and continued dissection usually allows the surgeon to
feather the thinned diseased intima away from more
normal intima (Fig. 91).
The endarterectomy site is irrigated with heparin—sa—
line solution and loose debris is completely removed.
Occasionally, loose tags of circumferential fibers of the
media are dissected, and these must be removed (Fig.
9J). If the distal section of the internal carotid results in a
step—off or a shelf, intimal tack—up sutures are required,
using double—ar1ned 6-0 monofilament sutures to pre-
vent intimal dissection of this distal ﬂap. Prior to closure
of the arteriotomy, each of the clamps on the internal,
common, and external carotid arteries is brieﬂy released
to ascertain patency. The arteriotomy is closed with a
continuous 5-0 monofilament suture. With this tech-
nique, angioplasty is rarely required. If the vessel is ex-
tremely small, one may use a graft obtained from a vein
during initial exposure. The arteriotomy is closed begin-
ning in the internal carotid and preceding proximally
into the common carotid artery (Fig. 9K). Before the
final sutures are tied, each of the clamps is brieﬂy opened
to expel any air or debris.
Following final closure of the arteriotomy, the ﬂow is
restored to the external carotid artery, by opening ﬁrst
the external carotid clamp and then the common carotid
clamp, to expel any remaining debris into the external
circulation. Finally, the clamp on the internal carotid
artery is released and the suture line is inspected. The
anticoagulation is not reversed. Slight bleeding from the
suture line is usually controlled by slight pressure on the
rubber dam. The vessel is carefully palpated for evidence
of a bruit, which would suggest turbulence and require
angiography to rule out an inadequate endarterectomy.
The wound is closed using absorbable suture; a subcu-
ticular skin closure is used for cosrnesis. A drain is
brought out through a separate incision and removed on
the next day.
Vein Patch
If the arteriotomy closure results in any narrowing of
the Vessel lumen, a vein graft should be used without
hesitation. The time required for its incorporation into
the suture line is not signiﬁcant, and it is valuable in
order to obtain a perfect closure. One technical point in
the closure of the arteriotomy with a vein patch is to
ensure that the needle passes from the vein patch side to
the artery, from the intraluminal surface of the internal
carotid to the outside, thereby lessening the chances of
intimal dislodgement. The apical suture—a double-
arrned 5-0 prolene suture—is placed with both needles
passing from the inside to the outside before tying. The
arteriotomy is then closed taking equal 1 mm bites on
each side from the vein to the artery while the assistant
maintains slight tension on the proximal portion of the

Arteriotomy extended
just distal to plaque
Assistant maintaining
gentle traction
Fine-tipped, curved
hemostat
Site of transaction
of plaque
FIG. 9. Surgical technique for carotid endarterectomy. (A) Dotted lines indicate site of arteriotomy on
posterior—lateral aspect of the common carotid artery extending into the internal carotid artery. (B) The
exposed atheroma is dissected from the arterial wall. The proper cleavage plane is between the diseased
intima and media. One must avoid entering the plane between media and adventitia. (C) Cleavage plane
developed circumferentially in the common carotid artery. (D) Site of division of plaque. Sharp transec-
tion with fine—tipped scissors.
92

\\
Assistant/xX, Assistant
Assistant
Gentle traction
FIG. 9. Continued. (E) Dissection of atheroma from the arterial wall. Gentle traction is maintained on the
plaque while it is being dissected away from the common carotid artery by use of the fine tips of the
curved mosquito hemostat in agentle "stroking“ motion. (F) Gentle traction. (G) Dissection of the plaque
into the external carotid artery. The diseased atheroma is dissected from the orifice in a circumferential
fashion. (H) Atheromatous core in external carotid artery transected sharply with a pair of scissors. Cut
segment retracts into external carotid artery after traction is released.
93

94 / CHAPTER?
FIG. 9. Continued. (I) Dissection continues
along equal distances on the atheroma until it
thins distally. The plaque becomes more super-
ficial, and, with light traction and continued dis-
section, the thinned diseased intima is “feath-
ered“ away from more normal appearing
intima. (J) Loose tags of circumferential fibers
are teased away and removed. The endar1erec-
tomy site is irrigated with heparin—sa|ine solu-
tion and loose debris is completely removed. (K)
Arteriotomy is closed.

patch. This requires that the surgeon take backhand bites
on one side of the arteriotorny to ensure that the needle
always passes from the inside—out on the carotid side.
When the patch is about half way closed, the proximal
portion of the patch is tapered and shortened so that the
patch will fit perfectly, without redundancy or balloon-
ing, which might predispose to turbulence or aneu-
rysrnal formation. If a shunt is used, it must be with-
drawn prior to the closure of the arteriotomy. The
closure is accomplished as follows. First, the vascular
clamps are reapplied and the tourniquets removed. The
shunt is withdrawn and the internal carotid artery is al-
lowed to back bleed, and then is reclamped. Before tying
the final knot in the arteriotomy, the external carotid
and common carotid artery clamps are released. Air bub-
bles and debris are allowed to bleed through the arteriot-
orny site as the suture is tied snugly. After about 20 to 30
seconds of ﬂow from the common carotid through the
external carotid artery, the internal carotid clamp is re-
leased.
Cerebral Protection
As I prefer to do this operation under general anesthe-
sia, the technique of determining the safety of temporary
carotid clamping by performing this surgery under local
anesthesia, and asking a patient to move the arm and leg
affected by the side of the carotid lesion, cannot be done.
Some surgeons advocate the routine use of an intralu-
minal shunt because it allows a surgeon to maintain ca-
rotid profusion and to work in a meticulous, nonhurried
fashion (8l,82,83). However, potential complications of
intraluminal shunts include elevation of a ﬂap of distal
intima, ernbolization of air or atheromatous debris, and
poor visualization of the distal endpoint of the athero-
matous plaque, especially in very high bifurcation le-
sions, which could result in a source of subsequent em-
bolic complications. Some surgeons feel that most
neurologic deﬁcits that follow carotid endarterectorny
are the result of technical difficulties with endarterec-
torny (84). We believe that intraluminal shunting should
be done in selected cases when operative monitoring sug-
gests that there is inadequate circulation after carotid
cross—clarnping. Various monitoring methods may be
used, from visual estimation of the quantity and degree
of blood ﬂow of the back bleeding from the internal ca-
rotid artery (85) to very sophisticated techniques of rnea—
suring cerebral blood ﬂow after carotid clamping (86). A
commonly used method to determine adequacy ofcollat—
eral circulation is the measurement of the internal ca-
rotid artery (ICA) stump pressure distal to the point of
cross—clarnping. Unfortunately, there is no agreement as
to the minimal level of stump pressure (87,88). In addi-
tion, the internal carotid artery stump pressure is
thought to be an unreliable index of the cerebral blood
CEREBROVASCULAR OCCLUSIVE DISEASE 95
ﬂow during carotid occlusion, and its relationship to
blood ﬂow may be inﬂuenced by the anesthetic agent
itself (71,89).
The electroencephalogram is a reliable method ofeval—
uating cerebral function during endarterectomy. It is
noninvasive and is a technique for continuous rnonitor—
ing of cerebral function throughout the entire procedure,
including the induction of anesthesia, the operation, and
the postoperative recovery room period. There is a high
correlation between cerebral blood ﬂow during carotid
occlusion and changes in the EEG. With a cerebral blood
ﬂow of 30 cc per 100 gram per minute, the EEG is nor-
mal. When the cerebral blood ﬂow varies between 18
and 30 cc per 100 gram per minute, there are no major
changes. However, occlusion ofthe carotid with the cere-
bral blood ﬂow of less than 18 cc per 100 gram per rnin—
ute is always associated with an EEG abnormality
(70,86).
We believe that the EEG is reliable and, if alterations
in the EEG do occur during the carotid clamping, we
employ an intraluminal shunt. The degree of EEG
changes reﬂects the severity of the ﬂow reduction and is
reversed with replacement of the shunt (70,86).
Intraoperative Intraluminal S/mm
The decision to use an intraluminal shunt during ca-
rotid endarterectorny is an individual one and must con-
sider the availability of accurate inlraoperative rnonitor—
ing of cerebral functions during shunting, if selective
shunting is to be utilized most efficiently. From the data
available on the comparison of various authors‘ experi-
ences, there does not appear to be a strikingly clear ad-
vantage of the various techniques utilized (Table 3).
There is no definitive answer to the question of whether
or not intraoperative strokes are the result of hemody—
narnic ischemia or thromboembolic events. While the
use of the shunt should theoretically prevent hemody—
narnic insufficiency, the mechanical obstruction of the
shunt itselfis cumbersome and can interfere with a rnetic—
ulous surgical dissection of the distal intimal plaque. Al-
though sorne surgeons have demonstrated excellent re-
sults using "no shunt," arguing that the hemodynamic
risk of temporary clamping is extremely low and that
most intraoperative strokes result from embolization
possibly precipitated by the use of an indwelling shunt,
there is clearly a subgroup of patients that during cross-
clarnping of the carotid artery suffer severe hemody—
narnic changes that, if left unattended, will result in per-
manent neurologic sequela (90).
In Ferguson's series of 282 consecutive cases, nine pa-
tients had mean pressures equal to or less than 25 mm of
mercury, and all had EEG changes (90). Four patients
(1.4 percent) awoke with strokes. Of the four strokes, two
were found to be embolic by angiographic and CT rnea—

96 / CHAPTER 7
TABLE 3. Operative stroke and mortality rates in carotid endarterectomy.' A comparison of results
with and without intraoperative shunting
Author/year Procedures
Routine shunt
Thompson, 1979 1,107
Giannotta et al., 1980 152
Selected shunt
Sundteta|.,1981 1,145
Crowell and Ojemann, 1 984 408
No shunt
Baker eta|., 1 977 304
Whitney et al., 1980 1,917
Bland and Lazar, 1 981 280
Alien and Preziosi, 1 981 154
Ferguson et al., 1985 282
Mortality rate % Stroke % Combined %
1.4 1.4 2.8
0.7 2.5 3.2
1.5 2.0 3.5
0.7 2.9 3.6
0.6 1.6 2.2
1.8 0.9 2.7
0.0 1.1 1.1
0.6 0.6 1.2
0.7 1.4 2.1
(From ref. 149, with permission.)
surernents, while two were believed to be hemodynamic
in caus'e. This resulted in an overall risk of hernody—
namic stroke of 0.7 percent. In the patients with severe
EEG changes and a mean stump pressure of 25 mm of
mercury or less, there appeared to be an increased risk of
hemodynamic stroke; use of a shunt in these patients
might have offered some additional cerebral protection.
Spetzler and his co—workers performed 200 consecutive
endarterectomies with a combined morbidity and inor-
tality of 1.5 percent. They used no shunt initially but
utilized barbiturate protection and maintenance of nor-
rnotension with pressor agents. This surgery was per-
formed with the operating microscope. Subsequently,
Spetzler has advocated the use of an intraluminal shunt
in addition to the barbiturate protection in selected
cases (91).
Sundt and his coworkers believe that 80 percent of
their patients would have had a permanent deficit had
intraluminal shunting not been employed (76).
Shunt Placement
Iprefer to use a Javid shunt. The proximal and distal
ends are tapered and fit snugly into the differently sized
lumens of the internal and common carotid arteries,
thereby lessening the chances of dislodgement. The
shunts are held in place by Rummel toumiquets, utiliz-
ing the umbilical tapes previously placed around the
cornrnon, internal, and external carotid arteries. These
umbilical tapes are passed through a 6 in length ofpoly—
ethylene tubing; by sliding the tubing over the umbilical
tapes, one is able to snug down the tubing against the
vessel and internal shunt. The tubing is held in place by a
hemostat, which is placed across the umbilical tape as it
exits from the lumen of the tubing. Prior to arterial
clamping and during the short waiting period after the
intravenous heparin bolus is given, the surgeon and as-
sistant rehearse the technique of shunt placement so that
the procedure will proceed efﬁciently and smoothly.
Following complete heparinization, the vascular
clamps are placed across the common, internal, and ex-
ternal carotid arteries, respectively. Adequate exposure
of these vessels must be obtained so that the clamps and
tourniquets are applied on areas of the vessels free of
atheromatous disease. After the clamps are in place, the
arteriotomy is made from the common carotid into the
internal carotid artery, well above the atheromatous
plaque, so that normal distal intima of the internal ca-
rotid artery is visualized. The distal end of the shunt is
inserted into the distal internal carotid into an area of
normal intima and is advanced just past the arteriotomy.
The internal carotid artery clamp is then released, and
the internal shunt is advanced to the point of the tourni-
quet, while the artery is actively back bleeding. This
should be done smoothly and gently, to avoid creating
an intimal ﬂap. The tourniquet is then snugged down
upon the internal carotid artery, securing the distal end
of the internal shunt. The midportion of the shunt is
then clamped.
The proximal end of the shunt is next inserted into the
lumen of the common carotid artery proximal to the
diseased atheroma. The clamp across the shunt is re-
leased, and the proximal end of the shunt is gently in-
serted into the lumen of the common carotid artery
while actively bleeding, to ﬂush out any air bubbles or
debris in the proximal carotid artery. The shunt is then
reclamped and the tourniquet is snugged down the corn-
mon carotid artery, securing the shunt in place. The
common carotid clamp is released, followed by a gradual
release ofthe clamp across the shunt. This is a critical
time to pay attention to the presence of bubbles or de-
bris, which can be seen in the shunt tube. If these are
present, the shunt is again clamped, the proximal end of
the shunt is again removed, and the internal carotid ar-
tery is allowed to back bleed, ﬂushing out this debris.

One must repeat this procedure until there is no evi-
dence of bubbles or debris passing through the shunt
tube. Once the shunt is in place, a meticulous and un-
hurried endarterectomy is then performed.
To facilitate removal of the shunt after completion of
the endarterectomy, the closure of the arteriotomy is
performed as follows. First, the distal internal carotid
artery is closed, beginning distally and proceeding proxi-
rnally. A second continuous suture is used, starting in the
common carotid artery and proceeding distally. Closure
is continued until there is just enough room for the inter-
nal shunt to protrude. At this point, the vascular clamps
are again reapplied to the common, internal, and exter-
nal carotid arteries respectively. The tourniquets are loos-
ened and the internal shunt is withdrawn. The lumen of
the vessel is copiously irrigated with heparin—saline solu-
tion after each of the vascular clamps is brieﬂy released.
The final few stitches are placed and, before the last su-
ture is tied, the clamps are again brieﬂy released, to ﬂush
the remaining air out of the lumen of the vessel. After the
final suture is tied, the clamps are released first from the
external and then from the common carotid, thus per-
mitting any remaining debris or air to ﬂow into the ex-
ternal circulation. Finally, the internal carotid artery
clamp is released.
Postoperative Monitoring
After the patient is taken to the neurosurgical inten-
sive care unit, careful neurologic evaluation is performed
hourly. Postoperative hypertension, which is frequently
seen following carotid endarterectomy, is treated with
intravenous sodium nitroprusside. Oculoplethysmog—
raphy is performed in the recovery room and periodi-
cally during the postoperative phase. If postoperative hy-
potension develops, a pressor agent is instituted and
colloids are infused. The patient is given aspirin 5 grains
b.i.d. as soon as oral medication can be tolerated and is
usually discharged five to seven days after the operation.
Complications
Complications of carotid endarterectomy may be di-
vided into two general groups: neurologic and non—neu—
rologic. The most serious complication is the aggrava-
tion or development of a neurological deficit. A
common cause of neurologic deficit is related to cerebral
emboli of arteriosclerotic or platelet aggregations from
either excessive or rough manipulation of the carotid ar-
tery during dissection. Improper use of the indwelling
shunt, inadequate ﬂushing of the vessels following clo-
sure of the arteriotomy, or an inadequate endarterec-
tomy resulting in remnants of the circumferential ﬁbers
from the endarterectomy site can be avoided by rneticu—
CEREBROVASCULAR OCCLUSIVE DISEASE / 97
lous dissection of the plaque, the use of ﬁberoptic illu1ni—
nation and magnification, and. as in our choice of tech-
nique, the use of the operating microscope at the end of
the procedure during the final removal of the tiny debris
of plaque in order to establish a definite intimal feather-
ing and avoidance of a "intimal shelf." Gentleness in
dissection and meticulous feathering of the plaque is re-
quired so that a smooth endpoint in the distal internal
carotid artery is achieved.
Another source of surgically related neurologic deﬁcits
is cerebral ischemia, which may be the result of inade-
quate collateral circulation during cross—clamping of the
carotid. If an intraluminal shunt is not routinely used, it
is essential that cerebral monitoring be done to detect the
presence of cerebral ischemia during carotid clamping.
Hypotension, the result of a reﬂex bradycardia during
dissection of the carotid bifurcation, may be prevented
by injecting the carotid sinus with 1 percent lidocaine.
Postoperative causes of neurologic deficits include
thrombosis of the endarterectomized site, hypotension,
uncontrolled hypertension, intracranial hemorrhage,
and brain swelling (92). Clotting of the endarterecto-
mized site is a result of technical error, frequently be-
cause intima has dissected due to inadequate feathering.
This complication may be detected early in the recovery
room by the routine use of oculoplethysmography or by
changes in the EEG. If the patient awakens with a neuro-
logical deficit, he should be taken back to the operating
room immediately, the wound reopened, and the clot
removed. If no thrombosis is found at the operative site,
an intraoperative arteriogram is performed. If, at the
time of surgery, there is a question as to the completeness
of the endarterectomy, intraoperative angiography is nec-
essaiy. Alternatively, Sundt et al. have advocated the use
of retinal artery pressure measurements in the postopera-
tive period (71). If the retinal artery pressures are re-
duced postoperatively, the patient is returned to the
operating room or studied by angiography. Should a neu-
rologic deﬁcit develop in the presence of normal retinal
artery pressure, the patient may be managed with antico-
agulation for 48 to 72 hours, after which the medication
is slowly tapered.
Postoperatively, hypotension may predispose to cere-
bral thrombosis, especially if there is distal stenosis or
tandem lesions (92). Extremely vigorous attention to the
maintenance of normotension must be made with col-
loids and, if necessary, intravenous vasopressors unless
there are cardiac complications that would prevent their
use. Over—sedation, cardiac arrhythmias, and postopera-
tive congestive heart failure are vigorously treated to pre-
vent postoperative hypotension.
Postoperative hypertension can be quite serious and is
a poorly understood phenomenon associated with endar-
terectomy. Towne found an incidence of 19.4 percent of
patients who developed postoperative hypertension (93).

98 / CHAPTER7
The duration of this hypertension was less than four
hours in 30.6 percent and more than twenty—four hours
in 20 percent of patients. Those patients who develop
postoperative hypertension had significantly increased
mortality and risk of neurologic deficit (94). Archie stud-
ied the relationship between early hypertension follow-
ing endarterectomy and intraoperative cerebral ischemia
and concluded that one determinant of early postopera-
tive hypertension is inadequate cerebral circulation dur-
ing carotid clamping (95). Piepgrass et al. reviewed 14
postendarterectomy patients with cerebral hemorrhage
(96). This represented 0.6 percent of 2,362 consecutive
endarterectomies. All hemorrhages occurred ipsilateral
to the operated side, and the "normal perfusion break-
through phenomenon" was found to be present in 86
percent of these patients. Patients thought to be at risk
for this phenomenon had a clinical history of severe ca-
rotid stenosis with poor collateral ﬂow, symptoms sug-
gestive of hemodynamic rather than ernbolic phenome-
non, and postendarterectorny hyperperfusion as
indicated by increased intraoperative cerebral blood
ﬂow. The authors advise strict control of arterial pres-
sures at norrnotensive or even relatively slight hypoten-
sive levels during and immediately postoperatively in
these high—risk patients in order to prevent this cornpli—
cation. Altered coagulation may be responsible for some
hemorrhagic complications. Avoidance of antiplatelet
and anticoagulant medication may be advisable in this
subgroup of high—risk patients. While one explanation
for the development of hemorrhagic infarction may be
the sudden increase of blood ﬂow into an ischemic area
of abnormal brain, others feel that infarction results
from ernbolization (l,97). We meticulously maintain
blood pressure below 200 mm of mercury. Ifrises in
pressure do occur, one should immediately institute in-
travenous sodium nitroprusside (50 mg in 500 cc of 5
percent dextrose and water).
One potentially catastrophic complication ofendarter—
ectorny is disruption of the suture line. Should this oc-
cur, the patient may have a severely compromised air-
way frorn tracheal compression. An airway must be
reestablished and the patient immediately returned to
the operating room for evacuation of the hernatorna and
repair of the arteriotorny. Other causes of postoperative
hematomas include bleeding from the suture line, inse-
cure ligation of vessels divided during surgery, and per-
sistent oozing frorn the deep tissues as the result of pa-
tients being treated with aspirin and other antiplatelet
medications prior to surgery. A drain will not prevent
accumulation of a significant hernatorna. If respiratory
difficulties develop, the patient should be intubated prior
to being transported to the operating room. In our experi-
ence, bedside evacuation of the hematoma should be
avoided, unless the patient has a massive hernatorna and
one is unable to establish an airway at bedside.
Another complication of carotid surgery is injury to
the hypoglossal nerve, which results in postoperative
tongue weakness. Although this can be tolerated unilater-
ally, bilateral hypoglossal injuries can result in serious
morbidity, and the patient may not be able to maintain
an adequate airway (93). For this reason, bilateral ca-
rotid endarterectomy should be staged. If there is unilat-
eral hypoglossal injury, the second carotid endarterec-
tomy should not be performed until normal function
returns to the tongue.
Bilateral vagus nerve injuries may result in acute respi-
ratory obstruction. Patients who undergo a staged bilat-
eral carotid endarterectomy should have visualization of
their vocal cords prior to their second operation.
Occasionally, the mandibular nerve is damaged, espe-
cially during exposure of a high carotid bifurcation. This
may be prevented by curving the superior portion of the
incision posteriorly toward the mastoid process, below
the angle of the mandible.
Recurrent stenosis of the endarterectomy site is being
increasingly recognized as one late complication of ca-
rotid endarterectorny (84,98). Reported rates of resteno-
sis vary, frorn 0 to 9.8 percent (98). At the present time,
the natural history of the restenosed carotid artery is not
known (98). Recurrent stenosis is felt to represent either
rnyointirnal hyperplasia or recurrent atherosclerosis
(99). Recurrent stenosis within the first year is thought to
result from endothelial hyperplasia, the exact etiology of
which is unknown, whereas stenosis occurring later than
one to two years probably results from arteriosclerosis
(98). Noninvasive methods utilizing oculoplethysmog—
raphy and Doppler sonography may detect this cornpli—
cation; angiography is indicated if patients with recur-
rent stenosis develop clinical symptoms. Sundt has
emphasized the high operative complication rate of 10.5
percent and emphasized that surgery should probably
not be done unless the patient is symptomatic or there is
obvious progression of the stenosis (99). He emphasized
the use of a vein—patch angioplasty to possibly prevent
this complication. It was his feeling in a series of opera-
tions for recurrent stenosis that this potential problem
would have been avoided had vein—patch angioplasty
been performed instead of primary closure of the arteriot—
orny at the first endarterectomy (99).
Postendarterectorny aneurysms are usually the result
of endarterectomy with the use of synthetic patch angio-
plasty and are usually related to the use of silk sutures or
the presence of infection. However, this can also occur
with vein angioplasty and endarterectomy with primary
closure (100). The failure of the suture line may result in
a false aneurysm, or the artery itselfrnay further degener-
ate (l0l). The clinical features of this include a pulsatile
mass, dysphagia, cranial nerve compression, and pain.
The pain is usually aching and retro—orbital. These le-
sions may produce ischemic episodes, which are thought

to be due to ernbolization of thrombotic material corn-
ing up from the aneurysmal wall. These aneurysms have
presented with hemorrhage from the pharynx, ear, or
nose (100).
The occurrence of paroxysmal lateralizing epilepti-
form discharges (PLEDs) has been attributed to the resto-
ration of ﬂow through a previously ischemic zone and
most likely represents reactive hyperemia (71). Yourkey
et al. studied 18 patients with focal motor seizures com-
plicating endarterectomy (102). A severe unilateral lread—
ache usually preceded seizure activity, which was usually
followed by a prolonged Todd's paralysis. There was no
relation to perioperative hypertension. Although the
pathogenesis is unclear, it was felt that this phenomenon
represents a regional lryperperfusion syndrome as sug-
gested by Sundt et al. (76,102). To prevent this complica-
tion, higlr—risk patients (grade 4) are placed on proplry—
lactic phenytoin prior to surgery.
Wound infection, an uncommon complication,
usually responds to drainage and antibiotics and usually
remains superficial (71). One complication of postopera-
tive wound infection is false aneurysm.
Results
The morbidity and mortality of carotid endarterec-
tomy has improved markedly since the introduction of
this procedure in the early 1950s. Safe anesthetic and
operative techniques have been established, and indica-
tions exist as to which group should be considered for
surgery. The relative value of surgery over conservative
treatment has been assessed in a randomized series by
the Joint Study of Extracranial Arterial Occlusion (103).
Of 316 patients with transient ischemic attacks, 169 re-
ceived surgical treatment and 147 received medical
treatment. After an average of 42 months follow—up, 15
percent of the surgical group suffered a cerebral infarct,
compared to 14 percent of the medically managed
group. The best results were observed in the subgroup of
94 patients with transient ischemic attacks and unilat-
eral carotid stenosis. There were 45 patients who had
endarterectomy and 49 patients who were treated medi-
cally. Six percent of the surgical patients had a cerebral
infarction, compared to 12 percent of the medically
treated group. In another report, two groups of 125 pa-
tients with carotid TIAs who had surgery and were
placed on aspirin or a placebo were compared (104).
After 24 months, 13 percent of the surgery—placebo
group had had a stroke, while 3 percent of the surgery-
aspirin group had had stroke. This suggests that the best
results for prevention of stroke in the carotid system is
surgery followed by the daily ingestion of aspirin.
In Table 4, the rate of stroke and death complicating
endarterectomy in patients with TIAs is illustrated
CEREBROVASCUUVR OCCLUSIVI DISEASE 99
(85 , 105-1 13). These studies contrast sharply to the stud-
ies in Table 5, which again show— the results of various
authors in different series reported more recently
(99,1 14-121). One can see considerable variation in the
surgical morbidity—mortality, both within and between
these two groups. Several reasons for this variation mav
exist. Some patients were not clearly classiﬁed into a spe-
ciﬁc diagnostic category or assigned speciﬁc indications
for surgery. Complicating risk factors such as obesity.
uncontrolled hypertension, or diabetes, as well as other
medical risk factors, were not subdivided and. lastly, the
data may reﬂect the fact that superior results are ob-
tained by a few good centers that cannot be duplicated in
other centers. It is this very problem, and the unaccept-
ably high morbidity and mortality, that allows us to pose
a serious question that has not been accurately answered:
namely, "Is the risk of stroke without surgery greater
than the risk of stroke with surgery?" The issue of accept-
able complication rates has been addressed by Jonas and
Mass (122). They concluded that a minimal major mor-
bidity/mortality rate of 2.9 percent for carotid endarter-
ectomy would offer a favorable risk/benefit ratio.
Whisnant et al. compared 151 consecutive patients
who underwent carotid endarterectomy for TIA and
were followed for five years (123). This group was corn-
pared to a similar population medically treated. The
stroke rate in the surgical group was 2 percent per year as
compared with the population with TTAs and no sur-
gery, who had a stroke rate of 6 percent per year. The
authors also found that no patient with cerebral blood
ﬂow of 40 cc per 100 grams per minute or greater during
clamping for carotid endarterectomy had stroke during
surgery or during 4.5 years of follow—up (123).
The differences between morbidity and mortality, de-
pending on the preoperative diagnostic category of
stroke patients, have been emphasized by Sundt et al.
(124), who recently reported on 1,935 operations for ca-
rotid stenosis in patients with transient ischemic attacks
(Table 6). These cases were analyzed according to three
types of preoperative risk factors: medical, neurologic,
and radiographic. Medical risk factors included coro-
nary artery disease (including asymptomatic), a recent
myocardial infarction, hypertension greater than 180/
110, chronic obstructive pulmonary disease, physiologic
age greater than 70, and severe obesity. Neurologic risk
factors included a progressing neurologic deﬁcit, a deficit
of less than 24 hours duration, frequent daily TIAs, and
multiple neurologic deficits secondary to multiple cere-
bral infarction. Radiographic risk factors included steno-
sis of the internal carotid artery in the siphon; extensive
involvement of the internal carotid artery, with the
plaque extending more than 3 cm distally into the inter-
nal carotid artery or at the level of the second vertebral
body in a patient with a short, thick neck; occlusion of
the opposite internal carotid artery; or evidence of a soft

100 / CHAPTER?
TABLE 4. Stroke and death complicating endarterectomy in patients with TIA (early series)
Number of patients Mortality % Stroke %
Slekert eta|., 1 963 (1 04) 32 9.4 18.8
Heyman et al., 1967 (105) 8.2 16.3
Young etal., 1 969 (84) 104 4.8 5.8
Thompson etal., 1970 (1 06) 293 1.4 3.4
DeWeese etal., 1971 (107) 187 2.1 11.8
Easton and Sherman, 1977 (1 08) 57 7.0 21.0
Mungas and Baker, 1 977 (1 09) 80 0 2.5
Carmichael, 1980(1 10) 294 0.3 3.4
Parkin,1982(111) 19 0
UK—T|A Study Group, 1982 (1 12) 41 9.8 24.4
TABLE 5. Stroke and death complicating endarterectomy in patients with TIA (later series)
Mortality (%)
Stroke ("/o)
Name/year Number of Patients
Lee, 1988(113) 337
Fode,1986(114) 3,328
Sundt, 1987(98) 1935
(all groups)
Toronto Cerebrovascular Study
Group, 1 986(1 15)
Zuocarello, 1988(1 16)
Thompson, 1 986(74)
Loftus,1988(117) 53
Zeiger,1987(118) 142
Bunt,1984(119) 2oo
Friedmann, 1988(120) 688
148
2
1
O .
°.“.“.“O—“
.66
.2
.3
C>U'1-l>
|—|
TM
.66
4.0
1 .0
3.9
2.0
4.2 (overall)
2.1 (T|As)
2.1 (70 yrs)
0.7
1.5
4.6
2.7 (after 1984)
TABLE 6. Results of carotid endarterectomy forprimary stenosis”—January 1, 1972 to December 21, 1984
Neurological complications
M I"
I ntracerebral Orta lty
. l h ' t k . .
Transient SC emlc S r0 e hemorrhage lschemlc lntracerebral Myocardial
Grade Cases deficit Minor Major Minor Major stroke hemorrhage infarct Other
1 632 5 4 1 O O 0 1 O 0
|| 402 6 4 2 O 1 O O O 0
III 549 10 3 4 1 1 O 1 9 2
IV 352 14 8 8 O 3 3 5 2 2
Totals 1,935 35 1 9 1 5 1 5 3 7 1 1 4
~ Overall, mortality approximately 1 .3 percent; major morbidity is 1 percent and minor morbidity 1 percent in patients with
primary carotid stenosis. This does not include the grade V group of 37 patients with preoperative occlusion and hemiplegia nor
the group of 57 cases with recurrent disease.
Morbidity/Mortality By Grade
Grade1 1 .0%
Grade II 1 8%
Grade III 4.0%
Grade IV 8.5%
(From ref. 150, with permission.)

TABLE 7. Mayo Clinic grading system of preoperative risk
Grade I: Neurologically stable (no neurological
risk factors) with no major medical
or angiographically determined
risks and with unilateral or bilateral
uIcerative—stenotic disease
Neurologically stable with no major
medical risk factors but with
significant angiographically
determined risks
Neurologically stable with major
medical risk factors, with or
without significant angiographically
determined risk
Major neurological risk factors with
or without associated major
medical or angiographically
determined risk
Grade II:
Grade III
Grade IV:
(From ref. 1 51 ,with permission.)
thrombus extending from the ulcerated lesion into the
internal carotid artery. These patients were classified ac-
cording to their preoperative risk factors into four grades
(Table 7).
If one limits surgery to those patients with asyrnptorn—
atic carotid bruits or to those patients with transient is-
chemic attacks who are in grade 1 or grade 2, the surgical
results can indeed be impressive (Table 8) (70,91,
99,125).
However, while the morbidity and mortality of grade
4 patients is significantly higher than other groups, many
people feel that it is this very group of patients who are
potentially at highest risk of having a stroke and there-
fore may be the group that has the most to benefit
(69,124).
Zeiger et al. undertook a prospective review of 142
carotid endarterectomies for transient ischemic attacks
(119). Preoperative assessments were performed using
the Mayo Clinic classiﬁcation. The overall mortality was
1.4 percent and the major stroke rate was 0.7 percent for
TABLE 8. Carotid endarterectomy surgery: Morbidity and
mortality (grades I and II) for patients with TIA or
asymptomatic bruits
Author Cases Stroke Mortality
Sundt, 1987(99)
TIA 632 0.2 0.2
Asymptomatic bruit 402 0.5 0
Thompson, 1983 (125)
TIA 842 1.1 1.4
Asymptomatic bruit 229 O 0
Ojemann, 1975 (70)
TIA 104 1.9 0.9
Asymptomatic bruit
Spetzler, 1986(91)
TIA 54 0 O
Asymptomatic bruit 68 0 0
CEREBROVASCULAR OCCLUSIVE DISEASE / 101
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Years After Onset of TIA
FIG. 10. Graph comparing the stroke—free survival time of
medically and surgically treated groups. A is the expected
stroke rate of grade I and grade II patients after carotid endar-
terectomy; B is the expected stroke rate of grade I, II, III and
IV patients after carotid endarterectomy; C is the expected
stroke rate of grade III and IV patients after carotid endarter-
ectomy; D is the expected stroke rate of grade IV patients; E
is the expected stroke rate of patients treated with best medi-
cal regimen. (From ref. 146, with permission.)
a combined rnortality/rnorbidity of 2.1 percent. In grade
1 and grade 2 patients, there was no morbidity or rnortal—
ity G3ig. 10). The length of time until benefit is achieved
by surgery was determined by comparing the natural his-
tory curve E to the Mayo Clinic grade of their surgical
patients. This illustrates a reduction in the surgically
treated patients of the risk of having a stroke, which in-
creases with time.
EXTRACRANIAL-INTRACRANIAL
BYPASS SURGERY
The extracranial—intracranial bypass (ECIC) is a surgi-
cal procedure that involves the construction of an end-
to—side anastomosis between a branch of the external ca-
rotid and the middle cerebral artery. The superficial
temporal artery is more commonly used, the occipital
artery being used less commonly.
Indications
In our experience, there remains a place for ECIC by-
pass for the treatment of surgically inaccessible giant an-
eurysms and tumors of the skull base where preoperative
internal carotid balloon occlusion during angiography
has demonstrated ischemic intolerance measured clini-
cally and with the use of continuous EEG monitoring.
The use of intralurninal detachable balloons in the treat-
ment of intracranial aneurysms has become increasingly

102 / CHAPTER7
utilized and will become more so as techniques, imaging,
and materials become more sophisticated. The invasive
neuroradiologist and the vascular neurosurgeon will
need to address complicated aneurysms that may require
a combination of intraluminal balloon occlusion per-
formed simultaneously with intracranial bypass grafting
in those cases where major arterial occlusion cannot be
tolerated.
The surgical indications were previously based on the
rationale that this procedure can supply blood to areas of
the brain rendered reversibly ischemic by pathologic
processes not amenable to existing techniques of extra-
cranial vascular surgery. These "tandem" lesions occur
in 20 to 30 percent of all patients undergoing angio-
graphic evaluation of cerebral ischemic episodes, and
range from high—grade stenosis to occlusion of main
branches of the internal carotid artery or branches of the
middle cerebral artery. The following indications have
been previously outlined:
1. Focal TIAs with signs and symptoms related to an
inaccessible internal carotid artery or middle cerebral
artery (MCA) stenosis or occlusion.
2. Slow strokes, in which there is progressive neurologic
dysfunction often mimicking symptoms of a space-
occupying lesion. The neurologic deficits are related
to ischemia in the watershed zone of cerebral perfu-
sion and are believed to result from the failure of ade-
quate collateral circulation, usually in patients with
multiple vascular occlusions.
3. Planned occlusion: Initial bypass grafting may be
needed to provide cerebral collaterals when carotid or
MCA occlusion must be done for aneurysm or tumor
of the skull base.
4. Progressive dementia: Multiple occlusions may cause
hypoperfusion with dementia. Superficial temporal
artery—middle cerebral artery grafting may reverse
such syndromes.
5. Acute stroke.
As a result of the cooperative ECIC bypass study, these
indications are no longer believed to be entirely valid.
However, in our experience, there remains a place for
ECIC bypass in the treatment of some surgically inacces-
sible giant aneurysms and tumors of the skull base, as
noted earlier. In addition to these patients, patients with
bilateral carotid occlusions with inadequate collateral
circulation and progression of symptoms despite opti-
mum rnedical management may benefit from cerebro—
Vascular augmentation. Contraindications include a
moderate to severe fixed deficit, a superficial temporal
artery or middle cerebral artery branch less than 0.8 mm
in diameter, multiple occlusions due to thromboembolic
disease, severe cardiopulmonary disease, and uncon-
trolled diabetes or hypertension.
Surgical Technique
Anesthesia and Patient Positioning
The induction of general anesthesia is done cau-
tiously, to avoid precipitous drops in blood pressure,
which, in the presence of occlusive vascular disease,
might result in a catastrophic ischemic event. A central
venous catheter is inserted, along with a radial artery
catheter, to measure systemic arterial pressure accu-
rately and to obtain arterial blood gas samples. Normo—
carbia (avoiding hyperventilation) is used to prevent col-
lapse of the brain surface from the craniectomy site. A
Foley catheter is inserted. A large roll is placed under the
shoulder and back to maintain the body at an angle of
about 45 degrees from the horizontal. This maneuver
will permit the head to be turned to a full lateral position,
without causing compression of the opposite carotid ar-
tery (l26). The head is held in place with three—point
skeletal fixation, with the lateral surface ofthe skull paral-
lel to the ﬂoor. In individuals with extremely short necks
or severe cervical arthritis, this can be achieved by tilting
the table until the full lateral position is obtained. Follow-
ing this, the scalp is shaved and the course of the superfi-
cial temporal artery is mapped out. If the vessel cannot
be palpated, the course of this vessel can be determined
by using a Doppler probe.
Consulting the angiogram, one can select the appro-
priate branch of the superficial temporal artery. Usually
the larger of the two major branches is selected. Prior to
surgery, the patient is started on aspirin 5 grains b.i.d.
andphenytoin J OO mg t.i.d. This is continued during the
postoperative period.
Equipment
The operating microscope with a 200 mm objective
and angled oculars with l2.5X eyepieces is used. Micro-
bipolar coagulation forceps are necessary for precise he-
rnostasis. A #5 jewelers forceps and 5 inch iris scissors
are well suited for preparation of the small scalp arteries.
A small razor—blade knife is used to incise the cortical
vessel. Fine silastic tubing (0.025 inch outside diameter)
is used as a stent during suturing. The anastomosis is
performed with a 5 inch curved needle holder and 10-0
rnonoﬁlarnent nylon sutures.
Surgical Procedure
The superficial temporal artery dissection is the first
step in the procedure. The operating microscope is
brought into the field, and a small incision is made over
.the most distal portion ofthe superﬁcial temporal artery.

The incision is carried through the skin just superficial to
the loose connective tissue, and the superficial temporal
artery is located. A dissection plane is developed above
this vessel, and, as the surgeon works away from himself,
he stays superﬁcial to the artery, dissecting the scalp
away from it and continuing the skin incision proxi-
rnally as he does so. In this way, the incision hes directly
over the vessel and is used to expose the superﬁcial tern-
poral artery in its entirety. Small Gelpi retractors are
used to maintain adequate exposure (Fig. 11A). The as-
sistant interrnittently drips 1 percent lidocaine lrydro—
chloride over the temporal artery to keep it moist and to
prevent spasm. The dissection along the lateral aspect of
the vessel is performed next. A generous cuff of connec-
tive tissue with its vasovasorurn is preserved on the su-
perficial temporal artery. The bilateral dissection is
carried down to the temporalis fascia, along the entire
length of the superﬁcial temporal artery. Numerous side
branches must be coagulated and divided; larger
branches are ligated and divided. The last stage consists
of mobilizing the undersurface of the superficial tern-
poral artery. This is done quite easily when the artery
along with its adventitial vascular cuff is dissected from
the temporalis fascia (Fig. 1 IB).
Following dissection of the superficial temporal ar-
tery, excess adventitia is removed from the distal end.
The rnidportion of the superficial temporal artery is oc-
cluded with a temporary aneurysm clip. The most distal
portion of the vessel is ligated with a 2-0 silk suture, and
the portion of the superﬁcial temporal artery that had
been cleaned is transected in a single 45 degree oblique
cut with microscissors, using higher magnification (Fig.
11C). The vascular clip is brieﬂy released to ensure the
patency of the temporal artery. The clip is reapplied and
the lumen of the superﬁcial temporal artery is copiously
irrigated with heparin—saline solution, using a blunt-
tipped 27 gauge needle attached to a tuberculin syringe.
The vessel is then carefully wrapped in a piece of moist
sponge rotated away from the operative site and kept
moist with 1 percent lidocaine until time for anas—
tomosis.
A T—shaped opening is made in the underlying tern-
poral muscle, and, after the muscle ﬂap is reﬂected (Fig.
1 ID), a craniectorny is made, centered 6 cm above the
external auditory canal for exposure of the posterior end
of the sylvian fissure. Here, the terminal MCA branches
(posterior parietal, angular, and posterior temporal)
emerge from the fissure to spread over the cortical sur-
face of the brain. Previous studies have shown that in a 4
cm diameter craniotomy so situated, cortical vessels may
be found that are larger than 1 mm (127).
The dura is then opened in a stellate fashion and
tented—up along the bony margin for hemostasis. A corti-
cal recipient artery is found, intimately bound and en-
tangled within a complex array of arachnoidal ﬁbers.
CEREBROVASCULAR OCCLUSIVE DISEASE / 103
These are precisely identified and divided to free the cor-
tical vessel (Fig. 11E).
A few penetrating branches must be sacriﬁced during
dissection. They are coagulated with the bipolar forceps
and divided. A rubber dam is placed beneath the cortical
recipient vessel, and, after being irrigated with papaver—
ine, two temporary vascular clips (Kleinert—Kuntz) are
applied, exposing a 1 cm segment of cortical vessel.
The last stage of preparation of the cortical vessel in-
volves making a longitudinal arteriotomy under higher
magnification (Fig. 1 IF). The incision is lengthened by
using straiglrt—tipped rnicroscissors (Fig. 11G). After the
vessel is irrigated with heparin—saline, a segment of silas—
tic stent tubing, cut 2 mm longer than the arteriotomy, is
inserted into the vessel (Fig. 11H).
The superﬁcial temporal artery is spatulated (Fig. 111)
so that the diameter of the oriﬁce is the length of the
arteriotomy of the cortical vessel. Anastomosis is carried
out with the bevel aiming toward the origin of the middle
cerebral artery. After interrupted corner sutures are
placed and tied (Fig. 11J), six to eight additional sutures
are placed along the back wall, taking a little thicker bite
on the STA side to promote intima—to—intima approxi-
mation (Fig. 11K). Sutures are placed more closely to-
gether at the corners, where leaks have a tendency to
occur (Fig. 11L). After completion of the suturing of the
back wall, the front wall is exposed and the suture line
completed. Before the remaining sutures are tied, the
stent is removed (Fig. 11M) and the lumen ﬂooded with
heparin—saline. The STA is brieﬂy opened to expel clots
and air. The distal MCA clip is removed first, followed
by the proximal MCA clip. The suture line is inspected
for leaks. If no leaks are seen, the STA clip is removed
(Fig.1 1N).
The dura and muscles are closed loosely to prevent
kinking of the STA. The galea and skin are closed with
uninterrupted, absorbable sutures. A drain is not used.
Postoperative Blood Flow
Postoperatively, arterial blood pressure is maintained
at normotensive levels, using colloids, ﬂuids, and dopa-
mine if hypotension is present, and nitroprusside to
lower blood pressure if severe hypertension develops. A
major concern postoperatively is the ability of such a
small anastornosis to augment significantly the middle
cerebral artery blood ﬂow, which, in normal individuals,
ranges between 120 and 170 cc per minute (128,129).
In some patients in whom ﬂow has been measured in
the superficial temporal artery while undergoing ECIC
bypass, ﬂow in the open—ended vessels have ranged from
25 to 70 cc per minute (130-133). These ﬁgures are prob-
ably higher than actual ﬂows, as they assume absence of
distal resistance, which would be present in a patent anas—

Wide cuff of adventitja
preserving vaso-vasorum
of STA
Distal STA tip freed -
Of 3dVe“TiTi-3 Dotted lines indicate
incisions in temporalis
muscle
FIG. 1 1 . Surgical technique forSTA—MCA. (A) Superficial temporal artery is exposed; (B) STA along with
adventitial cuff is undermined; (C) STA is obliquely transected, and distal STA tip is freed of adventitia;
(D) incisions in temporalis muscle are made; (E) MCA is prepared; (F) incision is made in MCA; (G) MCA
arteriotomy is extended. (H) Stent is placed; it is cut 2 mm longer than arteriotomy; (I) distal STA is
spatulated; distance D is equal to length of cortical arteriotomy; (J) interrupted corner sutures are placed;
(K) interrupted sutures are placed in back wall; (L) back wall sutures are tied; (M) front wall sutures are
placed and stent is removed prior to tying the final sutures; (N) completed anastomosis: clips are re—.
moved and blood flows in direction of arrows. I

CEREBROVASCULAR OCCLLSIVE DISEASE
FIG. 1 1 . Continued.

106 / CHAPTER?
FIG. 1 1 . Continued.
tomosis to the middle cerebral artery. In an anastoinosed
artery, the blood ﬂow through the superficial temporal
arteiy (using electromagnetic ﬂow meters) has been 1nea—
sured to be between 30 and 35 cc per minute (130-133).
However, many other factors, such as the amount of
collateral blood ﬂow available for middle cerebral artery
distribution, the persistence of perioperative focal vaso-
spasin, and the characteristics of the anastomosis, deter-
mine the amount of collateral ﬂow offered to the he1ni—
sphere by an ECIC bypass (132,134). Although ﬂow is
proportional to the fourth power of the radius of the
conduit, this law is not strictly transferable to the ﬂuid
dynamics in an expansible vessel in a pulsatile ﬂow sys-
tem (48,135). Gratzl et al. and Chater et al. suggest that a
fourfold increase in ﬂow will eventually develop
(136,137). An early postoperative ﬂow of 30 cc per 1nin—
ute would augment the middle cerebral artery ﬂow ap-
proximately 20 percent. A later fourfold increase in ﬂow
may augment the middle cerebral artery ﬂow 80 percent.
Normal cerebral blood ﬂow is approximately 50 to 60 cc
per 100 grams per minute (77,132,138). Neurologic dys-
function occuis secondary to ischemia when CBF drops
to 18 to 22 cc per 100 grams per minute (89). This sug-
gests that restoration of completely normal ﬂow may not
be prerequisite to clinical success of a revascularization
procedure. Austin et al., Gratzl et al., and Heilbrun et al.
have indicated that most patients with a patent anasto-
inosis have an immediate increase in CBF of about 10 to
20 percent (130,136,139). This level correlates with pre-
dicted values and represents a level of collateral ﬂow suf-
ficient to prevent subsequent occurrence of sy1npto1n—
atic neuronal ischemia (132).

Case Example
Some of the indications and characteristics of the sur-
gery are shown in Figure 12A, illustrating the case of a
62-year-old man who had multiple episodes of transient
left hemiparesis. which cleared without significant resid-
ual neurologic deficits. He had a history of hypertension
and coronary artery disease. His medications included
aspirin, diuretics, and antihypertensive medication. An-
giography revealed total right internal carotid artery oc-
clusion at the bifurcation. Cerebral blood ﬂow rneasure—
ments using the 133Xe inhalation technique (42) showed
generalized reduction in the ipsilateral and contralateral
cerebral hemispheres, with the greatest reductions of
ﬂow observed in the territory of the middle cerebral ar-
tery.
The patient underwent a right STA—MCA bypass. One
week postoperatively, the patient had repeat CBF stud-
ies, which showed a 17 percent increase in mean ﬂow in
the ipsilateral cerebral hemisphere. Angiography done
one week postoperatively revealed excellent filling of the
angular and posterior temporal and parietal segments of
the middle cerebral artery through the graft (Fig. 12B).
The STA enlargement occurred early (seven days postop-
eratively), suggesting marked increase in ﬂow through
this vessel.
Saphenous Vein Bypass Graft
Where the superficial temporal artery is too small or
where immediate high ﬂow demands are required, I
prefer using a segment of the saphenous vein in order to
perform a carotid—middle cerebral artery bypass.
FIG. 12. (A) Complete occlusion of right
CEREBROVASCULAR OCCLUSIVE DISEASE / 107
Technique
The patient is positioned in the supine position with
the head held firmly at three—point skeletal fixation. The
distal saphenous vein is prepared by the second surgical
team while the craniotomy is performed. A standard
frontotemporal craniotomy is made, and, after opening
the dura, the arachnoid over the sylvian fissure is opened
using the operating microscope. Using self—retaining
brain retractors, gentle traction on the frontal and tern-
poral lobes opens the ﬁssure and facilitates exposure of
the middle cerebral artery complex. Usually the larger of
the major limbs of the middle cerebral artery (M2 seg-
ment) is chosen as the recipient vessel. After mobilizing a
1 cm segment of the vessel, a small rubber dam is in-
serted beneath the vessel as described previously in the
technique for the superficial temporal artery bypass.
Exposure of the Carotid Bifurcation
The carotid bifurcation is exposed through a horizon-
tal incision in the neck, and, after isolation of the exter-
nal, internal, and common carotid arteries, umbilical
tapes are placed around each.
Preparation ofthe Sap/ienous Vein
The skin incision is made directly over the saphenous
vein, which is immobilized by incising the connective
tissue several millimeters away from the vessel wall to
minimize trauma to the media. Side branches of the ves-
sel are doubly hgated and divided. Prior to removing the
rim carotid artery at the bifurcation, with nonfilling of intra-
cranial vessels. (B) Postoperative angiogram showing good filling of MCA via bypass. Note the increase
in size of the STA (arrow) compared to preoperative studies.

108 / CHAPTER?
vein, a single suture is threaded along the longitudinal
axis of the vessel within the adventitia to maintain ade-
quate orientation. This fine point, emphasized by Sundt
as "Garrett's line," will allow one to recognize any rota-
tion of the vessel that may occur after the harvested vein
is distended with saline (99).
A subcutaneous tunnel for the vein is made using a *20
French Argyle trochar, from a point anterior to the tra-
gus and superficial to the zygorna into the soft tissue of
the neck, where it is passed through the opening of the
horizontal incision previously made for exposing the ca-
rotid artery. The trochar is removed leaving the plastic
sheath. The saphenous vein is reversed and withdrawn
through the sheath with a 0—si]k suture. The sheath is
then removed. The saphenous vein is then gently dis-
tended with cold heparinized saline while careful atten-
tion is paid to maintaining the orientation ofthe vein in
order to prevent rotation or kinking of the vein graft.
Great care is taken to gently distend the vein to prevent
intimal injury.
Surgical Anastomosis
The distal anastomosis is performed first. The tech-
nique is similar to that employed in the previous descrip-
tion of the superficial te1nporal—1niddle cerebral artery
surgical procedure. The patient is given systemic heparin
(approximately 5,000 to 7,500 units) and thiopental
(250 mg) for cerebral protection. Next, the proximal and
distal temporary clips are applied to the middle cerebral
artery, and a longitudinal arteriotoiny is made, approxi-
mately 8 1n1n in length. After the lumen is inigated with
heparin—saline solution to wash out debris and blood, a
small silastic stent is inserted in the recipient vessel as
described in the STA—MCA anastomosis. The anasto1no—
sis between the saphenous vein and the middle cerebral
arteiy is accomplished in a fashion similar to that done
for the STA—MCA, with the exception that we usually
use continuous sutures rather than interrupted sutures.
After the two corner sutures are placed and tied, a contin-
uous 9-0 rnonofilainent suture is used to accomplish the
anastomosis. The back wall is done first and the sutures
tied. The vein is gently rotated so that the front wall can
be exposed. Wet cottonoids can be placed against the
vein to help maintain this retraction. The front wall is
then approximated. Prior to placing the last few sutures,
the silastic stent is gently removed. The lumen is again
irrigated with a small amount of heparin—saline solution.
The remaining sutures are placed and the sutures are
tied. A small temporary clamp is then placed tangential
to the middle cerebral arteiy as close as possible to the
anastomosis, and ﬂow is restored through the middle
cerebral artery as the clips on the middle cerebral artery
are removed. The next portion of the anastomosis can
then be done in an unhurried fashion. We prefer an end-
to—end anastomosis between the saphenous vein and the
external carotid artery. If there is any size discrepancy,
this can be easily overcome by fish—mouthing the lumen
of one or both of the vessels, and the anastomosis is coin-
pleted by using a continuous 6-0 prolene suture. The
distal clamp on the saphenous vein is then opened to
allow back bleeding into the saphenous vein and to eli1ni—
nate any air bubbles. The clamp on the extemal carotid
artery is then released and the vein graft is gently pal-
pated in order to ascertain patency of the graft. The neck
wound is then closed in layers with a small J ackson—Pratt
drain left in the superficial tissues, brought out through a
separate stab incision. The heparin is not reversed. The
bone ﬂap is carefully replaced with an appropriate small
craniectomy opening made for the passage of the sa-
phenous graft so that no kinking or pressure is placed
upon the vein graft. The scalp is meticulously closed in
layers. Postoperatively, the patient is given 5 grains of
aspirin p.o. daily thereafter to promote graft patency.
Extracranial-Intracranial Bypass Surgery—Results in
the Treatment of Occlusive Vascular Disease
Despite the large numbers of extracranial—intracranial
bypass procedures done in the past, the recent results of a
multicenter randomized trial have done much to restrict
the use of this procedure in all but a few patients in this
country.
ECI C Bypass Study
This speciﬁc trial was designed and carried out to de-
termine whether or not an anastomosis of the superﬁcial
temporal artery to the middle cerebral artery reduced
significantly the rate of stroke and stroke—related death
(17,140). The study examined 1,377 patients with recent
strokes, retinal infarction, or transient ischemic attacks
who had either arteriosclerotic narrowing of the internal
carotid artery or middle cerebral artery. Of these, 714
were randomized and assigned to the best medical care,
and 663 to the same regimen with the addition of cere-
bral bypass surgeiy (Fig. 13). After a peiiod of follow—up
lasting up to 60 months, statistical analysis failed to show
any difference in outcome between the surgically and
medically treated groups (17). Two subgroups ofthe sur-
gical group did worse than those who received only inedi-
cal care: those with severe middle cerebral artery steno—
sis, and those with persistence of symptoms after an
internal carotid occlusion was demonstrated. As a result
of the interpretation of the data submitted for analysis,
the cooperative study group ruled out an effective ad-
vantage for the ECIC bypass operation in the prevention
of stroke (17,140).

0.4..
Study Month
Several ciiticisins of the study have emerged. Sundt
and Ojeinann confirmed the suspicion that as many as
2,572 patients were operated on outside the randomized
trial by physicians involved in the participating centers
(140). The reasons for these exclusions were unclear.
One can theorize that these patients may have been se-
lected for probable benefit and that those entered into
the randomization may have been selected. Winn has
emphasized that the low stroke rate (4.5 percent per
year) in the aspiiin-treated patients suggests that patients
less ill than the typical TIA patient may have been se-
lected for randomization. He also noted that surgery is
designed to augment cerebral blood ﬂow and not to pre-
vent embolic disease and that the causes of the strokes
in the ECIC bypass study group were not precisely
known (141).
Another group of patients may also beneﬁt from sur-
gery: those already on aspirin who are having repeated
TIAs. In the future, cerebral blood ﬂow measurements,
positron emission tomography, and other studies that
can correlate ﬂow—related disorders with clinical ische-
mic events may yet further identify subgroups of patients
who may indeed benefit from augmentation vascular
surgery. Transcranial Doppler techniques as used by
Bishop et al. may identify a subgroup of patients who
have an inadequate compensatory vasodilatation with a
CO2 challenge (i.e., impaired autoregulation) (142).
Complications
Despite the multicentered nature of the study, the to-
tal 30-day morbidity from stroke in the surgical group
was 2.5 percent and the 30-day surgical mortality rate
was 0.6 percent. Major complications included 1nyocar-
dial infarction, permanent neurological deﬁcits, gastroin-
testinal hemorrhage, and pulmonary embolism, and oc-
CEREBRO VASCULAR OCCLUSIVE DISEASE 109
FIG. 13. Results of the primary analysis (all strokes,
both fatal and nonfatal), showing the failure of bypass
between the superficial temporal artery and the mid-
dle cerebral artery to reduce stroke in the surgical
(633 patients) as compared with the medical cohort
(714 patients) after an average follow—up of 55.8
months. The analysis uses Kaplan-Meier cumulative
failure curves. (From ref. 147, with permission.)
curred in about 4 percent of patients (132). The total
morbidity (about 14 percent) also includes transient neu-
rologic deﬁcits, seizures, and minor wound complica-
tions such as scalp necrosis or wound infection. The pa-
tency rate of the ECIC bypass was confirmed by
angiography in 96 percent of the patients operated upon
in the tiial.
REFERENCES
1. Fisher CM. The natural history of carotid occlusion. In: Austin
GM, Thomas CC, eds. Micro-nenmsnrgical anastomosis for cere-
bral ischemia. Springfield, IL: Charles C Thomas, 1976.
2. Kletter G. Extracranial-intracranial bypass operationfor preven-
tion and treatment of stroke. New York: Sp1inger—Verlag, 1979.
3. Todd RB. Account of a case of dissecting aneurysm of the aorta
anno minata and the right carotid arteries giving rise to supression
of urine and white softening of the brain. Medico-Chnrg Trans
1844;27:301-324.
4. Savory WS. Case in a young woman in whom the main arteries of
both upper extremities and of the left side of the neck were
throughout completely obliterated. Med Sm-g Clin Trans
1856;39:205-216.
5. Broadbent WH. Absence of pulsation in both ratial arteries: The
vessels being full of blood. Clin Soc Trans l875:8:l65-168.
6. Chiari H. Vber das verhalten des teilungswinkels der carotis com-
munis bei der endartertis cronica deformans verhandl. d'Dentch
Path 1905;9:326-330.
7. Moniz E. L‘encephalographic arterielle son importance dan
la locatication des tumemrs cerebrales. Rev Neural (Paris)
1972;2:72-90.
8. Fisher CM. Occlusion of the carotid arteries: Further experience.
Arch Neural Psych 1954;72:187-294.
9. Fisher CM. Occlusion of the internal carotid artery. Arch N enrol
Psych 1951:65:346-377.
10. Cairea R, Molins M, Murphy G. The surgical treatment of sponta-
neous thrombosis of the internal carotid artery of the neck: Ca-
rotid-carotideal anastomosis. Report of a case. Ada Nenrol Z,a-
tin0Amerl955;l:7\-78.
11. Stmlly EJ, Hurwitt ES, Blankenberg HW. Thromboendarterec-
tomy from thrombosis of the internal carotid artery of the neck. J
Nenrosnrg 1953;10:474-482.
12. Eastcott HHG, Pickering GW, Rob CG. Reconstiuction ofinter-
nal carotid artery in a patient with intermittent attacks of hemi-
plegia. Lancet 1954;2:994-996.

CHAPTER 8
Brain Tumors
Harold F. Young
I11cide11ce, 113
Etiology, 113
General Symptoms a11d Signs, 114
Tumors of the Glia, 116
Incidence, 116
Astrocytomas and Glioblastomas, 116
Cerebellar Astrocytomas of Childhood, 123
Brainstem Gliomas, 124
Optic Nerve Gliomas, 125
Ependymomas, 126
Oligodendrogliomas, 128
INCIDENCE
The results of an autopsy survey by Russell and Rubin-
stein suggest that 9.2 percent of all tumors are in the
brain and that 49 percent of all primary brain tumors are
gliomas (1). Neoplasms that affect brain tissue may be
classified into three categories: primary intraaxial tu-
mors; extraaxial nonparenchymatous tumors, such as
meningiomas; and metastatic tumors. The first group,
the primary intraaxial tumors, arise primarily fro1n par-
enchymatous elements of the central nervous system
(CNS) and account for approximately 50 percent of all
intracranial tumors. Primary intraaxial tumors have an
incidence of about 5 per 100,000 persons per year, and
about 10,000 of such cases occur each year in the United
States. These tumors rarely metastasize outside the CNS,
probably because of the limited life—span of the patient
following diagnosis and treatment. The incidence of 1net—
astatic tumors to the CNS is clearly increasing, with up
to 65,000 to 70,000 new cases occurring yearly, and will
increase as patients live longer with cancers treated by
chemotherapy. The increased length of survival of these
patients gives longer exposure time for metastatic de-
H. F. Young: Division ofNeur0l0gical Surgery, Medical Col-
lege of Virginia, Virginia Commonwealth University, Rich-
mond, Virginia 23298.
113
Princi les 0fNeur0surgerv,
edite by Robert G. Grossman. R0senberi© 1991.
Published by Raven Press, Ltd., New Yor .
Medulloblastomas, 129
Hemangioblastomas, 132
Papillomas of the Choroid Plexus, 133
Pineal Tumors, 135
Colloid Cysts of the Third Ventricle, 136
Me11i11giomas, 138
Acoustic Neuromas, 149
Craniopharyngiomas, 152
Primary Central Nervous System Lymphomas, 154
MetastaticIntracra11ial Tumors, 155
References, 157
posits to develop a11d many cancer patients now die with
CNS involvement. About 80 percent of patients surviv-
ing two years with s1nall—cell carcinoma of the lung have
CNS metastasis (2). Though many of these metastatic
lesions are asymptomatic, they must be considered in
treatment protocols for these patients. Furthermore,
there is experimental evidence that some chemothera-
peutic agents such as 5—ﬂuorouracil may produce tran-
sient disruption of the blood—brain barrier that enhances
the possibility of CNS metastasis (3). In children under
15 years of age, a United States survey conducted be-
tween 1973 and 1976 revealed that CNS neoplasms had
an incidence of 22.2 per million. Cancer was second only
to accidents as a cause of death in children, and brain
tumors ranked second only to leukemia (which had an
incidence of 37.4 per million) (4). In children, tumors
tend to occur in the posterior fossa, rather than in the
supratentorial compartment where adult tumors are
more frequently found.
Geographic differences have been shown in the occur-
rence of tumors; in Japan an unusually high incidence of
pineal tumors has been reported.
ETIOLOGY
Head trauma as the initiator of the growth of brain
tumors has always been a topic of controversy. In 1888,

114 / CHAPTERS
Byron Brarnwell commented that "amongst the more
direct causes of brain tumor, injury occupies an irnpor—
tant place" (5). Many authors, including Gowers (6),
Kennedy (7), Parker and Kernohan (8), and Gushing
and Eisenhardt (9), have reported cases supporting the
opinion that prior cerebral injury played a role in the
subsequent development of brain neoplasms. Meningio—
mas have been well documented to grow at the exact site
of previous trauma (l0—l2).
Retrospective studies, however, may have a serious
recall bias because patients with brain tumors and their
kin may be motivated to recall and report previous head
injuries more completely than do controls (13). Both
Bailey (14) and Wilson (15) denied any significant associ-
ation between head injury and brain tumor. The possibil-
ity that head trauma predisposes to intracranial neopla-
sia was investigated in 2,953 patients who were followed
for a total of 29,859 person years in the course of a pro-
spective study. The observed number of subsequent
brain tumors, 4, did not differ from the expected number
of 4.1 (16). Also, the location and severity of head inju-
ries did not inﬂuence the subsequent occurrence ofbrain
tumors. Trauma and intracranial meningiomas will be
discussed later.
Tumors can be the result of autosomal inheritance,
which is accepted as the origin for the phacomatoses.
These include von Recklinghausen's neurofibromatosis,
Bourneville's tuberous sclerosis, von Hippel—Lindau's
syndrome, and neurocutaneous melanosis. The associa-
tion of cerebral gliomas and neurofibromas in von Reck-
linghausen's syndrome, as well as cerebellar hemangio—
blastomas in familial von Hippel—Lindau's syndrome, is
well established. Medulloblastoma occurring in siblings
has been described in seven reports (17-20). Yamashita,
Handa, and Toyama have suggested that heredity must
play a role in the etiology of medulloblastoma, or was at
least one of several factors (26). Many have suggested
that genetic factors may be related to the pathogenesis of
intracranial gliomas (22-27) and others have docu-
mented radiation—induced gliomas (28).
Some brain tumors undoubtedly have a prenatal ori-
gin. Craniopharyngiomas, medulloblastomas, and sub-
ependymomas belong in this group. The usual midline
location of these tumors, particularly the midline local-
ization of medulloblastomas and subependymomas, is
striking and suggests origin from the pluripotential cells
of the medullary velum in cases of medulloblastoma and
from subependymal cells in cases of subependymoma.
The fact that identical twin brothers can simultaneously
develop symptoms of a subependymoma, proven at
operation, strongly favors a view that this tumor is in-
deed maldevelopmental in origin (22). There are at least
nine case reports of uniovular twins developing proven
brain tumors, including gliomas, meningiomas, rnedullo—
blastomas, and subependymomas (26).
Suggestive evidence exists of a relationship between
Simian virus 40 (SV—40) and development of a rnedullo—
blastoina in the cerebellum of children. The incidence of
brain tumors in children in Connecticut increased be-
tween 1960 and 1965, but this increase was not 1nain—
tained after 1965. The mothers of many of these children
had been vaccinated during pregnancy with an antipo—
liornyelitis vaccine which had been contaminated with
Simian virus 40. In Connecticut between 1956 and
1962, 120 children under 20 years of age developed tu-
mors of the central nervous system. Medulloblastomas
accounted for 42 percent of the tumors in children
whose mothers had received the contaminated vaccine,
but in only 18 percent of the children who had not been
exposed to SV—40. Sixty—seven percent of the children
with a medulloblastoma had a history of exposure to
SV—40, compared with 21 percent of the children who
had not been exposed (p < 0.01). It is as yet unknown if
those children of exposed mothers who did not develop
tumors in childhood will do so later in life (29).
Brain tumors have been produced in owl monkeys
inoculated with a human poliornavirus (30). Humans
are a natural host for two polioviruses: JC virus, irnpli—
cated in progressive multifocal Icukoencephalopathy
(PML), and BK virus, often isolated from the urine of
immunosuppressed patients. Also, an SV—40—related se-
quence in the DNA and extracted from one human
glioblastoma has been observed (3 l). The finding of such
a viral genome in one human brain tumor does not
prove that a virus is of an etiological importance. Yet,
the proof of viral DNA sequences in a human brain tu-
mor, especially when the virus is known to be oncogenic
in animals, is deserving of further interest.
The etiology of primary brain tumors remains largely
unknown. Brain tumors primarily occur in homo sa-
piens and the carcinogens, such as polycyclic hydrocar-
bons and other compounds, that induce tumors in labo-
ratory animals have not been proven as an etiologic
factor in human brain tumors.
GENERAL SYMPTOMS AND SIGNS
The general symptoms of brain tumors are due to in-
creased intracranial pressure (ICP), traction of the tu-
mor, or brain herniations affecting pain—sensitive intra-
cranial structures—the blood vessels, dura mater, and
cranial nerves. Most of the general symptoms occur only
late in the course of tumor growth and indicate an ad-
vanced stage in tumor progression, except for neuropsy—
chological changes, which may be an early symptom for
brain tumor.
Increase in intracranial pressure may be caused by (l)
the tumor mass, (2) associated cerebral edema, (3) ob-
struction of cerebrospinal ﬂuid (CSF) pathways, (4) ob-
struction of the venous system draining the brain, or (5)
obstruction of the cerebrospinal ﬂuid—absorbing mecha-
nisms. The presence of a tumor mass within the rigid

cranium will increase irrtracrarrial pressure. Iftlre growth
of the neoplasm is slow, the brain and even the cranium
of young children will compensate to some extent for the
additional mass. When the limits of the compensatory
mechanisms are reached, the symptoms of increased ICP
occur. At times, a small mass may be associated with
severe cerebral edema resulting in increased ICP. In gerr-
eral, however, the volume of tumor itself must reach at
least 100 grams before it causes symptoms from irr-
creased ICP.
Cerebral edema is clearly a major component of in-
creased ICP in patients with brain tumor. In fact, some
authors claim that it is the edema associated with the
tumor that is the rnaj or cause of increased ICP. The most
malignant primary irrtraaxial tumors, especially rneta—
static tumors, are associated with white matter edema.
This is vasogenic edema, resulting from leakage of serum
protein through defects in the capillary endothelium. Ste-
roids are effective in reducing the symptoms and signs of
increased ICP in patients with a brain tumor, generally
coincident with a decrease in edema as seen on cornputer—
ized tomography (CT), indicating that the edema is a
major cause of increased ICP in some patients with brain
tumor (2 1).
Tumors in various areas of the brain may cause ob-
struction of CSF ﬂow. Frontal lobe tumors, suprasellar
tumors, and tumors of the anterior third ventricle may
obstruct the foramen of Monro causing enlargement of
the lateral ventricles. Tumors in the temporal lobe may
cause a shift of the brainstern with herniation of the ine-
dial temporal lobe into the irrcisura. Tumors of the poste-
rior third ventricle, quadrigernirral plate, periaqueductal
grey area, and fourth ventricle may cause obstruction of
the aqueduct of Sylvius. Obstruction may also occur at
the foramina of Luschka and Magendie.
Neoplasms occasionally will compress a venous clra1r—
nel, such as the sagittal or transverse sinus, causing a
decrease in spinal ﬂuid absorption and setting up a cycle
in which increasing pressure further compresses venous
channels. Diffuse meningeal neoplasms, such as carcino-
rnatosis of the meninges, may cause decreased absorp-
tion of spinal ﬂuid and increased ICP, usually by produc-
ing hydrocephalus. Finally, a chronically elevated CSF
protein may diminish absorption and can result in irr-
creased ICP.
The clinician must diagnose the tumor, especially the
primary irrtraaxial brain tumor, long before these syrnp—
toms and signs develop in order to cure the patient. Otlr—
erwise, treatment will be largely directed toward relief of
irrtracrarrial hypertension, with loss ofthe opportunity to
cure the patient. Late diagnosis of a tumor is similar to
allowing a patient with an expanding post—traurnatic lre—
rnatorna to develop a dilated pupil or decerebratiorr. As a
result, as in the late diagnosis of a tumor, the patient will
have sustained a secondary brain insult from increased
ICP or brain herniation that was preventable.
BRAIN TUMORS / 115
The general symptoms and signs observed in patients
with brain tumors are as follows:
1. Subtle, gradual change in personality and behavior,
irritability, sornnolence, or lethargy. These symptoms
are seen very early in frontal lobe tumors or as a sign
of increased irrtracrarrial pressure from a posterior
fossa tumor causing hydrocephalus. In children, there
may be deterioration in school performance. These
symptoms often go unrecognized for weeks or
months and are usually more apparent retrospec-
tively upon development of other neurological syrnp—
toms.
2. Headache. Headache may be a generalized sign of
increased irrtracrarrial pressure, or it may localize to
the site of the tumor. It is usually described as a
chronic deep pain rather than the superficial or ba1rd—
like sensation of a tension headache. The headache
caused by generalized increase in irrtracranial pres-
sure usually occurs orr a daily basis and is especially
prominent in the morning upon awakirrg from sleep.
The headache secondary to increased ICP is usually
associated with papillederna. In children, the lread—
ache is frequently associated with morning vomiting
without nausea. The upright position or even lryper—
ventilation, by lowering arterial Pcoz. may lessen the
severity of the headache. At times, the headache local-
izes to the side or the area of the tumor. This most
often occurs when there is local invasion of dura or
bone by the tumor. Gentle tapping ofthe scalp o%er
the area may aggravate the headache or identify a serr-
sitive area.
3. Vomiting. Vomiting is frequently seen in patients
with increased ICP from a brain tumor. It often oc-
curs with headache, arrd a vomiting episode may actu-
ally relieve the headache. Vomiting is a particularly
common symptom in children with posterior fossa
brain tumors and is usually described as projectile
vomiting. It usually occurs in the morning upon aris-
ing arrd is not associated with nausea.
4. Double vision. Diplopia is frequently a symptom of
bilateral sixth nerve palsies. If the palsies are indeed
bilateral, there is no localizing value to the diplopia as
it is a sign of generalized increased ICP.
5. Seizures. Generalized seizures comprise the initial
symptom in about 15 percent of patients with brain
tumors, and occur sometime during the illness in
about 30 percent of patients with brain tumors.
Whether a tumor will produce seizures depends
largely on its location and growth characteristics. The
patients with a tumor in or near the sensorirnotor
cortex are more likely to have a seizure than patients
with a tumor in a frontal or temporal pole. Focal a1rd/
or J acksonian seizures are often associated with a cere-
bral tumor. Most often, the family or witnesses are
alarmed and describe the seizure in terms of a grand

116 / CHAPTERS
mal seizure. A brain tumor should be strongly sus-
pected in any new seizure disorder occurring in an
adult.
The important speciﬁc symptoms and signs of the
more common brain tumors will be described in the dis-
cussion of the particular tumor.
TUMORS OF THE GLIA
Incidence
The term neuroglia (nerve—glue, or putty) was intro-
duced by Virchow in 1846 (32). Neuroglial tumors may
be of one cell type or may be mixed. The classification of
gliomas, especially the grading of the astrocytic series, is
.still a subject ofdebate. The histopathological tissue anal-
ysis, according to the classifications of Burger and Vogel,
is a schema that is gaining increased acceptance by
neuro—oncologists (33,34). Gliomas account for almost
50 percent of all primary brain tumors. The glioblasto—
rnas account for 12 to 15 percent of all brain tumors, or
33 percent of all tumors of the glia, and are second only
to meningiomas in frequency among primary brain tu-
mors (35). Sorne tumors, including cerebral astrocyto—
mas, may be relatively benign and well differentiated in
early stages but later can become highly malignant neo-
plasms.
Astrocytomas and Glioblastomas
The most common type of gliorna is the astrocytoma
found in the cerebral hemispheres of adults and in the
cerebellar hemispheres of children (36). There are many
classifications of astrocytomas. Bailey and Gushing dif-
ferentiated only two definite histologic types: the fibril-
lary and protoplasmic (37). Penfield recognized three
types of astrocytomas: pilocystic, gemistocytic, and dif-
fuse (38). The pilocystic type is slow growing and forms
the cystic astrocytoma of the cerebellum. The gen1isto—
cytic type is more rapid growing, with multiple small
cysts, and is found only in the cerebrum. The diffuse
astrocytoma is composed of small cells and is generally
found in the cerebrum. Svien and associates suggested
what is apparent to many surgeons, that astrocytomas
appear in various stages of malignancy or anaplasia,
which they graded I to IV (39). The benign astrocytomas
were graded I and II, and the more malignant were
graded III and IV. Glioblastomas are essentially grade IV
astrocytomas in this classification. Other pathologists
grade the astrocytomas as benign or malignant.
Symptoms and Signs
The patient with a tumor of the astrocytoma series,
especially a glioblastorna, may present with a variety of
symptoms, which often are unrecognized for weeks or
months prior to medical attention or correct diagnosis.
Unless the tumor is heralded by a seizure, the patient
often has a very subtle and gradual change in mental
status, which might well be termed psychomotor retar-
dation. This may be noted as a single symptom, such as a
personality or behavior change, apathy, forgetfulness,
dullness, or downgrading in work or school perfor-
mance. As the tumor progresses, often a symptom com-
plex will develop which may include headaches. Unfortu-
nately, these symptoms are often so subtle that they are
ascribed to aging or other events of life and go unrecog-
nized for long periods of time. These symptoms can be
due to a tumor in almost any cerebral location, as cere-
bral gliomas often involve the limbic system, more than
one lobe of the brain, or even both cerebral hemispheres.
There are specific symptoms and signs related to each
area of the brain where the tumor originates and reaches
its maximum size.
Frontal Lobe Intraaxial Tumors
Astrocytomas frequently occur in the frontal lobes
and may spread bilaterally via the corpus callosum (Fig.
1). Tumor infiltration or edema of a frontal lobe, particu-
larly of the right frontal lobe, must involve a fairly large
area of the lobe before headache begins or frank mental
changes occur, although seizures sometimes occur with
minimal cortical involvement. As the tumor increases in
size, bilateral frontal lobe involvement leads to easily
recognizable symptoms of forgetfulness, apathy, and de-
mentia.
Seizures are particularly prone to occur with frontal
lobe gliomas. The tumor may excite the frontal eye field
or the motor cortex, producing a grand mal seizure or
J acksonian march, with the seizure spreading up or
down the contralateral side of the body. In the course of
an adversive seizure, the eyes deviate toward the tonic-
clonic hand. A tumor growing in the nondominant right
frontal lobe usually will be very large by the time of diag-
nosis, although a tumor in the deep frontal midline may
be quite small and yet produce behavioral deﬁcits or
nonﬂuent speech disturbance if the tumor involves the
posterior portion of the left third frontal gyrus corn-
monly known as Broca's area, which forms part of the
frontal operculum. Because of this, tumors of the left
frontal lobe usually are diagnosed earlier than tumors of
the right frontal lobe.
Temporal Lobe Intraaxial Tumors
The temporal lobe is involved in about one—half of all
the infiltrating neoplasms of the central nervous system.
Lesions of the temporal lobe may produce complex
symptoms including the uncinate seizure, characterized

FIG. 1 . Deep midline glioblastoma, extending across midline
(arrow), making total removal impossible by operation. Note
surrounding cerebral edema, especially in right cerebral hemi-
sphere.
by the subjective sensation of an odor, usually of an un-
pleasant nature. Uncinate seizures occur primarily with
lesions of the arnygdala and the hippocampal gyrus of
either the dominant or nondominant temporal lobe. The
seizure may spread to adjacent areas and psychomotor
seizures may develop. Chewing movements, lip smack-
ing, salivation, and motor automatisms may be part of
the complex.
As the neoplasm enlarges, it may involve Meyer's loop
of the visual pathway in the posterior temporal lobe, pro-
ducing a wedge—shaped defect in the contralateral supe-
rior temporal quadrant visual field. This is because
Meyer's loop contains visual ﬁbers that pass from the
lateral geniculate nucleus of the thalamus to the calca-
rine cortex of the occipital lobe. Only fibers carrying vi-
sual impulses frorn the inferior retina pass into the ante-
rior temporal lobe.
The temporal lobes are involved in processing of rnern—
ory and difficulty with memory, particularly short—term
recall, may occur.
The posterior part of the dominant superior temporal
gyms, known as Wernicke's area, is concerned with lan-
guage. Sorne degree of aphasia may be produced by poste-
rior ternporal—parietal tumors. The speech output is
characterized by ﬂuency, usually with a high normal or
even excessive output of words per minute.
Parietal Lobe Intraaxial Tumors
The parietal cortex receives, correlates, synthesizes,
and elaborates the primary sensory impulses. It is not
BRAIN TUMORS / 117
concerned with the cruder sensations, such as recogni-
tion of pain and temperature, which are subseryed to a
larger degree by the thalamus. Involvement of the post-
central portion of the parietal lobe produces defects in
gnostic or discrimination of sensation. The patient is un-
able to recognize familiar objects by their weight, size,
shape, or texture (astereognosis). Postural sensitivity is
impaired and the patient may not appreciate the exact
position ofhis limbs. Although the simple sensory rnodal—
ities of pain, temperature, and touch are preserved, two-
point discrimination and localization of touch may be
altered. Spatial cutaneous perception may be disturbed
on the contralateral side ofthe body, and the patient may
be unable to indicate where the touch is applied (atopog—
nosis). When two symmetrical areas of the body are si-
multaneously stirnulated, only the stimulus on the nor-
mal side is appreciated (tactile inattention). Usually, the
sensory disorder is more manifest in the distal portions
of the limbs than elsewhere.
Lesions of the parietal lobe may also result in distur-
bance of body awareness, such as unilateral neglect with
a poverty of movement and abnormal positioning of the
limbs, lack of concern over the presence of a one—sided
weakness, or actual denial of hemiparesis (anosognosia).
This usually involves the left body from a right—sided
brain lesion and is again most pronounced in the limbs.
A dressing apraxia is uncommonly observed wherein the
patient has difficulty dressing. One variety of dressing
apraxia is characterized by unilateral neglect. The pa-
tient carefully dresses and grooms one—half of the body,
the side ipsilateral to the cerebral lesion, and completely
ignores the other side. The second variety of dressing
apraxia is exemplified by the patient who is unable to
manipulate an article of clothing in space. This type of
dressing apraxia represents a severe form of visual—spa—
tial disorientation and is seen almost exclusively in cases
with nondominant parietal disorders. A lesion in the an-
gular gyrus of the dominant hemisphere will result in
Gerstmann's syndrome, which is manifest by finger
agnosia, left—right disorientation of the entire body,
agraphia, and acalculia. Lesions of the supramarginal
gyms may produce an apraxia which is usually asso-
ciated with a hemiparesis.
Visual disturbance caused by parietal lobe involve-
ment is usually a lower quadrant homonymous field de-
fect from involvement of the uppermost fibers of the
visual radiations as they project laterally around the pos-
terior horn of the ventricle. Usually, the hemianopsia is
incongruous. Sometimes images are distorted as to size,
shape, or color (metamorphopsia).
Lesions situated near the sensory cortex may cause
sensory seizures of the contralateral side of the body.
This are usually paroxysmal dyesthesias commonly in-
volving the face. Sensory seizures appear as numbness,
heaviness, or pain in the involved limbs. These sensory
seizures are clinically of localizing value when they as-

118 / CHAPTERS
sume the manifestations of a sensory aura preceding a
J acksonian convulsion or when they constitute a focal
sensory seizure alone.
Occipital Lobe Intraaxial Tumors
The bccipital lobe and the preoccipital areas (Brod-
rnann's 18 and 19) are associated with vision and follow-
ing rnovernents with the eyes. The function ofthe preoc-
cipital eye ﬁelds is to push the eyes toward the opposite
visual ﬁeld while following movement. The upper lip of
the calcarine fissure in the occipital lobe contains corti-
cal representation of vision from the inferior nasal retina
of the opposite eye and the inferior temporal retina of the
ipsilateral eye. The inferior lip contains corresponding
fibers from the superior retina.
The field defects associated with neoplasms are often
incomplete, progressive in nature, and have gradual or
sloping margins. Occasionally, they are incongruous but,
in general, a lesion of one occipital lobe will cause a con-
tralateral hemianopsia. Ifthe involvement is limited or
localized to the cuneus of the upper lip of the calcarine
fissure, there is a contralateral lower quadrantanopsia. If
the involvement is limited to the lingual or the lower lip
of the calcarine ﬁssure, there is a contralateral upper
quadrantanopsia. A lesion at the occipital pole will
mainly affect central vision; focal lesions of the occipital
lobes may produce localized loss of vision. Occasionally,
sparing of the macula is seen in hemianopsia associated
with involvement ofthe posterior portion ofthe occipital
lobe. Patients with lesions peripheral to but not truly
involving the striate cortex may have difficulty with fixa-
tion and maintaining visual attention, and they may lose
following and reﬂex ocular movements. These uncoor-
dinated movements can best be demonstrated using the
opticokinetic drum. Under normal conditions, the eye
ﬁxes on the object imprinted on the drum and follows it
around the visual field. Jerky, uncoordinated rnove—
ments are characteristic of destructive lesions of the
preoccipital areas. Patients may also have loss of stereo-
scopic vision, impairment of visual memory and recall,
difficulty in accurate discernment or localization of ob-
jects, disturbances of spatial orientation, and loss of abil-
ity to discriminate with respect to size, shape, and color.
At times, simultagnosia—the inability to perceive more
than one object at a time, or, the ability to recognize
speciﬁc details of a picture but not the entire picture—is
found.
Stimulation or irritation of the calcarine cortex may
produce unformed visual hallucinations, such as ﬂashes
of light, in the corresponding ﬁeld of vision; irritation of
the surrounding areas may cause formed visual halluci-
nations.
Pathology
The histology of the astrocytoma is relevant for the
neurosurgeon performing the operation and for plan-
ning postoperative adjunctive therapy, which usually in-
volves irradiation or chemotherapy. The biological activ-
ity of an astrocytoma appears to be unique to each
patient and is generally related to the actual histology of
the tumor. Low—grade astrocytomas (Grades I and H of
Kernohan) are usually found in younger patients in the
age range of 20 to 40 years. These patients have many
years of useful life after diagnosis and have a normal
immune system (40-44). Whether these tumors cascade
into anaplastic or well—differentiated astrocytomas has
long been discussed. There is no doubt that some con-
tinue to spread slowly as low—grade astrocytomas, eventu-
ally causing death by mass—lesion effect or by infiltrating
vital brain structures. On the other hand, a tumor that
has been demonstrated to be a low— grade astrocytoma by
adequate biopsy or subtotal resection can be found to be
glioblastoma multiforme at the time of reoperation or
death of the patient. Other patients may have a high-
grade astrocytoma that appears to arise de novo as a glio-
blastoma multiforme, with a corresponding rapid and
relentless course. Some patients even have multifocal
gliomas (45).
The glioblastoma multiforme must be regarded as a
heterogeneous tumor in the biological sense. The hetero-
geneity ofthe tumor, characterized by giant cells, mitotic
activity, pleomorphic pseudopalisading, and neovascu—
larity with hyalinization of blood vessels, has long been
recognized (46). The many genotypically and phenotypi—
cally different cell populations of this tumor have also
been well documented (47). The cell—cycle time may
vary from 25 hours to as long as 58 hours. Hoshino and
associates, using ﬂow cytometry, demonstrated that
glioblastomas have a substantial population of cells in
DNA synthesis and a highly variable distribution of
ploidy, consisting not only of diploid and/or aneuploid,
but also of triploid, tetraploid, and possibly octaploid
populations (48). These investigators, as well as Zuber,
Hamon, and Tribolet, who used the Ki—67 monoclonal
antibody directed against a nuclear antigen present only
in proliferating cells during the G[ S.G2 and M phases of
the cell cycle, demonstrated a high variability in the pro-
liferating—cell index of gliomas (49). In routine neuro-
pathological study, the grading of gliomas is presently
done on the basis of morphological criteria, such as nu-
clear morphology, vascular proliferation, necrosis, and
mitotic activity although mitoses are not frequently ob-
served. In the future, in vitro and in vivo cell kinetic stud-
ies will need to be done if proper therapeutic strategies
are to be developed.
Other evidence of cellular heterogeneity has been sup-
plied by the Brain Tumor Study Group (50). In this

study, systemic 1,3—bis (2—chloroethyl)—l—nitrosourea
(BCNU) was identified as the current best chemothera-
peutic agent for patients with anaplastic astrocytomas
and glioblastomas. Less than 50 percent of patients in
the valid study group responded to BCNU given intrave-
nously every 5 weeks. Thus, patients with a glioblastoma
may have a wide variety of responses to chemotherapy or
the response may vary in different areas of the same tu-
mor (51,52). The in vitro drug sensitivity studies per-
formed by Rosenblum and Dougherty at the University
of California at San Francisco also demonstrate the vari-
able drug sensitivity of the glioblastoma (53).
Diagnostic Studies
The diagnostic test of choice for a patient with an as-
trocytoma is enhanced computerized tomography (CT)
or enhanced magnetic resonance imaging (MRI). On
CT, astrocytomas demonstrate a uniform depression of
attenuation values. After the administration of contrast
agent, astrocytomas generally enhance above the pre-
contrast density level. Vascularity and necrosis show
good correlation with contrast enhancement in supra-
tentorial astrocytomas. These tumors are usually
surrounded by zones of decreased attenuation of varying
degrees and extent. Also, there is frequently an inner-
most sharply outlined area with extremely low values,
representing cystic components. Calcification of areas of
the tumor may be seen. Unfortunately, the distribution
of cells of a glioblastoma cannot be inferred from CT
images since the "peritumoral" area and low density
can overestimate or underestimate the extent of the
lesion (54).
MRI studies for tumors generally have a reduced sig-
nal on T,—weighted images and an increasing signal on
increasingly T2—weighted images. In gliomas, the cornpo—
nents and surrounding tissue are often but not always
shown best with T2—weighting (Fig. 2).
When the diagnosis of astrocytoma is made by CT or
MRI, cerebral angiography has a limited role for plan-
ning further diagnosis and therapy. Although angiogra-
phy can demonstrate a shift of major cerebral vessels and
tumor stain or neovascularity, this study is often unneces-
sary for surgery.
Operation
The operation for astrocytomas and glioblastomas is
usually limited by the fact that these tumors are neither
circumscribed nor encapsulated. The more necrotic su-
perficial parts of the central tumor are easily resected,
but the more viable periphery and the deep aspects ofthe
tumor usually fade imperceptibly into normal brain tis-
sue. The blood—brain barrier usually remains intact in
BRAIN TUMORS 119
R
FIG. 2. T2 weighted MRI of left temporal lobe astrocytoma.
Preoperative evaluation of MRI indicated that complete surgi-
cal removal was impossible. Patient has done well two years
following partial lobectomy and irradiation treatment.
the peritumoral area, making it difficult to visualize this
area on CT scan or with the microscope during the oper-
ation. Thus, in nearly every operation, the surgeon must
realize that a cure is not affected by gross radical removal
of the tumor.
At present, there remain four indications for surgery:
(1) to establish the histological diagnosis and plan adju-
vant treatment by submitting tissue for detailed labora-
tory analysis; (2) to relieve the symptoms and signs of
increased intracranial pressure and thereby lessen ine-
chanical brain shift and improve neurological function;
(3) to perform cytoreduction to "buy time" for x—ray
therapy and chemotherapy to take effect; and (4) to re-
duce pressure and change tumor kinetics to make the
tumor more sensitive to radiation and chemotherapy.
These indications remain valid at a time when CT and
MRI scans allow increasingly accurate diagnoses, and
steroids are extremely effective in reducing the signs of
increased intracranial pressure.
Gliomas are associated with cerebral edema which is
often extensive. This vasogenic edema, caused by leak-
age of protein across the defective blood brain barrier, is
the partial cause of the increased intracranial pressure
and neurological defects seen in patients with gliomas.
Brock has shown that even slight local brain cornpres—
sion over short periods of time gives rise to cerebral
edema and a decrease in regional cerebral blood ﬂow
(55). The cerebral edema and increased ICP should be
reduced by the use of steroid administration three to five
days before the operation. Miller and coworkers, in a
study of methylprednisone treatment of 10 patients with
brain tumors, showed that clinical improvement and re-
duction in periventricular elastance occurred within 24

120 / CHAPTER8
hours of treatment, but that ICP was not significantly
reduced until the second day of therapy (56).
The plateau wave is one of the ICP waveforms ob-
served in patients with increased ICP from various
causes. Matsuda, Yoweda, Handa, and Gotoh found a
remarkable decrease in cerebrovascular resistance dur-
ing the plateau wave, concluding that plateau waves are
caused by marked cerebral vasodilation (57). This sup-
ports the thesis that cerebral blood voluine is increased
during the plateau waves. Plateau waves are observed in
brain tumor patients with severe increases in ICP, on a
cl1ronic basis, and may well account for the paroxysmal
systems such as seveie headaches with vomiting. Suffi-
cient administration of preoperative steroids will reduce
or abolish these plateau waves as has been shown in pa-
tients having ICP monitoring prior to operation.
Cerebral Metabolism
The neurosurgeon who cares for the patient with a
brain tumor must not only be able to evaluate the patient
clinically and interpret radiological studies, but must
also understand how cerebral metabolic parameters are
altered by surgery.
In patients with brain tumors who do not have clinical
signs of increased ICP, CSF acid—base status and cerebral
gas exchange are almost normal. With increased ICP,
there are changes in cerebral metabolism and cerebral
circulation. Increase in ICP is associated with a decrease
in cerebral blood ﬂow and an increase of lactate concen-
tration and lactate/pyruvate ratio in brain tissue and
CSF (58). A decrease in cerebral venous pH and P02 and
an increase in Pcoz, lactate concentration, and lactate to
pyruvate ratio have been observed with increased ICP.
After reduction of abnormal ICP, a reactive hyperemia
develops with a further increase in the concentration of
lactate and in the lactate/pyruvate ratio in brain tissue
and CSF. This reactive hyperemia is believed to be
caused by cerebral extracellular acidosis. Following an
operation on a patient with a brain tumor, a further de-
crease in brain oxygenation and an increase in brain aci-
dosis has been demonstrated, suggesting an additional
decrease in cerebral blood ﬂow. In this study, the CSF
metabolic acidosis was most pronounced during the sec-
ond and third postoperative days. The degree of CSF
metabolic acidosis was closely related to an altered level
of consciousness and to outcome. In all fatal cases, post-
mortem study revealed cerebral edema (5 8).
Acidosis may contribute to the development of cere-
bral edema through two different mechanisms. In acido-
sis, cation transport across the cell membrane is i1n—
paired, causing an increase of sodium in the cells and
subsequent intracellular edema. The other possible
mechanism is that extracellular acidosis causes dilation
of arterioles and an increase of cerebral blood volume,
resulting in increased ICP and extracellular edema
caused by plasma extravasation through the damaged
vessels.
Anesthesia
The choice of anesthetic for a patient with a brain
tumor must take into account the fact that the tumor has
caused many intracranial metabolic and physiologic
changes, the most notably high ICP, even following the
extended use of steroid medication preoperatively (59).
The current anesthetic of choice is a balanced barbitu-
rate—narcotic—N2O anesthetic technique, using pentothal
induction and short—acting narcotics such as sublimaze.
The use of moderate hyperventilation to a Pcoz of about
28 1nrnHg is helpful in lowering intracranial pressure. In
addition, the use of both osmotic and distal—loop di-
uretics is recommended, with electrolyte monitoring to
recognize and treat serum electrolyte changes. Mannitol
is given in a 20—percent solution at a dosage schedule of 1
gm/kg. Furosemide (Lasix) is then given to promote tu-
bular diuresis; thus, ICP reduction is caused by ﬂuid shift
from the brain into the vascular system.
In patients undergoing operation on the brain, certain
monitoring techniques are routinely employed. Patients
are monitored with electrocardiography and peripheral
arterial and central venous pressure lines, intermittent
arterial blood gases, expiratory CO2 levels, and urinary
output. A patient placed in any position that might allow
intracranial air embolism should have additional moni-
toring with a precordial Doppler ultrasonic detector and
have a right atrial catheter in place to remove any signifi-
cant air.
Position ofthe Patient
The position of the patient for operation depends, of
course, on the location of the tumor. The tumor should
be ultimately in clear view and in a position that lends
itself to use of the microscope. Each surgeon has prefer-
ences but, in general, if the microscope is used, then 3-
point cranial fixation is important to prevent move-
ment. The head should always be slightly above the level
of the heart to promote good venous drainage. An unob-
structed airway is of utmost importance, and good com-
munication with the anesthesiologist is essential
throughout the entire operation. The head should never
be turned or fixed in such a manner that would occlude
jugular venous return from the head, regardless of the
type of ﬂexible endotracheal tube used. Armored endo-
tracheal tubes should be used to prevent kinking and
occlusion of the airway.
Generally, the patient is in a recumbent, supine, or
semisitting position. The sitting position is still used for
some posterior fossa operations, but should not be used
without the techniques noted above to detect air e1nbo—
lism. Also, there is risk of cord damage caused by neck

ﬂexion in the sitting position, especially in elderly pa-
tients with cervical spondylitic ridges. Quadriplegia has
been reported after operations performed in the sitting
position (60). Preoperative testing of the awake patient
to assess the ability of the patient to sit in the operative
position for 15 to 20 minutes without producing neuro-
logical symptoms may be valuable. When a patient dete-
riorates after posterior fossa surgery performed in the
sitting position, tension pneumocephalus should be con-
sidered. As cerebrospinal ﬂuid is evacuated intraopera—
tively, air enters the potential subdural space. With the
closure of the operative wound, air is loculated intracra—
nially and eventually dissects frontally because of the
usual supine position of the patient following surgery.
Nitrous oxide used for anesthesia will rapidly diffuse into
a cavity to equilibrate the partial pressure of N20 with
that in the blood. Thus, N20 anesthesia may potentiate
tension pneumocephalus by increasing the volume of
intracranial gas (61). This may result in focal deficit or
generalized neurologic deterioration associated with in-
creased ICP. The treatment is twist—drill aspiration of
the air.
Technique
Unless the tumor is small, difficult to locate, or deep
near the rnidline, surgery for gliomas is generally not
nearly as complicated as surgery for most other brain
tumors. In operations for gliomas, the craniotomy is
placed directly over the tumor that has been localized by
analysis of the preoperative studies and by considering
the appearance ofthe exposed cortical and vascular anat-
omy. Locating the tumor by ultrasound is rarely neces-
sary. Usually, the cortical incision is placed into, or i1n—
BRAIN TUMORS 121
mediately adjacent and parallel to the sulcus overlying
the tumor, sparing important arteries and veins. Every
effort is taken to avoid the eloquent areas of the brain
serving speech and motor functions. It is best to ap-
proach the tumor through the shortest route possible so
as not to undermine wide cortical areas. Supratentorial
gliomas are generally not well circumscribed and are
without a sharp plane of cleavage between the tumor and
the adjacent sulcus (Fig. 3) or the underlying edematous
white matter. Using magnification, dissection is possible
along the indistinct cleavage planes, and the tumor
usually can be successfully freed grossly from all sides
except along the base. Unfortunately, anaplastic astrocy—
tornas and glioblastomas have a tendency to blend irnper—
ceptibly with the subependymal white matter and the
ventricular wall making complete removal difficult or
truly impossible (62-67). The Cavitron Ultrasonic Sur-
gical Aspirator (CUSA) and lasers are important adjunc-
tive instruments in tumor removal. The aspirator allows
rapid, gentle removal of tissue without unnecessary
trauma to the brain. A C0; laser is a useful adjunct in
evaporating gliomas.
At the conclusion of tumor removal, the operating ini-
croscope should be used to inspect the tumor bed for any
residual tumor tissue that can be vaporized by the CO2
laser. Absolute hemostasis must be achieved before clo-
sure.
Enhanced CT or MRI scans are not only the most
useful studies for evaluating the resectability of a supra-
tentorial glioma and in planning the operation, but they
are also the best postoperative tests to assess the amount
of tumor removed during the operation. The initial post-
operative CT or MRI scan should be performed as soon
as possible after the operation.
FIG. 3. Glioblastoma appearing well de-
marcated on surface of brain, but grossly
and microscopically infiltrating brain in the
deep white matter.

122 / CHAPTERS
Outcome
Salcman surveyed the literature and reported the ine-
dian survival after operation for 1,561 patients with a
glioblastoma to be 6 months, with only 7.5 percent living
at 2 years (68). All mortality curves converge at 18 to 24
months irrespective of treatment, radiotherapy being the
best adjunctive treatment during the first 18 months
(68,69). Anaplastic astrocytoma has a more protracted
course than glioblastomas inultiforine, provided that the
tumor is confined to a unilateral lobar location and ade-
quate treatment is prescribed. Young age at presentation
has been the most significant factor, in addition to histol-
ogy of the tumor, favorably prolonging survival in many
studies of patients with malignant gliomas (70). Retro-
spective reports on the treatment of the gliomas, without
strict histological review by a central pathology group,
are of little value in the discussion of outcome (71). Pro-
spective controlled studies of this tumor by Walker and
the Brain Tumor Study Group are providing data as to
the predictive value of histology, age of the patient, and
neurologic condition of the patient at the time of opera-
tion (50). The data of this group also provide the basis for
present and future chemotherapeutic studies. Unfortu-
nately, one of the most commonly used chemotherapeu-
tic agents for the treatment of patients with anaplastic
astrocytoma, BCNU, is associated with severe pul1no—
nary toxicity (72,73). Thus, it now appears that another
form of therapy, possibly immunotherapy, will be neces-
sary in the treatment of glioblastoma since all current
treatrnents—operation, irradiation, and chemotherapy
—are self—limiting and each leaves residual malignant
tumor cells leading to recurrence of the tumor syrnp—
toms. As yet. however, no form of immunotherapy, in-
cluding the once promising LAK—cell therapy, has been
significantly beneficial to patients with malignant brain
tumors (74).
Reopemtion
Following surgery and adjuvant therapy for glioblas-
toma, recurrence usually ensues in months (75). Opera-
tion for recurrence is increasingly being performed.
Though 90 percent of recurrent tumors will be at the site
of the original tumor, effects caused by bilateral and
deep invasive spread rather than mass effect are usually
observed at the time of recurrence (76). More authors are
describing reoperations for recurrent glioblastoma and
the number of patients undergoing reoperation are be-
coming a greater percentage of the total number of pa-
tients having an operation. Unfortunately, there are in-
creasing numbers of reports of patients developing
dissemination of the tumor at the time of recurrence
(77). This is especially true of patients living longer after
multimodality therapy including surgery, conventional
radiotherapy, interstitial radiation therapy, and BCNU
chemotherapy. Thus, new forms of therapy such as in-
terstitial radiation may effectively control the tumor at
the initial site, only to be followed by dissemination of
the tumor to multicentric hemisphere or leptomeningeal
sites. Craniotomy and shunting procedures have often
been implicated in the dissemination of gliomas. Special
precautions to minimize iatrogenic metastases, includ-
ing minimal tumor manipulation and preoperative irra-
diation, will need to be considered in future treatment
protocols for patients with gliomas.
Another indication for reoperation is radiation necro-
sis secondary to whole brain or, more likely, interstitial
iiradiation. This latter form of therapy is being increas-
ingly used with definite prolongation of life, but asso-
ciated with a 40 to 50 percent incidence of radiation
necrosis. The necrosis is at times not amenable to steroid
treatment and will require reoperation if the CT or MRI
scans leave the diagnosis in doubt or if the patient's con-
dition deteriorates from mass lesion effect.
Ransohoff and Lieberman have defined the major cri-
teria for reoperation following recurrence (78). Essen-
tially, the recurrence should be causing neurological
symptoms and deficits because of mass effect, the recur-
rence should be in a polar location, and the patient
should have had six good clinical months since the origi-
nal operation. Recently, Arnrnirati and Harsh with their
associates published a series of patients with anaplastic
gliomas and glioblastomas with a median survival of 36
weeks after reoperation (79,80). Patients undergoing ex-
tensive resection with preoperative Karnofsky ratings of
70 or better have the best chance of benefitting from
reoperation.
Recurrence of a glioma after operation or chemother-
apy may be associated with a cyst. Poisson and co-
workers found a 5 to 8 percent incidence of cystic glio-
mas, and Afra, Norman, and Levin estimated the true
absolute incidence to be 8 to 10 percent in recurrent
malignant gliomas (81,82). In four patients with cystic
recurrence of tumor reported by Levin and associates,
the cyst was accompanied by clinical signs of acutely
increased ICP and aspiration produced prompt re-
lief (83).
Sequential CT or MRI scanning is useful to detect the
positive effect of a treatment plan in clinically stable pa-
tients, nonturnor—related causes of clinical deterioration,
early treatment failure as a prelude to reoperation and/or
change in drug protocol, and complications of the treat-
ment plan such as the 20 percent incidence of ventricu-
lar enlargement (84).
Metastasis
There have been only 72 cases reported of metastases
of astrocytornas and glioblastomas, with extraneural ine-

tastasis most commonly occurring in adults. The rnetas-
tases were pulmonary and pleural. Only eight cases devel-
oped without a previous craniotomy, and in another
eight, the extraneural metastasis developed via a sys-
temic shunt (85-87). The reasons for the rarity of this
event are undefined at present. Explanations include the
brief survival of most of these patients, the absence of
lymphatics in the central nervous system (CNS), the lack
of access of the tumor cells to the venous system, and a
systemic immune response that prevents the implanta-
tion of tumor cells in the periphery. The fact that most of
these patients with extra-CNS metastases had undergone
prior operation indicates that the entrance of tumor cells
into the vascular system is an important precursor of
spread outside the CNS (88). Morley has demonstrated
tumor cells in the jugular vein during craniotomy and
probably, as patients live longer, astrocytomas and glio-
blastornas will no longer be considered local diseases of
the brain (89).
Cerebellar Astrocytomas of Childhood
P»:
Incidence
Cerebellar astrocytomas of childhood are regarded as
the least malignant ofall gliomas (67). They are the most
common infratentorial tumor in children, with an inci-
dence of 48 percent in Matson's series of brain tumors in
childhood (90). This tumor occurs predominantly in the
first tWo decades of life.
Symptoms and Signs
The symptoms and signs may be those of increased
intracranial pressure from hydrocephalus or lateral cere-
bellar signs with unilateral motor and cranial nerve defi-
cits, particularly lirnb ataxia. There may be morning
vomiting, irritability and headache, as in a patient with a
medulloblastoma.
The examination usually reveals papilledema, nystag-
rnus, and cranial nerve palsies, especially of the sixth and
seventh cranial nerves. Dysmetria of the ipsilateral limbs
is usually present and the patient has a tendency to fall to
the side of the tumor.
Pathology
It is possible to distinguish between two groups of
childhood Cerebellar astrocytomas: (1) juvenile astrocy-
tomas, according to the classiﬁcation of Russell and Ru-
binstein, and (2) a group morphologically resembling ce-
rebral astrocytornas, with a poorer long—term prognosis.
Both may be cystic.
Russell and Rubinstein actually divided childhood
BRAIN TUMORS 123
cerebellar astrocytomas into three types: (1) a juvenile
pilocystic type; (2) a juvenile pilocystic type having bun-
dles of glial fibrils separated by spongy areas; and (3) a
diffuse astrocytoma indistinguishable from cerebral as-
trocytomas (1). About 15 percent of cerebellar astrocyto-
mas belong to the latter type. Both in vitro and in vivo
biological differences exist between the two general
types—juvenile and diffuse—of cerebellar tumors. In
particular, bipolar cells are characteristic of the juvenile
astrocytoma; these are preserved during tissue culture
and in transplants (91,92).
Diagnostic S tadies
Skull x—rays may show signs of increased ICP. CT or
MRI is of great diagnostic value as it will show a cystic
lesion in a cerebellar hemisphere or in the midline ver-
mis (Fig. 4). Enhanced MRI appears to show the margin
of these tumors very distinctly and, in our experience,
these margins correspond closely with the extent of tu-
mor found at operation.
Operation
Either a midline bilateral craniectomy with removal of
the arch of the atlas or a paramedian approach with uni-
lateral craniectomy can be employed to gain exposure
for cortical incision or needle aspiration. If cystic, the
cyst is drained and the cyst wall mural nodule is found
and removed. It is not necessary to remove the cyst wall.
as this is compressed brain tissue. This is often a most
gratifying procedure and results in relief of symptoms
from increased intracranial pressure and of local cerebel-
lar signs and symptoms. Solid astrocytomas cannot be
completely removed if they invade the brainstem, and
the operation must be confined to removal of the exo-
phytic portion of the tumor. The C0; laser is very useful
in evaporating the tumor from the brainstem.
Outcome
Early recurrence is rare after gross total excision. In
general, if there are no new symptoms four to five years
after surgery, one can be optimistic about a cure (93).
However, recurrences leading to death have been re-
ported 20 and 23 years after gross total removal (94),
suggesting the need for longer follow-up studies. Kuhlen-
dahl, Stochdorph, and Hubner found that 8 of their 70
patients with a cerebellar astrocytoma had an astrocy-
toma histologically identical to a cerebral astrocytoma;
all eight patients died within two to four years following
surgery (95).
In a report by Gj erris and Klinhen on cerebellar astro-
cytomas found in 10- to 14-year-old children (93), 70

124 / CHAPTERS
FIG. -4. (A) Sagittal MRI of cystic astrocytoma of vermis of the cerebellum; (B) gadolinium enhanced
axial MRI demarcating the tumor well and aiding in total tumor removal at operation.
percent were juvenile astrocytomas while 30 percent
were diffuse astrocytomas. For children with the juvenile
type of cerebellar astrocytoma, the 25-year cumulative
survival rate was 94 percent, compared with 38 percent
for children with the diffuse type. In the SEER registry,
the 5-year survival of 110 children with cerebellar astro-
cytoma was 91 percent (96).
Brainstern Gliornas
Incidence
Brainstern gliomas tend to occur during childhood
and adolescence. Russell and Rubinstein reported that
77 percent oftheir patients with a brainstem tumor were
under the age of 20 years, and they noted that brainstem
gliomas comprise a significant portion of the brain tu-
mors of children (1). Brainstern gliomas accounted for
18.7 percent of posterior fossa tumors in Matson's series
(90). At the Hospital for Sick Children in Toronto,
brainstem gliomas comprised 16.1 percent of all brain
tumors and 28.7 percent of all tumors found in the infra-
tentorial region (97).
Symptoms and Signs
These children usually present with cranial nerve pal-
sies, weakness of the arms or legs, sensory changes, and
difficulty with gait. Headache or any symptom of in-
creased ICP is rare.
The examination generally reveals multiple bilateral
cranial nerve palsies, usually involving the sixth and sev-
enth nerves; intranuclear corticospinal tract signs; and
ophthalmoplegia with hyperactive reﬂexes with Babinski
toe signs. The signs are usually bilateral, but not syrrnnet—
rical. Papilledema is usually not found as hydrocephalus
does not occur early in these tumors.
Pathology
The vast majority of brainstem gliomas originate in
the pons and extend cephalad and caudad for a distance.
This produces a diffuse enlargement of the brainstem. In
the early phase of tumor growth, the tumor infiltrates
between normal neural structures, separating but proba-
bly not destroying them. The cells of brainstem gliomas
are very similar to those of diffuse fibrillary astrocytomas
of the cerebral hemispheres. They may undergo anaplas—
tic changes. Russell and Rubinstein reported that 62.8
percent ofthese tumors in their series showed changes in
keeping with glioblastoma multiforme (1).
Hoffman, Becker, and Craven have reported a small
group of these tumors that have a distinct biological be-
havior (97). The syrnptorns in this group begin in early
childhood or even in infancy and the history is usually
long. These tumors fill the fourth ventricle, may extend
up into the cerebellopontine angles, and may mushroom
down over the dorsal surface of the cervical spinal cord.
Pool reported on three patients who had a partially cystic
or nodular infiltrating brainstem glioma that responded
favorably to operative decompression and irradia-
tion (98).
Diagnostic Studies
Patients with brainstem gliomas deserve the most criti-
cal diagnostic studies. A properly performed CT or MRI

scan may prevent unnecessary posterior fossa opera-
tions. In all cases of brainstem gliomas, the brainstem
appears widened on CT or MRI, and the fourth ventricle
will be abnormal. Most often, the fourth ventricle ap-
pears ﬂattened, with an apparent increase in its trans-
verse diameter, and will be displaced posteriorly. CT sec-
tions thinner than 13 mm are often required to
demonstrate the ﬂattened fourth ventricle (99). Attenua-
tion profiles for brainstem tumors are variable and of no
value for diagnosis, although the most malignant tumors
are believed to show the greater enhancement. The tu-
mor may be of low density and not enhance, low density
with enhancement, isodense without enhancement,
mixed density with enhancement, or increased density
with enhancement. Tumors with increased density,
which appear to fungate into the fourth ventricle or sub-
arachnoid cisterns and enhance strongly with a contrast
agent, are the only lesions that should be considered for
open operation (craniotomy).
Patients who have an enlarged brainstem on MRI or
CT scan, without tumor extension into the ventricle or
subaraclmoid spaces, should not require an open opera-
tion. The radiologic study ofchoice for children and ado-
lescents with hydrocephalus should be MRI, including
axial and sagittal T1. and T2—weighted images (100).
Operation
In 1968, Pool strongly suggested that any patient sus-
pected of harboring a brainstem glioma should have an
operation (98). If, following exposure of the brainstem, a
biopsy does not appear to be a safe undertaking, a visual
inspection may nevertheless be helpful in confirming the
diagnosis. An enlarged brainstem with elevation of the
ﬂoor of the fourth ventricle, but without exophytic tu-
mor rnass, should be viewed as strong evidence for a
brainstem tumor. If there is any evidence by contrast
study of a cyst, stereotactic needle aspiration can be at-
tempted (101-103).
Fortunately, since Pool's 1968 report, CT and MRI
scanning has enabled clinicians to make a more certain
diagnosis prior to operation. Not only will the scan show
the enlarged brainstem as was previously visualized only
on pneumoencephalography, but an enhancing exo-
phytic mass may be seen. As emphasized by Hoffman,
this mass, especially if found in a child with a long clini-
cal history, should undergo surgical resection. At opera-
tion, the solid part of the mass that fungates out of the
dorsal aspect of the brainstem can be safely removed by
microsurgical techniques. Usually, a small portion ofthe
tumor must be left in the ﬂoor of the fourth ventricle and
in the medulla (97).
BRAIN TUMORS / 125
Outcome
In the past, survival for longer than one year was so
uncommon that Matson stated that if a patient was stil
alive 18 months after diagnosis, reinvestigation and sur-
gical exploration was indicated, as sorne other lesion was
probably present (90). Even today, intrinsic gliomas of
the brainstem have a bad prognosis, and most children
with such tumors have a median survival of less than one
year in most studies, regardless of therapy. In Hoffman
and associates‘ series of 111 cases, 51 were verified histo-
logically and 32 (62%) of these were Grade III or IV
astrocytomas (97). In this series, there were 10 patients
(8.3%) who had clinical evidence of increased intracra—
nial pressure. Of the 10 patients, 5 had hydrocephalus.
and 5 presented before the age of two with a history of
vomiting and failure to thrive. Of these 10 patients in
Hoffman's series/ 8 had long—term survival, with the lon-
gest survivor alrve 15 years after treatment. Thus, the
clinician should, be aggressive and make every attempt to
treat this subgroup successfully by subtotal surgical exci-
sion and radiotherapy. There are some recent reports of
benefit from combination chemotherapy with 5—ﬂu—
orouracil, l—(2—chlorethyl)—3—cyclohexyl—l—nitrosurea
(CCNU). hydroxyurea, and 6—mercaptopurine for recur-
rent brainstem gliomas (104-106).
Optic Nerve Gliomas
Incidence
Optic nerve gliomas comprise 1.7 percent of all intra-
cranial gliomas (107) and up to 7 percent of gliomas in
children (108). They are actually slowly growing, non-
metastasizing neoplasms of the anterior visual pathway.
Seventy—f1ve percent of optic nerve gliomas occur in the
first decade and 90 percent occur in the first two decades
of life, with equal sex distribution (109). These tumors
are present in 1 of 100,000 patients with eye symptoms.
Symptoms and Signs
The clinical presentation depends on whether the tu-
mor is in the orbit or is located intracranially. Intraorbi—
tal gliomas present with painless proptosis, which may
be the only sign, especially in infants. The most common
initial symptom is loss of vision. Bilateral blindness is
unusual, even in advanced cases. In children, visual loss
may present as strabismus or nystagmus. The visual field
defects are variable and nonspecific. Some patients have
scotoma of the central field, but peripheral field defects
are also common. The defects may be dense or mild,
quadrantic, hemianoptic, or irregular. There may be ab-

126 / CHAPTERS
sence of biteinporal hemianopia even when the chiasm is
involved.
Pathology
The pathology of optic nerve gliomas is the subject of
continuing controversy. There is now general agreement
that the optic nerve glioma is an astrocytoma and many
of these tumors, especially in children, have a slow be-
nign biological course. Currently, most authors use the
term "pilocystic astrocytoma of the juvenile type" and
compare the biological behavior of optic gliomas to pilo-
cystic astrocytomas in other parts of the ncuraxis
(110,111). The association of optic nerve gliomas with
neurofibromatosis has been noted at least since 1893.
The relationship between von Recklinghausen's disease
and optic nerve tumors has long been known, and by
1954 approximately 500 cases of glioma of the optic
nerve and chiasm had been reported in the literature,
with 22 percent (108 cases) associated with von Reck-
linghausen's disease. Now the generally accepted inci-
dence of optic nerve glioma in association with neurofi-
bromatosis is approximately 25 percent (112). These
tumors may be multicentric, originating in more than
one locus, or may spread through the chiasm to involve
the opposite optic nerve. No doubt these tumors will be
found more frequently with the increasing use of CT and
MRI scans.
In a series of 84 patients with gliomas involving the
chiasm, only 7 percent had neurofibromatosis and 70
percent ofpatients with gliomas involving only one optic
nerve had neurofibromatosis (112). Multicentric glio-
mas are frequently associated with neurofibromatosis.
The association with neurofibromatosis doubles the re-
currence rate following the complete excision of an in-
traorbital glioma but does not affect the prognosis follow-
ing irradiation of chiasmal gliomas (113).
A highly malignant optic nerve glioma does occur in
adults and rapidly infiltrates the chiasm and hypothala-
mus, Causing death.
Diagnostic Studies
CT and MRI scans are especially useful for intraorbi—
tal pathology and will nearly always document an optic
nerve glioma. This is generally revealed as an enlarged
optic nerve in comparison with the optic nerve of the
normal eye (114). A CT and/or MRI scan should differ-
entiate a glioma of the optic chiasm from a craniopha—
ryngioina by the sharp outline of the craniopharyn—
gioina, which is often cystic and calciﬁed (115). \
Plain skull x—rays should always include views of the
optic foramen. The optic foramen and canal will usually
be enlarged on the side of the tumor.
Operation
Neurosurgeons generally approach the optic nerve
and chiasm by a frontal craniotomy approach over the
orbital roof. The latter can be opened when necessary
and intraorbital contents exposed to remove an optic
nerve tumor. If the tumor is confined to one optic nerve
by clinical examination and radiological studies, opera-
tion for total removal is advised. If at operation the tu-
mor is verified to be confined to one optic nerve, total
excision of the nerve is indicated.
The glioma that invades the optic chiasm or hypothala-
inus is impossible to completely remove. A biopsy
should be done at operation to rule out a craniopharyn—
gioina, which can displace and stretch the optic chiasm,
giving the appearance of an infiltrating neoplasm. A spi-
nal ﬂuid shunt is indicated if the spinal ﬂuid pathways
are blocked.
Outcome
The reports of Oxenhandler and Sayers, as well as Al-
vord and Lofton, confirm these lesions to be neoplasms
and not hamartomas as suggested by Hoyt (116-118).
Therefore, total excision should be done for unilateral
optic nerve gliomas, especially when there is severe vi-
sual loss or blindness. Prognosis for survival is excellent
(116,119,120). Surgical excision is better than irradia-
tion to prevent recurrence of optic nerve gliomas but of
course does not preserve vision (121). About 25 percent
of optic nerve gliomas have already invaded the optic
chiasm at the time of diagnosis and another 5 percent
recur in the chiasm following "complete" intraorbital
excision. There is a stepwise effect of age on outcome,
with an increasing probability of death from tumor
above the age of 20 years, especially obvious in patients
over 50 years of age, half of whom have glioblastoma
multiforme (117).
Ependymomas
Incidence
Ependymomas had an incidence of 1.9 percent of
3,878 histologically verified neoplasms involving the
central nervous system and 3.4 percent of 2,186 gliomas
at the Montreal Neurological Institute during the period
1928 to 1964 (122). In this series, 47 patients had intra-
cranial ependymomas; 64 percent were female. The
average age at admission was 22 years, ranging from a
7—month—old male with a fourth ventricle ependymoma
to a 64-year-old male with a tumor in a similar location.
Posterior, fossa ependymomas are seen more frequently

in children than are supratentorial ependymomas but
represent only 1 percent of tumors in the posterior fossa
in this age group (123). Supratentorial ependymomas
are usually present in the cerebral substance rather than
in the ventricular system (124).
Symptoms and Signs
Headaches are the most frequent complaint, probably
related to obstruction of the fourth ventricle. Vomiting
with the headaches is common. Diplopia, decreased vi-
sion, dizziness, ataxia, or extremity weakness are ob-
served at times. In a young child, the associated hydro-
cephalus may cause the head to enlarge. If there is
herniation of the cerebellar tonsils, cervical pain or stiff-
ness may be present.
Pathology
Although the ependyrnornas have been subclassiﬁed,
the histological grade of the tumor does not appear irn—
portant in prognosis (123). There is, however, a clearly
malignant form—the ependymoblastoma (125). The
ependymoblastoma is a highly cellular, embryonal tu-
mor occurring in children, with a notably poor prognosis
and a tendency to subarachnoid spread. The rnyxopapil—
lary type is generally considered to be intraspinal. The
prognosis of malignant ependymomas is highly variable
but 67 percent of the patients reviewed by Ross and Ru-
binstein had a survival time of 8.8 years (126).
Diagnostic Studies
Plain skull x—rays may show intracranial calcification,
especially with intraventricular ependymomas. If hydro-
cephalus develops there may be separation of the cranial
sutures, particularly in young children. The principal an-
giographic findings are nonspecific, with avascular
masses usually observed although focal tumor vascular-
ity is found in a minority of cases. Sixty percent of epen-
dyrnornas of the posterior fossa are associated with sub-
arachnoid extension of the tumor into the cisterna
magna and sometimes into the cervical subarachnoid
space, a point in the differential diagnosis of an ependy-
moma from a rnedulloblastorna on CT or MRI scan.
Operation
Surgery for an ependymoma should be as radical as
possible but should not proceed if an attempt to remove
the tumor would be likely to damage the brainstem (Fig.
5). Pierluca has noted that, at autopsy, recurrences are
BRAIN TUMOKS ° 127
RG. 5. Ependyrnoma of the fourth ventricle appeared cir-
cumscribed on surface but had a firm infittrating attachment
to the brainstem, making total removal by operation impossi-
ble.
not usually found at the site of tumor remaining in the
brainstem but rather in the cerebellum (127).
Outcome
In the series from the Montreal Neurological Institute,
there was a much poorer prognosis in the younger age
groups, primarily because of the dominant location of
the tumor in the fourth ventricle (122). Of the patients
over 15 years of age, 38.3 percent survived 5 years or
longer following surgery, whereas only 19.1 percent
under 15 years of age survived for the same period. Aver-
age postoperative survival as of 1965 for 7 patients with
grossly complete removal of tumor was 20 years. Hahn,
Shapiro, and Okawara also reported an especially poor
prognosis in patients less than 10 years of age (124). In
the review by Pierluca, the overall survival rate was 33
percent. Of the 25 who died during a period of 8 months
to 17 years postoperatively, the average time of recur-
rence was 2 years, and the average survival time was only
2j years (127).

128 / CHAPTERS
When tumor remains in the brainstem following oper-
ation or is clearly a malignant ependymoblastoma, irra-
diation of the tumor site is urged. Irradiation of the spi-
nal areas is not usually necessaiy. In the series from the
Montreal Neurological Institute, there were no instances
of spinal seeding (122), but there were cases of tumor
nodules involving the cauda equina in the series of 70
ependymomas of the ﬂoor of the fourth ventricle in the
series reported by Pierluca (127).
Oligodendrogliomas
Incidence
Among the glioinas, the oligodendroglioma deserves
special attention. These tumors are reported to represent
between 3 and 7 percent of primary brain tumors (128).
They occur primarily in the third and fourth decades of
life and are found primarily in the frontal lobes.
Symptoms and Signs
The patient with an oligodendroglioma usually has a
long history of headaches or seizures which relate to the
location of the tumor. Since Oligodendrogliomas fre-
quently involve the frontal lobes, personality changes are
common as well. Also, some of these tumors grow along
the walls of the ventricle and may reach the aqueduct or
even the fourth ventricle, causing obstruction of CSF
ﬂow and hydrocephalus. Papilledema is the most coin-
mon neurological finding.
Pathology
The oligodendroglioma was described and reported
initially by Bailey and Gushing in 1926 (129). Grossly,
the oligodendroglioma may present by expanding the
cortex or be observed to break through the cortex and
.attach to the meninges. The tumor is red—gray, is gener-
ally firm, and may contain cysts with small necrotic foci.
When cut, the tumor often has areas of gritty calciﬁca-
tion.
Microscopically, the tumor has been classified into
isomorphic and pleomorphic types, which is of clinical
significance. The isomorphic type is extremely cellular
and uniform in appearance. The cells are closely packed
like cobblestones, each individually "boxed in" by capil-
laries or connective tissue. The cells have regular central
nuclei and clear cytoplasm. The pleomorphic tumors are
much more anaplastic, with increased mitotic ﬁgures,
pleomorphic nuclei, focal necrosis, and endothelial vas-
cular changes. This rnore hetero genous appearance corre-
lates with a much more rapid clinical couise.
Oligodendrogliomas are often "mixed" tumors, con-
taining areas of other glial differentiation. Russell esti-
mated that half of all Oligodendrogliomas contain some
component of a second tumor type, the significance of
which is unknown (1). It would seem that more Oligo-
dendrogliomas contain an anaplastic astrocytic cornpo—
nent than do not. Smith and associates devised a grading
system for Oligodendrogliomas, classifying the tumors
from A through D. They demonstrated a worse progno-
sis for higher—grade tumors (130). Others have not found
this classification system to be prognostically useful
(131,132).
Diagnostic Studies
Up to 65 percent of well—differentiated Oligodendro-
gliomas will exhibit stipplid calcification on plain skull
x—ray. This is the highest percentage of calcification
among all gliomas. Calcification is also highly visible on
the CT scan, which usually localizes the tumor well.
These tumors enhance with contrast and are usually
surrounded by mild to moderate edema. A cystic cornpo—
nent may be found as well.
Operation
The principles of operation for Oligodendrogliomas
are the same as those for astrocytomas of the cerebrum.
As much tumor as possible should be removed, leaving
the least tumor burden without increasing neurological
deﬁcits. At times, the tumor may appear partially cir-
cumscribed and, with the aid of the microscope, can be
readily removed. Deep tumor involving the peri ventricu-
lar areas is, however, difficult to remove, as there is often
no cleavage plane between tumor and normal tissue.
Outcome
Weir and Elvidge, as well as Zulch and Wechsler, 1e-
ported that the postoperative survival of patients with an
isomorphic oligodendroglioma was almost twice as long
as that of patients with a pleomorphic tumor (108,133).
Survival was also longer in those patients who had com-
plete removal than in those who had incomplete re-
moval. Though soine authors have stated that there is as
yet no proven value of radiation therapy in patients with
Oligodendrogliomas, others strongly point to a beneficial
effect from radiation therapy (131).
The 10-year survival rate for 14 patients with an iso-
morphic oligodendroglioma who received greater than
45 Gy irradiation was 56 percent, versus 18 percent for
11 patients who did not receive postoperative irradiation
(134). In a report by Richmond and McKissock on the

pleomorphic tumor, no patient survived five years even
when operation was followed by irradiation (135). Thus,
the treatment of choice is radical removal with radiation
therapy (136). The patient with a pleomorphic oligode1r—
drogliorna should have chemotherapy as well, although
no controlled prospective studies have been reported.
Some patients respond well to BCNU. Oligodendrogli—
oma with metastasis outside the CNS is extremely rare
and, as of 1981, only 12 cases have been documented in
the literature (137).
Medulloblastomas
Incidence
The medulloblastoma is a tumor found almost exclu-
sively irr children. This tumor represents 15 to 25 percent
of all primary intracranial tumors in children under 16
years of age, but only 1 percent or less of primary brain
tumors in adults. In the SEER Registry, rnedulloblas—
torna slightly exceeds the incidence of low—grade supra-
terrtorial astrocytomas in children, 25 percent versus 23
percent, respectively (96). Eighty percent of all cases of
medulloblastomas occur before the age of 16 and twice
as often in males as in females (138). This fact, plus the
knowledge that not only are CNS metastases common
but extracrarrial spread occurs to bone, lymph nodes,
testes, skin, pancreas, kidney, liver, intestines, ureter,
and ovaries without predisposing factors such as surgery,
survival, extensive subarachnoid spread, or radiation
therapy, makes the treatment of this tumor a special
challenge (139-142). Eighty percent of adult cases occur
between the age of21 and 40 years; by 1979 only 13 cases
had been reported presenting after 50 years of age (143).
Symptoms and Signs
Patients with a medulloblastoma usually present with
some variation of the clinical triad of headache, vornit—
ing, and ataxia. Because most medulloblastomas de-
velop irr the vermis of the cerebellum and, less often, in
the cerebellar hemispheres, the patient usually presents
with midline cerebellar signs. Children frequently have
morning projectile vomiting without nausea, secondary
to obstructive hydrocephalus. This vomiting may be
transient or disappear for several weeks before returning
with frank cerebellar signs. The child will gradually be-
come ataxic and fall or stumble more than previously
and finally will develop truncal ataxia. As the tumor in-
vades the cerebellum, localizing symptoms such as loss
of coordination will develop. As the brainstem is in-
volved by direct or indirect pressure or invasion, there
will be lo1rg—tract signs and cranial nerve deficits. In
BRAIN TUMORS 129
young children, the head may enlarge from bydro—
cephalus.
The examination will reveal signs of intracranial hy-
pertension such as papilledema and bilateral sixth nerve
palsies. Other cranial nerve deficits, particularly seventh
nerve palsies, may be present. Gait and truncal ataxia is
usually prominent, and nystagmus with lateralizing dys-
rnetria of the arm and leg may be found. Frequently,
there is hypotonia of the limbs, but hyperreﬂexia and
Babinski signs are observed as well.
Pathology
Neuropathologists have long recognized the capacity
of cerebellar medulloblastomas to differentiate. In 1925,
Bailey and Gushing considered the medulloblastoma to
be a tumor with the potential to develop along spo1rgio—
blastic or neuroblastic lines (37). In 1934, Stevenson and
Echlin proposed that the medulloblastoma arises in the
fetal external granular layer of Obersteiner (144).
Pahner, Kasselberg, and Natsky have identified glial fi-
brillary astrocytic protein (GFAP) in 11 of 13 cases of
medulloblastoma (145). They conclude that rnedullo—
blastorna is a stern—cell neoplasm with multiple types of
differentiation. In 1983. Rorke proposed a new classiﬁca-
tion system for primitive neuroectodermal tumors.
(PNETs)ofwhichthernedulloblastornaisthernostcorn—
rno1r(146).Underthissystem.PNETsareseparetedi1rto
five groups based on cell differentiation: { 1) glial, (2) 1reu—
ronal, (3) ependymal, (4) multipotential. or (5) without
differentiation. Some authors have found that the degree
of cell differentiation correlates with a significantly pro-
longed recurrence—free period and improved 5-year sur-
vival, but necrosis is associated with a decreased survival
time (147,148).
Diagnostic Studies
Plain skull x—rays in young children may reveal signs
of intracranial hypertension, such as sprung cranial su-
tures which carr occur up to the sixth or seventh year
of age.
The CT or MRI scan will show a well—circumscribed
midline enhancing lesion, usually of large size, and any
associated hydrocephalus. This is usually diagnostic for
medulloblastoma but it should be recalled that contrast
uptake in a cerebellar arteriovenous anomaly, particu-
larly in children, may simulate a tumor (149).
Medulloblastomas are slightly hyperdense, with mean
attenuation values nearly 10 Hounsfield (EMI) units
higher than those of astrocytomas (150). Mean posten—
hancement attenuation levels are significantly above
those of astrocytomas. Medulloblastomas are sur-

130 / CHAPTERS
rounded by zones of moderately decreased density, the
outer border of which is not as sharp as in astrocy—
tornas.
Operation and Postoperative Therapy
The therapy for a child with a medulloblastoma re-
mains a challenge. This rapidly growing tumor is often
localized and attached to vital structures and has a well-
recognized tendency to seed within the CNS, especially
within the spinal canal. Microimplants or metastases
have been described as being found at the original opera-
tion (151), though other authors claim CNS spread is the
result of the original operation itself (1). This spread pre-
cludes cure by operation alone. In Cushing's series of
cases treated by operation alone, the maximum survival
was 21 months and averaged 7 months (152).
The current best treatment for medulloblastomas in-
cludes surgery, irradiation, and polychemotherapy
(153). A secondary temporary or permanent spinal ﬂuid
shunting procedure may be indicated to control hydro-
cephalus caused by the tumor (154,155).
Operation on the tumor is indicated to conclusively
establish the diagnosis. CT or MRI scanning may not
definitely differentiate a medulloblastoma from an epen—
dyrnorna (150). Moreover, surgery will reduce tumor
burden, leaving less mass for radiotherapy and chemo-
therapy. The goal of the operation should be to perform
gross total tumor removal without increasing neurologi-
cal defrcits (156). The operation usually requires split-
ting the midline verrnis, but this is usually done without
neurologic sequelae. Once the verrnis is split, the tumor
is easily seen as a reddish—purple mass that can be re-
moved by suction—aspiration. Intraoperative magnifica-
tion of the tissue interface will allow differentiation of
tumor from brain, as the tumor may well inﬁltrate into
the cerebral peduncles, cerebellar hemispheres, and ﬂoor
of the fourth ventricle. No damage must occur to these
vital structures, as the resultant postoperative ataxia and
loss of coordination would be incompatible with normal
gait or even independent ambulation.
Radiotherapy has been used since 1919 in the treat-
ment of patients with a medulloblastoma. In 1930,
Gushing reported on the first case of whole CNS irradia-
tion for a medulloblastoma (152). Irradiation to the en-
tire central nervous system, including the supraorbital
cranium and brain, using modern equipment and dosirn—
etry, can achieve a disease—free interval of five years in 50
to 60 percent of patients. Radiation treatment of the
craniospinal axis (CSA) is technically exacting and re-
quires painstaking attention to detail. Modern radiother-
apy has substantially improved the prognosis for patients
with a medulloblastoma. However, the best outcome
that can be achieved with conventional radiation ther-
apy alone is limited by CNS tolerance levels and proba-
bly has been achieved.
Unfortunately, radiotherapy, although offering a po-
tential for cure, also produces profound late side effects
that are detrimental to the patient, as well as limiting the
potential of other therapies. Though the importance of
x—ray therapy in this tumor cannot be overstated, cer-
tainly the complications should not be underempha—
sized. The size of the target dose is not settled, but Land-
berg and coworkers suggest an absorbed dose of 45 Gy in
not more than 30 fractions over six weeks to the demon-
strated tumor, and 30 Gy in 20 fractions over four weeks
to the subdural space (157). This dosage is well below the
threshold value for serious CNS reactions of 50 Gy in 45
days as reported by Lindgren (104). Using the high de-
gree of precision as outlined above, Landberg and asso-
ciates projected their 10-year survival to b& 53 percent.
Unfortunately, homogenous field radiotherapy has
failed to prevent recurrence of medulloblastoma (158).
For subclinical disease, Ieibel and Sheline, at trie Univer-
sity of California, San Francisco, recommend doses from
3,500 to 4,500 rads for the brain, and 3,000 to 4,000 rads
for the spinal cord (159). Additional irradiation can be
given to sites shown by pretreatment scans or myelo—
grarns to be involved. The posterior fossa dose is rou-
tinely boosted through opposed lateral fields to a total
dose of about 5,500 rads. The desg is reduced by approxi-
mately 1,000 rads in children of lessThan 2 years of age.
Adj uv ant chemotherapy should also be given to patients
with medulloblastoma, at the time of bone marrow re-
covery and before asymptomatic recurrences occur. We
favor this because operation plus irradiation cures about
50 percent of these patients, leaving an equal number
who will suffer recurrences.
Among the most promising protocols advanced thus
far is that published by Venes and associates (160). Al-
though administered to only a small series of children
with a biopsy—proven medulloblastoma, whole neuraxis
radiation was followed by prolonged chemotherapy us-
ing vincristine and cyclophosphamide. The patients re-
ceived intravenous vincristine sulfate (1.5 rng/sq m) alter-
nating weekly with cyclophosphamide (300 gm/sq m) by
mouth. Both vincristine sulfate and cyclophosphamide
have been reported to produce prolonged remission of
the central signs and symptoms of recurrent rnedulloblas—
torna. Combination therapy with these two agents has
been shown to be effective in the control of childhood
neuroblastoma, a tumor that hi stologically resembles ine-
dulloblastorna. The vinca alkaloids are cell—cycle—spe—
ciﬁc agents and block mitosis with metaphase arrest. Cy-
clophosphamide is a nitrogen mustard belonging to the
class of alkylating agents. This agent is not cell—cycle—spe—
cific and may act on cells at any stage of the cycle. With
this combination of agents for a period of two years, with
modification of dosage when toxic side effects occurred,

Venes and coworkers repoited no evidence of tumor re-
currence in the follow—up period, which ranged from 16
months to over 7 years.
The use of adjunctive polychemotherapy in cerebellar
medulloblastomas is logical. Duration of therapy at pres-
ent remains empirical. The recurrence rate for medullo-
blastoma appears to peak in the first two years and is
associated with a high percentage of deaths during this
period (161,162). Thus, the use of chemotherapy follow-
ing surgery and irradiation, during the period of aggres-
sive tumor recurrence and before onset of a large tumor
burden, appears to offer the best chance for immediate
and long—term control of medulloblastoma.
Reports of late chemotherapy for recurrent medullo-
blastoma, failing to obtain a long—term remission and
much less a cure, add further support to the concept of
[initial adjuvant chemotherapy for medulloblastoma. In
the report of Crafts and coworkers, 17 patients with re-
current medulloblastoma were treated with a combina-
tion of three drugs: procarbazine, CCNU, and vincris—
tine (163). Significant rnyelotoxicity, exacerbated by
prior irradiation, compromised therapy. After an initial
response, it was often necessary to reduce the high doses
of CCNU and procarbazine because ofbone marrow tox-
icity. Although 10 patients showed an initial response,
on the basis of neurological improvement and decrease
in tumor size by radiological criteria, the median time to
progression was only 45 weeks, without any evidence of
a cure.
A report of Thomas and associates strongly suggested
that initial multimodality therapy for medulloblastoma
is more effective than late chemotherapy of recurrent
medulloblastoma (164). In their series, eight patients
with recurrent medulloblastoma responded to a regimen
consisting of vincristine, BCNU, dexamethasone, and in-
trathecal and intermediate dose intravenous methotrex—
ate (500 mg/m2). The median duration of response was
18.8 months. More importantly, four of nine patients
with newly diagnosed medulloblastoma, treated with the
same regimen, were well and disease—free at intervals of
up to 36 months. Intraventricular methotrexate and/or
intravenous BCNU during radiotherapy was associated
with severe toxicity, including three deaths. They recom-
mended against the use of intraventricular methotrexate
and advocated caution in the use of suppressive drugs
during the period of craniospinal radiotherapy. Al-
though this report is encouraging, we recommend with-
holding suppressive chemotherapy until there is clear re-
covery of bone marrow function following radiotherapy.
The role of chemotherapy in the treatment of medullo-
blastoma has not yet been clearly defined. The prelirni—
nary conclusions of the International Society of Pediat-
ric Oncology (165), the Children's Cancer Study Group,
and others indicate that chemotherapy may be useful in
delaying disease recurrence, but will not significantly
BRAIN TUMORS 131
prevent recurrence (166). Furthermore, chemotherapy is
most useful in young children in whom there was exten-
sive tumor invasion and incomplete resection (167). fa
one study, there was no significant increase in the recur—.
rence—free period or in the survival rate in 15 patients
receiving adjuvant chemotherapy (168).
Outcome
In general, adult and female patients with a rnedullo—
blastoma have a better prognosis. Berry and coworkers
noted the five—year survival rate t\) be 60 percent for chil-
dren over five years of age and 48 percent for those under
five years of age (169). Proper therapy now advocates
removal of as much tumor as possible, followed by radia-
tion therapy. In general, gross tumor removal has been
found to produce the best long—term survival. This tu-
mor clearly has a potential for cure (164,170—174).
Operation allows for a great reduction of tumor burden,
without producing mental changes or profound neuro-
logical deficits. Radiotherapy clearly has a role in the
therapy of this tumor. Unfortunately, there are increas-
ing numbers of reports that children who receive i1radia—
tion for intracranial tumors exhibit delayed intellectual
and even late endocrinological deﬁcits. Raimondi and
Tomita have shown a significant difference in the mental
and physical development between the rnedulloblas—
toma and cerebellar astrocytonia groups which cannot
be attributed to hydrocephalus, anxiety, supratentorial
metastasis, or absence from school (175).
Other authors have also stressed postradiation mental
and behavioral disturbances. Hirsch and colleagues re-
ported a series of 57 patients with a medulloblastoma
operated on from 1964 to 1976 (176). The functional
outcome for 11 patients surviving with rnedulloblas—
toma was compared with that for 18 patients with cere-
bellar astrocytoma; the latter patients did not receive ra-
diotherapy. Only 36 percent of the medulloblastoma
patients had a normal scholastic record, compared with
72 percent of the patients with astrocytoma and 80 per-
cent of the normal control group. An IQ level lower than
70 was seen in patients in whom the medulloblastoma
had been adherent to the brainstem. It was postulated
that the psychological deficit could be caused in part by
malfunction of the thyroid and hypothalamic structures
secondary to irradiation. Other studies have suggested a
correlation between the number of rads delivered to the
hypothalamic axis and a deficit in growth hormone. Sha-
let and associates have demonstrated particularly well
these late effects in children who received cranial irradia-
tion for the treatment of intracranial malignancies (177).
Irradiation may affect the growing spine and lead to axial
growth retardation.
Lastly, spinal ﬂuid markers, such as polyamines, may

132 / CHAPTERS
be useful in predicting the course of therapy in patients
with rnedulloblastoina (178,1791
Hemangioblastomas
Incidence
Hemangioblastomas are rare, benign, vascular tumors
that may arise anywhere in the body, and that account
for 1.0 to 2.5 percent of all intracranial neoplasms. The
most common site in the CNS is the posterior fossa, espe-
cially the cerebellum, where they comprise 7.3 to 8.8
percent of all posterior fossa tumors (181). Hernangio—
blastomas are thus the fourth most common tumor of
the posterior fossa; 80 percent of these tumors arc lo-
cated in the cerebellar hemispheres (180). They rarely
occur outside of the posterior fossa. Hemangioblastomas
occur both sporadically and as a manifestation of von
Hippcl—Lindau syndrome, characterized by tumors or
tumorlike lesions developing in several organs, including
angiomatosis of the retina (von Hippel disease). In addi-
tion to its association with angiomas of the cerebellum
and retina (originally described by Lindau and von Hip-
pel, respectively), cysts of the pancreas, kidneys, lungs,
liver, epididymis, as well as hypernephroma and
pheochromocytoma, may be present (181). In the von
Hippel—Lindau syndrome, it is rare to find two lesions
within the brain of a single individual, but the entire
spectrum of the syndrome may be found within a family
over several generations. The syndrome is inherited by
an autosomal dominant gene with 10 to 90 percent pene-
trance.
Symptoms and Signs
Patients usually have a long history of minor neurolog-
ical and psychosomatic symptoms prior to presenting
with headaches, dizziness, vomiting, and ataxia—the
usual symptoms of a posterior fossa mass. Headache is
the most common symptom. The most common present-
ing age is in the fourth decade of life, with cases rarely
presenting before puberty or after age 60. Strangely, the
lesion is not manifest at birth or in early life.
The family history is important in the diagnosis of von
Hippel—Lindau syndrome. A positive family history of
vascular tumors in a patient with the above symptoms
strongly suggests a hemangioblastoma, although cerebel-
lar hemangioblastomas more frequently occur sporadi-
cally. Rarely, the lesion may present as a subarachnoid
hemorrhage, a frequent presentation of a spinal heman-
gioblastoma.
The neurological examination most commonly re-
veals papilledema and cerebellar signs, such as horizon-
tal nystagmus, ataxia, slurred speech, and dysmetria. Ba-
binski's sign indicates involvement of the brainstem.
Ocular palsies, including abducens and facial nerve
weakness, are also common. Retinal angiomas are found
in 5 to 20 percent of patients with a cerebellar heman-
gioblastoma and von Hippel—Lindau syndrome.
Pathology
The nodule of the cystic hemangioblastoma is a well-
encapsulated ovoid mass which measures from 1 to 2.5
cm in diameter. It is formed of fir1n,\dcep red tissue that
has a hemorrhagic appearance on cross section. On l1isto—
logical examination, it is a highly vascular structure com-
posed predominantly of delicate blood—ﬁlled channels
that, in the eye, are primarily capillaries, The interstitial
cells contain nuclei, without mitosis, in abundant cyto-
plasm. The tumor may at times be confused with an
angioblastic meningioma or metastatic hypernephroma.
Exact diagnosis may require electron microscopic exa1ni—
nation that may disclose secretory granules within the
tumor cells, indicative of erythropoietin production.
Generally, collagen is a prominent feature of meningio-
rnas and is not present in hemangioblastomas (182).
About 30 percent of hemangioblastomas are solid, with-
out evidence of cyst formation. These forms are not well
demarcated from brain tissue (183).
Diagnostic Studies
A familial history of von Hippel—Lindau syndrome,
plus cerebellar symptoms and signs, will necessitate a CT
or MRI scan and a cerebral angiogram. The CT or MRI
scan will generally demonstrate a cystic lesion, with a
peripherally located contrast—enhancing mural nodule.
The vertebral arteriogram will demonstrate a large cystic
mass with a vascular nodule.
Erythrocytosis has been reported in cases of heman-
gioblastoma. Polycythemia has been reported less often.
The association of these conditions with hemangioblas-
tomas is quite uncommon.
Operation
The operation for cystic hemangioblastoma should
aim for cyst drainage and complete removal of the nod-
ule. The nodule is usually easily located and removed.
Complete removal of the nodule will ensure against re-
currences. Solid cerebral hemangioblastomas diffusely
infiltrate the brainstem and cannot be completely re-

moved. Deep puncture biopsy or subtotal removal may
result in fatal intraoperative or postoperative hemor-
rhage.
Outcome
The operative mortality rate for cystic hemangioblas—
tomas should be very low, but for solid hemangioblasto—
mas, the mortality rate approaches 25 percent. Radia-
tion therapy has generally not been effective. The
recurrence rate is about 10 percent and relates to inco1n—
plete removal of the tumor nodule (184). In von Hippel—
Lindau syndrome, hemorrhage may occur in the retinal
lesions, leading to retinal detachment and secondary
glaucoma. Treatment may require laser photocoagula—
tion and even enucleation. Genetic counseling should be
given to patients and families with von Hippel—Lindau
syndrome (185).
Papillomas of the Choroid Plexus
Incidence
Papillomas of the choroid plexus are very rare tumors
that occur in adults and children. They comprise 0.4 to
0.6 percent of all intracranial tumors and 3.9 percent of
all tumors in patients under 12 years of age (186). They
are located in those portions of the ventricles that con-
tain choroid plexus. In adults, they are found in the
fourth ventricle, whereas in children, almost 90 percent
are found in the lateral ventricles and usually are sy1np—
tomatic before the age of three years. The tumors are rare
in the third ventricle. Those in the fourth ventricle may
extend into the cerebellopontine angle. Some authors
have claimed a higher occurrence in the left lateral ven-
tricle of males, but in most reported series no ventricular
or sex dominance has been observed.
Symptoms and Signs
The symptoms of a choroid plexus papilloma depend
on the patient's age and on the location of the tumor.
Generally, the tumor produces symptoms and signs of
increased ICP. In infants and young children, choroid
plexus papillomas present with a clinical picture of hy-
drocephalus, vorniting, irritability, squint, and enlarging
head. In infants, the fontanelle is full, hyperresonance of
the skull may be present, and usually the patient cannot
adduct the eyes. Older children may develop localizing
signs, such as hemiplegia, hemianopsia, or convulsions,
as their skulls do not expand. There may be asym1netri—
cal enlargement of the ventricles. The rapid and sudden
BRAIN TUMORS 133
onset of hydrocephalus and the presence of papilledema
are two features that distinguish hydrocephalus due to a
choroid plexus papilloma from nontumor hydro-
cephalus.
Pathology
Grossly, these tumors appear pink—gray and tufted.
Some are so friable that removal can be difficult. Micro-
scopically, they are papillary with a single layer of co-
lumnar epithelium. They differ from papillary ependy—
rnoinas by the absence of mucin and glia within the
papillae and by the lack ofrosette formation and blepha—
roplasts. The pattern is monotonous, with branching fi-
brous stroina radiating from a single point. An ultrastruc—
tural study by Ghatak and McWhortner defined the
individual capillary structures to consist of an orderly
arrangement of epithelial cells, consistently juxtaposed
against a capillary and extracellular space containing
collagen and delicate cell processes (187). They con-
cluded that the fine structural details of the choroid
plexus tumor were essentially the same as those of nor-
mal choroid plexus and thus appeared ideally suited for
an active secreting function. The large size of some of
these tumors could therefore cause overproduction of
CSF and. if absorption pathways were not adequate, ven-
tricular enlargement. Leptoineningeal fibrosis may also
be an important factor in facilitating the development of
hydrocephalus.
It is generally assumed that choroid plexus papillomas
cause an over—production of CSF, as they are usually
associated with ventricular dilatation. Eisenberg and as-
sociates, using the ventricular perfusion technique,
found the CSF formation rate to be four times normal in
a five—month—old child with a choroid plexus papilloma
and hydrocephalus (188). Gudeman and coworkers re-
ported on a 3"—year—old child with bilateral choroid
plexus papillomas (189). Hypersecretion of CSF was re-
duced 50 percent after removing one tumor and, upon
removal of the second papilloma, reduction of ventricu-
lar size occurred; there was no sign of elevated ICP three
months postoperatively.
There is a rare malignant form of choroid plexus pap-
illoma. Dohiman and Collias could find only 22 well—do—
curnented examples in a 1975 report (190). This tumoris
typically located in the lateral ventricle of young chil-
dren. It can metastasize widely to remote areas of the
neuraxis, and cases of extraneural metastasis have been
reported. This tumor can be confused with cellular epen-
dyinornas, or even metastatic adenocarcinomas, the lat-
ter, however, being rare in children. Russell and Rubin-
stein, as well as Lewis, have denned the pathological
criteria for malignant choroid plexus papilloma (1,191).

134 / CHAPTERS.
When a choroid plexus papilloma shows invasion of ad-
jacent neural tissue, loss ofregular papillary architecture,
and cytological evidence of malignancy or anaplasia, it
should be regarded as a malignant tumor.
Diagnostic Studies
Both ventricular and lumbar cerebrospinal ﬂuid pro-
tein have been reported as elevated (186). Cerebrospmal
ﬂuid protein is usually not elevated in the more common
forms of hydrocephalus.
Plain x—rays of the skull usually show signs of in-
creased ICP. There is widening of sutures in infants and
young children. CT and MRI scans have replaced pneu-
moencephalography and ventriculography as the initial
diagnostic studies. The ventricle harboring the tumor is
usually larger, and there may be a shift of the ventricle
toward the opposite side. The tumors enhance with con-
trast.
An arteriogram will generally show the presence of a
hypertrophied anterior choroidal artery; possibly a "dou—
ble tumor" sign, with one tumor in the trigone and the
other within the temporal or frontal horn; tumor stain at
the trigone; asymmetrical hydrocephalus; and a shift
away from the side of the larger tumor.
Operation
Surgical considerations of lateral ventricle papilloma
include (1) asymmetrical communicating hydrocepha-
lus, (2) expansion of the tumor mass at the trigone with
occlusion and subsequent cystic transformation of either
the temporal or occipital horns, (3) extension of the tu-
mor rnass along the choroid plexus through the foramen
of Monro and into the third ventricle, with resultant ob-
struction and progressive dilatation of the lateral ventri-
cle, and (4) extension of the tumor mass through the
choroidal fissure and into the quadrigeminal cistern
from where it may enter the opposite lateral ventricle or
the posterior fossa.
Surgical considerations of fourth ventricle papilloma
are (l) the invariable presence of symmetrical obstruc-
tive hydrocephalus necessitating a spinal ﬂuid diversion
prior to or at the time of tumor removal, (2) deterrnina—
tion of tumor extension into the aqueduct, cisterna
magna, or the pontocerebellar angle, and (3) consider-
ation of the possibility of tumor invasion of the fourth
ventricle or cerebellar hemisphere.
Trigone papillomas are best removed through a tern-
poral parietal bone ﬂap that will give access to the tern-
poral pole anteroinferiorly and the angular gyrus pos-
terosuperiorly. Prior to opening the dura, the encysted
temporal horn can be drained affording immediate de-
compression of the brain. Usually, the gyri are ﬂattened
on opening the dura. A linear cerebrotomy is made
within a sulcus located behind the angular gyrus. A 3- to
4—c1n cerebrotomy will allow adequate exposure over the
surface of the tumor. The pedicle of the tumor must
always be identified ﬁrst. This line of entry of the choroid
arteries and exit of the draining veins is found along the
inferomedial surface of the tumor. The feeding branches
of the anterior choroidal artery enter the tumor at its
posteroinferior medial surface. The vascular pedicle
from the trigone may extend anteroinferiorly along the
choroidal fissure toward the hippocampus superome—
dially, along the choroidal fissure toward the terminal
sulcus and foramen of Monro. The draining veins enter
the subependymal system, penetrate the choroidal fis-
sure to enter the quadrigeminal and galenic system or
may extend downward to enter the supraculminate sys-
tem. Smaller feeding vessels may be, coagulated but
larger feeding arteries should be clipped prior to section.
It is important that the tumor not be remoyed piecemeal
or by morcellation, especially prior to identifying, isolat-
ing, clipping, and severing the pedicle. Raimondi and
Gutierrez strongly recommend every attempt at "en-
bloc" removal of these tumors, regardless of size (192).
A lateral ventricle papilloma that extends into the
third ventricle may not only require the above approach,
but also a cerebrotomy in the frontal lobe if there is lat-
eral ventricle hydrocephalus or an encysted frontal horn.
The foramen of Monro is identified and obliteration of
the perforating feeders to the tumor carried out by pro-
ceeding posteriorly from the foramen of Monro to ap-
proximately the point at which the body of the fornix
ends. After removing the tumor at the foramen of
Monro, the line of dissection can be moved from trans-
ventricular to parasagittal by retracting the frontal lobe
laterally, so as to expose the rostrum of the corpus callo-
surn. A cerebrotomy can be made through the corpus
and extended, if necessary, to the lamina terminalis as
far as the supraoptic recess.
Lateral ventricle papillomas may extend through the
choroidal fissure into the quadrigeminal cistern and con-
tralateral ventricle. They may extend into the quadri-
geminal cistern in "dumbbell fashion" on either side of
the choroidal fissure or expand as a nodule in the
quadrigeminal cistern and subsequently penetrate the
contralateral ventricle through its choroidal fissure.
Thus, the tumor compresses the quadrigeminal plate,
becomes adherent to the commissure of the fornix, and
elevates the splenium of the corpus callosurn. Passage of
CSF from the ambient cistern into the quadrigeminal
cistern is obstructed. This tumor receives its blood sup-
ply through the medial and lateral branches of the poste-
rior choroidal arteries on both sides, the quadrigeminal
arteries, and the inferior retrosplenial arteries. It drains

mainly into the galenic system, the supraculminate sys-
tem, and the anteroinedial occipital veins. This tumor
will require a bilateral temporoparietal craniotomy for
removal. Following transventricular tumor removal,
dissection of the remaining tumor is done by the para-
sagittal approach, bilaterally on either side of the falx.
The anterior choroidal arteries must be identified as they
come over or through the tela choroidia and must be
occluded and sectioned. The bridging veins must be care-
fully identified and sectioned.
Posterior fossa papillomas may require an internal-
ized or temporaiy external spinal ﬂuid shunt procedure
for several days prior to operation. These tumors estab-
lish adhesions within the entirety of the anteroinferior
medullary velum and fastigium. They may extend an-
terolaterally into the lateral recesses of the fourth ventri-
cle. They may also send digital extensions into the ﬂoor
ofthe fourth ventricle or fungate into the cerebellar hemi-
sphere. They will often grow downward, engulfing the
posterior inferior cerebellar artery, and push through the
foramen magnum into the upper cervical canal. Before
dissecting the tumor from the posteroinferior cerebellar
or the vertebral arteries, it needs to be dissected from the
nodulus and uvula of the vermis by displacing the tonsils
laterally and identifying the feeding vessels coming from
the tonsillar and vermian branches of the posterior infe-
rior cerebellar arteries. A cerebellar incision can be made
in a limbic fashion extending from the medial surface of
one tonsil over the nodulus to the medial surface of the
contralateral tonsil, exposing the tania of the fourth ven-
tricle at the calarnus scriptorius and permitting isolation
of most of the blood supply of the tumor. Most of this
blood supply is from the tonsillar and retromedullary
portion of the posterior inferior cerebellar arteries. Care
must be taken not to avulse this tumor from the ﬂoor of
the fourth ventricle, as the precentral vessels must be
occluded and transected individually.
Outcome
In 1959, Matson and Crofton reported on the results
of surgical management of children with a choroid
plexus papilloma. Seven of 16 patients developed nor-
mally after surgery (186). Raimondi and Gutierrez re-
ported on 23 patients with only 2 deaths, but 12 patients
had persistent postoperative deficits after tumor removal
(192). In 16 of these patients, the hydrocephalus per-
sisted following operation and required a shunt. In a se-
ries of 17 patients, Hawkins reported that 6 were well
following surgery and attending regular school (193).
The survival ofchildren with a malignant choroid plexus
papilloma is about 9 months; x—ray therapy is indicated,
at least to the site of the tumor.
BRAIN TUMORS 135
Pineal Tumors
Incidence
Pineal neoplasms are rare, comprising 0.4 to 1 percent
of all intracranial neoplasms (108). The incidence of pi-
neal teratomas and germinomas seems to be much
higher in Japan than elsewhere. In 1963, Araki and Mat—f
sumato, describing a series of surgical cases collected in
Japan, reported that pineal germinomas accounted for
3.9 percent of 5,714 brain tumors (194). Recently, the
report of the Brain Tu1nor\ Registry in Japan disclosed
that the incidence ofpineal germinomas was 2.1 percent
in 3,802 primary brain tumors. The reason for the higher
incidence of pineal tumors in\Japan is unknown.
Symptoms and Signs \
In Poppen and Marino's series of 45 patients with pi-
nealomas and tumors of the posterior portion of the
third ventricle, they noted three phases in the clinical
progression of these tumors (195). Headaches, with or
without vomiting, characterized the first phase. The sec-
ond phase was characterized by blurred vision, diplopia.
change in mental outlook, ataxia. dizziness, drowsiness,
and the development of the Parinaud syndrome. In the
third phase, papilledema. marked weakness, and vaiying
degrees of spasticity appeared— Pineal tumors have also
been associated with both precocious and delayed pu-
berty (196). Eye signs represent one ofthe main 1nanifes—
tations of pineal tumors. Parinaud's syndrome is consid-
ered to be a pathognomonic sign of tumors in this area of
the brain, although other pathology, such as vascular dis-
ease or hydrocephalus from aqueduct obstruction, can
cause the same syndrome. In the case of tumors, Pari-
naud's syndrome is thought to be caused by involvement
of the rostral portions of the superior colliculus. In this
syndrome, the pupils usually are largely dilated and react
poorly to light, and there is paralysis of upward gaze.
With a suprasellar germinoma, pituitary functions will
be disturbed. Some patients will show hypopituitarism,
and others will show an elevation of plasma concentra-
tions of cortisol or luteinizing hormone and follicle-
stirnulating hormone. Diabetes insipidus and visual dis-
turbances may also develop.
Pathology
Probably the most generally accepted classiﬁcation is
that proposed by Russell and Rubinstein. In this classiﬁ-
cation, the most common pineal tumor is the teratoma,
with pinealomas, gliomas, and cysts as the three rarer
types. The essence of this classification is the belief that
V

136 / CHAPTERS
the majority of the pineal tumors are really of germ—cell
origin, and that pineal tissue itselfrarely undergoes ma-
lignant change. The pineal tumor bears close resern—
blance to the serninorna of the testes and dysgerrninorna
of the ovary (1,197). In a classical communication pub-
lished in 1947, Freidrnan observed that many pineal and
suprasellar tumors histologically were identical to cer-
tain testicular and ovarian germ—cell tumors (198). He
proposed the term gerrninorna to describe them. Pineal
tumors have been reported to rnetastasize outside the
CNS, and it is particularly the gerrninorna that does so,
usually spreading initially to the lung (199). The beta
subunit of human chorionic gonadotrophins is elevated
in the plasma of these patients and is useful in diagnosis
and follow—up of these patients.
Operation
There is considerable controversy as to the correct
treatment of patients with pineal tumors. Some surgeons
favor stereotactic biopsy, treatment with a spinal ﬂuid
shunt, and radiotherapy once a tissue diagnosis is ob-
tained. Stereotactic biopsy of third ventricular tumors is
a low—risk procedure; the most common complication is
failure to obtain tissue. With modern stereotactic biopsy,
failure to obtain tissue will decrease (200). This is an
alternative technique for the surgeons not inclined to do
open biopsy or to remove the tumor.
Other surgeons favor removal of the tumor, as the ap-
proaches to the posterior third ventricle are becoming
increasingly refined. Posterior third ventricle tumors
may be approached in several ways (201,202). One ap-
proach is frorn above the tentorium along the medial
aspect of the occipital lobe or through the corpus callo-
sum. Another approach is via a suboccipital craniec—
torny, below the tentorium and over the superior cerebel-
lum. This supracerebellar, infratentorial approach is
useful for tumors of the pineal region because the galenic
venous system that caps the dorsal and lateral aspect of
pineal tumors does not obstruct access to the tumor. The
infratentorial supracerebellar approach is not well suited
for tumors with a significant extension above the tento-
rium, or that are growing from the thalamus or corpus
callosum into the third ventricle, or for lateral lesions
(203). Therefore, infratentorial supracerebellar exposure
is useful for rnidline lesions in the region of the pineal
gland, posterior third ventricle, and superior cerebellar
vermis. This approach affords easy identification of deep
structures, avoids the tributaries of the vein of Galen,
and allows the surgeon access as far as the foramen of
Monro. The medial bridging veins from the cerebellum
to the tentorium can be safely divided as the cerebellum
is separated from the tentorium, exposing the upper
midbrain and posterior third ventricle. The lower mid-
brain and anterior rnedullary velurn are seen as the up-
per verrnis is incised or retracted (204,205). The poste-
rior internal cerebral veins may surround or be involved
in the superior aspect of the tumor, and therefore careful
attention must be paid to these vessels as the superior
aspect of the tumor is removed.
Outcome
There is controversy as to the necessity of surgery, as it
has been clearly shown that these\tumors are highly ra-
diosensitive, with long tu1nor—free\intervals in 55 to 90
percent of patients treated with cranial irradiation (206-
209). In fact, the tumor is so very sensitive to irradiation
that it has been shown to disappear on\CT when as little
as 1,200 rads have been administered to the tumor area.
Adjunctive radiotherapy should be given to all patients
who do not have complete surgical removal of the
tumor.
Neuwelt and associates have reported two patients
with suprasellar germinomas, one with extraneural ine-
tastasis via a ventriculoperitoneal shunt and the other
with CNS recurrence and metastasis, who responded to a
combination of cis—platinum, bleomycin, and vinblas—
tine. Both tumors secreted the B30 subunit of human
chronic gonadotropin, which was a useful marker for
follow—up during remission (20,210).
COLLOID CYSTS OF THE THIRD VENTRICLE
Incidence
Colloid cysts of the third ventricle are uncommon,
accounting for less than 1 percent of all intracranial neo-
plasms. They will be recognized rnore frequently with
CT and MRI scans, however, which are being mcreas—
ingly used to evaluate headaches and dementia.
Symptoms and Signs
Generally, there are three forms of presentation (21 1):
(1) a nonspecific syndrome of increased intracranial
pressure without localizing signs; (2) progressive dernen—
tia with or without headache, associated at times with
intracranial hypertension; and (3) paroxysmal attacks
with complete recovery in between.
Headaches are the most common initial complaint,
and may remain the sole complaint. At times, the head-
aches are paroxysmal attacks of pain, usually diagnosed
as migraine attacks. Occasionally, the headaches are re-
lieved by a change in position, such as lying down. De-
mentia, with recent memory loss, and visual symptoms
such as blurring, temporary loss of vision, and diplopia
can occur. Black—out spells, with drop attacks described

by the patient as sudden weakness of the legs, have been
observed to be symptoms of colloid cysts of the third
ventricle. Although the neurological examination is fre-
quently normal, papillederna may be present because of
the increased ICP. An organic mental syndrome may be
observed. Ataxia and pyramidal tract signs may be pres-
ent as well.
Pathology
These tumors are well—circumscribed cystic masses,
with a smooth, translucent membrane. This cyst rne1n—
brane is composed of connective tissue, with a layer of
cuboidal or columnar cells lining the interior surface.
The cyst contains a homogeneous gelatinous liquid.
Diagnostic Studies
CT or MRI is the diagnostic study of choice. These
studies demonstrate a homogeneous, usually hyper-
dense, lesion with a smooth contour attached to the roof
of the third ventricle, generally at the foramen of Monro
although the tumor can also lie more posteriorly or in
the septum pellucidurn. There is usually some enhance-
ment after injection of contrast agent. Hydrocephalus of
a variable degree is present in nearly all cases. This has
been noted to be caused not by a block at the foramen of
Monro, but rather by occlusion of the posterior third
ventricle and aqueduct.
Angiography usually shows ventricular dilatation and.
in the majority of cases, classical venous changes caused
by elevation of the proximal portion of the internal cere-
bral vein.
Operation
Various methods have been used for treatment of pa-
tients with colloid cysts of the third ventricle. Some pa-
tients have only had spinal fluid diversion procedures.
Before considering the operative approaches to the third
ventricle, the anatomy must be carefully studied.
The third ventricle is one of the most surgically inac-
cessible areas in the brain, being a narrow, funnel—shaped
midline cavity bounded above by the corpus callosuin
and the body of the lateral ventricle, and below by the
sclla turcica, the pituitary gland, and the midbrain. It hes
between the two halves of the thalamus and hypothala-
mus. It is closely related to the circle of Willis and its
branches and to the great vein of Galen and its tributar-
ies. The third ventricle communicates at its anterosupe—
rior margin with each lateral ventricle through the fora-
men of Monro and posteriorly with the fourth ventricle
through the aqueduct of Sylvius. It has a ﬂoor, a roof,
BRAIN TUMORS
and anterior, posterior, and two lateral walls (212).
These landmarks should be studied prior to operation on
a tumor in the third ventricle.
The routes through which the third ventricle can be
reached are: (1) from above, through the foramen of
Monro and roof afterl entering the lateral ventricle
through the corpus callosuin or the cerebral cortex; (2)
from anterior, through the lamina terminalis; (3) from
below, through the ﬂoor; and (4) from posterior, through
the pineal region or from the posterior part of the lateral
ventricle. Specific operative approaches are indicated de-
pending on whether the turner is located in the anterior
or posterior part of the third ventricle.
The general principles include the following:
1. The craniotomy ﬂap should be placed so as to mini-
mize the need for brain retraction.
2. Incisions in neural tissue and sacrifice of neural struc-
tures should be minimized.
3. Tissue should be removed from within the capsule of
a third ventricular tumor before trying to separate the
capsule from adjacent structures. The most common
cause of tumor appearing to be adherent is not adhe-
sions between the capsule and surrounding struc-
tures, but rather residual tumor within the tumor cap-
sule (213). As the intracapsular contents are removed,
the tumor collapses, thus making it possible to re-
move more tumor through a small opening.
4. Any arteries that pass over the tumor capsule to
neural tissue should be preserved by displacing vessels
off the tumor capsule using a small microdissector.
5. The number of veins sacriﬁced should be kept to a
minimum. Attempts should be made to displace
veins before obliterating tumor.
6. Any obstruction to the ﬂow of spinal ﬂuid should be
removed if possible. Otherwise, a spinal ﬂuid diver-
sion procedure will be necessary.
The anterior transcallosal approach is useful for le-
sions located in the anterosuperior part of the third ven-
tricle. This approach is easier to perform than the trans-
ventricular transcortical approach if the ventricles are
small. The anterior transventricular transcortical ap-
proach is useful for tumors in the same position if the
tumor has a major extension into the lateral ventricle. It
is imperative that special care be taken to protect the
fornices from damage during the operation.
The transcallosal approach using magnification tech-
niques offers several advantages. Cortical tissue need not
be removed, and this approach is usually not associated
with neurological sequelae, although Jeeves, Simpson,
and Geffen have reported some impairment of the
transfer of tactile information (214). On the other hand,
this approach requires more dissection of the anterior
cerebral arteries.

138 / CHAPTER8
Often the tumor is attached to the tela choroidea of the
anterior third ventricle, and therefore it separates the two
fornices and the two leaves of the septum pellucidum.
This allows further separation of the two fornices at
operation, exposing the tela choroidea of the anterior
third ventricle which can then be divided in the midline
between the two internal cerebral veins. This gives the
surgeon excellent exposure of the anterior third ventricle
and the tumor.
It must be stressed that colloid cysts are not simple to
treat. Some are large and have a wide attachment to the
roof of the third ventricle. Others are located more poste-
riorly and grow into the septum pellucidum. Sometimes
there are dense adhesions between the capsule, choroid
plexus, and deep venous structures, especially the paired
internal cerebral veins. Antunes, Louis and Ganti have
documented postoperative hydrocephalus requiring
shunt procedures in three of eight patients who under-
went a microsurgical transcallosal removal of their col-
loid cysts (215).
Outcome
The results of treatment should be excellent. Antunes
and associates reported on 23 patients with a colloid cyst
(215). Twelve patients did well, two developed seizure
disorders postoperatively, one patient with organic 1nen—
tal syndrome did not improve, one had a hemiparesis,
and another had a severe postoperative memory defect
secondaiy to fornix section. Four patients died, appar-
ently because of increased intracranial pressure.
MENINGIOMAS
Meningioina as a specific type of minor was first de-
scribed in 1774 by Antoine Louis, a leading French sur-
geon, in his "Mi1noire sur le tumeurs Fongueuse de la
Dure—1nere" (216). The tumors arising from the dura
were generally called fongus or fungus for well over a
century; this is how they were referred to by Virchow in
1864 (32), although by that time some authors referred
to them as endotheliomas. The term "rneriingio1na" was
coined by Harvey Gushing.
Incidence
In historical reviews, meningiomas account for about
14 to 18 percent of all intracranial primary neoplasms.
Combining the brain tumor series of Olivecrona, Zulch,
Bal1r and Kernohan and Snipe, the average percentage
of meningiomas was 17.4 percent (108). Meningiomas
occur at any age, but most commonly present in middle
age, with a peak incidence around 45 years of age. Only
about 1 percent of all intracranial tumors in patients
under 20 are meningiomas, and they are therefore rare in
children. Meningiomas are more common in females
than in males, with a ratio of 6:4. In a study of incidental
brain tumors found at autopsy, one—third were menin-
giomas, usually located in the parasagittal region; the
majority were less than 2 cm in size. Most meningiomas
found at autopsy are asymptomatic. Multiple and farnil—
ial meningiomas may be found in von Recklinghausen's
disease, but have been reported in persons without neu-
rofibroinatosis as well (100,217). \
Etiology
The controversy concerning the relationship between
head trauma and tumors of the brain is particularly perti-
nent when considering the etiology of intracranial ine-
ningiomas. Many cases have been cited in which there is
convincing evidence that the site of previous trauma was
the exact location where the tumor subsequently devel-
oped (13,218). Indeed, it was Gushing and Eisenhardt
who stated in 1938 that "ofall intracranial tumors in our
experience, the incidence of trauma in the meningiomas
is particularly high. It was recorded in nearly one—third of
the entire number,. . . the direct relation of the blow to
the locus of the ensuing growth is not infrequently so
precise that the conclusion that an etiologic factor in-
volved is inescapable" (9). Meningiornas have definitely
been reported to occur in the exact site of previous
trauma (12) and have been likewise reported follow-
ing radium therapy for a cutaneous malformation
(219-222).
Symptoms and Signs
The average preoperative duration of symptoms for
meningiomas in general is 2'/2 years (1). Meningiomas
are especially noted to cause seizures. In Ramamurthi,
Ravi, and Ramachandran's series of 127 consecutive pa-
tients with a meningioma, a seizure as the initial syrnp—
tom occurred in 29 percent (223). Of these patients, only
50 percent obtained relief of their seizures following
operation.
Meningiomas, as will be described below, usually pre-
sent with symptoms and signs associated with the area of
the brain where the lesion occurs. For instance, a menin-
gioma of the middle third of the falx classically presents
with focal, contralateral motor or sensory seizures, or
with progressive hemiparesis. Meningiomas may pre-
sent, though rarely, with other symptoms. Hemorrhage
may occur into a meningioma or into the subarachnoid
space (224-227). This is characterized by sudden severe
headache, lethargy, and focal neurological deﬁcit such as

hemiparesis. Meningiomas associated with hemorrhagic
complications show no predilection for age, sex, or tu-
mor location. Meningothelial, angioblastic, and fibro-
blastic meningiomas have been associated with hemor-
rhage. It is easy to appreciate the potential for
hemorrhage in an angioblastic meningioma because of
the abnormal vasculature. Rarely, a falx meningioma
may present as episodes of transient ischemia caused by
a blood steal from the brain to the highly vascular tumor.
Transient episodes of cerebral ischemia are most often
seen with parasellar meningiomas, as a meningioma of
the medial sphenoid ridge or parasellar region may
narrow or occlude the adjacent carotid artery (228).
Sagittal Sinus and Falx Meningiomas
The most common location for meningiomas is along
the sagittal sinus and falx (6). This is believed to be re-
lated to the abundant pacchionian granulations of this
area. The parasagittal meningioma is at least five times
more common than the falx meningioma, and together
they account for nearly 25 percent of all intracranial
meningiomas (229).
The parasagittal tumor, as strictly defined, attaches to
the superior sagittal sinus and occupies the space be-
tween the falx and the convexity dura, indenting the me-
dial surface of the hemisphere. The sagittal sinus may be
encroached upon or even occluded by invasion of the
tumor which may grow over the hemisphere or down-
ward below the falx. The pericallosal artery and the cor-
pus callosurn are then depressed downward by the tumor
mass or associated edema.
Although the falx meningioma may appear to be on
the surface of the brain by CT or MRI examination, at
operation the tumor is hidden beneath the cortical sur-
face. It may arise from the falx or inferior sagittal sinus,
again indenting the medial hemisphere. It may also grow
through the falx and become bilateral or, as it enlarges,
may appear as a parasagittal meningioma.
These tumors tend to occur at the middle one—third of
the sagittal sinus, with the posterior one—third the least
likely site. Some occur at the torcula. Meningiomas that
arise from the anterior one—third are particularly likely to
grow very large before becoming clinically evident.
Headache is the predominant symptom usually fol-
lowed by the insidious deterioration of memory, intelli-
gence, and personality. Tremor and urinary inconti-
nence may also be present.
Meningiornas of the middle third of the sinus often
present with focal epilepsy, usually commencing in the
foot. Spastic weakness of the foot then occurs. The most
posteriorly located tumors may produce prominent sen-
sory findings. Menmgiornas of the posterior one—third
may produce homonymous hemianopsia, frequently
BRAIN TUMORS 159
unnoticed by the patient until an accident occurs while
driving, or until signs of increased ICP develop. Visual
seizures are uncommon, but occasionally episodes of
scintillating bright lights are mentioned by the patient.
C onvexily M eningiomas
Convexity meningiomas constitute about 18 percent
of all meningiomas an\l tend to be concentrated in the
region of the coronal suture. In some series, this is the
largest group of meningiomas. Seizures and focal neuro-
logic deficits are very common, and often the tumor
reaches large size, causing signs of increased ICP.
Sphenoid Ridge M eningiomas
The sphenoid ridge is an important boundary between
the anterior and middle fossae. The lesser curvature
makes up the inner two—thirds of the sphenoid bone over
the anterior clinoid. The greater wing makes up the outer
third, which extends to the pterion. Eighteen percent of
meningiomas are located on the sphenoid ridge and may
grow into the anterior fossa, middle fossa, sylvian fissure,
orbit, or cavernous sinus. Meningiomas of the inner
sphenoid ridge usually involve the optic nerve early in
their growth. There may be a long history of progressive
visual loss: optic atrophy and a temporal ﬁeld defect may
be present in the affected eye. As the tumor progresses,
the chiasm becomes involved, and both eyes will have
field defects. Involvement of the cavernous sinus leads to
oculomotor paresis or sensory loss in at least the ophthal-
mic division of the trigeminal nerve and eventually in
the other divisions as well. Exophthalmos is common
and may be caused by venous congestion, local tumor
infiltration of the orbit, or hyperostosis.
The tumors of the outer sphenoid ridge may be either
globular or en—plaque. Patients with a globular menin-
gioma usually present with headaches or temporal lobe
seizures. The en—plaque tumor, which is actually a thin
or thick layer of tumor covering the dura, causes unilat-
eral exophthalmos as an initial complaint, followed by
limitation of extraocular movements, decreased visual
acuity, and temporal swelling.
Olfactory Groove Meningiomas
Meningiomas that occupy the midline ﬂoor of the an-
terior fossa constitute 18 percent of the meningiomas.
These tumors arise over the lamina cribrosa of the eth-
rnoid and protrude into the frontal lobes inferiorly and
usually bilaterally. The initial complaint should be anos—
rnia, but this is rare. Usually, these tumors become very
large and cause headaches and finally visual failure from

140 / CHAPTERS
either increased ICP or direct encroachment on the optic
nerves. A variety of field defects is seen. This tumor may
produce ipsilateral optic atrophy and contralateral papil-
lederna (Foster—Kennedy syndrome), although this is
rarely seen. Finally, mental deterioration, and bowel and
urinary incontinence may occur.
Suprasellar Meningiomas
Ten percent of meningiomas arise in the midline tu-
berculuin sellae. Even when small, the tumors will cause
bitemporal hemianopsia and optic atrophy. Thus, the
usual complaint is painless, or nearly painless, progres-
sive loss of vision, which is usually asymmetrical and
much more severe in one eye than the other. In fact,
there may be complete loss of vision in one eye for years
before visual loss is observed in the opposite eye. If the
tumor grows forward, it may produce anosmia or mental
changes. If it grows posteriorly, there will be oculomotor
and pituitary deficits. In the past, these tumors often
went undiagnosed for years, as the patient's vision deter-
iorated to blindness in one eye. With the advent of CT
scanning, these lesions should be recognized prior to se-
vere visual loss.
Optic Serve Meningiomas
Optic nerve meningiomas fortunately are rare. The
classical presentation is of a central scotoma, breaking
out over time into a peripheral defect in a rniddle—aged
woman. The visual loss is slow, painless, and progressive.
Opticociliaiy shunt vessels may be present on fundusco—
pic examination. Optic atrophy eventually develops.
The bilateral form is among the most difficult of all tu-
mors to diagnose before severe loss of vision has oc-
curred. Prior to 1979. only seven patients with histologi-
cally proven bilateral optic nerve sheath meningiomas
had been reported: another two patients with bilateral
signs suggestive of such tumors had been explored on
one side only (230231).
Posterior F ossa M eningiomas
About 9 percent of meningiomas occur in the poste-
rior fossa. Castellano and Ruggioro have divided these
tumors into five groups (233). The first group includes
the 40 percent ofthese tumors that arise along the poste-
rior surface of the petrous bone. The tumor involves cra-
nial nerye VIII, and frequently V and VII. Both trigerni—
nal neuralgia and hemifacial spasm have been seen with
a tumor in this location. Ataxia and nystagmus are fre-
quently observed. Finally, as the fourth ventricle is
shifted and the foramina are occluded, hydrocephalus
and increased ICP occur. Often the signs of this tumor
are highly suggestive of acoustic neurinoma.
Another group are those tumors that grow in the re-
gion of the tentorium, comprising 30 percent of poste-
rior fossa meningiomas. These tumors commonly in-
vade venous sinuses and may extend above the
tentorium. These turners usually cause symptoms of in-
creased ICP.
Ten percent of posterior fossa meningiomas arise
from the clivus. They cause posterior headaches, gait dis-
turbances, decreased Wealing, vertigo, dysphagia, and
weakness. Papilledema, nystagmus, lower cranial nerve
palsies, and cerebellar and pyramidal signs are also ob-
served. These signs are sometimes intermittent and remi-
niscent ofbasilar artery insufficiency or may be confused
with intrinsic brainstem tumors or cerebellopontine an-
gle tumors.
Tumors of the cerebellar convexity comprise a group
of about 8 percent of all posterior fossa meningiomas.
They are usually near the transverse sinus and produce
symptoms of increased ICP and hydrocephalus by dis-
placing the cerebellum forward and obstructing the aque-
duct. Disturbances of gait and cranial nerve signs occur.
The last group oftumors, comprising 8 percent ofpos—
terior fossa meningiomas, are located at the foramen
magnum. They account for 1.2 percent of all meningio-
mas. The first case of meningioma at the foramen 1nag—
num was described by Hallopeau in 1874 (232). There is
some controversy as to tumor location for consideration
as a foramen magnum meningioma. Castellano and
Ruggioro (233), as well as others, considered as foramen
magnum meningiomas only those attached to the dural
edge of the foramen magnum or to the inferior grove of
the clivus. Gushing and Eisenhardt advocated that this
term should be restricted to neoplasms extending into
both the posterior fossa and the cervical spinal canal (9).
The time interval from initial symptom to diagnosis of
a meningioma of the foramen magnum has been re-
ported to range from months up to 13 years. In the past,
this has been a most difficult tumor to diagnose and the
duration of the disease is long. There are no symptoms
pathognomic of a tumor at the level of the foramen rnag—
num. A collection of symptoms and signs is commonly
found in association with these lesions. The initial syrnp—
tom is usually pain in the cervical region, exacerbated by
ﬂexion of the neck, pressure in the neck, coughing, or
straining. Sensory and motor symptoms follow, usually
commencing in one arm and progressing to involve the
remaining limbs. Ataxia and sphincter disturbances are
common. There may be variable and bizarre sensory
dysesthesias. Psychosis and neurosis may coexist, lead-
ing to a diagnosis of hysteria.
The initial examination may show normal results or
only subtle abnormalities in almost halfthe patients. Pos-
itive findings rnost commonly include hyperreﬂexia and
weakness, particularly of one or both upper limbs pro-
gressing to involve the remaining limbs. Clinical findings

are horizontal nystagmus; palsy of the lower cranial
nerves, generally the hypoglossal; atrophy of the hands;
and intercostal muscle atrophy. Hypesthesia of the sec-
ond ceryical dermatome is an important finding when
present. The typical features of the sensory disturbances
are cold dyesthesias, which are considered an early sign
ofextramedullary tumor at the foramen magnum. Burn-
ing dyesthesias precede the onset of hypesthesia. Sy1np—
toms related to the posterior column, such as pseudoc—
tereognosis, otherwise called the piano—playing—fingers
phenomenon, and stereoanesthesia are at times ob-
served. Cerebellar signs and papilledema are un-
common.
Thus, the clinical picture can suggest many other dis-
eases. The confusion with an intramedullary tumor or
syringomyelia is obvious. A foraminal tumor is easily
misdiagnosed as demyelinating disease, degenerative
disease, or cervical spondylosis.
Lateral and Third Ventricle Meningiomas
Meningiomas that arise from the tela choroidea or the
stroma of the choroid plexus of the lateral ventricle con-
stitute only about 2 percent of all meningiomas. These
tumors are rare in the third ventricle, and they usually
occur in the atrium of the lateral ventricle. Only about
100 cases of a meningioma of the ventricles were re-
ported in the English literature between 1900 and 1978,
when Mani and associates reported 22 cases with 13 of
the meningiomas being in the left lateral ventricle (234).
The presenting symptoms of patients with ventricular
meningiomas are nonspecific. Headache is the present-
ing syrnptorn in 40 to 70 percent of patients, followed
closely by hemiparesis in 20 to 60 percent of patients.
Visual changes, memory loss, grand mal seizures, apha-
sia, vertigo, loss of consciousness, and personality
changes have been observed. These tumors have been
observed as a cause of subarachnoid hemorrhage. Also,
xanthochromia suggesting a previous hemorrhage has
been observed in some cases of intraventricular menin-
giomas (235).
Other Sites 0fMeningi0mas
A small number of tumors grow in Meckel's cave, in-
volve the gasserian ganglion, and produce typical trigemi—
nal neuralgia. As the tumor enlarges, it invades the cav-
ernous sinus or spreads into the cerebellopontine
angle.
Pathology
The arachnoidal cell is believed to be the cell of origin
of meningiomas. Ultrastructural analysis reveals many
BRAIN TUMORS 1 41
features of normal araclmoidal cells and meningioma
cells that are identical.
Meningiomas are globular, rarely pancakelike. or en-
plaque, and are usually firmly attached to the dura, with
a sharp demarcation from surrounding brain. Their sur-
faces may be smooth (I nodular. Small tumors may
merely indent the brain, but very large tumors may de-
stroy the cortex. Surrounding brain edema is not related
to tumor size, as small tumors may be associated with
massive edema which may produce clinical symptoms
itself. Rarely are meningiomas cystic.
Hyperostosis of the inner table of the skull occurs in
about 5 percent of patients with a meningioma. At times,
the outer table becomes involved and produces a visible
mass, more common in parasagittal tumors. The hyper-
ostosis associated with en—plaque sphenoid wing menin-
giomas may extend into the orbit and temporal fossa.
Microscopically, several histological classifications
have been used for these tumors. The most widely used is
the classification proposed by Courville and adopted by
Russell and Rubinstein. Five categories are designated:
syncytial, transitional, fibrous, angioblastic, and malig-
nant, with gradations often occurring among these
various types (I).
The syncytial or meningotheliomatous type consists
of poorly denned polygonal cells arranged in sheets sepa-
rated by vascular trabeculae. The cytoplasm is homo ge-
neous, the nuclei are spheroidal, and collagen reticulin
fibers are sparse and conﬁned to the vascular stroma.
The transitional form, along with the syncytial tumors,
comprises 65 percent of the total pathological spectrum
of meningiomas. A formation ofconcentrically arranged
cells is characteristic of transitional meningiomas. Cen-
tral hyalinization and deposition of calcium salts pro-
duce psamrnorna bodies typical of this form of rnenin—
gioma. The fibroblastic or fibrous type of meningioma is
composed of interlacing bundles of spindle cells, rich in
reticulin and collagen ﬁbers.
Angioblastic meningiomas are highly cellular with
prominent vascular channels and frequent mitoses. The
vessel walls and stroma have abundant reticulin fibers.
These tumors may look like hemangioblastomas by both
light and electron microscopy but differ in gross features
and location. The angioblastic meningiomas tend to be
supratentorial, attached to the dura, cystic, and at times
associated with tumors in other organs.
The incidence of malignant meningiomas is reported
to be 2 to 10 percent of all meningiomas, with a male
predominance—a reversal of the usual gender predilec-
tion of meningiomas. Malignancy can be identified by
various criteria including local invasion of the brain;
atypical histological features, such as high cellularity,
high mitotic rate and poor differentiation; extracranial
differentiation and metastasis; and rapid recurrence. Lo-
cal invasion of bone, dura, or venous sinuses is not a

142 / CHAPTERS
criterion for malignancy, but brain invasion is. Mitotic
figures probably represent rapid growth and not malig-
nancy. On the other hand, cellular progression of a typi-
cal meningioma to that of a spindle—cell sarcoma, or the
cytological appearance of increasing anaplasia, denote
malignancy. A papillary pattern histologically is also a
sign of malignancy; this feature has been particularly
noted in meningiomas in children. The presence of ine-
tastasis is an absolute criterion of malignancy (216). The
lung is the most frequent site involved, followed by the
liver and bone. The dissemination is most likely via the
venous system with the parasagitial tumor the most
likely to rnetastasize. Angioblastic meningiomas account
for a greater number of metastases than their relative
frequency would suggest (236). Dissemination via the
cerebrospinal pathway has been reported in only eight
cases (237). Recurrence of meningiomas, particularly
after incomplete removal, occurs in at least 20 percent of
patients who undergo surgical treatment of their menin-
giomas. Crompton and Gautier—Smith studied recurrent
and falx meningiomas and suggested certain histological
features as pointers to possible early recurrence (238).
These were the presence of mitotic figures, focal necro-
sis, and permeation of the brain by tumor.
Diagnostic Studies
Review of the plain x—ray may be extremely reward-
ing; in about one—half of the cases the diagnosis can be
suspected from the plain x—ray. There may be indirect
evidence of a tumor such as abnormal convolutional
markings, pressure atrophy of the sella turcica, or dis-
placement of physiologically calcified structures; or di-
rect evidence of a meningioma with hyperostosis, in-
creased vascular markings, or tumor calcification.
Hyperostosis is the most frequent sign and most corn-
monly involves the inner table of the skull. The menin-
geal vascular groves may be enlarged with abnormal
branching near the tumor. About 10 percent of menin-
giomas show a cloudlike globular calcification or a sirn—
ple ringlike outline of the tumor.
Arteriography is most helpful in defining the nature,
location, and extent of the meningioma, as well as its
relationship to important vascular structures. A homoge-
nous but sharply circumscribed tumor stain is frequently
seen, and may persist because of prolonged circulation in
the tumor or because the contrast material actually
leaves the vascular system and enters the extracellular
space. Arteriography remains helpful in the manage-
ment ofthese tumors as the important vascular supply to
the tumor needs to be visualized before embolization or
surgery can be properly planned.
CT and MRI scans are the most accurate noninvasive
tests for identifying meningiomas. Claveria and asso-
ciates, in an analysis of 71 cases of meningioma diag-
nosed by computerized tomography using a 160 x 160
matrix, concluded that with contrast injection a diagno-
sis of tumor could be made in 96 percent of the cases
(239). The difficult areas to examine by CT for the pres-
ence of a meningioma are the sites adjacent to the calvar—
iurn or base of the skull, sych as the parasagittal region,
the tuberculuin sella—parasellar area, the optic canal, and
the cerebellopontine angle, because of the superposition
of the density of the tumor and the density of the skull.
MRI is the superior diagnostic test for these tumors be-
cause of the ability to subtract bone from the image. For
meningiomas of the foramen magnum, MRI is clearly
the diagnostic test of choice. Although CT is able to visu-
alize the foramen magnum region well, MRI is better
able to delineate the tumor and differentiate neurologi-
cal structures and cerebrospinal fluid spaces. MRI using
the inversion recovery sequence and gadolinium—diethy—
lene triamine pentoacetic acid (DTPA) contrast medium
will give good definition in over 96 percent of cases. Un-
like CT and myelography, MRI does not show bony alti-
facts. An added advantage of MRI is that vasculature
structures such as the vertebral artery are seen as a void
signal. Most foramen magnum meningiomas occur at
the anterolateral tip of the foramen and the vertebral
arteries are generally encompassed by the tumor. MRI
not only demonstrates the location of the artery in rela-
tion to the tumor and other brain structures but also is
useful in separating the tumor from the vessels.
On CT, meningiomas are usually seen as high—density
areas with well—defined round borders and striking con-
trast enhancement, although the borders may also be
irregular, associated with a variable amount of edema or
cyst formation (240). CT scanning has been suggested by
Vassilouthis and Ambrose as helpful in predicting histo-
logical features ofmeningiomas (241). In particular, visi-
ble calcium aggregates point to a diagnosis of either tran-
sitional or ﬁbroblastic meningioma. Since most tumors
are surrounded by edema of varying degrees, edema is
not a specific feature of meningiomas. Angioblastic and
syncytial meningiomas show a marked tendency to ex-
hibit low—density, nonenhancing "cystic" areas, or
poorly defined, irregular tumor margins or fringes. The
presence of marked edema, absence of visible calcium
aggregates, and nonhomogeneous contrast enhance-
ment with hypodense areas and poorly defined irregular
borders or fringes point to aggressive or invasive charac-
teristics rnore commonly found in nonbenign or aggres-
sive meningiomas. New and coworkers, in their report
on CT criteria for malignant meningiomas, Cl6SC1’lb6Cl
another CT sign, which they called the mushrooming
pattern (242).
Operation
In 1954, Dr. Frances C. Grant noted, "A meningioma
is a benign tumor, which if it can be completely extir-

pated together with its meningeal attachment will not
recur." He further stated in the same paper that "a sub-
total removal without aggravation of existing neurologic
deficit will be more satisfactory to the patient and to his
family than a complete removal and the assurance of a
long life severely crippled" (243). Nearly 30 years later,
these tenets still hold true and should remain foremost in
the mind of every surgeon as the care of a patient with a
meningioma is undertaken.
The preoperative evaluation always has and always
will be critical in the preparation ofthe patient for opera-
tion. The plain skull X—ray still plays a role in planning
the operation for a patient with a meningioma. The pres-
ence of skull changes produced by the tumor will allow
precise placement of the bone ﬂap. The vascular rnark—
ings are important as they can forewam the surgeon of
potentially severe bleeding, which may accompany
opening of the bone ﬂap. Hyperostosis or tumor in the
bone will alert the surgeon as to the need for cranioplasty
(Fig. 6).
The arteriogram will define the degree of vascularity,
the arterial supply, and venous drainage of the tumor.
Adequate control of the arterial supply and preservation
of normal venous drainage of the brain are among the
most important considerations of the operation. An ex-
tremely vascular tumor may be diagnosed as an angio-
blastic meningioma, or at least alert the surgeon to the
probabilities of severe hemorrhage if the tumor is incised
or debulked piecemeal prior to occlusion of the arterial
supply. The relationship of the major intracranial arter-
ies is critical. A determination rnust be made whether
these arteries are displaced by or encased in tumor. Ifthe
BRAIN TUMOBS 1 43
turnorisdisplacingthevessels,microsurgicaltechniques
mayallowremovalofthetumorfromthevessels.Ifitis
determined the vessels are totally encased by tumor.
then complete tumor removal may be impossible. Heop—
erative planning may then include an extracranial—intra—
cranial vascular anastomosis prior to tumor removal if a
major intracranial vessel is to be compromised by the
operation.
The arterial phase of the arteriogram is of utmost irn—
portance for planning methods that may be beneficial in
reducing the blood supply to the tumor. This may in-
volve ligation of the external carotid artery or selective
ernbolization of the tumor—feeding vessels. There are
some instances in which preoperative ernbolization of
feeding vessels of the tumor can dramatically reduce in-
traoperative hemorrhage. Placement of emboli directly
into the tumor causes the most effective reduction in
vascularity, thus decreasing blood loss during surgery.
Hieshima and colleagues have shown pathologically
zones of infarction in 10 of 11 tumors embolized and
evidence of decrease in size of some of the tumors on
CT (244).
The venous phase ofthe arteriogram is as important as
the arterial phase. Although the CT may be able to reveal
patency or occlusion of the sagittal sinus, the venous
arteriogram or direct sinogram is the definitive proce-
dure for determining sagittal sinus patency. The condi-
tion of the sagittal sinus must be determined in all pa-
tients harboring parasagittal faix and tentonal
rnernngiornas. It is well known that the sagittal sinus can
be safely ligated in only the anterior one—third of its ex-
tent or. in generai only anterior to the coronal suture. If
’-tmi:n]1&M. > 42-" ——
FIG. 6. (A) Enhanced CT scan of asymptomatic patient showing invasion of bone by the frontal convex-
ity meningioma; (B) inner table of bone plate of hypertosis caused by the tumor.

144 / CHAPTERS
tumor only partially invades the sinus posteriorly, every
attempt must be made to completely remove the tumor,
but the sinus and cortical draining veins must be pre-
served. Careful preoperative planning and preparation
of the patient permits reconstruction of the sinus. This
can be done by using the Kapp—Gielchinsky shunt dur-
ing removal of tumor from the sinus and repair of the
sinus by autologous saphenous vein graft (245246). If
the superior sagittal sinus is completely occluded by tu-
mor, and collateral drainage, usually via the inferior sag-
ittal sinus, is preserved, then the sinus can be safely re-
sected without further increase in neurological deficit.
Equally important is the preservation of the large cor-
tical draining veins, especially frorn the parietal and oc-
cipital lobes. The approach to the tumor should be
planned so as to preserve these draining veins, or venous
infarction may be produced resulting in cerebral swell-
ing, profound neurological deficit, and seizures.
Preoperative Medications
The patient should be prepared with adequate preoper-
ative anticonvulsant medications, even ifthe patient had
not had previous seizures. Dilantin and phenobarbital
can be safely used in most patients, although a few will be
allergic to dilantin. The surgeon should be aware of this
fact as dilantin may be the culprit in a persistent postop-
erative fever or rash. Anticonvulsant medication for two
to three days prior to operation is recommended, but
rapid dilantinization can be done ifurgent surgery is nec-
essary.
Dexamethasone, in large doses, or a similar steroid for
at least three days preoperatively, and preferably for five
days, will reduce any surrounding brain edema. A grad-
ual reduction of steroids over a similar period postopera-
tively is done depending on the patient's course.
Technique
Adequate exposure is important in every operation. In
most operations for a meningioma, the bone ﬂap should
be a free ﬂap completely detached of its muscular attach-
ments and blood supply. This will lessen the chance of
postoperative epidural hematoma. The bone ﬂap should
be inspected for evidence of tumor invasion, and if this
exists, the bone ﬂap should be discarded or the area of
tumor invasion removed completely by drilling out the
tumor. This at times can be done with an air turbine and
cutting burrs, as the tumor may involve only the inner
surface of the bone. If the bone ﬂap is to be replaced, any
existing vascular groves must be generously waxed or
covered with Avitene.
The bone ﬂap for paiasagittal and falx tumors will
usually need to be fashioned so as to cross the midline,
even though the tumor appears unilateral (247). This
permits control of the sagittal sinus by ligation or resec-
tion of the anterior part of the sinus. At times, the tumor
will have a dumbbell extension across the midline, re-
quiring removal. Although slightly more time consum-
ing than a unilateral flap, the bilateral flap can be safely
fashioned by placing burr holes over the midline sinus.
This will protect the sinus from any laceration by the
craniotome or Gigli saw. An alternative, as reco1n—
mended by Kempe, is the placement of burr holes on
either side of the venous sinus\and then connecting the
holes with a craniotome after freeing the dura and sinus
from the bone (248).
In operations for 1neningiornas\particular attention
must be paid to the dura. When the dura is exposed,
visual inspection may reveal the extent of the dural in-
volvement with the tumor. Any dura involved with tu-
mor will need to be removed with the tumor, and re-
placed with pericranium, galea, or fascia lata. We do not
favor the use of artificial dura mater, especially silastic
implants, unless absolutely necessaiy because of adverse
reactions we and others have observed with this material.
Late hemalomas and large granulomatous reactions
forming a mass and requiring reoperation have been re-
ported (249). Therefore, only dura involved by tumor
should be removed as this will require less replacement.
Gentle palpation of the dura and an initial opening over
the lateral margin of a parasagittal or falx meningioma
will show the direction of the dural opening, which
should be made first beyond the firm attachment or in-
vasion ofthe dura by the tumor. A circumferential dural
opening may decrease blood supply and permits use of
the dura for traction and gentle delivery of this tumor as
it is removed (250).
In the removal of falx, parasagittal, and convexity
meningiomas, it is imperative that the tumor be re-
moved from the brain and not the brain from the tumor.
In falx meningiomas, some gentle retraction of brain is
necessary, but this should never be forceful. Proper pre-
operative use of steroid medication, plus intraoperative
mannitol and anesthetic techniques, will allow the brain
to fall away from the tumor with gentle retraction. Un-
due retraction may tear vessels, lacerate brain, or aggra-
vate cerebral edema, producing a difficult postoperative
course. Mechanical self—retaining retractors, such as the
Leyla retractor, are preferable to manual retraction
which may cause more trauma to the brain.
The bipolar coagulator is an indispensable instrument
for safe control of the feeding arteries and draining veins
of a meningioma. The use of metal clips for hemostasis
may interfere with postoperative CT or MRI scanning.
Microsurgical techniques using the operating rnicro—
scope are useful in the removal of most meningiomas
and are indispensable for basal tumors involving cranial
nerves or major cerebral vessels. For large parasagittal,
falx, and convexity tumors, loupe magnification is
usually sufficient. Removal of a large tumor requires ap-

proaching the tumor from all sides and frequent chang-
ing of the microscope positions becomes cumbersome
and tedious. If the surgeon uses loupes, there is greater
ease in visualizing all sides of the tumor during mobiliza-
tion of the tumor. Rapid excision of any brain tumor as a
primary goal is to be condemned, as speed is not the
essence of the modern operation. Rather, a zone of cleav-
age between brain and tumor is developed by separating
any adhesions by coagulation and cutting feeding ves-
sels. Soft and fragile surrounding brain tissue is carefully
protected by wet telf a strips introduced into the plane of
cleavage. Reduction of tumor mass with ultrasonic aspi-
ration is often necessary to collapse the tumor into a
small mass. In the falx meningioma, the attachment to
the falx should be generously removed, sparing the supe-
rior and inferior sagittal sinuses.
The tumor bed, blood vessels, and dural margins
should be inspected for remaining fragments of tumor.
The dural closure, with or without a graft, should be
water—tight. No tumor bed drains should be necessary,
but a subgaleal hemovac drain is routinely used by many
surgeons to prevent the development of a subgaleal he-
rnatoina which appears to increase postoperative 1norbid—
ity. Rather than increase infections in this space, a drain
if removed within 24 hours possibly lessens the chance of
infection from stagnant blood and reduces tension on
the incision.
Basal meningiomas include the olfactory grove, supra-
sellar, medial sphenoid ridge, and petroclival meningio-
mas. Special considerations for surgical removal of these
tumors, and for meningiomas of the tentorium and lat-
eral ventricles, are discussed below.
Olfactory Grove Meningiomas
Durante in 1885 successfully removed an olfactory
grove meningioma (251). This is believed to be the first
successful operation for an intracranial tumor. Success-
ful removal of an olfactory grove meningioma often has
a most gratifying postoperative result. Even when the
tumor is large, there is striking, gradual improvement in
mentation and vision if the optic nerves were coin-
pressed by the tumor.
The attachment of these tumors to the ﬂoor of the
anterior fossa is over the posterior cribiform plate and
planum sphenoidale. To approach these tumors, a bico—
ronal hairline incision is used. When the tumor is large
and bilateral, a free bifrontal craniotomy ﬂap is pre-
ferred, especially since anosomia is already present in
most cases. Frontal lobe tissue will be found covering the
tumor. This should be gently retracted after the anterior
sagittal sinus is sectioned, so as to expose the superior
aspect of the tumor. If the tumor is large, the frontal
lobes will need to be retracted posteriorly and laterally.
The tumor can then be reduced in size with loop elec-
BRAIN TUMORS / 145
trodes or the ultrasonic aspirator so as to decompress
and collapse the tumor forward, exposing the anterior
cerebral arteries and their branches. As the tumor is re-
duced in bulk and retracted anteriorly, the optic nerves
will come into view and can be protected. The tumor can
usually be completely removed in this manner. Mac-
Carty recommends cauterizing any osteoma. rather than
vigorous removal which breaks through into the ethmoi—
dal sinuses with resultan rhinorrhea (251).
Tuberculum Sellae Meningiomas
Arteriography is indicated preoperatively to appreci-
ate the relationship of the anterior part of the circle cf
Willis to the tumor. The position of the paired anterior
cerebral arteries should be especially noted to aid in pro-
tecting them from damage. Tuberculum sellae menin-
giomas compress the optic nerves and the chiasm posteri-
orly, and generally extend anteriorly over the planum
sphenoidale a few millimeters. These tumors do not ini-
tially involve the carotid or anterior cerebral arteries.
They may, however, become larger or extend above and
below the optic nerves and chiasm, displacing the inter-
nal carotid artery laterally or the anterior cerebral arter-
ies away from the chiasm. These tumors may be very
adherent to the anterior communicating and anterior ce-
rebral arteries (252).
The usual operative approach is a right frontal craniot-
omy. Some surgeons prefer the approach to be made on
the side of the most severe visual loss as this is the side of
the greatest tumor bulk. Others prefer to approach the
tumor on the side of the most intact optic nerve so as to
always have it in view and to provide protection of the
nerve. The tumor is usually easily reached by a lateral
subfrontal exposure just in front of the sphenoid wing.
This approach has been described by Kempe, MacCarty,
and Poppen (248,253,254). Hunt, Sayers, and Yashon
approach the tumor along the sphenoid wing but also
design the ﬂap so that the anterior falx can be divided if
necessaiy (255). Symon and Logue also use the unilat-
eral right subfrontal exposure but approach the tumor
along the midline (252,256). The unilateral exposure
should be employed wherever possible, so as to preserve
at least one olfactory nerve. Otherwise, the patient will
be more disturbed postoperatively by loss of the sense of
taste, rather than the anosmia.
The blood supply comes through the dura of the tu-
berculum with very little direct supply from the carotid
or anterior cerebral arteries. The tuberculum tumo:
blood supply can be systematically interrupted by devel-
oping a plane of dissection between the planum sphenoi-
dale, tuberculum, and the tumor. When the basal blood
supply to the tumor is occluded, the tumor will be turned
from an engorged red mass to a pale gray soft tumor,
much easier to decompress and remove. The surgical

146 CHAPTER 8
laser is an excellent adjunct to use for incising the base of
the tumor from the tuberculum. Once the main blood
supply is interrupted, internal decompression of the tu-
mor is essential prior to dissecting the tumor from the
optic nerves and adjacent arteries. Magnification tech-
niques will allow complete removal of the tumor even
though the optic nerves and vessels initially appear ad-
herent to or encased by the tumor. Internal deco1npres—
sion of the tumor using bipolar coagulation and small
ring currettes or the CUSA must be done carefully be-
cause of the proximity to vital structures. The tumor can
be gently dissected and reﬂected from the optic nerve
with microdissecting instruments. This tumor does not
invade the optic nerve and can be cleanly and corn-
pletely removed frorn the nerve.
With smaller tumors, the contralateral optic nerve
may be seen just proximal to the optic canal initially or
early in the dissection along the tuberculum. The nerve
forms a useful landmark. The internal carotid artery will
be just beneath it. either slightly medial or lateral de-
pending on the amount of dislocation by the tumor.
With larger tumors, if the contralateral optic nerve is not
easily seen anteriorly, it may be best to proceed along the
initially exposed optic nerve, back to the chiasm and
then, upon freeing the tumor from the carotid and ante-
rior cerebral arteries, proceed forward from the chiasm
dissecting tumor from the opposite nerve as the remain-
ing tumor is rolled anteriorly. Even when the anterior
cerebral arteries are encased in tumor, microdissection
techniques may allow complete removal of tumor from
the vessels. Of course, in doing so, the anterior cerebral
arteries must not be sacriﬁced in an attempt to corn-
pletely remove the tumor (257).
In removing the tumor from the optic chiasm, arach-
noid will eventually be encountered and appear thick-
ened. Just beneath the arachnoid will be the pituitary
stalk, often displaced posteriorly. This should always be
preserved. Meticulous microdissection of tumor from
the stalk may nevertheless result in temporary postopera-
tive diabetes insipidute. Unless the stalk is severed or the
hypothalamus injured, this condition should be te1npo—
ran’ and easily treated.
At the completion of tumor removal, careful inspec-
tion of the dural attachment at the tuberculum will show
that dura will need to be removed along with any hyper-
ostosis. using a diamond drill. Any troublesome bleeding
encountered in this procedure can usually be controlled
with bone wax or a small amount of Avitene.
Medial Sphenoid Wing Meningiomas
Medial sphenoid wing meningiomas are among the
most difficult of all tumors to completely remove. These
large globular tumors generally form a mass on the me-
dial sphenoid wing, elevating the temporal and frontal
lobes and compressing the optic nerve and chiasm (Fig.
7). They can often be completely removed if the cavern-
ous sinus is not involved. Unfortunately, an en—plaque
meningioma involving the cavernous sinus is difficult to
remove completely, but experienced skull—base surgeons
are reporting increased success with operations done
within the cavernous sinus.
The exposure to these tumors is via a frontotemporal
exposure along the sphenoid ridge. The craniotomy ex-
tends as low as possible to permit a direct view of the
ﬂoor of both the temporal and frontal fossae. Bridging
veins from the temporal lobe to the petrosal sinus should
FIG. 7. Medial sphenoid ridge menin-
gioma. Even though the tumor is easily
dissected from the sphenoid ridge, it is
still embedded in the middle sylviah ves-
sels (arrow).

be occluded by bipolar coagulation, and then sharply
sectioned. The surgeon must have an appreciation of the
relationship of the major vessels with the tumor. If the
vessels are elevated or displaced by the globoid tumor,
the tumor can be first decompressed internally, and then
the outer margins can be removed from the vessels and
optic nerve. If the tumor encases the arteries, the tumor
can be opened and, using microsurgical techniques, of-
ten dissected frorn the vessels. Exposure is aided by
opening the medial aspect of the sylvian fissure or resect-
irrg the tip of the temporal lobe as advocated by Mor-
ley (89).
E1r—plaque meningiomas invading the frontal basal
bone and air sinuses, as well as the cavernous sinus,
make total removal almost impossible without e1r—bloc
resection of the orbit and basal frontal bone as described
by Derome and Guiot (258). Even then the tumor may
not be completely resected. It is preferable to remove as
much of the tumor and its extensions by starting laterally
and proceeding medially. When the cavernous sinus is
entered and cranial nerve damage possible, tumor resec-
tion should cease. Borrnal, Andre, Brotchi, and Born
have described the high mortality and morbidity of at-
tempts to totally remove invading medial sphenoid ridge
meningiomas, and the failure to actually accomplish to-
tal removal when it was thought to have been done at the
operation (259). They also pointed out the long survival
enjoyed by patients who did not undergo operations for
removal of this tumor. This is one meningioma, when
incompletely removed, that should receive co1rsider—
ation for postoperative irradiation or gamma knife treat-
ment, especially if symptoms and signs progress.
Petroclival Meningiomas
Petroclival meningiomas were once thought to be in-
operable, and total resection was rarely reported before
1970. Today, with the development and refinements of
microsurgical techniques and approaches, and with the
quantum improvement in neuroradiological imaging,
mortality rates of 0 to 10 percent are now being reported
by outstanding skull—base surgeons, such as Samii and
Sekhar (260,261).
The approach may be retromastoid, pterional, poste-
rior temporal, or combined retrornastoid—subternporal
with division of the transverse sinus. Samii uses a rnodi—
fied retrornastoid—subternporal approach that preserves
the transverse sinus. A temporal craniotomy is per-
formed, extending it as low as possible to the ﬂoor of the
middle fossa and posteriorly to the transverse sinus. A
suboccipital craniectomy is then executed, exposing the
transverse sinus. The mastoid process is completely re-
moved, exposing the full length of the sigmoid sinus
down to the jugular bulb. The petrous pyramid is drilled
away, the superior petrosal sinus coagulated, and the ten-
BRAIN TUMORS 147
torium transected in a lateromedial direction. The oc-
cipitoternporal lobe covered by the tentorium is re-
tracted superiorly, and the sigmoid sinus and cerebellum
are retracted medially. The vein of Labbe must be pro-
tected and not traumatized. This approach gives excel-
lent exposure of the cerebellopontine angle, the clival
region, and the craniocervical junction. In tumors that
grow extensively from the clivalregion to the sellar area,
this approach allows excellent visualization of the sellar
and parasellar area because, with the brainstem posteri-
orly and superiorly displaced by the tumor, as tumor is
removed, the surgeon has an unobstructed line of vision
from the cerebellopontine angle to the suprasellar area.
Bleeding must be kept under meticulous control because
it is difficult to tamponade tumor or brainstem bleeding
by pressure.
If the tumor invades the cavernous sinus, complete
removal will be difficult but not impossible. The cavern-
ous sinus can be entered by inferior, anterolateral, or
medial extradural approaches, or by superior or lateral
intradural approaches, because the cavernous sinus can
be viewed as a truncated pyramid. A posterior approach
does not permit easy control of any bleeding from the
intracavernous internal carotid artery. The most irnpor—
tant cranial nerves passing through the cavernous sinus,
in order of importance, are III. V-I, and VI. When the
tumor invades a cranial nerve and the nerve is healthy
proximal and distal to the area, the invaded segment can
be excised and reconstruction done by direct suture orby
interposition nerve graft. Using the posterior surgical ap-
proach with rnicrosurgical techniques, the immediate
and long—term results should be excellent.
For large anteriorly located tumors, the approach is
more difficult. The transoral—transclival surgical ap-
proach is the rnost direct operative approach to tumors
ventral to the brainstem and superior spinal cord. For
tumor removal between the clivus and C-3, this ap-
proach allows an extensive anterior exposure for re-
moval of intradural and extradural tumors. Miller and
Crockard have described the successful transoral—trans-
clival removal of anteriorly placed meningiomas at the
foramen magnum (262). The surgeon works seated
above the patient's head. A self—retaining McGarvey
three—ring retractor spreads the upper and lower jaw
widely apart and displaces the tongue and endotracheal
tube caudally. The soft palate is divided, and the incision
is extended on to the hard palate, exposing the posterior
pharyngeal wall. This is incised in the midline, exposing
the lower third of the clivus and cervical spine to the level
of the second cervical vertebra. The lower third of the
clivus, arch of the atlas, odontoid, and part of C-2 are
removed to expose the dura mater. The tumor then can
be completely removed using magnification techniques.
At closure, the dura will need to be grafted using Lyo-
dura and surgical or fibrin glue when necessary; the pha-
ryngeal wall is usually closed in two layers with Vicryl.

148 / CHAPTER8
Prolonged continuous use of a lumbar subaraclmoid
drain is often necessary during the immediate postopera-
tive period.
Tentorial M eningiomas
Tentorial meningiomas may be above the tentorium.
below the tentoriurn, or both above and below. It is neces-
sary preoperatively to make a precise determination of
the site of origin of the tumor by CT scan and angiogra—
phy. Generally, the supratentorial operative approach
allows better visualization of the tumor, facilitates resec-
tion of the infiltrated portion of the tentorium, and per-
mits total excision in one stage. The infratentorial route
should be reserved for tumors with a posterior attach-
ment. When the transverse sinus is involved, a combined
supratentorial and infratentorial approach is pre—
ferred (263).
Lateral Ventricle Meningiomas
A rneningiorna ofthe lateral ventricle will usually arise
from the area of the trigone or atrium of the ventricle
and will dilate the temporal horn because of the obstruc-
tion to CSF ﬂow it produces (264).
A temporal craniotomy is used, with a cortical inci-
sion rnade in the middle third of the middle temporal
gyrus. The posterior third of the superior frontal gyrus
and the suprarnarginal gyrus must be avoided, especially
in the dominant hemisphere. The cortex and arachnoid
are coagulated and the white mater incised down to the
ependyma of the lateral ventricle. Bipolar coagulation is
used to divide the choroid plexus. The tumor is exposed
but must not be pulled out, for the important anterior
and posterior choroid arteries feeding the tumor will be
torn. Rather, the tumor must be elevated step by step,
exposing the vessels over the medial surface of the tu-
mor, or piecemeal decompression must be done to allow
coagulation of feeding vessels at the tumor margin.
Fixed Lelya retractors are essential during this often ine-
ticulous operation, so as not to unduly enlarge the corti-
cal incision. It is essential not to lose control of medial
arteries and veins as they may be impossible to see until
the tumor is completely removed. The ventricles should
be carefully and gently irrigated, looking for any source
of bleeding, especially from the tela choroidea. Dural
closure must be water—tight.
Outcome
The outcome for patients with meningiomas should
be excellent with few exceptions. With CT or MRI scan-
ning available, these lesions should be diagnosed earlier
while still small in size. This is especially true in patients
who have had a seizure or have experienced progressive
visual loss (Table 1). If light perception is lost before
TABLE 1 . The Medical College of Virginia series of patients with intracranial meningiomas compressing the optic nerve
Pre—Op Post—Op
Duration VA Optic pallor VA CT
# Age/sex symptoms OD“ OSC OD OS OD OS Diagnostic
1 64 F 1 5 years 20/40 NLP -3 +9 20/20 NLP f
2 63 M 6 months 20/800 HM — - 20/20 20/25 +
3 59 M 1 year 20/40 HM — — 20/20 20/200 +
4 51 M 15months ‘ 20/400 _“ tr *3 20/20 +
5 31 F 3 years NLP 20/70 + tr NLP 20/20 +
6 71 F 15years * 20/70 — tr ‘ 20/400 +
7 23 F 3-4 months * NLP — + * NhP +
8 43 F 1 4years 20/200 + — 20/20 , +
9 29 F 9 months CF“ + tr 20/50 , +
10 54 F 6 years HM‘ + — NLP +
1 1 50 M 2 years NLP‘ + — NLP i: +
12 40 F 1 year HM + — 20/400 +
8 VA = visual acuity
"OD = right eye
°OS = left eye
— = negative or absent
6 + = positive
‘tr = trace
9 * = visual acuity 20/30 or better pre— and postoperatively
“ CF = count fingers
‘ HM = hand motion
7 NLP = no light perception

operation, it will not be regained postoperatively. Yet
long periods, often over years, of progressive and severe
visual loss are not incompatible with extraordinary post-
operative visual recovery. It appears that the amount of
vision remaining, not the duration of visual loss prior to
operation, determines the postoperative result, in addi-
tion to the technical expertise of the surgeon (265).
In the series ofpatients with intracranial meningiomas
compressing the optic nerve (see Table 1), by the time of
examination, severe loss of visual acuity was present in
nearly every patient. All patients had dyschromatopsia
demonstrable by color—plate testing, and many had an
afferent pupillary defect with the swinging ﬂashlight test
for optic nerve dysfunction. Definite optic pallor was
observed in 8 of 16 affected eyes. Visual field defects
included a bitemporal depression in five patients, monoc-
ular suppression in five patients, a binasal defect in one
patient, and an incongruous homonymous defect in an-
other patient. Limited gaze of the ocular muscles and
mild proptosis of one eye occurred only in the two pa-
tients with sphenoid wing meningiomas.
Postoperatively, visual acuity improved in 9 of 16 af-
fected eyes (56%), remained the same in 6 of 16 (37%),
and was worse in one patient (#6). Two of four patients
with bilateral visual loss had improvement of visual
acuity in both eyes. A better visual acuity was obtained
in two of eight eyes with definite optic pallor and in two
of four eyes with a trace of paleness of the optic discs.
Visual field deﬁcits distinctly improved in four patients.
It is unfair to compare the results of meningioma sur-
gery done today with those done decades ago by noted
neurosurgeons such as Gushing and Olivecrona. During
nearly all of Cushing's career, only one or two units of
blood could be given as a transfusion, and the heino-
static electrocautery did not become available until 1927
when it was first used for a craniotomy by Gushing. No
discussion of meningiomas would be complete without
acknowledging one of the classic monographs of medi-
cine. In 1915, Harvey Gushing and Louis Eisenhardt be-
gan a meticulous and scholarly study of meningiomas
which resulted in the monograph, M eningiomas: Their
Classiﬁcation, Regional Behavior, Life History and Sur-
gical End Results, published in 1938. This remains the
landmark publication on meningiomas. The case histo-
ries and operative drawings are without equal (9).
Future Treatment
Technical advances continue. The ultrasonic surgical
aspirator allows safe removal of the tumor parenchyma
and spares the vascular supply. This is a very useful in-
strument for tumor operations. The surgical laser is be-
ing increasingly applied to brain tumor operations. A
tumor can be incised, excised, or evaporated by a laser.
There is no doubt lasers will have adjunctive roles in
BRAIN TUMORS ° ° ' 149
most operations for brain tumors, particularly menin-
giomas. The higher incidence of meningiomas in women
compared with men, and the rapidly progressive course
of these tumors in some pregnant patients, suggest that
hormones may be involved in the biology of this tumor.
Indeed, Donnell, Meyer, and Donegan have reported a
high concentration of estrogen—receptor protein in some
meningiomas (266). Olson, Beck, Schlechte, and Loh
have reported that hormonal manipulation of meningio-
mas in vitro by tamoxifen stimulated growth in one in-
stance, but the synthetic antiprogestetone RU486 inhib-
ited rneningiorna growth to some degree (267). Further
research on steroid hormone receptors will be necessary
for developing hormonal therapy for adjuvant therapy
for humans with recurrent or unresectable meningi-
omas.
ACOUSTIC NEUROMAS
Incident
Schwannomas are relatively common tumors corn-
prising 8 to 10 percent of all primary intracranial neo-
plasms. Schwannomas generally originate from sensory
nerves, although they have been found in virtually every
site intracranially. including intracerebrally.
The neuroma of the eighth cranial nerve is known by
many names, such as schwannoma of the eighth nerve,
acoustic neuroma, acoustic neurinoma, peripheral
glioma, cerebellopontine angle tumor, and pen neural fi-
broblastoma. In serial sections of unselected temporal
bones, the tumor has been found in its very early stage of
growth in 1 to 2 percent of specimens. The tumor is
usually unilateral, but may be bilateral in type II von
Recklinghausen's disease. Neurosurgeons and otological
surgeons tend to use different surgical approaches to
acoustic neuromas. Otological surgeons, who usually ex-
amine patients with hearing deficits who present early,
frequently diagnose the tumor when the tumor is very
small, less than 1 cm in diameter. Otological surgeons
prefer to remove the small tumors via a translabyrinth—
ine approach. This approach has a high success rate in
preserving brainstem and seventh nerve function, but
destroys the organs ofhearing. Thus, any remaining pre-
operative hearing in the affected ear cannot be preserved
or improved by the translabyrinthine operation. Neuro-
surgeons, on the other hand, who more frequently ini-
tially evaluate patients with cerebellopontine symptoms
and signs caused by larger tumors, prefer the suboccipi—
tal transmeatal approach. This approach allows direct
visualization of the vital brainstem structures and allows
preservation of not only the seventh cranial nerve but
potentially the cochlear division of the eighth cranial
nerve as well.

150 / CHAPTER8
Symptoms and Signs
Since these tumors primarily arise from the vestibular
components of the eighth nerve near Scarpa's ganglion
in the internal auditory canal, the vestibular and audi-
tory fibers are usually involved early (268). Auditory
symptoms are the earliest and most striking symptoms
and appear in the form of tinnitus and progressive loss of
hearing. Tinnitus usually precedes dizziness. Vestibular
symptoms are less pronounced and consist of mild per-
sistent episodes of objective or subjective vertigo. The
tumor may become extremely large before seventh cra-
nial nerve symptoms appear. As the tumor grows out of
the porus acousticus and into the cerebellopontine angle,
the fifth cranial nerve or the descending tract of the fifth
nerve in the brainstem becomes compressed by direct
pressure on the brainstem, producing numbness of the
ipsilateral face.
As the tumor enlarges, compression of the adjacent
cerebellar hemisphere or the cerebellar peduncle pro-
duces ataxia, vertigo, and dysmetria of the ipsilateral ex-
tremities. Initial gait ataxia may progress to a tendency
to fall to the side of the tumor. Nystagmus toward the
side of the lesion develops. Further increase in size dis-
places the brainstem, as well as cranial nerves IX, X, and
XI. There may be difficulty in swallowing and talking,
with slurred or nasal speech.
The dislocation of the pons may cause obstruction of
the fourth ventricle, or the tumor may grow upward
through the incisura of the tentorium, obstructing the
ﬂow of spinal ﬂuid and leading to increased pressure sec-
ondary to hydrocephalus. This will cause headaches and
vomiting. Very rarely, a patient will have localized pain
in the retromastoid area.
The very small tumors are still rarely diagnosed be-
cause of the mild early symptomatology. Initial audio-
logical testing is positive for a retrocochlear lesion in
only about one—half of patients harboring a small tumor.
As the tumor becomes larger, a sensorineural hearing
loss can be documented by audiometry and absent calo-
ric responses on the affected side. Caloric testing has
been improved by use of the electronystagmogram.
Hearing loss can frequently be characterized as retro-
cochlear by finding impaired speech discrimination,
type II and type IV Bekesy audiometric responses, and
an absence of recruitment as evidenced by a low, short-
increment sensitivity index (SISI) score. These tests are
being replaced by brainstem evoked—response audiome-
try (269) which, along with MRI, will reveal even the
smallest tumors. MRI distinctly shows the relationship
of the tumor to the adjacent seventh cranial nerve.
The involvement of the seventh cranial nerve pro-
duces a peripheral facial nerve palsy and hypesthesia of
the posterior aspect of the external auditory canal. The
latter has been found in up to 95 percent of cases and is
regarded as a sensitive indicator of facial nerve involve-
ment. As the fifth cranial nerve becomes involved, there
will be loss of the corneal reﬂex and later hypesthesia
over all three divisions of the trigeminal nerve.
The involvement of the cerebellum and peduncle is
recognized by mild ataxia or dysmetria on the ipsilateral
side. Reﬂex changes and weakness of the ipsilateral arm
and leg occur when the tumor is veryiarge.
Pathology
The neuroma of the eighth nerve develops primarily
from vestibular branches in the internal auditory canal
near Scarpa's ganglion (268). The tumors are round, ir-
regularly encapsulated, and very firm in consistency.
They measure from 1 cm to 4 cm when they finally fill
the cerebellopontine angle. They appear grossly as dark
yellow or brown in color, with areas of degeneration and
cysts.
Microscopically, there are firm areas and irregular
softer yellow areas of fatty degeneration. The firm area
consists of elongated Schwann—cell nuclei, arranged in
rows producing typical palisading. Collagen is deposited
in uniform sheets between the cells. In the softer areas,
there are foamy cells sometimes referred to as pseudo-
xanthoma cells.
In type II von Recklinghausen's disease, the acoustic
neuromas are likely to be bilateral and associated with
optic nerve gliomas, intracranial gliomas, and meningio—
mas. The skin may show cafe—au—lait pigmentation, sub-
cutaneous lipomas, and peripheral neuromas. The
eighth nerve tumor in von Recklinghausen's disease,
even when small, is very unlikely to be removed with
preservation of hearing.
Diagnostic Tests
The definitive tests are radiological. Plain x—rays with
Stenver's views and tomography will reveal erosion of
the internal auditory canal in over 75 percent of cases.
The density of the petrous bone on CT may obscure the
smaller tumors in the porus acusticus (270). Therefore,
enhanced MRI of the posterior fossa is now the best sin-
gle radiologic test to define the tumor and its relationship
to the adjacent cranial nerves and brainstem (Fig. 8).
Multiplaner imaging capability undiminished by bony
artifacts represents the major advantage of MRI in the
posterior fossa region. Acoustic nerve tumors and cere-
bellopontine angle (CPA) meningiomas both exhibit low
signal intensity on T,—weighted images, but may be dif-
ferentiated by location. A CPA meningioma usually can
be seen as separate from the vestibular nerve complex,
whereas the epicenter of an acoustic nerve tumor is lo-
cated at that complex.

R
FIG. 8. Right acoustic neuroma. MRI details relationship of
tumor to the seventh cranial nerve (arrow).
Operation
Total removal of acoustic neuromas is now possible,
especially with early diagnosis and rnicrosurgical tech-
niques. Not only can surgeons usually preserve the func-
tion of the seventh nerve in patients with small acoustic
neuromas, but at times the cochlear nerve can be pre-
served as well, preserving or restoring useful hearing.
The patient can be operated on in the sitting position,
or a reclining or supine position with rotation of the
head. A linear scalp incision is made on the symptomatic
side over the occipital bone. A unilateral retromastoid
craniectomy is carried out, removing bone posterior to
the sigmoid sinus. The basic approach to the tumor by
the suboccipital transmeatal approach has been outlined
by Rand and Kurze (271). The facial nerve is identified
and separated from the tumor in the auditory canal, and
the bulk of the tumor is decompressed. From the lateral
aspect resection proceeds from the posterior direction
down to the pons. Cranial nerves IX, X, and XI are care-
fully identified. Branches of the anterior inferior cerebel-
lar artery are also identified and spared. Superior aspects
of the tumor are resected down to the pons, identifying
the fifth cranial nerve superiorly. The remaining tumor
is dissected clear of the facial nerve. Skillful surgeons
with experience using modern magnification techniques
can usually spare cranial nerve VII. A stimulator at the
lowest possible setting applied at the brainstem origin of
the facial nerve will produce a facial twitch if the nerve is
intact at the end of the operation. If this nerve is sec-
tioned during the operation, it may be repaired at that
BRAIN TUMORS / 151
time. Since the nerve has been stretched by the tumor, it
is often possible to reanastomose the nerve using rnicro—
suturing techniques. If this cannot be done, then at a
second operation, a hypoglossal—facial anastomosis can
be done. Some surgeons prefer to use either the phrenic
or accessory nerve for the anastomosis.
If the tumor is extremely large, it may be beneficial to
do a two—stage operation as recormnended by Sheptak
and Jannetta (272). At the first operation, an attempt is
made to remove at least 50 to 75 percent of the tumor
and the seventh cranial nerve is tagged. Tumor rernain—
ing after the first operation gradually decompresses out
of the pons and comes to lie laterally against the petrous
bone. Upon reoperation 10 to 14 days after the first oper-
ation, tumor is usually found to fill the void left by the
first operation. At the second operation, it may be easier
to identify the arachnoid plane between the brainstem
and the tumor, and dissection is more easily carried out
without disturbing the patient's vital signs during the
operation.
Outcome
In the series reported by Sheptak and J annetta, of 25
patients with acoustic neuromas who underwent sur-
gery, 78 percent had a good result, returning to normal
activity or full—tirne employment. Anatomic continuity
of the facial nerve was preserved in 74 percent of pa-
tients, rnost of whom recovered facial function (272).
When the facial nerve remains anatomically intact at
operation, it may take 2 to 14 months for satisfactory
facial movement to return.
The most frequent immediate postoperative cornpli—
cation is CSF circulatory problems and has been re-
ported in up to 35 percent of operated patients
(273,274). A CSF leak at the operative site may require
temporary lumbar drainage of CSF. If there is a transient
fifth and seventh cranial nerve paresis, then a temporary
tarsorrhaphy should be done for prevention of potential
corneal irritation.
Recurrence is a problem of incomplete removal. In
MacCarty's series, 15 of 132 patients had subtotal exci-
sions and, of these, five needed reoperation for recur-
rence (275). In a series of 30 patients reported by Oje—
rnann, 10 tumors were totally removed. Three of the
tumors which were incompletely resected recurred
within 15 to 24 months after the initial operation (274).
Patients with neurofibromatosis who have bilateral
acoustic neuromas with deafness in one or both ears will
most certainly need speech and hearing training includ-
ing lip reading, as attempts to remove these tumors bilat-
erally will nearly always result in deafness. Acoustic neu-
romas are more frequent in women and may have a
rapidly progressive clinical course in pregnant women.
Neuroma of the acoustic nerve is the other intracranial

152 / CHAPTERS
tumor besides meningioma in which estrogen receptors
have been demonstrated (276).
CRANIOPHARYNGIOMAS
Incidence
Craniopharyngiomas account for approximately 4
percent of intracranial tumors, with 0.5 to 2 percent of
new cases/million population occurring each year. Al-
though one—half of the total cases ofCraniopha1yngiomas
occur in adults, Craniopharyngiomas account for a
greater percentage of tumors of children: 5 to 13 percent
of all intracranial neoplasms of childhood, with a peak
incidence from 6 to 15 years (277). Craniopharyngiomas
were the most common supratentorial tumor of child-
hood in Matson's tumor series (277). There are marked
differences’ in clinical presentation, radiological charac-
teristics, and postoperative outcome between children
and adults.
Symptoms and Signs
Children with a craniopharyngioma usually present
with headaches, vomiting, or visual loss, and psychologi-
cal changes. Diabetes insipidus is rare. Adults usually
present with endocrinological disturbances and visual
field defects.
Examination may reveal Visual field defects and often
bitemporal hemianopsia. About 30 percent of children
are found to have papilledema. Small stature is noted in
children. Adults will have endocrine disturbances such
as amenorrhea or loss of libido.
Pathology
These tumors are epithelial in origin and partly cystic
in nature, containing cholesterol crystals and deposits of
calcium. The histological pattern consists of nests of
complex strands of epithelial cells, supported by a vari-
able amount of loose connective tissue stroma/‘Since the
anatomical structures in the suprasellar region are nor-
mally devoid of epithelial cells such as those seen in Cra-
niopharyngiomas, the nature and source of these cells
have been the subject ofextensive investigation. The pap-
illary histological characteristics of the tumors often
have keratin nodule formations, cholesterol clefts, for-
eign body giant cells, adamantinous elements, and squa-
mous epithelium.
Craniopharyngiomas are now generally considered to
arise either from ectopic embryonic cell rests of enamel
organs, or from residual metaplastic squamous epithe-
lium found in the adenophypophysis and anterior infun—
dibuluin. There is evidence for two distinct craniopha-
ryngioma variants, a squamous papillary type and a
classic adamantinous type.
These tumors have a benign microscopic appearance
which belies their malignant clinical behavior, especially—
in childhood. Although usually apparently well circu1n—
scribed and extracerebral in location, they often show
extension into neighboring brain tissue evoking a Van'-
able degree of glial reaction. Islets of tumor cells may be
found in the hypothalamus and in the walls of the third
ventricle. Although only a few Craniopharyngiomas are
found in the third ventricle, most grow around and into
adjacent structures, such as the carotid and anterior cere-
bral aiteries, the optic nerves and chiasm, as well as the
hypothalamus, and total operative removal can be ex-
tremely difficult if not impossible, even with modern
neurosurgical techniques.
Diagnostic Studies
Plain x—rays are helpful in children, as approximately
70 percent of cases of craniopharyngioma will have intra-
cranial calcification in an area of an abnormal sella tur-
cica. Craniopharyngioma is the most common tumor to
produce recognizable suprasellar calciﬁcation. Signs of
intracranial hypertension, such as sprung cranial su-
tures, may be seen on plain x—ray as well. Calciﬁcation is
less common in adults with a cianiophaiyngioma. CT
and/or MRI scanning is the initial diagnostic test of
choice and, in addition to a well—circumscribed suprasel-
lar tumor which may have attenuation values of both
cyst and calcium, CT or MRI will reveal any hydrocepha-
lus caused by the tumor.
Operation
Patients with a craniopharyngioma can be treated by
one of four modalities: (1) gross total tumor excision, (2)
incomplete tumor removal with radiotherapy, (3) in-
complete tumor removal without radiotherapy, and (4)
cyst evacuation through a burr hole followed by radio-
therapy, repeated cyst aspiration, or installation of radio-
active substances into the cyst.
The location and configuration of the tumor inﬂu-
ences the surgical approach. Wholly intrasellar tumors
can be safely removed by the transphenoidal route. Tu-
mors extending under the temporal lobe are best ap-
proached by a temporal route. The majority of Cranio-
pharyngiomas are located beneath the chiasm and
extend up into the hypothalamus and third ventricle,
down between the clivus and brainstem, and also into
the sella. With this location, some surgeons recommend
an approach along the sphenoid ridge, others advocate a
subfrontal approach, and still others approach the tumor
obliquely over the roof of the orbit or along the
falx (278).

Tumor removal may be carried out through a sub-
frontal exposure according to techniques outlined by
Matson and Crigler (277). These authors were able to
totally remove 44 tumors from a group of 74 children
with craniopharyngiomas, without operative mortality
in the 40 patients who had a primary operation only.
Secondary or tertiary operations were associated with in-
creased postoperative morbidity and mortality.
Patterson and Danylevich have described a transcra-
nial approach through the lamina terminalis and sphe-
noid sinus for removal of craniopharyngiomas (279). In
this approach, a small, low unilateral bone ﬂap is made
on the right side (particularly convenient for a right-
handed surgeon) above the orbit, so that it spans the
distance between the falx and temporal line, just above
the orbital ridge. A small strip of 1 cm of the undersur-
face of the frontal lobe is removed to facilitate exposure
of the lamina terminalis behind the optic chiasm. The
tuberculum sellae is removed, the sellar contents visual-
ized, and the lamina terminalis is exposed between the
optic tracts. The tumor is removed by pushing pieces
down and away from the optic chiasm and hypothala-
mus, and toward the sphenoid sinus from where the tu-
mor pieces are extracted. In this method, tumor on the
hypothalamus is removed under direct vision. A unilat-
eral pterional craniotomy is used by many surgeons as it
allows dissection in the parachiasmal spaces.
Regardless of the approach, special care must be taken
not to injure the frontal lobes, optic nerves, chiasm. op-
tic tracts, hypothalamus, or adjacent vasculature. The
risks of operation are real, but recent advances in magni-
fication techniques allow radical, if not complete, re-
moval of these tumors, sparing the all important infun-
dibulurn and pituitary stalk.
Outcome
Often the surgeon, even with magnification tech-
niques, is confident of total tumor removal at the end of
the operation, only to find that the follow-up CT or MRI
of the brain reveals some tumor, or that the tumor recurs
(280). In many instances this event is unavoidable since
the tumor is not nearly so discrete from brain tissue as
most surgeons believe. Bartlett has stated that total re-
moval of a craniopharyngioma is impossible (281).
Kempe has stated emphatically that the capsule of a
craniopharyngioma is closely attached to the hypothala-
mus, and that attempting complete removal of the tu-
mor invariably leads to infarction of the hypothalamus
(248). Ghatak, Hirano, and Zimmerman have clearly
demonstrated the local invasiveness of the tumor (282).
Thus, the tumor is not only malignant by location but by
histology as well, as it can actually infiltrate the brain
with nests of cells making operative removal impossible.
This fact is well established in the literature, but too of-
BRAIN TUMORS
ten ignored in the actual patient with a craniophanim-
giorna, especially at the time of initial diagnosis and
operation.
Bloom reports 5- and 10-year survival rates of 76 and
61 percent, respectively, for patients treated with opera-
tion and conventional radiation therapy at the Royal
Marsden Hospital (283). At the New York Hospital, par-
tial removal of craniopharyngiomas resulted in a recur-
rence rate of 72 percent within 5 years without radiation
therapy, and 41 percent when 3,000 to 4,500 rads were
given following operation (279). These are unsatisfac-
tory results when one considers craniopharyngiomas to
be potentially a biologically benign tumor, although
usually malignant by location. The major problems to
overcome are damage to the frontal, temporal, or hypo-
thalamic areas of the brain. Tumor recurrence is a major
problem, and usually occurs because pieces of the tumor
are left in the hypothalamus. Craniopharygiomas that
are adherent to the hypothalamus in the region of the
tuber cinereum cannot be removed totally with preserva-
tion of the pituitary stalk and with the patient being free
of diabetes insipidus.
When the goal of complete or radical removal of this
tumor is not achieved, the best method of treatment for
the patient is unclear. At the Hospital for Sick Children.
London, even radical removal was associated with at
least 25 percent recurrence (284). It is usually the larger
tumors, greater than 3 cm at initial diagnosis, that are
unable to be removed and thus deserve attention for fur-
ther therapy.
Preliminary observations suggest that radiotherapy
offers an additional therapeutic modality for patients
with residual postoperative tumor. In Shapiro, Till, and
Grant's report, seven patients were treated by inco1n-
plete removal and deep radiotherapy of 4,000 to 5,500
rads without symptomatic recurrence (284).
If the tumor is cystic, or the recurrence is cystic as it
often may be, then an Ommaya reservoir should be
placed for easy repeated aspiration. Also, this can be
used to instill radioactive substances into the cystic tu-
mor. We and others have used colloidal chromic phos-
phate (colloidal 32P) intracystic injections successfully to
sclerose the secreting tumor lining and improve the clini-
cal condition of the patient (285-287). We have shown
an in vitro destruction of craniopharyngioma cells by 32P
(287). A dose of l mCi colloidal 32P per injection will not
injure the optic or oculomotor nerves because ofthe lim-
ited penetration (approximately 1 mm) of the beta-ra-
diation of 32F, unless the cyst is very small and the wall
less than 0.5 mm in thickness.
Hoffman and coworkers suggest withholding radio-
therapy in cases of incomplete excision until there is tu-
mor recurrence (288). Certainly, considering the long-
terrn effects of radiotherapy, it should not be
administered if only a small amount of tumor remains
on the internal carotid artery or hypothalamus. If a large

154 / CHAPTERS
amount of tumor remains, radiotherapy to 5,000 rads
can be administered to the tumor area only. A cystic
recurrence of the tumor can be treated by aspira-
tion along with the injection of 32P or 198Au into the
cyst (285).
In children, it has been observed that, following re-
moval of a craniopharyngioma, normal growth may
continue despite lack of growth hormone secretion or
growth hormone therapy. If growth becomes retarded,
exogenous growth hormone can be administered. Fol-
lowing attempts at complete removal, some children will
become very obese or have diabetes insipidus requiring
strict endocrine control.
Future Treatment
Bullard and Signer reported a major breakthrough in
the heterotransplantation of human craniopharyngioma
in athymic "nude" mice (289). Thus, there is now a use-
ful animal model to study the natural history and cell
biology of this tumor.
PRIMARY CENTRAL NERVOUS SYSTEM
LYMPHOMAS
Incidence
Primary central nervous system (CNS) lymphomas
have in the past constituted a rare group of neoplasms.
These are non—Hodgkin's lymphomas, mostly of B—cell
origin. They include reticulum—cell sarcomas, microglio—
rnas, and histiocytic lymphomas. These tumors initially
represented less than 1 percent of all primary brain tu-
mors. In the past 10 years, however, the incidence has
tripled in the nonimmunosuppressed population. By
1991. the tumor will be the most common neurological
neoplasm by virtue of the increase in its sporadic occur-
rence and in the acquired immunodeficiency syndrome
(AIDS) population. Three percent of AIDS patients will
develop this tumor either prior to AIDS diagnosis, or
during their subsequent course. Immunological studies
have also suggested a role for Epstein—Barr virus in the
production of lymphomas.
The first description of tumors classiﬁed as non—Hodg—
kin's lymphoma of the CNS (NHL—CNS) labeled the tu-
mors "perithelial sarcomas," reﬂecting their perivascu—
lar location. There was a resemblance between these
brain neoplasms and those tumors of lymph node origin
which had been termed "reticulum cell sarcomas"
(RCS). American authors favored the term "reticulum
c e l l sarcoma," and European authors preferred the term
"microglioma." Other authors considered these tumors
to be two separate but related tumor types. This entire
controversy has become irrelevant, as these tumors are
in fact lymphomas.
The modem classification of non—Hodgkin's lympho-
mas emerged from the separation of systemic lympho-
mas into histological groups with differing prognoses
and the realization that most non—Hodgkin's lympho-
mas were cornposed of neoplastic B—lymphocytes. The
application of increasingly sophisticated immunological
and molecular genetic methods to lymphoma diagnosis
and classification has given rise to a series of classifica-
tion systems, culminating in the International Working
Formulation sponsored by the National Cancer Insti-
tute.
Diagnostic Studies
Of the roughly 24,000 individuals in the United States
who each year develop NHL, between 2 and 10 percent
will develop neurological involvement. There is a slight
male preponderance at all ages, with a median age at
occurrence of 55 years. Three populations are at risk of
developing NHL—CNS: transplant recipients, patients
with AIDS, and those with congenital immunodeficien-
cies. The patients with NHL—CNS present with four dis-
tinct proﬁles: ( 1) solitary or multiple discrete intracranial
nodules, (2) diffuse meningeal or periventricular lesions,
(3) uveal or vitreous deposits (uveitis/vitritis), and (4)
localized intradural spinal cord masses. A febrile upper
respiratory or gastrointestinal illness may precede the ini-
tial neurological symptoms, which frequently are person-
ality changes. These neurological difficulties are similar
to those seen in multiple sclerosis, and in encephalitis of
viral, fungal or parasitic origin. The eye involvement by
lymphoma often accelerates the development of clini-
cally evident deposits in the brain. Eye symptoms such
as obscured, cloudy or blurred vision, or altered visual
acuity accompany lymphoma involving the posterior
segment of the eye, including the vitreous, choroid, and
retina.
Both contrast—enhanced CT and MRI provide delin-
eation of the number and extent of NHL—CNS lesions
within the brain parenchyma. Ten percent of these le-
sions are detectable on contrast CT as hyperdense
deposits within the subcortical white matter, often in
proximity to the ventricular system. Calcification, hem-
orrhage, or cyst formation is uncommon, and suggests
other lesions. The injection of single or double contrast
results in delineation of lesions in over 90 percent of
patients with Jymphomas. CT and MRI usually fail to
detect subaraclmoid or vitreal NHL—CNS.
The tumor staging done in this disorder is based on
enhanced CT scanning, CSF examination (in the ab-
sence of intracranial hypertension), and slit—lamp eye
evaluation. As NHL—CNS is a restricted neurological ail-
ment, there is little reason to perform CT scans of the
chest or abdomen, bone marrow biopsy, or surgical ex-
ploration of the abdomen. Stereotactic biopsy may be

necessary at times when the above studies fail to give a
histological or immunohistochemical diagnosis.
Treatment
The initial treatment is corticosteroids, which usually
provides a dramatic but short—lived clinical improve-
ment and often complete regression of the lesions. This
responsiveness represents true glucocorticoid cytotoxic-
4ty for lymphoid cells. Radiation therapy clearly pro-
longs survival, and adjuvant chemotherapy trials are un-
derway in at least five centers in the United States.
METASTATIC INTRACRANIAL TUMORS
Incidence
The incidence of metastatic tumor is increasing, pri-
marily caused by two factors: (1) improved length ofsur—
vival of patients with cancer, thus increased exposure
time for metastases, and (2) the diagnostic acumen for
single or multiple metastases has been greatly enhanced
by CT and MRI scanning. Also, although unproven in
humans, there is experimental evidence that some che-
motherapeutic agents given for systemic cancer may
produce transient defects in the normal blood—brain
barrier, thus potentially permitting CNS seeding of these
systemic tumors (3).
Brain metastases are the immediate cause of death in
many patients with cancer. At Memorial Hospital in
New York, autopsies of patients who died from systemic
cancer disclosed that 12 percent had brain metastasis, of
which 40 percent were solitary tumors (290). With the
increasing number of these patients, the controversial
aspects of their care must be clarified. Properly man-
aged, many of these patients can be greatly helped and
can enjoy a worthwhile life. In this section, it is our in-
tent to present the neurosurgeon's viewpoint and role in
the management of these patients.
Symptoms and Signs
The symptoms and signs of metastatic brain tumors
are similar to those of other expanding intracranial le-
sions. The tumor may produce a generalized increase in
intracranial pressure, as well as local effects by compres-
sion or destruction of brain tissue in the area of tumor
growth. The generalized increase in intracranial pressure
will result in headache, nausea, and vomiting. Headache
is the single most common presenting symptom of cere-
bral metastases, but is present in only about 50 percent
of cases. The headaches are usually caused by increased
intracranial pressure and are present in the morning
upon awakening. Mental status changes and weakness of
BRAIN TUMORS / 155
an extremity may be important symptoms. Seizures oc-
cur in only about 15 percent of cases, but especially in
the patients with leptomeningeal metastases. Abrupt on-
set of neurological symptoms suggestive of a stroke may
occur from vessel occlusion by tumor cells or by hemor-
rhage into the tumor, brain, or subarachnoid space. Pa-
tients with melanoma, choriocarcinoma, and with de-
creased platelet counts secondary to chemotherapy may
present with intracranial bleeding.
The examination will reveal papilledema if there has
been a chronic increase in ICP. Mental changes may be
related to the specific area of the brain, but usually there
is a defect in cognitive functioning. Hemiparesis and re-
ﬂex changes are frequently revealed by examination espe-
cially when the tumor involves the motor cortex or the
internal capsule.
Pathology
The most common sources of metastases to the brain
are tumors of the lung, breast, and kidney, and rnalig—
nant melanoma. Tumors of the gastrointestinal tract,
thyroid, uterus, ovary, pancreas, and prostate, and sarco-
mas infrequently metastasize to the brain. About 50 per-
cent of brain melastases originate from malignancies in
the lung or breast. There is an extremely high incidence
of CNS metastases from small—cell bronchogenic carci-
noma, and the incidence is increased to 80 percent in
patients surviving two years after diagnosis (263). In pa-
tients in whom the primary tumor is initially unknown,
more than one—half are subsequently found to have
bronchogenic carcinoma. Metastases to the brain may
be both leptomeningeal and intracerebral.
The route of spread of metastasis to the CNS is usually
hematogenous, although occasionally the tumor spreads
by direct extension through the bone or via the subarach-
noid space, as in leptomeningeal invasion.
About 75 percent of intracranial tumor deposits are
located within the brain parenchyma, frequently at the
junction of white and gray matter. In some series, a pre-
dominance of parenchymal metastasis has been ob-
served in the distribution of the middle cerebral artery
which has been explained on the basis of laminar ﬂow
(291,292). The cerebellum is another frequent site for
tumor deposits.
Brain metastasis from solid tumors is solitary in about
50 to 65 percent of cases when the diagnosis is made
during life. In autopsy series, the incidence of solitary
metastasis drops to 25 to 40 percent. The lesions are
generally soft, nodular, circumscribed masses, often with
central necrosis. They vary in size, with even the smallest
lesion being associated with severe white—matter edema
of the ipsilateral hemisphere. In addition to solid rneta—
static lesions, leukemia and lymphomas are also a major
disease category that invades the CNS. These hemato-

156 / CHAPTER8
logical malignancies usually invade the leptomeninges in
a diffuse or multifocal manner.
There is a wide variability in the interval between the
clinical appearance of the primary cancer and that of the
cerebral metastasis. The cerebral metastasis may be the
first manifestation of a systemic cancer. The symptoms
and findings of cerebral metastasis may appear at the
time of initial evaluation of systemic cancer in the course
of screening studies or many years after the initial diag-
nosis of cancer. The time interval tends to be a function
of the tissue of origin of the metastatic tumor. The aver-
age interval between the diagnosis of lung carcinoma
and the development of brain metastasis is four months,
whereas the interval for breast cancer averages three
years. An excision of a cerebral metastasis may also be
followed by a long latent interval of months or rarely
even years before the primary cancer, which is usually
bronchogenic. is evident.
Vasogenic edema, which predominantly involves the
white matter, is due to leakage of serum proteins and
ﬂuid through blood—vessel walls. This type of edema is
seen with metastatic carcinoma even when the tumor is
very small. Metastatic neoplasms within the brain are
characterized by an absence of a blood—brain barrier to
protein. As demonstrated by standard radionuclides
used for clinical diagnosis, the abnormal permeability to
protein—bound tracers is related to defective capillary en-
dothelium (293). These defective capillaries are found in
the tumor and not surrounding edematous brain. The
presence of defective capillaries probably is sufficient to
explain the associated brain edema. These blood vessels
provide a ready egress for the serum into the extracellu-
lar space of the brain.
In a prospective study by Galicich, Sundareson, Arbit,
and Passe of 33 patients with a solitary brain metastasis,
the second most common cancer to lung cancer was inel-
anoma (294), Tn a series of 1,341 patients with histologi-
cally proven malignant melanoma seen at Duke Univer-
sity Medical Center frorn 1968 to 1978, 107 patients
developed central nervous system metastasis (295). Male
patients, patients with invasive primary lesions as rnea—
sured by Clark's system, and patients with primary le-
sions of the head, neck, or oral mucosa had a higher
incidence of CNS metastasis. A single CNS metastasis
was seen in 48.8 percent ofpatients, and in 22 percent of
the patients the CNS was the only site of metastasis.
Melanoma occurs in multiple sites in the brain in the
majority of cases (296). An autopsy series reported by
Patel and associates of patients who died with multiple
metastatic melanomas closely detailed the central ner-
vous system involvement (297). The rates of metastasis
were 49 percent for brain, 22 percent for meninges, and
13 percent for medulla and pons. Patel and associates
also correlated autopsy findings with the terminal course
of patients with melanoma. Of 216 patients, 20 percent
died of a CNS complication, second to 39 percent who
died of respiratory failure. Thus, one—fifth ofthe patients
died from complications of brain metastases, primarily
from hemorrhages and increased intracranial pressure.
All patients with primary head and neck melanoma be-
ing evaluated for surgery should have a CT or MRI be-
cause of the higher incidence of CNS metastases, corn-
pared to patients with melanomas of the extremities
(298). Radiation therapy has little to offer patients with
melanoma (299).
Choriocarcinoma is the most malignant of the tumors
of chorionic tissue that arise from fetal tissues and in-
vade the maternal vasculature. The tumor cells rnetasta—
size by way of the vascular system to all organs, predorni—
nantly to the lungs and brain (300). The incidence of
cerebral metastasis from chorioepithelioma is 20 percent
or more (301). Since tumor cells spread by the vascular
system, tumor invasion of the vessel wall produces de-
generation and then dilation into varices or small aneu-
rysms which result in cerebral or subarachnoid hemor-
rhage. Intracerebral hemorrhage is the first sign of
involvement of the central nervous system. At autopsy,
occlusion of a cerebral artery, probably caused by tumor
emboli, is a commonly observed finding. Also, occlusion
of relatively large arteries has been reported and con-
firmed by operation (302).
Diagnostic Studies
Plain skull films are less valuable in evaluating pa-
tients with metastatic tumors for signs of increased intra-
cranial pressure than patients with primary tumors.
Even the calcified pineal gland may not be shifted be-
cause of bilateral or balancing lesions. The skull x—rays
may reveal bone destruction of the calvarium or base,
but the presence of bone metastases may or may not be
associated with an intracranial parenchymal lesion.
CT or MRI is the single most useful diagnostic test, as
each currently can detect 6- to 10-min lesions depending
on density and location (303). CT or MRI will also detect
multiple lesions better than any other known method. In
addition, CT or MRI accurately reveals the amount of
edema surrounding a metastatic lesion and is, therefore,
useful for follow—up in the patient being palliated by ste-
roids. Hydrocephalus associated with posterior fossa le-
sions can be evaluated quickly on CT or MRI.
Cerebral arteriography and lumbar puncture are being
used less in the era of scanning. Arteriography will be
necessary at times when the diagnosis remains unclear or
in preparation for stereotactic biopsy or surgical exci-
sion. Lumbar puncture may be indicated after the pres-
ence of an intracerebral (parenchymatous) mass has
been ruled out by CT or MRI in order to make a definite
diagnosis of meningeal carcinomatosis or fungal or bacte-
rial meningitis. The spinal ﬂuid obtained by lumbar
puncture should always have cytology done for rnalig—

nant cells, as well as careful bacteriological cultures for
rare fungi, such as cryptococcus. Tumor markers such as
carcinoembryonic antigen should be measured as well,
because these markers are useful in diagnosis and ther-
apy (304,305).
Operation
In general, management of the patient with metastatic
carcinoma to the brain is almost always palliative, with
cure being the rare exception. The patient with multiple
or deep cerebral lesions, or the patient whose condition
is generally poor with short life expectancy, is best pal-
liated by steroids and x—ray therapy. Steroids are effective
in reducing the associated cerebral edema and intracra—
nial pressure, thereby usually relieving the headaches.
Radiation therapy and/or chemotherapy may slow tu-
mor growth.
There are definite guidelines for operation. In general,
the metastasis should be solitary and surgically accessi-
ble, although surgical removal is sometimes indicated
for multiple lesions which are easily surgically accessible
or in the same operative exposure. The status of the pri-
mary tumor should also be considered. The primary tu-
mor should have been previously successfully treated
(i.e., by pneumonectomy), or treated in the future so at
least to permit long survival. At times, the intracranial
tumor may be symptomatic or life—threatening while the
primary is quiescent; then the metastasis will require im-
mediate operation. Also, there should not be widespread
metastases throughout the body.
Another indication for operation is when the diagno-
sis is unknown. The primary may be unknown and a
tissue diagnosis may be indicated for future therapeutic
management. Also, a solitary lesion in a patient with
cancer does not necessarily indicate a metastasis. The
differential diagnosis includes brain abscess, hematoma,
cerebral infarct, and another tumor such as a menin-
giorna or glioma.
The operation, with adequate steroid preparation, for
a metastatic tumor should be attended by low morbidity
and mortality. These tumors are usually easily located
beneath the cortical surface by mere visual inspection,
gentle palpation, or needle exploration. The tumor is
usually circumscribed, although not truly encapsulated.
It can be microscopically separated from brain tissue. It
is unclear whether there are microscopic cells remaining
after gross removal, but often in a more silent areas of the
brain, a 2- to 3—mm rind of surrounding brain can be
removed and the tumor bed carefully inspected for re-
maining tumor deposits. In various series, tumor re-
moval has been verified as complete at the operative site
in 58 to 75 percent of cases. Even when tumor removal
appears complete, x—ray therapy is standard adjunctive
postoperative therapy.
BRAIN TUMORS / 157
If a tissue diagnosis is necessary and the patient's con-
dition is poor, then CT— or MRI—guided needle biopsy
can be done. With CT or MRI verification, the needk
can be accurately placed in the tumor and adequate tis-
sue obtained for diagnosis.
Leptomeningeal carcinomatosis has been found in up
to 40 percent of autopsied symptomatic and asyrnptorn—
atic patients with cancer, and may occur with any tumor.
Carcinoma of the breast involves the meninges most fre-
quently. The tumor may occlude the basal cisterns and
spinal meninges, producing a communicating hydro-
cephalus.
The tissue type of the metastasis, if known, should
inﬂuence operation. A tumor that is very radiosensitive,
such as lymphoma, can best be treated by radiotherapy
alone, after stereotactic biopsy, but other tumors such as
a hypernephroma or melanoma, being very radioresis—
tant, should be removed when solitary in the brain.
Outcome
The median survival time for series reported since
1970 of patients with a single metastasis, following oper-
ation alone, is five to six months. Thus, the median sur-
vival statistics of surgery alone are approximately the
same or slightly better than radiation therapy alone. In
RansohofFs series of 100 patients treated by combined
modalities of operation plus radiotherapy and/ or chemo-
therapy, 38 percent survived 1 year and 13 percent sur-
vived beyond 2 years (306). In other studies of patients
with cerebral metastasis from bronchogenic carcinoma.
the median survival was 6 months, but 45 percent
survived longer than a year, and about 30 percent
were syrnpto1n—free neurologically during that time
(l99,307—309).
It thus appears that a combined therapeutic approach
affords superior benefit over any one single treatment
modality alone (310-312). As oncologists improve the
longevity of patients with cancer, neurosurgeons will
need to be extremely aggressive to keep pace in knowl-
edge and techniques of polytherapy so as to give the pa-
tient the best opportunity for quality survival following
cerebral metastasis.
Combination chemotherapy does not control CNS
metastases ofpatients with s1nall—cell bronchogenic carci-
noma. Unfortunately, since metastasis develops in one-
third to one—half of all patients with small—cell cancer,
many advocate prophylactic radiotherapy to the head,
but the efficacy of this approach has not been proven.
REFERENCES
1. Russell DS, Rubinstein LI. Pathology oftumors of the nervous
system, 4th ed. Baltimore: Williams and Wilkins, 1977.
2. Nugent IL, Bunn PA Jr, Matthews M], et al. CNS metastases in

CHAPTER 9
Hydrocephalus
Albert B. Butler and David G. McLone
Incidence, 165
Pathophysiology, 165
Etiology and Pathology, 167
Congenital Obstructive Hydrocephalus, 167
Acquired Obstructive Hydrocephalus, 169
Communicating Hydrocephalus, 169
Symptoms, 169
Signs, 170
Hydrocephalus is a pathologic condition in which there
is an increase in the volume of cerebrospinal ﬂuid (CSF)
within enlarged intracranial CSF spaces, most frequently
the cerebral ventricles. Hydrocephalus is not a disease
per se, but the result of one of a heterogenous group of
congenital and acquired pathologic lesions that impede
the normal ﬂow of CSF through intracranial ﬂuid path-
ways. Obstruction to CSF ﬂow results in an imbalance
between CSF production and absorption, and a net ac-
cumulation of CSF within intracranial ﬂuid—containing
spaces. The increase in CSF volume, usually within the
ventricles, may develop slowly or rapidly; the magnitude
of ventricular dilatation and level of elevated CSF pres-
sure will usually depend on where obstruction occurs,
how rapidly obstruction develops, and how complete the
obstruction to ﬂow. Progressive enlargement of the cere-
bral ventricles associated with an impediment to CSF
outﬂow must be carefully distinguished from hydroceph-
alus ex vacua, where CSF volume passively expands to
fill spaces within the CSF system resulting from loss of
cerebral substance.
INCII)ENCE
Although it is not possible to determine the true inci-
dence of hydrocephalus in either the pediatric or adult
A. B. Butler: Division of Neurological Surgery, Northwest-
ern University Medical School, Chicago, Illinois 60611-2906.
D. O. McLone: Section of Pediatric Neurosurgery, Chil-
dren‘s Memorial Hospital, Chicago, Illinois 60614.
165
Princi les 0fNeur0surgery,
edite by Robert G. Grossinan. Rosenber © 1991."
Published by Raven Press, Ltd., New Yor .
Natural History, 170
Diagnostic Studies, 171
Treatment, 173
Selection, 173
Indications, 173
Shunt Procedures, 173
Outcome. 176
References, 176
population, the occurrence of hydrocephalus in the in-
fant and older child can be obtained from several reviews
of this subject (1-7). These studies and reviews indicate
that, in general, the incidence of hydrocephalus, alone or
in combination with spina bifida and myelodysplasia,
ranges from less than 1 to 4 per 1,000 live births. The
highest incidence has been reported in Ireland, where
Coffey and Jessop found hydrocephalus occurring in 3 to
4 of every 1,000 births (1). Hydrocephalus has been
shown to occur in 0.5 to 1.0 per 1,000 births in several
studies of hydrocephalus in the United States. Hydro-
cephalus associated with spina bifida and myelodyspla-
sia was detected in 0.4 to 0.9 per 1,000 births. Thus, the
combined incidence of hydrocephalus has been shown
to approximate 1.1 to 1.7 cases per 1,000 births in this
country.
Further study of the incidence of hydrocephalus, espe-
cially in the pediatric age group, can be expected to dem-
onstrate a greater incidence, especially in the category of
hydrocephalus unassociated with spina bifida and mye-
lodysplasia. An increased appreciation of hydrocephalus
associated with intraventricular hemorrhage in the peri-
natal infant and documentation of its presence with com-
puterized tomography (CT) scanning will surely lead to
the detection of a higher incidence of hydrocephalus.
PATHOPHYSIOLOGY
Pathoanatomical and pathophysiological aspects of hy-
drocephalus are best understood when compared to the

166 / CHAPTER 9
normal anatomy and physiology of the CSF system.
Only a brief review of some basic aspects of the normal
system is presented here.
Most cerebrospinal ﬂuid is produced within the cere-
bral ventricles, by both the choroid plexus (70 percent)
and brain parenchyma (30 percent) (8). The rate of CSF
production, approximately 0.35 cc per minute or about
500 cc per day, is quite consistent throughout both the
normal pediatric and adult population (9-10). Resting
CSF pressure, however, may range from 40 to 50 111111
H2O in the infant (11), and 100 to 150 nrnr H2O in older
children and adults (8,12). Once formed within the ven-
tricular system, CSF passes through the paired lateral
and single medial apertures of the fourth ventricle into
the subaraclmoid space (SAS). From this distribution
point, ﬂuid moves either caudally into the spinal sub-
arachnoid space or anteriorly through cisterns located
anterior and posterior to the brainstem and in communi-
cation with the subaraclmoid space at the base of the
brain. From the basal subarachnoid spaces, CSF ﬂows
through the subaraclmoid space surrounding the cere-
bral hemispheres to the arachnoid villi. The arachnoid
villi, located in the wall of the major dural venous si-
nuses, are generally considered to be the major site for
CSF absorption, although other pathways for absorp-
tion, while not clearly documented in humans, have
been demonstrated in experimental animal studies. This
evidence suggests that CSF may drain into the cervical
lymphatics (13), presumably through extensions of the
subarachnoid space around olfactory nerves. CSF may
also leave the subaraclmoid space around spinal nerve
roots, as arachnoid villi protruding into peridural veins
at the root exit zone have been demonstrated on histo-
logic examination in both animal and human studies
(14). The precise role of these alternate or additional out-
ﬂow pathways in the normal, and particularly in the ob-
structed, CSF system has not yet been clearly defined.
The system of freely communicating spinal and intra-
cranial CSF spaces may be viewed as a moderately dis-
tensible series of ﬂuid compartments enclosed within the
skull and vertebral column. In this system, CSF pressure
is normally maintained within a relatively narrow range.
Transient alterations in volume are compensated for by
regulatory mechanisms that determine the rate of CSF
formation, storage, and absorption. Any expansion of
ﬂuid volume within the normal system is compensated
for by these interacting mechanisms, which include corn-
pliance (defined in terms of volume change per unit
change in CSF pressure and related to the elastic proper-
ties of the craniospinal meninges and blood vessels) and
outﬂow resistance, which modulates CSF volume by
venting ﬂuid through CSF outﬂow sites into the venous
circulation ( 1 5 ). Under conditions of sustained elevation
of CSF pressure, changes in pressure—sensitive outﬂow
resistance to ﬂuid absorption protect against large in-
creases in volume, whereas changes in compliance deter-
mine the initial transient response to volume expansion.
The functional role ofthe CSF system in spatial compen-
sation is thus determined by how readily ﬂuid is trans-
ferred frorn one compartment to another or, more irn—
portantly, how rapidly it leaves the CSF system. The
effectiveness of this mechanism requires an unin-
terrupted ﬂow of CSF throughout the system and nor-
mal function of the outﬂow pathways that determine the
resistance to passage of CSF into the venous blood. In
the normal CSF system outﬂow, resistance is generally
considered to be established by the anatomic and func-
tional state of arachnoid villi. It is also reasonable to
assume that some part of total outﬂow resistance is de-
termined by the patency of the pathways extending from
the loci of CSF production to where it is absorbed.
These considerations assume greater importance in
the pathologically altered CSF system, where, in most
instances, the basic abnormality, regardless of the patho-
logic abnormality, is that of increased resistance to out-
ﬂow associated with little or no reduction in CSF produc-
tion (10,15). Thus, as ﬂuid absorption represents the
primary compensatory mechanism for pressure homeo-
stasis under steady—state pressure conditions, any patho-
logic obstruction of the outﬂow sites or pathways leading
to the outﬂow sites invariably leads to an increased resis-
tance to outﬂow. This results in an inability to absorb a
quantity of CSF equivalent to that produced, a condition
necessary to the maintenance of volume and thus pres-
sure homeostasis. The resulting accumulation of CSF
eventually leads to dilatation of the CSF spaces.
When considering the pathophysiology oﬂ1ydrocepha—
lus, it is helpful to review some aspects of the classiﬁca-
tion of hydrocephalus as they relate to the location of the
obstructing lesion and the various syndromes frequently
encountered. Currently, hydrocephalus is by convention
described as either obstructive (noncommunicating), or
nonobstructive (communicating). Obstructive hydro-
cephalus signiﬁes a complete or incomplete obstruction
to CSF outﬂow within or at the exit sites of the ventricu-
lar system. Communicating hydrocephalus is diagnosed
when complete or incomplete obstruction to ﬂow is lo-
cated anywhere within the CSF pathways between the
outlets of the fourth ventricle and the sites of CSF ab-
sorption. Further, hydrocephalus may be considered to
be either active (progressive), when ventricular enlarge-
ment is continuous and associated with increased intra-
cranial pressure (ICP), or arrested (chronic), when either
spontaneously or by inserting a shunt, there is a lack of
further dilatation of the ventricles and a normalization
of intracranial pressure.
Although by this definition a state of spontaneous
arrest of hydrocephalus implies resolution of the patho-
logic process and no further cause for brain dysfunction,
this is often not the end result. For example, the syn-
drome of normal—pressure hydrocephalus, in which pro-
gressive dementia, gait disturbances, and urinary inconti-
nence are diagnosed in a patient exhibiting normal CSF
pressure and dilatation of the ventricles, emphasizes that

chrorric or arrested hydrocephalus cannot be assumed to
be "cured" without a clear definition of the dynamic
aspects of the CSF circulation in these patients.
Acute, obstructive hydrocephalus (16) is a condition
in which sudden obstruction to ﬂow within or outside of
the ventricular system occurs and in which little time is
available for compensatory volume shifts to occur in
order to establish a state of equilibrium. Accordingly, a
rapid deterioration of cerebral function generally occurs,
usually associated with rapidly increasing CSF pressure.
A partial or more gradual obstruction to ﬂow within the
ventricular system, however, may provide time for com-
pensation to occur. Unfortunately, the mechanisms
posed for regulation of an increasing ventricular ﬂuid
volume, particularly in the case of complete obstructive
hydrocephalus, are not yet clearly understood. Tra1rs—
eperrdymal migration of CSF into the periventricular
white matter has been demonstrated in experimental an-
imal studies of hydrocephalus, by CT, and by magnetic
resonance imaging (MRI) of the hydrocephalic patient
where periventricular lucency is interpreted as represe1rt—
ing accumulation of CSF within the periventricular tis-
sues. It has been proposed that absorption of CSF by
vessels within the periventricular white matter may be
one mechanism for decompression of the increasing vol-
ume of intraventricular ﬂuid (17). There is no unequivo-
cal evidence at the present tinre, however, that ﬂuid is in
fact absorbed within the periventricular zone or that
there is migration of the ﬂuid across brain into the sub-
araclmoid space under these conditions.
Some investigators have proposed that the increased
ﬂuid pressure associated with irrtraverrtricular obstruc-
tion carr act to reduce CSF production. Most evidence
now indicates that CSF production is not signiﬁcantly
inﬂuenced by irrtracranial hypertension until cerebral
perfusion pressure drops to less than 50 mm Hg, a co1rdi—
tion not usually seen in either experimental obstructive
hydrocephalus simulating that occurring in humans, or
in the human patient. Obstruction of the outlet sites of
the fourth ventricle may be compensated for by cornmu—
nication of the fourth ventricle with the central canal of
the spinal cord, in which case ﬂuid exits through the
caudal opening of the central canal. Fluid absorption
then presumably occurs either within the spinal sub-
araclmoid space or at the usual sites within the i1rtracra—
nial compartment, if communication persists between
the crarriospirral subaraclmoid spaces.
Hydrocephalus resulting from the narrowing or ob-
struction of the subaraclmoid space at the base of the
brain or over the corrvexities proximal to or at the arach-
noid villi generally progresses rnore slowly. Sudden, pre-
sumably complete, obstructiorr to ﬂow through the sub-
arachnoid pathways does occur, however, as may be seen
after massive subarachnoid hemorrhage, which can lead
to significant hydrocephalus and raised irrtracrarrial
pressure within a short period of time. Here also, effec-
tive compensation for ﬂuid accumulation and mass ef-
HYDROCEPHALUS 167
fect, and thus for ventricular size, is dictated by both the
site and the rapidity of obstruction. A slowly progressive
and incomplete obstruction of the subarachnoid space
may eventually lead to significant dilatation of the vea-
tricles. However, by progressing insidiously over a long
period of time, signiﬁcant ventricular enlargement is not
necessarily associated with elevations of ICP or compres-
sion of brain substance sufficient to cause overt signs or
symptoms.
ETIOLOGY AND PATHOLOGY
In the past hydrocephalus has been classiﬁed as both
internal and external. lrrterrral hydrocephalus is defined
as ventricular enlargement associated with any type of
irrtraverrtricular obstructive pathology; external hydro-
cephalus is diagnosed when only enlargement of the SAS
is identified. Although these ternrs are no longer in corn-
mon use, interest has again been directed to the possibil-
ity that external hydrocephalus may irr fact occur alone
in some instances. This diagnosis has recently been corr-
sidered irr sonre infants and children exhibiting 1nacro—
cephaly (19-23). The demonstration of an enlarged
subarachnoid space over the cerebral hemispheres by
computerized scan in some macrocephalic children may
represent an early form of communicating hydrocepha-
lus. In this condition, it has been proposed that there is
obstruction to CSF ﬂow in the distal subarachnoid space
or at the arachnoid villi, which may in many instances
represent the end result ofperirratal irrtraverrtricular hem-
orrhage or meningitis. It has also been suggested that, in
the resulting state of progressive net accumulation of
CSF, there is an initial dilatation of the SAS proximal to
the obstruction, which, if this process continues without
equilibration, causes further ﬂuid accurrrulation proxi-
mally in the SAS as limited by brain elasticity. Subse-
quently, with continuing accunrulation of ﬂuid the ven-
tricles then dilate, leading to identifiable hydrocephalus.
The list of pathologic alterations of the central nervous
system causing hydrocephalus contains a heterogenous
group of both congenital and acquired lesions. The
various abnormalities are almost exclusively associated
with obstructions to CSF outﬂow within either the ven-
tricles or the intracranial subarachnoid spaces. Russell's
comprehensive review (24) of the pathologic anatomy of
hydrocephalus indicated that well in excess of 90 percent
of the cases detailed in this classic study exhibited me-
chanical obstruction of the CSF pathways associated
with impaired circulation of the CSF.
Congenital Obstructive Hydrocephalus
Of those patients harboring congenital lesions causing
obstruction of CSF ﬂow within or at the outlets of the
ventricular system, two—thirds are found to have aque-
ductal ste1rosis—a narrowing or occlusion of the aque-

l68 / CHAPTER 9
duct of Sylvius. Four types of aqueductal stenosis have
been described (5,24): aqueductal gliosis, forking, true
narrowing, and obstruction of the aqueduct by a thin
neuroglial membrane or septum. Gliosis and forking of
the aqueduct are the two most common causes of aque-
ductal obstruction. Aqueductal gliosis, most often
caused by proliferation of subependymal fibrillary astro-
cytes, results in narrowing or complete occlusion of the
aqueduct. Although this form of aqueductal stenosis is
considered to be congenital, it is also possible that gliotic
obstruction of the aqueduct may represent the end result
of an acquired pre— or postnatal infection. Experimental
induction of aqueductal stenosis by fetal infection with
virus has shown that necrosis of ependymal cells lining
the aqueduct occurs, leading to stenosis without evi-
dence of residual inflammatory changes (25). Likewise,
the presence of blood within the ventricles of preterm
infants with perinatal intracranial hemorrhage could
lead to reactive changes in the aqueductal ependyma,
and subsequent narrowing and occlusion.
Forking of the aqueduct is characterized by the pres-
ence of several channels, separated by normal irrterven—
ing neuropil, that communicate or end blindly. There is
a high incidence of aqueductal forking in association
with other developmental anomalies, including Arnold-
Chiari malformation, spina biﬁda, and myelomeningo—
cele. This association suggests that the etiology of this
anomaly may be related to a true maldevelopment of the
aqueduct rather than its being inflammatory in origin.
True narrowing of the aqueduct is rare but, when found,
is characterized by a significantly smaller than normal
aqueduct that is histologically normal. The presence of a
thin ependymoglial membrane or septum occluding the
caudal end of the aqueduct is likewise rare and is proba-
bly the result of chronic inﬂammation of the ependyma
and glia.
Among the most common congenital anomalies asso-
ciated with hydrocephalus in early life is the Chiari II
malformation (Fig. 1). This malformation appears to re-
sult frorn the leakage of cerebrospinal ﬂuid from the
neural tube defect. This leads to collapse of the ernbry—
onic ventricular system and the induction of the mesen—
chyme to form a small posterior fossa. With the develop-
ment of the small osseous posterior fossa and the normal
development of cerebellar and brainstem tissues, there is
both upward and downward herniation of these struc-
tures. This leads to compression of the hindbrain ele-
ments and obstruction of the cerebrospinal ﬂuid path-
ways. The beaking of the quadrigeminal plate and
superior cerebellum extend upward above the dysplastic
tentoriurn. The vermis and brainstem herniate down-
ward into the upper cervical canal. Associated with this,
and thought to be secondary to the lack of distention of
the embryonic ventricular system, are multiple cerebral
anomalies. These include micropolygyria, ectopic gray
matter, and dysgenesis of the corpus callosum. The over-
FIG. 1 . Midsagittal plane MRI scan of achild with myelomen-
ingocoele, demonstrating a typical Chiari ll malformation.
Changes include a large massa intermedia, beaking of the
quadrigeminal plate, flattening and elongation of the fourth
ventricle, and kinking of the brainstem at C-2.
lying membranous bone development is also abnormal,
secondary to the lack of the distention of the ventricular
system, and this leads to the leukenschadel deformity of
the skull. It has been reported that most patients with a
Chiari II malformation have obstruction at the aque-
duct. Our experience, however, suggests that this ob-
struction is rnore often at the outlets of the fourth ventri-
cle and in the region of the dysplastic terrtoriurn.
Congenital lesions that cause obstruction of the ine-
dial or lateral apertures of the fourth ventricle are seen
most frequently as atresia of these foramina, causing cys-
tic dilatation of the fourth ventricle (Da1rdy—Walker
cyst). This pathologic condition, in which the patient
usually presents with hydrocephalus early in life, is char-
acterized by an enlarged posterior fossa associated with a
large fourth ventricle, absent inferior vermis, and up-
ward displacement of the torcular, falx, and lateral si-
nuses (Fig. 2). The malformation is also frequently asso-
ciated with other systemic and cerebral malformations,
including agenesis of the corpus callosum and heteroto—
pias.
In addition to these more common congenital lesions,
space—occupying lesions may directly obstruct or, by dis-
placement of normal brain structures, impede CSF out-
ﬂow. Congenital cysts, classified as arachnoid or ependy-
mal, are often found within the subaraclmoid spaces
over the hemispheres, at the base of the brain, and in the
posterior fossa. Cysts in the latter position are to be distin-

guished from Dandy—Walker cysts. A congenital cyst,
frequently ependymal in origin, may also be located
within a ventricle and cause loculation of a single ventri-
cle or of the entire ventricular system, depending on its
position. Porencephalic cysts, when of sufficient size and
not in communication with the ventricles, may also ob-
stiuct CSF outﬂow. Congenital tumors in early life, fre-
quently in a midline position, may first present with
hydrocephalus and include craniopharyngiomas, epen—
dymomas, inedulloblastoinas, and teratomas. Similarly,
vascular malformations of developmental origin may
also impede or obstruct CSF outﬂow. Aneurysmal dila-
tation of the vein of Galen or, less frequently, an arterial
aneurysm or larger vascular malformation may also ob-
struct CSF ﬂow by displacement of the brain.
Acquired Obstructive Hydrocephalus
Acquired lesions that cause obstructive hydrocephalus
are somewhat less diverse in origin and, as a general iule,
more likely to be found in all age groups than are congen-
ital lesions causing obstructive hydrocephalus. Intra-
and paraventricular tumors are the most common ac-
quired obstructive lesions and include choroid plexus
papillomas, ependymomas, colloid cysts, ectopic pineal-
oinas, and meningiomas. Paraventricular tumors, either
intra— or extraaxial, may invade the ventricle and cause
obstiuction, as in the case of subependymal astrocyto—
inas causing aqueductal stenosis. They may also, by
growing within or outside of the brain, cause brain dis-
placement, distortion of the ventricle, and occlusion of
the foramen of Monro or aqueduct of Sylvius. In addi-
tion to a wide variety of malignant and benign intra— and
extraaxial tumors of both the supratentorial compa1t—
HYDROCEPHALUS / 169
FIG. 2. Midsagittal plane MRI scan of a child
with Dandy—Wa|ker malformation, demonstrat-
ing a large cyst occupying the posterior fossa
and elevation of the torcular. A small remnant
of the superior cerebellar vermis is com-
pressed on the quadrigeminal plate. This child
also has a small encephalocoele protruding
from the cyst, an abnormality occasionally
seen with this malformation.
ment and the posterior fossa, nontumorous masses, in-
cluding abscesses, intra— and extraparenchymal hemato-
inas, giant aneurysms. and granulomas may cause
ventricular distortion and obstruction. less frequently
encountered, but worthy of consideration among those
acquired lesions causing obstructive hydrocephalus, are
inﬂammatory conditions of the ventricular ependymal
lining, which result in ependymoglial scairing. Inﬂa1n—
matory ependymitis, secondary to intraventricular bacte-
rial and viral infections or hemoirhage into the ventricle,
often leads to narrowing or obstruction of the ventricles,
particularly in the regions of the foramen of Monro, aq-
ueduct of Sylvius, and the fourth ventricle apertures. Bac-
terial infections, either primary or secondary to surgical
procedures such as shunt insertion, are especially likely
to cause this condition.
Communicating Hydrocephalus
Congenital lesions causing communicating hydro-
cephalus are few and generally include lesions where in-
ﬂammation of the meninges has occurred. Although lep-
tomeningeal inﬂammation may be presumed to have
occurred prenatally, in many instances the cause is hem-
onhage or infection in the perinatal period.
SYMPTOMS
Clinical features of the hydrocephalic patient will of-
ten differ among various age groups. Across all age
groups, however, the symptoms associated with hydro-
cephalus are most often those of intracranial hyperten-
sion. Symptoms of increased intracranial pressure are
not as easily recognized in the infant as in the older child

170 / CHAPTER9
or adult and may be seen as drowsiness, irritability, vorn—
itirrg, reduced activity, and failure to thrive. In the older
child, ventricular enlargement and raised intracranial
pressure are easily recognized when there is rapid progres-
sion of hydrocephalus associated with bifrorrtal or dif-
fuse headache, nausea, vornitirrg, and lethargy. When
hydrocephalus develops more slowly, symptoms of cere-
bral dysfunction may initially exist as the only indication
of hydrocephalus, although symptoms of severe i1rtracra—
nial hypertension may develop in later stages of the dis-
ease. Here, the history obtained from the patient and
family may suggest changes in personality, behavioral
difficulties, dullness of affect, and. during the school
years, changes in scholastic performance. These, and
symptoms of intermittent mild headache, may go unrec-
ognized unless the diagnosis is considered at this stage
and investigated. Symptoms of hydrocephalus in the
adult may also va1r.'. In general, symptoms are those re-
lated to either elevated—pressure or 1rormal—pressure lry—
drocephalus. In the former, rapid onset of headache, stu-
por, nausea, arrd vomiting occur in acute obstructive
hydrocephalus. In contrast, in those patients in whom
obstruction of CSF flow develops more slowly and in
whom ventricular size and ICP increase slowly as well,
symptoms of intermittent and often vague headache,
slow mentation, confusion, and changes in behavior and
personality are more likely to occur. In most instances,
unrecognized, gradual progression of the pathologic
state eventually leads to a stage where overt symptoms of
increased ICP are readily apparent.
Normal—pressure, or occult, hydrocephalus (NPH) is
characterized by the presence of symptoms of diffuse
brain dysfunction without intracranial hypertension
(26-28). Deterioration of mental function, manifest ini-
tially as impairment of memory, insidiously progresses
to confusion and more obvious deterioration of mtellec—
tual function associated with disturbance of gait and
bladder control.
SIGNS
Signs associated with hydrocephalus, as with syrnp—
tomatic presentations, vary according to the patient's
age group. The hydrocephalic infant usually presents
with a head circumference greater than that expected for
the infant's age or is shown by serial measurements to
exhibit a rate of head expansion exceeding the usual per-
centile norms for his or her age. The anterior fontanel is
usually large and may be bulging. This is often associated
with dilated scalp veins. Many children will show the
"setting su1r" sign, which is thought to be the result of
compression of the quadrigeminal plate. The "setting
su1r" phenomenon is usually reversible within a short
time after insertion of the shunt system. However, on
occasion, it persists in spite of adequate shunting of the
cerebrospinal fluid. In advanced infantile lrydrocepha—
lus, disproportionate growth of the skull relative to the
face, frontal bossing, convexity of the temporal fossae,
widening of the sutures, and a globular or rounded shape
of the skull are commonly seen.
In childhood, especially after closure of the sutures,
signs indicating the presence of hydrocephalus are less
frequently those of head enlargement and more often
those of rreurologic dysfunction as the ventricles expand.
Neurologic dysfunction may also be caused by the lesion
responsible for obstruction of CSF flow. Altered motor
function and gait, presenting as spastic paraparesis or
quadriparesis, limb tremor, or ataxia are often detected.
Papilledema and, less frequently, optic atrophy may be
detected, as well as altered visual acuity, hemianopsia, or
constricted visual fields. Cranial nerve examination may
reveal sixth nerve paresis and paralysis of upward gaze.
The major signs of progressive hydrocephalus in the
adult are those of altered cerebral function, secondary to
intracranial hypertension and to involvement of brain
and cranial nerves by the pathologic lesion causing ob-
struction of CSF ﬂow. Sudden or rapidly progressive ob-
struction of CSF pathways quickly leads to acute lrydro—
cephalus and signs of altered level of consciousness,
papilledema, vomiting, and cranial nerve and cerebral
dysfunction related to the obstructive lesion. Where
narrowing or obstruction of CSF pathways develops
more slowly, usually within the basal or convexity sub-
arachnoid space, gradual onset of signs is more likely to
occur. In the hydrocephalic child with closed sutures,
mild papilledema, gait apraxia, and paresis of limbs and
of the muscles supplied by the sixth cranial nerve may
often precede the stage where overt signs of intracranial
hypertension and cerebral dysfunction occur. In corr-
trast, rniddle—aged or older hydrocephalic patients with
1rormal—pressure, or occult, hydrocephalus (NPH) may
present with signs of motor dysfunction, especially of the
lower limbs. This motor deficit may range from a very
mild gait apraxia, in which tandem walking is difficult to
perform and the gait tends to be broad—based and u1r—
steady, to a state of severe impairment of lower extrern—
ity function with considerable difficulty in initiating
movement as a result of spastic paraparesis. In the later
stages of this disease, urinary incontinence often de-
velops as well. Signs of mental deterioration are the third
of the triad of signs diagnostic of NPH and are clraracter—
ized by progressive slowing of spontaneity and initiative
leading to apathy, decrease in attention span,"nd, eve1r—
tually, profound psychomotor retardation and occasio1r—
ally akinetic rnutisrn (26,28).
NATURAL HIS TORY
The natural history of hydrocephalus has been de-
scribed irr most detail in studies of untreated infants and

children with hydrocephalus, most notable of which are
the series reported by Hagberg and by Laurence (29-31).
In both series, large groups ofhydrocephalic infants were
followed from infancy into childhood. Approximately
half of the children died, many within the first 18
months of life. Of those surviving, detailed assessment of
intellectual function showed the average IQ of the
arrested patients to be 69. In 41 percent, the IQ was over
85; in 29 percent, less than 50. Among those surviving,
deterioration of neurologic function was also frequently
observed, in many instances significantly disabling. Neu-
rologic sequelae of varying severity noted most fre-
quently included ataxia, spastic paraparesis, cranial
nerve disorders, deteriorating vision, and slow develop-
ment. Laurence noted that a highly significant correla-
tion exists between IQ and physical disability, in which
the physically disabled showed the most significant rnen—
tal handicap (31). Of those children who were shown to
have normal intelligence, or at least were educable, ap-
proximately half demonstrated a neurologic deficit,
which in many was disabling. The results of these follow-
up studies indicate that the more severe the hydrocepha-
lus, the greater the tendency to develop severe disability
and mental retardation. Hagberg estimated that there is
only a 15 percent chance of a child surviving infantile
hydrocephalus with an IQ of 90 or higher and only a 5
percent chance of surviving with normal intelligence,
neurologic function, and behavior. Laurence and Coates
determined that only 20 percent of the survivors in their
series were likely to reach adulthood (30).
DIAGNOSTIC STUDIES
Radiographic studies now available for examining the
hydrocephalic patient provide the clinician with a van-
ety of methods to more precisely identify and localize the
lesion obstructing CSF flow, to accurately determine
changes in the CSF spaces over time, and to assess patho-
,dynamic alterations of CSF ﬂow within various corn-
partments of the CSF system (32). Only those diagnostic
studies appropriate for examining the more common
forms of hydrocephalus will be discussed here.
The wide availability of CT and MRI scanning and the
significant advantages that these scanning methods offer
in the diagnosis and assessment of hydrocephalus have
led to the infrequent use of skull x—rays in diagnosing
patients suspected of having hydrocephalus. Nonethe-
less, useful information may be obtained from a thor-
ough examination of skull x—rays. Most frequently seen
are an increase in the size of the skull relative to the face,
sutural separation, thinning of the calvarial bone, ﬂat-
tening of the skull base, and atrophy of the supraorbital
ridges. In older children with hydrocephalus and intra-
cranial hypertension, digital impressions are often evi-
dent. Asymmetry of skull development in the infant may
HYDROCEPHALUS / l7l
provide some indication of the speciﬁc type of hydro-
cephalus. Appreciation of these deformities, which often
persist through childhood and into adult life, may aid in
establishing the diagnosis. Unilateral enlargement of the
lateral ventricle will often cause asymmetric expansion
of the skull on the side of the large ventricle. Dispropor—
tionate enlargement of the supratentorial skull relative
to that occurring below the tentoriuin may suggest the
presence of aqueductal stenosis, whereas the reverse con-
dition is seen with posterior fossa cysts or localized ob-
struction of the fourth ventricle. Communicating hydro-
cephalus tends to cause symmetric but greater than
normal expansion of the skull, resulting from an increase
in the size of all of the ventricles. Skull x—rays may also
show craniolacunae, a condition of rarefaction of the
skull, often associated with hydrocephalus and meningo—
rnyelocele. Calcifications are frequently seen in infec-
tions such as cytoinegalic inclusion disease and toxo—
plasinosis. conditions occasionally associated with
hydrocephalus. The location and type of calcifications
may suggest a speciﬁc intracranial lesion, such as a cra-
niopharyngioma. pinealoma, or choroid plexus papil-
loina, which may be in a position to cause hydrocepha-
lus by obstruction of CSF pathways. In older children
and adults, radiographic signs on plain x—rays that sug-
gest hydrocephalus and elevated intracranial pressure in-
clude erosion of the dorsurn sellae and posterior clinoids,
and abnormal convolutional (digital) markings.
Computed tomography (CT), magnetic resonance
imaging (MRI), and cranial ultrasound are now the most
widely used diagnostic studies for initial evaluation of
the patient with suspected hydrocephalus. These scan-
ning methods have virtually eliminated the need for in-
vasive procedures such as pneumoencephalography and
ventriculography. For all age groups, the CT or MRI
scan permits the clinician to define the extent of ventricu-
lar enlargement and frequently provides an accurate
diagnosis of the obstructing lesion and a precise means
for determining the effectiveness of a shunting proce-
dure and for diagnosing such complications as subdural
collections of ﬂuid or blood. The decision to use CT ver-
sus MRI scanning to diagnose and evaluate hydrocepha-
lus requires consideration of a number of factors. CT
scanning offers the advantages of wide availability, ease
of use, less cost, and shorter scanning times. Both CT
and MRI clearly demonstrate enlargement of the ventri-
cles and widening ofthe subarachnoid space. The advan-
tages of MRI scanning include the ability to diagnose
smaller lesions within the ventricles, to determine the
presence or absence of a ﬂow void in the aqueduct of
Sylvius, to visualize ectopias in the patient with a Chiaii
II malformation, and to aid in the diagnosis of some
degenerative processes. While the assessment of change
in ventricular size is best shown with serial CT or MRI
scans, the use of contrast agents, instilled into the sub-
arachnoid space prior to scanning, can at times be of

172 / CHAPTER 9
help in establishing the diagnosis of NPH and in differ-
entiating between communicating and noncommuni-
cating hydrocephalus. Similarly, evaluation of the
shunted hydrocephalic may be improved using these
techniques (also see below). An asymmetric decrease in
the size of the ventricle in which a shunt catheter has
been placed may suggest occlusion of the interyentricu—
lar foramen and an intact septum pellucidum. The intro-
duction of contrast agents such as inetrizainide through
the shunt catheter may provide direct evidence of the
presence or absence of communication between the ven-
tricles.
The availability of portable cranial ultrasound has
greatly improved our ability to diagnose and manage hy-
drocephalus. Prior to the widespread use of ultrasound,
either contrast ventriculography or serial CT scans were
required to monitor changes in the ventricular volume.
With portable ultrasound, progression in ventricular size
can now be monitored on a daily basis at an infant's
bedside. In the operating room, ultrasound is helpful in
establishing the proper placement of the proximal end of
the ventricular catheter. In the postoperative period, it
enables the surgeon to easily monitor the decrease in
ventricular volume and to assess the adequacy of shunt-
ing at follow—up visits. It has become standard practice to
monitor the effectiveness of shunting in children using
ultrasonography. As long as the anterior fontanel re-
mains open, there is access for optimal visualization of
the ventricular system. Our standard practice at this time
is to obtain a baseline CT scan and then follow the child
with serial ultrasound examinations until approximately
1 to l{ years of age, at which time images can no longer
be obtained through the anterior fontanel.
The use of ultrasound and CT has demonstrated a
heretofore difficult—to—understand developmental se-
quence in children. For many years, a group of children
whose head circumference increased at a greater rate
than the normal curve would predict were followed (19-
23). Many of these children were thought to have either a
hygroma or external hydrocephalus. Some had shunts
placed in the dilated extracerebral space, while others
had ventricular shunts placed. With increased use of CT
and ultrasound, however, it is now well established that
there is a group of children who appear ultimately to be
normal but who go through this period of rapid progres-
sion in head circumference. Many of these children will
extend several standard deviations beyond the 95th per-
centile. The typical child has a globular head and a large
anterior fontanel, but with little sign of increased CSF
pressure. The CT scan will show a large subarachnoid
space located over both frontal poles. The ventricular
system in these children is normal to minimally dilated.
Monthly, serial ultrasound examinations and weekly
plotting of the head circumference often show continued
head growth for two to three months, stable ventricular
volume, and a stable amount of extracerebral ﬂuid. At
about the third or fourth month, the head circumference
stabilizes and often will return toward the normal 95th
percentile. At about one year, 96 percent of these chil-
dren have reestablished a normal subarachnoid space
over the frontal poles and their ventricular volume has
remained normal throughout. Four percent of these chil-
dren will develop either subdural ﬂuid collections or pro-
gressive hydrocephalus. Soine in this latter group will
show signs of developmental delay. Surgical intervention
is indicated in this small group of patients. Although
radioactive agents have been injected into the lumbar
subarachnoid fluid pathways in an attempt to predict
which of this small group of patients will develop a sub-
dural hygroma or hydrocephalus, this diagnostic proce-
dure has been of little value. The best management of
these children is to obtain a baseline CT scan which docu-
ments that the ventricular system is within normal limits
and that the enlarged subarachnoid space is restricted to
the frontal poles. The child should then be followed on a
monthly basis with ultrasonography, until there is resolu—"
tion of this process or obvious progression.
Angiographic examination of the hydrocephalic pa-
tient (33) is used more often in the adult population to
diagnose intracranial mass lesions causing ventricular
obstruction. Although in all age groups CT and MRI
scanning is much more reliable in demonstrating the size
of the dilated ventricles as well as the extent and position
of any mass lesion obstructing CSF pathways, arteriogra—
phy remains the most reliable method for diagnosing
vascular tumors and malformations, aneurysms, and ob-
struction of the dural venous sinuses. Angiography is sel-
dom necessary in the pediatric patient with hydrocepha-
lus, especially in those instances where congenital lesions
are suspected or known. The common use of CT and
MRI scanning of patients with hydrocephalus caused by
acquired lesions has also significantly reduced the need
for angiography. Exceptions include those unusual cases
where a tumor or other mass lesion is suspected but inad-
equately defined by CT or MRI, where surgical planning
requires angiographic visualization of blood supply to
tumors obstructing CSF pathways, and where vascular
lesions are suspected from enhanced CT or MRI studies.
Isotope cisternography requires the introduction of ra-
dionuclide tracers into the subarachnoid space, the dis-
tribution of which throughout the CSF system, as visual-
ized on serial scans, can be of value in assessing
abnormal CSF ﬂow patterns in the hydrocephalic pa-
tient (34). Prolonged retention of tracer within the ven-
tricles is helpful in establishing the diagnosis of normal-
pressure hydrocephalus. Isotope cisternography is also of
benefit in demonstrating the extent of obstruction to
CSF flow within the subarachnoid space and the effect of
extraaxial lesions distorting or obstiucting the ventricles
on CSF flow. Isotopes placed within the ventricles may
also aid in diagnosing loculations within the ventricles.
Although of limited use now, the patency of shunt sys-

terns may also be assessed by examining the patterns of
radionuclide ﬂow after the introduction of the agent into
the shunt reservoir or ventricle (35).
TREATMENT
The treatment of hydrocephalus has undergone con-
siderable change within a relatively short period, espe-
cially considering that shunting of the hydrocephalic pa-
tient has been used as a matter of routine only since the
late 1950s. Alternative forms of therapy for hydrocepha-
lus have been advocated, including pharmacologic treat-
ment with agents such as carbonic anhydrase inhibitors
(36) or osmotic agents such as isosorbide (37), and com-
pressive head wrapping (38). Surgical treatment of most
types of hydrocephalus, however, has proven to be the
most effective therapy over the long term. Surgical meth-
ods for the resolution of hydrocephalus most often in-
clude a shunting procedure designed to temporarily or
permanently bypass the lesion causing CSF pathway ob-
struction.
Selection
Proper selection of the best medical and surgical ther-
apy for the different types of hydrocephalus in the infant
or child requires an awareness of the natural history of
acquired or congenital hydrocephalus and consideration
of how other congenital anomalies, paiticularly myelo—
meningocele and Chiari II malformation, inﬂuence out-
come with or without treatment. This information must
then be carefully considered in light of the most current
results of various surgical procedures and long—te1m out-
come in order to select the most appropriate plan for
treatment of the hydrocephalic patient (39-41).
Indications
The decision for surgical intervention in patients with
hydrocephalus is determined by the presence ofintracra—
nial hypertension, degree and type of neurologic dys-
function, degree of ventricular dilatation, specific type of
pathologic lesion, and the location of the mass causing
CSF obstruction. The preferred surgical approach is to
remove the obstructing lesion and restore the CSF sys-
tem to a normal balance between CSF production and
absorption. Because many lesions causing hydrocepha-
lus are not amenable to a direct surgical approach, how-
ever, shunting procedures are used to divert the CSF
around the obstructing lesion. The hydrocephalic child
or adult presenting with a mass lesion in the posterior
fossa is frequently best treated by surgical removal ofthe
mass lesion. In the past, shunting of the supratentorial
ventricles prior to surgical resection of a posterior fossa
HYDROCEPHALUS / 173
tumor or other mass lesion was considered advisable.
However, a large multi—institutional study showed that
the complications of shunting the enlarged supratenior—
ial ventricles often lead to a poor outcome and an unac-
ceptably higher mortality (42). Presently, posterior fossa
tumors are better approached directly without shunting
the supratentorial ventricles. Hydrocephalus resulting
from a posterior fossa lesion resolves following surgical
removal of the mass in most children. Approximately 20
to 25 percent of these children will require a ventriculo—
peritoneal shunt because of persistent hydrocephalus fol-
lowing removal of the posterior fossa lesion. Other con-
ditions in which the pathologic lesion responsible for
hydrocephalus can be treated by direct surgical interven-
tion include arachnoid cysts, craniopharyngioma, and
various intraventricular tumors.
Shunt Procedures
Bypass procedures using either intracranial or extra-
cranial shunts are currently the most common means of
treating hydrocephalus. lntracranial shunting from one
craniospinal fluid compartment to another is no longer
the initial procedure of choice for treatment of the more
common forms of hydrocephalus in both children and
adults. Ventriculocisternostomy. as advocated by Tor-
kildsen (43) and modiﬁed by others, requires placement
of one end of a shunt catheter within the lateral ventricle
and the other in the cisterna magna or the upper cervical
subaraclmoid space. Although the rate of failure is fairly
high, especially when used in the younger age group.
Ventriculocisternostorny can be advantageous in selected
cases, including acquired aqueductal stenosis and where
tumors occlude the third ventricle or aqueduct of Syl-
vius. This procedure has also been used to temporarily
decompress the ventricular system so that reexpansion
of the subarachnoid space can occur (44). Thereafter, a
standard ventriculoperitoneal (VP) or ventriculojugular
(VJ) shunt can, in most instances, be expected to func-
tion rnore effectively. Milhorat has suggested that the
ventriculocisternal shunt can be advantageous in se-
lected cases of noncommunicating hydrocephalus in
which the obstruction to ventricular outﬂow cannot be
directly removed, the sub arachnoid space has been de1n—
onstrated to be open by radiologic investigations, and
the third ventricle is sufficiently obstructed to make
third ventriculostomy impossible (I 6). Another intracra-
nial shunting procedure is third ventriculostomy (45-
47), which is now rnost often performed by puncture of
the lamina terminalis. The initial high rate of failure of
this procedure and access to more reliable VP shunts
have considerably reduced the instances in which punc-
ture of the lamina terminalis is necessary.
Diversion of CSF from the ventricle to an extracere—
bral vessel or body cavity by means of a valved shunt is

174 / CHAPTER9
the most frequently used method of treating hydrocepha-
lus (48-49). The two shunt systems used are those in
which the distal catheter is placed in the right atrium via
the internal jugular vein or into the peritoneal cavity.
Surgical bypass by VP or VJ shunt, particularly the lat-
ter, is associated with a number of potentially serious
complications. The majority of these complications, al-
though infrequently life—threatening, may require hospi-
talization for revision of a malfunctioning shunt or treat-
ment of the infected shunt and, often, Ventriculitis.
Additionally, once shunted, most hydrocephalic patients
will require careful follow—up examination of shunt
function after the initial procedure, as nrost are assumed
to be "shunt dependent." It has been confirmed over
time that, once shunted, the altered CSF system infre-
quently reverts to a state where a satisfactory balance
between CSF production and absorption can be antici-
pated after shunt removal. Nevertheless, considering the
disadvantages and relative ineffectiveness of other fornrs
of therapy, proper selection of the appropriate shunting
procedure and meticulous attention to all surgical details
should provide the nrost effective method available for
decompression of enlarged ventricles.
The indications for placement of a shunt are most
clearly defined in those patients in whom obstructive
hydrocephalus is caused by a congenital or acquired le-
sion causing narrowing of intra— or interventricular ar-
eas, such as an infiltrating tumor occluding the foramen
of Monro or aqueduct of Sylvius, congenital atresia of
the aqueduct, or a posterior fossa tumor. Conversely,
indications for shunting are not as well defined for treat-
ment of occult or normal—pressure hydrocephalus (27).
Although the more recent combined use of CT or MRI
scanning, isotope or metrizamide cisternography, and
neuropsychological testing has nrore clearly defined cer-
tain aspects of the clinical condition, the means by which
to accurately predict if these patients will respond satis-
factorily to shunting are not yet available.
When considering the placement of shunt, absolute
contraindications to shunt insertion include generalized
sepsis and infection confined to the ventricular or sub-
arachnoid CSF. Additionally, other associated condi-
tions, including lrypo— or hypercoagulation states,
previous extensive intra—abdominal operations, extreme
debilitation, thrombosis of the internal jugular vein or
superior vena cava, congenital heart disease, and other
cardiac or pulmonary anomalies, may require the sur-
geon to defer the operation, choose an alternate site for
shunt insertion, or utilize temporizing procedures, such
as external ventricular drainage, lumbar puncture, or in-
tracranial shunting procedures, depending on the partic-
ular circumstances.
At the present time, the VJ shunt has limited use and
is now generally restricted to those individuals who do
not have an adequately functioning peritoneal or pleural
space. Problems with the VJ shunt are largely those of
late complications, including cardiac, pulmonary, and
renal injury. Complications are often insidious and may
result in long—term damage. The VJ shunt when placed
in young children does not allow for growth and thus
requires prophylactic lengthening of the cardiac end of
the shunt. Revision of this system appears to be more
difficult than for the VP shunt, although that may be
simply due to the lack of familiarity or the decreased
frequency with which this shunt systenr is utilized.
Although the techniques for insertion of either the VJ
or VP shunt are not detailed here, some general princi-
ples of the operative procedures are reviewed, as the suc-
cess or failure of the shunt systenr used is frequently the
direct result of the attention or lack of attention given to
the meticulous details ofproper insertion. Accurate posi-
tioning of the ventricular catheter tip is one critical
aspect of the shunting procedure. Careful measurement
of ventricular size and position of the interventricular
foranren and choroid plexus on CT is inrportant when
considering the optimal positioning of the ventricular,
end of the catheter. The best catheter placement, as de-
ternrined by intraoperative x—ray, should leave the tip of
the ventricular catheter within the anterior horn of the
lateral ventricle, anterior to the choroid plexus lying
along the ﬂoor of the ventricle (50). Alternative nrethods
for shunt positioning include placement within the occip-
ital horn, well posterior to the glomus of the choroid
plexus at the ventricular atrium (532); or, preferably,
frontal insertion of the ventricular catheter, where, by
insertion through a burr hole placed near the coronal
suture, the catheter is placed within the frontal horn.
Placement ofthe distal tip of the catheter of a VJ shunt
within the venous system also requires careful assess-
ment of the final position of the catheter. lnitially, after
the catheter is inserted into the facial or internal jugular
vein, filling of the catheter with normal saline for inser-
tion under electrocardiographic (ECG) control or 50
percent hypaque for insertion under x—ray control is ac-
complished. For ECG control, P—wave changes are
watched as the catheter is advanced; a change from the
normal downward to biphasic deﬂection indicates that
the catheter has passed into the atrium (51). A sharp,
upward deﬂection indicates an incorrect position within
the tricuspid valve. Under x—ray control, using a dye-
filled catheter, the catheter tip should be positioned at
the level of the T—6 vertebra, which corresponds to an
acceptable placement within the atrium. More recently,
impregnation of shunt catheters with radiopaque sub-
stances has made the injection of radiopaque dyes into
the catheter for x—ray control unnecessary.
The VP shunt, although technically simpler to place,
necessitates a greater exposure of skin surface for the
operative procedure (48). To prevent infection, there-
fore, considerable attention rnust be given to maintain-
ing asepsis during the initial preparation and draping of
the operative sites as well as throughout the surgical pro-

cedure. The need for revision of the peritoneal end of the
shunt because of retraction of the catheter out of the
peritoneal cavity as a result of linear growth of the infant
and child can be reduced by initial placement of a longer
segment of abdominal catheter.
Complications related to a VJ or VP shunt are most
often due to obstruction or infection. The most frequent
cause for shunt revision of either system is mechanical
obstruction. Within the ventricle, the catheter may be-
come occluded by fluid—borne debris, fronds of choroid
plexus, or collapse of the ventricular walls around the
perforated tip of the catheter in instances in which over-
drainage has occurred. Likewise, the shunt valve may
malfunction as a result of debris, elevated protein, or
hemorrhage in the CSF. Disconnection of the ventricu-
lar catheter from the valve or reservoir may also lead to
shunt malfunction. Distally, retraction of the intraatrial
or peritoneal catheter is a frequent cause of malfunction
unless the younger patient is frequently examined for
changes in catheter position related to linear growth. Re-
traction of the intraatrial catheter tip leads to venous
thrombosis in at least a third of patients in whom the
catheter tip reaches or lies above the level of the T—4
vertebra (50). Likewise, the rate of malfunction of a VP
shunt increases when the distal catheter is retracted out
of the peritoneal cavity. Within the peritoneal cavity,
mechanical obstruction of the catheter may result from
kinking or entrapment of the catheter tip by ﬁbrosis or
omental encasement, resulting in i1rtra—abdominal accu-
mulation of CSF (48).
Shunt infections represent the next most common
complication in both the VJ and VP systems. Coloniza-
tion of the shunt, leading to generalized bacteremia and
sepsis, ventriculitis, meningitis, and occasionally perito-
nitis, is among the rnost serious complications of these
surgical procedures. In addition to creating a predisposi-
tion to shunt malfunction, infection, particularly in asso-
ciation with the VJ shunt, often leads to other serious
sequelae. I1rfection—related thrombus formation around
the atrial catheter can lead to pulmonary emboli and,
eventually, pulmonary hypertension. Shunt nephritis
has also been recognized as a serious complication of the
infected VJ shunt (52-53). Peritoneal infection in the
patient in whom a VP shunt has been placed is less fre-
quently the result of ﬂuid—borne bacteremia; instead, per-
foration of the bowel or other viscus, although u1rcorn—
mon, may cause peritonitis. The patient is at greatest risk
for infection within the first one to two nronths after
shunt insertion. Suspicion of shunt infection is
prompted by a febrile illness associated with leucocytosis
in any patient in whom a shunt has been placed. Head-
ache and signs of meningeal irritation are not always
present unless frank nreningeal infection is diagnosed.
The bacterial organisms most frequently implicated in
shunt infection are Staphylococcus epidermidis and
Staphylococcus aureus. The latter is more commonly as-
HYDROCEPHALUS
sociated with a fulminant sepsis, in which the patient
exhibits obvious signs of acute infection, whereas the
former leads to a more insidious infection, often her-
alded only by low—grade fever, moderate leukocytoss.
and little evidence of acute inflammation systemicallyor
in the ventricular or subarachnoid CSF. These minimal
signs may result in delayed recognition of shunt infec-
tion.
The incidence of shunt infection has been reported to
be as high as 30 to 40 percent (54-59), especially in neo-
nates. More recent studies indicate that acceptable levels
are at 5 percent or below. At the present time, prophylac-
tic antibiotics are used by most centers. However, there
are a number of studies showing that prophylactic antibi-
otics do not alter the incidence of shunt infection. Most
shunt systems utilized today have acquisition ports by
which CSF for culture, cell count, glucose, and protein
may be obtained and analyzed. Thus, suspected shunt
infections may be diagnosed earlier and appropriate ther-
apy begun.
The management of shunt infections has varied. Irri-
tially, attempts were rnade to treat shunt infections with
the shunt system in place. It soon became apparent, how-
ever, that removal of the shunt system, treatment of the
ventriculitis either by systemic or a combination of sys-
temic and intraventricular antibiotics, and then replace-
ment of the shunt system was more effective. We have
found over the years that the best management of shunt
infections has been to completely remove the infected
shunt system and then place the patient on external ven-
tricular drainage. Appropriate intravenous antibiotics
are given for 7 to 10 days and discontinued. If the cul-
tures of the CSF remain negative for 72 hours, the shunt
system is then reinternalized. It is essential that all of the
shunt hardware be removed prior to the treatment of the
ventricular infection as retention of foreign shunt nrate—
rials within the ventricular system makes it almost irn—
possible to totally eradicate the infection (56,60—6l).
Other complications associated with shunt procedures
are numerous and, although each occurs relatively irrfre—
quently, all must be considered when attempting to de-
termine the best way to avoid complications for each
shunt operation. Complications to be considered include
skin breakdown over the subcutaneous valve or tubing,
cystic loculation at the abdominal end of a VP shunt by
omentum, perforation of an abdominal viscus. over-
drainage of the ventricles causing subdural hematoma,
asymmetric or symmetric collapse of the ventricle with
internal shift of brain contents and slit ventricle syn-
drome respectively, conversion ofcommunicating to ob-
structive hydrocephalus (62), postshunt craniosynostosis
secondary to overdrainage and overlap of cranial sutures
(63), progressive thickening of the calvarium, and ab-
dominal ascites as a consequence of poor CSF absorp-
tion by the peritoneum, particularly in young infants
(48). Although not all—inclusive, this list gives some i1rdi—

176 / CHAPTER9
cation of the problems that may be related to altered
physiology secondary to shunting, response to a foreign
body, and failures resulting from inrproper placenrent.
Outcome
The results of shunting for hydrocephalus as indicated
by follow-up studies of shunted children and adults sup-
port its continued use in those categories of hydrocepha-
lus where it is reasonably indicated. In the infantile and
childhood pediatric populations, unselected series show
a survival rate of 70 to 80 percent, with an IQ of 75 or
above expected in at least two thirds of those surviving
(5,32,64-65). Other reviews (57,66-68) suggest the fol-
lowing: the complication rate, when comparing the VP-
shunted to the VJ—shunted patient, varies considerably
but is generally more serious in the VJ -shunted patients.
The revision rate for both shunt systems also differs but,
when considering a number of different series, is roughly
equal. There is a higher infection rate in infants and chil-
dren with hydrocephalus and myelomeningocele, al-
though the long-term outcome for children born with
myelomeningocele and hydrocephalus indicates that the
outlook is much brighter than previously thought. To-
day, the expected suryival rate for children born with
myelomeningocele is between 85 to 90 percent (39-40).
The IQ of 75 percent of these children will be greater
than 80. The selection criteria advocated by Lorber and
others have proven to be invalid; the use of these criteria
does not produce a population of children that is more fit
than simply treating all children without selection.
Fifty percent of children with a shunt inserted at birth
will reach the fifth year without requiring shunt revision
(41). Over the subsequent five years, approximately half
of that group will have had at least one revision. At least
10 to 15 percent of these children will proceed into ado-
lescence without requiring a shunt revision. It is possible
that a small percentage of these children have established
adequate CSF absorption and will never require a shunt
revision.
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CHAPTER 10
Princi [es 0 f \eurraurgary.
edite by Robert G. Gr0ssman-
Published by Harm
Focal Infections of the Central Nervous System,
Skull, and Spine
Perry Black and Michael E. Carey
Brain Abscess, 179
Pyogenic Brain Abscess, 179
Intracranial Tuberculoma, 193
Heipes Simplex Encephalitis (HSE), 195
Parasitic Brain Abscess, 196
Fungal Brain Abscess, 200
Acquired Immunodeficiency Syndrome
(AIDS), 202
Nervous system infections may be caused by bacteria,
viruses, fungi, or parasites that can cause diffuse or local-
ized disease. This chapter deals primarily with focal in-
fections of the nervous system that produce a 1nass of
varying size and that may be amenable to surgical inter-
vention. Because primary attention is directed to those
lesions with neurosurgical implications, diffuse infec-
tions—such as meningitis or encephalitis (other than
herpes simplex encephalitis)—are not considered here.
Despite the availability of antibiotic therapy, focal bac-
terial infections of the central nervous system (CNS)
continue to pose a serious problem with disturbingly
high mortality and morbidity. As outlined in this
chapter, successful management of such infection&,en—
tails the combination of both surgical—deco1npression of
the expanding lesion and carefully selected antibiotic
therapy. This is best achieved by a collaborative effort on
the part of the neurosurgeon and consultants in in-
fectious disease and clinical microbiology, all contribut-
ing the expeitise of their respective disciplines.
P. Black: Department of Neurosurgery, Hahnemann Univer-
sity, Philadelphia, Pennsylvania 19102-1192.
M. E. Carey: Department of Neurosurgery, Louisiana State
University,NewOrleans,Louisiana701 12-2822.
179
Osteomyelitis of the Skull, 204
Spinal Abscess, 204
Pyogenic Infections, 204
Spinal Tuberculosis, 210
Parasitic Spinal Infection, 211
Fungal Spinal Infection, 212
Conclusion, 212
References, 213
BRAIN ABSCESS
Pyogenic Brain Abscess
Hematogenous ("metastatic") brain abscesses occur
when bacteria fro1n elsewhere in the body enter the
blood stream and lodge within the brain. Alternatively,
brain abscesses may arise fro1n direct brain trauma, fro1n
an adjacent inflammation such as osteomyelitis of the
skull, or fro1n sinus/mastoid infection. Occasionally,
brain abscesses are a sequela of meningitis or occur post-
operatively as a complication of craniotomy.
Epidemiology
Cerebral abscess may affect individuals of all ages,
with peaks in the preadolescent, young adult, and 1nid—
dle years (1,2). Males are 1nore frequently involved than
females (3-5). Experience in industrialized countries in-
dicates that an active hospital neurosurgical service may
expect to see fro1n 4 to 10 patients each year with pyo—
genic brain abscess (6-10). The average neurosurgical
practitioner in the United States may see but a single
case each year (11). The situation in developing coun-
tries, however, is quite different. In India, pyogenic brain
abscesses account for approximately 8 to 18 percent of

180 / CHAPTER 10
all intracranial space—occupying masses (12-14), and in
the People's Republic of China, a busy neurosurgical ser-
vice may see up to 20 brain abscesses a year (5).
The spectrum of brain infection varies considerably
worldwide. Parasitic and tuberculous brain infections
are more serious problems than pyogenic abscesses in
many countries. Rodriguez in Mexico City reported that
cysticercosis was responsible for 85 percent of all brain
infections, that tuberculornas accounted for 11 percent,
and that pyogenic abscesses caused 3 percent (15). The
etiology underlying pyogenic brain abscesses also varies,
depending on environmental factors such as trauma (16)
and the widespread existence of sinus/mastoid disease
(8). The availability of neurosurgical care and the pres-
ence of special units handling many patients with con-
genital cardiac abnormalities (17), cystic fibrosis (18), or
immunologic suppression (19) may also alter the under-
lying etiology.
Etiology
Besides cyanotic heart disease with right—to—left car-
diac shunts, pulmonary A—V fistulas may lead to brain
abscesses because blood circulates from pulmonary arter-
ies to pulmonary veins, bypassing the effective bacterial
filtering ability of the pulmonary capillaries (20,21). In
infants and children, cyanotic congenital heart disease is
the most common cause of brain abscess (24 percent of
cases); other major sources of brain abscesses in children
are head trauma, infections of the ear, nose, and throat,
and cases of undetermined origin (22).
Hereditary hemorrhagic telangiectasia (HHT) is a vas-
cular dysplasia in which capillaries and small venules are
deficient in muscle and elastic tissue. Arterial ectasias
and arteriovenous fistulas are also common. More than
200 cases of CNS symptoms associated with HHT have
been reported. Although many of the CNS cornplica—
tions of this disease are consequent to cerebral arteriove-
nous malformations (AVMs), CNS infections ajre hkely
to occur in association with pulmonary AVMs. Patients
with HHT have about 1000 times greater risk of a brain
abscess than the general population (23). Brain < bscesses
have been responsible for about 13 percent of all CNS
complications of HHT (24).
Several reports associate brain abscesses with cystic
ﬁbrosis owing, most likely, to recurring pulmonary in-
fections seen in this disorder (l8,25,26).
Septic infarction may complicate the chnical course of
malignancies, particularly leukemia, carcinoma, and
lymphoma (27). Often patients with systemic rnalignan—
cies are imrnunosuppressed either because of the disease
or in response to treatment. Thus, about 0.5 percent of
those dying of systemic cancer will have significant clini-
cal symptoms referable to septic brain infarcts. Aspergil—
lus and Candida species are the most common causative
organisms.
Acquired immunodeficiency syndrome (AIDS) is as-
sociated with widespread infections, both systemically
and within the CNS. Surprisingly, CNS infections in
AIDS are usually caused by protozoa (e.g., toxoplasrno—
sis) or fungi rather than the common pyogenic organ-
rsrns.
Types ofAbscesses
Traumatic Brain Abscess
These abscesses may rise from open fractures of the
skull, particularly if the dura is torn. Jennett and Miller
found an infection rate of 10.6 percent among 359 such
fractures, usually occurring from inadequate initial
wound care (28). In other series the incidence of ab-
scesses consequent to trauma has varied from1 3 to 28
percent (3—7,10,29). This may depend to some extent on
socioeconomic circumstances of various countries and
neurosurgical referral patterns. Brain abscesses conse-
quent to penetrating missiles incurred in war are a spe-
cial category. Carey, Young, Rish, and Mathis (30) re-
ported a 2 percent incidence of such abscesses. Rish and
colleagues (31) analyzed Vietnam data and found a 3
percent incidence (37 brain abscesses among 1221 pa-
tients with missile wounds to the brain). Many, but not
all, of those developing a late brain abscess had asso-
ciated retained bone fragments. More important than
retained bone alone, however, were concomitant orbital
facial wounds, wound complications, and multiple oper-
ative procedures on the brain.
Abscess from Adjacent Infection
Chronic infections of the ear, nose, and throat are po-
tential sources of infection that may spread to adjacent
brain. In one series, infections of the middle ear and
mastoid were the most common source (87 percent), fol-
lowed by the paranasal sinuses (12 percent) and tonsils (1
percent) (32). In another series, 45 percent of patients
with chronic mastoiditis (cholesteatoma) developed in-
tradural sepsis; the bulk of these complications consisted
of temporal lobe or cerebellar abscesses, and a smaller
number were supratentorial or posterior fossa subdural
empyemas. Acute mastoiditis was only occasionally (7
percent) associated with intradural infection (33). Al-
though antibiotics have drastically diminished the inci-
dence of intracranial extension of middle ear/rnastoid
infection, continued diagnostic vigilance concerning
such complications is recommended (34). Bacteria from
an adjacent infected paranasal sinus or mastoid may
reach the brain by direct extension from the involved
sinus through the underlying dura. Bacteria may also
reach the brain by local metastatic spread through ve-
nous channels that drain the sinus and enter the intracra-

nial compartment as emissary veins. Paranasal sinus in-
fections usually result in frontal lobe abscesses (Fig. 1).
Mastoid infections may cause temporal lobe or cerebel-
lar abscesses (35). Temporal lobe abscesses are more
common because the roof of the middle ear is thinner
than the posterior wall.
Scalp infection, infected subgaleal effusions, or cepha-
lohematomas may also lead to brain abscesses with or
without associated osteomyelitis. Bacteria from infected
bone of the skull (osteomyelitis) may spread directly into
the epidural space and reach the subdural compartment
and brain by direct extension through the dura. Bacteria
from a scalp infection or osteomyelitic bone also may
reach the subdural space and brain via emissary veins.
Cerebral abscess developing as a late complication of
cervical traction occurs rarely; this is thought to occur by
enetration of the inner table by the pins of the tongs or
18.10 unit (36).
Hematogenoas (Metastatic) Brain Abscess
These occur when bacteria from elsewhere in the body
colonize the brain. Blood—borne bacteria tend to flow
into the middle cerebral artery, so hematogenous ab-
scesses are usually located in the posterior frontal and
parietal lobes. Chronic pulmonary infections such as
bronchiectasis are an especially common primary source
FIG. 1. CT scan (with IV contrast), showing ring—enhance—
ment, of a 47-year-old man with right frontal brain abscess.
The patient presented with seizures. A craniotomy was per-
formed with drainage of the abscess. The patient initially did
well, but the abscess reaccumulated two weeks later and
was drained again. Frontal sinus infection was suspected as
the etiological source, and the brain abscess cleared after the
frontal sinus was exenterated.
CNS INFECTIONVS
of bacteria, but skin, pelvis, mouth, and long bones air
other underlying infective foci. Bacterial endoeaﬁSiis
may also lead to brain abscesses, particularly when heart
Valves are infected with Staphylococcus aareas or Group
D streptococci (37). In approximately one—fifth of
the cases no apparent source of infection can be
found (238).
Metastatic brain abscesses initially occur at the gray-
white junction, where blood flow in the brain capillary
bed is slowest, but what actually allows a bacterium to
adhere to and penetrate a brain capillary is unknown.
About 2 percent of all brain abscesses occur in patients
with cyanotic congenital heart disease (39). Individuals
with cardiac venous—to—arterial (V—A) or "right—to—left"
shunts are 10 times more likely than normal persons to
develop brain abscesses (17) because bacteria interrnit—
tently present in venous blood may bypass the lungs,
enter the arterial system, and pass to the brain. Most
cardiac V—A shunts arise as a consequence of Fallot's
tetralogy, or dextroposition of the great vessels. Further-
more, patients with cyanosis secondary to V—A shunting
are at greater risk of developing brain abscesses because
the associated elevated hematocrit increases blood viscos-
ity and reduces blood flow. This leads to rnicroinfarction
of the brain, which may then become colonized by bacte-
ria. Reduced tissue P02 concentration in these patients
also may enhance bacterial growth within the brain (17).
Patients with cyanotic, congenital heart disease also de-
velop strokes from thrornboernbolic disease. Some au-
thors believe that neurological signs and symptoms in
this population are more commonly caused by brain ab-
scesses than by vascular occlusion or hemorrhage (40).
They therefore advocate steps to immediately diagnose
brain abscess and to begin antibiotic therapy promptly
wltrerikpatierits with congenital heart disease develop a
s ro e.
Postmeningitic Brain Abscess
Considering the frequency of meningitis and the infre-
quency with which this type of abscess has been re-
ported, this complication of meningitis must be quite
rare in the antibiotic era. However, brain abscesses may
complicate pyogenic meningitis, presumably by direct
bacterial colonization of the brain. Neonatal meningitis
caused by Citrobacter is of particular concern, however.
because about 40 percent of these patients develop brain
abscesses (41,42). Antecedent brain softening, as from
Venous infarction, provides an excellent culture medium
for bacteria.
Pathology
Initially, a pyogenic brain abscess begins as a focal area
of bacteria—laden cerebritis. Host defense mechanisms

182 / CHAPTER 10
begin to wall off the infection by capillaiy proliferation
from the surrounding brain. Fibroblasts from the prolif-
erating capillaries lay down collagen fibers to contain the
purulent focus. Britt and colleagues (43,44) de1non-
strated five histological layers in brain abscess: zone 1, a
necrotic center; zone 2, an inflammatory infiltrate
mixed with macrophages and fibroblasts surrounding
the necrotic center; zone 3, collagenous capsule for1na-
tion; zone 4, cerebritis with neovascularity and perivas-
cular inﬁltration of inflammatory cells in the adventitial
sheaths of blood vessels surrounding the abscess; zone 5,
reactive astrocytes, gliosis, and cerebral edema. Brain
capillaries, from which ﬁbroblasts arise, are more nu1ner-
ous in the cortex and less plentiful in the white matter.
Abscess encapsulation, therefore, is more likely to be
complete superficially and deficient in the deeper white
matter. Experimental data suggest that hematogenous
abscesses are less well encapsulated than abscesses cre-
ated by direct bacterial implantation, possibly because
cerebral ischemia associated with metastatic abscess re-
tards capsule wall formation (45).
Britt and colleagues (43,44) studied experimental aer-
obic brain abscess formation and determined four devel-
opmental stages: early cerebritis (1-3 days); late cerebri-
tis (4-9 days); early capsule formation (10-13 days); and
late capsule formation. Whalen and Hilal's (46) clinical
data also indicated that brain abscess encapsulation re-
quires about two weeks. Britt and associates also studied
experimental abscess formation with Bacteroides, an an-
aerobic organism that proved_inuchjnore virulent than
aerobic bacteria. Animals infected with Bacteroides did
not survive into the late capsule formation stage. Viru-
lent bacterial infections of the brain parenchyma were
associated with extensive brain necrosis and edema. Gen-
erally, a brain abscess acts as an acute or subacute ex-
panding intracranial mass (47), often associated with
enormous reactive brain swelling. The combination of
the abscess mass and swelling may compress vital struc-
tures and may cause death by transtentorial herniation.
Because of deﬁcient encapsulation in the deep portion of
the abscess, it may extend centripetally and rupture into
the ventricle (48), causing fatal ventriculitis/meningitis.
Clinical Manifestations
Brain abscess presents chnically in various ways (39):
(l) The infections syndr0me—signs of infection, such as
pain, redness, and swelling about an infected frontal
sinus, may be local. Sometimes only general aspects
of infection may be evident, such as fever, elevated
white blood cell (WBC) count, neutrophilia, and in-
creased blood sedimentation rate.
(2) The intracranial hypertension syndr0me—papille-
dema, nausea, vomiting, and headaches.
(3) The syndrome offocal nenrologic signs—for exam-
ple, hemiparesis or dysphagia.
(4) The meningeal syndr0me—stiff neck.
(5) Psychic disturbances—especially an alteration in the
level of consciousness.
In general, headache is the most common presenting
complaint. Fever is present in only half of the patients.
Less than half have a focal neurological deficit, and nu-
chal rigidity is uncommon (1,2). The peripheral WBC
count is normal in 40 percent of the patients. A useful
diagnostic feature is the fact that the erythrocyte sedi-
mentation rate (ESR) is usually elevated, except in pa-
tients with cyanotic heart disease, in all of whom the
ESR is normally low owing to their polycythemia (2,47).
Signs and symptoms associated with a brain abscess vary
according to the location of the abscess, its size, and the
presence or absence of concomitant meningitis. Thus,
the affected individual may have headache, papilledema.
and an altered state of consciousness; motor, speech, or
visual disturbances; focal or generalized seizures; ataxia;
or signs of meningitis.
Brain abscesses are rare in the neonatal period (49,50).
Diagnosis of brain abscess in the neonate"is often diffi-
cult because few specific signs or symptoms Indicating
intracranial infection are present: fever is often absent
but vomiting or an enlarging head may be present (50).
Convulsions are the most constant clinical sign in these
young patients (51,52). In the series of Sutton and
Ouvrier (50), the clinical diagnosis of brain abscess was
suspected in only 2 of 12 infants. Sutton and Ouvrier
therefore recommended that an ultrasound, CT scan, or
both be done in all infants presenting with bacterial men-
ingitis.
Diagnostic Studies
When computerized tomography (CT) is available,
this is the primary screening modality for diagnosis of
brain abscess. Equally effective, though less widely avail-
able, is magnetic resonance imaging (MRI). Radionu-
clide (RN) brain scanning is also useful in diagnosis
when CT scanning is not available or is inconclusive.
Plain skull films of the head are generally of limited
value but may be useful in certain circumstances. Elec-
troencephalography (EEG) may provide evidence of a
localized space-occupying mass. Its use has largely been
replaced by CT or MRI scanning, when these are avail-
able. Lumbar puncture is often contraindicated because
of the high risk of cerebral herniation, but it may be
considered with neurosurgical consultation if meningitis
must be excluded. Angiography is now used rarely for
diagnosis of brain abscesses, except when modalities
such as CT or MRI are unavailable. Ultrasound may be
useful in identifying cerebral shift, especially in young

children when the more definitive diagnostic modalities
are unavailable.
Computerized Tomography
CT scanning has revolutionized the diagnosis of brain
abscess (Fig. l). The frequency with which CT identifies
brain abscesses reflects the prevalence of the disease in
the population. Michel (France) reported 19 brain ab-
scesses per 8,500 scans (0.2 percent) (53), and Danziger
(South Africa) observed 90 abscesses in 11,300 CT scans
(0.8 percent) (6). In addition to promoting early diagno-
sis, CT scanning allows the clinician to monitor the evo-
lution of the abscess before and after treatment. It has
allowed the successful treatment of abscesses in difficult
locations, such as in the thalamus or brain stem, and in
multiple brain abscesses (42,54,55).
One early study indicated that CT scanning had about
a 90 percent accuracy in diagnosing brain abscesses (56),
but it was noted that false negative CT scans were caused
by imaging artifacts, failure to give contrast media, and
scanning very early in the course of the disease, before
encapsulation had occurred. Use of contrast medium for
enhancement is mandatory in order to maximize the
diagnostic accuracy of the scan. CT scan of brain abscess
generally shows a ring—like pattern of smooth, uniform
thickness that encloses a hypodense region. The dense
ring, in turn, is surrounded by a hypodense area, presu1n—
ably cerebral edema. Ring enhancement has been attrib-
uted to breakdown of the blood—brain barrier (BBB), vas-
cular granulation tissueroriuxury perfttsion (57). Some
abscesses appear biloculate or septate on scans.
Ring enhancement on CT scanning may appear
within two days of the onset of neurological symptoms.
Experimentally (58,59), a ring pattern consistent with
abscess also has been observed in localized cerebritis
(60). Abscess "encapsulation" demonstrated by CT
scanning may not correspond to histologic encapsula-
tion; CT ring enhancement was seen with either cerebri-
tis or brain abscess (61). This observation is ofrnore than
theoretical interest for two reasons: first, if a diagnosis of
brain abscess was made by CT scan but nothing could be
aspirated by needle tapping because the ring—enhancing
image was really cerebritis, additional brain damage
could result from repeated cannulations in search of the
abscess. Secondly, cerebritis is more amenable to antibi-
otic treatment than is a brain abscess. Possibly some of
the reported cures of brain abscess from antibiotic ther-
apy alone were in reality cures of cerebritis.
Even under experimental conditions, investigators ini-
tially had difficulty distinguishing cerebritis from abscess
by CT (59). Clinical and experimental studies have distin-
guished between cerebritis and frank brain abscess by
means of serial CT scans (58,62). In order to stage the
brain abscess by this method, patients were given about 2
CNS INFECTIONS / 183
ml/kg of contrast medium intravenously. CT scans were
then obtained at 5, 10, 20, 30, 45, and 60 minutes after
injection. With cerebritis, the ring of enhancement in-
creased for the first 10 to 20 minutes, then plateaued for
an hour. The enhancing ring was thick and diffuse when
first seen about the periphery of the lesion. With time,
the ring tended to migrate toward the center of the le-
sion, which sometimes did not fill in with contrast. Brain
abscesses, on the other hand, showed rapid ring contrast
enhancement by 5 to 10 minutes and rapidly faded by 30
minutes. Steroid administration may decrease CT en-
hancement of brain abscesses in their early stages (63),
but attenuation of CT ring enhancement of a brain ab-
scess with steroid rnust not be misinterpreted as resolu-
tion of infection (64).
Cystic glioina, tumor metastases, and infarct are coin-
mon lesions that may mimic abscess on CT scans. Gho-
rnas and metastases tend to have more irregular capsules
when enhanced, but nevertheless, their CT image may
be confused with that of an abscess. In one recent analy-
sis, "malignant tumor" was the initial scan diagnosis in 8
of 26 instances of proven brain abscess (65). Rapid
changes on sequential CT scans favor infection. Provid-
ing clinical history to the radiologist may improve the
accuracy of CT diagnosis.
CT scanning has proved to be an effective means for
following patient progress after treatment. Some investi-
gators believed that abscess capsule enhancement seen
on CT diminished after drainage and that reduced en-
hancement indicated successful treatment. Conversely,
persistent capsule enhancement on follow—up CT studies
was thought to indicate that the abscess had refilled or
extended (56). Subsequent studies, however, have indi-
cated that even after complete, successful surgical exci-
sion of the abscess, a ring—like zone on contrast enhance-
ment surrounding a low—density zone may be present for
some time (57). Eventually, however, this post—excision
ring gradually fades and the excision site is marked only
by a region of low cerebral density. Although this persis-
tent ring tends to be more irregular than most abscess
capsules, differentiation from recurrent abscesses may
require considerable clinical acumen plus further se-
quential CT scans.
Magnetic Resonance Imaging (MRI)
MRI is effective in demonstrating brain abscesses as
well as other infections of the brain (66). This imaging
modality is more sensitive than CT in detecting the se-
quential changes in the development of a brain abscess
(67). Brant—Zawadzki and associates (68) compared
MRI and CT imaging of experimental brain abscesses.
In the cerebritis stage, CT scans showed ring enhance-
ment corresponding to the inflammatory zone and a
surrounding large area of low attenuation. Spin—echo

184 / CHAPTER 10
MRI showed high intensity in both the dense inflarnrna—
tory zone and surrounding edematous brain. This high
intensity area on MRI was more extensive than brain
changes demonstrated by CT. The central core of the
abscess was represented on the MRI by a lower intensity
area. CT scanning of encapsulated abscesses showed dis-
crete ring enhancement of the capsule, and the spin—echo
MRI showed a more circumscribed, peripheral, high—in—
tensity area. The authors suggested that MRI is more
sensitive than CT in the early detection of cerebritis as
well as adjacent cerebral edema (68). CT and MRI
proved to be equal in detecting the development of cen-
tral necrosis within an abscess. MRI could differentiate
tissue liquefaction from simple edema because edema is
seen as an area of high intensity on spin—echo images,
while liquefaction is shown as a low intensity region.
Capsule staging was better assessed by CT scanning.
Repeated imaging is necessary to follow the course of
an abscess; in this regard, an advantage of MRI is the
absence of radiation exposure. Gadoliniurn—DPTA, a
paramagnetic contrast agent, enhances MRI imaging as
a function of penetration of the BBB (69).
Radionuclide (RN) Scans
Radionuclides penetrate the BBB in the presence of
inflammation. This alteration allows large molecules
tagged with a radioactive moiety to penetrate the BBB
and accumulate in the region of a lesion. Isotopic brain
scans accurately identify 90 percent of all supratentorial
abscesses. PosteriortossaTesions may be missed, how-
ever, because of the overlying suboccipital muscles that
also take up the isotope. Radioisotope is concentrated in
the abscess capsule and surrounding brain (70). The oc-
casional occurrence of the "ring" or "doughnut" sign
may suggest a brain abscess as the isotope is taken up by
edematous brain and capsule but not by the pus within
the abscess. Although RN scans may not distinguish be-
tween abscess, cerebritis, or neoplasm, they may delin-
eate early cerebritis and diffuse intracranial infection
better than CT scans do (71), and therefore RN and CT
scans may be considered complementary tests (72). In
one series, RN delineated eight of eight brain abscesses
and CT delineated seven of the eight. Conﬁdence in RN
is important because this diagnostic tool may be avail-
able in areas where the more expensive CT is not. The
use of technetium"m—DPTA with delayed scans en-
hances the diagnostic sensitivity of RN scans even fur-
ther (73).
Skull X-Rays
These are helpful and may show such contiguous
sources of infection as osteomyelitis of the skull or sinus/
mastoid disease. A shift of the pineal indicates an intra-
cranial space—occupying mass. Rarely, gas—forming bacte-
ria within an abscess may cause diagnostic lucencies on
skull films.
Electroencephalography (EEC)
This modality may be a useful screen for brain abscess
because of the characteristic focal, low—frequency delta
wave associated with this lesion. Although diagnosis by
EEG cannot be expected to be as precise as CT or MRI
scanning, EEG is useful in situations when CT or MRI
scanning are not available. In one recent series, EEG
predicted ll of 13 abscesses, radioisotopic brain scans
localized five of six abscesses, and carotid arteriograms
localized six of seven lesions (74). Michel compared the
efficacy of EEG and CT scans (53). Among 19 cases,
EEG patterns typical of brain abscesses were seen in 6
(32 percent), and CT images diagnostic of abscess oc-
curred in 13 (68 percent).
Lumbar Puncture
This test should not be performed when a brain ab-
scess is suspected because it may lead to transtentorial or
tonsillar herniation; furthermore, it rarely provides bacte-
riological data because brain abscesses only occasionally
shed organisms into the subarachnoid space. Risks of
this procedure in the evaluation of a brain abscess out-
weigh its beneﬁts (2,4,5,47,75).
Cerebral Angiograplty
Cerebritis results in a characteristic capillary and early
venous blush. This angiographic blush is possibly caused
by increased cerebral perfusion associated with inflarn—
mation in addition to the accumulation of contrast in
dilated capillaries about the involved area. The angio-
graphic diagnosis ofbrain abscess is made by evidence of
a mass lesion and cerebritis. Evidence of leptorneningeal
inflammation is indicated by the pooling of contrast
within sulci and by halo formation about arterial struc-
tures. There is also angiographic staining of neovascular
tissue within the abscess (the "ring" sign) (76,77). When
CT or MRI scanning is not sufficiently diagnostic, arteri-
ography may differentiate tumors from abscesses if neo-
vascularity typical of tumor vessels is seen within the
mass lesion.
Ultrasound
Yang found echoencephalography 87 percent accu-
rate for lateralizing supratentorial abscesses (5). Occa-
sionally, ultrasound is capable of visualizing an abscess

wall. This technique may prove particularly useful for
abscess diagnosis in infants with open fontanelles.
Organisms Causing Pyogeriic Brain Abscess
Streptococci and staphylococci are the most frequent
cause ofpurulent brain abscesses (1,78—83). In the antibi-
otic era, more mixed infections caused by gram—positive
cocci and gram—negative rods have appeared. S trept0c0c—
casfaecalis, Proteus, and Bacteroidesfragllis are the
organisms most commonly implicated in polyrnicrobial
otogenic abscesses (84). Clostridium is the organism
most commonly found in postcraniotomy infec-
tion (84).
Anaerobic bacteria have been increasingly recognized
as sources of infection of the CNS, owing to improved
methods of isolation and identification. The importance
of anaerobic organisms has been recognized since Heine-
man and Braude's study demonstrated their frequency
in brain abscesses (85). In another study, anaerobic bacte-
ria were isolated from 70 percent of the brain abscesses
(86). Bacteroides species, anaerobic streptococci, and fu-
sobacterium, either singly or in combination, are the
most common anaerobes that cause brain abscesses
(43,80,86—89). Bacteroidesfragilis is an obligate anaer-
obe that tends to produce brain abscesses, especially
those following chronic middle ear and mastoid infec-
tions. The outer cell wall membrane of B. fragilis reacts
with serum complement, which compjelelyabor'ishes
polymorphonuclear rnovernentrTTTis may give the bacte-
ria enough time to replicate and overwhelm host de-
fenses. These organisms also produce endotoxins, hepa-
rinase, collagenase, and hyaluronidase, which may
account for their virulence. Patients with chronic dis-
eases and patients who are immunosuppressed are more
likely to have brain abscesses caused by unusual bacte-
ria, such as Listeria monocytogenes, or by fungi. The
protozoa Toxoplasma gondii is a common cause ofCNS
infection in patients with AIDS (90,91).
Antimicrobials
Antirnicrobials exert their antibacterial effects in a va-
riety of ways. Some, such as the penicillins (92), cephalo—
sporins (93), and vancomycin (94) inhibit bacterial cell
wall synthesis. Others, such as the aminoglycosides (in-
cluding streptomycin) (95), tetracyclines (96), Chloram-
phenicol (96), erythromycin (97), and rifampin (98) in-
hibit RNA synthesis. Chloramphenicol is bacteriostatic
because it inhibits microbial protein synthesis by inhibit-
ing peptidyltranferase. This action blocks polypeptide
formation at the ribosomal site in the endoplasmic reticu-
lum but does not produce irreversible cell damage. Met-
ronidazole is bactericidal and damages bacterial DNA or
other molecules (99). The sulfonamides inhibit intrabac—
CNS INFECTIONS / 185
terial folate synthesis (100). The polyrnyxins interact
with cell—wall phospholipids and act as cationic deter-
gents or surfactants, and they increase the permeability
of the bacterial cell wall (101); however, those agents are
obsolete today and are no longer used.
Penetration of substances across the BBB is propor-
tional to their lipid solubility (102,103). Antibiotics with
greater lipid solubility pass through the BBB more
readily than do non—lipid—soluble ones. Nonionized mol-
ecules pass through the BBB more readily than ionized
molecules do. Penicillin G is nonlipophilic and is highly
ionized at physiological pH. Hence, penicillin and other
beta—lactam antibiotics do not cross the normal BBB
well. With inflammation, the BBB breaks down, allow-
ing penicillin to enter brain extracellular space.
Antibiotics highly bound to plasma proteins have low
effective plasma concentrations, and consequently, pas-
sage of protein—bound antibiotics across the BBB is poor.
High molecular weight and complex antibiotic molecu-
lar structure also impede BBB crossover. This latter fac-
tor may help explain the poor passage of the arninoglyco—
sides from blood to brain. Even with meningitis,
penetration of the arninoglycosides can be achieved only
by intrathecal administration (95). In neonates, how-
ever, arninoglycosides do penetrate the CSF in adequate
concentration. These factors indicate why antibiotics ac-
cumulate poorly in the CNS. Theoretically, active trans-
port mechanisms within the BBB might enhance the
passage of some antibiotic molecules from plasma to
brain extracellular space.
Clinical data have shown that CSF tetracycline levels
are 10 to 20 percent ofplasma levels (96). Under normal
conditions, CSF erythromycin is 0 to 2 percent of the
plasma level. With meningitis, however, the CSF con-
centration of this drug may increase to 5 to 10 percent
that of plasma. Normally, vancomycin does not cross
from plasma to CSF, but in the presence of meningitis,
bactericidal levels of the drug may be found in spinal
fluid. Despite this fact, up to 3.0 to 5.0 mg of vancomy-
cin may be given intrathecally to combat infection if no
response to parenteral administration occurs (94).
Whereas "first generation" and most "second genera-
tion" cephalosporins do not cross the BBB well, cefurox—
ime, a "second generation" cephalosporin, and all "third
generation" cephalosporins cross the BBB readily (93).
Chloramphenicol is 60 percent protein—bound in
plasma. CSF/plasma ratios of the drug vary from 35 to
65 percent regardless of the administration route and the
degree of meningeal inflammation. Because the level of
protein in CSF is so much lower than that in plasma,
Chloramphenicol may be relatively more active in CSF
than in blood (104). Most of the organisms involved in
brain abscesses are susceptible to Chloramphenicol. Phe-
nytoin may increase the effective serum chlorampheni—
col concentration (even into toxic ranges), but pheno-
barbitol may decrease it (105). The penicillins are

186 / CHAPTER 10
bactericidal for 1nost of the co1n1non pathogenic bacte-
ria, but some pneumococcal and group B streptococci
may be resistant. Metronidazole is soluble in water and
is essentially nonionized at physiological pH. This 1nole—
cule, therefore, rapidly crosses the BBB and cell mem-
branes to achieve anaerobicidal concentrations in the
CSF. It is excreted in the urine. A transient opening in
the BBB may be induced to allow substances that ordi-
narily do not pass the barrier into the brain extracellular
space (106). Neuwelt increased gentainycin delivery to
the brain 30- to 45 —fold in rats by giving the drug directly
into the carotid artery following BBB opening by 1nanni—
tol (107). This approach may have human application.
Human data suggest that penetration of antibiotics
into brain abscesses is unpredictable (80). Fusidic acid
has "good" abscess accumulation. Chloramphenicol, be-
ing a small molecule, penetrates the normal BBB well,
but unfortunately its uptake into abscesses has been er-
ratic. Penicillin and ampicillin penetrate abscesses rea-
sonably well, and third—generation cephalosporins pene-
trate to produce adequate concentrations.
Black, Graybill, and Carache documented six cases
where antibiotics penetrated abscesses in reasonable
concentrations, yet the patients continued to deteriorate
until surgical treatment was undertaken (108). They
concluded that antibiotics failed once they had reached
the contents of the abscessjggcause of poor antibiotic
activity within the lesion. They hypothesized that the
purulent milieu within the abscess inhibited antibiotic
effectiveness.
Experimental evidence suggests that steroid adminis-
tration in the treatment of experimental brain abscesses
retards the passage of some antibiotics through the BBB
and into the region of infection. These data suggest that
antibiotic dosages should be increased to optimize drug
tissue concentrations if steroids are used to treat the
edema associated with brain abscesses.
Knowledge of the original infective source—even be-
fore the organism has been identified—is useful when
selecting initial antibiotic therapy because speciﬁc organ-
isms are commonly associated with certain inciting foci.
According to DeLouvois (109), abscesses of sinusitic ori-
gin are often caused by carboxyphilic streptococci, fre-
quently Streptococcus milleri, which are highly sensitive
to penicillin. Penicillin (16 to 24 megaunits/24 hrs),
therefore, should be included in the treatment of brain
abscesses of sinusitic origin. However, mixed aerobic
and anaerobic organisms (such as Bacteroides) resistant
to penicillin have been cultured from sinus infections
(110). Therefore, it may be advisable to treat abscesses of
sinusitic origin with metronidazole in addition to peni-
cillin. Abscesses from mastoid infection are caused by a
wide range of aerobic and anaerobic bacteria. Penicillin,
chloramphenicol, and metronidazole (88,111,112), or
ampicillin, gentamycin, and metronidazole should be
started intravenously when treating otogenic brain ab-
scesses because of the high probability of mixed gram-
positive, gra1n—negative aerobic and anaerobic bacteria,
including Bacteroides. For gra1n—negative organisms, ce-
fotaxime and ceftriaxone are highly effective. In so1ne
cases, clavulanic acid, combined with ticarcillin, has also
been recommended (113). Posttraumatic abscesses are
frequently caused by Staphylococcus aureus (109). Naf—
cillin would be a good initial antibiotic choice for these
abscesses, before speciﬁc antibiotic sensitivity testing has
been completed. If methicillin resistance is suspected,
vancomycin should be used pending sensitivity testing of
the isolate.
In rare instances when the organisms are resistant to
other antibiotics, quinolones may be effective by virtue
of their satisfactoiy penetration into the CNS. Peﬂoxacin
(not available in the United States) and ciprofloxacin
(available in the United States only in oral form) are two
quinolones that may be considered in these cases (114).
There are, however, no clinical data on the utility of
these agents in brain abscesses.
Duration of Antibiotic Treatment
For aerobic bacterial abscesses, six weeks of antibiotics
is advisable, and for anaerobic abscesses, 8 to 16 weeks is
recommended (115). The majority of abscesses are
mixed aerobic—anaerobic infections; intravenous antibi-
otic therapy is recommended for four to eight weeks
(116), and depending on the response, an additional four
to eight weeks of oral therapy may be given. Fungal brain
abscesses require antibiotic therapy for months (116).
Toxoplasma gondii brain abscesses in patients with
AIDS are treated indefinitely (116).
Treatment
Surgical Treatment ofBrain Abscesses
Brain abscesses have been treated 1nost commonly by
drainage, aspiration, excision, or a combination of these
methods. Drainage procedures, in which a tube is placed
into the abscess cavity, were the first to be used syste1nati—
cally (117). Dandy introduced the technique of abscess
aspiration by one or multiple taps through a burr hole
(118), and Clovis Vincent, in the 1930s, advocated exci-
sion via formal craniotomy after encapsulation (119).
Following the introduction ofpenicilhn, LeBeau de1non—
strated that areas of cerebritis (unencapsulated ab-
scesses) could be excised (120). Reduction of abscess size
by tapping or drainage in the acute phase, followed by
excision of the residual capsule, was also advocated at
one time (121). Thorotrast, pantopaque, and micro-
paque barium have been used in the past to visualize
abscess cavities so that capsule shrinkage after drainage
or aspiration could be followed on serial skull films.

Such markers should not be used when CT scanning is
available for follow—up, because these substances inter-
fere with scan image. One treatment method involves
craniotomy, wide abscess incision, and pus drainage
under direct vision. With this technique, the empty ab-
scess is inigated with antibiotic solution and left in sita.
In one series, 15 consecutive cures were reported by this
technique with little morbidity (122). However, there
would appear to be no particular benefit of this tech-
nique over the method of needle aspiration (2,75).
The mortality data do not suggest strongly that one
treatment type is inherently better than another. In view
of the fact that the most immediate threats of a brain
abscess are its space—occupying mass and reactive brain
swelling, the primary role of surgical intervention is to
alleviate the increased intracranial pressure. This can be
achieved by any of the methods in current use. Although
the choice is controversial at present, the method is prob-
ably less important than tﬁ of increased ICP by
any means before irreversible brain damage has occurred
(2,75). Although abscess excision may appear logical be-
cause the brain infection is totally removed, this form of
therapy is usually reserved for patients who have inan-
aged to wall offthe abscess. Furthermore, patients consid-
ered for abscess excision are more often alert and in satis-
factory neurological condition, indicating a more
optimally functioning brainstem. Brain abscesses con-
taining gas are probably best treated by open craniotomy
and excision if it appears that the abscess is related to a
sinus or mastoid infection or trauma, because the air
may result from a dural tear rather than gas—producing
bacteria. Not only will the abscess have to be excised, but
the dural defect will have to be closed (123). Simpler
procedures such as drainage or aspiration are more often
used with neurologically compromised patients or with
patients who have surgically inaccessible lesions involv-
ing the thalamus, basal ganglia, or brainstem. The seri-
ous disadvantage of drainage or tapping is that a 1nultilo—
cated abscess may be incompletely treated. However, CT
scanning, perhaps with the use of CT/stereotactic guid-
ance, should enable targeting of such multifocal lesions
for needle aspiration. Furthermore, CT scanning can
provide the surgeon with follow—up status of the lesion
with repeated aspiration.
It would seem reasonable to suggest, therefore, that
needle aspiration, with CT/stereotactic guidance, may
be the preferred form of initial management in the fu-
ture. This may be followed by excision if aspiration
should fail. Whatever form of therapy is initially se-
lected, the brain abscess may reaccumulate. It is advis-
able to observe the patient clinically and obtain repeated
follow—up CT brain scans over a period of months and to
manage the patient accordingly.
The surgical treatment of brain abscesses from cya-
notic congenital heart disease has proven especially diffi-
cult. Kagawa and associates (124) treated 17 patients
CNS INFECTIONS / 187
with this condition by excision following aspiration with
no mortality. Despite their success with aspiration fol-
lowed by excision, they believe that in the future, simple
CT—guided aspiration alone may suffice.
There is no conclusive evidence of any difference in
postoperative seizure frequency following excision ver-
sus tapping or drainage (125,126). Abscesses in the tern-
poral lobe or in the motor/sensory area of the brain are
more likely to lead to the development of seizures than
are lesions involving the frontal or occipital areas.
Although various forms of surgical care may be effec-
tive, the mortality is much lower when patients are in
satisfactory neurological condition, as manifested by
level of consciousness. Mortality doubles, triples, or qua-
druples as the level of consciousness decreases, reflecting
brainstem compromise from uncal or tonsillar hernia-
tion. The obvious conclusion is that for optimal neuro-
logical results, a brain abscess must be treated before it
has caused irreparable brainstem damage consequent to
its mass effect with increased intracranial pressure.
Medical Treatment 0fBrain Abscess
Past experience has indicated that surgery is the ap-
propriate treatment for brain abscesses. Nevertheless, in
1971, Heineman, Braude, and Osterholm reported the
successful antibiotic treatment of six patients with pre-
sumed brain abscesses (l27). Each patient had neurologi-
cal signs and, in some cases, EEG findings suggestive of
localized intracranial infection. Chow and colleagues, in
1975, reported the successful antibiotic treatment of a
patient presumed to have multiple Listeria m0n0Cyt0—
genes brain abscesses (128). Traditionalists who believed
that pus must be drained or otherwise removed surgi-
cally viewed these reports with sorne skepticism. Because
no surgical intervention occurred and no histologic speci-
men existed, the possibility remained that these inedi-
cally cured "abscesses" were, in reality, areas of cerebri—
tis that antibiotics might be expected to penetrate and
cure. Black, Graybill, and Carache did not have success
with antibiotics alone in the treatment of surgically con-
firmed brain abscesses (l08); antibiotics penetrated the
abscesses adequately, yet viable bacteria were subse-
quently cultured frorn them, possibly because pus inter-
fered with antibiotic activity.
The development of CT scanning made earlier diag-
nosis of brain abscesses more routine, because direct vi-
sualization of the lesion was possible. The course of the
abscess could be followed while antibiotics were adrnin—
istered, presumably in preparation for surgery. Reports
began to appear on occasion of abscesses cured by antibi-
otics alone (l29—l36). Computed tomography was used
to diagnose and follow the abscesses in most patients, but
radionuclide imaging was used once. Although these re-
ports appear encouraging, experiments on dogs by Enz-

188 / CHAPTER 10
1nann, Britt, and Yeager correlated CT scans with l1isto—
logic features and indicated that cerebritis may appear
with a peripheral enhancing ring on CT scans and may
be confused with a true abscess (58). Thus, so1ne of the
1nedical cures of "brain abscesses" may have been cures
of cerebritis instead. This caveat notwithstanding, a
growing number of clinical reports have appeared that
indicate that so1ne brain abscesses diagnosed and fol-
lowed by CT may be cured by antibiotics alone. Petit
reported only 1 death among 14 cases of brain abscess
treated with antibiotics alone (136). Only four of these
patients had abscesses larger than 4 cm in diameter. The
number of 1nedical cures of brain abscesses is low. Fur-
thermore, when 1nedical therapy has been conscien-
tiously tried, it has succeeded only about 60 percent of
the time. Antimicrobials alone are 1nore likely to be suc-
cessful if the abscess is less than 3 c1n in diameter and if
antimicrobials are started early (88,137,138).
Rosenblum and coworkers reported successful treat-
ment in 6 of 10 patients with antibiotics alone and sug-
gested that medical management be undertaken for sur-
gically high—risk patients in good neurological status
(137). Such patients include those with congenital heart
disease or multiple or deep—lying abscesses and those
with concurrent meningitis, ependymitis, or hydrocepha-
lus requiring a shunt. A study that investigated 102 pa-
tients with brain abscesses between 1970 and 1986 sug-
gested that although medical therapy is appropriate in a
few patients, surgeiy remains the definitive approach for
diagnosis and treatment of1nost brain abscesses (139). In
undertaking the 1nedical treatment of brain abscess, pen-
icillin G and chloramphenicol, with or without genta1ni—
cin, are started, and periodic CT scans are obtained. Al-
ternatively, initial treatment may consist of a
combination of metronidazole and cefotaxime (or cef-
triaxone or ceftazidime); the combination of 1netronida—
zole and cefotaxime covers the co1n1non causative organ-
isms in brain abscesses and avoids the toxicity of
chloramphenicol and gentamicin (140). After two weeks
of treatment, the patient is rescanned. Surgeiy is under-
taken if the abscess has enlarged, if signiﬁcant 1nass effect
is present, or if neurological deterioration has occurred.
Ifthe clinical course is stable or improving, antibiotics
are continued for two additional weeks. The patient is
rescanned weekly or whenever warranted by new sy1np—
toms. Surgeiy is performed if the abscess has not de-
creased in size after four weeks. If the abscess does de-
crease in size with medical management, antibiotics are
continued for six to eight weeks, and CT scans are done
for as long as a year to ensure that the abscess does not
recur. Whalen and Hilal presented a seiies of 20 brain
abscesses, seven (35%) of which were cured with antibi-
otics and without surgeiy (141). They argue that two
further criteria should be fulfilled when starting and con-
tinuing the medical management of brain abscesses: (1)
the absence of increased intracranial pressure; and (2) a
good clinical response to medical treatment within the
first week of therapy.
If medical treatment of a brain abscess is to be under-
taken, it is recommended that a neurosurgeon be con-
sulted and that the patient be followed closely in collabo-
ration with a specialist in infectious diseases who is
knowledgeable about available antibiotics and their po-
tential f or blood—brain barrier and brain abscess penetra-
tion. Neurosurgical iI1t61'V6I1tlOI1 may have to be consid-
ered in the event of clinical deterioration.
Steroids and Brain Abscess
Steroids have been found useful in the treatment of
cerebral edema associated with brain tumors (142,143).
Pyogenic brain abscesses are generally associated with
significant cerebral edema, and there is a question re-
garding use of steroids to control the cerebral edema,
especially because the 1nass effect of the swollen, ede1na—
tous brain may contribute to fatal cerebral herniations.
Steroids, however, are known to decrease the immune
response consequent to infection, and the possibility ex-
ists that their use could exacerbate intracranial infec-
tions.
long and Meachem examined the effect of steroid ad-
ministration upon experimental brain abscess encapsu-
lation (144). They concluded that dexamethasone may
retard but not eliminate abscess capsule formation.
Quartey, Johnson, and Rozdilsky also examined the ef-
fect of glucocorticoids on experimental brain abscesses
histologically and determined that steroids did indeed
retard capsule formation, but they noted less edema of
the adjacent tissue (145). Thus, steroids showed two op-
posing effects. Reduction of surrounding edema was
beneficial, but retardation of capsule formation was dele-
terious because viable bacteria remained in the brain.
Wallenfang, Bohl, and Kretzschmar used an expe1imen—
tal cat model to assess physiologically and histologically
the problem of abscess encapsulation, associated brain
edema, and the effects of steroid administration (146).
Steroids (0.5 mg dexamethasone/kg) markedly amelior-
ated brain edema in adjacent and distal brain. Abscess
encapsulation was ObS61‘V6Cl, but cats treated with antibi-
otics and glucocorticoids exhibited a weaker formation
of the mesenchymal inflammatory infiltration (59).
Lyons and associates studied the effect of sho1t—term,
high—dose co111'costeroids on CT enhancement of expen-
mental brain abscesses and concluded that the use of
high—dose (1.2 1ng/kg), short—te1m (12 hour) co111'coste—
roids did not appear to alter significantly the evolution of
intracranial abscess. Histologically, however, they did
0bS€1'V€ "so1ne changes" in the amount of collagen depo-
sition (147). Neverrheless, these investigators could not
ascertain whether the high—dose, sho1t—term steroid ad-
ministration hindered capsule formation. Enzmann and

colleagues studied the effect of dexamethasone (1.8 rngl
kg) given over 48 hours on the encapsulation of experi-
mental brain abscesses. These authors concluded that a
"48—hour course of steroid administration had no notice-
able effect on histology of experimental brain abscesses,
either in the cerebritis or capsule stage" (63).
In the clinical setting, the use of steroids in the treat-
ment of brain abscess is controversial (148); some avoid
their use for fear of decreasing the inflammatory re-
sponse and hindering encapsulation (145), but others be-
lieve that steroids are beneficial (149,150). CT scanning
may allow each case to be individualized. If surrounding
brain edema is severe and poses a risk of neurological
deterioration, steroids (along with prompt surgical treat-
ment) are recommended because, experimentally, they
have been shown to reduce the edema associated with
the abscess. It has been suggested that the use of steroids
is reasonable when the pathogen is known and specific
antibiotic therapy is given concurrently (2,75). If, on the
other hand, the abscess is relatively small (less than 3 cm)
and is not associated with brain edema, antibiotics may
be given without steroids.
Current Mortality Associated with Brain Abscess
In the early part of the antibiotic era, the mortality
associated with brain abscess remained surprisingly high.
In some series, lower mortality was achieved by aggres-
sive diagnosis, timely surgery, close postoperative sur-
veillance, and improved antibiotic usage (1,151,152).
From 1946 to 1977, surgical mortality ranged from 20 to
60 percent. Introduction of CT scanning of the brain in
the mid 1970s provided a means of earlier diagnosis;
Rosenblum and associates attributed 0 percent mortality
in their series to this new diagnostic modality (153). A
similar series showed a mortality of 20 percent among 15
cases in which CT scans were used; of the three deaths,
two followed antibiotic therapy alone and one followed
combined antibiotic and surgical management (154).
On the other hand, Dohrmann and Elrick observed that
the advent of CT scanning had no apparent effect on
brain abscess mortality (29). It would appear that, apart
from early diagnosis and possible surgery, the identifica-
tion of the oﬂending organism and selection of appro-
priate antibiotics are of paramount importance in reduc-
ing mortality and morbidity (2). The information
provided by the CT scan regarding the status of the ab-
scess and the surrounding brain does offer the neurosurg-
eon and other involved clinicians greater latitude in inan-
agement in deciding whether to pursue a vigorous course
of antibiotic therapy, to tap, drain, or excise the abscess,
or to tap and allow further encapsulation before later
excision. If CT scanning is unavailable, clinical judg-
ment plus the relatively accurate diagnostic modalities of
EEG, radionuclide scanning, angiography, and ultra-
CNS INFECTIONS / 189
sound in infants should permit early diagnosis and de-
creased mortality.
Sequelae ofManagement
Gruszkiewicz and associates reported a 12 percent in-
cidence of neurological sequelae—hemiparesis, seizures,
hemianopsia, and aphasia—among 50 survivors (155).
In Nielsen's series, only one—third of 67 patients showed
complete neurological recovery (156).
In another series, 15 to 30 percent of survivors had
paresis, and 10 to 20 percent had varying degrees of
speech and language defects (157). As expected, parietal
abscesses are more prone to be associated with such defi-
cits (15 6). Some postabscess disability may be expected
in 30 to 50 percent of all patients, whereas total disability
occurs in 7 to 17 percent (125 ,157). The quality of sur-
vival may be poorer in children (50,157). Nielsen ob-
served that 29 percent of children, but only 9 percent of
adults, had severe epilepsy and that 33 percent of chil-
dren, but only 13 percent of adults, demonstrated intel-
lectual reduction following a brain abscess (15 6). Hirsch
and colleagues, on the other hand, found that almost
three—quarters of children who survived their brain ab-
scesses were essentially normal (158).
Seizures occur in 15 to 55 percent of survivors, but up
to 73 percent may report seizures if they are followed up
for long periods (126,159). Frontal and temporal ab-
scesses are more frequently associated with epilepsy
(156). In some series, seizure development was indepen-
dent of the mode of surgical therapy (125,157), but in
one review, aspiration of the abscess had less of an associ-
ation with late epilepsy (156). Postabscess epilepsy has its
peak incidence four to five years after abscess occurrence
and treatment and may lead to death in a small percent-
age of those who survive their abscess. Because of this,
anticonvulsants should be continued for five years after
successful brain abscess therapy. Despite the large nurn—
ber of drugs available, medical control of epilepsy fails in
about 25 percent of cases (15 6).
With respect to cerebellar abscess, neurological se-
quelae following successful treatment may be minimal
(5 ,35 ,160).
Actinomycosis (161-165)
Actinomycosis is a noncontagious, suppurative, bacte-
rial infection characterized by chronic inflammatory in-
duration, sinus tract formation, fever, and leukocytosis.
Actinomyces israelii is responsible for the majority of
human actinomycotic infections. Once known as the
"ray fungus," A. israelii is now recognized as a gram-
positive, non—acid—fast anaerobic eubacterium, interrne—
diate between classical bacteria and higher fungi. Unlike
Nocardia, Actinomyces have not been isolated from the

190 CHAPTER 10
soil. The bacteria reside in natural cavities of humans
and animals, particularly in the mouth. The endogenous
organism gains entry to the body via breaks in the mu-
cous membranes. Involvement of the CNS (1 to 15 per-
cent of cases) occu1s by hematogenous spread fro1n a
pulmonary focus or by direct spread fro1n lesions involv-
ing the skull, face, and throat, possibly via lymphatics.
Aciinomycetales streptomyces brain abscesses in AIDS
patients have been reported.
Signs and symptoms of an actinomycotic brain ab-
scess depend upon location and may include focal neuro-
logical findings as well as increased intracranial pressure.
Actinomycotic brain abscess occurs 1nore often than
meningitis and subdural e1npye1na caused by that organ-
ism. Specific diagnosis can be 1nade by the de1nonstra—
tion of basophilic or amphophilic "sulfur granules" on
microscopic examination of tissue exudates. The organ-
isms are not visible on hematoxyhn and eosin sections
but may be seen with the Gomori stain. The organisms
grow anaerobically.
Surgical aspiration or excision plus penicillin, 2 to 20
million units per day for 6 to 18 months, forms the basis
of treatment. A 28 percent mortality has been reported
in cases adequately treated with antibiotics and surgeiy.
Poor prognosis is related to an inteival of greater than
two months before diagnosis and treatment.
Nocardiosis (166-170)
Nocardia are strictly aerobic, gra1n—positive fila1nen—
tous bacteria with an unusual propensity to spread fro1n
a primary pulmonary focus to the brain. The 1nostco1n—
mon species to infect humans is Nocardia asteroides.
CNS involvement, usually as a parenchymal abscess or,
uncommonly, as a leptomeningitis, occurs in 20 to 30
percent of patients with nocardia. A case of nocardia
abscesses complicated by a mycotic (infected) cerebral
arteiy aneurysm has been reported. In the United States,
75 percent of nocardial infections occur in i1n1nunoco1n—
promised persons. The overall mortality of cerebral no-
cardiosis is 80 percent, largely because this disease occurs
in people with serious underlying disease (e.g., AIDS pa-
tients and patients with immunosuppression associated
with malignancies or following treatment for organ
transplantation).
For nocardia brain abscesses, surgical aspiration or ex-
cision, combined with antimicrobial therapy, forms the
basis of treatment. Sulphonamides are the drug of
choice: this treatment should be continued for at least
one year. Good prognostic predictors in cerebral nocar-
diosis include early diagnosis, appropriate chemother-
apy, limited brain involvement, and, 1nost importantly,
the absence of seiious underlying disease. At least one
case of cerebral nocardia brain abscess has been suc-
cessfully treated medically, using CT to follow abscess
resolution.
Multiple BrainAbscesses
Before 1975 the incidence of multiple brain abscesses
reported in various series ranged from 4 to 13 percent.
Since the advent of CT brain imaging, the reported inci-
dence of multiple brain abscesses has increased to 50
percent. Earlier diagnosis and better antibiotic therapy
have improved the prognosis of these lesions.
Rousseaux and associates reported on a series of 12
patients who had multiple (two to six) intracranial ab-
scesses whose diameters ranged fro1n 0.5 to 5.0 c1n with
an average diameter 1.7 c1n (171). The causative organ-
ism was identified in only three cases. These patients
were treated vigorously with intravenous ampicillin, tri-
methoprimsulfamethoxazole, and sometimes with an
aminoglycoside such as gentamycin, sisomycin, or to-
bramycin administered intramuscularly. Treatment was
continued for about three months. The patients were
monitored for bone marrow depression, renal toxicity,
and cutaneous allergic phenomena. If needed, steroids
or mannitol treatments were given initially to combat
associated edema. Response to therapy was provided by
serial CT scans. In this scries, only two patients required
surgery, and both survived. One patient treated with anti-
biotics alone eventually died, giving a 10 percent 1nortal—
ity for the 10 persons treated without surgeiy.
During the three—year interval of their study, only two
instances of misdiagnosis by CT were 1nade. In both of
those cases, repeated CT scanning and lack of response
to treatment indicated that the multiple lesions were tu-
mors. Appropriate surgical therapy was then under-
taken.
Boom and Tuazon also have reported the successful
antibiotic treatment of seven patients harboring 2 to 10
brain abscesses each (172). Surgical treatment of these
lesions was not considered because of their multiplicity
and inaccessibility. A variety of antibiotics was used in
these cases: nafcillin, dicloxacillin, chloramphenicol,
penicillin G, PenV K, and rifampin. They used intrave-
nous antimicrobial treatment for about two months and
then continued oral therapy for several 1nore months.
The patients‘ progress was followed by means of CT
scanning.
These investigators concluded that high doses of anti-
biotics for an extended period may represent an altema—
tive approach in cases of multiple and inaccessible brain
abscesses. For this for1n of therapy to succeed, an early
response to antibiotics 1nust occur, and follow—up CT
scans 1nust be obtained. An early effort at making a1ni—
crobiological diagnosis is important to plan optimal anti-
biotic therapy; CT—guided needle aspiration may be the

key to diagnosis. Despite their success in this limited se-
ries, the authors reiterated the fact that surgical evacua-
tion of pus remains essential for most brain abscesses.
Subdural Abscess and Empyema
Subdural infection accounts for approximately 10 to
32 percent of all brain abscesses. The incidence of this
condition may be higher in developing countries
(3,17,63). Pus in the subdural space can be localized (ab-
scess) or diffuse (empyema). In approximately 50 per-
cent of cases, the subdural pus occurs as an empyema
spread widely over a hemisphere (Fig. 2). In the rernain—
ing half, the pus is loculated as a hemispheral convexity
mass (30 percent), in the interhemispheric fissure (10
percent), or in the posterior fossa (10 percent). Acute
frontal sinusitis and chronic mastoid infections are the
two most common antecedent causes. Chronic otitis1ne—
FIG. 2. CT scan showing right subdural empyema in a 64-
year—old woman admitted with sudden onset of generalized
seizures. She had low—grade fever and right hemiparesis, and
the peripheral white blood cell count was 19,700. With a ten-
tative diagnosis of chronic subdural hematoma, she was
taken to the operating room, and burr holes were made; there
was an unexpected free flow of grossly purulent material
from the subdural space. A craniotomy flap was then turned
for removal of a thick yellow membrane on the cortical sur-
face. Microbiological studies were negative. The patient was
placed on broad—spectrum antibiotics, and she recovered
after a prolonged hospital course. There was no antecedent
history suggesting the source of the infection, although she
had a history of chronic obstructive pulmonary disease and
an episode of bronchopneumonia one month prior to her ad-
mission. The subdural collection in this non—enhanced CT
scan covers much of the convexity of the right hemispheres
(arrows); the oortical markings on that side are diminished.
CNS INFECTIONS / 191
dia is particularly likely to be the underlying cause ofthe
empyema in developing countries such as India and Sn"
Lanka (173). The infecting bacteria may spread in a con-
tiguous fashion frorn the infected sinus or bone through
the adjacent dura and into the subdural space or may
spread from the infected sinus to emissary veins that
connect with subdural veins. A septic thrombosis for1n—
ing in a cortical vein creates a nidus of infection that
spreads in the subdural compartment in which the pus
can spread freely (123, 174, 175). Subdural empyema also
may occur as a consequence of trauma, cavernous sinus
thrombosis, scalp infection, or infected cephalohema—
torna. In addition, a preexisting subdural hematoma
may become infected as a result of concomitant sepsis or
iatrogenically from needle aspirations. Subdural ern—
pyeina was reported in 2 percent of patients following
the treatment of meningitis (176). Subdural empyema
may complicate a subdural—peritoneal shunt as in the
case of perforation of the bowel by the peritoneal end of
the shunt catheter (177). Another unusual source of sub-
dural infection is that associated with the pins penetrat-
ing the skull for halo immobilization of the neck (178).
Bacteriology
In a series of 66 patients with a subdural empyema,
aerobic or anaerobic streptococci were the infective
agents in 37 cases and staphylococci in six (179). Yoshi-
kawa, Chow, and Guze reviewed the bacteriological find-
ings of subdural empyemas and found that the most
common organisms were aerobic streptococci and staph-
ylococci (180). Salmonella is among the uncommon of-
fending organisms in subdural empyema; in children,
sahnonella infection of the CNS more commonly takes
the form of a subdural empyema, but in adults it is more
often found in the form of a brain abscess (181). Twelve
percent of cases were caused by anaerobic organisms,
and 27 percent of the cultures were "sterile." If "sterile"
cultures are assumed to be largely composed of inade-
quately cultured, anaerobic organisms, then about 40
percent of subdural infections may be caused by anaer-
obes. Khan and Griebel confirmed these bacteriological
findings (182). Posttraumatic and postoperative sub-
dural empyemas, however, were caused by S tapliylococ-
cus aareas or Staphylococcus epidermidis.
Clinical Manifestations
Subdural infection occurs more often in males. Local
infection in the region of the affected sinus, scalp, or
skull may be evident early, but infection within the sub-
dural space is heralded by intense generalized headache,
fever, drowsiness, meningeal signs, and focal neurologi-

192 / CHAPTER 10
cal findings such as J acksonian seizures, aphasia, or he-
miparesis. Interhemispheric pus often produces a contra-
lateral lower inonoparesis because it involves the medial
portion ofthe motor strip. Evidence of elevated intracra-
nial pressure (drowsiness, papilledeina, nausea, and vo1n—
iting) may also occur. Subdural empyema as a co1nplica—
tion of sinusitis may be misdiagnosed as aseptic
meningitis or viral encephalitis. Subdural infection is
usually less fulminant than bacterial meningitis but
more rapidly progressive than a brain abscess. In bacte-
rial meningitis, focal signs are less common, and preced-
ing sinus or mastoid infection need not be present. Clini-
cally, differentiating between subdural infection and
brain abscess may be difficult. Subdural abscess and
brain abscess may be present concomitantly but, for un-
known reasons, this is rare.
Laboratory Findings
Peripheral leukocytosis with a left shift is usual. The
erythrocyte sedimentation rate (ES R) is usually elevated.
In the series of Khan and Griebel, EEG was performed in
12 of 15 patients with subdural empyema, and in 10,
there was generalized or unilateral slow—wave activity or
unilateral voltage suppression (182). In a study of EEG
in the diagnosis of subdural empyema, the combination
of focal theta waves, unilateral depression of cortical ac-
tivity, and diffuse slowing of background activity has
been regarded as being characteristic for subdural e1n—
pyeina and may be more sensitive than CT scanning
(183). Early in the course of the disease, CSF findings
may be normal. Later, varying degrees of pleocytosis oc-
cur, the protein content increases, and the spinal fluid
glucose level remains near normal. The CSF remains
sterile unless there is an associated meningitis. Because
subdural empyema produces an intracranial mass, there
is risk that herniation and death may follow lumbar
puncture. Therefore, lumbar puncture should generally
be deferred in patients with meningitic symptoms and
focal neurological signs until subdural (or brain) abscess
has been excluded by CT or MRI scanning or angiogra—
phy (2,75,184).
Radiological Studies
Roentgenograms in patients with a subdural e1n—
pyeina often suggest sinus or mastoid infection. Osteo-
inyelitis may be seen about an involved sinus. If osteo-
inyelitis of the cranial vault is the underlying source of
subdural infection, it may be evident on skull films. In
view of the frequent association of subdural empyema
with paranasal sinus disease, plain x—rays of the skull and
sinuses should be obtained, especially because the initial
CT scan may be normal (185).
Danziger analyzed 11,300 CT scans in South Africa
and observed 23 (0.2 percent) cases of subdural e1n—
pyeina (6). On CT, a subdural empyema usually appears
as a cresenteric lesion at the periphery of the brain. En-
hancement may demonstrate a rim adjacent to the cor-
tex, and this rim may thicken with time. The ipsilateral
ventricle may be displaced. This rim may be thicker with
chronic processes. Cerebral edema is not a prominent
feature. CT scanning may fail to help in diagnosing sub-
dural empyema, presumably because, at some evolu-
tionary stage in its development, the combination of
brain and pus is isodense (60,186). A CT scan showing
unilateral subdural empyema is shown in Figure 2. The
incidence of false negative CT scans may be reduced by
routine use of contrast—enhanced CT in suspected cases
and, where feasible, the use of high—resolution scan-
ners (187).
MRI has been reported as being superior to CT in
identifying the presence and extent of subdural e1npye—
mas and in distinguishing empyema from chronic sub-
dural hematomas (188). Coronal MRI scanning may
demonstrate subtemporal extension of the empyema
(67). In some instances, RN scans may reveal the e1n—
pyeina (184,189) and cerebral angiography will also re-
veal the pus collection (190). In patients with subdural
collections complicating hemophilus influenza 1neningi—
tis, CT scanning is not reliable in distinguishing sterile
effusions from infected collections (e1npye1na) (191).
The accuracy of CT scanning is increased when coin-
bined with examination of Hemophilas inﬂaenzae cap-
sular antigen; this coinbination of diagnostic modalities
accurately predicts if the subdural collection is infected
or is likely to become infected (191).
In the past, ventriculography was used to diagnose pos-
terior fossa empyema; however, air studies are no longer
considered useful diagnostic modalities when high reso-
lution CT or MRI scanning is available.
Pathophysio logy
Several pathophysiological processes may be responsi-
ble for the rapid clinical deterioration seen in cases of
subdural empyema. Bacterial metabolic products or tox-
ins may adversely affect neural—glial function. BBB
breakdown may cause cerebral edema. Cortical vein
thrombosis may lead to associated cerebral hemisphere
infarction, and, finally, the mass of the subdural collec-
tion may lead to cerebral herniation (192).
Treatment
Subdural empyema represents a neurosurgical e1ner—
gency. Early drainage is essential because antibiotics

may not eradicate the infection. The rapid accumulation
of subdural pus can dangerously increase intracranial
pressure. Once the diagnosis is suspected, large doses of
broad—spectrurn antibiotics (such as a combination of
penicillin G, chloramphenicol, and nafcillin) should be
started, and the patient should be prepared for surgery.
Some surgeons drain the pus via multiple burr holes
placed over the involved area, but others prefer limited
craniectornies or even large craniotorny flaps to allow
wide exposure of the subdural infection. Bannister, Wil-
liams, and Smith recommend a wide craniotorny; of 66
patients in their series, 14 of 27 patients treated by burr
holes died, but only 5 of 35 died after craniotorny (179).
Several series have reported that later craniotorny was
needed for some patients initially treated by burr holes
(173,184). Areas of subdural abscess are copiously irri-
gated with such antibiotic solutions as bacitracin (or gen-
tarnycin). It is crucial that a specimen of the pus be ob-
tained for grarn—stain and culture for aerobic, anaerobic,
fungal, and mycobacterial organisms to aid in selection
of antibiotics.
When an interhemispheric subdural abscess is sus-
pected, the patient's head should be draped so that trephi—
nations or craniectomy can be performed parasagittally
from front to back and the entire interhemispheric re-
gion may be inspected, drained, and irrigated with antibi-
otic solution. Any undetected, undrained pus pockets
may lead to persistence of the intracranial infection. Pos-
terior fossa subdural empyema either is otogenic in ori-
gin or has spread from supratentorial subdural ern—
pyerna. The diagnosis may be delayed, even with the aid
of the new imaging techniques. Posterior fossa craniec-
tomy is recommended as the operation of choice, in pref-
erence to posterior fossa burr holes (193).
In the management of subdural fluid collection in in-
fant Hemophilus inﬂuenzas meningitis, Curless has re-
ported that subdural taps and systemic antibiotics are
usually effective (194). Another option is burr hole and
catheter drainage, along with antibiotic therapy (195).
Although the consensus among most authors favors ag-
gressive surgical evacuation of subdural intracranial ern—
pyernas, a minority viewpoint advocates treatment with
antibiotics and without surgery (196). The authors who
take the latter view emphasize the use of CT for diagno-
sis and follow up during the course of antibiotic treat-
ment.
The primary focus of infection leading to the subdural
suppuration also must be vigorously treated. When os-
teornyelitis of the frontal sinus is present, the infected
bone should be removed and the frontal sinus exenter—
ated. Ifthe skull and inner sinus wall appear intact, the
involved sinus should be drained. Surgery for sinus, rnid—
dle ear, or mastoid infection can be performed electively
(197), or it can be done simultaneously with the evacua-
tion of the subdural empyema.
CNS INFECTIONS / 193
Prognosis
Prior to the use of antibiotics, subdural empyemas
were usually lethal (197), but mortality has now declined
to 18 to 20 percent (198). As with brain abscesses, rnortal—
ity from subdural empyema increases with neurological
deterioration, and for the same reasons (182,184). Bilat-
eral spread of pus is a common cause of mortality. Early
diagnosis and bacteriological study for selection of
proper antibiotics are hkely to reduce the mortality. Sur-
vivors may be neurologically intact, but focal neurologi-
cal deficits, such as hemiparesis or dysphasia, are corn-
mon. Seizures occur in one—fourth to one—third of
survivors but may be controlled by anticonvulsant inedi-
cation (182). Calliauw, dePraetere, and Verbeke fol-
lowed 18 patients with subdural empyema more than
five years after successful surgical therapy (199). None
developed seizures after the second year following sur-
gery. Therefore, anticonvulsants should be given for ap-
proximately two years after successful treatment of a
subdural empyema. A similar experience was reported
by Cowie and Williams (192).
Intracranial Tuberculoma
Tuberculosis of the central nervous system may darn-
age the brain in many ways. A dense basal exudate may
form, which may obstruct CSF flow. Extension of this
basal exudate into the brain parenchyma itself may
cause a border—zone encephalitis. Multiple small foci of
ischemia may occur consequent to vasculitis involving
many small blood vessels. Infiltration of the meningeal
exudate into the walls of larger, basilar blood vessels may
cause brainstem infarcts. Intracranial tuberculomas may
form that act as both mass and inflammatory lesions
with accompanying edema. The pathological changes in
and around the reactive border zone of tuberculomas
has suggested a delayed type of hypersensitivity to tuber-
culoprotein, which is thought to initiate the "chain of
immunologic responses" (200). Occasionally, a more
acute form of brain edema develops with a diffuse, peri-
vascular loss of myelin as an allergic hypersensitivity re-
action to tuberculoprotein or to the brain's myelin basi
protein (201).
The incidence of focal tuberculous infection of the
brain—intracranial tuberculoma—varies according to
the prevalence of tuberculosis in the community. Al-
though intracranial tuberculosis is extremely common
in developing countries, epidemiologic data from devel-
oped countries are scarce: 89 tuberculomas were found
in 13,000 autopsies (0.68 percent) in Leeds, England
(1933) (202), whereas 43 were discovered during 15,000
postmortem exams (0.29 percent) in Los Angeles (1938)
(203). Thus, physicians in developed countries may fail

194 / CHAPTER 10
to recognize the disease because of its rarity. Tuberculo-
sis may be quite prevalent among immigrants from devel-
oping areas who co1ne to developed countries (204). Ac-
cording to reports fro1n countries where intracranial
tuberculomas are common, 32 to 50 percent of patients
with intracranial tuberculomas are younger than 10
years of age, and approximately 85 percent are younger
than 25 (201,205,206). Tuberculomas may occur any-
where in the brain, but infected children have a high
incidence of infratentorial lesions.
Pathology
Grossly, a mature tuberculoma is a well—defined, avas-
cular mass with multiple nodular extensions and a yel-
lowish, gritty, caseating central core. In its immature
form, the lesion consists of multiple small tubercles with
caseating or cystic centers surrounded by edematous
brain. More than half are adherent to the dura. Micro-
scopically, the central core of caseous necrosis is
surrounded by tuberculous granulation tissue consisting
of epithelioid cells, Langhans' giant cells, lymphocytes,
polymoiphonuclear cells, and plasma cells. Acid—fast ba-
cilli may be seen in either layer. The surrounding brain
shows degenerated nerve cells and ﬁbers, swollen astro-
cytes, and ohgodendroglia, as well as thrombosed vessels
and multiple microinfarcts. Rarely, frank tuberculous
abscess resembling a pyogenic abscess may occur
(207,208). Several cystic tuberculomas resembling g1io—
mas have also been observed (201,206).
Clinical Manifestations and Diagnosis (209,210)
Patients with intracranial tuberculomas usually have
evidence of the disease elsewhere or have had tuberculo-
sis. Fever of a few weeks‘ duration usually precedes the
onset of neurologic findings, which will vary according
to tuberculoma location. Seizures often occur with su-
pratentorial lesions. Children often have evidence of a
posterior fossa mass: headaches, nausea, vomiting, pa-
pilledema, nystagmus, ataxia, and separated cranial su-
tures or an enlarging head. Unusual presentations of tu-
berculomas include scalp swelling, a draining sinus, CSF
rhinorrhea, exophthalmos, trigeminal neuralgia, or evi-
dence of a pituitary or acoustic nerve "tumor" (201).
Intracranial tuberculomas can be diagnosed with a fair
degree of precision by CT, especially in geographic areas
where tuberculosis is endemic. The CT appearance of
intracranial tuberculomas has been classiﬁed as (1) small
discs and rings measuring less than 1 c1n in diameter
with marked contrast enhancement and surrounding
low—attenuation edema; (2) large rings lacking the low
central lucency of pyogenic abscesses (a central nidus—
,the so—called "target sign"—1nay be present); or (3) a
rlarge, ball—shaped nodular mass with irregular contours
(211). The lesions may be solitaiy or multiple. Although
CT scanning is the ideal diagnostic procedure, it may be
unavailable in developing nations where intracranial tu-
berculomas are iriost common (212). When CT or MRI
scanning is not available, plain skull x—rays, electroen-
cephalography, RN scans, angiography, and ventriculo—
graphy are still useful. In general, 2 to 6 percent of intra-
cranial tuberculomas calcify, but among Eskimos and
North American Indians, 60 percent of the lesions show
calcification (201).
Angiographically, a tuberculoma presents as an avas-
cular mass. Vessels in the vicinity may show a reduced
caliber, and the midline shift may be small relative to the
size of the lesion. Tuberculomas near the surface may
occasionally show a blush fro1n meningeal or cortical
vessels.
Treatment
Until the advent of CT scanning, surgical resection of
intracranial space—occupying lesions caused by tubercu-
lomas was the preferred treatment. Before the develop-
ment of effective antituberculous chemotherapy, surgi-
cal resection of these lesions carried a mortality of up to
85 percent fro1n subsequent tuberculous meningitis
(205). Total excision of the tuberculoma is preferred, but
partial excision may be done when large tuberculomas
impinge upon vital structures such as the brainstem
(205,206,213). In such cases, a rim of tuberculoma may
be left adjacent to the brain.
Following the development of effective drug therapy,
operative mortality for intracranial tuberculoma resec-
tion fell to about 14 percent, and the incidence of fatal,
postoperative tuberculous meningitis fell to 6 percent.
Although total excision of the lesion is preferred, partial
removal has been advised when large tuberculomas im-
pinge on vital structures (201,205,206,210). In such
cases, it is advisable to treat the residual lesion with anti-
tuberculous drugs. Various combinations of rifampin,
streptomycin, para—a1nino—salicylic acid, and isoniazid
are used pre— and postoperatively.
Paralleling the development of nonoperative treat-
ment for pyogenic brain abscesses, an initial nonopera-
tive approach for the treatment of intracranial tubercu-
lomas has emerged. This has been possible with the
advent of CT and MRI scanning for follow up. Antitu—
berculous drug therapy alone may be curative, especially
for small lesions. A therapeutic trial on antituberculous
medication is a reasonable approach. CT—guided biopsy
for histology and culture may be carried out for confir-
mation. Surgical resection may be required to reduce
intracranial pressure in the case of large lesions.
In 1983, Harder, Al—Kawi, and Carney reported on a
series of 20 patients with intracranial tuberculomas
(214). Ten patients were treated surgically, and 10 were
treated with antituberculous drugs alone. The progress

of the medically treated patients was followed serially by
CT scanning. No patients died in either group, but the
functional state of those treated medically was signifi-
cantly better than those who had surgery as their primary
therapy.
Tandon and Bhargava reported their experience with
50 patients with intracranial tuberculornas (211). In
these patients, neither vision nor life was threatened by
severe intracranial hypertension. All were treated pri-
marily with antituberculous medication, and serial CT
scans were obtained to follow their progress. The authors
divided their cases into three groups: (1) patients with
lesions larger than 1 cm; (2) those with multiple ring or
disc lesions less than 1 cm in diameter; and (3) patients
with solitary ring or disc lesions less than 1 cm in diarne—
ter. This study clearly showed that most intracranial tu-
berculornas resolve under medical management.
In conclusion, it seems that CT scan or CT scan plus
angiography can provide a high level of diagnostic confi-
dence with regard to intracranial tuberculornas. If intra-
cranial tuberculorna is suspected, intensive antitubercu-
lous therapy should be started and continued for two
weeks. Serial CT scans are obtained to follow the course
of treatment, which is continued for at least 12 months.
If the nature of the lesion is in doubt, either a therapeu-
tic trial of antituberculous drugs is initiated or biopsy
(stcrcotaxic or open) is obtained. If there is biopsy confir-
mation of tuberculoma, it is generally not necessary to
excise the lesion, and reliance is placed on antitubercu-
lous drugs to optimize long—ter1n neurological function.
Patients with large tuberculornas, with signs of raised
intracranial pressure threatening vision or life, may re-
quire surgical excision of the lesion before starting inedi-
cal treatment. However, if intracranial pressure is not
severely elevated, or if visual loss is not threatened, pa-
tients suspected of having intracranial tuberculornas can
be given a trial of medical therapy. Surgery can be re-
served for nonresponders. Papillederna without a serious
loss of vision is not considered a contraindication to ined-
ical treatment (215-217).
Steroids may be used when cerebral edema is severe
without fear of exacerbating the intracranial tubercu-
lorna. provided that antituberculous therapy is given con-
currently. Isoniazid, ethambutol, and rifampin in recom-
mended doses provide adequate coverage.
Intracranial tuberculous lesions may paradoxically
enlarge during antituberculous therapy, and resolution
of the tuberculous lesion demonstrated on CT may take
up to a year (218).
If CSF pathways are blocked, a shunt procedure may
be required (219).
Herpes Simplex Encephalitis (HSE)
Herpes is probably the most frequent cause of spo-
radic, viral infection with severe neurological sequelae in
CNS INFECTIONS / 195
temperate climates, including the United States (220-
223). The occurrence rate is believed to be about 2 cases
per million population per year (224). The virus infects
the nasal mucosa and nasopharynx and penetrates the
CNS through the cribiforrn plate (225). Pathologically,
perivascular lymphocytic infiltration is seen, along with
severe necrosis of the medial temporal and orbital fron-
tal lobes. Other areas in the brain are less often involved
(226). Type A Cowdry eosinophilic inclusions are seen
in both neurons and glia (227). Electron microscopy
demonstrates herpes virus particles within affected cells
(220). Often, severe temporal lobe swelling accompanies
the infection and may cause a significant intracranial
mass lesion that may have to be removed surgically.
Clinical Manifestations and Diagnosis
Clinically, HSE is manifested by headache, drowsi-
ness, fever, seizures, and focal neurological signs. Men-
ingeal signs are not prominent. These nonspecific find-
ings may be seen with many types of encephalitis, but
herpes infection is characterized by prominent psycho-
logical symptoms early in the disease (global confusion,
disorientation. clouding of consciousness, and hallucina-
tions, particularly olfactory and gustatory), because of
temporal lobe involvement (227). Early diagnosis of
herpes is vital because, untreated, the disease has a high
mortality and may be associated with severe neurologi-
cal sequelae in survivors. EEG usually shows temporal
high—voltage sharp waves. RN scanning is characterized
by unilateral or bilateral areas of hyperperfusion with
focal uptake on the static images. When bilateral, this
strongly suggests HSE (60). After the disease is estab-
lished, CT scans reveal a low—density area, usually in the
medial temporal lobe, unilaterally or bilaterally. There is
an irregular pattern of contrast enhancement. These
three neurodiagnostic modalities are positive in about 80
percent of cases (228). MRI scanning is more sensitive
than CT in detecting early changes. Petechial hemor-
rhages, in particular, which are commonly seen patholog-
ically in HSE, may not be detected on CT scanning, but
they are readily seen on MRI scanning, thereby i1nprov—
ing diagnostic specificity (67). Failures probably relate to
the stages of the disease at which the tests are performed.
Fluorescent antibodies of the herpes virus antigen and a
passive hernagglutinating antibody may be dernon—
strated in the cerebrospinal fluid.
Treatment
In the late 1970s, mortality of biopsy—proven HSE was
shown to be more than 70 percent (229), and neurologi-
cal sequelae were noted to be severe among survivors
(229-232). Adenine arabinoside (Ara—A, vidarabine) was

196 / CHAPTER 10
found to be a fairly effective antiviral agent for the treat-
ment of HSE, reducing mortality to about 47 percent
(232). After the original report of Whitley and associates
showed the efficacy of vidarabine (232), a subsequent
study raised questions about the usefulness of this drug
(233). However, further uncontrolled studies by Whit-
ley's group supported vidarabine (228,234), though the
mortality of HSE still approximated 50 percent with the
use of the drug.
In 1984, Skoldenberg and colleagues studied 51 pa-
tients with HSE to compare the effectiveness of vidara-
bine with acyclovir, a purine nucleoside analogue (224).
Acyclovir appeared distinctly more effective than vidar-
abine, but factors such as level of consciousness, age of
patient, and absence of brain biopsies to prove abso-
lutely that each patient had HSE could have affected the
results. A subsequent study was therefore undertaken by
Whitley and colleagues to compare acyclovir efficacy
with vidarabine (228). Their results indicated the superi-
ority of acyclovir in terms of mortality. Survival was
found to be influenced by patient age, level of conscious-
ness; and duration of disease before the start of therapy.
Even with statistical adjustments to account for these
factors, however, acyclovir was seen to be the superior
drug for reducing HSE mortality.
With both drugs, survival and return to normal func-
tion have been positively correlated with adequacy of
neurological function. Acyclovir treatment must be
started as soon as possible when HSE is suspected. Whit-
ley's group, in particular, believes that brain biopsy is
mandatory to confirm the diagnosis (232). The biopsy
can be carried out with CT guidance (235). Brain biopsy
may reveal conditions other than HSE, such as tubercu-
lous and cryptococcal meningitis or subdural ernpyerna.
The risk to the operating team in obtaining a biopsy in
such patients is thought to be minimal (236). Biopsy is
also recommended in infants and children with sus-
pected herpes simplex virus encephalitis (237). If one
suspects HSE. acyclovir should be started before brain
biopsy is obtained. Side effects from acyclovir have, thus
far, been minimal, so the drug may be safely continued
while awaiting HSE viral cultures. If the herpes virus is
isolated, drug therapy is continued for 10 days. Because
acyclovir is nontoxic, one may make a cogent argument
for continuing the drug a full 10 days in the face of nega-
tive HSE viral cultures because brain biopsy may miss
the herpes focus 25 percent of the time (225).
Despite the safety of antiviral drug therapy, brain
biopsy has been recommended in patients with possible
HSE (238). These authors state that the rationale is not
to confirm HSE but rather to rule out other treatable
conditions. Such conditions may be suspected in pa-
tients with low CSF glucose, raising suspicion of infec-
tions such as tuberculosis, brain abscess, toxoplasrnosis,
or cryptococcosis.
Parasitic Brain Abscess
Cysticercosis
Life cycle
Humans are the definitive host for the pork tape-
worm, Taenia solium. The adult form of the tapeworm
lives in the human small intestine. The pig itselfbecomes
infected with the parasite by eating ova or gravid worm
segments from human excretia. Once the pig ingests the
ova, the surrounding capsule is digested away and the
contained larvae penetrate the pig's stomach mucosa
and are disseminated widely in the animal's body. Hu-
mans, after ingesting infested pork, develop a mature
tapeworm in the small intestine. Humans can harbor not
only the mature tapeworm but also the larval form. Vorn—
iting or reverse peristalsis delivers proglottids from the
small intestine to the stomach (239-241). In humans,
once the larvae penetrate the gastric mucosa, dissenrina—
tion to the brain is the rule.
Despite these presumed mechanisms of infection,
much is unknown about the transmission of the disease.
Relative to the probability of fecal—oral contamination,
simultaneous infestation with both the adult and larval
forms of the parasite is uncommon in those with cysti-
cercosis. Cysticercosis is prevalent in countries where
uncooked pork is eaten, but the disease is also endemic
in India where eating uncooked or raw pork is very
rare (241).
Incidence
This parasitic infestation is relatively common in eco-
nomically developing areas such as Mexico, Central and
South America, Africa, and India. Although it is tradi-
tionally rare in developed countries (242), an increasing
incidence ofthe infestation in children has been reported
in the United States (243) and in Australia (244), related
to immigrant populations and travelers from endemic
areas. The migration of Mexican and Central American
people into southern and southwestern states in the
United States has made Cysticercosis a more common
diagnostic consideration in cities such as Los An-
geles (245).
In Mexico and many Central and South American
countries, 2 to 5 percent of all pigs slaughtered have evi-
dence of cysticercosis. Among all autopsies performed at
the General Hospital in Mexico City, 3.6 percent had
evidence of Cysticercosis, while at the Federal University
of Parana, Brazil, 2.2 percent of 7567 brain CT scans
showed evidence of Cysticercosis. Cerebral Cysticercosis

recently accounted for 13 to 33 percent of all space—occu—
pying intracranial lesions at the Mexico City General
Hospital (241). By contrast Couryille, from the United
States, found only 22 cases of cysticercosis among 3000
verified brain tumors (246).
Pathology
Pathologically, the disease may result in (l) rnenin—
goencephalitis; (2) granulornatous meningitis; (3) focal
granulomas (aseptic abscess); (4) focal cysts; (5) hydro-
cephalus (cornrnunicating or obstructive); (6) ependyrni—
tis; or (7) arteritis (241,247). Living cysts within the brain
incite little or no nearby tissue reaction, and infested
patients may be asymptomatic. When the organisms
within the cysts die (after 18 months or so), they cause an
intense inflammatory reaction around the cyst. Patients
often become symptomatic during this stage, with sei-
zures and focal findings. Finally, dead cysts are reab-
sorbed and calcification of the lesion occurs; heterotopic
bone formation has also been described, presumably sec-
ondary to new bone formation around muscle cysticerci
(248). The parasite also may exist in a racemose form
about the base of the brain. Some evidence suggests that
intraparenchymal brain cysts form if spread to the cen-
tral nervous system occurs via the carotid artery,
whereas the racemose form appears when cerebral
spread has occurred via the vertebral artery.
Clinical Manifestations and Diagnosis
Clinical syrnptornatology depends upon the number
of cysts, their size, location, and the toxic quality of the
parasite. The clinical course of the disease is character-
ized by remissions and recurrences. Intracranial cysts
produce five basic clinical disorders: (1) convulsions; (2)
"pseudotumors" from diffuse parenchymal involve-
ment with raised intracranial pressure and small ventri-
cles; (3) intracranial space—occupying lesions (cerebral
cysticercosis with focal symptoms); (4) rneningoence—
phalitis; and (5) psychiatric disturbances (241). lntraven-
tricular cysts occur in 15 to 20 percent of patients with
neurocysticercosis. Possibly the larval oncospheres reach
the ventricles via the choroid plexus. lntraventricular
cysts may lead to positional headaches, rapid deteriora-
tion of level of consciousness, and death from acute ob-
struction of CSF flow. Obstruction of CSF flow by the
racemose basal form of the disease is usually more
chronic and less catastrophic than obstruction of flow
caused by an intraventricular cyst that happens to block
the intracerebral CSF pathway (249). If the associated
basal leptorneningitis is severe and extends to involve the
CNS lNFECTl0NS / 197
cord, amyotrophy and spastic paresis can also occur. Re-
mote cysts about the chiasrn may cause blindness (250).
Plain roentgenograrns ofthe skull may reveal evidence
of increased intracranial pressure or intracranial calcifi-
cations. However, CT and MRI scanning are the best
diagnostic modalities. CT scanning is accurate (25 l) and
is particularly useful in detecting parenchymal calcifica-
tions within dead larvae (252). CT can detect intraparen-
chymatous calcifications and cysts, intraventricular
cysts (with the aid of inj ected contrast media), and hydro-
cephalus (253). Cysticercosal calciﬁcations, several rnil—
lirneters in diameter and scattered through the brain par-
enchyma, occur in about 65 percent of patients (254).
Calcifications are more common in adults, whereas dif-
fuse homogeneously enhancing lesions are more often
seen in children (255). Cysts occur about 25 percent of
the time, and these may occur within brain parenchyma
or within the ventricles (25 4). Over 40 percent will show
hydrocephalus by CT, but scanning may not delineate its
cause because the intraventricular or subarachnoid para-
sitic cysts are of CSF density. Furthermore, racemose
organisms at the base of the brain will not be delineated
by CT scanning. lntraventricular contrast may outline
intraventricular cysts, which may change in position
(255). CT scans of the acute parenchymatous form of
cysticercosis may reveal (l) diffuse low—density areas
within the white matter, which enhance with contrast
plus compressed but undisplaced ventricles: (2) multiple
small low—density areas with discrete rounded central en-
hancement; or (3) large cystic lesions that "ring en-
hance." Multiple cystic lesions occur about 85 percent of
the time, but the lesions are solitary in 15 percent of the
cases (256).
The advent ofCT scanning has enabled investigators
to follow the natural evolution of intracranial cysticerco-
sis, and intraparenchymal cysts have been observed to
disappear spontaneously and be replaced by small areas
of calcification (257). Thus, it appears that neural cysti-
cercosis may be well tolerated by some individuals. Spon-
taneous cyst disappearance makes it somewhat difficult
to evaluate drug treatment that also may cause cyst invo-
lution. Contrast enhancement seen about intraventricu-
lar cysts indicates the presence of a granular ependyrnitis
with adhesions between the cyst wall and ependyrna
(255). When this phenomenon is seen, owing to ependy—
rnal inflammation, CSF shunting may be necessary even
if the cyst is successfully excised. Before the availability
of CT scanning, Skromme—Kadlubik, Celis, and Ferez
tagged anticyst antibodies to Indiurn—ll3. Intracranial
Cysticercosal cysts selectively concentrated this isotope
and presented increased activity on radioisotope
scans (258).
MRI scanning, especially with the use of intravenous
contrast material, is also highly accurate in locahzing
lesions of cerebral cysticercosis (259). Tl—weighted

198 / CHAPTER 10
images are effective in early detection of intraventricular
lesions (252).
A peripheral blood smear may show eosinophilia. Spi-
nal fluid glucose is usually low, but protein is often ele-
vated; CSF eosinophilia occurs in about 20 percent of
patients. Indirect hemagglutination tests against cysti-
cercosal antigen may be positive in blood or CSF. CSF
complement fixation tests against the parasite generally
yield positive results, but the assay can be difficult to
perform because no standardized antigens or assay tech-
niques exist. Cysticercosal antigens cross—reacting with
echinococcus or schistosomiasis may also be a problem
(260-262). Other tests that have been used to detect cys-
ticercosis include agar gel precipitation, immunoelectro—
phoresis, counter electrophoresis, indirect irnrnunoﬂuo—
rescence, blastoid transformation, and skin reaction,
each with variable rates of success (241).
Treatment
Praziquantel is an antihelminthic that is quite effec-
tive against cysticercosis. Sotelo and associates studied
26 patients treated with this drug (263). After three
months all patients had improved clinically, and 50 per-
cent were asymptomatic. The drug is tolerated quite
well (264).
Patients receiving praziquantel exhibit side effects ow-
ing to the brain's inﬂammatory reaction to dying and
dead parasites. To combat this reaction, some authors
have recommended concomitant steroid adrninistra—
tion. Ciferri compiled four large series of patients with
neurocysticercosis treated with praziquantel (265). Only
11 to 16 percent of patients who received steroids along
with praziquantel exhibited adverse reactions, whereas
92 to 100 percent of patients receiving praziquantel
alone had adverse reactions from dying parasites. De-
Ghetaldi, Norman, and Douville concluded that prazi-
quantel alone is a remarkably safe drug when adrninis—
tered to healthy volunteers but that it becomes
increasingly hazardous in patients with severe neurocys-
ticercosis (266). These investigators believed that ste-
roids should be given along with praziquantel; the bene-
fits of administering steroids for one to two months to
suppress the brain's reaction to dying and dead organ-
isms far outweighed the risks of potential, steroid—in—
duced side effects.
The efficacy of praziquantel may radically alter the
indications for surgery in neurocysticercosis. In the past,
it was pointed out that up to 90 percent of patients with
CT—demonstrated hemisphere lesions had a nonprogres—
sive course not requiring surgery (267) and that patients
presenting with epilepsy as the only clinical rnanifesta—
tion were often successfully treated with standard anti-
epileptic drugs alone (241). One may sunnise that pa-
tients presenting with a "pseudotumor" syndrome from
miliary cysts, edema, and small ventricles can be success-
fully treated with praziquantel and steroids.
Should surgery become necessary, the best operative
results (75 percent improvement, 24 percent mortality)
have been obtained with excision of cysticerci, which
form a single, discrete, space—occupying lesion within the
brain and produce focal signs. The poorest results (28
percent improvement, 67 percent mortality) have been
seen in patients who developed basal leptomeningeal in-
fection (268). Sorne authors recommend surgical exci-
sion of cysticercosis cysts when they produce focal syrnp—
toms and are surgically accessible (269). In a series of 141
patients with neurocysticercosis, over 50 percent were
cured following praziquantel treatment; intraventricular
cysts were unaffected by the drug and had to be surgi-
cally removed (270). Intraoperative ultrasound (neuro-
sonography) is helpful in detecting subcortical lesions
(271). Many who are experienced with cysticercosis cere-
bri advocate leaving basal cysts in situ. They prefer to
deal with the problem of CSF obstruction by communi-
cating the temporal horn with the cisterna ambiens or
using a standard CSF shunt. Spread of the organisms by
shunting the CSF is unlikely because cysticercosis cysts
are rarely found in the lateral ventricles. Intraventricular
cysts are potentially dangerous because they may ini-
grate, plug CSF circulation pathways within the brain,
and lead to acute hydrocephalus and abrupt death. They
may be removed stereotaxically or by a direct surgical
approach (245). If the cyst is unruptured or has not in-
cited a granular ependymal reaction (determined by en-
hancement of the cyst on preoperative CT scans), simple
cyst removal may sufﬁce. Sometimes, CSF shunts are
required even after successful cyst removal if tissue reac-
tion to the parasite obliterates CSF pathways (245,267).
Occasionally, patients with acute obstructive hydroceph-
alus will require shunting before cyst removal in order to
reduce intracranial pressure (249).
Echinococcosis Granulosus
Life Cycle and Incidence
Hydatid disease in humans is caused by the larval
stage of the tapeworm Echinococcus granulosus. The
mature worm lives in the intestine of the dog. Ova passed
in dogs‘ feces infect grass eaten by sheep, in whose lungs,
liver, or other abdominal organs the ova develop into
encysted embryos. If dogs eat the offal of infected sheep,
the parasite matures in the dogs‘ intestine and its life
cycle is repeated. Human infection arises by contamina-
tion of food by dust containing viable ova or by oral
contamination from the hands after handling infected
dogs. Only about 2 percent of those who develop echino-
coccal disease have central nervous system involvement
(272). Nevertheless, hydatid cysts account for about 2 to

3 percent of intracranial space—occupying lesions in An-
kara, Turkey (273). Children are affected 2.5 times more
frequently than adults. In countries where hydatidosis is
common, up to 50% of childhood tumors of the CNS
turned out to be hydatid cysts.
Pathology
The disease exists in two forms. Intracranially, the dis-
crete and encapsulated hydatid cyst acts as a space—occu—
pying lesion. Because cerebral hydatid cysts are fre-
quently single, surgical therapy is often successful. Most
cysts start in the subcortical area and spread deeper into
the white matter. The cerebral hemispheres are more of-
ten infected than the cerebellum. Intraventricular and
even intrasellar cysts have been reported (274,275). The
unencapsulated parasite may invade the bone of the cra-
n1u1n.
Clinical Manifestations and Diagnosis
In children, the peak incidence occurs between ages 5
and 10. Affected children may have raised intracranial
pressure, diminished visual acuity, mental changes, ho-
rnonyrnous field cuts, and hemiparesis. Characteristi-
cally, however, one is confronted with a child in good
general health who lives in an endemic rural area and has
elevated intracranial pressure without focal findings
(276). In the adult, the clinical picture is less well de-
fined. Increased intracranial pressure is usually evident,
but the differentiation between echinococcal cysts and
tumors may be difficult.
Plain x—rays of the skull in the child may show suture
separation or thinning of the cranial vault, whereas RN
scans reveal absence ofuptake at the cyst site. If angiogra—
phy is done, it may reveal significant vascular displace-
ment by an avascular mass. CT scanning reveals a cyst,
often with nonspecific mass effect (277). Calcification of
the cyst wall may occur, and its presence raises suspicion
of echinococcosis cyst. Rarely, there is a fine enhancing
rim. The cyst may occur in various sites, including the
aqueduct of Sylvius (278) and the skull.
Treatment
In the presence of increased intracranial pressure, the
cyst fluid may be aspirated by puncture via a burr hole
and may be followed by systemic antihelminthic treat-
ment with rnebendazole (279) or albendazole (280). Sur-
gical excision of the encapsulated cyst may be necessaiy
(Fig. 3). The removal can be done by cortical incision,
exposure of the cyst, and gentle irrigation between cyst
wall and brain. Ozgen and colleagues reported 11 succes-
sive cures with surgery (281).
CNS INFECTIONS l99
FIG. 3. Hydatid cysts removed at surgery, unruptured. The
outer laminated membrane has been opened, revealing so-
called brood capsules contained within. (Courtesy of Dr.
George Craven, Department of Neurosurgery, Louisiana
State University Medical Center.)
Cranial hydatid disease also represents an unencapsu-
lated form of the parasite that occurs in either the cranial
base or vault. It may result in increased intracranial pres-
sure, focal neurological disturbances, skull deformity,
and cranial nerve palsies. Involved bone of the vault may
be widely resected, but this may not be possible with a
basal lesion.
Schistosomiasis
Infestation by the trernatode worm Scliistosoma af-
fects an estimated 200 million people worldwide (282).
Acute cerebral schistosomiasis can cause a fulrninating
encephalitis, whereas the chronic form of the disease
produces intracranial granulomas with obstruction to ce-
rebrospinal fluid flow, elevated intracranial pressure.
and locahzing signs. Unfortunately, there are no speciﬁc
clinical features that are pathognoinonic of the disease.
Schistosomicidal chemotherapy supplemented with cor-
ticosteriods is usually effective (283).
Toxoplasmosis
Toxoplasmosis gondii. an obligate intracellular proto-
zoan, causes one of the commonest infections in Arner—
ica; from 20 to 70 percent of adults in the United States
demonstrate Toxoplasina antibodies. In i1nrnunoco1n—
promised individuals, protozoa invade and destroy cells

200 / CHAPTER 10
producing necrotic regions surrounded by an intense
rnononuclear reaction. Patients may become i1n1nuno—
compromised secondary to AIDS, secondary to treat-
ment for rnahgnancies, or following organ transplanta-
tion (284—287). In the CNS, T. gondii infections can be
classified into one of three patterns: (1) diffuse encepha-
lopathy with or without seizures; (2) meningoencephali-
tis; or (3) single or multiple progressive mass lesions. The
T. gondii trophozoites may be identified by Gie1nsa—
stained preparations of abscess aspirate. Inoculations of
purulent material into mice and fluorescent antibody
techniques also may lead to definite identification of
Toxoplasrna organisms. Pyrimethamine and sulfadia—
zine (or triple sulfonamides) are the current drugs of
choice, and prompt initiation of therapy provides a more
favorable outcome. Naturally, ultimate prognosis de-
pends on the severity of brain involvement plus the
seriousness of the underlying disease. If one is dealing
with an immunocompromised patient and the CT scan
suggests toxoplasrnosis, empirical medical treatment
may begin and the patient is followed by serial CT scans.
If the lesions clear, this presumes T. gondii infection, and
brain biopsy may be avoided.
Paragonimiasis (288)
Paragonimiasis is a parasitic infection caused by the
lung fluke Paragonimus westermani and related species.
The infection is prevalent in the Far East, Southeast
Asia, some parts of Africa, and South America. In one
endemic area, 24 percent of space—occupying lesions
within the brain were caused by Paragonimus. It is
caused by the ingestion of inadequately cooked crusta-
ceae contaminated with the larval form Paragonimus,
which migrate from the duodenum to the lungs. Most
investigators believe that immature or mature worms
follow vascular structures from the chest to the head and
enter the brain via foramina at the base of the skull.
Entrance through the jugular foramen is highly suspect
because most cerebral lesions are posterior, particularly
in the occipital, parietal, and temporal lobes. Cerebral
paragonimiasis may present as an acute meningoence—
phalitis, a well—encapsulated granuloma, or a chronic
calciﬁed lesion. Seizures, headache, visual disturbances,
and hemiparesis are the most common symptoms and
signs. Plain x—rays of the skull may reveal posterior calci-
fications. CT scanning reveals ring—like or nodular en-
hancing rnasses in the early stages (289,290). Shell—like
calcified clusters occur in the chronic form (291). Cere-
brospinal fluid may be normal or abnormal. Occasion-
ally, Paragonimus ova may be seen in the CSF. Cornple—
rnent—fixation tests of cerebrospinal fluid against
Paragonimus antigen are positive in 40 to 80 percent of
cases of cerebral infestation. The parasite may also in-
volve the spinal cord. The worms probably migrate into
the spinal epidural space directly from the lungs, because
an extradural thoracic location is most common.
Although medical therapy with praziquantel provides
primary treatment, surgery may be performed for intra-
cranial mass lesions that cause increased intracranial
pressure. Small cysts may be entirely enucleated. The
contents of large cysts are evacuated, but the walls are
left behind.
Entamoeba Hlstolytica
Brain abscesses caused by Entamoeba histolytica
(292-295) usually have a hematogenous origin from E.
histolytica abscesses of the lung or liver, although at least
five cases of direct spread of this organism from bowel to
brain have been reported. From 0.7 to 8 percent of he-
patic amebiasis will have associated brain involvement.
E. histolytica brain abscesses are usually solitaiy and un-
encapsulated. The abscess progresses rapidly and fre-
quently ends fatally, but several instances have been re-
corded of survival following aspiration and antiamebic
drug therapy.
Trypanosomiasis
A studyTias suggested that subcurative treatment of
systemic trypanosomiasis may permit the parasite to
enter the brain and to cause meningoencephalitis (296).
Poisson and associates reported the occurrence ofpseu—
doturnors associated with Trypanosoma gambiense
(297). Clinical signs included progressive hemiplegia and
papilledema, although the hemiplegic form has been re-
ported as unusual (298). CT scans demonstrated asy1n—
metric al hypodense areas in the white matter, and arteri-
ography showed vascular displacement. Serial CT
scanning revealed associated cerebral edema and demye—
hnation. Arsenicals plus corticosteroid treatment led to a
rapid clinical improvement in their patient. The differ-
ential diagnosis includes tuberculosis, syphilis, and fun-
gal infection (298).
Fungal Brain Abscess
Fungal infections of the central nervous system occur
spniw ng ml persons. More commonly,
however, such infections are found in debilitated, dia-
betic, or immunocompromised individuals. Recipients
of organ transplants, patients with lymphomas, acute
leukemia or aplastic anemia, and those on cytotoxic che-
motherapy are also susceptible, as are those with abnor-
mal irnrnunoglobulins (299,300). Because of the altered
immune response, the host is often unable to confine a
fungal brain abscess, and CT scans in such cases often
show poorly circumscribed, low—density lesions with lit-

tie contrast enhancement. These CT characteristics in
patients with fungal brain abscesses are often associated
with a poor prognosis (301). Mortality following fungal
brain infection is high, not only because of the brain
infection itself, but also because of the underlying dis-
ease.
In one neurosurgical series of 78 patients with fungal
infections of the CNS, Coccidioides immitis and Crypto-
coccus neoformans accounted for two—thirds of the in-
fections; 15 percent were associated with intracranial
mass (302).
Coccidioidotnycosis (303,304)
Coccidioidornycosis is caused by a fungus that exists
in the mycelial form in hot desert soils and occurs as
spherules in the human host. Brain infection usually oc-
curs as a meningitis that is generally fatal. Hydrocepha-
lus and increased intracranial pressure occur because of
obstruction to CSF flow. Shunts are usually required for
control of CSF. Until recently, amphotericin B was the
only effective treatment, and it was given either by re-
peated lurnbar injections or via a bubble reservoir placed
under the scalp and connected to a lateral ventricle by a
silicone tube (Ommaya reservoir). Amphotericin B is
toxic in itself, and its administration has resulted in sig-
nificant morbidity. The imidazole antifungal agents, mi-
conidazole and ketoconazole, may be effective with less
morbidity than amphotericin B. Miconidazole is given
intraventricularly with an Ommaya reservoir, and keta—
conazole is taken orally.
Cryptococcosis (305,306)
CNS cryptococcal infection occurs in persons exposed
to pigeon and chicken droppings and appears particu-
larly in debilitated, immunocompromised patients. The
organism Cryptococcus neoformans reaches the brain or
spinal cord by way of the blood and usually produces a
meningitis, although space—occupying lesions that re-
quire excision have been reported. Currently, 60 percent
of cryptococcosis patients who receive amphotericin B
are cured. Addition of 5—fluorocytosine may be useful,
but this is not well established.
Aspergillosis (301,307—315)
Aspergillosis is caused by a fungus of the genus Asper-
gillus. The infection can involve the meninges, paren-
chyma, or blood vessels. A. fumigatus is the most corn-
mon species causing disease in man. Usually the
organism enters the CNS by hematogenous spread from
lung or intestine, but occasionally direct penetration oc-
curs frorn an involved sinus or orbit. Although CNS
CNS INFECTIONS 201
aspergillosis can occur in otherwise healthy persons, the
disease is often associated with drug addiction. AIDS.
diabetes mellitus, carcinomatosis, immunosuppression.
and other debilitating disorders. Generalized aspergillo-
sis spreads to the CNS about 1 8 to 50 percent of tl1e time,
In the CNS, lesions can be either acute
purulent) or chronic (granulomatous). Fungal aneritis
may be caused by extension of the fungus into the nails
of cerebral arteries, and this may result in cerebral infarc-
tion or hemorrhage. In one series of nine fungal brain
abscesses among immunocompromised persons, eight
were caused by aspergillosis. The clinical findings de-
pend upon the site and extent of the lesion. CT scans;
delineate the extent of neuraxis involvement but are not
specific for aspergillosis. Spinal aspergillosis has been re-
ported in normal individuals, in the irnrnunocorn—
promised, and in patients who have had lumbar disc
surgery. Although intraventricular and systemic ampho-
tericin B (perhaps in combination with rifampin) can be
effective in some cases, the ultimate prognosis is usually
guarded because of the underlying systemic disease.
North American Blastomycosis (3 16-322)
Blastomycosis is a fungal disease caused by Blasto-
myces dermatitidis. a soil saprophyte common in the
central part of the United States. The portal of entry into
the body is the lung. Pulmonary blastomycolic lesions
may be confused with tuberculosis. Meningitis is the
most common form of CNS blastomycosis, but solitary
mass lesions in the brain occasionally occur. Clinically.
patients may present with headache, coma, confusion.
memory loss, aphasia, paresis, increased intracranial
pressure, or signs of meningitis. Diagnosis is difficult un-
less blastomycosis is present elsewhere. Skin testing has
limited value, because the blastomycosis antigen cross-
reacts with Histoplasma and Coccidioides. White blood
cell count and erythrocyte sedimentation rates are gener-
ally normal. CT scanning reveals an isodense or slightly
hyperdense solitary mass with contrast enhancement
and surrounding edema. The scan appearance may be
suspicious for tumor. Definitive diagnosis is based on
biopsy, culture, or/both. Amphotericin B may be cura-
tive, but surgicalremoVal of the intracranial lesion may
be r e q u i r e d .
Phycomycosis (Mucormycosis) (323-326)
Cerebral mucormycosis is an acute, rarely curable
fungal disease that affects the nasal sinuses, orbit, and
brain. The fungus usually becomes pathogenic for hu-
mans, in association with predisposing debilitating con-
ditions, such as diabetic acidosis, and altered immune
conditions, including use of antibiotics or corticoste-
roids. Cerebral rnucorrnycosis, however, has been re-

202 / CHAPTER 10
ported following open brain injury alone. Patients with
mucorrnycosis often have proptosis, orbital cellulitis,
and total ophthalmoplegia. Central nervous system in-
vasion (acute meningoenccphalitis and purulent 1nenin—
gitis) occurs along arteries that transverse the lamina cri-
brosa. The fungus has a predilection for arterial
invasion, which can lead to thrombosis and cerebral in-
farction, hemorrhage, or dissecting aneurysms.
Paranasal sinus involvement appears as rnucosal
thickening on CT scans. Bone destruction is occasionally
seen. CT scan evidence of intracranial involvement is
shown by presence of abscess or infarction. The fungal
abscess appears as a low—density mass with variable pe-
ripheral enhancement and little surrounding vasogenic
edema.
Treatment includes control of the underlying cause,
local drainage, or debridement of the involved tissue and
use of amphotericin B. both systemically and via local
irrigation. Hyperbaric oxygen has been used for treat-
ment of the disease by providing increased oxygen perfu-
sion of tissues distal to occluded arteries. Hyperbaric ox-
ygen may reduce local acidosis and thereby inhibit the
growth rate of fungus.
Histoplasmosis (327)
Histoplasmosis is caused by the dimorphic fungus,
Histoplasma capsulalum, which rarely infects the cen-
tral nervous system. When the CNS is infected, rneningi—
tis usually results, but occasionally parenchymal granu-
loinas occur. Amphotericin B is used for treatment.
Candidiasis (328-330)
Candidiasis is usually a chronic infection caused by
various species of the imperfect fungus, Candida. Cen-
tral nervous system infection usually follows systemic
disease in debilitated persons with diabetes, malignan-
cies, or immunologic problems in those treated with anti-
biotics, steroids, or immunosuppressive drugs. The usual
infection is meningitis, but parenchymal involvement
may occur. In infants, Candida brain abscess may occur
in association with gastrointestinal lesions, postopera-
tively, or following treatment with antibiotics. Candida
discitis following bowel surgery in an adult has been re-
ported. Amphotericin B and 5—fluorocytosine are effec-
tive drugs, but the ultimate prognosis is often poor be-
cause of the underlying disease.
Neurological Sequelae of Amphotericin (331)
Intrathecal administration of amphotericin B may
cause transient or permanent spinal cord dysfunction
(myelopathy). Pathological studies following amphoteri-
cin myelopathy in one patient disclosed no evidence of
arachnoiditis, suggesting that the dysfunction results
from a vascular abnormality (i.e., possible transient
spasm).
If a patient receiving amphotericin B experiences tran-
sient spinal cord symptoms, the amount of drug given
intrathecally may be reduced and the injections sched-
uled farther apart. Alternatively, the drug may be given
intraventricularly by means of a reservoir unit. Consider-
ation may be given to changing medication, but when
amphotericin B is essential, this may prove difficult. Mi-
conazole may become an alternative to amphotericin B.
Acquired Immunodeficiency Syndrome (AIDS)
Acquired immunodeficiency syndrome (AIDS) and
AIDS—related complex (ARC) have been shown to be
caused by the human immunodeficiency virus, HIV. As
a result of the immune deficiency, the body is subject to a
wide spectrum of opportunistic infections and rnalig—
nant tumors. In addition, there is increasing evidence
that the human immunodeficiency viius type 1 (HIV-1)
is neurotropic and that it can invade the brain directly,
although its pathogenesis is not well understood
(332,333).
Because the mortality of AIDS is 100 percent, a large
literature concerning its protean pathological rnanifesta—
tions has emerged. The nervous system is significantly
involved in the majority (at least 74 percent) of cases
(334-336). A predominant feature is opportunistic in-
fections (cryptococcal infection, toxoplasmosis, cyto1neg—
alovirus, histoplasrnarnicroabscess). Fungal infection, es-
(cﬁﬁrploandamgdplﬂhmmrmt atcpimmanmainﬁeof
tion, is the most common cause of abscess formation
(337). Simultaneous infection by more than one rnicroor—
ganism occurs occasionally. Bacterial infections of the
CNS are uncommon, but HIV encephalitis is common
(335). Primary Cl>fS lymphoma or lymphoma 1neta—
static from extracfanial sites occurs in a variable propor-
tion of the cases (336"338). There are cases in which in-
fection and"umor odcur in the same patients (339).
Spinal cord involvement occurs with demyelination in
the lon£ tracts of posterior columns (340).
Between 50 and 60 percent ofpatients with AIDS may
be expected to develop a neurological complication
(341). Approximately 10 percent of patients develop in-
tracranial mass lesions, and, in about 25 percent ofthese
patients, the lesion is identified before the diagnosis of
AIDS is established (342). The two most common mass
lesions are toxoplasmosis abscess and lymphoma. These
lesions have neurosurgical implications in terms of the
question of biopsy versus medical management.
A large proportion of both the AIDS and non—AIDS
population is seropositive for toxoplasmosis, indicating

previous subclinical infection. In patients with AIDS, in-
fection with the protozoan, Toxoplasma gondii, appears
to result from reactivation of a prior latent infection
(343). The clinical manifestations of CNS involvement,
especially focal seizures, suggest a focal process. There
may or may not be a focal neurological abnormality.
Lumbar puncture is not helpful, because the CSF may
show only a nonspecific lymphocytic pleocytosis. Exa1ni—
nation of the CSF, however, is useful in excluding rnenin—
gitis caused by other organisms, including Cryptococcus
neoformans (343). On the other hand, clinical judgment
needs to dictate whether the risk of the lumbar puncture
producing cerebral herniation in the presence of a space-
occupying intracranial mass lesion is worth the inforrna—
tion concerning the question of meningitis. Measure-
ment of CSF antibody to T. gondii is not diagnostically
helpful (343). AIDS patients with toxoplasmosis gener-
ally have evidence ofpast infection (IgG antibody); there-
fore, although serologic testing has limited value for the
diagnosis of toxoplasmosis in AIDS patients, absence of
the IgG antibody to T. gondii tends to exclude that diag-
nosis (344).
Both CT and MRI scanning are useful in dernonstrat—
ing toxoplasmosis in the brain. The lesions may be soh—
tary, but they are usually multiple. The basal ganglia are
the most common site, but the lesions may occur in any
portion of the brain including the cerebral cortex, cere-
bellum, and brainstern (345,346). There is considerable
surrounding edema. For CT scanning, double—dose con-
trast increases the sensitivity of the imaging; ring en-
hancement is common (Fig. 4). MRI may be slightly
rnore sensitive than CT scanning, but it is not more diag-
nostically speciﬁc (346). RN brain scintigraphy (isotope
brain scan) may also demonstrate localized intracranial
infection (347), although resolution is inferior to that of
CT or MRI scanning.
If the diagnostic studies do not reveal a clear—cut diag-
nosis of toxoplasmosis, the question of carrying out a
biopsy for definitive diagnosis arises. This can be carried
out with reasonable safety by CT—guided biopsy tech-
nique (under local anesthesia) or by open craniotorny
with the aid of ultrasound imaging for localization of the
lesion (343). Another option is that ofplacing the patient
on a trial of the drug combination ofpyrimethamine and
sulfadiazine. This regimen is highly effective, with clini-
cal improvement and shrinkage of the lesions on CT
scan usually apparent within one to two weeks. Treat-
ment rnust be continued indefinitely. If there is no irn—
provement within two weeks, biopsy may then be consid-
ered (342,343).
In patients with AIDS, primary CNS lymphomas oc-
cur in about 2 percent of cases, and in about one—third,
the tumor is the first manifestation of AIDS (342). The
patients may present with confusion, headaches, visual
disturbance, memory impairment, and focal neurologi-
cal abnormalities such as hemiparesis (342,348). Sci-
CNS INFECTIONS . 3
FIG. 4. CT scan with IV cor Iancement, showing ring
enhancement of a lesion in tr.e region of thalamus/basal gan-
glia (arrow). The patient was a38—year—o|d woman from Haiti
who presented with focal seizures, a rapidly progressive he-
miparesis. and a dedning level of consciousness; she was
found to be HIV-positive, CT—guided siereotaxic biopsy re-
vealed a toxoplasmosis abscess. She was then treated with
pyrimethamine and sulfadiazine, with temporary improve-
ment in her neurological status, but she subsequently deter-
iorated and died.
zures occur in about one—third of the patients. CT or
MRI scanning reveals mass lesions that are multiple in
about two—thirds of the cases; the lesions are usually con-
trast—enhancing on CT scanning. MRI is reported as be-
ing rnore sensitive than CT and may show more areas of
involvement, but it is not more specific in differentiating
the lesion from other AIDS—related diagnostic possibili-
ties (349).
Other AIDS—related diagnostic possibilities in patients
with focal lesions are cerebral toxoplasmosis, progressive
multifocal leukoencephalopathy, fungal or bacterial in-
fection, and hemorrhage (350).
Lumbar puncture for CSF examination may show
slight increase in protein and mild lyrnpocytic pleocyto-
sis (348). CSF cytology generally does not reveal abnor-
mal cells. Because the CSF findings are nonspecific, the
main value of lumbar puncture in diagnosis of CNS lyin-
phoma is the ruling out of meningitis such as cryptococ—
cus. As mentioned previously, the risk of cerebral her-
niation has to be considered in judging whether to cany
out lumbar puncture where the CT or MRI scan shows
significant intracranial mass, especially if the scan shows
a hemispheral shift.
For definitive diagnosis, a CT—guided stereotaxic
biopsy may be performed. However, because toxo-

204 / CHAPTER 10
plasma abscesses are the most common type of cerebral
mass lesion in patients with AIDS and the most arnena—
ble to treatment, Rosenblurn, Levy, and Bredesen recorn—
mend a three—week antibiotic trial with pyrimethamine
and sulfadiazine for any patient with AIDS and intracra—
nial masses (342). Steroids may also be given brieﬂy if it
is necessary to control cerebral edema. Clinical irnprove—
ment and shrinkage of the lesions confirm toxoplas1no—
sis as a diagnosis. However, if the patient is not likely to
survive the three—week antibiotic trial or if any of the
masses fail to respond to the antibiotic treatment, then
biopsy is recommended. Furthermore, because toxo—
plasrnosis lesions are usually multiple, a biopsy should
probably be performed for solitary mass lesions.
Radiation therapy is the recommended treatment for
CNS lymphoma, possibly in conjunction with chemo-
therapy and steroids (351). Although the neoplasm re-
sponds favorably to radiation therapy, patients usually
die of other AIDS complications.
Osteomyelitis of the Skull
The skull is relatively resistant to infection, and the
occurrence of infection is usually associated with one of
the following:
1. Infection of an adjacent air sinus, usually the frontal
sinus;
2. Head trauma with scalp laceration, particularly when
associated with skull fracture; or
3. Postoperative infection, following a craniotomy.
One series reported a 5 percent postoperative infection
rate following craniotomy (352), and another series re-
ported a 7 percent incidence of craniotomy infections
(353). In the latter series, bone flap infections repre-
sented rnore than half of all infections after supratentor—
ial craniotomy. and bacterial meningitis accounted for
more than half of the infections following suboccipital
craniotomy and translabyrinthine operations.
Cranial osteomyelitis may be a low—grade infection
limited to the skull, or it may be associated with epidural
or subdural empyema. with life—threatening potential. In
acute osteomyelitis of the skull, the patient may have
fever and localized pain, tenderness, and swelling in the
area of the involved bone. On plain x—rays, localized
bone destruction may not become evident until two
weeks after the onset of the osteomyelitis (Fig. 5). Al-
though the area of infected bone may be identified on
plain skull films, additional studies, including isotope
bone scan and CT—scan of the skull, may be needed to
clarify the diagnosis. The offending organism is usually
Staphylococcus, either S. aareas or S. epidermidis, or
mixed flora (354).
In acute osteomyelitis, antibiotics are the main treat-
ment. In both the acute and chronic forms, it is irnpor—
FIG. 5. Plain skull film showing area of chronic osteomyelitis
in the frontal bone (arrows) in a patient who had sustained a
depressed skull fracture and frontal paranasal sinus injury.
(Courtesy of Dr. George Craven, Department of Neurosur-
gery, Louisiana State University Medical Center.)
tant to obtain a culture of the infected area either by
needle aspiration or by open operation. Treatment of an
infected contiguous source, such as frontal sinusitis, is
also necessary. It has been recommended that antibiotics
be given intravenously for one to two weeks, then given
orally for 6 to 12 weeks. Intermittent antibiotic serum
levels should be obtained while the patient is on oral
therapy (355). Alternatively, some authors prefer a bi-
weekly course of intravenous antibiotics, with no need
for continuation with oral drugs (A. Molavi, Hahne—
rnann University, personal communication). Despite the
use of antibiotics, chronic osteomyelitis is best treated
also with surgical resection (craniectomy) of the in-
volved bone (354).
SPINAL ABSCESS
Pyogenic Infections
Vertebral Osteomyelitis
Pyogenic vertebral osteomyelitis is commonly asso-
ciated with antecedent bacterial infection elsewhere in
the body. Bacteria from the primary site, such as pelvic
or urinary tract infection, spread hematogenously to the
vertebral column, either via arteries or via the veins of
Batson's plexus (356-358). A septic embolus produces a
locahzed bone infarction, which results in the develop-
ment of osteomyelitis (359). The richly vascularized ver-
tebral body end plate region is the commonest site of
initial infection from hematogenous spread. This dis-
order occasionally follows penetrating trauma or spinal

surgery. Staphylococcus aareas is the most common or-
ganism responsible for vertebral osteomyelitis, but
gra1n—negative organisms have also been implicated
357,360—362). Pseadomonas aeraginosa is commonly
isolated from vertebral osteomyelitis in heroin ad-
dicts (363). I
In children, spinal infection usually has an abrupt on-
set, with malaise, fever, back pain, and spinal tenderness.
In adults, however, symptom onset is usually gradual,
and up to three months may be required to make the
diagnosis (364,365). In both adults and children, diagno-
sis is commonly delayed, owing to the nonspecificity of
the symptoms. For example, spinal pain secondary to
vertebral osteomyelitis may be the primary 1nanifesta—
tion of infection elsewhere, such as endocarditis
( 366,367). Osteomyelitis should be included in the dif-
ferential diagnosis of persistent or worsening backache
in elderly patients with degenerative spinal osteoarthritis
(368). In patients undergoing long—term hemodialysis,
however, plain x—ray changes in the spine suggest osteo-
myelitis but, on investigation, turn out to be "pseudoin—
fection." The cause of these changes is not known (369).
The absence of a prevertebral soft—tissue mass on MRI
scanning in hemodialysis patients suggests that the spi-
nal radiographic changes are not due to infection (370).
Osteomyelitis is similarly considered in patients with os-
teoporosis and vertebral body collapse who have back
pain, fever, and elevated sedimentation rate (371). Cer-
vical osteornyelitis is considered a diagnostic possibility
after anterior spine surgery (372). penetrating wounds of
the neck (373), panfacial trauma (374), or tracheo-
esophageal puncture for voice rehabilitation (375).
There is little or no fever, and adults usually have n/o
malaise. Back pain is present in about two—thirds of the
cases, particularly if the mobile cervical and lumbar ar-
eas are affected rather than the ﬁxed, thoracic spine.
Usually, on palpation, point tenderness is evident at the
involved site. In adults, the leukocyte count is seldom
raised, but the ertlirocyte sedimentation rate (ESR) is
usually elevated. Some authors have noted an associa-
tion of vertebral osteomyelitis with diabetes (157,376),
but others have not (361). A raised sedimentation rate is
said to be the best clue that backache in a diabetic patient
is due to something other than benign osteoarthritic
changes (376).
Thoracic and lumbar vertebrae are most frequently
involved; the vertebral bodies are more commonly af-
fected than the posterior elements. Generally, rnore than
one spinal level is affected. Pus from an infected vertebra
may form a paravertebral abscess or, more importantly,
an epidural collection that may compress adjacent
neural structures. Collapse of a vertebral body may result
in gibbus formation that may impinge on the spinal cord
or cauda equina. Either of these mechanisms may lead to
paralysis. In one series, 3 of 28 patients with vertebral
body infection subsequently developed paralysis (361).
CNS INFECTIONS / 205
Plain x—ray findings lag behind signs and symptoms by
two to eight weeks (126). These findings consist of bone
rarefication, loss of bony trabeculation close to the caiti—
laginous plate, and narrowing of the vertebral disc space
between involved adjacent vertebrae. An important x-
ray observation differentiating osteomyelitis from
cancer metastasis is the finding that the intervertebral
disc is commonly destroyed by osteomyelitis, whereas it
is generally preserved in metastatic disease (377). There
are exceptions to this rule, however, so intact vertebral
endplates on MRI scanning do not necessarily exclude
osteomyelitis in favor of metastatic disease (378). Verte-
bral body collapse is common. In chronic infections,
there may be rapid bone regeneration with the develop-
ment of dense new bone. RN scanning is sensitive in
diagnosing infection in the jirst several weeks of verte-
bral osteoinyelitis. The combination of an abnormal Tc-
991n bone scan"ana an abnormal Ga—67 scan, showing
focal uptake in the spine, are reasonably speciﬁc for diag-
nosis of vertebral osteomyelitis (379). On the other hand,
the finding of In—l 1 1 labeled leukocytes (In—1 11 WBC) is
less specific (380). CT scanning may show bony abnor-
malities before plain x—rays do (381), and it has the ad-
vantage over RN scanning of distinguishing bony from
disc space involvement. CT scanning after intravenous
contrast injection enhances the rim around an epidural
abscess, which adds to the usefulness of this modality
(3 82). MRI scanning has the same accuracy and sensitiv-
ity as radionuclide scanning in detecting osteomyelitis
(377). MRI scans show obliteration of the margin be-
tween the disc and the vertebral end plates (383) (Fig. 6).
RN scanning is less subject to motion degradation than
MRI scanning. If patients cannot tolerate MRI scanning
because of claustrophobia, RN scanning can be per-
formed (377). Myelography with water—soluble contrast
followed by CT scanning is useful in outlining epidural
abscess, but the value of myelography is declining be-
cause of the availability of RN, CT, and MRI scanning.
The responsible organism may be identiﬁed by blood
culture in cases of acute vertebral osteomyelitis, but is
usually negative in chronic osteomyelitis (384). If blood
cultures are negative, it is recommended that the respon-
sible organism and its susceptibility to antibiotics be
identified. This can be accomplished by percutaneous
needle aspiration under fluoroscopic or CT guidance or
by open biopsy. Percutaneous CT guidance has been re-
ported as safe, accurate, and superior to fluoroscopic
guidance (3 84-3 87). Both aerobic and anaerobic culture
should be carried out, as well as culture for tuberculosis,
fungi, and search for parasites.
Treatment of vertebral osteomyelitis without neuro-
logical deficit consists of bed rest and immobilization,
along with antibiotic therapy based on meticulous sus-
ceptibility testing of the offending organis1n(s) (2). Paren-
teral antibiotics are given for six to eight weeks, and oral
therapy should continue for an additional eight weeks

206 / CHAPTER 10
FIG. 6. MRI scan in 37-year-old patientwith a history of drug
addiction presenting with thoracic spinal pain and rapidly pro-
gressive paraparesis. The MRI scan suggests osteomyelitis,
showing vertebral body collapse, destruction of the end-
plates, and spinal cord compression. The involved vertebral
bodies and intervening disc were resected by a thoracotomy
approach, and a strut bone graft was placed at the site of the
vertebral corpectomies. The patient had an excellent recov-
ery of neurological function. The organism proved to be
Staphylococcus, for which she was placed on an antibiotic
regimen.
(388). External immobilization may prove a useful ad-
junct to prevent bony collapse and may increase patient
comfort. Significant paravertebral abscesses may require
drainage. A metal stabilization rod may be implanted at
the time of surgical drainage to control pain and to per-
mit postoperative mobilization (389). Should the spinal
cord be compressed by epidural pus or gibbus, deco1n—
pression of the spinal cord will be necessary either by
laminectomy or by an anterior or lateral approach. How-
ever, patients with spinal epidural abscess who are in
poor medical condition or are without neurological defi-
cit may be treated with antibiotics alone without sur-
gery (388).
Owe Space Infection
Patlzopliysio logy
Infection of the disc space is a relatively uncommon
complication following open (390) or percutaneous
(391) excision of a herniated disc (usually in the lumbar
area) (390) or after lumbar chemonucleolysis (392).
Somewhat more common is the spontaneous develop-
ment of disc space infection without prior spinal surgery.
The latter form is thought to be produced by the hema-
togenous spread from an infective source elsewhere in
the body, although a speciﬁc source often remains unde-
termined. The spontaneous forrn of disc space infection
tends to be more common in children than in adults,
which has been attributed to the observation that the disc
space early in life is well supplied with blood vessels from
the adjacent vertebrae and that these vascular channels
gradually disappear by the second or third decade. The
normal adult disc is relatively avascular, which probably
accounts for the lower frequency of blood—bome infec-
tion of the disc in adulthood.
Staphylococcus anrens is nearly always the offending
organism in children. This bacterium also predominates
in adults, but a wide variety of other organisms may be
implicated, and hence it is important to isolate the organ-
ism, especially in adults, before making a decision re-
garding selection of antibiotic therapy.
Clinical Manifestations
Discitis can affect the interyertebral disc at any level of
the spine but is most common in the lumbar region.
Children may be affected from approximately one year
of age through adolescence. There is a higher incidence
of discitis in diabetic adolescents. Children commonly
present with low—grade fever, irritability, and malaise. If
they are able to describe symptoms, back pain is a pro1ni—
nent complaint, and paravertebral muscle spasm is a sig-
nificant finding on examination. Sometimes the child
will present with a limp or will refuse to walk, and the
spinal origin of the problem may be missed unless the
examiner palpates the spine in search ofpoint tenderness
and muscle spasm.
In adults with spontaneous discitis, the onset is gener-
ally rnore insidious, extending over weeks to months be-
fore the diagnosis is suspected. Patients cornplain of
well—localized back pain; if the lesion is in the lumbar
spine, there is referred pain down one or both legs or to
the hip or groin. As in children, there is localized spinal
tenderness, paravertebral muscle spasm, and limitation
of spinal motion. Neurological impairment is unusual in
children but is more likely in adults, secondary to an
extradural inflammatory reaction with spinal cord or
nerve—root compression. In recent years it has been ob-
seryed that intravenous drug users appear to be predis-
posed to discitis.
Postoperative disc space infection is also difficult to
diagnose because patients routinely have back pain and
muscle spasm after surgery. However, if the spasm is
severe and prolonged (beyond a matter of weeks), disc
space infection should be considered, despite the ab-
sence of any evidence of wound infection.

Diagnostic Procedures
The white blood cell count in children and adults is
often normal or only moderately elevated, but the eryth-
rocyte sedirnentation rate is almost uniformly elevated.
Blood cultures are positive in about one—quarter of pa-
tients with pyogenic infection of the disc space; when
positive, the blood culture can be used as a guide for
antibiotic therapy and can obviate the need to/obtain a
culture from the affected disc space.
Plain x—ray films of the involved areas of the spine
show localized disc space narrowing as the first radiologi-
cal sign, but the films may be normal until several weeks
after onset of the symptoms. Narrowing is followed by
blurring of the end plate and irregularity and lytic de-
struction of the subchondral portion of the vertebral
body. In later stages, after many months of healing, there
is sclerosis and spontaneous interbody fusion. Lamino—
grarns or CT scans are helpful in characterizing the le-
sion. MRI scanning of disc space infection shows loss of
disc height, irregular disc margins, and increased signal
from the adjacent vertebral bodies (393). Radioisotope
scanning shows a localized area of increased uptake; spot
views using the pin—hole collimator provide greater diag-
nostic detail. The bone scan, however, is of less value in
postoperative discitis, because increased uptake is nor-
mally expected following disc surgery. Reliance in the
diagnosis of postoperative infection is placed on serial
plain x—ray films and CT scans. An experimental study
in animals comparing MRI scanning to radioisotope
imaging in pyogenic infection of the intervertebral disc
revealed that MRI is more sensitive than isotope scan-
ning, particularly in the early stages of the infec-
tion (394).
Percutaneous needle aspiration of the affected disc
space should be seriously considered in an effort to ob-
tain material for culture; identification of the offending
organism is crucial in order to select appropriate antibi-
otics, unless the blood culture has been positive (2). Disc
space culture in children is said to be less vital than in
adults because the organism in children is likely to be
Staphylococcus aureus. A problem with simple needle
aspiration is that the infection is usually not purulent,
and positive cultures are obtained in no more than one-
third of the cases. If no purulent material can be aspi-
rated, l to 2 ml of saline may be injected through the
needle and the saline reaspirated. An alternative tech-
nique that yields positive cultures in about two—thirds of
the cases involves use of a trephine biopsy needle, which
can be introduced percutaneously under local or general
anesthesia or as an open surgical biopsy. This can be
done under fluoroscopic or CT guidance. The biopsy/
aspiration technique not only provides tissue for l1istolog—
ical examination but also increases the likelihood of ob-
taining a positive culture. Histological verification of
infection is valuable in patients in whom an organism is
not isolated; a further advantage is the occasional finding
CNS INFECTIONS / 207
of an unsuspected tumor. To place the diagnostic proce-
dures in perspective, early radioisotope bone scan and
early biopsy of the affected disc are recommended.
Treatment
The key to management is the administration ofparen—
teral antibiotics for four to six weeks, basing the selection
of antibiotic on blood culture or biopsy/aspirate from
the affected disc space. Although antibiotics have proven
value for the treatment of vertebral osteomyelitis, there
is a question of the effectiveness of antibiotics for disc
space infection. At least in the normal, noninfected disc,
antibiotics do not penetrate the disc (395), but it is not
clear whether penetration may occur in the presence of
discitis. Despite these reservations, the current general
consensus favors use of antibiotics in disc space infec-
tion. Bed rest is recommended for comfort until the
acute symptoms of back pain and spasm subside. Rigid
immobilization in a body cast is probably unnecessary.
After the initial acute phase, the patient is permitted to
ambulate with a simple spinal support for comfort. The
erythrocyte sedimentation rate and plain x—ray films of
the spine monitor resolution of the infection (396).
Children tend to recover over the course of a few
weeks to several months; the course in adults may be
more prolonged. In individuals, usually adults, in whom
the symptoms persist and the x—ray films fail to show
bone healing, open surgical debridement of the disc can
be carried out; a spinal fusion might be added at the time
of the disc debridement. Some authors recommend early
surgical treatment in some cases, which appears to eradi-
cate the disease (390), In the unusual circumstance of
neurological impairment secondary to spinal cord or
nerve root compression, surgical decompression is inan-
datory unless there are general medical contraindica-
tions. In general, the long—term outlook for most patients
with disc space infection is favorable.
Pyogenic Spinal Epidural Abscess
In two U.S. hospitals, the incidence of spinal epidural
abscess was between 0.2 and 1.2 per 10,000 admissions
from 1947 to 1974 (397). Acute or chronic forms have
been described, depending on whether the clinical
course evolves over a few days or several weeks. Pyo-
genic epidural abscesses may arise hematogenously or by
spread from adjacent vertebral osteornyehtis.
Etiology and Pathogenesis
Skin infections are the most common antecedent
source (397-399). Staphylococcus aureus is the most
common infecting organism, but streptococci and grain-
negative bacteria from preexistent urinary tract infec-

208 / CHAPTER 10
tions may also be responsible. Spinal trauma occurring
just before the onset of symptoms has been reported in
10 to 40 percent of patients; there is a question whether
small, clinically insignificant, traumatic epidural hema-
tornas subsequently become colonized with bacteria
(397,398).
Epidural abscesses can involve any portion of the
spine, but the thoracic region ismost commonly in-
volved. The pus usually lies dorsally because epidural
fat, which is susceptible to bacterial invasion, lies dor-
sally. The dura is closely'approxirnated to the vertebral
bodies anteriorly (397,398). Anterior epidural abscesses
were found in 7 of 39 cases reviewed by Baker, Ojemann,
Swartz, and Richardson (397). In acute hematogenous
cases, granulation tissue admixed with pus extends ax-
ially over an average of four spinal segments. Chronic
epidural abscesses tend to have an even more extensive
axial spread than do acute lesions. The dura itself is resis-
tant to bacterial penetration, and spread of infection to
the subdural or subarachnoid spaces is rare.
Intuitively, one would imagine that the space—occupy—
ing effect of the epidural pus compromises the spinal
cord by pressure. Often, however, the neurological in-
volvement appears out of proportion to any observed
pressure effect, and it has been proposed that the neuro-
logical sequelae result from epidural arterial or venous
thrombosis, with resultant spinal cord infarction (400).
Clinical Manifestations
Individuals with acute abscesses are febrile and septic,
but those with chronic processes may be afebrile and
appear relatively well. Spinal epidural abscesses tend to
evolve through four clinical stages: (1) focal spinal pain
and tenderness; (2) root pain; (3) paresis; and (4) paraly-
sis (399). In the acute case, this sequence of events occurs
over an average of seven days, whereas chronic cases
may evolve over weeks or months. Once paresis ensues,
however, total paralysis generally occurs within 24
hours. Because the ultimate quality of neurological recov-
ery varies inversely with the degree and duration ofpare—
sis orparalysis, spinal epidural abscess is a true neurosur-
gical emergency. Immediate operative decompression is
mandatory.
If an individual has the classic clinical syndrome plus
evidence of vertebral bone destruction on plain x—rays,
the diagnosis and approximate locus will be highly suspi-
cious for epidural abscess. In acute cases, however, no
osteomyelitis will be evident, and, although the diagnosis
may be suspected, the exact locus may be in question. In
either case, but particularly in acute cases, imaging by
CT scan, MRI, or myelography is indicated in order to
delineate the rostral and caudal spread of epidural pus. If
myelography is carried out, contrast agent may be in-
jected above or below the suspected site of the lesion to
outline the upper and lower limits of the abscess. Care
must be taken when advancing the spinal needle to avoid
introducing bacteria from the epidural to the subarach—
noid space. If a spinal puncture is done and spinal fluid
examined, the CSF may be turbid or xanthochromic.
Pleocytosis may be evident, and the protein level may be
elevated. The glucose is often reduced even in the ab-
sence of meningitis.
The differential diagnosis of spinal epidural abscess
includes meningitis, spinal subdural abscess, acute trans-
verse rnyelitis, herniated intervertebral disc, vertebral or
spinal cord tumors, and vascular lesions.
Treatment
Antibiotics are started when the diagnosis is suspected
and while the patient is being prepared for surgery. Be-
cause the overwhelming number of cases are due to
Staphylococcus aureus, empirical therapy should begin
with nafcillin unless an alternative etiology is suggested
by history or laboratory findings of an antecedent infec-
tion due to another organism (A. Molavi, Hahnemann
University, personal communication). Pyogenic spinal
epidural abscess is quite amenable to drainage. The sur-
gical approach depends on the location of the abscess in
the spinal canal. At operation, a specimen ofpus or gran-
ulation tissue is obtained for gra1n—stain, aerobic and an-
aerobic cultures, and sensitivities as well as for fungal
and mycobacterial cultures and sensitivities. At surgery,
free pus in the epidural space is drained, and the epidural
space is irrigated with saline/antibiotic solution. Hulme
and Dott recommend excision of chronic granulation
tissue to prevent subsequent dural stricture by scar tissue
(399). In the series of Baker and associates, when a
chronic epidural abscess was found, the laminectomy
wound was closed at surgery, without postoperative diffi-
culties. When an acute pyogenic epidural abscess was
found, the wound was either packed and left open for
subsequent secondary closure or was loosely closed over
soft irrigation catheters that could be used to irrigate the
epidural space with antibiotic solution during the postop-
erative phase (397). Once the speciﬁc organism is identi-
ﬁed and its sensitivities determined, a speciﬁc antirnicro—
bial agent may be selected for further therapy.
Acute hematogenous abscesses are not usually asso-
ciated with vertebral body destruction and spinal instabil-
ity. Ifvertebral osteomyelitis coexists with body collapse
and gibbus formation has occurred, or if spinal instabil-
ity is present because of the infection, later stabilization
procedures may be necessary.
Prognosis
Before the use of antibiotics, the mortality for epidural
abscess ranged from about 30 to 90 percent (398,399);

recent mortality is approximately 18 percent (397). In
general, the neurological outcome depends on the degree
of cord function remaining prior to drainage and decorn—
pression. Patients with no paresis or with weakness last-
ing less than 36 hours often have excellent neurological
recovery. Those who have been paralyzed for longer
than 48 hours generally do not recover neurological
function. Baker and colleagues reported on the outcome
(with aggressive diagnosis and surgery) of 32 patients
who survived their epidural abscesses: 4 were perma-
nently paralyzed, 5 had paresis, and 23 were neurologi-
cally intact (397).
Spinal S ubdural Empyema
Spinal subdural ernpyerna (abscess) is a rare condi-
tion. In 1984, Probst and Wicki summarized 14 cases
culled from the literature and added three of their own
(401). Analysis of these cases led to the conclusion that
the origin ofthe subdural infection was most often hema-
togenous but that penetration of the dura from a contigu-
ous epidural infection, lurnbar puncture, injury, or con-
genital deformity (e.g., dermal sinus tract) could also
account for the infection. Staphylococcus has been the
most common bacterium; diabetes mellitus is a corn-
mon predisposing cause. Thoracic, thoracolumbar, and
lumbar areas were all involved with about equal fre-
quency, and several cases occurred where pus extended
in the subdural space from cervical to sacral areas.
Pathologically, the inflammation may spread into the
subarachnoid space. The arachnoid and dura are thick-
ened. Pus is present subdurally, and granulation tissue is
fixed not only to the dura but also to the spinal cord. The
more acute the case, the greater the amount of pus; the
longer the duration of symptoms, the more likely the
occurrence of granulation tissue. Infection involves the
extra— and intramedullary blood vessels as well. This
leads to vascular narrowing and occlusions, particularly
venous thrombosis and hemorrhagic infarctions. The
nerve roots themselves may be swollen and demyelin—
ated. The white matter of the spinal cord is particularly
involved.
Clinically, patients have fever and generalized signs of
infection. Signs of meningeal irritation may be evident.
There may be back pain and spinal cord (myelopathy) or
radicular symptoms and signs. The neurological findings
may be secondary to interference with blood supply or
may be due to direct neural compression.
Upon lumbar puncture, frank pus may be returned.
Because of compression of the subarachnoid space by
the pus, it may be impossible to obtain CSF. When CSF
is found, it is often xanthochromic; the cell count is gen-
erally elevated. Protein is usually elevated and CSF glu-
cose diminished. Occasionally, however, patients with
subdural abscesses have normal CSF.
CNS INFECTIONS / 209
Plain x—rays generally show no bone destruction. My-
elography demonstrates an irregular filling defect or a
block that may be undifferentiable from epidural ab-
scess. Surgical decompression is essential. Pus, when
found, is removed by irrigation. If possible, granulation
tissue is removed, but not granulations densely adherent
to the spinal cord. Probst and Wicki also recommend
early rehabilitation and, of course, treatment of any un-
derlying infection (40l). Of 15 patients who underwent
surgery, six were cured, five improved, and four died.
Intramedullary Pyogenic Spinal Cord Abscess
Intramedullary spinal cord abscesses are found in ap-
proximately l of every 40,000 autopsies. The peak inci-
dence is in the first and third decades; males are more
commonly affected than females. The thoracic spinal
cord is most commonly involved. Among 55 reported
cases, 42 individuals had a single intramedullary abscess,
and the remainder had multiple lesions (402). The pre-
dominant organisms were Staphylococcus and Strepto-
coccus. Midline spinal skin defects, such as dermoid
sinus, and antecedent infections of the respiratory tract,
spine (including fractures), heart valves, genitourinary
tract, or soft tissues had been present in 80 percent of
patients. No apparent infected focus could be found in
the others. Bacteria can reach the spinal cord by (1) di-
rect implantation secondaiy to trauma, (2) the blood-
stream, or (3) lymphatics from the retropharyngeal
space, mediastinum, or abdominal cavity. Such lyin-
phatics course along spinal nerves and communicate
with the spinal subarachnoid space and Virchow—Robin
spaces. Acute intramedullary abscesses are similar to
other central nervous system abscesses, but they lack the
widespread venous infarction seen with epidural ab-
scesses. This may account for their often favorable prog-
nosis.
Clinically, intramedullary abscesses can have an
acute, subacute, or chronic course. Neurological syrnp—
toms and signs vary according to abscess location. Acute
cases have fever, and there may be transverse rnyehtis.
Pain in the neck or back, urinary incontinence, dysesthe—
sias, and monoparesis that progresses to paraparesis or
quadraparesis typically occur. Patients with chronic in-
tramedullary abscesses have a stuttering course sirnulat—
ing that of a spinal tumor. Examination of the cerebrospi—
nal fluid is generally unrewarding and may be
misleading; pleocytosis may suggest meningitis. Myelog—
raphy may demonstrate a spinal block and suspicion of
an intraspinal mass.
Surgical therapy consists of larninectorny and incision
and drainage of the abscess. Occasionally, an intraspinal
abscess will masquerade as arachnoiditis, and, therefore,
when localized spinal arachnoiditis is discovered during

210 / CHAPTER 10
spinal cord surgery, this should raise suspicion that a
spinal cord abscess may be present. As in the case of
abscesses in general, antibiotics are started as soon as
infection is recognized. When obtained, the pus is grain-
stained and cultured for aerobic, anaerobic, and rnyco—
bacteria as well as fungi for selection of specific anti1ni—
crobial therapy. Postoperatively, patients are followed
closely because of a high recurrence rate. Twenty of the
55 patients cited above had drainage of the intrarnedul—
lary abscess; of these, five patients died (all before the
advent of antibiotics), six recovered neurologically, six
showed some improvement, and three remained un-
changed.
Spinal Tuberculosis
Tuberculosis may involve the vertebral column and
the epidural space, dura, arachnoid, or spinal cord
(206,342,403). Often, the disease is confined to one ana-
tomic area (404).
Tuberculous Spondylilis (Pott's Paruplegia)
Generally, tuberculous spinal infection involves the
vertebral body (Pott's tuberculous spondylitis). Tuber-
culous destruction of the spine, with subsequent spinal
cord compression, continues to be a common disease in
developing nations. Mathai and Chandy indicated that
in India, 42 percent of their spinal operations for non-
traurnatic paraplegias were for compression consequent
to tuberculous spondylitis (404). In the United States,
this disease is rare. Tuberculous spondylitis most fre-
quently involves the lower thoracic and upper lumbar
vertebrae. The disease most commonly affects the verte-
bral body and is usually limited to one vertebra. Neuro-
logical complications occur in 10 to 25 percent of pa-
tients, particularly if the thoracic spine is involved.
There are two categories of Pott's paraplegia: early—onset
cases, in which the neurological dysfunction begins
within two years of the tuberculous spondylitis; and late-
onset paraplegia, with the deficit beginning after two
years. Early cases occur when the disease is active,
whereas late cases are associated with a recurrence of the
infection following apparent quiescence.
The disease usually starts in the first decade of life but
becomes symptomatic and is diagnosed during the third
decade. A case has been reported of spinal tuberculosis
after a closed fracture (405); the trauma appeared to pre-
dispose the involved vertebrae to hematogenous infec-
tion. Though no distinctive pattern of neurological signs
or symptoms exists with Pott's disease (216), pain and
local spine tenderness occur in more than 70 percent of
patients. Radicular pain is common. The cause of the
cord compression may be epidural abscess, bony corn-
pression, or both.
Radiographically, early vertebral body decalciﬁcation
is seen about the disc with slight diminution of the disc
space. Later, frank vertebral erosion and collapse occur,
and paravertebral or psoas abscess may appear. Sclerotic
changes may also be present because of concomitant
bone regeneration and fusion of vertebral bodies. Casea—
tion beneath the anterior spinal ligament causes scallop-
ing of the anterior vertebral border. CT scanning shows
the expected vertebral body involvement but, in addi-
tion, can depict paraspinal abscess and an epidural tu-
berculous collection. Contrast enhancement may aid in
their delineation. CT is also helpful for guiding aspira-
tion of suspected areas of infection (406). Myelography
often reveals a block at the infection site.
Spinal tuberculosis can be treated medically or surgi-
cally. Friedman treated 64 patients with Pott's disease by
— prolonged administration of antituberculous drugs, bed
rest, and spinal bracing (406). Spinal fusion was not
done, and laminectomy was reserved for eight patients
with paresis. Fifty patients were cured by this approach,
but 10 others had relapses, and four died. Hodgson and
. Stock, on the other hand, advocate direct operative at-
tack on tuberculous vertebrae (407). The diseased bone
is approached anteriorly or laterally and is resected.
Granulation tissue around the dura is stripped away, and
the vertebral bodies are stabilized by strut grafts. They
report improved neurological function even in cases
with paralysis. In 1960, they reported the operative re-
sults on 35 paralyzed patients. Twenty—six had complete
neurological recovery after operation. Graft complica-
tions (slippage, fracture, angulation) occurred in 13 pa-
tients, and four died. Subsequently, Hodgson and col-
leagues also reported that 19 of 23 paraparetic children
made complete neurological recoveries after decornpres—
sion and fusion, including 19 of 20 who had been para-
lyzed (408). Antituberculous drugs are given for at least
18 months after operation. It would appear that Hodg-
son's patients had more serious bony and neurological
involvement than did Friedman's.
Hsu and Leong reported treatment of 40 patients with
tuberculosis of the cervical spine (409). Forty—three per-
cent of the patients had evidence of cord compression,
mainly from pressure by epidural abscess. Surgical ther-
apy was generally by anterior excision of the diseased
bone, followed by grafting. In addition, all patients re-
ceived streptomycin for three to nine months. All pa-
tients recovered spinal cord function. Four patients un-
derwent posterior fusion initially, but all eventually
required anterior excision and grafting because of pro-
gressive kyphosis or persistence of vertebral body infec-
tion. Larninectorny, therefore, is not recommended for
Pott's paraplegia because the cord is compressed from its
anterior aspect. However, in 10 percent of cases, tuber-
culous spondylitis involves the neural arch instead of the
body. In the latter situation, the spinal cord may be corn-
pressed frorn its dorsal aspect instead of anteriorly. Ra-

diographically, such cases may be mistaken for epidural
metastasis. Patients with neural arch involvement invari-
ably have associated dorsally placed epidural abscesses
and are best treated by laminectomy and antituberculo—
sis therapy (410).
Tuli reported on the results of aggressive medical and
surgical therapy in 200 cases of spinal tuberculosis (411).
Medical treatment for adults consisted of streptomycin,
sodium para—arninosalicylate, and isoniazid. Patients
were placed on a firm bed or used a plaster j acket. Grad-
ual mobilization of the patient in a spinal brace was be-
gun after six to nine months. Paravertebral abscesses
were aspirated or drained. Decompression of the cord
was eventually performed on patients on medical ther-
apy who failed to show progressive recovery of neurologi-
cal function. Ninety—four percent of the patients without
neurological deficit recovered without surgery, and 38
percent of those with neurological involvement also re-
covered without operation. According to Kaufman,
Kaplan, and Litman, only 5 to 20 percent of cases of
Pott's disease are complicated by neurological defi-
cit (412).
The regimen of choice for tuberculosis is a cornbina—
tion of isonazid, rifarnpin, and pyrazinamide for two
months followed by a four—month or longer course of
isonazid and rifmapin.
A 10-year study of 283 cases of spinal tuberculosis in
children in Korea showed that antituberculous chemo-
therapy resulted in satisfactory outcome in 88 percent of
the patients (413). There was no benefit from i1n1nobili—
zation either by bed rest or use of plaster of Paris jacket.
Intraspimzl Tuberculosis
Intramedullary spinal tuberculomas occur much less
frequently than cerebral tuberculosis (205,206,403). Al-
though sorne intramedullary tuberculomas are primary,
others occur in association with cerebral tuberculomas.
In addition to paraplegia resulting from the direct effects
of infection, tuberculous arachnoiditis and associated
vasculitis also may produce neurological sequelae. Das-
tur reported that three of six patients in whom spinal
tuberculomas were excised made good neurological re-
coveries (206).
Tuberculosis of the coverings of the spinal cord in-
clude arachnoiditis, subdural granulomas, and extra-
dural granulomas. Tuberculous arachnoiditis is seen in
patients who, in the past, suffered from tuberculous 1nen—
ingitis or pulmonary tuberculosis. Thick, densely orga-
nized exudates may encase the entire length of the spinal
cord and may cause arteritis and secondary vascular
changes leading to "transverse myelitis" or motor loss.
Excision of local arachnoidal granulomas may provide
some relief (201).
Subdural tuberculous granulomas are generally dif-
fuse; the dura is thickened diffusely, and the granuloma
CNS INFECTIONS / 211
surrounds the spinal cord. Some authors prefer to relieve
the compression surgically, but others recommend ste-
roids and antituberculous drugs.
Occasionally, tuberculous epidural granulomas corn-
press the spinal cord but are unassociated with any bony
changes. Lacking the usual bone changes associated with
tuberculosis, such patients may be misdiagnosed and
therefore mismanaged. Myelograms demonstrate a
block. These epidural granulomas (tuberculomas) are
dorsally placed, and, again, laminectomy and antituber-
culous drugs are indicated (410).
Kaufman, Kaplan, and Litman reported seven cases
of tuberculous spinal epidural abscess (412). These pa-
tients had back pain for an average of about three
months. No patient had leukocytosis, and only one had a
fever greater than 100°F. Tuberculous skin tests were
positive in only five of the seven. All showed disc space
or vertebral body involvement, or both. The spinal ab-
scesses contained fibrous granulornas with caseation ne-
crosis. Five of the seven patients demonstrated acid—fast
bacilli on stain and grew out Mycobacteriiim tuberculo-
sis. All seven underwent surgery; three died in the postop-
erative period.
Parasitic Spinal Infection
Spinal Echinococcosis
Hydatid disease caused by Taenia ec/iinococcus rarely
involves the spine. The cchinococcal embryo is carried
to a vertebral body, infiltrates, and destroys bone (414).
Thoracic and lumbosacral vertebrae are most corn-
monly involved. The parasite incites little defensive tis-
sue reaction, and adjacent bones, such as the ribs or pel-
vis, can be invaded. The intervertebral disc is preserved.
Spinal cord impingement occurs as the unencapsulated
parasite invades the spinal canal or as collapsed bone
compresses the cord. Clinical progression of the disease
is slow because the parasite enlarges slowly. The corn-
mon signs and symptoms are pain, motor and sensory
deficits, difficulty with bowel and bladder function, par-
avertebral swelling, and gibbus formation; paraplegia
may occur. CT scanning shows bony destruction, extra-
dural isodense mass, and paraspinal extension of the dis-
ease (415).
Spinal decompression by an anterior (416) or poste-
rior larninectorny approach (417) is carried out, depend-
ing upon location of the neural compression within the
spinal canal. Pathologically, the cyst fluid contains the
typical hooklet—bearing scohces, and the cyst wall is corn-
posed of layers of chitin typical of echinococcosis. Irriga-
tion of the wound with hypertonic saline for five minutes
may help destroy the residual organisms. Occasionally,
total vertebrectomy is necessaiy. Mebendazole has been
used in conjunction with surgery in the treatment of spi-
nal hydatid disease (418). Postoperative use of rnebenda—
zole has been reported as being effective (417).

212 / CHAPTER 10
Spinal Schistosomiasis
The infestation can occur as a space—occupying, intra-
medullary mass, which can extend to involve the cauda
equina (283). It may present clinically as an acute trans-
verse rnyelitis, causing destruction and atrophy of the
cord, or as a progressive neurological process with slow
progressive flaccid paralysis. Males are predominantly
affected. In endemic areas, spinal schistosomiasis is con-
sidered in any patients presenting with spinal cord symp-
toms. Treatment consists of decompressive spinal sur-
gery and schistosomicidal drugs, which kill the adult
female worms and diminish the inflammatory response.
Praziquantel and oxaminquine are the current drugs of
choice; they are administered orally and are relatively
safe (419).
Spinal Cysticercosis
Spinal cysticercosis (420,421) resulting from infesta-
tion with the pork tapeworm occurs in only 2 to 5 per-
cent of all cases of neurocysticercosis. Although this
form of the disease can occur independently of brain
involvement, it usually results from downward spread of
intracranial parasites. The cysts may be intramedullary
or subdural. Associated arachnoiditis is common. Spinal
involvement, though rare, can result in vertebral col-
lapse and spinal cord compression (422).
Guinea Worm (Dracunculus)
Infection with the worm Dracancnlas medinemis is
endemic in Africa and Asia. Rarely, this worm may
lodge in the vertebral extradural space, causing paraple-
gia. The associated inflammatory process is of a low-
grade, chronic nature, but the onset of neurological
symptoms may be sudden and abrupt. Preoperatively,
diagnosis is rarely made because the clinical course is
indistinguishable from many other extradural spinal in-
fections. Known prior guinea worrn infection, periph-
eral blood eosinophilia, and extraspinal calcined lesions
indicating the dead guinea worm may aid diagnosis
(423). The infecting worm causes spinal cord signs, and
myelography reveals a block. The worm is discovered in
chronic granulation tissue and pus at laminectomy.
About half of the patients who are operated on improve.
Niridazole, speciﬁc for guinea worm, has been recorn—
mended (424).
Fungal Spinal Infection
Spinal Blastomycosis
Spinal blastornycosis mainly affects the thoracic and
lumbar vertebrae. Clinically and radiologically, blasto—
rnycosis may be confused with tuberculosis, and the two
diseases may coexist. Accurate tissue or culture diagnosis
of the lesion must be made for appropriate treatment
with amphotericin B.
Candida
Fungal infection of the spine with Candida, although
rare, tends to occur in patients after prolonged hospital-
ization for complex medical problems. Broad spectrum
antibiotics and parenteral hyperalimentation have been
reported as predisposing factors of Candida infection in
general (425). Amphotericin B is effective for treatment
of Candida vertebral osteomyelitis (426). Surgical de-
compression is carried out when there is evidence of spi-
nal cord compression (427).
Spinal Nocardiosis
Rarely, Nocardia, a gram—positive bacteria, spreads he-
matogenously from the lungs to the vertebral bodies and
epidural space and may result in spinal cord involve-
ment. Spinal nocardiosis is treated as any focal spinal
infection. A bacteriological specimen must be obtained
for diagnosis. Surgical decompression by an anterior or
posterior approach depends on the site of the infection in
the spinal canal.
CONCLUSION
The essential ingredient in management of focal CNS
infection is neither medical nor surgical, but rather a
combination of antimicrobial administration and ju-
dicious surgical intervention. Advances in spinal surgery
enable multiple approaches to the spine that facilitate
precise decompression as well as fusion where necessary.
The antimicrobial aspects—with the multiplicity of fac-
tors of organism identification, antimicrobial susceptibil-
ity, and host resistance—afford wide latitude in selection
of an antimicrobial regimen. Further improvement in
therapeutic outcome can be anticipated by meticulous
bacteriological processing and by the application of ex-
isting knowledge of antimicrobial therapy.
Many of the conditions involving infection of the ner-
vous system have associated systemic manifestations.
Consequently, management of patients with these dis-
orders is best achieved through a multidisciplinary team
effort. This is particularly exemplified by AIDS, which
consists of a broad spectrum of disorders, so that team
management is essential.
ACKNOWLEDGMENTS
This Chapter is a revision of previous publications by
the authors, particularly references 428 through 431.
The assistance of Mary F. Boylan, B.A., and Daniel 0.

Walsh, B.A., Researchﬂiditorial Assistants in the Depart-
ment of Neurosurgery, Hahnemann University, in the
preparation of the manuscript is gratefully acknowl-
edged. John Molavi, M.D., Chairman of the Division of
Infectious Diseases, Hahnemann University Hospital,
reviewed those aspects of the manuscript relating to anti-
nncrobialtherapy.
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CHAPTER 11
Princgvles 0fNeur0surgery,
edite by RobertG. Grossman. Rosenberg © 1991'
Published by Raven Press, Ltd., New York.
Trigeminal and Glossopharyngeal Neuralgia
and Hemifacial Spasm
Ronald I. Apfelbaum
Trigeininal and Glossopharyngeal Neuralgia, 223
Incidence, 223
Etiology and Pathology, 223
Symptoms, 224
Signs, 225
Diagnostic Tests, 225
Treatment, 226
Outcome, 231
Heinifacial Spasin, 231
TRIGEMINAL AND
GLOSSOPHARYNGEAL NEURALGIA
Incidence
The true incidence of trigeminal neuralgia is not known,
but it has been estimated from some limited epidemio-
logic studies that approximately 5,000 to 10,000 new
cases occur annually in the United States (1). Women
are more commonly afflicted than men, by a margin of
approximately three to two. Glossopharyngeal neuralgia
is much less common, occurring only once for every 70
to 100 cases of trigeminal neuralgia (2).
Etiology and Pathology
Ancient medical writings describe variations in head
and face pain that probably included cases of trigeminal
neuralgia. The first full description of this condition by a
physician is attributed to John Locke in 1677. Nicholas
Andre is credited with recognition of trigeminal neural-
gia as a definite clinical entity in 1756; in 1773 John
Fothergill published a similar account, unaware of the
R. I. Apfelbaum: Division of Neurological Surgery, The Uni-
versity of Utah, School of Medicine, Salt Lake City, Utah
84132.
223
Incidence, 231
Etiology and Pathology, 231
Symptoms, 232
Signs, 232
Diagnostic Tests, 232
Treatment, 233
Outcome, 233
References, 234
French physician's earlier contribution (3). From these
beginnings, gradually increasing recognition of trigemi—
nal neuralgia ensued. Because the condition presents as a
well—defined clinical entity and because patients afflicted
with this condition suffer so greatly, a great deal of atten-
tion has been focused on studying the problem and at-
tempting to treat it.
Glossopharyngeal neuralgia, on the other hand, is a
much less common problem and has been recognized
only fairly recently as a distinct clinical entity. Weisen—
berg in 1910 first reported this symptom complex in a
patient with a tumor in the cerebellopontine angle; a
report by Sicard and Robineau in 1920 followed. Harris
first used the term glossopharyngeal neuralgia in 1921.
White and Sweet called attention to the involvement of
some of the vagal fibers and suggested the term vag0gl0s-
sop/"Laryngeal neuralgia in 1969 (2). Though technically
more precise, this term has not gained widespread use.
In attempting to explain the etiology and pathophysiol—
ogy of these conditions, various authors have hypothe-
sized about the possible roles of trauma, dental pathol-
ogy and suppuration, clinical and subclinical viral
infections, congenital and acquired skull base distor-
tions, demyelinating processes, neoplasms, vascular
compressive lesions, and intrinsic brainstem pathway
dysfunction. Many theories have been advanced and
have enjoyed brief popularity before falling by the way-
side. Thus, for example, when studies demonstrated a.

224 / CHAPTER 11
frequent occurrence of herpes virus within the gasserian
ganglion, the virus was advocated as the etiologic agent
of trigeminal neuralgia—until control studies demon-
strated an equally high incidence in asymptomatic indi-
viduals.
The one consistent observation, which holds true both
for patients with demyelinating disease and for those
without, is that there are segmental pathological changes
at the root entry zone of the nerve affecting the centrally
myelinated portion of the nerve (4-7). Central myelin
(derived from oligodendroglial cells) extends a few milli-
meters from the brainstem into the nerve before being
replaced by myelin formed by Schwann cells (8). In elec-
tron—microscopic studies there has been consistent de-
myelination in this area, as well as axonal disruption. In
patients suffering from multiple sclerosis who also have
trigeminal neuralgia, demyelinating plaques are invari-
ably located in this region (and may also be found in
other portions of the trigeminal pathway within the
brainstem).
Walter Dandy first observed the high incidence of vas-
cular channels impinging upon the root entry zone of the
nerve and suggested that this might be the cause of tri-
geminal neuralgia (9). It was not until Dr. Peter Jannetta
applied the operating microscope to the systematic study
of these problems that the truly high incidence of such
root entry zone compression was accurately appreciated
(over 97 percent) (10,11). Several postmortem studies
have confirmed the abnormally high incidence of vascu-
lar lesions in patients suffering from trigeminal neuralgia
as compared to control populations (12-14). This com-
pression appears to be the cause of the demyelination
and is accepted by most, but not all, specialists in this
field as the cause of the symptoms in most patients. The
major exception is in patients with multiple sclerosis,
who of course have intrinsic neural disease.
The anatomical derangement in the nerve apparently
alters the physiology in an as yet incompletely under-
stood manner. Gardner has hypothesized the develop-
ment of a "short circuit" in the nerve at the site of de-
myelination, resulting in touch sensation carried by the
larger afferent ﬁbers actuating thinner pain fibers (15).
Loeser, Calvin, and Howe have suggested that antidro—
mic reﬂectance of a normal nerve impulse sets up a re-
verberating circuit, explaining how a light touch can trig-
ger a painful paroxysm (16,17).
Because of its rarity, similar pathological studies have
not been performed in patients with glossopharyngeal
neuralgia, but the conditions are otherwise analogous
and are thought to have the same physiological basis.
Symptoms
These conditions are characterized by a very consis-
tent clinical pattern among patients. Patients will experi-
ence brief repetitive paroxysmal spasms of unilateral
pain of extreme intensity, confined entirely to the terri-
tory of one or more divisions of the trigeminal or the
glossopharyngeal nerve. The pain is frequently described
as a "bolt of lightening" or an electric shock—like phe-
nomenon, and patients will often, in describing the pain,
make a characteristic gesture, ﬂinging open a closed
hand to demonstrate the rapid onset and spread of the
pain.
The pain may occur spontaneously but is often trig-
gered by nonpainful tactile stimuli, usually, but not in-
variably, within the territory of the affected nerve. Thus,
in the case of trigeminal neuralgia, the pain may be acti-
vated by a breeze on the face, touching the face lightly,
chewing, talking, or eating. Common activities, such as
face washing, hair combing, and tooth brushing, become
difficult or impossible. The attack of pain is always uni-
lateral, with an approximately 60 to 40 right to left pre-
dominance. Some patients may be unfortunate enough
to suffer from this condition bilaterally (1 to 3 percent),
but the pain is neither simultaneous nor synchronous on
the two sides.
Most patients will not have any underlying back-
ground pain. But an occasional patient may complain of
a burning or drawing feeling after the sharp paroxysm
subsides, and some will note a prickling, burning or
throbbing sensation before the tic starts (18). In obtain-
ing a history, one must also be careful that repetitive
paroxysms occurring in long volleys are not mistaken for
one steady, long pain.
When the diagnosis is doubtful (usually because the
patient is a poor historian) one should inquire about the
patient's behavior during the pain attacks. Patients with
trigeminal neuralgia tend to remain as immobile as possi-
ble and to guard against any contact with the exposed
area. This is in contradistinction to other types of pain
such as cluster headache (Horton's cephalgia), in which
patients tend to pace or throw themselves about, often
crying out. These latter patients may often place hot or
cold compresses on the face or massage the affected area
in an attempt to diminish the pain.
Both trigeminal and glossopharyngeal neuralgia are
conditions that seem to occur with increasing frequency
with advancing age. Contrary to some descriptions, how-
ever, they are not exclusively diseases of elderly patients
and may occur as early as the teenage years in rare in-
stances. The peak age of onset is in midlife, during the
fifth to sixth decades.
In the natural history of trigeminal neuralgia, rernis—
sions are common and may last for extended periods of
time. With increased duration of the illness, however,
remissions tend to become shorter and periods ofexacer—
bation longer.
Another useful characteristic in the differential diag-
nosis is the infrequent occurrence of nocturnal pain.
Many patients are able to find a comfortable position

TRIGEMINAL AND GLOSSOPHARYNGEAL NEURALGIA AND HEMIFACIAL SPASM / 225
and get adequate rest. This condition therefore is not a
chronic pain but rather an acute pain syndrome occur-
ring repetitively. Narcotic analgesics are impotent in this
situation, and thus it is extremely uncommon to find a
patient who is habituated or even a frequent user of nar-
cotics.
There is a well—established association between trigemi-
nal neuralgia and multiple sclerosis. In a large series of
patients with multiple sclerosis, l to 2 percent will be
found to have trigeminal neuralgia (19). Conversely, a
similar percentage of patients suffering from trigeminal
neuralgia will be found to have multiple sclerosis. As
previously mentioned, in these patients there is a demye—
linating plaque at the root entry zone of the trigeminal
nerve. The site of pathology, therefore, is in exactly the
same area as that found in trigeminal neuralgia pro-
duced by vascular compression, but in these patients the
disease is intrinsic within the nerve rather than due to an
extrinsic cause. The clinical symptoms are also identical.
The association of glossopharyngeal neuralgia and multi-
ple sclerosis has been documented only rarely.
The symptoms of glossopharyngeal neuralgia are gen-
erally similar to those of trigeminal neuralgia but have
some additional features. The pain resembles that of tri-
geminal neuralgia and occurs as brief paroxysms in the
throat or ear. A higher number of patients, however, ex-
perience a dull, aching, or burning feeling. As in trigemi-
nal neuralgia, the episodes of pain are usually triggered,
the common provocative maneuvers being swallowing,
chewing, coughing, or talking. Patients may experience
paroxysms of coughing with their attacks of pain. Syn-
cope has also been reported, but appears to be a very
uncommon associated symptom. It may be due to hyper-
sensitivity of the carotid sinus nerve, producing asystole.
Signs
The diagnosis of trigeminal neuralgia is made by his-
tory. On very close examination with careful attention
being directed to facial cutaneous sensibility, abnormali-
ties may be encountered in as many as 25 percent of
patients; these are minimal changes, which will not nor-
mally be detected on routing neurologic examination.
Of course, if the patient has had prior destructive sur-
gery, appropriate abnormalities may exist.
Tumors in the cerebellopontine angle, which may be a
cause of trigeminal or glossopharyngeal neuralgia, may
produce deﬁcits in several of the lower cranial nerves,
cerebellar dysfunction, and papilledema. These signs
may be detected on a careful neurologic examination.
Diagnostic Tests
There is no speciﬁc test that will establish the diagnosis
of tri geminal neuralgia. The diagnosis rests entirely upon
a careful and adequate history. A magnetic resonance
imaging (MRI) scan should be performed, with particu-
lar attention paid to the affected nerve in the middle and
posterior fossa, on every patient who has this problem so
as to exclude an underlying neoplasm. Multiple sclerosis
will usually be readily detected on the MRI scan, but if
doubt exists other appropriate tests may include audi-
tory and visual evoked responses and spinal ﬂuid analy-
sis to help establish the diagnosis.
In addition to excluding neoplasms and ruling out
multiple sclerosis, MRI scanning in trigeminal neuralgia
has demonstrated the ﬂow voids of vascular loops adja-
cent to the root entry zone of the affected nerve, with
distortion of the nerve. Abnormal uptake of gadolinium
in the compressed region also may be seen. These
changes in the preganglionic segment of the trigeminal
nerve are best viewed on coronal T,—weighted sequences
(Fig. 1) (20). Scanning also alerts the surgeon to the pres-
ence of dolichoectatic major vessels (Fig. 2), aneurysms,
and vascular malformations. All are infrequent causes of
vascular compression but ones that may require differ-
ent treatment or surgical strategies.
In glossopharyngeal neuralgia, in addition to the
above, a useful diagnostic test is the application of a topi-
cal solution of 10 percent cocaine to the oropharynx.
This will provide several hours of relief, during which the
majority of patients with this problem will be able to eat
and drink without experiencing pain. This time helps to
establish the diagnosis and also aids in predicting the
outcome of surgical treatment.
FIG. 1. Coronal T1 —weighted MRI demonstrating two flow
voids (arrows) adjacent to and distorting the right pregan-
glionic segment of the trigeminal nen/e. Note the normal ap-
pearing left preganglionic segment of trigeminal nerve (arrow
head) for comparison.

226 / CHAPTER 11
FIG 2 Coronal T1 -weighted MRI clnuaﬂtg alarge, do-
lichoectatic basilar artery (winte arrows) compressing and
distorting the preganglionic segment of the left trigeminal
nerve (smaller black arrow).
Treatment
The goal of any treatment is to render the patient pain
free at a tolerable level of side effects. The treatment
must provide reliable and consistent pain control so that
not only is the pain relieved but also the fear ofpain
recurrence, which can dominate a patient's life. Partial
control is not a satisfactory goal in this day and age.
T rigeminal Neuralgia: Medical
The management of trigeminal neuralgia (2l,22) is
ﬁrst and foremost medical, with surgical treatment re-
served for those patients who are refractory to medical
treatment or who develop toxicity. Two diugs, pheny-
toin (Dilantin®) and carbamazepine (Tegretol®), are the
mainstays of treatment (23). Many physicians prefer to
start with phenytoin because of its lower toxicity, al-
though it is effective only in about one-half of patients
and has a relatively high failure rate after a period of
time. After an appropriate loading dose, 300 to 400 mg a
day will usually be adequate if this diug is effective.
Seium phenytoin levels can be determined and dosage
adjusted to obtain a therapeutic level of 10 to 20 meg/ml.
We usually start with carbamazepine 100 mg twice a
day and increase it by 100 mg every other day until con-
trol is achieved or toxicity develops. Unlike phenytoin,
this diug has no absolute dosage range. Although some
atients may achieve control with as little as 200 mg a
day, many patients will require 1,600 mg or more. An
average dose might be 800 mg per day (200 mg q.i.d.).
This medication should be given with food or milk to
avoid gastric upset. Common subjective side effects in-
clude mental obtundation, sedation, interference with
higher cognitive functions, disequilibrium, and incoordi-
nation. These are usually dose related. Significant liver,
renal, and especially hematologic side effects also occur.
Patients should therefore have periodic blood tests, ini-
tially every two weeks and then at monthly intervals
while on the medication. The development of toxicity
may limit the use of this diug, but it is initially effective
in over 80 percent of the patients treated. Because carba-
mazepine is so effective, the patient's failure to respond
when an adequate dosage can be tolerated should alert
one to reassess the diagnosis.
Phenytoin may be added to carbamazepine and may
increase the effectiveness of the latter or allow good pain
control at a lower dose, reducing side effects. It, of
course, may be used alone in case ofcarbamazepine intol-
erance or toxicity. Liver function abnormalities, a cuta-
neous rash, disequilibrium, and sedation are some of the
more common side effects and may require discontinu-
ance of the dmg.
Baclofen (Lioresal®) and chlorphenesin carbamate
(Maolate®) are second—order diugs that may help some
patients. In our experience they are most useful for pa-
tients who are well controlled on carbamazepine or
phenytoin but who have to stop using these medications
due to toxicity. They rarely provide significant pain con-
trol for any length of time in patients who do not re-
spond to phenytoin or carbamazepine.
T rigeminal Neuralgia: Surgical
Two types of surgical procedures, percutaneouspurtiul
destruction of the trigeminal preganglionic rootlets and
the Jannetta microvascular decompression of the trigemi-
nal nerve via a posterior fossa craniectomy, are the
current operative procedures of choice for patients who
have become refractory or have developed toxicity to
medical therapy.
Percutaneous neurolysis may be accomplished in sev-
eral ways. These techniques have replaced peripheral
nerve sections or injections, and intracranial sections,
because a more controlled selective partial destiuction of
the nerve can be produced. This achieves pain control
with some preservation of sensation and provides better
long—term results with less risk.
Percutaneous radiofrequency thermal lesioning of the
trigeminal nerve was introduced by Sweet and Wepsic in
1974 (24) as a refinement of earlier gloss electrocoagula—
tion techniques of the gasserian ganglion pioneered by
Kirschner in 1931. Radiofrequency lesioning requires
only a brief hospitalization.

TRIGEMINAL AND GLOSSOPHARYNGEAL NEURALGIA AND HEMIFACIAL SPASM / 227
The procedure can be performed in the x—ray depart-
ment or in an operating theater. Neuroleptic analgesia is
utilized. The patient is sedated with droperidol 150 mg
per kg IM, and fentanyl 50 mg is given intravenously
initially. Supplemental increments of 25 mg of fentanyl
are given as needed, titrating the patient's perception of
pain against the patient's mental state to avoid obtunda—
tion. Fentanyl is a short—acting agent that facilitates good
control of the patient's discomfort, while allowing the
patient to cooperate during the procedure. Such coopera-
tion is essential for proper and safe performance of this
procedure. Some surgeons supplement the above by in-
ducing brief deeper anesthesia with methohexital (Brevi—
tal®) during the more painful moments of the procedure.
A needle electrode is inserted in the cheek approxi-
mately 2 cm lateral to the corner of the mouth and
through the foramen ovale under radiographic control,
utilizing the Hartel technique (Fig. 3) (25). Once the nee-
dle is in place, the stylet is withdrawn and an electrode is
inserted through the needle. Stimulation is then used to
localize the appropriate divisions of the trigeminal
nerve, adjusting the electrode's position as necessary.
Proper localization is achieved when the patient per-
ceives a nonpainful vibratory or paresthetic sensation in
the appropriate division at a threshold of under 0.4 volts
(50 Hz, 2.5 msec continuous pulse train). The radiofre—
quency current is then placed on the electrode, which
raises the temperature of the electrode tip, producing
some thermocoagulation of the preganglionic trigeminal
nerve fibers. After each incremental lesion, the patient is
FIG. 3. Placement of the needle through the lateral cheek
and into the gasserian ganglion for percutaneous radiofre—
quency Iesioning. (From reference 51 , with permission.)
tested and the procedure is terminated when moderate
or greater hypalgesia in the affected area is achieved.
Using carefully applied, small, graded increments of
heating, one can usually remove pain perception while
preserving some useful touch in the treated area, since
the thin unmyelinated pain fibers are more sensitive to
thermal destruction than the larger myelinated touch
fibers. At times the lesion will spread to adjacent divi-
sions of the nerve, producing a larger area of numbness
than desired.
This procedure can be well tolerated even by elderly or
medically debilitated patients. Patients must be aware
that this procedure will permanently alter facial sensa-
tion, producing significant numbness in 90 percent of
our patients, and that it may produce corneal anesthesia
if the ﬁrst division is affected or the lesion spreads to
involve that division. Most patients are willing to accept
this small risk (18 percent experience decreased or ab-
sent corneal sensation; 2 percent corneal ulceration or
keratitis)’l‘ and can tolerate the numbness fairly Well. An
occasional patient, however, will be greatly bothered by
the numbness. If there is any doubt as to a patient's abil-
ity to tolerate numbness, nerve blocks can be performed
to remove sensation temporarily so as to allow the pa-
tient to experience this numbness prior to deciding
whether or not to accept the procedure. I have found it
helpful to describe the altered facial sensation to the pa-
tient as similar to the feeling when a dental anesthetic
has partially worn off. The patient must be aware, how-
ever, that, unlike a dental anesthetic, this sensation will
be a permanent one and cannot be reversed.
More troublesome is the occurrence of dysesthetic
sensations (20 percent), which usually are fairly mild and
well tolerated but in a small percentage (4 percent) can
be quite severe and troublesome. These latter patients,
who suffer from analgesia or anesthesia dolorosa, are
bothered by constant and severe burning, itching, or
crawling sensations, which they may find as intolerable
as their initial trigeminal neuralgia pain. Unfortunately,
these sensations are refractory to treatment, although
some patients will respond to a combination of Trila-
fon 4 mg and amitriptyline hydrochloride (Elavil®) 25
mg q.i.d.
Some authors with greater experience have advocated
making less dense lesions to produce mild to moderate
rather than dense analgesia. This procedure, they claim,
is equally effective in relieving the pain but significantly
decreases the risks of corneal anesthesia and dysesthetic
sequelae (31).
Other unwanted side effects that have been reported
include the rare occurrence of intracranial infections and
* The percentages expressed here represent my personal experience
with 134 patients treated over 10 years by this technique. On analysis,
these percentages agree with many large published series (26-30).

228 / CHAPTER 11
abscesses, and injury to the third, fourth, and sixth cra-
nial nerves. Punctures of the carotid artery and Cavern-
ous sinus usually are benign, but on occasion carotid
cavernous fistula and/or cerebral vascular accidents
have been reported. These latter complications, how-
ever, are all exceedingly rare.
Patients may resume full activity and diet immedi-
ately after recovery from the anesthetic and are usually
discharged the following day. There are no restrictions of
their activities after this procedure.
Percutaneous Chemoneurolysis with glycerol was intro-
duced in 1981 by Hakanson (32). In this approach, pure
anhydrous glycerol (99.5 percent) is instilled into the tri-
geminal cistern under ﬂuoroscopic control. It is not clear
whether the effect of the glycerol is due to chemical or
hyperosmotic damage to the trigeminal nerve pregan—
glionic rootlets. In any case, the effect is to produce ex-
cellent pain relief with usually only minimal sensory loss
at times none. Some patients, however, will get
significant sensory loss (4 percent), even anesthesia,
though the latter usually occurs only with sequential de-
stiuctive procedures. In 158 patients treated with this
technique over seven years, we have only rarely observed
corneal anesthesia (4 percent) and have never seen kera-
titis develop as a sequela to the procedure. Dysesthetic
sensations are also very infrequent (3 percent) and
usually quite mild. Anesthesia dolorosa has not been re-
ported from this procedure (33).
We perform the procedure in the x—ray suite, using the
same technique for puncturing the foramen ovale under
direct ﬂuoroscopic guidance that we use for radiofre—
quency lesioning (25). The entry site, approximately 2 to
3 cm from the comer of the mouth, is selected ﬂuoro-
scopically (Fig. 4A) by placing the patient with his neck
FIG. 4. Fiuoroscopic images during glycerol chemo-
neurolysis for trigeminal neuralgia. (A) lnitial scout view
showing paper clip on skin at entrance site and end—on
view of foramen ovale. (B) Needle has now been in-
serted into the medial end of the foramen ovale, under
direct fluoroscopic imaging. (C) Trigeminal cisterno-
gram, AP projection with patient in upright position.
Preganglionic rootlets are visible as linear filling defects
within the cistern.

TRIGEMINAL AND GLOSSOPHARYNGEAL NEURALGIA AND HEMIFACIAL SPASM / 229
hyperextended and head rotated to the contralateral side
about 15 to 20 degrees. This allows visualization directly
along the needle pathway, with the foramen ovale seen
projecting over the petrous ridge.
Needle puncture and advancement through the fora-
men ovale is accomplished with the patient brieﬂy anes-
thetized using 40 to 60 mg of methohexital. It is impor-
tant that the foramen ovale be punctured at its medial
end to properly engage the trigeminal cistern. This can
be reliably accomplished using the ﬂuoroscopic tech-
nique described above and placing the needle through
the foramen as its progress is being monitored G3ig. 4B).
Once the needle is in place and a free ﬂow of cerebro—
spinal ﬂuid (CSF) is obtained, the patient is allowed to
awaken. A cisternogram is then performed by connect-
ing a J ml syringe and extension tubing filled with io-
hexol (Omnipaque®, Winthrop Pharmaceuticals, New
York) (350 mg% concentration) to the needle, tilting the
x—ray table to the vertical position, and slowly injecting
the contrast agent while ﬂuoroscoping in the anteroposte—
rior (AP) projection. If the needle is properly placed, the
contrast will fill the small cup—shaped trigeminal cistem
(Fig. 4C), then overﬂow into the posterior fossa. The
cisternogram confirms the correct placement and also
allows quantification of the size of the trigeminal cistern.
If not in the cistem (for example. CSF can be obtained in
the subarachnoid space beneath the temporal lobe), the
needle must be repositioned.
After satisfactory placement and cisternogram, the pa-
tient is again placed recumbent to allow the contrast
agent to ﬂow out of the cistern; this is confirmed ﬂuoro-
scopically. The patient then is placed back on a stretcher
in a full upright sitting position, and a quantity of glyc-
erol equal to the volume of the cistern is instilled slowly.
This may produce trigeminal pain, so it is best to pre-
rnedicate with analgesics, such as fentanyl, first. The pa-
tient is then transported back to his or her room but kept
sitting up at all times for about two hours to keep the
glycerol in the trigeminal cistern.
Most patients are pain free within a few hours and
may be discharged the following morning. Some will
continue to have tic pain for 7 to 10 days, though usually
it is distinctly less. Ten percent will require a second
procedure to get full relief. Once relieved. 75 percent
were still pain free after three years. For those with recur-
rence, the procedure can be readily repeated and has
been tolerated well so that there usually is no reluctance
on the patient's part to accept a repetition (unlike radio-
frequency lesioning).
Perciitaneoits Compression of the gasserian ganglion
with a balloon catheter was introduced by Mullan in
1983 as technique to traumatize the trigeminal ganglion
and preganglionic rootlets mechanically using a percuta-
neously inserted balloon—tipped catheter (34). The cath-
eter is placed through the foramen ovale, using a similar
approach to the above two techniques, and then inﬂated
to compress the neural structures. The technique is
based on the earlier observation of Taarnhoj that me-
chanical trauma could relieve the pain of trigeminal neu-
ralgia, often for a significant period of time (35).
While long—term follow—up is not yet available, the ini-
tial results of this procedure appear to be comparable to
glycerol chemoneurolysis, with significantly less anesthe-
sia, dysesthesia, and corneal anesthesia than following
radiofrequency lesioning.
The Jannetta microvasciilar decompressive procedure,
in contradistinction to percutaneous neurolysis, in-
volves a formal operative procedure under general anes-
thesia. As such, it will always carry with it a higher risk. It
offers, however, the significant benefit of treating what
appears to be the probable cause of this problem and
achieving reliefwithoat neural destruction. Patients who
undergo this procedure, therefore, must accept a slightly
higher risk of serious complications but may be "cured"
of their problem without sacrificing neural function. We
usually reserve this procedure for the younger patient
(under 65) who is in good health and who is willing to
accept the somewhat higher risk to achieve these goals.
The procedure involves a limited suboccipital retro-
mastoid craniectomy performed under general endotra—
cheal anesthesia (35). I and many other surgeons have
preferentially used a sitting position for this operation;
however, equally satisfactory results can be achieved uti-
lizing a lateral, recumbent, or prone position. Access to
the trigeminal nerve is achieved by placing the craniec-
tomy just below the transverse sinus and just medial to
the sigmoid sinus. Opening the dura close to these ve-
nous sinuses allows exposure of the cerebellopontine an-
gle along the superior lateral margin of the cerebellum,
which is retracted gently. Prior microsurgical experience
and the use of the operating microscope are mandatory
for safe and accurate dissection. The petrosal vein is
usually coagulated and divided to gain access to the re-
gion of the trigeminal nerve, and the arachnoid around
the nerve is opened widely to inspect this area fully.
Elongated arterial loops impinging upon and cross-
compressing the root entry zone of the trigeminal nerve
are the most common findings in patients undergoing
this operation (Fig. 5A). In our personal series of over
300 cases, these were encountered 79 percent of the time
(36,37). Occasionally, venous channels impinging upon
the nerve in a similar manner were found (15 percent)
and, on rare occasions, tumors in the cerebellopontine
angle, such as meningiomas, acoustic neurinomas, or
cholesteatomas, were seen (3 percent). No pathology was
found in 3 percent of these patients. When tumors are
encountered, they are removed. Veins can be coagulated
and divided to decompress the root entry zone of the
nerve. Arterial channels are dissected completely free of
the root entry zone and secured with a small plastic
sponge prosthesis, usually Ivalon® (Unipoint Industries,
High Point, North Carolina) or a shredded teﬂon sponge

230 CHAPTER 11
FIG. 5. (A) View through the operating microscope of the left trigeminal nerve, compressed by an
elongated superior cerebellar artery (SCA) as it traverses the brainstem. The artery is caught in the axilla
between the nerve and brainstem. (B) View after elevation of the arterial loop and placement of the
plastic prosthesis to prevent the reapposiﬁon of artery and nerve. (From reference 36, with permission.)
(Fig. 5B). The goal is to redirect the arterial pulsation
away from the root entry zone. Our operative findings
fully support those of Jannetta, and our results and fol-
low—up closely agree with those he has reported (38,39).
After satisfactory decompression, the dura is closed in
a watertight fashion and the wound is closed in layers.
We routinely place our patients on steroids preopera-
tively and for 24 hours postoperatively. Most patients
tolerate this procedure well and are able to begin oral
intake and get out of bed on the first postoperative day. If
the patients are operated on in the sitting position, they
usually have a moderate postoperative headache, which
can be controlled with oral analgesics. The majority of
patients can be discharged five to seven days postopera-
tively and usually take another week or two of additional
convalescence at home. During this period, they are en-
couraged to increase their activities gradually.
As with any operation, this procedure is not without
risk and fatal complications have ensued (1 percent).
Cerebellar hematomas or hemorrhagic infarction (1.6
percent) and supratentorial strokes (1 percent) have oc-
curred and at times have been responsible for fatalities,
despite vigorous appropriate treatment. Other signifi-
cant complications have included transient fourth—nerve
palsies (4 percent), transient facial nerve palsies (1.6 per-
cent), and unilateral hearing loss (2 percent; 1 percent
severe).
In trigeminal neuralgia associated with multiple sclero-
sis, if medical treatment is unsuccessful, relief can be
effected only by a destructive procedure. Percutaneous
lesioning is therefore the procedure of choice. If this is
unsuccessful for technical reasons, section ofthe nerve in
the posterior fossa will produce a similar benefit and, if
performed immediately adjacent to the brainstem, pro-
duces a lower incidence of dysesthesia and of numbness
than more peripheral destruction of the nerve.
There is a somewhat higher incidence of bilateral tri-
geminal neuralgia in patients afﬂicted with multiple scle-
rosis than occurs otherwise. In a small percentage ofpa—
tients, trigeminal neuralgia may be the initial presenting
symptom of multiple sclerosis. This may explain the oc-
casional negative posterior fossa exploration, especially
in the younger patients.
Glossopharyngeal Neuralgia
The medical principles of treatment as outlined for
trigeminal neuralgia apply equally to this condition. If
these are unsuccessful, the Jannetta microvascular de-
compression appears to be the definitive procedure of
choice, offering, as with trigeminal neuralgia, the oppor-
tunity for the relief of pain without sacrificing neural
function (38,39).
Radiofrequency lesioning at the jugular foramen has
been attempted, but this only produces a lesion distal to
the ganglion. Thus, recurrences in a few months can be
expected, as with peripheral nerve sectioning.
An alternative procedure involves sectioning of the
glossopharyngeal nerve and the upper several fascicles of
the vagus nerve in the posterior fossa (2). This procedure,
employed since its introduction by Love in 1948, is pref-
erable in more elderly patients, rather than exposing
them to increased operating time and the risks of manip-
ulating their intracranial vessels.
Potential complications and postoperative care are as
described above for trigeminal neuralgia. After section-
ing ofthe nerve, dysphagia may occur, as well as unpleas-
ant pharyngeal sensations.

TRIGEMINAL AND GLOSSOPHARYNGEAL NEURALGIA AND HEMIFACIAL SPASM / 231
Outcome
Success in relieving the pain of trigeminal neuralgia
has been achieved in about 95 percent of the patients
treated with either of these two types of procedures. Re-
currences following percutaneous radiofrequency le-
sioning have varied significantly in different series, but
average approximately 35 percent within four years.
There is an increasing incidence of recurrences with the
passage of time after surgery. Recurrences may occur in
the treated area but are more common in adjacent un-
treated regions. If necessary, the procedure can be re-
peated and many surgeons have preferred to produce
minimal lesions, minimizing numbness and decreasing
the risk of corneal anesthesia and dysesthetic sequelae,
while accepting a higher recurrence rate and repeating
the procedure as often as necessary (27).
With the J annetta microvascular decompression, re-
currences, when they occur, tend to occur early, usually
within the first year to 18 months, with only a rare recur-
rence being reported after that. Severe refractory recur-
rences have occurred in 13 percent of our patients. An
additional 19 percent of our patients have had some
pain, which was well controlled with medication, usually
at very low dosages. Many of these patients (about one-
half) subsequently have been able to discontinue the
medication. All were refractory to medical treatment pre-
operatively, and most have reported that they feel the
procedure was of significant benefit to them, even if they
have required additional medication. Thus the overall
success rate for excellent (painfree) and good (controlled
pain) results is 87 percent.
Both of these procedures, therefore, offer great poten-
tial for the relief of this severe, incapacitating pain. Pa-
tient satisfaction with either has been gratifying, though
patients undergoing microvascular decompression are
significantly happier, since they do not have any sensory
loss, with its annoyance serving as a constant reminder
oftheir problem. The lack of dysesthesia and fewer recur-
rences also contribute to this increased satisfaction.
The choice of procedure must ultimately be made by
the patient, after he or she has achieved a thorough un-
derstanding of the potential risks and benefits of each.
The physician's recommendation also must be based on
a careful analysis of the patient's general health. For the
patient under age 65, in good general health, we usually
recommend the J annetta microvascular decompression.
Glycerol chemoneurolysis is our preferred technique for
those patients who do not meet the above criteria, who
have multiple sclerosis, who do not wish to accept the
risks of microvascular decompression, or who have a re-
current tic after a prior surgical procedure.
The results in glossopharyngeal neuralgia are similar,
in a smaller number of reported cases treated with the
Jannetta procedure, and also with sectioning of the
nerve. The frequency of recurrence after microvascular
decompression approximates that seen in trigeminal neu-
ralgia and is less with nerve sectioning if the upper vagal
rootlets are included.
HEMIFACIAL SPASM
Incidence
Hemifacial spasm is a relatively rare condition. There
are no published epidemiologic studies, so its true inci-
dence is not known. From personal experience I would
estimate this condition to be approximately 25 percent
as common as trigeminal neuralgia. This may not be a
true figure, however, because many individuals may en-
dure rather than seek treatment for this condition, which
is neither life threatening nor painful. Also great regional
variation in incidence occurs, with an especially high fre-
quency of occurrence noted in Oriental (especially J apa-
nese) patients.
Etiology and Pathology
Hemifacial spasm appears to be the direct motor ana-
logue of trigeminal neuralgia. That is, both are disorders
of paroxysmal hyperactivity occurring in a cranial nerve.
Hemifacial spasm involves the facial nerve and as such
manifests pure motor hyperactivity, in comparison with
trigeminal neuralgia, which occurs in a primarily sen-
sory nerve and causes paroxysms of pain.
Significant historical observations have noted that, if
the nerve is sectioned at the stylomastoid foramen and
anastomosed to itself, the spasms return with reinnerva—
tion. If, however, an anastomosis to another cranial
nerve is performed, the spasms do not return. Thus the
site of pathology must be proximal to the stylomastoid
foramen. It has also been observed that a supratentorial
stroke producing a hemiplegia does not relieve the spasm
even in an otherwise plegic face (40). Therefore, the
pathological process must be confined to the lower mo-
tor neuron.
Isolated case reports dating back to an autopsy study
by Schultze in 1875 (41) have demonstrated vascular
lesions compressing the facial nerve in the posterior
fossa. Campbell and Keedy published two cases in 1947
in which a "cirsoid aneurysm" (nowadays known as ver-
tebral basilar dolichoectasia) was found compressing the
facial nerve (42). Other isolated case reports support
these observations. Tumors compressing the facial nerve
in the posterior fossa and causing hemifacial spasm were
noted by Dandy (43,44) and Gushing (45). In 1961
Gardner and Sava presented their experience with 19
patients (46). In 14 of these they found mass lesions. In
the majority of cases, the problem appeared to stem from
either normal or abnormal blood vessels. Gardner and

CHAPTER 11
Sava also suggested that hemifacial spasm was a revers-
ible pathophysiological state.
It was not until the systematic application ofthe oper-
ating microscope by Peter J annetta, commencing in
1967, that a large series of observations was made in
patients with hemifacial spasm. J annetta not only firmly
established that root exit zone compression of the facial
nerve is present in virtually every patient afﬂicted with
this problem but also devised a nondestructive tech-
nique for moving the blood vessel (which is the common
cause) away from the nerve and securing it with a small
sponge prosthesis to decompress the nerve effectively.
J annetta's observations have been substantiated by sev-
eral other surgeons (36,47), firmly establishing the etiol-
ogy of hemifacial spasm.
The exact physiological effect that this root exit zone
compression produces is not fully understood. Hunt in
1909 detailed the role of sensory afferent fibers in the
facial nerve. Gardner suggested a reverberating circuit
produced by afferent—efferent transaxonal "short—circuit—
ing" (46).
Symptoms
Hemifacial spasm usually begins with small, uncon-
trollable twitching movements occurring in a unilateral
orbicularis oculi muscle, with a slow and insidious pro-
gressive spreading of the spasms down the face. The hy-
peractivity is limited entirely to muscles supplied by the
seventh cranial nerve. The twitching is involuntary and
patients are unable to stop it.
The condition tends to worsen gradually with the pas-
sage of time, often slowly over months to years until
gross disfiguration of the face occurs. Far from being
only a cosmetic problem, hemifacial spasm creates signif-
icant functional disability because of the limitations on
vision imposed by the constant blinking and twitching.
This can impair many normal daily activities such as
reading and driving. With increased severity, the pla-
tysma muscle in the anterior neck and the corrugator
muscles of the forehead may ultimately become in-
volved. J armetta and associates have also described an
atypical form of this problem, which starts in the mid-
face and advances up to the forehead (48).
Hemifacial spasm is slightly more common in men
and more common on the left side of the face. It has not
been described in children. Like many neurologic prob-
lems it will be aggravated by psychological stress as well
as fatigue and has therefore been erroneously thought to
have an emotional basis. Voluntary movement may ag-
gravate the spasms. Spasms often stop during sleep but
may persist in about 10 percent of patients. Bilaterality
has been described (6 percent), but, when this occurs, the
spasms are neither synchronous nor symmetrical.
Hemifacial spasm has been reported in association
with trigeminal neuralgia. Gushing apparently was the
first to describe this under the term "tic convulsif" (49).
Most commonly, mass lesions in the posterior fossa, re-
sulting in compression of both the fifth and seventh
nerves, have been associated with this combination. Sep-
arate independent lesions, however, may also occur.
Signs
The clinical appearance of patients suffering from this
problem is quite characteristic. Intermittent, uncontrol-
lable, brief, repetitive, and painless spasms of the facial
musculature, most prominent in the midface, are noted.
Occasionally the "tonus" phenomenon occurs, in which
sustained forceful contractures, usually of the midface
musculature, last for several seconds or even longer.
Physical examination will usually reveal abnormalities
of the cranial nerves. Mild facial paresis (between
spasms) may be noted, as well as mild decreased hearing
in the ipsilateral ear, in long—standing cases. Deﬁcits in
cranial nerves V, VII, or IX or cerebellar or brainstem
findings suggest a mass lesion in the cerebellopontine
angle.
Diagnostic Tests
The diagnosis of hemifacial spasm can be made by the
clinical appearance in association with the history as
given above. There is remarkable consistency among pa-
tients in clinical presentation. On electrical testing, the
EMG in hemifacial spasm is quite characteristic, demon-
strating rhythmically occurring bursts of 5 to 20 dis-
charges per second, along with individual discharges and
longer lasting bursts (50). The rate of discharge of the
latter may be as high as 150 to 250 per second, with
almost complete synchronization ofthe discharges occur-
ring within the entire area of the affected facial muscles.
These electrical findings are not seen in other conditions
and will therefore differentiate hemifacial spasm from
other types of abnormal facial motor activity.
The differential diagnosis of hemifacial spasm in-
cludes blepharospasm, which is a bilateral forced con-
tracture of the muscles about the eyes and is distin-
guished from hemifacial spasm by its bilaterality and its
confinement entirely to the periorbital musculature. Fol-
lowing Bell's palsy, at times, synkinetic movements of
the face may mimic hemifacial spasm. This history of
antecedent Bell's palsy with the development of such
movements as the nerve regenerates usually will distin-
guish these, but electrical testing may be helpful. An-
other condition, facial myokymia, results in writhing
wo1‘m—like movements of the facial musculature. This is
seen with intrinsic brainstem disease and, again, can be
differentiated electrically if the clinical situation is not
clear—cut.

TRIGEMINAL AND GLOSSOPHARYNGEAL NEURALGIA AND HEMIFACIAL SPASM / 233
As in trigeminal neuralgia, a MR scan may disclose a
Vascular loop but mainly is done to rule out a mass le-
sion.
Treatment
There is no effective medical treatment for hemifacial
spasm. This condition has been described as "socially,
psychologically and economically disabling" (48). There-
fore, surgery is of much more than cosmetic significance.
A number of procedures involving methods of destroy-
ing or injuring the facial nerve have been attempted but
result in incomplete relief of the problem and facial palsy
to some extent.
Some success has been achieved with partial denerva—
tion of the facial muscles by injecting botulinum toxin
into the most active regions. With small incremental in-
jections, denervation can be limited and the spasms re-
duced. Denervation of course does not fully resolve the
problem and may require repetitive treatments, but it
can be considered as an alternative, especially in elderly
or infirm patients.
The definitive treatment of this problem is the Jan-
netta microvascular decompressive operation, which in-
volves a limited retromastoid posterior fossa craniec—
tomy and microsurgical exploration of the root exit zone
of the facial nerve. Lesions impressing upon the nerve at
this area have been found in close to 100 percent of pa-
tients in several large seiies explored by this technique
(Fig. 6). Most commonly these are arterial channels, ei-
ther normal vessels (usually the posterior inferior cere-
bellar artery, the anterior inferior cerebellar artery, or the
vertebral artery) or dilated or ectatic vessels (previously
called cirsoid aneurysms), but on occasion venous chan-
nels, arteriovenous malformations, aneurysms, and
small tumors have been encountered. These latter of-
fending causes are surgically removed. Arterial channels
are dissected free of the nerve and secured with a small
plastic sponge prosthesis to prevent their reappostion.
The operative technique is similar to that employed in
the Jannetta operation for trigeminal neuralgia, except
that the exposure is from lateral inferior, beneath the
cerebellum (36,48).
Outcome
The J annetta procedure has resulted in excellent relief
of hemifacial spasm in the vast majority of patients so
treated. J annetta in 1980 reported excellent results in
213 of 229 patients (12 patients required a second proce-
dure) (39). An additional 11 patients (5 percent) had less
than 25 percent of their preoperative level of spasms but
were not completely relieved. The procedure failed in
five patients (2 percent).
FIG. 6. Surgeon‘s view through the operating microscope.
Exposure of left facial nerve. When the cerebellum is ele-
vated, the root exit zone of the facial nerve is seen to be
compressed by an elongated loop of the posterior inferior
cerebellar artery (PICA). (From reference 36, with permis-
sion.)
In our personal seiies of 66 patients, we have found
vessels compressing the nerve in 65 cases: 64 were ane-
rial channels and l was a venous channel. A bony exos—
tosis compressed the nerve in the remaining case. No
negative explorations occurred. All patients were ini-
tially relieved of their spasm, although the spasm did
persist in the postoperative period for up to several
months in 10 percent of these patients before finally sub-
siding. Recurrences have appeared in 16 patients. Nine
were transient and resolved completely, four were mini-
mal not requiring further treatment, and two were signifi-
cant. One of these has been relieved by a second opera-
tion. Facial weakness was noted in six patients but was
only minimal in three. All these patients have recovered
from it.
This procedure, of course, involves a formal craniot—
omy under general anesthesia and will always carry with
it a small but real element of risk. In addition to the
generalized risks detailed earlier regarding this operative
technique for trigeminal neuralgia, the procedure as ap-
plied to the facial nerve carries with it the primary risk of
injury to the facial and/or auditory nerve. Thus, hearing
loss has been reported in the literature in approximately
8 percent of patients and facial weakness in 7 percent. In
our own experience, we have encountered hearing loss in
only one patient (2 percent) and, as noted, no permanent
facial weakness.

CHAPTER 12
Head Injury
Raj K. Narayan
Causes, 236
Classification, 236
By Mechanism, 237
By Severity, 237
By Morphology, 237
Ma11age1ne11t of Head I11 jury, 239
Mild Head Injury, 239
Moderate Head Injury, 240
Severe Head Injury, 241
Surgical Considerations, 258
Anesthesia, 258
Subdural Hematomas, 258
Epidural Hematomas, 258
Intracerebral Hematomas, 259
Posterior Fossa Hematomas, 260
Depressed Fractures, 261
Penetrating Head Injuries, 261
Venous Sinus Injuries, 262
Therapeutic Agents, 262
Anticonvulsants, 262
Steroids, 264
Mannitol, 264
Lasix, 265
Sodium Bicarbonate, 265
Tris—hydroxy—methyl—aminomethane (THAM), 265
Barbiturates, 265
Naloxone, 266
Sho1t—Acting Hypnotics, 266
Hyperbaric Oxygen, 266
Trauma is the leading cause of death in the United States
for persons between 1 and 44 years of age and is the third
most common cause overall (1). In over half of trauma-
related deaths, head injury contributed significantly to
the outcome (2). In patients with multiple injuries, the
head is the most commonly injured part, and in fatal
road accidents, injury to the brain is found in nearly 75
R. K. Narayan: Department of Neurosurgery, Baylor Col-
lege of Medicine, Houston, Texas 77030.
Princi les 0fNeur0surgery,
editedp by Robert G. Grossman. Rosenberg © 1991.
Published by Raven Press, Ltd., New York.
Free Radical Scavengers, 266
I11tracra11ial Pressure Monitoring a11d Control, 266
Basic Physiology, 266
Technical Aspects, 268
Value of ICP Monitoring, 268
Indications for ICP Monitoring, 269
Treating Raised ICP, 269
Complications of ICP Monitoring, 270
Management of Associated I11juries, 270
235
Scalp Injuries, 270
Maxillofacial Injuries, 271
Injuries of the Spine, 273
Orthopedic Injuries, 275
Chest Injuries, 275
Vascular Injuries, 277
Abdominal Injuries, 277
Renal Injuries, 277
Ophthalmological Injuries, 278
Sequelae of Head I11jury, 278
Cranial Nerve Injuries, 279
Locked—in Syndrome, 280
Peripheral Neuropathies, 280
Posttraumatic Hydrocephalus, 281
Cerebrospinal Fluid Fistulas, 282
Posttraumatic Vascular Complications, 283
Prognosis, 285
Conclusion, 285
References, 286
percent of the victims at autopsy (3). In 1982 there were
approximately 165,000 deaths from trauma in the
United States, and for each death there were at least two
cases of permanent disability, usually secondaiy to head
injury (4). Trauma accounts for the loss of more poten-
tial work—life yeais (3.5 million) than cancer (1.8 million)
and cardiovascular disease (1.6 million) combined (5,6).
Because trauma often affects people early in life, its cost
measured in death and disability is veiy high. The total
annual cost of accidental trauma, including lost wages,

236 / CHAPTER 12
medical expenses, and indirect work losses, is estimated
at $75 to 100 billion (7). During the past decade, the
death rates from heart disease and stroke have fallen by
22 percent and 32 percent, respectively, but the death
rate from trauma has risen by approximately 1 percent
each year since 1977 (4).
The incidence of traumatic brain injury in the United
States is conservatively estimated to be approximately
200/ 100,000 (2). With a total population of 235 million
(1984), this translates into approximately 470.000 new
cases per year (2). Of these, 70.000 patients die before
reaching the hospital. The remaining 400,000 are admit-
ted to hospitals. Ofthese. 80 percent (320,000) are catego-
rized as mild, 10 percent (40000) as moderate, and 10
percent (40,000) as severe brain injuries. These figures
do not include the large number of patients with mild
head injuries who are not admitted to a hospital. It is
estimated that the death rates in the mild, moderate, and
severe categories are 0 percent, 7 percent, and 58 per-
cent, respectively, yielding a total annual mortality of
26.000 patients. Together with the prehospital mortality,
head injury thus accounts for approximately 96,000
deaths per year in the United States (2).
Perhaps even more dramatic than the mortality ﬁg-
ures is the magnitude of the population with residual
disabilities. Again, conservatively, with estimations of a
permanent disability rate of 10 percent in the mild, 66
percent in the moderate, and 100 percent in the severely
brain—injured groups, it is calculated that there are
73,724 new patients with long—term residual disabilities
secondary to brain injury being added to the pool each
year. This includes about 2,000 who remain in a perma-
nent vegetative state (8). The total direct and indirect
cost to the nation for persons with disabilities owing to
brain injury is estimated to be around $25 billion per
year and is increasing.
These figures leave no doubt that death and disability
from trauma in general, and head injury in particular, is
a major public health problem in the United States. Any
therapeutic measures that could reduce the mortality
and morbidity associated with these injuries even
slightly could translate into very significant benefits in
both human and economic terms.
CAUSES
Head injury is primarily an afﬂiction of young adults
between 15 and 44 years of age (9). The average age re-
ported in several series is around 30 years. Males are
affected more than twice as often as females. There does
not appear to be any difference in incidence between
whites and nonwhites in the United States.
Motor vehicle accidents are the most frequent cause of
head injury, accounting for about 49 percent of all cases.
Motor vehicle accidents are associated with more severe
head injuries and occur more often in those 15 to 24
years of age, whereas falls occur more often in the pediat-
ric age group and usually result in less severe injuries.
Patients involved in motor vehicle accidents often sus-
tain multiple injuries. In one series of severely head—in—
jured patients, more than 50 percent were found to have
additional major systemic injuries (10). Although the
overall incidence of intracranial hematomas following
head injury is only 2 percent, approximately one—half of
the patients who arrive at the hospital unconscious from
a head injury will have a major intracranial hema-
toma (11).
For head injury there is an early peak in occurrence in
April, followed by a general increase to the highest
monthly percentage in September (9). Most head and
spinal cord injuries occur on Fridays, Saturdays, and
Sundays, times when coverage in hospitals is often less
than optimal. Thus, we are dealing with a very common
problem that tends to occur at inconvenient times, de-
mands a lot oftime and attention, and can lead to disas-
trous results if not handled rapidly and appropriately.
Although a great deal has been learned about central
nervous system trauma, both at a cellular and at a clini-
cal level, much remains controversial. In the following
account we have outlined our approach, trying to indi-
cate controversial aspects whenever they appear. How-
ever, it must be emphasized that the management proto-
cols described here are not entirely based on
incontrovertible scientific data. They are certainly not
the only correct way of managing head injury.
CLASSIFICATION
Head injuries may be classiﬁed in several ways. For
practical purposes, three means of classification are use-
ful—classification by mechanism, severity, and morphol-
ogy (Table 1).
TABLE 1. Classification of head injury
A. By mechanism
1 . Closed
2. Penetrating
B. By severity
1 . Glasgow Coma Scale score
2. Mild, moderate, severe
C. By morphology
1 . Skull fractures
a. Vault
(1) Linear or stellate
(2) Depressed or nondepressed
b. Basilar
2. intracranial lesions
a. Focal
(1) Epidural
(2) Subdural
(3) lntracerebral
(1 ) Mild ooncussion
(2) Classical concussion
(3) Diffuse axonal injury

By Mechanisln
Head injury may be broadly classified as closed or
penetrating. Although these terms are widely used and
are useful from a descriptive point of view, they are not
mutually exclusive. For example, a depresse skull frac-
ture could be variably assigned to either one of these two
categories, depending on the depth and severity of the
bony injury. Nevertheless, for practical purposes, the
term "closed head injury" is usually associated with auto
accidents, falls, and assaults, and "penetrating head in-
jury" is most often associated with gunshot wounds and
stab injuries. Because the management of these two
broad groups is slightly different, we shall maintain this
distinction for descriptive purposes.
By Severity
Prior to 1974, different authors used terminology with
variable connotations to describe patients with head in-
jury, making it virtually impossible to compare groups of
patients from different centers. In 1974 Teasdale and
J ennett, by studying the signs that seemed to predict out-
come most reliably and which seemed to have the least
interobserycr variation, designed what has come to be
known as the Glasgow Coma Scale (GCS). The introduc-
tion of the GCS (Table 2) brought some degree ofunifor—
mity and discipline into the head injury literature (12).
This scale has achieved widespread use for the descrip-
tion of patients with head injury and, furthermore, has
been adopted for the description of patients with altered
levels of consciousness from other causes.
Jennett and Teasdale defined coma as the inability to
obey commands, utter words, or open the eyes (13). The
patient who does not meet all three aspects of this defini-
tion is not considered comatose. In a series with 2,000
TABLE 2. The Glasgow Coma Scale (GCS)a
Eye opening (E)
Spontaneous
To call
To pain
None
Motor response (M)
Obeys commands
Localizes pain
Normal flexion (withdrawal)
Abnormal flexion (decorticate)
Extension (decerebrate)
None (flaccid)
Verbal response (V)
Oriented
Confused conversation
Inappropriate words
lncomprehensible sounds
None
—‘l\)(A3-PU‘! -‘N03-l>U107 —“l\)00-l>
3 GCS sum score = (E + M + V); best possible score =15;
worst possible score = 3
HEAD INJURY / 237
patients with a severe head injury, these authors ob-
served 4 percent who did not speak but obeyed com-
mands and another 4 percent who uttered words but did
not obey. Among patients who could neither obey nor
speak, 16 percent opened their eyes and were therefore
judged not to be in coma. Patients who open their eyes
spontaneously, obey commands, and are oriented score
a total of 15 points, whereas ﬂaccid patients who do not
open their eyes or talk score the minimum of 3 points.
No single score within the range of 3 to 15 forms the
cut—off point for coma. However, 90 percent of all pa-
tients with a sum score of eight or less, and none of those
with a score of nine or more, are found to be in coma
according to the preceding definition. For all practical
purposes, a GCS sum score of eight or less has become
the generally accepted definition of a comatose patient.
The distinction between patients with severe head injury
and those with mild to moderate injury is thus fairly
clear. However, distinguishing between mild and moder-
ate head injury is more of a problem (14). Somewhat
arbitrarily, head—injured patients with a GCS sum score
of 9 to 12 have been categorized as moderate, and those
with a GCS score of 13 to 15 have been designated mild.
Williams, Levin, and Eisenberg have recently reported
that neurobehavioral deficits in patients with mild head
injury (GCS 12 to 15) with an intracranial lesion on ini-
tial computed tomography (CT) were similar to those in
patients with moderate head injury (GCS 9 to 11). Pa-
tients with mild head injury uncomplicated by an intra-
cranial lesion on CT scan did significantly better (15).
By Morphology
The advent ofCT scanning has revolutionized the clas-
sification and management of head injury. Thus, al-
though certain patients who are rapidly deteriorating
may be taken to surgery without a CT scan, the vast
majority of severely injured patients should have the
benefit of a CT scan prior to surgical intervention. Fur-
thermore, frequent follow—up CT scans are essential be-
cause the morphological picture in head injury often un-
dergoes a remarkable evolution over the first few hours,
days, and even weeks after the injury. Morphologically,
head injuries may be broadly considered under two head-
ings: skull fractures and intracranial lesions.
Skull Fractures
Skull fractures may be seen in the cranial vault or skull
base, may be linear or stellate, and may be depressed or
nondepressed. Basal skull fractures are harder to docu-
ment on plain x—rays and usually require CT scanning
with bone—window settings to demonstrate their loca-
tion. The presence of clinical signs of a basal skull frac-
ture should increase the index of suspicion and help in
their identification. As a general guideline, fragments de-

238 / CHAPTER 12
pressed more than the thickness of the skull require ele-
vation. Open or compound skull fractures have a direct
communication between a scalp laceration and the cere-
bral surface because the dura is torn, and these fractures
require early surgical repair.
To quote Jennett and Teasdale, "To the lay mind, and
particularly to the legal mind, fracture of the skull is an
obvious mark of severity following a head injury. Thou-
sands of heads are x—rayed in emergency rooms, but in
only two or three cases in a hundred is there a fracture;
consequently, radiologists write papers on the misuse of
resources and demand that clinicians do better triage be-
fore x—rays are done. Neurosurgeons have long preached
that assessment of the conscious level is more important
than a skull x—ray, and this has been mistakenly taken to
imply that they regard the detection of a fracture as un-
important, especially after milder injuries. In fact, it is in
the patient whose consciousness is unimpaired and who
might otherwise be sent home as a trivial injury that
finding a fracture can be most significant, because it
alerts the clinician to the risk of complications such as
intracranial hematoma or infection" (16). The fre-
quency of skull fractures varies, with more fractures be-
ing found if the population studied has greater prepon-
derance of severe injuries. A linear vault fracture
increases the risk of intracranial hematoma by about 400
times in a conscious patient and by 20 times in a coma-
tose patient. For this reason, the detection of a skull frac-
ture warrants admission to hospital for observation, no
matter how well the patient seems.
Intracranial Lesions
These may be classified as focal or diffuse, although
these two forms of injury frequently coexist. Focal le-
sions include epidural hematomas, subdural hemato-
mas, and contusions (or intracerebral hematomas). Pa-
tients in the diffuse brain injury group, in general, have
normal CT scans but demonstrate an altered sensorium
or even deep coma. The cellular basis of diffuse brain
injury has become much clearer in recent years.
Focal Lesions
Epidural Hemotomos. These clots are located outside
the dura but within the skull. They are most often lo-
cated in the temporal or temporal—parietal region and are
often due to tearing of the middle meningeal vessels.
These clots are usually thought to be arterial in origin,
but they may be secondary to venous bleeding in at least
one—third of cases. Occasionally, an epidural hematoma
may result from torn venous sinuses, particularly in the
parietal—occipital region or posterior fossa. Although epi-
dural hematomas are relatively uncommon (0.5 percent
of all and 9 percent of comatose head—injured patients),
they should always be considered in the diagnostic pro-
cess and treated rapidly. If treated early, the prognosis is
usually excellent because the underlying brain injury is
usually limited. Outcome is directly related to the status
of the patient before surgery. The mortality from epidu-
ral hematoma approximates 0 percent for patients not in
coma, 9 percent for obtunded patients, and 20 percent
for patients in deep coma.
Subdurol Hemotomos. These are much more com-
mon than epidural hematomas, being found in approxi-
mately 30 percent of patients with severe head injuries.
They occur most frequently from a tearing of bridging
veins between the cerebral cortex and the draining si-
nuses. However, they can also be associated with lacera-
tions of the brain surface or substance. A skull fracture
may or may not be present. Furthermore, the brain dam-
age underlying acute subdural hematomas is usually
much more severe and the prognosis much worse than
for epidural hematomas. The mortality in a general se-
ries may be around 60 percent, but it may be lowered by
very rapid surgical intervention and aggressive medical
management (17).
Confusions and IntracerebralHematomas. Pure cere-
bral contusions are a fairly common occurrence. Their
frequency has become much more apparent as the qual-
ity and number of CT scanners have increased. Further-
more, contusions of the brain are almost always seen in
association with subdural hematomas. The vast majority
of contusions occur in the frontal and temporal lobes,
although they can occur at almost any site including the
cerebellum and brainstem. The distinction between con-
tusions and traumatic intracerebral hematomas remains
somewhat ill—defined. The classical "salt—and—pepper"
type of lesion is clearly a contusion, and a large hema-
toma is clearly not. However, there is a gray zone, and
contusions can evolve into intracerebral hematomas
over a period of hours or days.
Diﬁuse Injuries
Diffuse brain injuries form a continuum of progres-
sively severe brain damage that is caused by increasing
amounts of acceleration—deceleration injury to the brain.
In its pure form, diffuse brain injury is the most com-
mon type of head injury.
Mild Concussion. Mild concussion is that injury in
which consciousness is preserved but there is some de-
gree of noticeable temporary neurological dysfunction.
These injuries are exceedingly common and, because of
their mild degree, are often not brought to medical atten-
tion (18). The mildest form of concussion results in con-
fusion and disorientation without amnesia. This syn-
drome is usually completely reversible and is associated
with no major sequelae. Slightly more severe head injury
causes confusion with both retrograde and posttrau—
matic amnesia.

Classical Cerebral Concassions. Classical cerebral
concussion is the posttraumatic state that results in loss
of consciousness. This condition is always accompanied
by some degree of retrograde and posttraumatic amne-
sia, and the length of posttraumatic amnesia is a good
measure of the severity of the injury. The loss of con-
sciousness is transient and reversible. As a somewhat ar-
bitraiy definition, the patient has returned to full con-
sciousness by six hours, although it is usually much
sooner. The great majority of patients with classical cere-
bral concussion have no sequelae other than amnesia for
the events relating to the injury, but some patients may
have more long—lasting, although sometimes subtle, neu-
rological deﬁcits.
Diﬁ’useAx0nal Injury. Diffuse axonal injury (DAI) is
the term used to describe prolonged posttraumatic coma
that is not due to mass lesions orischemic insults. Loss of
consciousness from the time of injury continues beyond
six hours. This phenomenon may be further broken
down into mild, moderate, and severe categories. Mild
DAI is relatively uncommon and is defined as that group
in which coma lasts from 6 to 24 hours, with patients
starting to follow commands by 24 hours. Moderate DAI
is defined as coma lasting more than 24 hours without
prominent brainstem signs. This is the most common
form of DAI and comprises 45 percent of all patients
HEAD INJURY / 239
with DAI. Severe DAI usually occurs in vehicular acci-
dents and is the most devastating form. It Comprises
about 36 percent of all patients with DAI. These patients,
are rendered deeply comatose and remain so for pro-
longed periods of time. They often demonstrate evi-
dence of decortication or decerebration and often re-
main severely disabled, if they survive. These patients
often exhibit autonomic dysfunction such as hyperten-
sion, hyperhidrosis, and hyperpyrexia and were
previously designated as having primary brainstem in-
jury. It is now believed that diffuse axonal injury is the
much more common physiological basis for this clinical
picture (18).
MANAGEMENT OF HEAD INJURY
Mild Head Injury
The vast majority of patients presenting to the emer-
gency room with head injuries fall under this category
(Fig. 1). These patients are awake when seen by the phy-
sician but may be amnesic for events surrounding the
injury. There may be a history of a brieﬂess ofconscious—
ness, which is usually difficult to confirm. The issue
is often further confounded by alcohol or other intoxi-
Cants (19).
DEF|N|11ON: The patient is awake, and may be oriented.
MANAGEMENT:
1 . History: Type and time of accident, loss of consciousness,
amnesia, headache
Skull radiographs
. General examination to rule out systemic injuries
. Neurological examination
Cervical spine and other radiographs as indicated
Blood alcohol level and urine for toxic screen
. CT scan should ideally be obtained if first seven criteria for
admission noted below are present
CRITERIA FOR ADMISSION
. Deteriorating level of consciousness
. Moderate to severe headache
. Intoxication with aloohol or drugs
Skull fracture
. CSF leak - otorrhea or rhinorrhea
. Significant associated injuries
. No reliable companion at home
. Abnormal CTscan
8cooo\r_mo1-r>c.om_.
. Significant posttraumatic amnesia (over 1 hr)
. History of loss of consciousness (over 1 5 mins)
DISCHARGE FROM ER:
1 . If patient does not meet any of the
criteria for admission.
2. Discuss need to return if any problems
develop and issue a "warning sheet."
3. Schedule follow-up clinic visit
within1 week.
FIG. 1. Management of mild head injury.

240 / CHAPTER 12
Most patients with mild head injury go on to make
uneventful recoveries, albeit with subtle neurological se-
quelae (20). However, about 3 percent of patients unex-
pectedly deteriorate and can become neurologically de-
vastated if the decline in their mental status is not
noticed early (21). How far must a physician go to insure
against such an occurrence? The classical struggle be-
tween "cost—effectiveness" and the "best possible" ther-
apy is clearly evident in this instance. Although practice
in different centers varies (22), we believe the following
measures to be optimal for patients presenting with a
mild head injury.
Skull x—rays may be obtained looking for the following
features: linear or depressed skull fractures, position of
the pineal gland if calcined, air—ﬂuid levels in the sinuses,
pneumocephalus, facial fractures, and foreign bodies.
The routine ordering of skull x—rays in patients with
minor head injury has come under some criticism, and a
multicenter study sponsored by the FDA has recom-
mended guidelines for reducing the number of low—yield
studies (23). Based on an analysis of 7,035 head—injured
patients at 31 hospitals, the panel outlined a strategy
based on the level of risk:
1. For the low—risk group, with minimal initial signs and
symptoms such as headache, dizziness, or scalp lacera-
tions, discharge to a reliable environment for obser-
vation is recommended, with no need for skull radiog-
raphy.
2. For the moderate—risk group, with initial signs such as
vomiting, alcohol and drug intoxication, posttrauma—
tic amnesia, or signs of a basilar or depressed fracture,
the recommended procedure includes extended close
observation, consideration of CT or plain film radiog-
raphy, and a possible neurological consultation.
3. And for the high—risk group, with the most serious
initial symptoms such as depressed or decreasing level
of consciousness, focal neurological signs or penetrat-
ing injuries, a neurological consultation alone or
combined with an emergency CT scan is recom-
mended.
In this study, approximately 75 percent of the 7,035
patients would have been assigned to the low—risk group,
23 percent to the moderate—risk group, and 2 percent to
the high—risk group. Thus, using the panel's strategy,
about three—fourths of the patients with head injuries
would not have required skull x—rays. The panel stressed
that these guidelines were not meant to supplant a clini-
cian's judgment. Furthermore, the severity of injuries
commonly encountered will certainly vary from one hos-
pital to the next.
How often does one find a skull fracture? This figure
varies with the severity of injury from 3 percent of pa-
tients seen in the emergency room with a mild head in-
jury (those not admitted) to 65 percent among those with
severe head injuries (16). The vault is involved three
times as often as the base. It should be remembered,
however, that basal fractures are often not visualized on
initial skull films. Clinical signs of a fractured base—or—
bital hematoma, cerebrospinal ﬂuid (CSF) rhinorrhea or
otorrhea, hemotympanum, or Battle's sign—must be
taken as presumptive evidence of a basal fracture and
warrant admission for observation.
Ideally, a CT scan should be obtained in all patients,
although this is practically and financially impossible in
most institutions at the present time. If the patient is
fully awake and alert and can be kept under observation
for about 12 to 24 hours, this study may be deferred or
even cancelled. Our recommendations relating to the
timing of the CT scan in mild head injury patients re-
main tentative. Although unlikely, it is possible for pa-
tients with normal early scans to develop mass lesions a
few hours later. Close neurological observation by per-
sonnel sensitized to the possibility of deterioration is
without doubt the best safeguard against such "freak"
occurrences.
The cervical spine and other parts must be x—rayed
whenever there is any pain or tenderness. No drugs are
recommended except non—narcotic analgesics such as
Tylenol. Tetanus toxoid must be administered if there
are any associated open wounds. Routine blood tests are
usually not necessary if there are no systemic injuries. A
blood—alcohol level and urine toxic screen may be indi-
cated for m"dicolegal purposes.
Our practice with a mildly head—injured patient with a
normal CT scan is to discharge her or him to the care of a
reliable companion, who is instructed according to a
"warning sheet" (Fig. 2) to keep the patient under close
observation for at least 12 hours and to bring the patient
back if any adverse features develop. If no reliable com-
panion is available, the patient is kept in the emergency
room holding area for 12 hours with neurological checks
every half—hour and is then discharged if he or she ap-
pears stable.
If a lesion is noted on CT scan, the patient must be
admitted and managed according to his or her neurologi-
cal progress over the next few days. A follow—up CT scan
is usually obtained prior to discharge, or sooner in the
case of neurological deterioration. The management of
head injuries in athletes has been reviewed elsewhere
(24,25).
Moderate Head I11jury
Although these patients are still able to follow simple
commands, they can deteriorate rapidly (26). Therefore,
they should be treated in a manner akin to the severely
head—injured patient, although perhaps with a less acute
sense of urgency (Fig. 3). Several authors have detailed
their experience with this category of patients (27).
On admission to the emergency room, a brief history

HEAD INJURY / 241
FIG. 2. Warning sheet for patients with mild head injury who are to be sent home.
is obtained and cardiopulmonary stability ensured prior
to neurological assessment. Blood work may include a
CBC, SMA 20, coagulation profile, alcohol level, and a
sample for the blood bank. Cervical spine films are ob-
tained, and a CT scan is generally indicated. The pa-
tient is admitted for observation even if the CT scan is
normal.
Severe Head Injury
This group consists of patients who are unable to fol-
low simple commands even after cardiopulmonary sta-
bilization. Although this definition is inclusive of a fairly
wide spectrum of brain injury, it identifies a group of
patients who are at maximal risk of suffering signiﬁcant
FIG. 3. Management of moderate head injury.

242 CHAPTER 12
morbidity and mortality. We believe that in such pa-
tients a "wait and see" approach can be disastrous and
that prompt diagnosis and treatment is of the utmost
importance (17,28,29) (Fig. 4). The management of
these patients is described in five stages: (1) cardiopulmo-
nary stabilization, (2) general examination, (3) neurologi-
cal examination, (4) diagnostic procedures, and (5) indi-
cations for surgery.
Cardiopulmonary Stabilization
Brain injury is often adversely affected by secondary
insults. Miller and associates reported that, of 100 consec-
utive patients with severe brain injury evaluated on ar-
rival in the emergency room, 30 percent were hypoxemic
(P02 < 65 mm Hg), 13 percent were hypotensive (sys-
tolic BP < 95 mm Hg), and 12 percent were anemic
(hematocrit < 30%) (10). It has subsequently been dem-
onstrated that hypotension at admission (systolic BP <
FIG. 4. (A) Management of severe head
injury in the emergency room. FIG. 4.
continues on p. 243.
90 mm Hg) is one of the three factors in severely head
injured patients with a normal CT scan (the other two
being age > 40 years and motor posturing) that, when
noted at admission, is associated with subsequent intra-
cranial pressure (ICP) elevation. High ICPs are in turn
associated with poorer outcomes (30). It is imperative,
therefore, that cardiopulmonary stabilization be
achieved rapidly.
Airway
A frequent concomitant of concussion is transient re-
spiratory arrest. Prolonged apnea may often be the cause
of "immediate" death at the scene of an accident. Ifarti—
ﬁcial respiration can be immediately instituted, a good
outcome can result (31). Apnea, atelectasis, aspiration,
and acute respiratory distress syndrome (ARDS) are fre-
quently associated with severe head injury, and by far the
single most important aspect of the immediate manage-

HEAD INJURY / 243

244 / CHAPTER 12
ment of these patients is the establishment of a reliable
airway (32). All severely head—injured patients should be
intubated immediately. Care should be taken to ensure
proper endotracheal, rather than esophageal, placement
of the tube (Fig. 5). Infrequently, it is necessary to per-
form an emergency tracheostomy, especially in patients
with severe maxillofacial injuries in whom intubation
may be precluded because of severe soft tissue swelling
and distortion of the anatomy (33).
In the process of establishing an airway, the mouth
and nasal passages must be cleared of all foreign bodies,
secretions, blood, and vomitus. Once the endotracheal
tube is in place, the cuff should be blown up to prevent or
reduce aspiration, and a thorough suctioning of the tra-
cheal passages should be performed. One hundred per-
cent oxygen is then used for ventilation until blood gases
can be checked and appropriate adjustments of the F102
made. There is little danger of oxygen toxicity if 100
percent oxygen is used for less than 48 to 72 hours (34).
Blood Pressure
Hypotension and hypoxia are the principal enemies of
the head—injured patient. It has recently been shown that
the presence of hypotension (systolic BP < 90 mm Hg) in
severely head—injured patients increases the mortality
FIG. 5. Esophageal intubation. Lateral cen/ical film of an en-
dotracheal tube that was erroneously placed in the esopha-
gus. Note the tracheal air shadow anterior to the tube.
jte from 27 percent to 50 percent (35). Furthermore, it
waslbund that 35 percent of patients arriving at major
trauma centers are hypotensive. While the airway is be-
ing established, another group of ER personnel should
be checking the patient's pulse and blood pressure and
taking steps to obtain venous access. A minimum oftwo
intravenous lines (using 14- or 16—gauge Jelcos) should
be promptly placed. We generally use a percutaneous
infraclavicular subclavian or a jugular venous catheter
(36,37), although occasionally a saphenous or brachial
vein cutdown may be necessary to provide reliable ve-
nous access. At this point, blood may be drawn for a
CBC, SMA 20, coagulation screen, serum alcohol level,
sample to the blood bank, and arterial blood gases.
If the patient is hypotensive, it is of vital importance to
restore normal blood pressure as soon as possible. Hypo-
tension is usually not due to the brain injury per se, ex-
cept in the terminal stages when medullary failure super-
venes. Far more commonly, hypotension is a marker of
severe blood loss, which may be "overt," "occult," or
possibly both (Table 3).
In the hypotensive traumatized patient, one must con-
sider associated spinal cord injury (with quadriplegia or
paraplegia) as well as cardiac contusion or tamponade
and tension pneumothorax as possible causes. While ef-
forts are in progress to determine the cause of the hypo-
tension, volume replacement should be initiated using
normal saline and plasmanate. Blood transfusions must
be started as soon as possible when the blood pressure
does not respond promptly to ﬂuid replacement or when
the hemoglobin level is found to be less than 10.0 gm%
(HCT 30%). Group 0 Rh negative blood may be used
pending cross—matched blood availability. The impor-
tance of routine abdominal paracentesis in the hypoten-
sive comatose patient has been demonstrated (38).
It must be emphasized that a patient's neurological
examination is meaningless as long as he or she is hypo-
tensive. Time after time we have seen patients who are
unresponsive to any form of stimulation while hypoten-
sive revert to a near—normal neurological examination
fairly soon after normal blood pressure is restored.
TABLE 3. Common sites of blood loss in the
multiple trauma patient
Overt Occult
l. Scalp lacerations 1. lntraperitoneal or
2. Maxillofacial injuries retroperitoneal
3. Compound fractures Hemothorax
. Pelvic hematoma
Bleeding into extremities
at site of long—bone
fractures
5. Subgaleal or extradural
hematoma in an infant
6. Traumatic rupture of
the aorta
P0)!“
4. Other soft—tissue injuries

Catheters
A Foley catheter (16-18 French for average adults)
should be carefully inserted and urine sent for urinalysis
and toxic screen (when appropriate). Gross hematuria
suggests renal injury and is an indication for an emer-
gency IVP. Mild hematuria may be secondary to trau-
matic catheterization, to renal contusion, or, rarely, to a
dissecting aortic aneurysm. Despite, and perhaps be-
cause of, the general air of agitation associated with the
arrival of a trauma victim in the emergency room, spe-
cial attention must be paid to maintaining reasonably
accurate records of fluid intake and output, especially in
children and in the elderly. In addition to ensuring ﬂuid
balance, such records help assess blood loss and monitor
renal perfusion.
A nasogastric tube, preferably a Salem sump (double-
lumen plastic catheter), should be inserted and con-
nected to a wall suction. Potential complications of this
procedure, such as intracranial passage of the tube sec-
ondary to a basal skull fracture, must be kept in mind
(39,40). In patients with anterior basal skull fractures it is
probably wise to pass the tube under direct vision with a
laryngoscope or to pass it per orum.
Diagnostic X—Rays
As soon as the preliminary steps towards cardiopulmo-
nary stabilization have been taken, the following x—rays
should be obtained.
HEAD INJURY / 245
Cervical Spine (Cr0ss—Tal7le Lateral and Anter0p0ste—
rior). These are the first films to be taken in the severely
traumatized patient and must be read by a radiologist or
neurosurgeon before the patient's neck can be moved.
Features to look for in this study are ( 1 ) loss of alignment
of the vertebral bodies, (2) bony fractures or compres-
sion, (3) loss of alignment of the facet joints, and (4)
prevertebral soft—tissue swelling (more than 5 mm oppo-
site the C3 vertebral body is significant). Every effort
must be made to visualize the lower cer"vical levels (C6 to
C7, C7 to T1) because these are often obscured by the
shoulders, especially in heavy—set patients. Fracture sub-
luxations at these levels may be overlooked if the films
are not repeated with caudad traction on both arms and
greater x—ray penetration (Fig. 6). Ifthese maneuvers also
fail, a "swimmer's view" can be obtained. If these films
show any of the abnormalities in the preceding list, the
neck must remain immobilized in a hard collar (Philadel-
phia) pending further studies (high—resolution CT scan
or polytomogram).
Chest. This important film is useful in ruling out (1)
endotracheal tube malposition, (2) pneumothorax, (3)
hemothorax, (4) lung contusion, (5) hemopericardium,
(6) rib fractures. (7) thoracic spine fractures, and (8)
other thoracic pathology that may have a bearing on pa-
tientmanagement.
Skull (Anteroposterior and Lateral ). These are useful,
as discussed earlier, although their value has been some-
what overshadowed by CT scanning. They help in iden-
tifying maxillofacial injuries, depressed skull fractures.
FIG. 6. Missed C7 fracture—subluxation. The importance of pulling the shoulders down or obtaining a
swimmer's view is demonstrated in this example of an unstable cen/ical injury that would have been
ilssed (A) had a repeat film not been obtained (B).

246 / CHAPTER 12
and penetrating injuries. The presence ofintracranial air
(pneumocephalus) or of an air—ﬂuid level in one of the
sinuses can alert the clinician to a basal skull fracture
that might otherwise have gone undetected.
Abdominal. A single anteroposterior abdominal film
(KUB) is usually taken in trauma patients. This can help
rule out (in a gross way) large retroperitoneal hemato-
mas, lumbosacral spine fractures, distended viscera, and
possibly subdiaphragmatic air.
Pelvic. Anteroposterior and lateral pelvic films are
usually obtained, looking for pelvic injuries that may be
the site of significant blood loss.
Extremities. These may be studied whenever indi-
cated to rule out fractures or subluxations.
General Examination
During the process of cardiopulmonary stabilization,
the clinician conducts a rapid general examination look-
ing for other injuries. In one series of severely head—in-
jured patients, more than 50 percent had additional ma-
jor systemic injuries requiring care by other specialists
(10) (Table 4). Particular attention should be paid to
1. Head and neck injuries: lacerations, bleeding sites,
otorrhea, rhinorrhea, raccoon eyes (periorbital ecchy—
mosis), or Battle's sign (retroauricular eochymosis).
2. Thoracic injuries: rib fractures, pneumothorax or he-
mothorax, cardiac tamponade (with soft heart
sounds, jugular venous distension, and hypotension),
aspiration, or ARDS.
3. Abdominal injuries: especially liver, spleen, or kidney
lacerations. Hemorrhage usually results in abdominal
tenderness, guarding, or distension. However, these
signs may not manifest early and may be obscured in
the comatose patient. The presence of bowel sounds
is usually a reassuring sign.
4. Pelvic injuries: Injuries in noncomatose patients may
be ascertained clinically. Radiological confirmation
is usually necessary. Rectal examination may be use-
ful. Pelvic injuries are often associated with signiﬁ-
cant occult blood loss.
5. Spinal injuries: Head and spinal trauma may coexist,
and this combination must always be searched for
even though it is infrequent, occurring in 2 to 5 per-
cent of severely head—injured patients (41,42). In
TABLE 4. Systemic injuries in WO patients with
severe head injury3
Type of injury Incidence (°/o)
Long—bone or pelvic fracture 32
Maxillary or mandibular fracture 22
Major chest injury 23
Abdominal viscera injury 7
Spinal injury 2
3 Adapted from reference 10, with permission.
these patients, the cervical spine is most frequently
involved (43,44).
6. Injuries involving extremities: These may consist of
bony or soft—tissue (muscle, nerve, blood vessel) dam-
age. The agitated patient should have fractures
splinted promptly to prevent damage to contiguous
nerves and vessels. Deﬁnitive treatment of most inju-
ries involving the extremities can be postponed until
after treatment of more life—thre atening problems.
Neurological Examination
As soon as the patient's cardiopulmonary status has
been stabilized, a rapid and directed neurological exami-
nation is performed (Table 5). Although various factors
can prevent an accurate evaluation ofthe patient's neuro-
logical state at this point (e.g., hypotension, hypoxia, or
intoxication), valuable data can nevertheless be obtained
(45). Between the fully alert and the deeply comatose
patient lies a continuum of altered consciousness that is
difficult to quantify objectively. As noted earlier, the
Glasgow Coma Scale is widely used for this purpose.
If apatient demonstrates variable responses to stimula-
tion, or if the response on each side is different, the best
response appears to serve as a more accurate prognostic
indicator than does the worst response (Table 6). To fol-
low trends in an individual patient's progress, however,
it is better to report both the best and the worst re-
sponses. In other words, the right—sided and left—sided
motor responses should be recorded separately (46). As
the pain stimulus applied by different examiners is often
quite variable, deep nail—bed pressure should be used as
the standard stimulus.
The physician should not limit the examination to the
parameters of unconsciousness that are used in the GCS,
however, (i.e., eye opening, motor response, and verbal
response) (Table 7). Of equal importance in the initial
assessment of patients with impaired consciousness are
the patient's age, vital signs, pupillary response, and eye
movements (45). The GCS provides a simple grading of
the arousal and functional capacity of the cerebral cor-
tex, and the pupillary responses and eye movements
serve as measures of brainstem function. Advanced age,
hypotension, and hypoxia all adversely affect outcome
(30). Indeed, there is considerable interplay among all
these factors in determining the ultimate prognosis in
the severely head—injured patient.
TABLE 5. Initial neurological examination in head injury
1 . Glasgow Coma Scale
2. Pupillary response to light
3. Eye movements
a. Oculocephalic (dolls)
b. Oculovestibular (calories)
4. Motor power
5. Gross sensory examination

HEAD INJURY / 247
TABLE 6. Comparison of outcome with differentmotor responses3
Outcome (°/o)
Motor response # Cases G/MDC SD/VC Dead
Not posturing or flaccid 83 74 7 19
Uni— or bilaterally decorticate 20 60 5 35
Uni— or bilaterally decerebrate 19 21 16 63
Bilaterally flaccid 11 27 9 64
Total 133 60 8 32
a From reference 45, with permission.
b G = good outcome; MD = moderately disabled
0 3D = severely disabled; V = vegetative
Pupils
Careful notation of pupil size and response to light is
of utmost importance during the initial examination. A
well—known early sign of temporal lobe herniation is
mild dilation of the pupil and a sluggish pupillary light
response. Either compression or distortion of the oculo—
motor nerve during tentorial—uncal herniation impairs
the function of the parasympathetic axons that transmit
efferent signals for pupillary constriction (47), resulting
in mild pupillary dilation. However, bilateral miotic pu-
pils (1 to 3 mm) occur in the early stages of central ce-
phalic herniation (48). This is due to bilateral compro-
mise of the pupillomotor sympathetic pathways
originating in the hypothalamus, permitting a predomi-
nance of parasympathetic tone and pupillary constric-
tion. In either instance, continued herniation causes in-
creasing dilation of the pupil and paralysis of its light
response. With full rnydriasis (8 to 9 mm pupil), ptosis
and paresis of the medial rectus and other ocular muscles
innervated by the oculomotor nerve appear. A bright
light is always necessary to determine pupillary light re-
sponses. A magnifying lens such as the plus—20—diopter
lens on a standard ophthalmoscope is helpful in distin-
guishing between a weak pupillary light reaction and ab-
sence of a reaction, especially if the pupil is small.
TAB LE 7. Outcomes associated with different clinical features noted soon after admission in severe head in/'ury*
Outcome (°/o)
Clinical features # Cases G/MD" SD/VC Dead
1. Age"
0-20 46 72 11 17
21-40 50 66 6 28
41-60 28 43 11 46
61 + 9 22 O 78
2. GCS" admission score’
3-5 39 23 15 62
6-8 74 74 6 20
9-1 1 1 7 76 6 18
12-14 3 100 O O
3. Pupillary reaction’
Normal 87 76 8 16
Bilaterally impaired 46 30 9 61
4. Eye movements’
Normal 74 76 7 17
Unilaterally or bilaterally impaired 57 39 10 51
5. Surgical decompression’
None 74 76 7 17
Once 47 47 11 42
Two or three times 12 17 8 75
6. Motor posturing”
None (includes flaccidity) 94 68 7 25
Unilateral or bilateral 39 41 10 49
” From reference 45, with permission.
” G = good recovery; MD = moderately disabled
° SD = severely disabled; V = vegetative
"p<0.02
8 GCS = Glasgow Coma Scale
'p< 0.0002

CHAPTER 1!
Recognition of additional pupillary disorders that can
occur in an unconscious patient is useful in the examina-
tion of a patient with head trauma. Hippus is an unex-
plained phenomenon consisting of spontaneous dilation
and contraction of the pupil, and it is often observed in
patients with Cheyne—Stokes respirations. Rather than
indicating disordered function, however, it suggests
functional integrity of sympathetic—parasympathetic pu-
pillary pathways. Disruption of the afferent arc of the
pupillary light reﬂex within the optic nerve is detected by
employing the swingingﬂashlight test (49). As the flash-
light is swung from the normal to the injured eye, injury
to the optic nerve is indicated by a paradoxical response
of the pupil: dilation rather than constriction. Appar-
ently, light signals transmitted to the Edinger—Westphal
nucleus in the midbrain through the injured optic nerve
are insufficient to maintain the constriction brought
about by illumination of the normal eye. The paradoxi-
cal pupillary dilation observed as the light is moved from
the normal to the abnormal eye is termed an afferent
pupillary defect, or Marcus—Gunn pupil, and in the ab-
sence of opacification of the ocular media it is unequivo-
cal evidence of optic nerve injury.
Bilateral small pupils suggest that the patient has used
certain drugs, particularly opiates, or has one of several
metabolic encephalopathies or a destructive lesion of the
pons (50). In these conditions pupillary light responses
usually can be seen if examined with a magnifying lens.
The miosis that occurs with a pontine lesion apparently
results from structural or physiological inactivation of
sympathetic pathways descending from the hypothala-
mus through the reticular activating system to the spinal
cord. Unilateral Horner 's pupil is seen occasionally with
brainstem lesions, but in the trauma patient attention
should be given to the possibility of a disrupted efferent
sympathetic pathway at the apex of the lung, base of the
neck, or ipsilateral carotid sheath. Midposition pupils
with variable light responses are observed in all stages of
coma. Traumatic oculomotor nerve injury is the diagno-
sis in patients with a history of a dilated pupil from the
onset of injury, with an improving level of conscious-
ness, and with appropriate ocular muscle weakness (51).
A mydriatic pupil (6 mm or more) occurs occasionally
with direct trauma to the globe of the eye. This traumatic
mydriasis is usually unilateral and is not accompanied
by ocular muscle paresis. Rarely recognized is the corec—
topic pupil associated with midbrain disorders. In this
sign, the pupillary aperture appears to migrate within the
iris stroma as various sectors of the iris musculature con-
tract and relax asynchronously (52).
Finally, bilaterally dilated andﬁxed pupils in patients
with head injury may be the result of inadequate cerebral
vascular perfusion. This situation can be caused by hy-
potension secondary to blood loss or by elevation of in-
tracranial pressure to a degree that impairs cerebral
blood ﬂow. Return of the pupillary response may occur
promptly after the restoration ofblood ﬂow if the period
of inadequate perfusion has not been too long.
Eye Movements
Ocular movements are an important index of the
functional activity that is present within the brainstem
reticular formation. If the patient is sufficiently alert to
follow simple commands, a full range of eye movements
is easily obtained, and the integrity of the entire ocular
motor system within the brainstem can be affirmed. In
states of depressed consciousness, voluntary eye move-
ment is lost, and there may be dysfunction of the neural
structures activating eye movements. In these instances,
oculocephalic or oculovestibular responses are used to
determine the presence or absence of an eye—movement
disorder. To employ these tests, an understanding of the
anatomical connections involved in the normal response
is necessary.
Anatomy. Clinicians have long realized that a conju-
gate gaze center controlling ipsilateral horizontal fast eye
movements (saccades) and vestibular responses lies
within the lower paramedian pontine reticular formation
(53). This region includes a pulse generator for fast eye
movements and a neural integrator that determines the
ultimate resting position of the eye. Recent studies in
cats show that the caudal portion of the horizontal gaze
center extends into the nucleus prepositus hypoglossi in
the rostral medulla and that it significantly participates
in saccadic vestibular and voluntary slow eye move-
ments (54). Thus, clinical and animal investigations indi-
cate that the final common pathway for all ipsilateral
conjugate horizontal eye movements is located within
the tegmentum ofthe paramedian pontomedullaryjunc—
tion. From here, signals for horizontal eye movements
are transmitted to the nearby ipsilateral abducens nu-
cleus and cross the midline in the para—abducens region
to ascend in the contralateral medial longitudinalfascicu—
lus to the medial rectus neurons in the oculomotor nu-
cleus (55).
Oculoceplialic response. In an unconscious patient
with trauma to the head, loss of horizontal eye move-
ment indicates the need for urgent diagnostic study. If a
neck fracture has been excluded, function of the pontine
gaze center is quickly ascertained by the oculocephalic
maneuver. The head is raised 30 degrees from the supine
position and briskly rotated to and fro in the horizontal
plane. In the normal doll's—eyes response, both eyes tend
to maintain their position in space by moving opposite
to the rotation of the head and horizontally toward their
respective lateral and medial positions in the orbit. As
this maneuver is performed, the eyelids may be man-
ually retracted to better observe movements of the globe.
Afferent impulses from cervical nerve roots and the
semicircular canals contribute to the normal compensa-

tory reﬂexes that shift the eyes in the direction opposite
to rotation of the head. Impairment or absence of the
oculocephalic response may be due to malpositioning or
inadequate head rotation. Some patients whose oculoce-
phalic responses are impaired or absent will have normal
caloric responses. Therefore, all patients with impaired
oculocephalic responses, in addition to those in whom
neck fracture has not been ruled out and who therefore
cannot be tested for this response, should have caloric
stimulation ofoculovestibular pathways.
Oculovestibular response. This stimulation can be ac-
complished with ice water and only a small expenditure
of time. Obstructions within the external auditory canal
of blood or cerumen need to be removed. Limitation of
ocular muscle movement occurs in patients with orbital
edema. Intraorbital swelling is usually obvious to the ex-
aminer but should not discourage use of oculocephalic
or caloric testing. Much information can still be gained.
Movement of endolymph within the horizontal semicir-
cular canal acts primarily upon conjugate movement of
the medial and lateral rectus muscles (56). To produce
maximal shift of this ﬂuid during caloric stimulation, the
horizontal canal is positioned in the vertical plane by
lifting the patient's head 30 degrees from the supine posi-
tion. The temperature gradient between the irrigating
ﬂuid and the endolymph produces movement of the lat-
ter within the semicircular canal. Normally, this occurs
within 20 to 60 seconds and lasts several minutes. Warm
water irrigation of the external canal causes endolym-
phatic ﬂuid to rise, which causes contralateral tonic de-
viation of the eyes. Irrigation with cold water causes the
endolymph to fall, and this causes ipsilateral tonic gaze
deviation.
Although direct connections between vestibular and
ocular neurons are known, tonic eye deviation following
caloric stimulation is likely to be the result of complex
interactions within the eye—movement control systems
of the pontomedullary reticular system. In alert patients,
cold caloric stimulation causes fast—phase nystagmus in
the direction opposite the tonic eye deviation. The mne-
monic "cows"—cold opposite, warm same—refers to
this condition. However, in comatose patients, func-
tional suppression of the reticular activating system is
reﬂected by the absence of nystagmus in response to calo-
ric stimulation, so only the tonic eye deviation is seen
(cold same). Use of 20 ml of ice water suffices, but if no
response occurs within one minute, it is best to repeat the
test with a larger volume. Ifthe second irrigation does
not elicit eye movement, simultaneous oculocephalic
maneuvers can be used to enhance the stimulus. To elim-
inate semicircular canal or vestibular nerve injury as the
cause of absence of cold caloric responses, normal warm
water caloric responses of the opposite ear may be ob-
tained.
Full oculocephalic responses in the unconscious pa-
tient indicate that the process producing the coma spares
HEAD INJURY / 249
the paramedian pontine reticular formation, the medial
longitudinal fasciculus, and the oculomotor and abdu-
cens nuclei and their nerve roots. Moreover, the suppres-
sion of the reticular activating system responsible for the
loss of consciousness is assumed to be operant rostral to
these pontine and midbrain structures. An intermediate
response, i.e., absence of oculocephalic responses but in-
tact caloric responses, has been reported to occur with
supratentorial lesions (57). Absence of both oculocepha-
lic and caloric responses indicates a severe pathological
process extending to the lower pons.
While oculocephalic and caloric testing is being per-
formed, infranuclear, internuclear, and supranuclear oc-
ular motility disorders are recognizable. A destructive le-
sion ofeither a frontal or a pontine gaze center results in
tonic overaction ofthe opposite frontal—pontine axis for
horizontal eye movement. Tonic deviation of the eyes
occurs from the action of the spared frontal—pontine sys-
tem. This overaction results in ipsilateral deviation of
the eyes with frontal lobe lesions and contralateral gaze
deviation with pontine lesions. In deep coma, gaze de-
viation owing to the overbalance is not necessarily pres-
ent. To distinguish between a possible frontal or pontine
lesion in patients with or without gaze deviations, oculo-
cephalic and caloric testing is needed. In gaze deviations
caused by frontal lobe lesions, oculocephalic and caloric
reﬂexes remain intact because vestibular input into the
paramedian pontine reticular formation is preserved.
Pontine lesions interrupt oculocephalic and oculovesti—
bular—paramedian pontine reticular formation interac-
tion so that rotation of the head toward the deviated eye
or cold water irrigation of the ear contralateral to the
gaze deviation does not overcome the gaze deviation.
Incomplete or paretic conjugate horizontal gaze follow-
ing appropriate caloric stimulation suggests a partially
damaged pontine gaze center. Dysconjugate oculoce-
phalic and oculovestibular responses are due to either a
third or a sixth cranial nerve palsy or to internuclear
ophthalmoplegia if only one horizontal muscle is pare-
tic. If both horizontal muscles for conjugate gaze are par-
etic but one more than the other, a perverted form of a
pontine gaze palsy is present.
Skew deviation is divergence of the eyes in the vertical
plane and is a sign of a lesion within the brain stem. An
explanation for the tonic and vertical deviation of one or
both eyes is not known. In skew deviations, neuroana—
tornical localization within the brainstem is not ordi-
narily possible by notation either of the downward, or
hypometric, eye or of the upward, or hypermetric, eye.
Generally, third and sixth nerve palsies are not diffi-
cult to recognize in patients with head injury. Fourth
nerve palsies cannot ordinarily be identified in coma be-
cause of the select action of the superior oblique muscle.
In the alert and recovering patient, however, superior
oblique paresis causes troublesome double vision, espe-
cially with downward and inward gaze. Head tilt oppo-

250 / CHAPTER 12
site the side of the paretic muscle lessens the double vi-
sion, while ipsilateral tilt of the head increases diplopia.
Internuclear ophthalmoplegia is suggested by select ad-
duction paresis without additional involvement of the
pupil, lid, or vertical muscles innervated by the third
nerve. This ophthalmoplegia results from disruption of
the ipsilateral medial longitudinal fasciculus that con-
nects the oculomotor subnucleus for medial rectus neu-
rons to the contralateral horizontal gaze center. Either
bilateral or unilateral internuclear ophthalmoplegia may
be seen, depending upon the extent of the brainstem
trauma.
Little is known about the incidence of vertical gaze
palsies in coma states. Downward eye deviation is rare in
head injury but may be associated with posterior thala-
mic hemorrhage. Failure of upward gaze is, however,
occasionally seen in patients with bilateral subdural he-
matomas or hydrocephalus, and it is thought to repre-
sent compression of the tectal plate. With unilateral cold
caloric testing, downward deviation of the eyes has been
reported in coma caused by drug intoxication (57). Ver-
tical gaze is tested by manually rotating the head in the
vertical plane. This maneuver normally results in com-
pensatory up—and—down gaze. Simultaneous irrigation of
both ears activates the semicircular canals to cause verti-
cal response; bilateral cold water tests produce tonic up-
ward movement of the eyes, and bilateral warm water
tests produce tonic downward gaze.
Motor Function
The basic examination is completed by a gross test of
motor strength because severely head—injured patients
are not sufficiently responsive for such a determination
to be reliably made. Each extremity is examined and
graded on the internationally used scale as follows:
Normal power
Moderate weakness
Severe weakness (antigravity)
Severe weakness (not antigravity)
Trace movement
No movement
o»—l\)oa4>u1
Diagnostic Procedures
As soon as a patient's cardiorespiratory condition has
been stabilized and a preliminary neurological examina-
tion completed, it behooves the physician to rule out the
presence of an intracranial mass lesion. The patient is by
this time intubated and should be paralyzed with pan-
curonium (Pavulon) or a similar agent and put on me-
chanic al ventilation. This maneuver prevents the patient
from straining and moving around, thus avoiding intra-
cranial pressure surges and greatly enhancing the quality
of the diagnostic studies. Needless to say, CT scanning
has rendered all other diagnostic tests virtually obsolete.
However, other tests have to be used in certain instances
either to substitute for CT scanning or, as in the case of
angiography, to obtain certain supplemental data.
Ventriculography
Prior to the advent of CT scanning, air ventriculogra—
phy and angiography were the most important emer-
gency radiological tests for evaluating comatose head—in-
jured patients. The former was favored because of the
rapidity with which it could be obtained, even though
the latter could provide more information. Ventriculog—
raphy provides two crucial pieces of information: the
degree of supratentorial brain shift and the intracranial
pressure. If the procedure is performed in a methodical
and standardized fashion, the ventricle can almost al-
ways be cannulated to provide a satisfactory ICP mea-
surement and air study, even when the patient has a ma-
jor ventricular shift or slit—like ventricles secondary to
compression.
Technique. If there are no focal signs that favor a uni-
lateral mass lesion, the right side should be chosen. If,
however, there is reason to believe there is a mass on a
given side, the opposite side should be used because it is
easier to cannulate the less compressed ventricle. The
scalp is shaved widely in the region of the coronal suture.
After prepping the area with betadine solution and drap-
ing it with sterile towels, a lcm incision is made in the
scalp just anterior to the coronal suture in the midpupil—
lary line (Fig. 7). Using a 9/64 drill bit on a twist—drill set,
a small hole is made through the skull at this point. The
drill is directed towards the nasion, and in the sagittal
plane toward the opposite ear. The length of the drill bit
is adjusted to about 2 to 2.5 cm to avoid plunging into
brain material. As soon as the drill has penetrated the
skull a "give" is felt and the drill withdrawn. The dura is
best entered with a hand—held smaller drill bit using a
twisting motion. A manometer is ﬁlled with sterile saline
to a level of around 300 mm of water and connected to a
ﬂexible tube with a stopcock. A No. 16 brain cannula or
a ventriculostomy tube is then passed through the hole
directed towards the lateral ventricle. The axes used are
as stated—toward the nasion and the opposite ear. Ifthe
ventricle is not entered with this pass, the axis is biased
toward the ipsilateral pupil and then toward the contra-
lateral pupil in the next two passes. The ventricle should
be entered around 7 to 8 cm; deeper passes are inadvis-
able. Once the cannula has been passed, the stylet is par-
tially withdrawn to confirm entry into the ventricle. If
the cannula is in the ventricle, cerebrospinal ﬂuid will be
seen ﬂowing out as the stylet is withdrawn. Care should
be taken to avoid losing more than a drop or two of CSF
while withdrawing the stylet and connecting on the ma-
nometer tube, so as to obtain the most accurate ICP

A. Entry Site
C. Ventriculostomy
Tunnel under scalp
Foramen of Monro
Pressure transducer
College 01 Medicine 1990
readings. If all three passes on one side fail to enter the
ventricle, the procedure is repeated on the other side. If
three passes on the other side also fail, the procedure is
abandoned.
Once the manometer is connected onto the cannula,
the stopcock is opened and the ICP is measured with the
patient lying ﬂat on his or her back. The foramen of
Monro is used as the point of reference. It should be
remembered that arterial hypotension may be reﬂected
in low ICP readings and that hypercarbia and hypoxia
tend to raise ICP. After measuring the pressure, approxi-
mately 7 cc of air is carefully exchanged for CSF, the
head is tilted from side to side, and a brow—up anteropos—
terior Townes projection skull x—ray is obtained after re-
moving the cannula and closing the scalp incision with a
single suture.
Normal ICP in a relaxed or paralyzed patient who is
neither hypotensive nor hypercarbic/hypoxic is 10 mm
Hg (136 mm H20) or less. Although pressures in the
range of 10 to 20 mm Hg (136 to 272 mm H20) may
occur with moderate disturbances of intracranial vol-
umes, pressures greater than these warn of a major intra-
cranial hematoma, serious diffuse brain injury, or both
(46). A major change in intracranial pressure—volume dy-
namics is required to raise intracranial pressures to these
levels.
B. APView
HEAD INJURY
FIG. 7. Anatomical landmarks for a ventriculo-
gram. For the preferred frontal approach, a twist-
drill hole is made in the midpupillary linejust ante-
rior to the coronal suture (A). The drill is directed
towards the nasion (B) and, in the sagittal plane,
toward the opposite ear. In effect, this puts the drill
virtually perpendicular to the skull. The ventricle is
entered with a cannula or ventriculostomy tube at
a depth of 7 to 8 cm (C). If the ventricle is not
entered in the first pass, two more passes can be
made, directed towards the ipsilateral and contra-
lateral pupil, respectively, instead of the nasion. If
three passes on each side do not result in success-
ful cannulation, the procedure should be aban-
doned.
Most dangerous traumatic unilateral intracranial
mass lesions will shift the midline 5 mm or more. This
will invariably be associated with an elevated ICP unless
a CSF leak is present. Significant temporal lobe lesions
may cause only a minimal shift of the midline, but the
ICP will usually be elevated and the third ventricle, if
seen, will often be shifted more than the lateral ventri-
cles. If there is little or no midline shift, the ICP is ele-
vated, and the patient is not hypercarbic, then there are
either bilateral mass lesions or serious diffuse brain in-
jury. A CT scan would resolve the issue, but when this is
not available the patient may have an angiogram per-
formed promptly to rule out bilateral "balancing" hema-
tomas or contusions that might require operative inter-
vention.
Twist—Drill Trep/rrination
Mahoney and associates have reported their experi-
ence with emergency twist—drill trephination in the ER
in patients with a rapidly progressing uncal herniation
syndrome despite maximal medical therapy (58). This
can be used when there is any delay in obtaining a CT
scan, although we prefer to use an air ventriculogram. In
this study, 51 trephinations were performed in 41 pa-

252 / CHAPTER 12
tients with an 81 percent accuracy rate for the presence
or absence of a hematoma. The trephination was per-
formed on the side of the dilating pupil, two finger-
breadths above the zygomatic arch and two finger-
breadths anterior to the ear, using a "f—inch diameter
hand drill. The dura was opened, and partial evacuation
of the hematoma was attempted by gentle suction. An-
drews and colleagues also made a case for exploratory
burr holes in patients with clinical signs of tentorial her-
niation or upper brainstem dysfunction on admission to
the emergency room (59). A hundred such patients were
taken directly to the operating room after intubation and
resuscitation, and sequential burr holes were made. A
complete exploration consisted of temporal, frontal, and
parietal holes. An extracerebral mass was found in 56 of
100 patients. In 38 patients, the exploration was negative
and the postoperative CT showed no significant hema-
toma. In six patients, an extra—axial hematoma that re-
quired surgery was missed. This option can be consid-
ered when a CT scan is not immediately available or
when the patient is clearly herniating.
Angiography
Indications. Angiography is undertaken in the
acutely head—injured patient when CT scanning is not
available. When CT scanning is available, angiography is
occasionally indicated as, for example, when a mass ef-
fect is seen on CT scan but no hematomas can be visual-
ized (the differential diagnosis includes an isodense he-
matoma and acute parenchymal swelling), when
vascular injury is suspected, or when the findings on CT
are not consistent with the patient's neurological status.
In a recent report of 24 patients with traumatic carotid
artery dissection, the presenting signs included Horner's
syndrome, dysphasia, hemiparesis, obtundation, and
monoparesis (60). When an isodense subdural hema-
toma is suspected, its presence can be confirmed by al-
tering the CT window setting or by using a contrast—en—
hanced study, prior to resorting to angiography.
Technique. Apart from the time involved in setting
up for angiography, this investigation requires a certain
degree of expertise in order to be performed safely and
effectively. When performed by experts, transfemoral
catheterization is the procedure of choice. It provides the
most information, but because it takes longer to set up
and is technically more difficult, it is not widely used for
head—injured patients. Angiograms are obtained in most
emergency rooms by direct injections into the common
carotid artery or internal carotid artery. In either case,
care must be taken to avoid entering the region of the
bifurcation, thus avoiding the carotid sinus and any ath-
eromatous plaques. An l8—gauge needle is used for this
procedure. The left hand anchors the carotid artery in
place against the vertebral bodies using the index and
middle fingers. The angiography needle is then inserted
between the two anchoring fingers and brought to lie
against the vessel wall. The wall of the vessel may also be
penetrated at right angles to minimize slippage and then
the needle brought into a plane parallel to the vessel into
which it is threaded. A 20—ml syringe with a stopcock and
connector tube is filled with saline and kept ready. A
nonionic water—soluble iodinated contract medium (e.g.,
Omnipaque 300) is drawn up in a l0—ml syringe and also
connected to the stopcock. Once the connector tubing is
connected to the needle, good blood ﬂow is confirmed
with the saline syringe. The stopcock is then turned and
the contrast medium injected rapidly. Just before the
syringe is emptied, the technician begins shooting the
films. Biplane angiography with an automatic changer is
the ideal. However, when these are not available three
AP and three lateral films usually provide almost as
much data. Cross—fi]]ing ofthe opposite side may be facil-
itated by compression of the contralateral common ca-
rotid artery during injection of the contrast material.
The Seldinger technique may also be used for carotid
catheterizations. This involves penetrating the common
carotid artery low in the neck with an l8—gauge needle
and introducing a 50—cm long Seldinger guide through
the needle. The needle is then withdrawn when the guide
is 3 cm beyond its tip. A 30—cm catheter (PE 160) is then
introduced over the guide and, with a twisting motion, is
pushed into the vessel. The guide is then withdrawn.
Good blood ﬂow should be obtained before contrast is
injected. If carotid dissection is suspected, a transfemoral
study should be obtained, because a direct carotid injec-
tion runs the risk of propagating the false lumen.
Interpretation. Supratentorial mass lesions usually
cause a contralateral shift of the anterior cerebral artery
and the internal cerebral vein [Fig. 8 (A) and (B)]. The
latter, being closer to the midpoint ofthe cranium, is less
affected by rotation of the film—a common problem
owing to rotation of the head to either side (61). Al-
though displacement of the vessels does not provide any
differentiating features between parenchymal swelling
and hematomas, a study of the pattern can help localize
the lesion. Frontal lesions cause a bowing of the anterior
cerebral artery, the so—called "rounded shift," with lim-
ited displacement, if any, of the internal cerebral vein.
Parietal lesions tend to cause a "square shift" ofthe ante-
rior cerebral artery primarily because of widening of the
unyielding falx cerebri posteriorly, and the internal cere-
bral vein is more markedly displaced. Temporal lobe le-
sions result in medial displacement of the internal ca-
rotid artery bifurcation and a characteristic upward
displacement of the middle cerebral artery group. This
may also be seen on the lateral views, but this is less
reliable because even mild rotation of the head can pro-
ject as an apparent upward bowing. It should be remem-
bered that parietooccipital lesions may not cause any
apparent shift of the midline as bilateral mass lesions
may balance each other [Fig. 8 (C)].
Infratentorial mass lesions are difficult to detect angio-

HEAD INJURY / 253
FIG. 8. Angiographic findings in head injury: (A) Acute right subdural hematoma, arterial phase. Note
thatthe midline cerebral artery branches are displaced away from he ,nnertable ofthe skull andthat UK;
sylvian point(s) is displaced toward the midline. The pericallosal artery (P) is markedly shifted across the
midline due to subfalcine herniation of the cingulate gyrus. (B) The venous phase of the same study
demonstrates a 2—cm right—to—left shift of the internal cerebral vein (arrow). Because this structure is
close to the center of the skull, rotation of the skull affects the pericallosal artery more than it affects this
structure. The internal cerebral vein is a paired midline structure, so the medial side of the vein represents
the midline. (C) Balancing bilateral hematomas. In the absence of midline shift on the angiogram as well
as on CT scan, bilateral hematomas should be suspected. Features suggestive of this diagnosis include
(1 ) inexplicably poor neurological state; (2) high ICP without obvious cause; and (3) subdural avascular
mantles. In this patient with bilateral subdural hematomas, note the crescentic avascular mantles—15
mm on the right and 10 mm on the |eft—with midline anterior cerebral arteries. (D) The shape of the
radiolucent mantle and other angiographic features are often not very helpful in distinguishing between
subdural and epidural hematomas. This patient was found to have both on the right side. Again, note the
dramatic shift of the internal cerebral vein to the left.
graphically, and Vertebral injections are rarely under-
taken for this purpose. A posterior fossa mass may be
suspected if there is evidence of hydrocephalus on the
carotid films (i.e., upward sweep of the pericallosal artery
on the lateral film and a lateral bowing of the thalamo—
striate vessels on the anteroposterior ﬁlms).
Transtentorial herniation is seen on anteroposterior
and lateral carotid angiograms as marked stretching of
the anterior choroidal artery as a result of medial uncal
displacement. If the posterior communicating arteries
are Visualized, these will also be seen to be stretched and
sometimes compressed against the posterior clinoid pro-

254 CHAPTER 12
cesses. The posterior cerebral arteries are inferiorly dis-
placed on lateral view and are seen to be medially dis-
placed along with both superior cerebellar arteries on
anteroposterior view because of hippocampal gyrus her-
niation.
Mass lesions themselves usually present as avascular
areas on angiography. The classical appearance of an ex-
tra-axial hcmatoma on the AP view consists of a clear
gap between the inner table of the skull and the small
vessels on the surface of the brain as seen in the venous
phase [Fig. 8 (D)]. When the clot is located closer to the
vertex, oblique views may be needed to demonstrate its
presence, although displacement of a venous sinus away
from the bone may be seen on lateral views in certain
cases when the clot reaches the vertex. Subfrontal clots
may be suspected when the proximal anterior cerebral
artery is displaced upward and backward. Distinguishing
between extradural and subdural hematomas on an an-
giogram is an unreliable and somewhat academic exer-
cise [Fig 8 (D)]. Abnormalities in transit time, spasm of
the intracranial vessels, and other forms of vascular in-
jury may also be seen in patients with head injury.
Computed Tomography
Indications. CT scanning is clearly the procedure of
choice in the evaluation of the head—injured patient and
has probably significantly improved outcome from head
injury (62). With every new generation of scanners, the
quality of information obtained is further enhanced.
However, most important decisions relating to patient
management are based on certain basic findings. It is
strongly recommended that an emergency CT scan be
obtained as soon as possible (preferably within half an
hour) after admission of a patient with a severe head
injury. Centers dealing with such patients must make
arrangements to have CT technicians in the hospital on a
24-hour basis or within easy accessibility in an emer-
gency. We also recommend repeat CT scans whenever
there is a change in the patient's clinical status or an
unexplained rise in intracranial pressure. Furthermore,
CT scan findings can be valuable in selecting patients for
ICP monitoring (30).
Technique. As soon as the patient's pulmonary status
is stabilized, the patient is rushed to the CT suite. At this
time, the operating room is warned of the possibility of a
craniotomy, and other steps are taken to ensure the pa
tient's readiness for surgery, should it be necessary.
These include typing and cross—matching blood and con-
tacting relatives in order to obtain the necessary consent
for surgery. The patient is accompanied to the CT suite
by a physician because these patients are acutely ill and
often deteriorate suddenly. They are usually already in-
tubated. paralyzed, and on mechanical ventilation when
they reach the CT suite. It is unwise to become compla-
cent at this time, and frequent monitoring of vital signs
and pupillary reactions is strongly recommended.
If the scans reveal the presence of an operable mass
lesion, the patient is rushed to the operating room. Ma-
nipulating the scanner "window" during scanning is
sometimes useful in visualizing relatively isodense he-
matomas.
Interpretation. In a prospective study of CT scan ab-
normalities in 207 severely head—injured patients, we
found the initial CT scan to be normal in 30 percent of
cases. The remaining 70 percent ofpatients had CT scan
abnormalities: low—density lesions in 10 percent, high-
density nonsurgical lesions in 19 percent, and high—den-
sity lesions requiring surgery in 41 percent (30). Low-
density lesions, when seen in the absence ofhigh—density
lesions, were interpreted as representing edema or in-
farction. Nonsurgical high—density lesions were contu-
sions or hematomas causing less than 5 mm of actual
midline shift. High—density lesions (epidural, subdural,
or intracerebral hematomas) were deemed to require
surgical decompression if they caused a midline shift
greater than 5 mm. In other words, considerable empha-
sis is placed on the degree of midline shift in deciding
which patients need surgical decompression. The signifi-
cance of midline shift in head—injury patients has been
examined by other authors, and some interesting cor-
relations with the level of consciousness have been
noted (63).
CT densities are measured by a scale first introduced
by Hounsfield (64) and subsequently modified by a fac-
tor of two. In this scale, water's absorption coefficient
(Hounsfield, or H, number) is 0, air's is -1000, and
bone's is +1000. The H numbers for intracranial struc-
tures are approximately as follows:
Air -1000
Fat -100
Water 0
CSF 4-10
White matter 22-36
Gray matter 32-46
Extravasated blood 50-90
Bone or calciﬁcation 800-1000
On CT, edema is seen as a zone of low density with
attenuation values ranging between 16 and 24 H, as
compared to white-matter values of 22 to 36 H. Asso-
ciated with this low density, a mass effect on the adjacent
ventricles may be seen, reﬂected as compression, distor-
tion, and displacement of the ventricular system. The
edema may be focal, multifocal, or diffuse. With diffuse
cerebral edema, it may be hard to appreciate the lower
density because no area of normal brain density is avail-
able for comparison [F1g. 9 (A)]. In such cases there is
usually bilateral ventricular compression, which may be
so gross as to result in nonvisualization of the ventricular
system, especially in children. It is debated as to whether

FIG. 9. CT findings in head injury: (A) Low—den—
sity lesions. These may be focal or, as in this ex-
ample, generalized. Note the almost complete
disappearance of the ventricles. (B) Contusions.
These are characterized by multiple small areas
of hemorrhage within the brain parenchyma, as-
sociated with surrounding areas of edema, and
result in the typical "salt—and—pepper" appear-
ance. (C) Subdural hematoma. Note that the hy-
perdense collection covers almost the entire sur-
face of the hemisphere and has a concave inner
margin. There is a 1—cm left—to—right shift of the
midline. (D) Epidural hematoma. This biconvex or
lenticular shape typifies an epidural hematoma.
Note the massive shift ofthe midline. (E) Gunshot
wound.

256 / CHAPTER 12
the picture of diffuse brain swelling is secondary to
edema or vascular engorgement. Although the attenua-
tion numbers could be expected to differentiate between
the two states, the issue is complicated by changes in
brain lipids after trauma (65). Miller and Corales con-
cluded that the concept of posttraumatic brain edema
has been overemphasized, and they emphasize the role
of vascular changes in the genesis of this morphological
picture (66).
Cerebral confusions are seen as nonhomogenous areas
of high density often interspersed with areas of low den-
sity, with attenuation values in the range of 50 to 60 H.
The CT appearance results from multiple small areas of
hemorrhage within the brain substance, associated with
areas of edema [Fig. 9 (B)]. The margin is usually poorly
denned. A mass effect is often seen, although this may be
minimal. Depending on the extent of hemorrhage, the
degree of edema, and the time course, a contusion may
appear predominantly dense or lucent. The outcomes
for patients demonstrating either low—density lesions or
nonsurgical high—density lesions (contusions) are very
similar, further suggesting that these morphological enti-
ties are closely related (Table 8).
Although it is not always possible to differentiate be-
tween subdural and epidural hematomas on CT, the lat-
ter are typically biconvex or lenticular in shape, because
the close attachment of the dura to the inner table of the
skull prevents the hematoma from spreading [Fig. 9 (C)].
Approximately 20 percent of patients with an extracere—
bral hematoma have blood in both the epidural and sub-
dural spaces at operation or autopsy (67). There is little
chance of epidural blood mixing with CSF, so these le-
sions appear as uniformly dense collections and are
rarely isodense. However, they may develop in a delayed
fashion, especially after evacuation of a contralateral
"balancing" lesion.
The typical subdural hematoma tends to be more dif-
fuse than an epidural hematoma and has a concave inner
margin that follows the surface of the brain [Fig. 9 (D)].
The distinction between acute, subacute, and chronic
lesions is somewhat arbitrary. However, in a study of 42
patients who were classified as acute if symptomatic for 0
to 7 days, subacute if symptomatic for 7 to 22 days, and
chronic if symptomatic for over 20 days, 100 percent of
the acute group had hyperdense lesions, 70 percent ofthe
subacute group had isodense lesions, and 76 percent of
the chronic group had hypodense lesions (68). Efface—
ment of the cerebral sulci over the convexity and distor-
tion of the ipsilateral lateral ventricle may serve as clues
that suggest the presence of an isodense hematoma. As
always, the degree of midline shift serves as the primary
criterion upon which decisions relating to surgical evacu-
ation of the hematoma are based.
Traumatic intracerebral hematomas are usually lo-
cated in the frontal and anterior temporal lobes, al-
though they may occur in virtually any area. The major-
ity of hematomas develop immediately after the injury,
but delayed lesions are not uncommon, usually develop-
ing within ihe first week. They are high—density lesions
with attenuation values of 70 to 90 H and are usually
surrounded by zones of low density caused by edema.
Traumatic hematomas are more often multiple than he-
matomas from other causes.
Iritraveritricular hemorrhage was previously believed
to have uniformly poor prognostic implications. This is
no longer considered true after the advent of CT scan-
ning (69). It is frequently associated with parenchymal
hemorrhage. The blood becomes isodense relatively rap-
idly and often disappears completely within a week. A
ventriculostomy is placed in the less bloody ventricle,
and a larger tube (No. 8 French) is used when intraven-
tricular blood is noted on CT.
Acute obstructive hydrocephalus may develop second-
ary to a posterior fossa hematoma that obstructs the ven-
tricular pathways. However, delayed hydrocephalus is
far more common, occurring in one study in 3 out of 48
patients with severe head injury who were followed with
serial CT scans (70). This communicating hydrocepha-
TABLE 8. Admission CTfindings and outcome"
Outcome (°/o)"
CTgroup" # Cases °/o G° MD“ SD/V9 Dead
Normal 61 30 62 18 2 18
Low—density lesions only 20 10 50 10 15 25
High-density nonsurgical lesions 40 19 40 20 17 23
High-density surgical lesions 86 41 26 - 13 e, 9 52
Total 207 1 00 42 1 5 9 34
" From reference 30, with permission.
b The correlation between CT (computed tomography) findings and outcome is significant (p < 0.0001). The difference in
outcome between normal and abnormal (low— or high—density lesions) CT scans is also significant (p < 0.0001).
° G = good recovery
"MD — moderately disabled
8 SD = severely disabled; V = vegetative

lus results from blood in the subaraclmoid space and is
usually evident by the 14th day post—injury. This entity is
discussed in greater detail later in this chapter.
Acute ischemic infarction appears as a low—density
area compared with the adjacent brain. The infarction
may be detectable on CT scan within 24 hours of onset,
and over 60 percent are clearly seen by seven days (71).
Contrast enhancement improves the diagnostic yield by
nearly 15 percent (72), and magnetic resonance imaging
(MRI) may be even more sensitive.
Indications for S nrgery
It is difficult to lay down hard and fast rules regarding
the management of a disease as diverse as head injury.
However, we have arrived at certain guidelines that have
proven to be useful "in the trenches." Some of these
practices are based on hard data, some on clinical preju-
dice, and some on an irresistible desire to simplify a hope-
lessly complicated problem.
In its simplest form, our criterion for considering a
mass lesion operable is a midline shift of 5 mm or more.
Such a shift may be demonstrated by CT scan, angiogra—
phy, or ventriculography. Virtually all epidural, sub-
dural, or intracerebral hematomas associated with a
midline shift of 5 mm or more are surgically evacuated.
Occasionally one encounters a patient with a small he-
matoma with minimal shift who is alert and neurologi-
cally intact. A conservative approach is justified in such
cases, but the patient may deteriorate, ,and very close
observation is critical. Should there be any change in
mental status, a repeat CT scan should be obtained im-
mediately.
It is our policy to operate on all patients with an intra—
cranial mass lesion and 5—mm or more midline shift un-
less they are brain—dead. This policy is based on evidence
that some patients with bilaterally nonreactive pupils,
impaired oculocephalic responses, and decerebrate pos-
turing can nevertheless make a good recovery. In one
series, 3 of 19 such patients who were treated maximally
ended up in the "good" or "moderately disabled" cate-
gory, despite their foreboding constellation of signs (73).
The management ofbrain contusions is somewhat less
clear—cut. The only study that provided some guidance
in this area previously was that by Galbraith and Teas-
dale (74). In their series of 26 patients with acute trau-
matic intracranial hematomas who were managed with-
out surgery, they found that all patients with an ICP
greater than 30 mm Hg eventually deteriorated and re-
quired surgery. In contrast, only one patient with ICP
levels of less than 20 mm Hg deteriorated. Patients in the
20- to 30—mm Hg range were about evenly divided be-
tween the surgical and nonsurgical groups.
We have recently analyzed our experience with 130
head—injured patients with pure contusions who were
HEAD INJURY / 257
managed with CT scanning and, as needed, ICP moni-
toring in a neurosurgical intensive care unit (NICU) set-
ting (75). This study showed that patients with brain
contusions who could follow commands at admission
did not require ICP monitoring and as a rule did well
with simple observation. However, those who could not
follow commands (in the absence of a focal lesion in the
speech area) often had intracranial hypertension and de-
served to have their ICP monitored. The majority of
these patients who had compressed basal cisterns re-
quired surgery. We have found this algorithm to be very
useful in managing these patients.
It has been conclusively demonstrated that patients
with a large (over 30 cc) temporal lobe hematoma have a
much greater risk of developing tentorial herniation
than those with a frontal or parietooccipital lesion (76).
The bias should therefore tilt toward early surgery in
such cases.
When CT scanning is not immediately available, deci-
sions regarding surgery must be based on air ventricu-
lography and ICP measurements. Here again, a midline
shift of 5 mm or more indicates a need for immediate
surgical decompression. If there is no midline shift but
the ICP is elevated above 20 mm Hg, angiography
should be performed promptly to rule out bilateral bal-
ancing lesions.
When angiography is undertaken in patients with se-
vere head injury, the following findings should be consid-
ered as indications for an operation:
1. An intra— or extra—axial mass lesion causing a shift of
the anterior cerebral vessels across the midline to an
extent of 5 mm or more.
2. An extra—axial mass lesion more than 5 mm from the
inner table, if it is associated with any degree of ante-
rior or middle cerebral artery displacement.
3. Bilateral extra—axial mass lesions more than 5 mm
from the inner table. Except for patients who have
marked brain atrophy, such intracranial masses will
usually cause major elevations of ICP.
4. A temporal lobe intra—axial mass lesion causing a ma-
jor elevation of the middle cerebral artery or any de-
gree of midline shift. These patients are in a most
precarious position, because only slight swelling can
cause a tentorial herniation syndrome that progresses
very rapidly.
If the patient is considered a surgical candidate, he or
she is promptly moved to the operating room; if not, the
patient is moved to the NICU. If the patient is harboring
a mass lesion, mannitol (1 to 2 g/kg) should be adminis-
tered en route to the operating room. In addition, the
patient should be hyperventilated to achieve an arterial
Pcoz of25 to 30 mm Hg. As in all the maneuvers under-
taken thus far, time is of the essence. The sooner the
mass lesion is evacuated, the better the possibility of a
good recovery (17). If, on the other hand, no surgical

258 / CHAPTER 12
lesion is found, the patient is carefully monitored in the
NICU, both clinically and with various physiological pa-
rameters, notably ICP recordings and serial CT scans.
Any rise in ICP above 20 mm Hg that cannot be readily
explained and reversed and any deterioration in neuro-
logical status warrant prompt repetition of the CT scan
followed by the appropriate corrective measures.
SURGICAL CONSIDERATIONS
Anesthesia
The principal consideration in the selection of an anes-
thetic agent, or combination of agents, is the effect on
intracranial pressure. Because any agent that causes cere-
bral vasodilatation is likely to cause an increase in intra-
cranial pressure, such agents are to be avoided whenever
possible. One of the worst offenders in this regard is keta—
mine, which is a powerful cerebral vasodilator and is,
therefore, generally avoided in the head—injured patient.
All inhalation anesthetic agents can increase cerebral
blood ﬂow to a lesser or greater extent. Volatile inhala-
tion agents, such as halothane, enﬂurane, and isoﬂurane,
can all increase cerebral blood ﬂow, but they are proba-
bly safe in low concentrations. Isoﬂurane is the least
likely of these to cause cerebral vasodilatation. Nitrous
oxide has a slight vasodilatory effect that is probably
clinically insignificant, and it is therefore considered a
good agent for use in the head—injured patient. A com-
monly used combination is nitrous oxide (50 to 70 per-
cent with oxygen), an intravenous muscle relaxant, and
thiopental. The use of hyperventilation and mannitol
prior to and during induction can blunt the vasodilatory
effect and limit intracranial hypertension to some degree
while the cranium is being opened. If, during surgery,
malignant brain swelling occurs that is refractory to hy-
perventilation and mannitol, thiopental (Pentothal®) in
large doses (5 to 10 mg/kg) should be used. This agent
can cause hypotension, especially in a hypovolemic pa-
tient, and should therefore be used cautiously. As a last
resort, the use ofjudicious hypotension, with trimetha—
phan (Arfonad®) or nitroprusside (Nipride®) could be
considered. In such situations, it is important to rule out
other causes ofbrain swelling, such as venous congestion
from neck compression and the presence of an occult
hematoma either on the ipsilateral or the contralateral
side of the craniotomy.
Subdural Hematomas
Acute subdural hematomas may result from bleeding
from lacerated brain, bone cortical vessels, or an avulsed
bridging vein. Most of the obvious brain injury is seen in
the inferior frontal lobes and in the temporal lobes. In
order to be able to reach the nridline, as well as the fron-
tal, temporal, and parietal regions, we advocate a large
ﬂap for the treatment of acute subdural hematomas. The
scalp incision is a standard question mark beginning just
anterior to the tragus at the zygomatic arch, curving pos-
teriorly over the ear to the midline and then coming
down on the midline to a centimeter or so below the
hairline (Fig. 10). Ifthe patient has been deteriorating
rapidly, a quick temporal decompression can be per-
formed via a small craniectomy, as shown in the figures.
This will reduce the pressure on the brainstem and could
possibly prevent or reverse tentorial herniation from oc-
curring. Once this has been achieved, the rest of the ﬂap
can be completed. The medial extent of the craniotomy
should be approximately 1.5 cm off the midline in order
to avoid injury to the superior sagittal sinus or to one of
the venous lacunae or a draining vein. At the same time,
this ﬂap opening permits the surgeon to visualize the
major draining veins easily and to be able to reach an
avulsed vein near the midline. The anterior extent of the
bone ﬂap may be varied, depending on the extent of
frontal damage and blood clot seen on the CT scan. A
subtemporal craniectomy is useful as a pressure valve.
Indeed, it has been demonstrated that a large subtem-
poral craniectomy can make it easier to control intracra-
nial hypertension in situations where all other medical
means have failed (77). We routinely use the operative
ultrasound to rule out the presence of previously unde-
tected intracerebral hematomas or a growing mass lesion
on the opposite side of the brain (Fig. 11). The majority
of the patients with an acute subdural hematoma have
associated intracerebral contusions or hematomas.
Epidural Hematomas
Epidural hematomas are typically located in the tem-
poral region and often result from tearing of the middle
meningeal vessels secondary to a temporal bone frac-
ture. Venous epidural hematomas may occur as a result
of a skull fracture or an associated venous sinus injury.
They generally tend to be smaller and are associated with
a more benign course. These may, in certain cases, be
safely treated nonsurgically, especially when they pres-
ent to the neurosurgeon several hours after the initial
injury. However, most epidural hematomas represent a
surgical emergency and should be evacuated as rapidly
as possible. Because the brain underlying an acute epidu-
ral hematoma is generally fairly normal, every effort
should be made to relieve the pressure as soon as possible
to avert any brain damage. The outcome from surgery
for an epidural hematoma is very closely related to the
patient's clinical condition prior to surgical evacuation.
If the clot is large, or if there is any doubt as to the extent
of underlying brain damage, the standard large craniot-
omy ﬂap is recorrnnended. In instances where the epidu-
ral hematoma is clearly localized to one region and there

A. Initial Incision
B. Temporal Decompression
C. Completed
Incision
is no associated subdural blood seen on the CT scan, a
smaller modified craniotomy ﬂap may be used.
Intracerebral Hematomas
Brain injury is often an evolving phenomenon. The
CT scan at admission frequently deteriorates over the
HEAD INJURY / 259
FIG. 10. Evacuation of an acute subdural he-
matoma: (A) In instances when there is evi-
dence of rapid neurological deterioration sec-
ondary to a hemiation syndrome, temporal
decompression is recommended as the first
step. An incision is made just anterior to the
ear and taken down to the zygoma, which
marks the floor of the temporal fossa. (B) A
burr hole is made, followed by a quick craniec—
tomy. The dura is incised and as much of the
blood clot as possible is aspirated. (C) The in-
cision is then extended upwards to form a
large question mark, the medial extent of
which follows the midline. (D) Additional burr
holes are then made, with the medial ones 1 .5
cm off the midline to avoid injury to the major
venous structures and granulations. The ante-
rior burr hole is placed above the frontal sinus,
the size ofwhich can be estimated from preop-
erative radiographs. (E) The dura can be
opened with a Y—shaped or X—shaped incision,
with a flap being based on the superior sagit—
tal sinus. (F) The subdural hematoma is gently
evacuated with suction, irrigation, and other
mechanical means. Sources of bleeding are
identified and cauterized. Contused brain is
debrided, and pial edges are carefully cauter-
ized. The ultrasound is used to rule out the
presence of occult intracerebral or contralat—
eral hematomas.
next several days, resulting in what have come to be
known as delayed traumatic intracerebral hematomas
(DTlCHs) (Fig. 12). This interesting clinical phenome-
non of uncertain pathogenesis and debatable prognostic
significance has been discussed by several authors (78-
84). Contusions are most often located on the anterior
and inferior surfaces of the frontal and temporal lobes.

260 / CHAPTER 12
Observe_ brain swelling and
rule out intracerebral and
contralateral hematomas
Debride frontal and with ultrasonography
temporal contusions
Look_ for bleeding from
draining veins
Protect vein of Trolard
Look for residual hematomas
beyond limits of ﬂap
Protect vein of Labbe
e Baylor Cotege at Mecicine 1990
Contusions measuring larger than approximately 2 cm
should generally be debiided if they are causing a signifi-
cant mass effect. Care should be taken to stay within
necrotic brain and to avoid damaging surrounding nor-
mal tissue. This distinction cannot always be easily made
and requires some nicety of clinical judgment. As a gen-
eral rule, debridement of the left temporal lobe is per-
formed more conservatively than debridement on the
right side, particularly in right—handed patients.
FIG. 1 1 . Precautions to be taken during acraniot—
omy for subdural hematoma.
Posterior Fossa Hematomas
These are fortunately less Common than supratentor—
ial lesions. In general, an aggressive surgical approach is
advocated in the management of these lesions, because
these patients can deteriorate very rapidly. A patient
with a posterior fossa hematoma Could deteriorate from
a responsive state to a comatose condition within a mat-
ter of minutes. Furthermore, because it generally takes
FIG. 12. Delayed traumatic intracerebral hematomas: (A) Non—enhanced CT scan of a patient with a
severe head injury at admission. (B) Repeat study two days later shows extensive delayed traumatic
intracerebral hematomas in both frontal lobes.

FIG. 1 3. Depressed skull fracture. CT scan of a right parietal
depressed fracture showing the overlying scalp hematoma
that can mask the degree of depression. Note the obvious
compromise of the underlying brain tissue.
longer to evacuate such a lesion and because the brain
structures that are located in the posterior fossa are so
much more critical to the vital functions, the surgeon
does not have much leeway in terms of time. A prone or
three—quarter prone position with a Mayfield headholder
is generally used.
Depressed Fractures
A skull fracture is considered signiﬁcantly depressed if
the outer table of the skull lies below the level of the
HEAD INJURY / 261
inner table of the surrounding bone. Sometimes such
depression may not be evident on plain x—rays, but it is
usually clearly seen on the CT scan (Fig. 13). Depressed
skull fractures can be either closed or compound. Most
closed depressed fractures occur in young children and
may be of the "ping pong ball" variety. The most com-
mon indication for surgery in such cases is cosmetic,
especially with frontal fractures. In compound depressed
fractures, the wounds are often dirty and contaminated.
Often skin, hair, or other foreign debris will be wedged
between the depressed bone fragments, even when the
wound looks relatively clean from the outside. There-
fore, except in the simplest of injuries, closing of such
fractures in the operating room is recommended. Often
a dural laceration underlies the fracture, and great care
should be taken to close this primarily. However, the
presence of an intact dura does not necessarily preclude
an underlying brain contusion. A preoperative CT scan
is therefore very useful in defining the extent of the sur-
gery required. It is generally considered acceptable to
replace bone fragments at the craniectomy site. The post-
operative infection rate with such replacement is re-
ported to be less than 5 percent (85). Depressed fractures
overlying major venous sinuses (Fig. 14) are harder to
treat. The issues relating to sinus injuries are brieﬂy dis-
cussed in the next section.
Penetrating Head Injuries
In the United States, penetrating head injuries are
most commonly secondary to gunshot wounds. In the
civilian setting, these are overwhelmingly secondary to
handguns. The severity of the head injury can vary with
the caliber of the weapon, the distance from which it was
fired, the ammunition used, and the trajectory of the
FIG. 1 4. Depressed skull fracture overlying the superior
sagittal sinus. When dealing with such injuries, the sur-
geon must be prepared to deal with massive, sudden
blood loss. The anterior third of the sinus may be ligated,
but every effort should be made to repair the posterior
two—thirds.

262 / CHAPTER 12
bullet Plain x—rays of the skull and a CT scan are invalu-
able in planning management in any given case. In the
military setting, high—velocity injuries from riﬂes are also
encountered, and these are certainly more devastating.
In addition, military wounds are often secondary to
shrapnel, which are usually of lower velocity because of
their irregular shape. Penetrating injuries can also be sec-
ondary to a variety of nomnissile objects, such as knives
or scissors, which cause local brain damage but little dif-
fuse "shock" injury.
The surgical approach to penetrating head injuries
(Fig. 15) is somewhat different than that used with closed
head injury. If a penetrating object is still in place and is
projecting out of the skull, it is left in place until the
patient is completely ready fo" surgical intervention.
This is done to avoid torrential bleeding, which may en-
sue after removal of such an object. Unlike surgery for
closed head injury, surgery for penetrating head injuries
usually involves making a limited cranial opening. The
scalp opening may be just a linear or S—shaped extension
of the entrance wound or a limited U—shaped ﬂap. The
opening into the cranium may be via a craniectomy, or,
if the surgeon prefers it, by a small craniotomy. The
main purpose of the surgery is to debride the necrotic
brain, remove bone fragments and other foreign bodies
from the brain parenchyma, arrest bleeding, evacuate
any hematoma, and finally to secure water—tight closure
of the dura and scalp. Often, bullet fragments have pene-
trated into the other side of the brain. Unless these are
easily accessible, surgery does not necessarily need to be
taken on the opposite side in order to remove the bullet.
It was standard Army policy to reoperate on patients
whose cranial gunshot wounds had been closed at front-
line hospitals, in order to remove all bone fragments.
However, the Vietnam Head Injury Study demonstrated
by CT that the vast majority of such patients harbor
small bone fragments despite a second operation and do
not seem to demonstrate an increased incidence of com-
plications. Complete removal of such bone fragments is
not likely to be accomplished without sacrificing some
normal brain in the process. Therefore, it is now believed
that a reasonable degree ofdebridernent under antibiotic
cover is a safe and reasonable option (86). This has
been borne out by military experience in Lebanon as
well (87).
Venous Sinus Injuries
Venous sinus injuries are among the most difficult in-
juries a neurosurgeon has to face. Major sinuses can be
either ligatcd or reconstructed. It is generally true that
the anterior third of the superior sagittal sinus can be
safely ligated. but ligation of the posterior third is most
likely to produce massive venous infarction of the brain.
Ligation in the middle third has somewhat unpredict-
able effects, and ligation of the dominant transverse si-
nuses can also have disastrous effects. If an attempt is to
be made to repair a major venous sinus, the Kapp—Giel—
chinsky shunt can be a useful device (46). This is a typi-
cal vascular shunt, but it has inﬂatable balloons at both
ends. It can be used to maintain venous blood ﬂow while
the reconstruction is being planned or executed. It is of-
ten technically easier to use dural ﬂaps to oversew sinus
injuries. Other standard neurosurgical maneuvers using
pressure, gelfoam, Surgicel®, and other hemostatic
agents may be invaluable in controlling the bleeding.
The use of a rapid autotransfusion unit can limit the
amount of blood transfusions required, thus reducing
the pressures on the blood bank and minimizing the risk
of blood transfusions for the patient.
THERAPEUTIC AGENTS
Advances in the "intensivist" approach to acute ill-
ness have resulted in more scientific and thorough meth-
ods of managing head—injured patients, with their multi-
ple associated problems. Aggressive management of
such problems is, logically, likely to reduce the incidence
of secondary insults. One would expect that such an ap-
proach can reduce mortality owing to medical complica-
tions, and this has been the experience in well—docu—
mented prospective series (29,73,88,89). These studies
have also shown that the majority ofpatients "saved" by
such aggressive management do not join the ranks of the
severely disabled or vegetative but actually go on to be-
come only moderately disabled or to make a good recov-
ery. Thus, a systematic and intensive approach to the
management of severe head injury is effective enough to
justify the corrnnitment of additional resources in this
direction (90).
Unfortunately, our experience with drug therapies has
so far been less than satisfactory. Owing to the irrevers-
ibility of some of the damage and to the complexity of
the pathogenesis of brain injury, it seems unlikely that a
penicillin—like wonder—drug will be found. It seems more
likely that a combination of several agents and interven-
tions, each with its small beneficial effect, will make a
significant cumulative impact on outcome. These small
effects of individual agents arc difficult to demonstrate
conclusively given the nonhomogeneity of head—injured
patients, the large number of patients required to com-
plete such clinical trials, and the prohibitive cost. With
this background in mind, we can brieﬂy review the drugs
commonly in use and speculate upon other possibilities.
Anticonvulsants
The use of prophylactic anticonvulsants in patients
with severe head injury remains controversial (91 -98). A
survey of neurosurgeons in 1972 revealed that 40 per-

A. Small Scalp Flap
F. Dural Closure
and Repair
Powder burns in
‘cIose—range injury
D. Debridement of Bullet Tract
B. Craniectomy
, Bullet entry site
FIG. 15. Surgery for penetrating head in-
jury. The approach to penetrating head inju-
ries is somewhat different from that for
closed head injuries because the damage
tends to be more focal. The entry and exit
sites are treated similarly. (A) A small linear
or S—shaped incision incorporating the entry
wound is recommended. (B) A craniectomy
is performed at the entry site in the skull. (C)
The dura is opened in a cruciate fashion. (D)
Blood, necrotic brain, bone and bullet frag-
ments along the path of injury are debrided.
(E) Hemostasis is secured with bipolar cau-
tery and hemostatic agents. (F) Dural repair
is completed using pericranium or |yophi—
lized dura as needed.

264 / CHAPTER 12
- cent of them did not use these drugs routinely either
—because they were uncertain of the indications or be-
cause the risk was considered too low to justify treatment
(93). Jermett conducted a major study of posttraumatic
epilepsy and found this complication to occur in about 5
percent of all patients admitted to the hospital with non-
missile head injuries and in 15 percent of those with se-
vere head injuries (91). Three main factors were found to
be linked to a high incidence of late epilepsy (Table 9);
(1) early seizures, occurring within the first week: (2) an
intracranial hematoma; and (3) a depressed skull frac-
ture. It has been suggested that prophylactic treatment
with phenytoin initiated as early as possible (within 24
hours) might prevent the development Of an epilepto—
genic focus. However. Young and associates" random-
ized, double—blind, placebo—controlled studies showed
that prophylactically administered phenytoin did not
prevent either early or late posttraumatic seizures (94-
96). In these studies, plasma concentrations were main-
tained between 10 and 20 jig/ml. Although the authors
caution that maintaining higher drug levels could have
altered the results of the study, they recommend using
anticonvulsants only after a patient has had a seizure.
McQueen and coworkers however, pointed out that be-
cause of the low incidence of posttraumatic seizures (7%
at one year; 10% at two years), randomized clinical trials
must include about 1200 patients to be conclusive (97).
If so, all reported trials have been too small (by a factor of
at least six). The weight of evidence therefore currently
supports the routine use of anticonvulsants in high—risk
groups (as denned above), but not necessarily in all pa-
tients with head injury. Temkin and associates recently
reported results from a double—blind study in which 404
severely head—injured patients randomly received phen-
ytoin or placebo beginning within 24 hours of injury and
continuing for one year (98). They found that phenytoin
reduced the incidence of seizures during the first week
after injury, but not thereafter.
Our present practice is to use phenytoin (500 mg intra-
venously over 10 minutes) in the emergency room in all
patients with severe head injury. Doses are adjusted to
achieve therapeutic blood levels. According to the find-
ings of Young and associates, aiming for blood levels
higher than 15 to 20 /ug/ml may be justified (95,96). The
entire requirement may be taken as a single daily dose
(99). There are no hard and fast rules for when to stop
anticonvulsants, although the recent Temkin study
TABLE 9. Main factors associated with late epilepsy3
1 . No early epilepsy 3%
Early epilepsy 25%
2. No intracranial hematoma 3%
Hematoma 35%
3. No depressed fracture 3%
Depressed fracture 17%
' Adapted from reference 261 , with permission.
would justify stopping treatment after the first week in
most cases (98). The EEG is not generally contributory
in making this decision. The drugs should be tapered off
gradually, rather than stopped abruptly (100). There is
some evidence to suggest that carbamazapine (Tegre—
tol®) may be preferable to phenytoin for long—ter1n use
because of improved performance on tests of cognitive
function (101).
Steroids
Although corticosteroids have not been conclusively
shown to be effective in head injury, many neurosurg-
eons use them in severe cases. Two studies have sug-
gested that very large doses of steroids may reduce the
mortality rate in severe head injury (102,103). However,
closer examination of the study done by Faupel and as-
sociates reveals that the reported decrease in mortality
was achieved as a result of a large increase in the number
of vegetative survivors (102). If the outcome groups are
divided into good outcome (good recovery and moder-
ately disabled) and poor outcome (severely disabled, veg-
etative, and dead), there was no statistical difference be-
tween the steroid— and placebo—treated groups. Gobiet
and associates compared a high—dose dexamethasone
group (96 mg/day) with a conventional dose group (16
mg/day), and a placebo group. There was no statistical
difference in mortality between the high—dose and the
placebo group, but this study was limited by being non-
blinded and sequential (all patients in one year received
the same treatment) (103).
One must, however, beware of a type H error and of
missing actual beneficial effects because of inadequate
sample sizes (104). A study by Saul, Ducker, Salcman,
and Cairo suggests that steroids may help certain sub-
groups of patients with head injury (105). However, the
literature contains several articles in support of the view
that traumatic brain injuries, in contrast to brain tu-
mors, do not respond well to steroids, either in terms of
ICP control or in terms of improved outcome (106-
109). Most recently, the NASCISII study, which showed
a beneficial effect of very high—dose methylprednisolone
in spinal cord injury, may rekindle interest in the appli-
cation of steroids for head injury (110).
Mannitol
This agent is now widely employed to reduce intracra-
nial pressure. The commonly used preparation is a 20
percent solution of mannitol (mw 180). It has been gener-
ally believed that marmitol establishes an osmotic gra-
dient between the plasma and the brain, resulting in a
shift of water out of the brain and, therefore, in a fall in
ICP. Proving this has been somewhat difficult (111), how-
ever, and there certainly may be other mechanisms by

which rnannitol lowers ICP (112-114). Serum os1nolal-
ity should not be allowed to go above 320 osmoles/liter,
if possible, in order to avoid systemic acidosis and renal
failure (115). Views relating to the appropriate dose of
mannitol vary (116). The most widely accepted regimen
is 1 to 2 g/kg given intravenously as quickly as possible.
If a patient shows evidence of neurological deterioration
or tentorial herniation, we administer mannitol rapidly
en route to the CT scanner. The patient should have a
Foley catheter in place at this point, as diuresis can be
expected. With continued use, intravascular mannitol
equilibrates with the brain and progressively higher
blood levels are required to elicit a response.
Thirty percent urea (mw 60) and 10 percent glycerol
(mw 92) were previously used interchangeably with
mannitol in the chronic setting. These agents have
smaller molecular weights and tend to equilibrate more
rapidly with the brain. Urea is also associated with a high
incidence of hemoglobinuria and severe sloughing of the
skin if it infiltrates (117). Wald and McLaurin have re-
ported on their experience with oral glycerol in head in-
jury patients (118). However, oral agents should not be
considered in the treatment of an acutely injured patient
for obvious reasons.
Lasix
Certain authors have reported the use of furosemide,
either alone or in conjunction with mannitol, in head
injury (1 19) and in other states. Schcttini, Stahurski, and
Young demonstrated that diuresis could be enhanced by
the combined use of mannitol and furosemide in neuro-
surgical patients, with more pronounced and consistent
brain shrinkage (120). In their study, a peak diuresis of
17 ml/min was reached within 30 minutes of mannitol
administration, with a fall to 4 rnl/min during the next
70 minutes. By contrast, during an identical time course,
combined mannitol-furosernide infusion yielded an ini-
tial water excretion rate of 30 ml/min, followed by a
further increase to 42 ml/min, and then by a decline
to 17 ml/min. The patients were given 1.4 g/kg of man-
nitol i0.3 mg/kg of furosemide. The only adverse effect
noted with combined therapy was accelerated electrolyte
loss, which had to be corrected. These findings were con-
firmed by Wilkinson and Rosenfeld (121).
Sodium Bicarbonate
Along with hypoxemia, a low arterial pH on admis-
sion, indicating systemic acidosis, is not uncommon. If
the patient has been in shock, this is usually lactic acido-
sis. If the arterial CO2 tension (Pacoz) is high, it indicates
a mixed respiratory and metabolic acidosis. The acidosis
should be corrected, and sodium bicarbonate may be
given in a dosage of 1 mEq/kg every 10 minutes or so
HEAD INJURY / 265
until it is resolved. It should, however, be remembered
that reversal of mild acidosis can occur quickly and spon-
taneously when ventilation and perfusion arc restored by
intubation and normalization of systemic arterial pres-
sure. As a general rule, an arterial blood pH under 7.1
indicates severe metabolic acidosis and calls for the use
of sodium bicarbonate. At this level, cardiac function is
adversely affected by the acidosis (122). The dosage may
be roughly estimated by the following formula: dosage of
sodium bicarbonate (mEq) equals 0.2 times the body
weight (kg) times 27 mEq/1 minus the patient's serum
bicarbonate level. Half the calculated dose is given ini-
tially, and subsequent doses are administered after re-
peat pH determinations.
When massive blood transfusions are given to patients
in severe shock, an ampule of sodium bicarbonate
(about 45 mEq) should probably be given with every two
to three units of whole blood in order to correct for the
acidity of banked blood.
Tris-hydroxy-methyl-aminomethane (THAM)
It has been demonstrated that brain injury is asso-
ciated with metabolic acidosis as reﬂected in high CSF
lactate levels (123.124). It has also been shown that pa-
tients with higher CSF lactate levels have a worse out-
come and that those with a deteriorating course gener-
ally show a progressive fall in CSF pH from 7.3 to 7.2
owing to lactic acidosis (125,126). Several groups have
examined the role of acidosis in the pathogenesis of neu-
ronal damage (127-129). DeSalles, Kontos, and Becker
recently studied the prognostic significance of ventricu-
lar CSF lactate in severe head injury (130) and noted
lower pH values in the brains of three patients who un-
derwent surgery for acute subdural hematomas (131).
THAM is a buffering agent that penetrates the CNS and,
therefore, is theoretically superior to sodium bicarbonate
for the treatment of CNS acidosis. Akioka and col-
leagues, using a dog epidural balloon model, demon-
strated a beneficial effect of THAM on ICP (132). This
was confirmed by Gaab and associates using a cold—le-
sion edema model in rats (133). Subsequently, Rosner
and Becker reported a beneﬁcial effect of THAM in a cat
ﬂuid percussion model (134). They found that THAM
was associated with reduced morbidity and mortality as
well as lowered ICP after percussion injury. A clinical
trial is now being conducted with this agent at the Medi-
cal College of Virginia (H.F. Young, personal communi-
cation).
Barbiturates
Several studies have demonstrated the protective ef-
fect of barbiturates on the brain in cerebral anoxia and
ischemia (135-137). It has also been documented that
barbiturates are effective in reducing intracranial pres-

266 / CHAPTER 12
sure (135-139). However, two randomized prospective
studies—one from Richmond (140) and the other from
Toronto (141)—indicated that no benefit was derived
from high—dose barbiturates in terms of either ICP con-
trol or outcome. In both of these studies, barbiturates
were given as the initial therapy. In arecently completed
prospective randomized multicenter trial in which high-
dose pentobarbital was given after all conventional
means of ICP control had failed, a clearly beneﬁcial ef-
fect was noted on ICP levels (142). Because of the study's
cross—over design, no conclusion could be made regard-
ing the effect ofpentobarbital on outcome. However, it is
evident that barbiturates should be reserved for a small
subset of patients who have failed all other forms of ther-
apy for intracranial hypertension.
One protocol for pentobarbital therapy is to give a
loading dose of 10 mg/kg over 30 minutes and 5 mg/kg
every hour for three hours, followed by a maintenance
dose of 1 mg/kg/hr adjusted to achieve a serum level of 3
to 4 mg%. Hypotension is often a limiting factor.
Naloxone
Naloxone, the narcotic antagonist, has been shown to
reverse hypotension associated with head injury in cats
(143). It is conceivable that a release of endogenous
opiates may be responsible for this postconcussive hypo-
tension (144). Few data either support or refute the value
of this agent in head injury. The recent NASCISII study
showed no beneficial effect of naloxone in spinal cord
injury (110).
Short—Acting Hypnotics
Because ofthe tendency ofbarbiturates to cause hypo-
tension and to prolong recovery after cessation, there has
been a search for shorter—acting anesthetic agents to con-
trol intracranial hypertension. Althesin, an intravenous
steroidal anesthetic agent, although never approved for
use in the United States, was popular in Britain for a
while before its manufacture was discontinued because
of concerns relating to anaphylaxis (145). Etomidate ap-
pears to be a satisfactoiy alternative for anesthetic use,
but no data are available on long—term use in head—injury
patients (145).
Hyperb aric Oxygen
Although Sukoff and Ragatz reported in 1981 that hy-
perbanc oxygen therapy (HBO) can reduce ICP and may
be of value in the treatment of traumatic cerebral edema
(146). this therapeutic modality is not widely used be-
cause, in general, results have been less than impressive.
Fuithermore, this treatment does call for investment in a
hyperb aric chamber and is labor—intensive when dealing
with critically ill patients. However, these authors did
demonstrate a consistent reduction in ICP during expo-
sure to hyperbaric oxygen at two atmospheres pressure
and reported neurological improvement. Recently,
Rockswold, Ford, Bergman, and Anderson reported the
results of their prospective randomized study of HBO in
severe head injury (147). They found that although HBO
signiﬁcantly improved survival in patients with a GCS
score of 4 to 6, it did not improve the percentage of
patients making a good recovery.
Free Radical Scavengers
The role of oxygen radicals in the pathogenesis ofhead
injury has received much recent attention (148). Schet—
tini, Lippman, and Walsh demonstrated a dramatic re-
duction in mortality in a dog epidural balloon compres-
sion—deco1npression model with the use of native
superoxide dismutase (SOD) after injury (149). Because
of this study and other experimental data, SOD in its
native as well as its conjugated form (PEG—SOD) is
currently undergoing early clinical testing.
INTRACRANIAL PRESSURE
MONITORING AND CONTROL
Several pathological processes that affect the brain can
cause elevation of intracranial pressure. In turn, intracra-
nial hypertension can have consequences that adversely
affect the patient's outcome. Thus, elevated ICP not only
indicates the presence of a problem but can often contrib-
ute to it. Continuous monitoring of ICP was pioneered
by Guillaume and J army in 1951 (150) and was applied
systematically to head—injured patients by Lundberg in
1960 (151). Since the early 1970s, there has been increas-
ing interest in ICP monitoring and a progressive evolu-
tion of related technology. ICP monitoring is now selec-
tively applied to severely head—injured patients in
virtually all major neurosurgical centers in the United
States.
Basic Physiology
Normal ICP in the resting state is approximately 10
mm Hg (136 mm H2O). As abroad generalization, pres-
sures over 20 mm Hg are considered abnormal, and
pressures over 40 mm Hg can be categorized as severe
elevations. It has been clearly demonstrated that higher
ICP following head injury is associated with a poorer
outcome. CSF is formed mainly in the choroid plexuses
of the lateral and third ventricles, and the daily produc-
tion of CSF is approximately 500 ml. Approximately
150 ml of CSF is present within the craniospinal axis.

Normal State - ICP Normal
Compensated State"- ICP Normal
Venous
Volume
Uncompensated State - ICP Elevated
The Monro-Kellie Doctrine
This is a simple yet vitally important concept relating
to the understanding of ICP dynamics (152,153). It
states that the total volume of intracranial contents must
remain constant. This is fairly obvious because the cra-
nium is essentially a non—expansile box. Thus, if Vde—
notes volume,
VBrain + Vcfs + Fglood + FMaSS = Constant
As the size of an intracranial mass lesion, such,as a
hematoma, increases, there is a compensatory squeezing
out of CSF and of venous blood (Fig. 16). The intracra-
nial pressure initially remains normal. However, eventu-
ally no more CSF or venous blood can be eliminated,
Volume of Mass
FIG. 17. Pressure—vo|ume curve. The pressure—vo|ume rela-
tionship described in Figure 1 6 is shown schematically in this
graph. Every effort should be made to keep the patient in the
flat portion of the curve rather than to try to salvage the pa-
tient once the point of decompensation has been reached.
HEAD INJURY / 267
FIG. 1 6. The Monro—Kel|ie doctrine: intra-
cranial compensation for expanding
mass. The volume of ihe iniracranial con-
tents remains constant. If the addition of
a mass such as a hematoma results in
CSF the squeezing out of an equal volume of
CSF and venous blood, the ICP remains
normal. However, when this compensa-
tory mechanism is exhausted, there is an
exponential increase in ICP for even a
small additional increase in the volume of
the hematoma.
J.75CC
and the compensatory mechanisms are no longer effec-
tive. At this point, intracranial pressure begins to in-
crease exponentially with even a small additional in-
crease in the size of the intracranial mass. The
pressure—volu1ne curve illustrates this phenomenon (Fig.
17). It is obvious from studying this curve that a normal
intracranial pressure does not necessarily preclude the
presence of a mass lesion. In fact, the ICP is generally
within normal limits until a patient reaches the point of
decompensation and enters the exponential phase of the
pressure—Volume curve. The ICP number per se does not
initially give any indication of where along this curve a
patient is.
Brain Elastance
In order to better understand ICP dynamics, the con-
cept of brain elastance was introduced. This is denned as
the change in ICP resulting from a unit change in intra-
cranial CSF volume. It is usually quantified in terms of
the "volu1ne—pressure response" (VPR), which is defined
as the immediate rise in intracranial pressure resulting
from an injection of 1 ml of fluid over 1 second (154). In
a normal subject, the VPR is 0 to 2 mm Hg/ml. Values of
3 to 4 mm Hg/n11 are often seen after surgery for head
trauma, and Values of 10 to 20 111111 Hg/ml are usually
indicative of the presence of a mass lesion.
Pressure- Volume Index
Another measure of intracranial compliance is re-
ferred to as the pressure—Volu1ne index (PVI). This is de-
nned as the Volume of ﬂuid that would theoretically have
to be injected into the craniospinal axis to produce a
10-fold increase in intracranial pressure (155). Clini-

268 CHAPTER 12
Cally, this is a calculated figure based on the following
formula:
where P, is the initial ICP and P2 is the final ICP after an
injection of, for example, 1 ml of ﬂuid. Normal PVI is
26 i 4 ml; values of 13 ml or less aft considered clearly
indicative of markedly compromised intracranial com-
pliance (156). Although VPR and PVI are not yet
widely used in the management of neurosurgical pa-
tients, it is important to understand their basis and sig-
nificance (157).
Cerebral Perfusion Pressure
Cerebral perfusion pressure (CPP) is the mean arterial
blood pressure minus intracranial pressure. Perfusion
pressures of less than 80 mm Hg are generally associated
with a poorer outcome following head injury (158). The
use of CPP rather than ICP alone has been recom-
mended by some for the routine monitoring of patients.
Rosner and Daughton have advocated a method of man-
agement of head injury based on maintenance of CPP
(159). Simard and Belleﬂeur have suggested that the po-
tentially deleterious effects of too great a perfusion pres-
sure following head injury may not have receiyed due
recognition (160).
Autoregulation
The phenomenon of autoregulation tends to maintain
a fairly constant cerebral blood ﬂow (CBF) between
mean blood pressures of 50 and 160 mm Hg. Below 50
mm Hg the CBF declines steeply, and above 160 mm Hg
there is a passive dilatation of the cerebral vessels and an
increase in CBF. It has been shown that autoregulation is
often severely disturbed in the head—injured patient
(161). Because increases in cerebral blood volume can
contribute significantly to intracranial hypertension
(162), it is as important to avoid systemic arterial hyper-
tension as it is to avoid shock in the severely head—in-
jured patient. Although the data are not available regard-
ing the optimal level at which blood pressure should be
maintained, an overly aggressive correction of moderate
hypertension or less than prompt correction of hypoten-
sion can be disastrous, especially in elderly patients.
Technical Aspects
ICP Measurement in Diﬁerent Planes
ICP can be monitored in several different planes
(163). These are given in the following list along with the
commonly available monitoring devices that can be
used:
- Lateral ventricle: ventricular Catheter, pressure—sensi—
tive fiber—optic device
- Intraparenchymalz pressure—sensitive fiber—optic de-
vice
- Subdural/subarachnoid: hollow bolt, catheter, pres-
sure—sensitive fiber—optic device
- Epidural: pressure—sensitive capsule
- Anterior fontanel: tonometry
ICP Recording Devices
Three major types of devices are used for ICP moni-
toring. The intraventricular catheter remains the gold
standard. However, other devices are available and dem-
onstrate varying degrees of accuracy. The commonly
available devices include (1) catheters (intraventricular
or subdural); (2) hollow adapters (screws, bolts), such as
the Richmond, Philadelphia, Leeds, and Philips; and (3)
pressure—sensitive Capsules such as the Camino fiber—op-
tic and Ladd devices.
We use ventricular catheters in ahnost all cases. For
the few instances in which the ventricles cannot be suc-
cessfully cannulated, we used to use subarachnoid (Rich-
mond) bolts, but over the last couple of years we have
been using the Camino fiber—optic device. Nevertheless,
the vast majority of our patients are still monitored
through a ventriculostomy. The advantages and disad-
vantages of these devices are shown in Table 10.
Value of ICP Monitoring
Although some debate persists regarding the indica-
tions for ICP monitoring in various neurosurgical condi-
tions, it is generally accepted that the technique can be
Valuable in the monitoring and treatment of the severely
head—injured patient. ICP data can be used in three dif-
ferent ways:
1. As a diagnostic adjunct:
- Elevated ICP and midline shift on an air ventriculo-
gram serve as useful indicators of a mass lesion if a
CT scanner is not immediately available.
- ICP data facilitate early diagnosis of a developing
mass lesion.
- Data allow therapy to be initiated before irrevers-
ible neurological damage occurs, especially in se-
dated or paralyzed patients in whom the clinical
exam is difficult to follow.
2. As a therapeutic adjunct:
° Ventriculostomies are useful for CSF drainage,
which can lower ICP, at least temporarily.
- Knowledge of the ICP takes the guesswork out of
therapy. ICP ﬂuctuates greatly, and the response of
different patients to different maneuvers to lower
ICP is very unpredictable. Empirical therapy with

HEAD INJURY / 269
TABLE 10. Features of certain ICP monitoring devices
Advantages
Disadvantages
Ventricular catheter 1. Gold standard of accuracy
2. Allows drainage of CSF for
- ICP control
- CSF sampling
- Monitoring infection
<<
Subarachnoid bolt . Does not invade brain
2. May have a lower infection rate
. Sometimes difficult to cannulate ventricle
2. Requires f|uid—filled column, which can
get blocked by air bubbles and debris
3. Artifact from tube movement
4. Needs repositioning of transducer level
with change in head position
1. Blocking of port by swollen brain may
cause artificially low readings
3. No need to cannulate ventricle 2. Same as 3 and 4 under Ventricular
Fiber—optic device 1 .
intraparenchymally, or
intraventricularly
2. Minimal artifact and drift
3. High resolution of waveform
. No need to reposition
transducer with change in
head position
Can be placed subdurally,
catheter
1. Inability to check calibration once
inserted, unless a ventriculostomy is
used simultaneously
2. Fiber breakage
agents such as mannitol, without a means of moni-
toring response, is therefore not optimal.
3. As a prognostic tool:
- In general terms, ICP trends can be used together
with clinical signs in judging prognosis.
Whether ICP monitoring per se improves outcome
from head injury is a rather controversial issue that has
been debated in neurosurgical conferences, as well as in
courts of law. Trying to prove this is somewhat akin to
trying to demonstrate that continuous blood pressure
monitoring improves outcome from cardiac surgery. In
view of the numerous variables involved, it is very diffi-
cult to design a study that would conclusively answer this
question. There has been no randomized study, and
such a study may be difficult to justify. However, certain
large, well—documented, nonrandomized studies have
indicated that as part of a program of intensive care, the
monitoring and control of ICP may be associated with
improved outcome in patients with severe head injury
(73,88,89). There is no doubt that ICP monitoring has
greatly added to our understanding of intracranial dy-
namics and helped put the management of patients on a
more scientific basis. We monitor ICP in all head injured
patients who have a significantly altered level of con-
sciousness and find the data so derived to be very valu-
able in patient management. However, facilities for ICP
monitoring are not universally available, and it is cer-
tainly feasible to use alternative management strategies
(164,165).
Indications for ICP Monitoring
Head injury is the most common indication for ICP
monitoring. As a general rule, patients who are able to
follow simple commands do not need to be monitored.
They may satisfactorily be followed clinically. In pa-
tients who are unable to follow commands and have an
abnormal CT scan, the incidence ofintracranial hyper-
tension is high (53 to 63 percent) and monitoring is
warranted (30). Severely head—injured patients with nor-
mal CT scans generally have a low incidence ofintracra-
nial hypertension (13 percent), unless they have two or
more of the following adverse features at admission (30):
1 . Systolic blood pressure less than 90 mm Hg
2. Unilateral or bilateral motor posturing
3. Age over 40
ICP should be monitored in patients with cerebral
contusions who are unable to follow simple commands.
If the pressure rises and persists over 25 to 30 mm Hg,
surgical debridement is usually indicated. Clinicians
should be aware that ICP is not always elevated in the
presence of an intracranial process. This is particularly
true of temporal lobe lesions that can cause tentorial her-
niation in the absence of ICP elevation.
Treating Raised ICP
There has been some debate as to what constitutes
elevated ICP. Initially, it was decided somewhat arbi-
trarily to treat intracranial pressures of greater than 25
mm Hg in patients with severe head injury. Since then,
this figure has been moved down by other groups to 20
and then to 15 mm Hg. Transient elevations of ICP asso-
ciated with patient manipulation such as suctioning,
turning, or coughing do not constitute adequate reason
for treatment. The following step—wise approach to ICP
elevation is suggested:

270 CHAPTER 12
Ensure optimal body and neck position. It is generally
accepted that the neck should be in a neutral position
to facilitate venous drainage. Turning the neck to an
extreme position can result in reduced venous out-
ﬂow and elevation of intracranial pressure. The opti-
mal degree of head elevation;remains somewhat con-
troversial. Though it has been generally believed that
raising the head of the bed was a uniformly useful
maneuver, certain authors argue that this has to
be individualized and that head elevation may in
fact adversely affect cerebral perfusion in certain
cases (159).
2. Check calibration. Before more involved steps are
taken to treat intracranial pressure, one must cali-
brate the monitoring system and make sure that the
readings are not artifactual.
3. Check serum Na+ and ABGs. Hyponatremia is a
common problem in neurosurgical patients, often as
a result of SIADH. Hyponatremia should be treated
aggressively in these patients because it contributes
dramatically to brain swelling. Hypercarbia can also
result in brain swelling secondary to vasodilitation.
We used to use hyperventilation (down to a Pcoz of
25 mm Hg) as a routine measure to treat patients with
potential brain swelling. Recent studies, however, in-
dicate that hyperventilation over a period of time
may contribute to cerebral ischemia owing to vaso-
constriction (H. F. Young, personal communication).
We therefore use this modality only when necessary,
and then for as short a time as needed to keep intracra-
nial pressure within normal limits.
4. Rule out seizures. Although they are not a common
occurrence, subclinical seizures may result in unex-
plained increases in intracranial pressure.
5. Rule out mass lesions with a CT scan. Elevated ICP is
a sign of problems and should not be considered a
diagnosis in and of itself. Hence, if the aforemen-
tioned measures do not resolve the ICP problem, a
CT scan of the brain should be obtained to make sure
there is no developing mass lesion. This cannot be
emphasized enough.
6. Hyperventilate to a Pcoz of around 25 mm Hg. See
item 3 in this list.
7. Drain CSF via ventriculostomy. Intermittent drain-
age of CSF via the ventriculostomy is a very useful
method of controlling intracranial pressure. For this
reason a ventricular catheter is much more useful
than the other monitoring devices.
8. Administer mannitol (0.25 to 2.0 g/kg). This remains
our drug of choice for treating intracranial pressure
elevations. Although urea and glycerol have been
used in certain countries, mannitol is clearly the most
widely used agent in the United States. Its rapidity of
action, relative safety, and ability to be used intrave-
nously have contributed to its popularity.
9. Induce barbiturate coma. When all of the aforemen-
tioned measures have failed to control ICP, a barbitu-
rate coma may be considered. As a general guideline,
one should consider this when the ICP has remained
elevated over 25 mm Hg for 30 minutes or over 30
mm Hg for 15 minutes in spite of all of the preceding
therapies. The commonly used agent is pentobarbital
(Nembutal®) in a dose of 10 mg/kg as a loading dose,
over 30 minutes, 5 mg/Kg every 1 hour times 3, fol-
lowed by a maintenance dose of 1 mg/Kg/hr adjusted
to obtain a serum level of 34 mg% (142).
Complications of ICP Monitoring
The main risk of ICP monitoring is infection (30).
This incidence should be 5 percent or less. If monitoring
is conducted for less than three days, the infection rate is
virtually 0 percent. Beyond five days, the incidence of
infection begins to increase significantly. It is therefore
our practice to monitor for as short a duration as possi-
ble. If monitoring needs to be continued beyond five
days, the catheter is removed and a new catheter is in-
serted at a different site (166). The incidence of hemor-
rhage relating to the placement of an ICP monitoring
device is approximately 1 percent. The need for evacua-
tion of a catheter—related bleed is very uncommon. Fur-
thermore, because these devices are usually placed in the
frontal region, it is rare to have a neurological deficit
relating to catheter placement.
MANAGEMENT OF ASSOCIATED INJURIES
In a series of 100 patients admitted to the neurosurgi-
cal service of the Medical College of Virginia with severe
head injury, 57 had one or more major systemic injuries;
a total of 86 major injuries were recorded in these pa-
tients (10) (Table 4). Multiple injuries are most com-
monly associated with vehicular accidents (89 percent).
Falls and blows to the head account for only 11 percent
of the patients with multiple injuries. In view of the fre-
quency of other systemic injuries complicating the care
of the head—injured patient, a brief description of the
commonly encountered injuries and their management
is included.
Scalp Injuries
Scalp injuries are extremely common and are present,
to some degree, in almost all patients with a severe head
injury. The scalp consists of five layers (with the acro-
nym "SCALP"): skin, connective tissue (dense), apo-
neurosis (galea aponeurotica), loose connective tissue,
and pericranium. Its sensory nerve supply comes mainly
from the ophthalmic division of the trigeminal nerve an-
teriorly and the greater occipital nerve (C2) posteriorly.
Preauricularly, the auriculotemporal branch of the third

division of the trigeminal nerve follows the superﬁcial
temporal artery, and the area behind the ear is supplied
by the lesser occipital nerve from the cervical plexus (C2
to C3). The scalp has a very rich blood supply from five
major arteries: the supratrochlear and supraorbital
branches of the ophthalmic artery anteriorly, and three
branches of the external carotid—superficial temporal,
posterior auricular, and occipital—laterally and posteri-
orly. These vessels lie in the second (dense connective
tissue) layer of the scalp. For this reason, the vessels do
not retract when cut and tend to bleed profusely. The
galea aponeurotica is a dense, fibrous, nonelastic layer
that attaches to the frontalis and occipitalis muscles. It is
vitally important to achieve good repair of this layer in
the closure of scalp wounds. The loose connective tissue
layer can collect large hematomas following blows and
houses the emissary veins that pass through the bone
into the dural sinuses. Bacteria and septic emboli can
travel from the scalp into the cranium by way of these
verns.
Although large scalp lacerations are hard to miss, the
same is not true for contusions and small lacerations in a
comatose patient. In fact, even gunshot wounds can be
missed in the absence of a leading history, only to be
found on more careful examination after skull x—rays
provide the physician with the correct diagnosis. Thus, it
behooves the physician to examine the scalp in an in-
jured patient.
Scalp lacerations should be thoroughly cleaned, ex-
plored, debrided, and closed. Perhaps the most common
errors made in the closure of such wounds are inade-
quate shaving of hair and inadequate cleaning of hair,
bone, and other debris from the wound. Although the
scalp is relatively forgiving because of its rich vascular
supply, a sloppy repair job in the emergency room can
result in needless and sometimes serious morbidity.
After shaving around the wound and irrigating it with
saline, the physician, using gloves, must explore the scalp
laceration and make sure there is no underlying fracture
or penetrating injury. If the bone feels normal, or if x-
rays confirm that only the outer table of the skull is in-
volved, the wound can be irrigated with Betadine solu-
tion and saline, the edges debrided with a scalpel, and the
wound closed with nonabsorbable sutures (3-0 nylon).
The timing of scalp repair is not crucial. If the patient is
harboring a mass lesion, the scalp can be repaired after
evacuation of the mass. Ifnot, the repair can be accom-
plished in the emergency room or intensive care unit.
We prefer to use the operating room for more extensive
or complicated lacerations.
Scalp avulsions are less common but can be life-
threatening owing to the severe blood loss. The scalp is
usually avulsed through the loose connective tissue
layer. Direct microvascular anastomosis and replanta—
tion of the avulsed scalp is possible (167,168). For trans-
portation purposes, the avulsed scalp is cleaned with
HEAD INJURY / 271
normal saline, wrapped in damp sterile gauze, placed in
a watertight plastic bag, and transported on crushed ice.
There are many options for the design of skin ﬂaps for
closure of scalp defects. In general, the larger the ﬂap, the
poorer its chances of surviving. The base must be at least
as wide as or wider than the tip. Grafting procedures and
complex scalp reconstructions are generally performed
in conjunction with our plastic surgery colleagues. The
interested reader is referred to other sources for further
details (169-171).
Maxillofacial Injuries
A large proportion of patients admitted with multiple
trauma have evidence of maxillofacial injury (Table 11)
(172.173). In general terms, most facial injuries can be
handled semielectively several days after admission.
Even soft—tissue injuries can be repaired up to 24 hours
after admission in most cases. Exceptions to this rule
include acute airway obstruction secondary to retrodis—
placement of the tongue in bilateral mandibular fracture
and uncontrollable nasopharyngeal hemorrhage. How-
ever, despite the relatively low priority ofdefinitive facial
injury treatment, emergency room evaluation—both
clinical and radiological—should not be side—stepped.
This will allow the plastic or oral surgeon to complete a
preliminary evaluation either before or during other
"emergency" operations and to choose whether to per-
form any stabilizing or reparative procedures while the
patient is under anesthesia. The general principles of
management of these injuries are summarized here, but
the interested reader is referred to an excellent chapter
on this subject by Manson (174).
The Water's view (occipitomental) is the most valu-
able x—ray for studying the maxilla, the zygoma, and the
frontal sinuses. Oblique views of the mandible give the
TABLE 11. Classification of maxillofacial iniuries
soft—tissue injuries
A. Skin abrasions, punctures, lacerations, tattoos
B. Nerve injury—facial nerve branches
C. Parotid gland or Stensen's duct injury
D. Eyelid injury
E. Ear injury
F. Nasal injury
Bony injuries
A. Fractures of the upper third of the face
B. Fractures of the middle third of the face
1 . Nasal fractures
2. Maxillary fractures
LeFort l—transverse maxillary fracture
LeFort ll—pyramidal fracture
LeFort l||—craniofacial disjunction
3. Zygomatic fractures
4. Orbital fractures
C. Fractures of the lower third of the face
(mandibular fractures)

274 /
DESCENDING TRACTS
Lateral corticospinal
Rubrospinal
Pontine _
reticulospinal
Medullary
reticulospinal
Olivospinal
Vestibulospinal Tectospinal
ASCENDING TRACTS
Fasciculus gracilis
Fasciculus cuneatus
Dorsal
spinocerebellar
Ventral
spinocerebellar
Spino-olivary
Spinotectal
Lateral & ventral
spinothalamic
Ventral _
cortlcosplnal
FIG. 19. Cervical spinal cord. Cross section shows the tracts and the relative distribution of fibers.
C = cen/ical; T = thoracic; L — lumbar; S = sacral. (From reference 1 1 , with permission.)
ofquadriparesis, usually worse in the distal upper extrem-
ities, and greater motor than sensory losses.
The final type of cervical spine injury is the accelera-
tion—deceleration, or whiplash, injury. Although it is not
life threatening, this type of injury has achieved great
medicolegal notoriety. A physical basis does, however,
exist—damage has been demonstrated in the anterior
supporting muscles, the longus colli, and also in the lat-
eral and posterior elements (189).
As stated earlier in the chapter, it behooves the physi-
cian to rule out the presence of a cervical spine injury in a
patient with head injury. In a conscious patient, nuchal
pain or tenderness may alert the physician to the pres-
ence of an injury. In a comatose patient, radiological
examination should be routinely performed before mov-
ing the patient. A lateral view, an anteroposterior view,
and an open—mouth view are usually initially adequate.
A swimmer's view may be necessary to visualize C6 to
C7 or C7 to T1 (Fig. 6). If there is any doubt, the neck
should be irrnnobilized in a Philadelphia collar until a
definitive diagnosis can be made with polytomography
or a CT scan. High—resolution CT scanning has been
found to be clearly superior to plain ﬁlms and polyto-
mography in the evaluation of spinal trauma and may
yield even more information in selected cases when
scans are obtained after a myelogram with water—soluble
contrast medium (190,191). If a significant fracture—sub—
luxation is detected and a CT scan rules out the need for
intracranial surgery, cervical traction is applied using
Gardner—Wells tongs or a halo ring without the jacket. If
reduction cannot be achieved with traction, open surgi-
cal reduction may be necessary at a later stage. Many
patients with unstable fractures can be successfully man-
aged with immobilization in a halo jacket for three
months, followed by the use of a Philadelphia collar for
several more weeks (192). However, there is a great deal
of variation in practice in this regard.
A distinction of signiﬁcance in cervical spine injuries
is that between stable and unstable fractures (193). The
incidence of unstable fractures of the cervical spine is
around 25 to 30 percent (194,195). The following frac-
tures may be considered stable: compression or chip
fractures of the vertebral body, unilateral facet or lateral
mass fractures, and fractures ofthe spinous process. Dis-
location or subluxation indicates concomitant ligamen-
tous injury and implies instability. Stable fractures can
be managed with immobilization in a Philadelphia col-
lar. Sometimes instability that is not acutely apparent on
ﬂexion—extension films as a consequence of spljnting of
the spine by paraspinal muscle owing to pain may be-
come apparent on follow—up examination several days
later when the pain has subsided.
Some authors have recommended minimyelography
in the acute phase after spinal injury with neurological
deﬁcits (196). The yield of this procedure is admittedly
low but may be undertaken if other more acutely life-
threatening problems have been dealt with. MRI is pre-
ferred whenever feasible.

Thoracic Spine
The thoracic spine is a relatively rigid and nonmobile
segment of the spine. This is reflected in the low inci-
dence of injuries to this area. However, when injuries do
occur, they indicate that large forces have been applied
and usually result in complete cord transection. Tho-
racic spine injuries are usually flexion injuries. Compres-
sion fractures may occur when axial forces are applied,
as when a person falls on the buttocks. These usually
occur at the thoracolumbar junction. The spinal cord
occupies a greater proportion of the canal in the thoracic
region than it does in the cervical or lumbar area. This
increases the likelihood of neurological injury when
bony damage occurs (197).
In the acute stage in patients with upper thoracic spine
injuries, one must consider the possibility of myocardial
contusion, aortic transecti'on or dissection, or lung inju-
ries. An aortogram may be necessary. It is important,
however, to stress basic immobilization and care during
patient transfer.
Most patients with thoracic spine fractures can be
managed with bed rest followed by an extension brace
for three to four months. However, surgical stabilization
may be preferable because it permits mobilization al-
most immediately. If there is clear—cut neurological dete-
rioration after admission, myelography or MRI should
be undertaken, and surgical intervention is required if
compression is found. Decompressive surgery may incor-
porate either Harrington or Luque rod stabilization or
may use a transthoracic approach (198,199). We have
recently been using pedicular screw fixation with Luque
plates for lower thoracic and lumbar fractures.
Lumbar Spine
Like the cervical spine, the lumbar spine is a mobile
segment and is therefore prone to injury, although less
frequently than the cervical spine. LI and L2 are the
most frequent sites for compression fractures. The conus
medullaris and cauda equina may be involved, resulting
in urinary incontinence and sexual dysfunction in the
male. The principles of management for these in-
juries are similar to those described for the thoracic
spine (200).
Orthopedic Injuries
Fractures can be classified simply as open (com-
pound) or closed. A closed fracture is one in which the
overlying tissues are intact, whereas in an open fracture
the bone is exposed and bacteria can directly enter the
fracture site. The initial treatment of fractures involves
splinting and, in some cases, traction. The agitated pa-
tient should have fractures splinted promptly to prevent
HEAD INJURY / 275
damage to contiguous nerves and major vessels in the
area of the fracture (201). The peripheral pulses distal to
a fracture must be checked periodically to make sure the
vessels are not being impinged upon. Peripheral neuro-
logic function is harder to assess in the comatose patient.
Large volumes of blood may collect in the area of a frac-
ture, and compartment syndromes may develop. These
require measurement of tissue pressures that, if clearly
elevated, call for fasciotomies for decompression. This
occurs more frequently in the upper extremity than in
the lower extremity.
Fat embolism is most frequently seen in patients with
long—bone fracture (202). Its etiology is not fully known.
Because the clinical syndrome is not pathognomonic
and the pathological findings are often scanty, the num-
ber of deaths attributable to this condition is unknown.
Some estimates place the figure as high as 16 percent of
all deaths related to trauma. In the fulminant form, the
previously awake and oriented patient becomes agitated,
rapidly lapses into lethargy and coma, and dies within a
few hours after injury. At autopsy, evidence of massive
fat embolism to the lungs, kidneys, brain, and other or-
gans is found. A definitive diagnosis antemortem is diffi-
cult because of the nonspecific nature of the refractory
shock syndrome. The classic form of fat embolization
appears somewhat later—24 to 72 hours postinjury—
and the symptoms are predominantly cerebral. The syn-
drome may initially present with sudden hypothermia,
followed by agitation, lethargy, stupor, and finally coma.
There is usually tachypnea, cyanosis, and pulmonary
edema as well. The presence of petechiae over the upper
portion of the body, conjunctiva, and in the fundi are
almost pathognomonic clinical signs. The finding of fat
in the urine or blood on microscopic exam is suggestive,
but a negative exam is meaningless. Arterial hypoxemia,
hypocarbia, and thrombocytopenia are common sys-
temic concomitants. Nevertheless, this often remains a
diagnosis of exclusion (203). The mortality rate is high
and is related to the depth and duration of coma. If the
patient does not die, there is usually a complete recovery.
Treatment is mainly supportive, with special attention
paid to ventilation.
Chest Injuries
Chest injuries are frequently encountered in the multi-
ply injured patient, and pulmonary complications fre-
quently affect the morbidity and sometimes the mortal-
ity associated with head trauma (204,205). Simple rib
fractures require no treatment other than analgesics and
possibly local infiltration with anesthetics to reduce pain
in a conscious patient. When several ribs are fractured,
however, a "ﬂail chest" may result. In this condition, the
chest wall is no longer rigid, and paradoxic motion is
seen. This results in a loss of negative intrathoracic pres-

276 / CHAPTER 12
sure during inspiration, reduced ventilation, and possi-
bly atelectasis. It is believed that rather than the para-
doxic movement, the underlying pulmonary contusion
and wet lung may be the major source of respiratory
distress (206). For thisreason, ﬂuid restriction to 1000 to
1200 ml/day, salt—poor albumin, and blood loss replace-
ment with colloids (whole blood, plasmanate) are sug-
gested. If the P02 and PCO2 cannot be maintained within
satisfactory limits with these simple measures, as is the
case in 10 to 20 percent of patients, intubation and con-
tinuous positive—pressure ventilation (PEEP) are recom-
mended. Neurogenic pulmonary edema has been re-
viewed recently (207).
Aspiration pneumonitis is a frequent complication of
severe head injuries and should be avoided as carefully as
possible. It is advisable to place a Salem sump tube into
the stomach soon after intubation (with cuff inflated)
and to empty out the stomach. It is preferable and tech-
nically easier to pass the nasogastric tube prior to endo-
tracheal intubation, but an active gag reﬂex may initiate
a bout of vomiting during attempts to pass the tube; this
results in aspiration, with the physician having no con-
trol over the situation.
The indications for aortography in blunt thoracic
trauma have been reassessed by Gundry and associates,
who concluded that all trauma victims who have a wid-
ened mediastinum should undergo this procedure (208).
On reviewing their results in 173 patients who under-
went aortography to rule out traumatic rupture of the
thoracic aorta, they found mediastinal widening to be
the most reliable indication. According to the re-
searchers, "If you think the mediastinum looks widened,
you should obtain an aortogram." They did not find
other reported signs, such as obscuration of the aortic
knob or loss of sharpness of the aortic outline, to be valid
associations. However, in patients beyond puberty, any
evidence of a high—speed decelerating injury, including
pulmonary contusions and multiple rib fractures (espe-
cially ribs 1 and 2). was considered an adequate reason to
obtain an aortogram.
Cardiac Injuries
Cardiac injuries may be either blunt or penetrating.
The former is usually due to the steering wheel impact-
ing on the anterior chest in an automobile accident. The
electrocardiogram may show ST—T changes, which
usually return to normal over a few days. There may be
an accompanying tachycardia. Although the prognosis
for a patient with cardiac contusion is generally good
(209,210), any surgery should be postponed if possible.
Cardiac isoenzymes may be followed to confirm the
diagnosis, although enzyme fractions may be elevated
secondary to associated injuries.
Penetrating injuries of the heart are often, although
not universally, fatal. Large missile injuries or stab
wounds can result in rapid exsanguination, but small—ca—
liber injuries and even heart rupture from blunt trauma
can be successfully treated (210,211). Again, time is of
the essence. A patient with such an injury rapidly de-
velops signs of cardiac tamponade: distended neck veins,
plethoric appearance, hypotension (systolic pressure
falls more than diastolic pressure, resulting in a
narrowed pulse pressure), paradoxical pulse, muffled
heart sounds, and a widened mediastinum on percussion
and on chest x—ray.
Pericardial tamponade may be diagnosed by aspira-
tion with a 16- or 18—gauge needle inserted just to the left
of the xiphoid process at an angle 45° cephalad and 45°
to the right. Without moving the needle, as much blood
as possible is aspirated. Although this procedure can be
temporarily therapeutic, an open thoracotomy will prob-
ably be necessaiy if there is a significant cardiac defect
(201). Autotransfusion devices may be invaluable in the
management of these cases.
Cardiac Arrest
After trauma, the most common cause of cardiac
arrest is hypoxia and CO2 retention secondary to inade-
quate ventilation. Perhaps of equal importance in the
trauma patient is hypotension caused by hypovolemia
and consequent coronary hypoperfusion. Other causes
include drug overdosage or hypersensitivity, and hyper-
kalemia or cardiac hypothermia owing to the rapid infu-
sion of cold banked blood. It should be stressed that most
of the precipitating causes for cardiac arrest in trauma
patients are preventable. A patient should be quickly in-
tubated and ventilated either at the scene of the accident
or on arrival to the emergency room, and hypovolemia
should be rapidly corrected. Drugs should be used with
care, especially in inebriated patients, who are particu-
larly sensitive to barbiturates and general anesthetics.
Once cardiac arrest has occurred, the team has about
three minutes to restore blood ﬂow to the vital organs. If
the ventilatory and volume status has not been
corrected, this is the first priority.
Pneumothorax
Pneumothorax occurs frequently owing to laceration
of the lungs by fractured ribs, penetrating injuries, or
rupture of the tracheobronchial tree. It often leads to
collapse of the lung and decreased vital capacity. Clinical
signs of a pneumothorax include dyspnea, hyperreso—
nance on percussion, and absence ofbreath sounds over
the lung in question. A large pneumothorax can be de-
tected easily on a chest x—ray, but expiratory films of
good quality may be needed to define a smaller abnor-
mality. Though a patient can tolerate collapse of one

lung fairly well, air can get trapped in the pleural space
by a valve—like mechanism, resulting in a tension pneu-
mothorax. This causes shift of the mediastinum to the
opposite side, thus reducing the ventilatory capacity of
the "normal" lung as well. Unless corrected, this condi-
tion can prove fatal. Although a simple large bore needle
can serve as a temporary release valve, a chest tube must
be inserted as soon as possible.
A chest tube is inserted via a 1.5—cm incision in the
nipple line, where it transects the midaxillary line, using
a scalpel and a finger rather than a trocar. Two heavy silk
sutures are applied in a U—fashion to anchor the tube and
to close the hole later. The chest tube is connected to a
set of drainage bottles or a Pleurevac system, and a con-
tinuous negative pressure of 5 to 20 cm H20 is applied.
Trauma can result in a pure hemothorax, although a
hemopneumothorax is far more common. A hemotho-
rax of less than 300 ml is often not demonstrable on the
upright chest film. A large hemothorax usually presents
with shock secondary to the blood loss rather than respi-
ratory embarrassment. This condition is also corrected
with chest—tube drainage. Thoracotomy may be neces-
sary to overcome major vascular bleeding as from the
internal mammary, intercostals, or pulmonary vessels,
but this is uncommon.
Vascular Injuries
Peripheral vessels are sometimes damaged in the multi-
ple trauma patient, resulting in hemorrhage, arteriove—
nous fistulas, and aneurysms. Control of the hemorrhage
should be achieved immediately using compression.
Tourniquets often result in ischemic injury because they
are left on too long and collateral circulation is blocked
off as well. Ligation or prolonged clamping of the vessel
is also undesirable because it makes reconstruction more
difﬁcult and endangers the survival of the limb.
All injuries in the area of a major blood vessel should
be assumed to involve the vessel, unless proven other-
wise (212). The presence of a distal pulse does not ex-
clude the presence of a vascular injury. Arteriograms
should be performed in such cases, although even these
studies can sometimes be misleading.
Blunt injury to the neck may produce severe extra-
cranial carotid artery spasms or intimal dissection. This
may, in turn, result in a stroke, thus confounding an
already complex picture secondary to the head injury.
Abdominal Injuries
Abdominal injuries, like chest injuries, are either pen-
etrating or blunt. The former are more acutely lethal, but
the latter are more difficult to diagnose and can be the
source of considerable delayed morbidity. Unexplained
shock, in association with abdominal trauma, is due to
HEAD INJURY / 277
abdominal injury unless proven otherwise. Indications
for prompt laparotomy are evidence of peritonitis, unex-
plained shock, gastrointestinal bleeding, and a positive
diagnostic abdominal tap or lavage. An abdominal tap is
first performed (213). If over 20 ml of blood is obtained
or if food particles or feces are evident in the peritoneal
cavity, the tap is considered positive. If not, one liter of
lactated Ringer's or normal saline is infused into the ab-
domen. The patient is then rolled from side to side to
allow good mixing, and the ﬂuid is allowed to flow back
out. When 200 to 300 ml of ﬂuid has been removed, it is
sent for a stat cell count. A count of over 100,000 red
blood cells or 500 white blood cells per cubic mm is
considered positive. Butterworth and associates have
made a strong case for routine peritoneal lavages in pa-
tients with severe head injury "whether or not clinical
signs of shock, abdominal injury, or occult hemorrhage
are present" (38). Peritoneal lavages arc also of value in
detecting hemorrhage in patients with spinal cord inju-
ries, in whom the usual clinical signs may be masked
(214,215). Recent studies indicate that abdominal CT
scanning may be superior to peritoneal lavages in the
evaluation of blunt abdominal trauma (216,217). How-
ever, these studies can take over half an hour to com-
plete, thus limiting their usefulness in patients with intra-
cranial masses or marked instability (217,218).
Renal Injuries
Kidney injuries consist of three main types: (1) renal
contusion; (2) renal laceration, with or without urinary
extravasation; and (3) pedicle injury. Hematuria is the
primary finding in injuries of the urinary tract. It is often
gross but may be microscopic or absent. Abdominal pain
is usually present in the conscious patient. Examination
may reveal evidence of shock, local tenderness, swelling,
and ecchymosis. There is usually marked muscle spasm
in the ﬂank and upper quadrant of the abdomen.
An intravenous pyelogram followed by nephroto—
mography, if necessary, must be obtained whenever kid-
ney injury is suspected. This will not only provide evi-
dence of distortions of the renal or ureteral systems but
also confirm the presence and proper functioning of the
contralateral kidney. CT scan of the abdomen is the test
of choice if the anatomy is not well delineated by these
tests, and aortography may be indicated in select cases.
Most renal injuries (85 percent) are contusions and can
be managed conservatively. The other 15 percent are
major lacerations. Most of these (95 percent) are well
contained and can also be managed nonsurgically. In
about 5 percent of cases, however, surgical intervention
is necessary (219,220). Pedicle injuries also call for ur-
gent exploration. Ureteral injuries are uncommon com-
plications of trauma, being iatrogenic far more often.
Drainage of urine and reconstruction of the ureter is the

278 CHAPTER 12
treatment of choice. Upper urinary tract extravasation is
generally associated with a better outlook than lower uri-
nary tract extravasation because the latter is often asso-
ciated with injuries of the bladder and bowel.
Ophthalrnological Injuries
When an eye injury is noted at the site of the accident,
it is best to cover it with a rigid shield such as a Foxx
shield. Manipulation of the eye, so as to remove a blood
clot or foreign body, should be avoided because a simple
wound can be converted into one with extensively her-
niated ocular contents (22l). Detailed examination can
be deferred until an ophthalmologist sees the patient in
the hospital emergency room.
Patients who have been involved in an automobile
accident often have foreign bodies in their eyes, usually
glass from the windshield or debris from the roadside. In
a conscious patient, such foreign bodies would cause se-
vere discomfort and alert the physician to the problem.
In an unconscious patient, however, they can be over-
looked and lead to further damage. If a foreign body is
suspected, the eye should be thoroughly irrigated with
normal saline using a syringe. If a foreign body is embed-
ded in the cornea or conjunctiva and does not ﬂush out,
mechanical removal may be necessary. This can be ac-
complished with an applicator moistened with saline,
but such a maneuver can result in the loss of consider-
able corneal epithelium. Ideally, the body should be re-
moved with the aid of a slit lamp or corneal microscope
and a fine hypodermic needle. Local antibiotics such as
gentamycin may be prescribed. Because of the danger of
infection, the patient should be seen by an ophthalmolo-
gist each day, and the cornea should be stained with ﬂuo-
rescein until healing has occurred. In any case, ﬂuores-
cein staining should be performed on admission
whenever a superficial eye injury is suspected in order to
rule out a corneal/conjunctival abrasion, which could
become infected if ignored.
The presence of intraocular foreign bodies is usually
not suspected, so they are commonly overlooked. This
possibility must be excluded whenever an eye appears to
have a large or small laceration or penetrating injury. If
even a small foreign body remains in the eye, it may
cause blindness from hemorrhage, infection, or retinal
detachment. The location of a foreign body may be de-
termined using ophthalmoscopy, slit—lainp examination,
dental film, CT scans, ultrasonography, or a combina-
tion of these. Generally, all foreign bodies should be re-
moved, with a few exceptions. The eye may tolerate inert
material such as lead, glass, aluminum, and certain types
of plastic. Organic matter such as wood or plant mate-
rial, however, usually causes an overwl1elrni11gi11ﬂamma—
tory reaction. In any case, systemic antibiotic coverage is
used until danger of infection is passed. Sympathetic
ophthalmia, which is thought to be an autoimmune
uveitis, can result in loss of the uninjured eye, but it is
exceedingly uncommon. Any doubtful eye should be
carefully observed for at least a year, although 80 percent
of cases present in the first three months postinjury.
Once the disease is established, adrenocorticotropic hor-
mone (ACTH) and steroid therapy can be helpful, but
the results are usually dismal.
In certain cases of corneal laceration, atropine or pilo-
carpine may be useful to retract the iris from the wound.
However, these agents should be avoided in patients
with severe head injury, at least in the initial period. This
is especially important when the patient is intubated and
paralyzed and the only means of detecting impending
herniation syndrome is by checking pupillary size and
reactivity. Once a diagnosis has been established and the
patient is in a stable condition with ICP monitoring in
place, these agents may be used. Pupillary dilatation per-
mits a more detailed examination of the fundus and may
also be therapeutic in an inﬂamed eye.
Most often the ocular fundus is normal, even with
severe head injury. Small or large intraretinal hemor-
rhages are sometimes seen, but they are of little conse-
quence to the overall neurological condition. Although
swollen optic discs are occasionally reported to occur
within minutes of raised intracranial pressure, papille-
dema is seen in a minority of patients with serious head
injuries. Moreover, swelling of the optic discs is usually
not seen until the third to fifth day, sometimes after de-
compression of an intracranial mass and relief of ele-
vated intracranial pressure. This delay is curious, be-
cause the papilledema is attributed to axonal dilation as
a result of mechanical impediment to axoplasmic ﬂow.
Severely attenuated retinal aiteries are occasionally due
to very high intraocular pressure from massive swelling
of traumatized orbital tissue. Retinal and optic nerve
infarction follow. This situation is potentially reversible,
if recognized early, by a simple lateral canthotomy.
Various types of traumatic retinopathies have been re-
ported (222). One type is Purtscher's retinopathy, which
consists of multiple scattered hemorrhages in the super-
ﬁcial layers of the retina and deep white areas in the
posterior poles. This injury is associated with sudden ele-
vations in systemic venous pressure, as occurs with crush
injuries or forceful impacts on the chest or abdomen.
SEQUELAE OF HEAD INJURY
CNS injury is a dynamic process. It is generally ac-
cepted that the more severe the impact suffered, the
worse the ultimate outcome is likely to be. Perhaps less
well recognized is the fact that soon after the initial in-
jury, a wide variety of secondary processes come into
play. These sequelae can have a major impact on the
patient's eventual level of recovery. It is not uncommon

to see two patients with similar initial injuries have
widely disparate outcomes, at least partly as a result of
complications. Whereas certain secondary insults occur
in the acute phase, other complications arise or are no-
ticed in the subsequent weeks and months. This section
summarizes the current thinkingaon some of the more
commonly encountered long—term sequelae of head in-
jury.
Cranial Nerve Injuries
Cranial Nerve I
The incidence of olfactory dysfunction after head
trauma has been reported as varying from 2 to 38 per-
cent. Damage to the olfactory system occurs with great
frequency in occipital blows, but the incidence is even
higher after frontal injury. It is the most commonly in-
volved cranial nerve after minor head injury. Impaired
olfactory recognition may result from focal and diffuse
injury to the orbitofrontal and temporal regions. Animal
studies have implicated a role for olfaction in the tem-
poral lobe. Anosmia will occur in almost 50 percent of
patients who sustain rhinorrhea from an anterior fossa
fracture and in about 50 percent of those who require
surgical repair. Spontaneous recovery of functional ol-
faction may occur in more than one—third of patients
over a period of days to five years after injury (223).
Cranial Nerve II
Injury to the visual system occurs in 5 percent of all
patients who sustain head trauma, regardless of severity.
Traumatic loss of vision may occur without overt evi-
dence of injury to the eye. It typically results from an
ipsilateral blow, usually frontal, occasionally temporal,
and rarely occipital. It may occur after minor head in-
jury.
Direct pupillary response to light is the most reliable
early indicator of the extent of optic nerve injury. Oph-
thalmoscopic examination and x—rays are studies of sub-
stantially less value. Unilateral eye injury can be identi-
fied by the presence of decreased to absent pupillary
reactivity to light stimulation, with preservation of the
consensual reaction (Marcus—Gunn pupil). The unin-
volved eye maintains a normal light reﬂex but impaired
consensual response. These reactions indicate an affer-
ent lesion—usually in the optic nerve—in the pupillary
light reflex pathways.
Visual—evoked potentials may provide valuable objec-
tive information even during coma, because patient co-
operation is not essential. This procedure is more accu-
rate than clinical examination in the early diagnosis of
retrobulbar visual dysfunction. CT scans are particularly
valuable in assessing the integrity of the optic canal.
HEAD INJURY 279
As coma resolves, the patient should be evaluated for
light perception. Serial evaluations should be under-
taken for the presence of visual fixation as well as for
localization and tracking of stimuli. The optokinetic re-
sponse may provide evidence of preservation of an
acuity level of 20/200 in at least part of the visual field.
The term "cortical blindness" should be reserved for
patients who demonstrate amaurosis with reactive pu-
pils, not for individuals who have incurred paitial visual
field loss. Most patients with cortical blindness will re-
gain some limited visual capability via secondary visual
pathway systems. The patient's response to high—inten—
sity moving stimuli should be evaluated. The patient
who is cortically blind with denial of the visual loss (An-
ton's syndrome) has usually suffered bilateral occipital
lobe infarctions secondary to posterior cerebral artery
compression at the tentorial edge caused by herniation.
Cranial Nerves HI, IV, and VI
Extraocular muscle dysfunction causes diplopia and
may result from central or peripheral motor dysfunc-
tion. Diplopia may contribute to the confusion of the
patient arousing from coma. Eye patching can abolish
the double image, but when the patient has the ability to
suppress the second image, eye patching should be dis-
continued. The common practice of alternating the
patch between the affected and the unaffected eye is
meant to prevent amblyopia. However, because amblyo—
pia does not occur in the adult population, it is reason-
able to patch the sound eye to stimulate maximal motor
activity of the affected eye.
Abnormal head postures may be utilized to compen-
sate for paretic extraocular motor function. This com-
monly occurs in cranial nerve IV paresis. The fourth
cranial nerve is not only a depressor but also an intorter
of the eye; the patient tends to compensate by tilting the
head. Attempts at normalizing the head position may
prevent the patient from achieving binocular vision.
Head tilt may also result from nystagmus, because stabi-
lizing the head against the shoulder may dampen the
nystagmus. Visual field deficits also frequently produce
head turning in order to align the remaining visual field
properly.
Spontaneous resolution of paresis of eye movements
occurs with considerable frequency. In cranial nerve IH
paresis, a residual superior rectus weakness may remain,
and the patient may complain of occasional diplopia.
Cranial nerve IV lesions spontaneously resolve in 65 per-
cent of unilateral involvement and in 25 percent of the
bilateral cases (224). Though some have argued that sur-
gical correction in permanent paralysis may be merely
cosmetic, Fells and Waddell have demonstrated that res-
toration of binocularity can occur in the majority of
cases (225).

280 / CHAPTER 12
Cranial Nerve V
Injury of the trigeminal nerve is relatively uncommon.
The patient who demonstrates an insensitive cornea, as
indicated by an absent corneal reﬂex, in the presence of
facial nerve paresis (especially if the lacrimal branch is
involved) is at great risk to develop repeated neurotro—
phic corneal ulceration and possible loss of vision. These
patients should be considered early for protective tar-
sorrhaphy. Protective lubricants should be used liberally
as part of routine nursing. Tear production, regulated by
the lacrimal branch of the facial nerve, may be evaluated
by the Schirmer tear test.
Cranial Nerve VII
The status of the facial nerve must be documented at
the initial examination. If paralysis is of immediate on-
set, and CT demonstrates compromise of the facial
canal, prompt exploration for nerve decompression may
be undertaken. The facial nerve traverses a longer bony
canal than does any other cranial nerve and is therefore
extremely vulnerable to injury. Ten to 30 percent of lon-
gitudinal fractures of the temporal bone and 30 to 50
percent of transverse fractures result in facial nerve
palsy.
If there is delayed development of paralysis, the prog-
nosis is substantially better if the paralysis is not bilat-
eral, and the patient should be followed with serial facial
nerve testing. Neurophysiologic testing including nerve
conduction and electromyographic studies should dem-
onstrate some signs of recovery within eight weeks, if
recovery is to occur. In such cases exploration is proba-
bly not necessary, because complete recovery occurs in
75 percent of the cases and partial recovery in 15 per-
cent
Cranial Nerve VIII
The inner ear is the most commonly damaged sensory
organ after severe head injury. Vertigo may occur as a
result of vestibular apparatus damage or labyrinthine
concussion. Hearing loss is primarily conductive as a re-
sult of ossicular chain disruption or blood in the middle
ear. The ossicular chain is most often disrupted at the
incudostapedial joint. Surgical intervention and pros-
thetic replacement of the dislocated component are es-
sential for restoration of hearing.
Transverse fractures of the petrous portion of the tem-
poral bone usually produce sensorineural hearing loss.
The labyrinthine capsule is generally disrupted, resulting
in severe vestibular and cochlear damage, including
functional destruction of the semicircular canals, utricle,
and saccule. Because the fracture line in transverse frac-
tures is perpendicular to the facial nerve, both nerves are
damaged in 50 percent of patients with this fracture.
Assessment of oculovestibular responses may provide
early information regarding the status of the system, and
later electronystagmography may confirm end—organ
impairment of the vestibular nerve. No reliable diagnos-
tic test of central vestibular nerve function is available.
Brainstem auditory—evoked potentials can contribute sig-
nificantly to the evaluation of the integrity of auditory
nerve and cochlear nucleus, but they provide little in-
sight into the structure or function of the vestibular
nerve component.
Locked-in Syndrome
The terms "locked—in syndrome" and "akinetic mut-
ism" are used synonymously. Damage to the corticobul—
bar and corticospinal pathways in the ventral pons re-
sults in a de—efferented state characterized by tetraplegia
and mutism. The patient remains aware and responsive,
and higher cortical function remains unaffected.
Supranuclear ocular pathways are spared so that eye
movement control is at least partially preserved, usually
in the vertical and sometimes in the horizontal plane.
Nonoral communication is therefore possible, either uti-
lizing eye movements or blinking, and the use of appro-
priate interface systems can provide sufficient communi-
cation with which to demonstrate retained cognitive
abilities. The syndrome results most often from vascular
infarction and, therefore, is not commonly found as a
result of trauma. Locked—in syndrome must be clearly
differentiated from the vegetative state in which sen-
tience is not preserved, despite a return of sleep—wake
cycles and a deceptive appearance of neurologic recov-
ery ("coma vigil") that frequently gives the patient's fam-
ily and friends an unjustified sense of optimism.
Peripheral Neuropathies
Polyneuropathies are reported as an early complica-
tion of sepsis and other critical illnesses in up to 50 per-
cent of patients in intensive care units (226). This com-
plication is occasionally recognized clinically in
head—injured patients. The neuropathy usually subsides
as the critical illness comes under control. Neuropathies
associated with fractures can occur at the fracture site.
However, compression neuropathies can result from im-
mobility and localized pressure to a nerve over a bony
prominence. Such compression most commonly affects
the ulnar and peroneal nerves. Whenever a limb remains
ﬂaccid, the possibility of neuropathy exists. In the uncon-
scious patient, physical evaluation can be quite limited,
and nerve—conduction studies may be valuable.
Plexopathies involve many muscle groups, so that
tone is diminished from what would be expected. Direct
injury to the shoulder or the pelvis may result in stretch-
ing, contusion, compression, or laceration injuries to the
brachial or lumbosacral plexuses. The pattern of ﬂacci-

dity in an extremity should alert one to reevaluate the
force mechanisms of the initial injury and to consider
appropriate electrophysiologic studies. If bone fracture
has occurred, excessive callift development may result in
adjacent nerve compression, with late development of
nerve injury.
Posttraumatic Hydrocephalus
Deﬁnition
The syndrome of posttraumatic hydrocephalus (PTH)
must be denned using both radiologic and neurologic
criteria, because both features must be present to make
the diagnosis. In simple terms, PTH may be described as
ventricular dilation without sulcal enlargement, asso-
ciated with a clinical syndrome that may vary from deep
coma to the typical picture of normal—pressure hydro-
cephalus: dementia, ataxia, and urinary incontinence
(see also Chapter 9, "Hydrocephalus").
Incidence
Although ventricular dilatation is a common finding
after head injury, particularly when the injury is severe,
true PTH is relatively uncommon. The incidence of
posttraumatic ventricular dilatation has been variously
reported to be between 29 and 72 percent (227). Obvi-
ously, differences in diagnostic methods, definition of
ventricular enlargement, and patient characteristics
must account for these wide differences. Kishore and
coworkers defrned significant ventriculomegaly as a dis-
tended appearance of the anterior horn of lateral ventri-
cles, enlargement of the temporal horns and third ventri-
cle, and normal or absent sulci (228). They then
prospectively followed 100 consecutive severely head—in—
jured patients with serial CT scans of the head for over a
year. Twenty—nine patients developed ventriculomegaly
within the year, and 27 of the 29 developed it within the
first two weeks.
Cardoso and Galbraith reported a retrospective review
of possibly a more heterogenous group of 2374 patients
with severe head injury (229). Of this group of patients
(who were not scanned or followed according to a prede-
termined protocol), l7 (0.7 percent) developed symp-
tomatic hydrocephalus. Of these, eight patients (47 per-
cent) improved markedly, and four (24 percent) slightly,
after shunting.
In a CT study performed at least three months after
head injury, Gardeur and associates found ventricular
enlargement in 78 percent of the patients (230). Simi-
larly, van Dongen and Braakman reported CT evidence
of cerebral atrophy in 86 percent of patients examined
one to four years after closed head injury resulting in
coma for at least six hours (231). Levin and coworkers
studied the area of the lateral ventricles on CT scans
HEAD INJURY / 281
obtained at least 30 days after severe closed head injury
in 32 young adults and reported enlargement in 72 per-
cent of the cases (232).
Posttraumatic hydrocephalus must be distinguished
from posttraumatic cerebral atrophy. The former term
denotes an active, treatable condition, which com-
pounds existing neurologic deficits, whereas the latter
represents brain parenchymal resorption secondary to
diffuse tissue injury. Unfortunately, this distinction is
not always readily apparent. CT scanning has certainly
made the diagnosis easier to make, and. interestingly,
there has been a drop in the reported incidence of PTH
to between 1 and 8 percent, as compared with 21 to 36
percent in the pneumoencephalogram era (233,234).
Pathophysiology
It is generally believed that P'IH results from an im-
pairment in the ﬂow and absorption of CSF. Although
radiologic and pathologic evidence suggests that this
blockage is usually around the cerebral convexities, it is
certainly possible that blockage of the arachnoid granu-
lations by subaraclmoid blood may play a role (235). In
any case, subarachnoid hemorrhage seems to be a fea-
ture common to these two hypotheses.
Clinical Features
PTH may be manifested in a variety of ways. As re-
ported by Kishore and colleagues. 27 of the 29 patients
in their series developed the syndrome within two weeks
of injury (228). There is a reported case of ventricular
enlargement within seven hours of a head injury, result-
ing in a rapidly deteriorating level of consciousness and
early herniation. However, more delayed presentations
are certainly possible. In fact, remote trauma is rather
commonly reported in series of patients with normal-
pressure hydrocephalus (NPH).
PTH may present as classic NPH, with dementia,
ataxia, and urinary incontinence. However, altered lev-
els of consciousness and even coma may occur as part of
the syndrome. Because severe head injury often results
in fairly extensive neurologic dysfunction, these features
may be hard to separate from the effects of brain trauma
in the acute phase. Intracranial pressure monitoring and
serial CT scans can be useful in this setting. In the more
chronic phase of recovery, a deteriorating level of con-
sciousness, decreasing functional capacity, or any of the
features of NPH should serve as a tip—off. Some atypical
manifestations, such as emotional problems, bilateral
extensor responses, seizures, and leg spasticity, have also
been reported.
Radiologic Features
Kishore and coworkers have used the following CT
criteria to define hydrocephalus: (1) distended appear-

282 / CHAPTER 12
ance of the frontal horns of the lateral ventricles; (2) en-
largement of the temporal horns and the third ventricle;
(3) normal or absent sulci; and (4), if present, enlarge-
ment of the basal cisterns and fourth ventricle. Periven—
tricular lucency was used as an indicator ofcon1municat—
ing hydrocephalus. Ex vacuo ventriculomegaly, or
atrophy, is characterized by diffuse ventricular enlarge-
ment with prominent sulci and no periventricular lu-
cency. Levin and colleagues used ventricular area as cal-
culated from a CT scan to study the relationship between
ventriculomegaly and neuropsychologic deficits after
closed head injury (232). Although this technique is
clearly the most accurate way of assessing ventricular
size, there is no radiologic method that can reliably pre-
dict outcome following shunting.
Periventricular edema has been recognized as a patho-
logic and radiologic feature of hydrocephalus. Normally,
ﬂuid from the brain parenchyma moves across the epen—
dymal lining into the ventricles. In the presence ofhydro-
cephalus, this normal direction of ﬂow is reversed, and
ﬂuid moves from the ventricles into the periventricular
white matter. Since T2—weighted MRI images are very
sensitive for water, it was hoped that this technique
would define the population with symptomatic hydro-
cephalus. Unfortunately, this is not quite so simple.
Zimmerman and associates reported that a review of 365
consecutive MRI studies revealed some degree of peri-
ventricular hyperintensity (PVH) in 93.5 percent of
cases, regardless of diagnosis (236). Of the six patients in
their series with NPH, two had mild nonspecific PVH
and four had prominent PVH, but in all cases multiple
white matter hyperintense foci (presumably representing
infarctions) were also present. The degree of PVH was
similar to that seen in nonhydrocephalic elderly pa-
tients and could therefore not be used as a criterion for
shunting.
Selection 0fPatients for Shiinting
There is no single clinical, radiologic, or physiologic
feature that can serve as an accurate and infallible crite-
rion for shunt placement. Needless to say, if there is se-
vere underlying brain damage, shunting, even if it is in-
dicated, may not improve functional outcome
significantly. Nevertheless, every patient should be care-
fully evaluated and given the benefit of the doubt, be-
cause shunting can make a difference in a substantial
number of cases. Approximately 50 percent of patients
with ventriculomegaly will improve significantly after
shunting. If a patient meets the clinical and radiologic
criteria deﬁned earlier, every effort must be made to ob-
tain an assessment of the craniospinal axis pressure. If
the patient has an ICP monitor in place, this information
is readily available. If not, a lumbar puncture can be
performed with the patient lying ﬂat on his or her side,
and the ICP recorded when he or she is relaxed and the
abdomen is not being compressed. No firm pressure
guidelines are available in PTH for shunting. It stands to
reason that if the lumbar CSF pressure is lower than 136
mm H20 (10 mm Hg), a shunt is unlikely to help, but if
it is higher than 276 mm H20 (20 mm Hg), it may be
very useful. However, when the pressures are in between,
this single reading does not provide a clear answer.
Draining 20 to 30 ml of CSF may sometimes result in
significant, albeit transient, clinical improvement, thus
tipping the balance in favor of shunting.
When the lumbar pressure is normal, shunting may be
considered if a classic picture of NPH exists. Salmon
found that five of nine posttraumatic patients with this
syndrome improved after shunting regardless of other
test results (237). If the picture is not clear, a brief period
(12 to 48 hours) of ICP monitoring may be helpful. In
one study of 12 subjects, patients who showed variable
ICP improved following shunt surgery, but those with
consistently flat ICP tracings did not (238). Brgesen,
Gjerris, and Srensen, however, reported that ICP data
per se did not help them in a series of patients with
"true" NPH who had mean ICPs not exceeding 12 mm
Hg (239). In this series, they reported that conductance
to CSF outﬂow was a much more relevant measurement,
but this method has not become widely used in clinical
practice.
Cisternography has been extensively used in the past
in the evaluation of patients with NPH. When a radionu-
cleotide is injected into the lumbar subarachnoid space,
it normally ﬂows over the cerebral convexities and is
absorbed into the major venous sinuses via the arach-
noidal granulations. When the normal ﬂow of CSF over
the convexities is impeded, the isotope backs into the
ventricles within an hour of the injection and lingers
there for 24 to 72 hours. Although this ventricular reﬂux
was thought to be typical of NPH, its correlation with
improvement after shunting has been only fair. Cister-
nography plus an assessment of the clinical picture, com-
bined with lumbar or intracranial pressure monitoring
and neuropsychological testing, form the basis for selec-
tion for shunting.
Cerebrospinal Fluid Fistulas
Deﬁnition
A traumatic cerebrospinal ﬂuid fistula may be defined
as a CSF leak occurring as a consequence of a head in-
jury. Fistulas may present as rhinorrhea, otorrhea, or
pneumocephalus.
Incidence
CSF ﬁstulas reportedly occur in 0.25 to 3.0 percent of
all patients with a head injury and in 5 to 11 percent of

those with a basal skull fracture (240-242). An estimated
150,000 cases of traumatic rhinorrhea occur in the
United States each year (243). In one series, CSF oto-
rrhea occurred in 7 percent of 300 basal skull fractures
(244). In this same series, pneumocephalus occurred in
about one—third of patients with rhinorrhea, although
this may be an isolated finding (244).
CSF Rhinorrheci
This condition occurs in about 25 percent of patients
with an anterior basal fracture. CSF may leak via the
frontal sinus (through the cribriform plate or orbital
plate of the frontal bone), via the sphenoid sinus, and.
less frequently, via the clivus. On occasion, with a frac-
ture of the petrous part of the temporal bone. CSF may
enter the eustachian tube and, if the tympanic mem-
brane is intact, drain from the nose. Drainage begins
within 48 hours of injury in almost 80 percent of cases
(245,246). The ﬂuid is watery and nonmucoid, and it
contains glucose. A glucose concentration of 30 mg/ 100
ml or greater is very suggestive of CSF. Dextrostix and
similar products are unreliable because normal nasal se-
cretions may give a positive reaction, but protein electro-
phoresis combined with immunofixation for an isoform
of transferrin has recently been shown to be useful in
identifying CSF (247).
Several aspects of the management of CSF rhinorrhea
remain controversial, including the use of prophylactic
antibiotics, the timing of surgery, and the role of lumbar
drains. In general, 80 percent of fistulas will stop leaking
within one week (248). The patient should be nursed in a
position that stops or minimizes the leak. If the leak has
not stopped in about three days, a lumbar subarachnoid
drain should be inserted and allowed to drain at about
shoulder level for three to seven days. If the leak persists
at 10 to 14 days, surgery should be considered, and diag-
nostic testing should be initiated to identify the site of the
leak. lohexol (Omnipaque) CT cisternography is
currently considered to be the diagnostic test of choice
(249). In an intermittent CSF leak, however, this test
may give a false negative result. Various maneuvers,
such as the Trendelenberg position, Valsalva's maneu-
ver, and lumbar subaraclmoid saline injection, have
been described to maximize the probability of detecting
the site of leakage (250).
Once the fistula site has been identified, it can be sur-
gically repaired using an intracranial (intradural or ex-
tradural) or a transsphenoidal approach, depending on
the site of the leak. Sense of smell may be lost as a result
of the initial injury, especially with fractures of the eth-
moidal bone. The incidence of anosmia may be as high
as 80 percent. An intracranial frontal fossa ﬂoor repair is
associated with a high incidence of anosmia, even when
smell is normal preoperatively. The extradural repair
HEAD INJURY / 283
technique may be advantageous in this regard (251). The
size of the defect may be rather small, and the surgeon
may face some difficulty in finding the dural tear. Lyoph—
ilized dura, pericranium, or fascia lata is often used to
patch the defect. We have used human fibrin adhesive to
provide an additional seal.
CSF Otorrheci
This condition occurs when the petrous bone is frac-
tured, the overlying dura mater and arachnoid are torn,
and the tympanic membrane is perforated. Fractures of
the petrous bone are classified as longitudinal or trans-
verse, based on their relationship to the long axis of the
petrous pyramid; however, most fractures are mixed. Pa-
tients with a longitudinal fracture present with conduc-
tive hearing loss, otorrhea, and bleeding from the exter-
nal ear. Patients with a transverse fracture generally have
a normal tympanic membrane and demonstrate sensori—
neural hearing loss from damage to the labyrinth, coch-
lea, or the eighth nerve within the auditory canal. Facial
paresis is present in up to 50 percent of patients (252).
Longitudinal fractures are four to six times more fre-
quent than transverse fractures, but they are much less
likely to cause facial nerve injury—.
CSF otorrhea ceases spontaneously in the overwhelm-
ing majority of patients within a week. The incidence of
meningitis in patients with otorrhea is probably about 4
percent, as compared with 17 percent with CSF rhinor-
rhea. In the rare event that it does not cease, lumbar
drainage and even surgery may be undertaken.
Prophylactic Antibiotics
The role of prophylactic antibiotics in the manage-
ment of CSF otorrhea or rhinorrhea remains uncertain
because of a paucity of data, and their use is therefore
varied in different centers. The only prospective random-
ized study of the use of penicillin in patients with rhin-
orrhea or otorrhea was limited to 52 patients (253). Men-
ingitis developed in only one patient in study, and this
occurred in a placebo—treated patient who had an intra-
ventricular foreign body. The authors concluded that
their study did not support the routine use of prophylac-
tic antibiotics in these cases.
Posttraumatic Vascular Complications
Deﬁnition
Posttraumatic vascular complications can involve
both the arterial and the venous systems and may occur
either extracranially or intracranially. They are usually
noted at the time of initial impact, or soon after the in-

284 CHAPTER 12
jurv is sustained, but occasionally may not become ap-
parent until several days or even months after the injury.
Incidence
The true incidence of vascular complications asso-
ciated with head injury is unknown because of the lim-
ited number of epidemiologic studies. Furthermore,
with cerebral angiography having been virtually elimi-
nated from the routine evaluation of head—injured pa-
tients since the advent of CT, this database is not likely to
be improved upon. It is important, therefore, that clini-
cians maintain a high index of suspicion and obtain an-
giograms when the clinical picture cannot be explained
by the CT or MRI scans. One study of 2000 head—injured
civilians reported a 4.2—percent incidence of vascular in-
juries (254).
Classification
Posttraumatic vascular complications may be classi-
ﬁed as follows:
A. Arterial
1. Ceryical
a. Direct carotid or vertebral artery transection
b. Thromboembolic occlusion from a traumatic
nidus or irrtimal dissection
c. Traumatic arterial aneurysms
d. Traumatic arteriovenous fistulas
2. Intracranial
a. Thromboembolic occlusion
b. Traumatic aneurysms
c. Traumatic arteriovenous fistulas
d. Carotid—cavernous fistulas
B. Venous
1. Dural venous sinus thrombosis
C. Traumatic vasospasm
Discussion
The interested reader is referred to an excellent review
by Kassell, Boarirri, and Adams (255). Penetrating i1rju—
ries of the neck obviously call for angiography and surgi-
cal exploration if the platysma has been penetrated. Arte-
rial occlusion secondary to blunt neck trauma occurs
infrequently, with an estimated incidence of 0.5 percent.
The injury— is said to occur most commonly at the C2
leveL with both the carotid and vertebral arteries. Clini-
cal diagnosis is often difﬁcult, and there may be a symp-
tom—free period, usually of less than 24 hours. The pa-
tient may experience transient ischemic attacks, form a
neck hematoma, or develop Horner's syndrome. Once
occlusion occurs, a focal rreurologic deficit may become
apparent. In cases of severe head injury, this may be hard
to separate from the effects of the primary brain injury.
The mortality rate for traumatic carotid thrombosis in
the neck is reportedly between 40 and 90 percent. Verte-
bral artery occlusions are less frequently documented
and have a lower associated mortality: 19 percent when
one vertebral artery is occluded and 46 percent when
both are occluded. Anticoagulation medications may be
given in selected patients in whom the head injury is
mild and the risk of intracranial hemorrhage is low; how-
ever, the value of anticoagulation treatment in these pa-
tients has not been established.
Posttraumatic irrtracrarrial aneurysms are very u1r—
common. A study by El Girrdi and associates reported
only seven cases among 2000 head—injured patients
(254). Furthermore, there were only two such aneurysms
in more than 3000 penetrating head wounds reported
from the Korean and Vietnam wars. Unlike congenital
"berry" aneurysms, posttraumatic aneurysms are more
likely to occur near the cortical surface than at major
arterial bifurcations. There is often no neck for clipping,
but surgical exposure and clipping or wrapping remains
the treatment of choice.
Irrtracrarrial traumatic arteriovenous fistulas are also
uncommon. They occur most often between the middle
meningeal artery and a meningeal vein. They are usually
associated with a penetrating head injury or a depressed
skull fracture. The risk of hemorrhage from these lesions
is uncertain. They can be treated by embolizatiorr via the
external carotid artery or by direct surgical excision.
Carotid—cavernous (CC) fistulas are the best recog-
nized of all posttraumatic vascular injuries. Although rel-
atively uncommon, their characteristic features make
them a well—recog1rized clinical entity. Sixty to 80 per-
cent of CC ﬁstulas are traumatic in origin; the rest pre-
sumably arise spontaneously. Spontaneous CC fistulas
occur more commonly in older women, whereas those
from trauma are found more commonly in young men.
The clinical features can include proptosis, chemosis,
bruit, ophthalmoplegia, visual deterioration, and head-
ache. A bruit may be palpable, arrd a murmur can be
heard with a conventional or Doppler stethoscope. Arte-
riography is the diagnostic procedure of choice. The natu-
ral history of CC ﬁstulas warrants intervention: spo1rtane—
ous closure is uncommon, and the usual course is one of
progressive visual loss (40 to 50 percent will develop
blindness), intolerable bruit, or disfiguring proptosis (see
also Chapter 4, "Aneurysms and Carotid—Cavernous Fis-
tufas"). Although various approaches have been used for
their treatment, the current treatment of choice is occlu-
sion of the fistula with a detachable balloon, with preser-
vation of blood ﬂow in the carotid artery (256). When
this is not technically possible, various alternative ap-
proaches may be used, including balloon occlusion of
the internal carotid artery, packing of the posterior cav-
ernous sinus with thrombogenic material or wire, and
occlusion of the sinus by packing via the ophthahnic
vern.

PROGNOSIS
The Glasgow Outcome Scale (GOS) has been widely
accepted as a standard means of describing outcome
in head injury patients. This is a simple five—point
scale (257):
Patient returns to preinjury
level of function
Moderately disabled Patient has neurological
[MD] deficits but is able to look
after self
Severely disabled Patient is unable to look after
[SD] self
Vegetative [V] No evidence of higher mental
function
Good recovery [G]
Dead [D]
These categories can be lumped together as either good
outcome (G, MD) or poor outcome (SD, V, or D). Based
on logistic regression, a method has been described for
assigning patients into one of these two categories. This
method has been described in detail elsewhere (258). A
simpler method is based on discriminate analysis and
can assign patients into one of four outcome categories
(G, MD, SD, or V/D) (259). Only age, pupillary re-
sponse, and motor score are required for this. (Fig. 20).
This model was based on data collected from 523 pa-
tients with a severe head injury. If a prediction fell into
the correct outcome group, this was termed speciﬁcally
accurate. If an outcome group adjacent to the actual out-
come was accepted, the prediction was described as
grossly accurate. With this model, the overall specific
prediction rate was 78 percent and the grossly accurate
prediction rate was 90.4 percent. It should be pointed
out that the polar predictions—good recovery and death
—are much easier to predict accurately than the inter-
mediate categories of moderately or severely disabled. It
should also be noted that these prediction models are
based on neurological function alone, whereas mortality
can often result from unexpected medical complica-
tions. The value of such predictions lies in the clinician's
ability to counsel the patient's family and possibly to
compare the effect of newer therapies on smaller groups
of patients, with statistically predicted outcomes based
on past experience.
Unfortunately, the resources available for medical
treatment are often finite, and difficult decisions some-
times must be made regarding the optimal allocation of
efforts. A recent analysis by Gibson and Stephenson
showed that mortality after severe head injury could be
predicted with 100 percent accuracy in about 15 percent
of patients who reached their intensive care unit (260).
This simple bedside scale may be useful in identifying
that subgroup of patients in whom a fatal outcome is
virtually assured regardless of maximal therapeutic ag-
gfessiveness.
HEAD INJURY / 285
BILATERALLY NORMAL PUPILLARY RESPONSE
Motor Score
UNILATERALLY ABSENT PUPILLARY RESPONSE
BILATERALLY ABSENT PUPILLARY RESPONSE
FIG. 20. Predicting outcome in severe head injury. Outcome
can be predicted at admission with a reasonable degree of
accuracy based on three clinical indicators: pupillary re-
sponse, age, and motor response. (From reference 259, with
permission.)
CONCLUSION
Head injury is a common and potentially devastating
disorder with vast socioeconomic implications. The out-
come from head injury is inﬂuenced by various factors,
including the severity of the initial impact, associated
injuries suffered, and the occurrence of secondary com-
plications—both systemic and cerebral.
Major advances have been made over the past two
decades in the classification of this disease and explora-
tion of its pathophysiology. Significant reduction in mor-
tality and morbidity associated with severe head injury
has been achieved with aggressive management proto-

286 / CHAPTER 12
cols that emphasize early ventilatory control, minimal
delay to surgical evacuation of mass lesions, careful con-
trol of intracranial pressure, maintenance of adequate
cerebral perfusion, and optimization of the intracranial
milieu. The anatomic basis of mild and moderate head
injury is beginning to be better understood. Current ef-
forts in the field are being directed at the development
and clinical testing of new drugs and physiological inter-
ventions. It is anticipated that further improvements in
the field will be derived from the cumulative benefit of
several such interventions. Historically, advances made
in the field of neurotrauma have generally had a favor-
able impact on a variety of other neurological disorders.
ACKNOWLEDGMENTS
The author wishes to express his sincere gratitude to
Stephanie Goldfield for preparing this manuscript, Me-
linda Mosheim for organizing and preparing the photo-
graphs, Sangita Rangala for researching the references,
I an Redden for the excellent illustrations, and Dr. Win-
ifred Hamilton for helping to pull it all together. Parts of
this chapter are derived from chapters I wrote for D. P.
Becker and S. K. Gudeman (262) and M. Rosenthal
(263) and are used with the permission of the publishers.
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1969;56:23-31.

CHAPTER 13
Pain
John D. Loeser
Concepts, 293
AblativePr0cedures,295
Peripheral Neurectoiny, 295
Syrnpathectorny, 296
Spinal Dorsal Rhizotorny, 296
A11terolateral Spinal Tractotorny, 297
Corninissural Myelotorny, 298
Facet Rhizolysis, 298
Cranial Neurectoiny, 298
CONCEPTS
The clinician's approach to the inanageinent of the pa-
tient with pain is a function of the model used to explain
the patient's signs and symptoms. Most patients and
their physicians adhere to the Cartesian model for pain,
which argues that a noxious stimulus is responsible for
the patient's complaint. The error of this viewpoint
should be obvious to every neurologist and 11eurosur—
geon; yet, inappropriate prescriptions for medications
and rest and excessive numbers of operations are ample
testimony to the failure to understand the inechanisins
underlying the patient's complaints of pain. Since pa-
tient selection is the rnost important factor in the surgical
inanageinent of pain, a valid scheme for analyzing the
relevant factors contributing to the patient's complaints
is the first step toward successful therapy (1).
Physicians must recognize that the only measures of
the success or failure of a treatment for pain are the pa-
tient's pain behaviors—those things the patient says or
does that can be used to i11fer events within the patient's
body. Pain behaviors are quantifiable and they are all
real. One should never challenge the validity of the pa-
tient's pain behaviors; instead, one should ask: "What
are the factors that lead this patient to rna11ifest pain
behaviors?"
J. D. Loeser: Department of Neurological Surgery, Univer-
sity ofWashington, Seattle, Washington 98195.
293
Princi les 0fNeur0surgery,
edite by Robert G. Grossman. Rosenberg © 1991.
Published by Raven Press, Ltd., New York.
Gangliolysis, 299
Cranial Rhizotorny, 299
Microvascular Decornpression of the
Trigerninal Nerve, 299
Medullary Trigerninal Tractotoiny, 300
Thalainotoiny, 300
Cinguluinotoiny. 301
Hypophysectorny, 301
Electrical Stirnulation, 301
References, 302
It is helpful to recognize four phenomena that can lead
to the complaint of pain and other behaviors suggesting
tissue damage (Fig. 1). Nociception is the activation of
specialized nerve endings and their axons in the tissues
designed to co11vey to the spinal cord and brain that tis-
sue darnage is about to or has occurred. Nociceptive in-
formation is carried exclusively by A delta and C fibers,
but not all of these finely rnyelinated or unrnyelinated
axons are utilized for nociception. Nociceptive axons ap-
pear to be targeted on specific neurons in the dorsal
horn, but it is clear that there is no nociceptive specificity
to spinal cord or higher systeins. Nociception can exist
without pain, as seen with spinal anesthesia, after spinal
cord injury or during hypnosis. Most experiinental stud-
ies of pain relate only to nociception. Nociception is the
preponderant factor in acute pain, but it often plays little
or no role in chronic pain due to benign diseases.
The response of the nervous system to a nociceptive
event can be labeled pain. In an intact anirnal, 11ocicep—
tion is the usual cause of pain. I11juries to the peripheral
or ce11tral nervous system can, in some patients, lead to
the complaint of pain in the absence of tissue damage
(and the ensuing nociception) where it hurts. These are
known as ce11tral pain states or deafferentation pains (Ta-
ble 1). With the exception of tie douloureux, all of these
pains are notoriously difficult to alleviate. It is critically
important to recognize those pains that exist without no-
ciception; treatment strategies, both pharinacologic and
surgical, must be different. Both the peripheral events

294 / CHAPTER 13
FIG. 1. Components of pain.
and the central pathways of pain resulting from injury to
the nervous system are different from those pains that
are due to tissue damage.
Pain, which is a sensation, is one of the many causes of
suﬁering, defined here as a negative affective response to
pain, or to depression, isolation, fear, or anxiety. Cassell
has insightfully de11ned suffering as a perceived threat to
the physical or psychological integrity of the individual
(2). Suffering is a ubiquitous condition in the i11dustrial—
ized world; pain is only one of its many causes. Yet, we
(patients and doctors) use the vocabulary of pain when
we mean suffering. An annoying person is called "a pain
in the neck." A book entitled Worlds of Pain is about life
in the Chicago stockyards at the turn of the century. Suf-
fering is frequently associated with depression; narcotics,
muscle relaxants, and sedative—hypnotics are all causes
of depression and often increase suffering.
Pain behavior is the result of suffering; it is best de-
nned as the things a person says or does that are usually
interpreted as indicating the presence of nociception.
Pain behaviors include moaning, grimacing, lying down,
taking medications, refusing to work, and talking about
pain. Like all other forms ofbehavior, pain behaviors are
strongly influenced by environmental responses: they
can be learned. Learning is not under conscious control;
it just happens, especially when the behavior is present
over a period of time. Pain behavior will be subject to
environmental consequences, regardless of the factors
that initially led to the pain behavior. Observations
TABLE 1. Deafferentation pain states
Postparaplegic pain
Postthoracotomy pain
Postherpetic neuralgia
Tic douloureux
Atypical facial pain (some)
Brachial plexus avulsion pain
Arachnoiditis
Phantom limb pain
Stump pain
Thalamic pain
Peripheral neuropathy pain
Tabes dorsalis
Lumbosacral plexus avulsion pain
made repeatedly in comprehensive pain management
clinics indicate that environmental factors are often the
cause of chronic pain; nociception may have been the
inciting event, but the body has long since healed the
original injury.
The neurologist or neurosurgeon infrequently deals
with acute pain (which almost always results from 11oci—
ception). Most referrals involve chronic pain, either
from injury to the nervous system (pain without 11oci—
ception) or from affective or environmental factors (suf-
fering or pain behavior). The potential roles of tissue
damage, pain without tissue damage, affective distur-
bance, and environmental reinforcers must be consid-
ered in the assessment of the patient manifesting pain
behaviors. It is important to recognize that chronic pain
resulting from cancer is almost always due to continuous
nociception and/or to injury to nerves. Like acute pain,
this type of chronic pain must be treated aggressively to
relieve the patients suffering and thereby reduce pain
behaviors. In contrast, chronic pain due to a benign dis-
ease rarely, if ever, results from nociception; pharmaco-
logic, physical, and surgical management strategies must
be aimed at a different target. The patient with chronic
pain from a benign disease is usually not a candidate for
an ablative surgical procedure, in part because affective
and environmental factors are so likely to be playing a
major role. Those patients with chronic pain from an
injury to the peripheral or central nervous system may
be candidates for 11eurosurgical procedures, but further
deafferentation is rarely successful. Electrical sti1nula—
tion of the nervous system may be an effective alterna-
tive. It is always possible that additional knowledge
about the anatomy and physiology ofthe nervous system
may lead to new surgical procedures with higher success
rates.
There is little doubt that the results of an operation are
directly related to the surgeon's knowledge and skill. Ap-
propriate training and experience are the prerequisites
for neurosurgical procedures aimed at eliminating pain.
Most neurosurgeons have the necessary technical skills,
but few have had adequate experience dealing with pa-
tients with chronic pain. The majority of errors that lead
to unsuccessful outcomes do not occur in the operating
room but are made during the evaluation of the patient
by the surgeon. Short—term successes are too frequently
considered adequate reasons for major surgery; there are
few reported series with valid long—term analyses of out-
come. This is particularly true of the older, well—estab—
lished procedures.
In general, patients with chronic pain from a rnalig—
nant disease are better candidates for ablative surgical
procedures than those with chronic pain from a benign
disease process, in part because of the short life expec-
tancy common in patients who have a malignant disease
and because ablative procedures interrupt nociception.
which is the major component of pain due to cancer.
Affective and environmental factors are much more

likely to be significant components in chronic pain from
a benign disease.
Recent increases in knowledge about the endogenous
opioid systems have reduced the need for ablative surgi-
cal procedures in patients with cancer pain. The delivery
of narcotics directly to the spinal cord and brain by intra-
thecal and epidural routes has dramatically improved
pharmacologic pain management and has resulted in
fewer referrals for neurosurgical operations. Patients
with life expectancies of less than a few months are rarely
surgical candidates; epidural or intrathecal narcotics are
capable of providing pain relief for months and sorne—
times years.
A major problem for the neurosurgeon is the predic-
tion of lo11g—term results for the individual patient. Al-
though there are some series with adequate numbers to
make statistical predictions, how does this relate to the
individual patient? There do not, at present, appear to be
any reliable predictors of outcome. Psychiatric evalua-
tion of the patient with chronic pain may identify the
rare psychotic patient, who should not be offered sur-
gery, but it has not been very helpful in the usual patient
population. Psychological testing can identify the so-
matically preoccupied or hysterical personality types,
but standardized testing, such as the Minnesota Multi-
phasic Personality Inventory (MMPI) or McGill Pain
Questionnaire, does not appear to be useful in predicting
individual patient outcome from a pain—relieving proce-
dure. They do predict who is likely to return to work
after a discectoiny, but this is not the same as whose pain
will be abated by a cordotoiny.
It is clearly unwise to perform any operation on a se-
verely depressed patient, as pain behavior is likely to per-
sist independent of any nociception. The patient's past
history should not be ignored: excessive health care con-
sumption, prior unsuccessful surgeries, and the existence
of potent environmental reinforcers may be predictors of
surgical failure.
The role of nerve blocks in the selection ofpatients for
surgical procedures must be thoroughly understood. A
single nerve block is of little value; there are too many
extraneous factors that can inﬂuence the patient's re-
sponse. A carefully planned series of blocks can provide
valuable information about the anatomy and physiology
of the pain problem, but there has never been a study
that correlates the long—ter1n surgical result with the re-
sponse to local anesthetics used to block the somatic ner-
vous systern. Nerve blocks will identify the neryes or
roots that must be cut to isolate a peripheral region from
the brainstern or spinal cord; they can be used to evalu-
ate patient reliability by correlating duration of response
to the known effects of the agent utilized to perform the
block. Placebo responders are not known to have a more
or less favorable response to a surgical procedure. Nerve
blocks can also be used to allow the patient to experience
the expected numbness on a short—term basis. Some pa-
tients will prefer their pain to the numbness. Sy1npa—
PAIN / 295
thetic blocks do have more predictive value than somatic
blocks.
There are advantages and disadvantages to every oper-
ation and to all other forms of therapy for pain. What is
appropriate for one patient at a particular time may not
be optimal at another phase of the patient's 1nanage—
ment. Surgical procedures often must be performed in
conjunction with other modes of therapy if the patient is
to be fully rehabilitated. In general, destructive proce-
dures should not be considered until other therapies
have been evaluated. When indicated, surgical interven-
tion should not be delayed. That decision is the art of
neurosurgery.
ABLATIVE PROCEDURES
Peripheral Neurectomy
Although it is intuitively obvious that pain originating
from extremity or trunk pathology can be alleviated by
sectioning the peripheral nerves that go to the involved
part, this is, in fact, rarely a successful surgical strategy.
Theoretical advantages are greatly outweighed by practi-
cal failures. There are few indications for peripheral neu-
rectomy. It is occasionally helpful for the amputee who
has a neuroma in a weight—bearing area. Resecting the
nerve so that its new neuroma will lie in a more pro-
tected area can provide relief from a distressing pain syn-
drome. A traumatized nerve can develop a neuroma in
continuity; resection and neurorraphy or cable grafting
may provide both pain relief and restoration of function.
Meralgia paresthetica (painful dysesthesias in the distri-
bution of the lateral femoral cutaneous nerve) is usually
best managed without surgery. Pain following trauma to
the sensory branch of the radial nerve is notoriously re-
fractory to neurectomy. Neurectomy for a pain syn-
drome of vague etiology is not often successful.
If a peripheral neurectomy is to be undertaken, it is
imperative that the proximal stump be managed so as to
minimize the risks of postoperative neuroma pain. The
level of the 11eurectomy should be carefully planned so as
to avoid placing the site of transection in a weight—bear-
ing area. The literature is replete with nostrurns to pre-
vent the formation of a neuroma; I am unaware of any
conclusive evidence that such measures are beneﬁcial.
Intercostal neurectomies have fewer drawbacks than
sectioning an extremity nerve, yet they too are often only
of short—term value. Since nearly all peripheral nerves
are mixed, the motor loss is usually not an acceptable
trade for the relief of pain. Sensory nerve overlap, loss of
anesthesia because of peripheral nerve sprouting or cen-
tral reorganization, and anesthesia dolorosa can all con-
tribute to the high failure rate. Intercostal 11eurecto1ny
may occasionally be useful in the management of chest
wall pain resulting from a malignancy; it rarely, if ever,
helps postherpetic neuralgia or postthoracotomy pain. If
this procedure is to be utilized, preoperative assessment

296 / CHAPTER 13
with intercostal nerve blocks to determine the appro-
priate segmental patterns is valuable. Neurectornies
must be performed one or two levels above and below
the involved segments to eliminate peripheral sensory
overlap. Even more generous borders must be estab-
lished if chest wall pain results from a growing 1nalig—
nancy.
Sympathectomy
Two distinct types ofpain may be alleviated by syrnpa—
thectomy: those originating from tissue damage in the
thoracic and abdominal viscera, and those associated
with trauma to nerves or other injuries in the extrerni—
ties. The latter are now commonly classified as "syrn—
pathetically maintained pains."
Sympathectomy for visceral pain is analogous to so-
matic deaiferentation but has a much more favorable
outcome in properly selected patients (3). When syrnpa—
thectomy is contemplated to relieve the pain of a visceral
malignancy, it is important to rule put invasion of the
body wall structures and involvement of the somatic
nervous system. Even when the pain is totally relieved by
sympathetic blockade, subsequent tumor growth may
lead to body wall involvement and pain recurrence. The
pain associated with chronic, nonmalignant visceral pa-
thology such as angina pectoris, pancreatitis, renal pelvis
or ureteral distention, or dy smenorrhea can be alleviated
by appropriate Sympathectomy. However, the develop-
ment of new therapies for diseases of most of these or-
gans has largely rendered Sympathectomy obsolete; the
jgxception is pain associated with pancreatitis (4-5).
Causalgia, Raynaud's disease, and reﬂex sympathetic
dystrophy are the common pain states treated by syrnpa—
thectomy. The mechanisms for these sympathetically
maintained pains are debated, but the clinical observa-
tions have been repeated for over 50 years (6). Certainly,
ischemic pain is relieved by Sympathectomy, but that is a
result of increased blood flow. The dysesthetic pains as-
sociated with nerve injury or just trauma to a limb do not
seem to be related to blood flow and are often relieved by
Sympathectomy. Prompt Sympathectomy is more likely
to relieve the pain than that performed years after the
pain has started.
When a sympathetically maintained pain syndrome is
suspected, the first step is a reversible sympathetic block-
ade by local anesthetic block of the sympathetic chain or
by regional infusion of a peripheral agent such as gua-
nethidine (7). If a series of blocks provides temporary
relief, then a permanent Sympathectomy should be con-
sidered. In addition to surgical Sympathectomy, newer
strategies such as chemical or radiofrequency lesions of
the sympathetic chain should be considered (8).
Pains that include a dysesthetic component should be
evaluated by sympathetic block, whatever their sus-
pected etiology, as Sympathectomy may be an effective
treatment. Similarly, if there is a vasomotor or sudorno—
tor abnormality associated with chronic pain, a syrnpa—
thetic block should be part of the diagnostic assessment.
Unlike somatic neurectomy, Sympathectomy seems to
provide a good long—ter1n result. It has been my experi-
ence that the rnore an extremity pain syndrome resern—
bles true causalgia, the more likely it is that sympathec—
torny will be efficacious.
Spinal Dorsal Rhizotorny
One of the oldest neurosurgical procedures, spinal
dorsal rhizotomy has remained a commonly performed
operation in spite of its poor long—term efficacy. Its pri-
mary advantage over peripheral neurectomy is the spar-
ing of motor fibers and the absence, therefore, of signifi-
cant paresis. However, the sectioning of all of the dorsal
roots to an extremity in a human does render that limb
both anesthetic and unusable for any purposeful action.
Total dorsal rhizotomy to a limb is rarely a satisfactory
procedure unless the limb has already been rendered
functionless by a disease process. However, .extensive
dorsal rhizotomies of the upper cervical, thoracic, or
lumbar regions can be undertaken without significant
loss of function. Midline or bilateral pain requires bilat-
eral rhizotomies; in the sacral region this leads to loss of
sphincter control. Patients who have had urinary and
fecal diversionary procedures may be candidates for bilat-
eral sacral rhizotomy for relief of pelvic or perineal pain
(9). Dorsal rhizotomies seem to be of greatest value for
unilateral trunk pain, although some authors have
claimed good results in patients with persistent radicular
pain after lumbar discectorny (10-11). Most ofthe larger
series which have been reported indicate long—term suc-
cess rates of 25 to 50 percent (12).
Whether or not the addition of dorsal root ganglionec—
torny to dorsal rhizotomy will increase the long—term suc-
cess rate is unclear, as too few cases with long enough
follow—ups have been reported. The recognition of affer-
ent fibers in the ventral root and subsequent debate as to
whether or not these fibers actually entered the cord
through the ventral roots or made a U—turn to travel into
the cord through the dorsal roots has stimulated some
surgeons to routinely do ganglionectomies. The develop-
ment of a percutaneous technique for dorsal rhizotomy
by radiofrequency or cryoprobe techniques has extended
the potential utility of this operation to patients who
could not withstand a major operation. The percutane-
ous techniques are hazardous when performed in the
upper thoracic or thoraco—lumbar region because of po-
tential damage to essential arteries supplying the spinal
cord (12-14).
The evaluation of a patient for dorsal rhizotomy by
any method requires selective nerve blocks to identify
the involved segments. It is prudent to section at least
one level above and below the localized nerve roots be-

cause of sensory overlap. If the patient has an expanding
malignancy, additional roots above and below the in-
volved area should be resected. Dorsal rhizotomy is par-
ticularly likely to fail in postthoracotomy pain or post-
herpetic neuralgia; whether or not destruction of the
ganglion will increase success rates is unknown. Patients
who fail to get relief of pain after dorsal rhizotomy that
has made them anesthetic in the painful area rarely get a
good long—ter1n result when additional roots above and
below are sectioned. We do not yet have an adequately
performed analysis of dorsal rhizotomy to determine its
proper place in the neurosurgeon's repertoire of proce-
dures for pain relief.
Anterolateral Spinal Tractotomy
Commonly known as cordotomy, anterolateral spinal
tractotomy used to be one of the most frequently per-
formed operations for chronic pain. The original de-
scription was by Spiller and Martin in 1912. The innova-
tive studies of Mullan, Lin, and Rosomoff in the 1960s
have led to widespread acceptance of the percutaneous
methods utilizing radiofrequency current rather than
open surgical cordotomy (12,15 -18). The advent of in-
traspinal narcotics for the treatment of pain from cancer
has dramatically reduced the need for cordotomy.
Although the entire length of the spinal cord has been
a target for cordotomy, currently utilized percutaneous
techniques are done at C1-C2 laterally or in the midcer—
vical region anteriorly; open techniques are usually at
C1-C2 or in the upper thoracic area. The major advan-
tage ofcordotoiny is the selective loss of pain and ternper—
ature sensation that occurs contralateral to the lesion
site. There is no nerve block that mimics this type of
sensory loss, and patients, as well as many physicians, do
not understand the effects of cordotomy. Although care-
ful psychophysiological studies can demonstrate a vari-
ety of sensory changes, the patient will experience three
distinct phenomena if the operation is technically suc-
cessful: stimuli capable of damaging tissue no longer
elicit an unpleasant or alarming quality; thermal gra-
dients cannot be detected; and articulate patients will
describe a vague alteration in other sensory modalities.
Indeed, a few patients will complain of dysesthesiae and
paresthesiae, and a small percentage will have major
problems with "postcordoto1ny allesthesia," a pain syn-
drome that is refractory to treatment. Anterolateral cor-
dotomy does not lead to clinically significant alterations
in vibration, joint position, or light touch sensation, and
skeletal muscle function is unaltered.
A useful feature of cordotomy, when used in the pa-
tient with pain from a malignancy, is the extensive re-
gion of analgesia produced by an operation at a single
spinal level. This contrasts with dorsal rhizotomy, where
an additional laminectomy is required for each segment
to be denervated, and each rhizotomy only denervates a
PAIN / 297
narrow segment. In general, cordotomy can be expected
to produce analgesia beginning three to five segments
below the level of the spinal lesion, although a large C1-
C2 cordotomy may sometimes achieve analgesia up to
the level of the mandible. The extensive region of analge-
sia provides insurance against the local expansion of a
painful neoplastic process.
The results of cordotomy are highly correlated with ,
the surgeon's experience; they are also influenced by theI
duration of follow—up and the accuracy of reporting
(12,19). An overview of the reported cases and my own
personal experience suggest that about 85 percent of pa-
tients initially have good pain relief, but that there is a
significant drop—off at one year and beyond. Return of
pain often, but not always, parallels the loss of the sen-
sory changes induced by cordotoiny. Pain recurrence
seems to be more common after lesions that are not
complete, i.e., the entire contralateral body below the
lesion is not rendered analgesic. Cordotomy may also
fail to relieve pain if the sensory level is not high enough.
Additionally, about one—third of patients will deny pain
ipsilateral to the proposed cordotomy but will complain
of ipsilateral pain after the lesion is performed, probably
because of an unmasking of a minor pain when the more
severe pain is relieved by the operation. Such a patient
will require bilateral lesions.
The complications of cordotomy are quite well docu-
mented. Unilateral cordotorny will cause bladder dys-
function in about 5 percent of patients; bilateral cordot-
omy in about 20 percent. This may be permanent.
Sexual dysfunction in the male is common after bilateral
cordotomy but is very rare after a unilateral lesion. High
cervical cordotomy, especially bilateral, carries a low in-
cidence but high risk of respiratory failure (Ondine's
curse) (20). Postoperative testing with 5 percent inspired
CO2 will show if the normal stimulation of ve11tilation is
lacking. If so, the patient is at high risk to develop sleep
apnea; careful monitoring is required. Orthostatic hypo-
tension may develop after cordotomy and can be treated
with elastic stockings or mild vasoconstrictive drugs.
All of the above complications occur because of the
admixture of axons subserving different functions in the
anterolateral quadrant. In contrast, the occurrence of ip-
silateral paresis or even greater motor deficits is a sign of
technical error; the corticospinal tract has been dain-
aged. The incidence of temporary paresis is 10 to 15 per-
cent; long—term paresis occurs in about 5 percent of pa-
tients. Paraplegia is a rare complication of too large a
lesion or injury to a key blood vessel.
The indications for cordotomy are a function of the
patient's diagnosis and expected survival. Cordotomy is
best suited for patients with pain from a malignancy that
cannot be controlled directly by surgery, radiation, or
chemotherapy. Pain originating rostral to T6 requires a
cervical cordotomy; pain below this level can be con-
trolled by an upper thoracic cordotomy. Many neuro-

298 CHAPTER 13
surgeons always perform a cervical cordotomy regardless
of the pain level (20). Some argue that only the percuta-
neous method should be utilized; others prefer open pro-
cedures. The percutaneous technique requires frequent
utilization to be perfected; the casual operator cannot
expect the results published by the experts. Epidural or
mtrathecal narcotics are also highly successful in this
type of patient. They have largely become the initial
treatment of choice, with cordotomy being reserved for
failures of this strategy.
Cordotorny is not often effective for the treatment of
pain resulting from injury to the ce11tral or peripheral
nervous system (deafferentation or denervation pain).
Patients with injury to the nervous system are also much
more likely to develop postoperative complications such
as painful incisional site or postcordotorny allesthesia.
This operation rarely helps patients with dernyelinating
diseases, arachnoiditis, phantom limb pain, postparaple—
gic pain, or nerve root avulsion.
Bilateral or rnidline pain requires bilateral cordoto—
mies; this does raise the risk of complication. Such a
patient should be considered for intrathecal or epidural
narcotics or for cornrnissural myelotomy. Those who
frequently perform percutaneous cordotomy can offer
their patients this option and compete successfully with
alternative procedures, both for effective pain relief and
low risk of complications. Those who only occasionally
use this technique do not have as high a chance of such
salutary results.
Cornrnissural Myelotorny
This operation has been more extensively utilized in
Europe than in the United States. It is effective in reliev-
ing rnidline and bilateral pain, as it transects the decus—
sating fibers of the spinothalamic tract to produce a gir-
dle zone of analgesia. However, by mechanisms as yet
unclear, it also produces pain relief in segments caudal to
the region of analgesia that manifest no clinically detect-
able sensory loss. Long—term pain relief has not often
been reported, and myelotomy, like cordotomy, is best
utilized in patients with pain from a malignancy (21-
24). The long—terrn success rate in patients with cancer is
approximately 70 percent. Most often utilized in pa-
tients with abdominal or pelvic rnidline or bilateral pain,
myelotomy requires a larninectorny of T9 through LI
when cord segments LI through S5 are the sites of pain.
The operating microscope facilitates rnidline bisection of
the conus. Advantages over cordotomy are one opera-
tion for bilateral pain and a lower incidence of bladder
and leg weakness. Most patients will, however, have pos-
terior column deficits that are usually transient.
Percutaneous Cl myelotomy was initially described
by Hitchcock; pain relief without analgesia over most of
the body was observed (25). Only a small number of
patients have been reported, and this procedure certainly
has not been widely accepted. It deserves careful atten-
tion, especially in patients with widely disseminated
painful malignant diseases (26-27).
Facet Rhizolysis
Deriving from the work of Rees, who claimed excel-
lent results for back pain when he "sectioned the articu-
lar nerves to the facet joints," a radiofrequency percuta-
neous technique has been used in large numbers of
patients (28). Shealy first presented the radiofrequency
technique (29). However, not only did Rees‘ knife not
reach these nerves but the radiofrequency lesion has had
different target sites and little evidence exists that any
nerve was destroyed. The reported results have varied
from excellent to poor (12). Patients with previously un-
operated backs seem to have the best results, failed disc
operations have intermediate results, and those who
have already had a fusion ahnost never have good results
from facet rhizolysis. The procedure is performed under
local anesthesia and fluoroscopic control; complications
have been minimal. It does not appear to further damage
the lumbar spine and does not lead to additional scarring
about the nerve roots. The surgeon's faith in its efficacy
may be one of the major determinants of outcome.
Cranial Neurectorny
The accessibility of the peripheral nerves of the face
and scalp has made them the targets of surgical therapy
for at least 200 years. Trigeminal neurectorny was used
to alleviate tic douloureux in 1730; by 1900 avulsion of a
branch of the trigerninal nerve was standard therapy.
The early reports never claimed more than a 50 percent
one—year success rate, but this was the only treatment
available. The development of local anesthetics, alcohol
injection, anticonvulsants, and modern neurosurgical
techniques has greatly reduced the indications for periph-
eral neurectorny (30). A number of surgical procedures
forthe treatment of tic douloureaux are discussed below.
The reader is also referred to Chapter ll, "Trigeminal
and Glossopharyngeal Neuralgia and Hernifacial
Spasrn."
The advantages of trigerninal neurectorny include a
predictable area of complete sensory loss and low surgi-
cal morbidity. The disadvantages are the dense sensory
loss and about a 75 percent recurrence rate by one year
after surgery. Peripheral neurectornies are rarely success-
ful for cancer pain. They are never useful for atypical
facial pain or any other type of pain associated with
nerve injury or deafferentation. In a few patients with tic
douloureux, however, neurectorny may still be useful.
For example, if the tic pain is exclusively in the first

division, a supraorbital neurectomy may avoid any risk
of neuroparalytic keratitis and might, in some patients,
be preferable to gangliolysis.
Gangliolysis
As noted above, gangliolysis is usually preferable to
neurectomy as the primary strategy to relieve the pain of
tic douloureux (30). A very dense gasserian lesion may
also be helpful in the management of cancer pain (31).
Pains of unclear etiology or those due to deafferentation,
however, are rarely alleviated by gangliolysis. Three
methods of damaging the gasserian ganglion and thereby
alleviating the pain of tic douloureux now are in com-
mon use: radiofrequency thermal lesion, glycerol injec-
tion, and balloon compression. The existence of three
popular strategies suggests that each has some advan-
tages and drawbacks. The surgeon's preference seems to
be the major determinant of which procedure is used.
Percutaneous radiofrequency trigeminal gangliolysis
has been extensively utilized and many large series re-
ported (32). There are minor variations in technique
among neurosurgeons. In general, an insulated needle
with 2 to 8 mm of exposed tip carrying a thermister is
passed through the cheek i11to foramen ovale and the
position checked fluroscopically. Electrical stimulation
is used to localize the needle tip in the appropriate divi-
sion and radiofrequency current is utilized to heat and
partially destroy the ganglion and rootlets. Proper tech-
nique results in partial sensory loss, which is restricted to
the involved division(s). Analgesia is not a desired result.
This technique results in 80 to 90 percent one—year pain
relief in patients with tic douloureux; 60 percent five-
year relief is typical. The complication rate is less than
0.5 percent (33). The procedure can be repeated if neces-
sary with similar chance of success.
Glycerol gangliolysis involves the injection of small
amounts of a neurotoxic substance, glycerol, into the
trigeminal cistern (34). Although some have claimed su-
perb results without sensory loss, this has not been the
customary observation in recent years. It is my irnpres—
sion that glycerol gangliolysis is not as reliable as a radio-
frequency lesion and is not as likely to provide lo11g—term
pain relief (35).
Balloon compression of the gasserian ganglion is ac-
complished by placing a balloon catheter through a nee-
dle at the orifice of foramen ovale (36). It does not result
in a selective lesion and long—term follow—up data is not
yet adequate to permit meaningful contrast with other
techniques.
Cranial Rhizotomy
The afferent cranial nerves (trigeminal, glossopharyn—
geal, and nervus intermedius of the facial) may all be
PAIN / 299
sectioned in the subarachnoid space to render their sen-
sory fields anesthetic. Unilateral section of one or more
of these nerves can be valuable for the patient with face
and pharyngeal pain from a malignancy. Bilateral rlri—
zotornies are not prudent, as the patient is likely to have
a severe impairment of chewing, swallowing, and facial
sensation. The trigeminal and glossopharyngeal roots
and ganglia can be approached percutaneously and a le-
sion effected by radiofrequency current, thus sparing the
patient a major procedure (3 1,37). When cancer pain is
bilateral, the older literature suggests rhizotomies on one
side and a trigeminal tractotomy on the other to rnini—
mize loss of function. Other procedures, such as intraven-
tricular opioids, might be suggested today for such a pa-
tient.
Cranial rhizotomy for atypical facial pain or any other
form of facial pain not resulting from cancer, other than
tic douloureux, is most likely to fail (12).
Rhizotomy for tic douloureux used to be a commonly
performed operation, and large series have been pub-
lished. Partial trigeminal rhizotomy offers a 75 percent
long—term pain relief with a 5 percent risk of painful par-
esthesiae or anesthesia dolorosa. Total trigeminal rlri—
zotorny has a 90 percent long—term success rate but a 10
percent risk of painful paresthesiae or anesthesia dolo-
rosa. The surgical technique (via the middle fossa or pos-
terior fossa) does not appear to influence the results.
Whenever the first trigeminal division is rendered anes-
thetic, there is a risk of neuroparalytic keratitis. Trigemi-
nal rhizotomy is no longer a primary procedure for tic
douloureux, as it has been replaced by gangliolysis and
microvascular decompression.
Microvascular Decompression of the Trigeminal Nerve
Microvascular decompression of the trigeminal nerve
(MVD) is an exceedingly effective method of treating the
tic douloureux patient who has failed medical manage-
ment (38). By means of a retromastoid craniectomy, the
trigeminal nerve is visualized and mechanical cornpres—
sion in the juxtapontine area is relieved. Most patients
have a loop of the superior cerebellar artery impinging
upon the nerve; occasionally it is the anterior inferior
cerebellar artery; rarely it is another artery or a vein. A
few patients have a neoplasm or arteriovenous rnalfor—
mation compressing the nerve. MVD has the great ad-
vantage of producing no sensory loss; its major disad-
vantage is the magnitude of the surgical procedure
requiring general anesthesia and several days of hospital-
ization.
Although it was originally hailed as a curative opera-
tion for tic douloureux, more recent data has indicated
that patients do often relapse 5 to 15 years after surgery
(Fig. 2) (39). The conceptual basis of this operation has
also been attacked. Nonetheless, the large numbers of

300 / CHAPTER 13
cases reported by many authors permit some meaningful
generalizations about this operation. Pain relief does not
require clinically detectable sensory loss. The mortality
rate is l to 2 percent; the complication rate is about 5
percent. About 10 percent of patients fail to get initial
relief, and an additional 10 percent will experience recur-
rence of pain in the first postoperative year. After the
fifth postoperative year about 3 percent of the patients
per year will have a recurrence.
MVD is certainly preferable to trigeminal rhizotomy
in the treatment of tic douloureux. It does not appear to
be useful for any other painful condition of the trigerni—
nal distribution. Similar cross—cornpressing lesions have
been described for the glossopharyngeal nerve and the
nervus interrnedius, and implicated in tic douloureux
resulting from their sensory distributions. If MVD is
planned and no lesion is found, a rhizotomy should be
undertaken.
Medullary Trigeminal Tractotomy
The feasibility of dividing the descending trigeminal
tract in the medulla was demonstrated by Sjoquist in
1938 (40). In the past 50 years, new techniques have
made tractotomy less hazardous and more likely to pro-
vide pain relief. The pain and temperature fibers from
the entire orofacial region travel in the descending tri-
geminal tract, so it is possible to alleviate pain from fa-
cial, oral, and pharyngeal structures by lesions in this
tract.
Open descending trigeminal tractotomy is performed
through a C1-C2 laminectomy; the optimal lesion site is
10 to 12 mm caudal to the obex. Accurate anatomic
localization requires the operating microscope; physio-
logic confirmation is obtained by recording from the cer-
vicornedullary junction the responses evoked by sti1nula—
tion of the median nerve (fasiculus cuneatus) and
trigeminal cutaneous branches (descending tract) (41).
Lesions can be made to produce analgesia selectively in
FIG. 2. Kap|an—Meier plot ofthe proba-
bility of remaining pain—free over time
following microvascular decompres-
sion (MVD). Thirty-six patients under-
went 36 MVD procedures. Minor and
major refer to the magnitude of recur-
rence of pain. Patients were censored
at the following rate: year 7: 2 pa-
tients; year 8: 1 0 patients; year 9: 25
patients; and year 10: 33 patients.
(From reference 39, with permission.)
the glossopharyngeal or nervus intermedius territories
(42). This operation leads to the selective loss of pain and
temperature sensation but does not affect touch or posi-
tion sense.
A percutaneous method for stereotactic trigeminal
tractotomy has been described by Hitchcock (43) and by
Schvarcz (44). Their lesion also destroys the trigeminal
nucleus, and they claim that it is successful for both deaf-
ferentation and cancer pains. Published results by others
are nonexistent, but these authors claim that about half
of the patients have gotten long—terrn relief.
Trigerninal tractotomy is a valuable secondary proce-
dure for the patient with tic douloureux who has failed to
respond to rhizotomy or rnicrovascular decompression.
Pain from orofacial malignancies can be successfully
controlled; it may also have value in the treatment of the
deafferentation pains that afflict the face.
Thalamotorny
In spite of its theoretical attractiveness and apparently
good short—term results, stereotactic thalarnotorny rarely
provides even one year of pain relief (45,46). Its use,
therefore, is best restricted to patients with short life ex-
pectancies, as seen in cancer pain. Assessment of long-
terrn results is hampered by differing nomenclature, lack
of anatomic proof of target site, wide range of etiologies
for the patient's pain, and, all too frequently, inadequate
follow—up. Although the development of CT and MR
scanning has dramatically improved stereotaxis for
biopsy of lesions, it has not significantly improved target
location for ablative or stimulation operations. Morbid-
ity and mortality are reported to be low, but thalamot—
orny should probably be restricted to tertiary centers pos-
sessing significant experience with stereotaxis for pain
and other purposes such as movement disorders and
biopsy of lesions.
The most common target sites have been the medial
posterior nuclear masses: the centrernedian, parafasicu—

laris, intralarninar nucleus, and pulvinar. All of these
regions receive fibers from the nonspecific ascending sys-
tems and project to a wide range of subcortical and corti-
cal association areas. Another target group has been the
dorsornedial and anterior thalarnic nuclei, which project
to lirnbic and frontal structures. Lesions in these areas
seem to alter the affective response to noxious stirnula—
tion, in contrast to the posterornedian lesions, which
alter the perception of pain itself (47). Lesions in these
areas usually need to be bilateral to have any lasting ef-
fect.
Tasker reviewed the literature and his own experience
with thalarnotornies for pain (46). Approximately 60
percent of the patients with pain secondary to tissue darn-
age or cancer got some pain relief; only 25 percent of the
patients with dysesthetic pains secondary to nervous sys-
tem injury were relieved. Follow—up periods were vari-
able for this heterogeneous group of patients.
Thalarnotomy is clearly not a primary procedure for
relief of either cancer pain or that associated with injury
to the nervous system. When other, more focal surgical
procedures as well as alternative strategies for pain inan-
agement have failed, it can be a useful procedure, particu-
larly for cancer pain.
Cingulumotomy
The unsatisfactory experience with frontal leucotorny
for pain led to the development of cingulumotomy by
Foltz and White (48). This procedure has been most ex-
tensively studied by Ballantine and his associates (49).
Ci11gulumotomy appears to be effective in attenuating
the exaggerated suffering that some chronic pain pa-
tients rnanifest. It does not alter nociceptive thresholds
and does not lead to cognitive defects. This operation is
also valuable for patients with severe phobic neuroses
who have failed to respond to other therapies. Cingulu-
motomy is an affect—altering operation that has replaced
frontal leucotorny. Bilateral lesions are performed ster-
eotactically in the anterior cingulurn bundles under local
anesthesia. Cingulumotomy also has been performed in
conjunction with anterior thalarnic and frontal lesions.
The public protest against any type of psychosurgical
procedure has all but eliminated this operation in the
United States; it is still frequently used in Sweden and
other European countries. It can be of great value to the
properly selected patient whose suffering is out of pro-
portion to the apparent noxious stimulus and in whom
no other method of pain relief has succeeded.
Hypophysectomy
Ablation of the pituitary gland has been effective ther-
apy for the relief of pain resulting from osseous rnetas—
tases from carcinoma of the breast or prostate. Its value
in other neoplasms is unproven. Hypophysectorny
PAIN / 301
seems to be of greatest value in postmenopausal women
with breast carcinoma who have previously dernon—
strated a favorable response to oophorectorny or hor-
monal therapy, who do not have vital organ involve-
ment, and who have survived many years between the
original diagnosis and dissemination. About 50 percent
of the women with breast carcinoma or men with pros-
tatic carcinoma will experience pain relief: it is not al-
ways correlated with signs of tumor regression (50). Hy-
pophysectorny can be accomplished transcranially. but
the transsphenoidal approach appears to have a lower
morbidity and mortality and a shorter period of hospital-
ization.
Electrical Stimulation
Electrical stimulation of the skin, peripheral nerves,
spinal cord, and brain has become an increasingly corn-
mon method of treating chronic pain during the past 20
years. Skin stimulation [transcutaneous nerve stirnula—
tion (TNS) or transcutaneous electrical nerve stirnula—
tion (TENS)] has been extensively used to treat chronic
pain owing to benign diseases. It will, in some patients,
ameliorate both acute and chronic pain but has not been
very effective in cancer pain. A spin—off of the space—age
need for microelectronics, spurred on by the Melzack—
Wall gate hypothesis, TNS has been a very useful nonin-
vasive treatment modality.
Controlled studies of its utility have been few, and
there are no diagnoses associated with a high or low
chance of success (51). Long—term relief will be obtained
in about 25 percent of unselected patients with chronic
pain associated with benign diseases. Stimulation is most
effective when delivered in the painful area; if the pa-
tient's sensory loss is profound this strategy will not
work. There are virtually no complications of TNS, but
the patient does require training for its optimal use.
Peripheral nerve, spinal, and brain stirnulators all re-
quire a surgical procedure, and they have not been as
extensively utilized. The neurophysiologic basis for pain
relief with electrical stimulation is unknown, but periph-
eral nerve stimulation, spinal cord stimulation, and lat-
eral thalarnic—internal capsule stimulation probably have
a common underlying mode of action, as they all require
that paresthesiae be felt in the painful area if stimulation
is to be effective. They probably do not involve the en-
dogenous opioid system.
Spinal cord stimulation, originally called dorsal col-
umn stimulation (DCS), was the first to have widespread
clinical trials and is still the most common form of irn—
planted stimulation. There are two ways of implanting
the spinal electrode: percutaneously, via an epidural nee-
dle, and open, requiring a small larninotorny. Although
the percutaneously inserted electrode obviates the need
for a surgical procedure, problems with electrode migra-
tion and impedance changes have plagued this system.

302 / CHAPTER 13
Larger electrodes inserted through a larninotorny have
proved more durable. The lead wires are tu1111eled under
the skin to either a radio—frequency coupled receiver or a
battery driven stimulator very similar to a cardiac pace-
maker. The forrner requires that the patient carry a stirn—
ulator box and antenna affixed to the skin over the re-
ceiver; the latter is fully programmable via telemetry. It
has been my experience and that of most other surgeons
who have reported their series that about one—half of the
patients report initial adequate pain relief but that only
one—half of these will have adequate pain relief at follow-
up one year later (52). Hence, one—fourth of those
deemed suitable for spinal cord stimulation will be long-
term successes. The complication rate is low and no ad-
ditional neurological deficits are required to obtain pain
relief, so spinal cord stimulation has advantages over ab-
lative surgery.
The optimal parameters for stimulation vary among
patients; some report pain relief only during stimulation;
others have pain relief for hours from brief intervals of
stimulation. Good results have been reported with pain
due to nociception or to nerve and spinal cord injury
(53-55). Other authors have reported the best results
with postherpetic neuralgia and vasculopathic pain and
the poorest results with cancer pain and spinal cord in-
jury pain (56). It is difficult to identify diagnostic groups
that are likely to respond more or less favorably.
Peripheral nerve stimulation (PNS) has not been as
commonly utilized as spinal cord stimulation, but the
results appear to be at least as good (57). An electrode is
placed around the nerve to be stimulated and connected
to a stimulator device as described above for spinal cord
stimulation. Stimulation must be perceived in the pain-
ful area if the device is to be effective. PNS is useful in
patients with pain owing to peripheral nerve injuries.
Stimulation of the brain for pain relief has been valu-
able in a small number of patients (58). A multicontact
electrode is inserted stereotactically i11to the target area
under local anesthesia. After a trial period with extemal—
ized lead wires, the electrodes are connected to an irn—
planted stimulator of either the radio—frequency coupled
type or the fully implanted pacemaker type.
Two target areas arecornrnonlyutilized: rostral mesen—
cephalic periventricular gray (PVG) or lateral thalamus-
internal capsule (1C). Stimulation of the former appears
to activate a downstream inhibitory system that reduces
the responsiveness of the lamina V neurons to nocicep-
tive input. This is the descending inhibitory system in-
volved in opiate analgesia, and PVG stimulation rnani—
fests habituation and is blocked by naloxone. Other
mechanisms may also be involved. This target area ap-
pears to be optimal when the chronic pain results from
tissue damage and not from deafferentation.
Stimulation of the lateral thalamus-internal capsule is
notblocked by naloxone and does not show habituation.
It does not appear to involve endorphins or downstream
opioid modulation; its mechanism of action is unknown
but probably similar to spinal cord stimulation. It is not
as effective against pain from tissue damage but is useful
for deafferentation pain seen after injury to the periph-
eral or central nervous system. Effective stimulation of
the internal capsule requires that the patient perceive
paresthesiae in the painful area. Complications of brain
stimulation are few; electrode migration and loss of ef-
fective stimulation can occur. Stereotactic procedures
require specialized resources and skills that are not
widely disseminated in the neurosurgical community.
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CHAPTER 14
Movement Disorders
Princi les 0fNeur0surgery,
edite by Robert G. Grossman. Rosenberg © 1991.
Published by Raven Press, Ltd., New York.
Robert G. Grossman and Winifred J. Hamilton
Introduction, 305
Stereotactic Thalamic Lesioning, 305
Neurophysiological Basis, 305
Indications, 307
Stereotactic Technique and Considerations, 310
INTRODUCTION
A number of movement disorders can be ameliorated,
sometimes even abolished, by neurosurgical procedures.
The most commonly performed procedure is the stereo-
tactic placement of a lesion in the ventrolateral thala-
mus. Such a lesion usually abolishes the tremor of Par-
kinson's disease or essential tremor, and it can reduce
the rigidity associated with Parkinson's disease (1,2). A
single ventrolateral thalamic lesion is less successful for
treating hemiballismus, dystonia, or toiticollis, although
in individual cases, it sometimes produces significant re-
lief. More extensive thalamic lesioning, or selective
nerve and muscle sectioning in the case of torticollis, can
sometimes lessen these dyskinesias although complete
abolition is generally not possible. Several other neuro-
surgical procedures have been attempted for particular
dyskinesias, with varying degrees of success. These in-
clude chronic electrical stimulation, implanted pumps
for the chronic release of neurotransmitters or 1nedica—
tions, and the transplantation of neural tissue.
STEREOTACTIC THALAMIC LESIONING
The use of thalamic lesioning in the treatment of
movement disorders has largely developed through the
study and treatment of Parkinson's disease. Parkinson's
disease is the most prevalent and the most extensively
studied of the movement disorders. It is estimated that in
R. G. Grossman and W. J. Hamilton: Department of Neuro-
surgery, Baylor College of Medicine, Houston, Texas 77030.
305
Other Procedures, 314
Nerve—Sectioning Procedures, 314
Chronic Electrical Stimulation, 3 15
Neurotransmitter Augmentation, 315
References, 316
the United States alone there are 40,000 new cases each
year and a cumulative total of approximately 300,000
cases at any one time (3,4).
NeurophysiologicalBasis
Any attempt to understand the efficacy of a thalamic
lesion in ameliorating the tremor of Parkinson's disease
must grapple with a divergent array ofphysiological, ana-
tomical, and clinical evidence; this evidence, although it
suggests certain models by which abnormal movements
may be generated, also reveals how little is understood
about the pathophysiology underlying the movement
disorders. The primary pathology observed in Parkin-
son's disease is the deterioration of dopaminergic neu-
rons in the midbrain, especially in the substantia nigra,
and a concomitant deterioration of the dopaminergic
pathways projecting to the striatum (5-7). The etiology
of this deterioration is not known. Dopaminergic projec-
tions from the midbrain have an inhibitory influence on
the striatum, and it has therefore been suggested that the
loss of this influence may disinhibit the striatum and
thereby lead to tremor (8). Also, dopamine inhibits stria-
tal production of acetylcholine; therefore, loss of dopa-
mine leads to excess acetylcholine, which presumably
contributes to the symptoms of Parkinson's disease.
There is evidence to suggest that the mechanisms un-
derlying tremor and bradykinesia are fundamentally dif-
ferent. Surgery is very effective for tremor, but it has little
or no effect on bradykinesia. Conversely, levodopa or
carbidopa is effective for bradykinesia but has less effect
on tremor. Hoehn and associates found decreased levels

306 / CHAPTER 14
of dopamine catabolites in the urine ofpatients with Par-
kinson's disease and noted that these levels correlated
with the degree ofbradykinesia, rigidity, and mental dete-
rioration observed. They found no correlation between
the levels of dopamine catabolites and tremor (9).
The complexity of the pathophysiological substrate of
Parkinson's disease is underscored by the fact that
tremor can be relieved to a greater or lesser degree by a
lesion in several cortical and subcortical areas—includ—
ing cortical areas 4 or 6, the globus pallidus, the ventro—
lateral thalamus, and the ansa and fasicularis lenticularis
(10-12). Of these sites, most surgeons now prefer placing
a lesion in the ventralis intermedius (VIM) of the ventro—
lateral thalamus (according to Hasslcr's terminology; see
Fig. 1). Such a lesion is effective in ameliorating tremor
and creates few, if any, secondary neurological deﬁcits
(1,2, 13). In addition, a VIM lesion ameliorates rigidity in
some parkinsonian patients (1,2), although a slightly
more anterior lesion, in the ventralis oralis posterior
(VOP) or the ventralis oralis anterior (VOA), is often
advocated for the treatment ofpatients in whom rigidity
predominates (5,8,14). Although long—lasting relief from
the tremor of Parkinson's disease has been reported fol-
lowing a VIM lesion (1,2), the lesion does not affect the
progression of bradykinesia.
Although it is unclear how a VIM lesion alters the
pathophysiology that leads to the tremor of Parkinson's
disease, several aspects of the neurophysiology of the
ventrolateral thalamus pertain to this question. First,
unit recordings made in the VIM nucleus of the thala-
mus have revealed rhythmic bursts that are synchronous
RG. 1 . Division of the ventrolateral thalamus according to
Ihe terminology established by Hassler. Abbreviations: CM =
centrum medianum; Gpe = external segment of globus palli-
dus; Gpi = internal segment of globus pallidus; LPO = lateral
polaris; Put = putamen; Vce = ventralis caudalis externus;
Vci = ventraiis caudalis internus; VIM = ventralis intermedius;
VOA = ventralis oralis anterior; VOP = ventralis oralis poste-
rior. (From reference 1 7, with permission.)
with the tremor in patients with Parkinson's disease (15).
The importance of this area in the generation of tremor
is further supported by the fact that stimulation in the
VIM nucleus will alter the tremor, either driving the
tremor or, less commonly, suppressing it (14,15). Some
researchers have suggested that the neurons of the VIM
nucleus may autogenously generate the discharge and
that therefore destruction of these neurons stops the
tremor, but it is also possible, for the following reasons,
that the lesion interrupts and alters the complex neural
circuitry by which movements are monitored and regu-
lated.
Lesions made in the ventrolateral thalamus that are
effective in relieving tremor and rigidity appear to in-
terrupt two pathways within the subcortical circuitry,
Which eventually drives cortical firing (Fig. 2) (5,16,17).
One is the pallidothalamic pathway extending from the
globus pallidus via the ansa lenticularis of the fields of
Forel to the anterior—inferior aspect (the area of the
VOA) ofthe ventrolateral thalamus and on to the cortex,
particularly area 6. The other pathway includes fibers
from the contralateral cerebellum that pass through the
thalamic peduncle into the more posterior parts of the
ventrolateral thalamus (VIM—VOP) and continue on to
area 4 of the cortex. It has been suggested that the first
pathway may be associated primarily with rigidity,
whereas the second may be associated primarily with
tremor( 17).
Hassler has proposed that depression of the fusimotor
(gamma) system may underlie the tremor and rigidity of
Parkinson's disease and that a ventrolateral thalamic le-
sion, by reducing thalamic inhibition of the fusimotor
system, may help to restore proper fusimotor activity
(17). In support of this general hypothesis, Stern and
Ward produced a parkinsonian—like state in the monkey
in two ways: by administering reserpine and by making
lesions in the ventromedial tegmentum of the mesen—
cephalon (18,19). Both models produce decreased levels
of dopamine in the striatum and a decrease in gamma
efferent activity with resultant alpha phasic and tonic
hyperactivity. They postulate that the experimental le-
Sensory Motor Cortic ospinal
Systems Cortex Tract
Venn-olater-a1 Caudate Nucleus
Globus Pallidus
Thalamus and Putamen
Cerebellum S"b'ha'am'C Substantia Nigra
Nucleu s
Midbrain
FIG. 2. Schematic presentation of the major interconnec-
tions between the motor cortex and the subcortical motor
areas. (From reference 27, with permission.)

sions disturbed the balance between the alpha and
gamma motor neurons, giving rise to a preponderance of
alpha tone. Similarly, they argue, Parkinson's disease
may alter the balance between the alpha and gamma
motor systems, and a thalamic lesion may help to restore
the normal balance (20). Further support for the theory
of gamma inhibition is provided by the fact that chlor-
promazine, in appropriate doses, inhibits the gamma
system. Syndromes resembling Parkinson's disease are
produced in some patients overtreated with chlorproma—
zine(2 1) .
However, other studies have demonstrated a height-
ened, rather than a depressed, level of fusimotor activity
in patients with Parkinson's disease (12). This finding is
supported by studies that have revealed a change in the
mode of maintained voluntary innervation after a ven-
trolateral thalamic lesion, suggesting a shift from alpha-
garnrna coactivation to a predominantly alpha—driven
muscle innervation (22). Yanagisawa and associates
found that bilateral ablation of the sensory—motor cor-
tex, cerebellum, and rnedullary pyramids failed to re-
duce the muscle spindle's response to thalamic stirnula—
tion, whereas bilateral lesions in the midbrain
tegmentum did. These findings suggest that the facilita-
tion is mediated by a pathway from the ventrolateral
thalamus to the reticular formation (23).
Lieberman, Copack, and Oilman noted a decrease in
fusimotor activity leading to a decrease in spindle affer-
ent responses following a ventrolateral thalamic lesion
(24). This decrease in response deprives the alpha neu-
rons of a strong facilitatory influence and, they postu-
late, would result in a decrease of previously hyperactive
alpha activity and a concomitant reduction in muscle
tension. Their findings support those of Yanagisawa and
associates by suggesting that the ventrolateral thalamus
exerts a net excitatory influence on the fusimotor neu-
rons, rather than a net inhibitory effect as proposed by
Hassler and by Stern and Ward.
Indications
Parkinson ’s Disease
Between 1950 and 1968, surgical neuroablative proce-
dures played a major role in the treatment of Parkinson's
disease. With the introduction oflevodopa in 1968, how-
ever, utilization of surgical treatment substantially de-
clined (25). More recently, improvements in stereotactic
surgery and a growing understanding of the limitations
and side effects of levodopa therapy have renewed inter-
est in the use of surgery for patients with Parkinson's
disease (5,26).
Although medical control of symptoms is generally
attempted first, some clinicians believe that surgery
should be used to treat the early—appearing symptoms of
MOVEMENT DISORDERS / 307
tremor and rigidity in relatively young patients. This
way, levodopa can be reserved for the usually later—de—
veloping and more debilitating symptom of bradykine—
sia, for which there is presently no other effective treat-
ment (1,5). Studies have also found that patients with a
pre—existing thalamotomy suffer fewer side effects from
levodopa therapy. Not only do these patients appear to
have fewer levodopa—induced dyskinesias in the limbs
contralateral to the lesion (1), but thalamotomy appears
to lessen the "on—off" syndrome associated with contin-
ued levodopa therapy (5). Narabayashi and associates
noted that levodopa—induced dyskinesias were largely
eliminated by a lesion in VIM—VOP (14). Nagaseki and
coworkers reported that, in a series of 27 patients oper-
ated on for Parkinson's disease, the amount of levodopa
necessary to control symptoms after thalamotomy was
approximately one—half of that necessary before sur-
gely (2).
The ideal candidate for surgical treatment of Parkin-
son's disease is a patient who (1) has unilateral tremor
and little or no rigidity, bradykinesia, mental deteriora-
tion, or speech and gait disturbances; (2) is unresponsive
to or intolerant of drug treatment; and (3) has no general
medical risk factors that would increase the risk of sur-
gery. The decision to offer surgery to less—than—ideal can-
didates—patients with rigidity, bradykinesia. and ill-
nesses common in older patients—should be based on a
careful weighing of the benefits and risks for the individ-
ual patient. Unilateral tremor can be eliminated by a
VIM lesion in 85 to 90 percent of patients and can be
ameliorated in the remainder (1,2). Rigidity appears to
be lessened in some patients following a VIM lesion (2).
However, as noted earlier, a lesion slightly anterior to the
VTM nucleus, in the VOA—VOP complex, is usually
more successful in relieving rigidity than is a VIM lesion
(5,8,15). Kelly and Gillingham found that 88 percent of
58 patients who had significant rigidity preoperatively
had no signs of rigidity two years after VOA thalamo-
tomy (1,8). Most investigators report little or no irnprove—
ment in bradykinesia following a thalamotomy. Masked
facies, speech and swallowing impairments, festinating
gait, and intellectual impairment also fail to respond to
thalamotomy and may even be aggravated by the sur-
gery (12). Younger patients respond better than older
patients, with older patients experiencing an increased
incidence of postoperative confusion and disturbances
of balance (12,27).
For many patients, a VIM lesion provides long—term,
possibly even permanent, relief from tremor on the side
contralateral to the lesion. Tremor, usually mild and not
disabling, may recur gradually in a percentage of patients
in the years following surgery. In Kelly and Gillingham's
long—term follow—up of 57 patients who underwent thala-
motomy for tremor, 90 percent had no tremor two years
after surgery, 73 percent had no tremor after six years,
and 57 percent had no tremor after 10 years (1). Their

308 CHAPTER 14
findings with regard to rigidity were similar, with 86 per-
cent having no evidence of rigidity on the contralateral
side two years after surgery and 55 percent having no
evidence of rigidity 10 years after surgery. Nagaseki and
associates have also followed patients operated on for
tremor for an extended period (mean 6.58 years). Their
late results were essentially identical to the early results,
with 92 percent of both groups of patients displaying
satisfactory relief (mild or no residual tremor) on the side
contralateral to the surgery (2). The occurrence or pro-
gression of tremor and rigidity on the ipsilateral side was
unaffected by surgery.
For patients with bilateral tremor and rigidity, a sec-
ond thalamic lesion on the opposite side appears to be
less effective than the first lesion and is more apt to be
followed by neurological deficits, especially dysarthria
and disequilibrium (5,12,28). Cooper and associates re-
ported approximately 70 percent relief of tremor and
rigidity following a ventrolateral thalamic lesion on the
second side, in contrast to 90 percent relief following the
first lesion (29). To avoid some of the complications of
bilateral surgery in patients with bilateral Parkinson's
disease, Benadid and coworkers have used a combined
technique of thalamotomy for the most disabled side
and continuous VIM stimulation for the other side, us-
ing stereotactically implanted electrodes connected to
subcutaneous stimulators (30). Stimulation at 130 Hz
strongly decreased the tremor but did not suppress it as
completely as thalamotomy.
Intention Tremor
Tremor activated by movement—intention tremor—
may occur in victims of severe closed head injury and in
patients with multiple sclerosis. Although the tremor is
usually not the most disabling ofthe neurological deficits
encountered in these two groups of patients, it adds to
the overall disability and often interferes significantly
with activities of daily living. This tremor can be arne—
liorated by a VIM lesion, but complete cessation of the
tremor cannot be expected in most individuals, probably
because of the widespread nature of the subcortical le-
sions in these conditions (31,32). The size of an effective
lesion is generally larger than that required for treatment
of Parkinson's disease.
Bullard and Nashold reported on the results following
a ventrolateral thalamic lesion (in VIM, sometimes ex-
tending into the VOP) in 11 individuals with movement
disorders following a severe head injury (33). Of these,
seven had intention tremor, nine hemiballistic rnove—
ments, two choreoathetoid movements, and two truncal
ataxia. All 11 had preoperative dysarthria, which ranged
from mild to severe. Postoperatively, all had immediate
improvement in their tremor, although in two the im-
provement was not considered functionally significant.
In four of nine patients available for follow—up examina-
tion, the tremor continued to improve in the interval
since surgery. Five of the six patients who had a left—sided
procedure and one of five patients with a right—sided pro-
cedure had significantly worsened dysarthria following
surgery. In all but two, this dysfunction later improved.
These results generally agree with those of Andrew,
Fowler, and Harrison who found that, following stereo-
tactic thalamotomy, in eight patients with posttraumatic
tremor, all showed improvement (32). The lesion was
designed to be situated in the VIM, close to its boundary
with the ventralis caudalis externus (Vce). In two pa-
tients a second lesion was necessary to stop the tremor,
and in five patients a third lesion was necessary. The
second and third lesions were generally placed more ante-
riorly, in the oralis externus (the external aspect of
Hassler's VOA—VOP). Resting and postural tremors
were abolished in all eight patients, as were myoclonic
jerks. Intention tremor was eliminated in one patient
and greatly reduced in the other seven. All showed
marked functional improvement. Dysarthria and ataxia
tended to be worse immediately after surgery but to
abate in the subsequent weeks.
Cooper has reported lasting abolition of intention
tremor 10 years following surgery in 72 percent of 32
patients with multiple sclerosis (12). In this series, spastic-
ity worsened following surgery in two patients with pre-
existing spasticity, but other symptoms of cerebellar dys-
function (dysarthria, ataxia, hypotonia) were unaffected.
Krayenbiihl and Yasargil have reported similar results
(34). The preferred target appears to be the posterior
aspect of the VIM nucleus, extending just into the Vce
nucleus, although some surgeons advocate a subthala—
mic target (5). Acute exacerbation of the visual, spinal,
and cerebral symptoms of multiple sclerosis has been
reported following thalamotomy; dexamethasone dur-
ing the immediate postoperative period appears to re-
duce this complication (5).
Intention tremor as a sole symptom, so—called "essen-
tial" trernor, can usually be eliminated by a VIM lesion,
although the lesion must generally be larger than for
treatment of Parkinson's disease.
H emiballismus
Hemiballismus is characterized by violent ﬂinging
motions that involve the extremities on one—half of the
body, although it is usually most marked in the arm.
Most instances occur in the elderly, usually following an
infarction in the subthalmic nucleus, but cases have been
recorded in association with neoplasms, granulomas,
head injury, and multiple sclerosis (33,35). Although rel-
atively few patients have been operated on for hemibal-
lismus, a VIM lesion appears to be effective for 50 to 60
percent of patients with this disorder (12,36). In Bullard
and Nashold's series of 11 patients with dyskinesias sec-

ondary to severe head injury, nine displayed hemiballis—
mic movements. Following thalamotomy, five showed
marked improvement, three moderate improvement,
and one mild improvement (33).
Dystonla
Dystonia is a condition characterized by sustained
muscle contractions that lead to twisting and repetitive
movements and often to abnormal posturing. Its mani-
festation and clinical course are highly variable, suggest-
ing that various etiologies may be involved. The best
surgical results have been obtained in posttraumatic
hemidystonia in which CT or MR images show a struc-
tural lesion, such as infarction in the basal ganglia (37).
The ameliorating effect is greatest for dystonic move-
ments of the hand, less for leg movements, and least for
dystonia of the trunk. Interestingly, the effect of surgery
for dystonia tends to increase over one to three months
following surgery, as opposed to the immediate benefit
observed in patients with parkinsonian tremor. Multiple
thalamic lesions covering several nuclei are generally nec-
essary to ameliorate dystonia. In addition to a lesion in
the VIM nucleus, a lesion is often placed in the centrum
medianum (CM) nucleus (37). particularly if the dys-
tonia is driven by arousal or sensory activation. In other
patients, lesions in the VOP and VOA of the thalamus
may be necessary.
Torticollis
Torticollis differs from the other movement disorders
in that it is confined to the muscles of the head and neck
—primarily the sternocleidomastoid, trapezius, and
splenius capitus muscles, although other muscles may be
involved as well. It is characterized by sustained muscle
contractions that commonly force the head into an ab-
normal posture, usually displaying some degree of rota-
tion and retroﬂexion, anteflexion, lateral flexion, or any
combination ofthese. Although torticollis may be a form
of dystonia confined to the head and neck, this is not
clear. Torticollis is, in general, difficult to ameliorate by
medical or surgical means. Recently, the injection ofbot—
ulinum toxin into the affected muscles has produced im-
provement in some patients (38). Thalamotomy is gener-
ally not indicated for torticollis except in patients in
whom it is a clear symptom of more generalized dystonia
and in whom other approaches have not provided suffi-
cient relief. For most patients with medically intractable
torticollis, a nerve—sectioning procedure that denervates
the anterior roots of the upper cervical nerves and some-
times the spinal accessary nerve—and in some cases a
combination of this procedure and selected myotomies
—can provide significant relief (5,27,39,40). These pro-
MOVEMENT DISORDERS / 309
cedures for the treatment of torticollis are discussed to-
ward the end of this chapter.
In patients in whom thalamotomy has been per-
formed for torticollis, the results have been variable.
Long—term relief generally requires bilateral lesions,
which increase the risk ofdysarthria postoperatively. Sev-
eral studies have shown a permanent speech and swal-
lowing impairment in approximately 5 percent of pa-
tients following surgery (12,32,36). Recurrence of
torticollis several months postoperatively is relatively
common. The ideal target is not clear. In Cooper's series,
bilateral lesions were placed in the medial side of the
ventrolateral thalamus (12); Mundinger and coworkers
have advocated a lesion in the zona incerta, just beneath
the thalamus (36); and Bertrand, Molina—Negro, and
Martinez prefer a point in the ventrolateral thalamus
adjacent to the internal capsule (39).
Choreoathetosis
Athetosis is characterized by slow, repetitive writhing
movements, whereas choreic movements are sudden, ir-
regular, and relatively rapid. This complex of symptoms
is most commonly seen in patients with cerebral palsy.
These patients generally suffer from other types of move-
ment disorders as well, including dystonia. ataxia, and
spasticity. Surgery for the symptoms of cerebral palsy
has included ventrolateral thalamotomy (for dystonic
and choreoathetotic movements), lesions of the dentate
nucleus of the cerebellum (for choreoathetotic move-
ments), chronic electrical stimulation of the anterior cer-
ebellum or cervical cord (for spasticity), and lumbar sec-
tioning of nerves (for spasticity).
The results of surgery are variable. Because of the wide
variability in the pathology underlying cerebral palsy, it
is difficult to generalize from one patient to another.
Also, because of the severity of the movement disorders
in many of these patients, surgery must often be done
under general anesthesia, thereby relinquishing many of
the physiological guides normally used for accurate place-
ment of lesions. Narabayashi has reported improvement
in choreoathetosis in 78 percent of children with cerebral
palsy who underwent thalamotomy (41). He advocates
placing the lesion relatively anteriorly in the ventrolat-
eral thalamus (VOA—VOP) or just below the thalamus in
the field of Forel. In another series, Mundinger and asso-
ciates found that 18 percent of patients with choreoathe-
tosis were markedly improved and 32 percent moder-
ately improved at a late follow—up after thalamotomy
(36). All were at least moderately improved immediately
after surgery.
Broggi and coworkers have followed 33 patients with
cerebral palsy (27 congenital and 6 acquired) for one to
four years following thalamotomy (42). Lesions were
placed in the anterior portion of the ventrolateral thala-

310 / CHAPTER 14
mus (VOA, VOP, and zona incerta) in 32 of the patients
who had tremor and choreoathetosis. In 13 of these pa-
tients who had significant dystonia, a lesion was also
placed in the posterior thalamus (pulvinar medialis).
One patient received only the posterior lesion. All pa-
tients except one improved: 73 percent considerably and
24 percent moderately. Tremor and choreoathetosis
were most improved. Dystonia was less affected, and
spasticity was geneially unaffected. Better results were
observed in younger patients. The results by Broggi and
associates are better than have been repoited in most
other series. They attribute this largely to careful selec-
tion of surgical candidates.
Stereotactic destiuction of a portion of the dentate nu-
cleus of the cerebellum is reported to improve
choreoathetotic movements in approximately one—half
of patients who undergo the procedure (43-45). Fairly
large and usually bilateral lesions are necessary. The ef-
fects of electrical stimulation are unclear; some studies
have shown improvement, but others have not (46,47).
This topic is discussed toward the end of this chapter, as
is sectioning of lumbar nerves for spasticity.
Stereotactic Technique and Considerations
To perform Stereotactic thalamotomy one needs (1) a
Stereotactic frame that provides rigid skull fixation and
accurate (i 1 mm) mechanical direction of an instru-
ment to the defined target, (2) a method by which radio-
logical data are processed to define the target point, (3)
an instiument with which to create the lesion, and (4) a
method to confirm the position of the Stereotactic inst1u—
ment intraoperatively.
Stereotactic Frames
The Leksell. the Todd—Wells, and the Brown—Robe1ts—
Wells systems are the Stereotactic instiuments most
commonly used in the United States. Other systems in-
clude the Talairach system and the Reiche1t—Mundinger
system. A number of other devices, generally 1nodifica—
tions of these five systems, are used by individual sur-
geons. Most of these systems have recently been 1nodi—
fied for compatibility with computed tomogiaphy (CT),
magnetic resonance imaging (MRI). or both. The major
differences among instruments are in (1) the radio-
graphic methods used for locating the target point, (2)
the corrections for magnification and parallax on the in-
traoperative x—rays, and (3) the mechanism by which the
electrode carrier and the head are moved with respect to
each other.
In the Leksell system, after the target has been local-
ized on the x—1ay films, the electrode carrier (which is on
a movable arc that can be thought of as lying on the
surface of a sphere) is moved with respect to the target so
that the center of the sphere lies at the target. In the
Todd—Wells system, the head is moved with respect to a
fixed arc to bring the target to the center of the sphere.
The center of the sphere lies at the crossing point of the
central ray of the anteroposterior and lateral x—ray
beams. With either ofthese systems, the superimposition
of the target on the center point of the electrode carrier
arc allows the target point to be approached through a
burr hole made at any point on the skull, as the center of
a sphere can be reached by any radius from the center to
its suiface.
The following discussion of Stereotactic technique fo-
cuses on placement of a VIM lesion using intraoperative
plain radio graphs and ventriculography to determine the
lesion coordinates and using physiological confirmation
ofthe final target site. However, many variations of tech-
nique exist. Some ofthese are noted in the following text,
but the full iange of variations in technique is beyond the
scope of this chapter. A number of excellent surveys that
have recently been published provide a more extensive
description of Stereotactic methods (48-50).
Preoperative Preparation
The shape and size of the ventricular system, the de-
gree of cerebral atrophy, and the possible presence of
infarcts should be carefully evaluated with magnetic reso-
nance imaging in all patients. Any clotting or bleeding
disturbances must be detected and evaluated clinically
and with laboratory tests. Any medication that might
contribute to bleeding, such as aspirin, should be
stopped one to two weeks before surgery. The patient
should also be asked specifically about any history of
allergic reactions to iodinated contrast agents or to local
anesthetics. An antihistamine preparation, such as ci1ne—
tidine (300 mg PO) and benadryl (25 mg PO), given at
bedtime and three hours prior to surgery will help pre-
vent allergic reactions. Dexamethasone (20 mg) given
intravenously approximately three hours before surgery
will further minimize allergic reactions. Phenytoin given
orally prior to surgeiy and intravenously on the morning
of surgery in a loading dose will reduce the possibility of
a seizure during ventriculography orpostoperatively. An-
tibiotic prophylaxis, chosen with respect to the bacteria
prevalent in the hospital environment, should be given
one hour before surgeiy and for 24 hours following sur-
geiy.
Thalamotomy is nearly always performed using local
anesthesia, as the patient's ability to note the effects of
electrical stimulation and to display his or her dyskinesia
is extremely helpful not only in confirming the proper
placement of the electrode but also in assessing the effect
of the lesion. Thus, the preoperative medications aim to
help the patient feel comfortable and alert. Hyperten-
sion, arrhythmias, nausea, and vomiting must be pre-

vented: therefore, painful stimuli and reactions to ventri-
culography that could cause these disturbances must be
avoided. To achieve these goals, premedications, includ-
ing an atropine—like drug to prevent bradycardia, benzo—
diazapines and neuroleptic drugs to control anxiety, and
small doses of a narcotic to block painful stimuli, are
routinely given intravenously before the patient reaches
the operating room. The patient's alertness and vital
signs are monitored continuously.
It is also important that the patient can lie comfortably
for the duration of the operation. Most patients tolerate
reasonably well an operative time of approximately one
and one—half to two hours. For this reason, it is impor-
tant to perform the operation as efficiently as possible,
taking into account the need for careful radiological and
physiological determination of the target site. Therefore,
all of the necessary equipment should be assembled and
ready for use before the patient enters the operating
room. The alignment of the x—ray machine with the ster-
eotactic frame should be confirmed with test films. After
the patient enters the operating room, his or her hair is
shaved, and the scalp is prepared with an antiseptic. The
scalp is then infiltrated with a local anesthetic at the
points of attachment of the stereotactic frame, and the
frame is attached.
Determination ofLesion Coordinates
An intraoperative ventriculo gram, CT scans, or a sagit—
tal MRI scan is used to determine the distance between
the anterior and posterior commissures (the AC—PC
line). Other points of reference (such as the foramen of
Monro or the pineal recess) may be used, but the AC—PC
plane seems to provide the most accurate coordinates for
placement of thalamic lesions. This measurement is
compared with a stereotactic atlas referenced to the AC-
PC plane, such as that prepared by Talairach and co-
workers (51) or by Schallenbrand and Bailey (52). The
coordinates for the target nuclear group or tract are cal-
culated. During surgery, electrophysiological testing is
used to check the lesion coordinates and to determine
the exact site for the lesion.
Some surgeons use CT scans to determine the lesion
coordinates and have reported good results (53,54).
Other centers calculate CT— or MRI—generated target
sites and then confirm and adjust these points with intra-
operative ventriculography (48). CT and MRI scans al-
low the intemal capsule to be visualized, and this infor-
mation can assist in determining the target site. Because
scans are cornputer—generated images, they can be recon-
figured in various planes; also, overlays from a corn-
puter—resident stereotactic atlas can be used to quickly
calculate the lesion coordinates (55).
CT—derived coordinates have been compared with
those calculated from ventriculography, with mixed re-
MOVEMENT DISORDERS / 311
sults. Coordinates from slices 1.5 mm in thickness corre-
lated fairly well with the coordinates derived from ven-
triculography in one study, which found a correlation of
i0.67 mm for the x and y coordinates and i2 mm for
the z coordinate (56). In another study. Birg and Mun-
dinger reported that CT—derived coordinates were accu-
rate to within 10.6 mm of the final targets determined
physiologically (57). In yet another study, however, up to
8 mm discordance in the three—dimensional distance be-
tween the point determined by CT and the point deter-
mined by ventriculography was observed (58). Although
the coordinates derived from ventriculography are gener-
ally thought to be more accurate, this is not altogether
clear. Some investigators believe that introduction of the
contrast material may distort the ventricle and nearby
anatomical relationships, and they note that ventricu-
lography itself adds to the risk and overall morbidity of
the procedure (54,55).
Magnetic resonance imaging may be the imaging
method by which functional neurosurgery is performed
in the future. MRI defines the commissures, thalamic
nuclei, and individual variations in anatomy better than
any method in current use. However, at present there is
some concern that anatomical structures may not be dis-
played in a linear manner but may be subject to some
distortion by the magnetic field (54). The ideal imaging
and surgical method would allow intraoperative visual-
ization of the thalamic nuclei. A computer would then
create three—dimensional reconstructions based on these
radiological data and would plot the ideal lesion point
and the best trajectory to approach that point based on
the individual patient's data, brain—atlas data, and a da-
tabase from other thalamotomy patients.
At the present time, most centers determine the lesion
coordinates using ventriculography and physiological
confirmation (27,59). For determination of the initial
coordinates, intraoperative anteroposterior and lateral
x—rays are taken with the patient's head in the frame. The
approximate position of the target point in the individ-
ual patient's brain can at this point be determined to
within 5 to 10 mm by using an overlay of the outline of
the floor of the anterior fossa, sella, and middle fossa; the
outline also shows the position of the third and lateral
ventricles and the anterior and posterior commissures.
This overlay mask is constructed from ventriculograms
made at the same tube—patient—film distances. With a
Todd—Wells type of frame, an initial adjustment of the
position of the head within the device is made to bring
the target point, determined from the outline mask, to
the center of the electrode arc.
There are two stereotactic approaches to the ventro—
lateral thalamus: one frontal, through a burr hole placed
1 to 2 cm in front of the coronal suture, and the other
parietooccipital, through a posteriorly placed burr hole.
Laitinen surveyed 16 neurosurgeons about their pre-
ferred approach for the placement of a thalamic lesion.

312 CHAPTER 14
He found that 15 preferred the frontal approach,
whereas only one preferred the parietooccipital ap-
proach (60). The frontal approach places the lesion—mal<—
ing electrode along the long axis of VIM and creates a
favorable situation for making a radiofrequency lesion
conforming to the shape of the nucleus. In addition, the
lateral ventricle is most easily and safely cannulated for
ventriculography through the frontal approach. Patients
are most safely operated on in the supine position in
terms of cardiovascular stability and comfort, and the
design of the commonly used stereotactic instruments
makes a frontal trajectory easier to achieve than a poste-
rior trajectory when the patient is supine. The posterior
trajectory has the advantage of allowing an exploring ini-
croelectrode to pass through the ventralis caudalis (Vci—
Vce) sensory relay nucleus prior to entering VIM and to
record thumb, index finger, and buccal commissure neu-
rons, which will confirm the correctness of the lateral
coordinate for the target neurons in VIM (61).
For a frontal approach, the site for the burr hole is
approximately 12 cm posterior to the nasion and 2.5 cm
from the rnidline. The scalp over the burr hole site is
anesthetized, the burr hole made, the dura opened, the
crown of a gyrus cauterized lightly, and the ventricle can-
nulated. Ventriculography is then performed in order to
visualize the outline of the third ventricle and the ante-
rior and posterior commissures. At present, nonionic io-
dinated water—soluble contrast medium, nearly isotonic
with cerebrospinal fluid, is generally used, in a volume of
5 cc injected at a rate of 1 cc per second. Anteroposterior
and lateral radiographs are taken immediately after the
injection is completed.
A line is drawn on the ventriculogram between the
anterior and posterior commissures (Fig. 3), and the tar-
get point is calculated with reference to the coordinates
given in a stereotactic atlas. A system ofCartesian coordi-
nates is used in the atlas to designate the position of
various structures in relation to the AC—PC line. In rela-
tion to a 25 to 26 mm AC—PC line, a lesion in the VIM
nucleus lies approximately 5 mm posterior to the rnid—
point of the AC—PC line, 1 mm above the line, and 13
mm lateral to the middle of the third ventricle (27t62).
These coordinates assume that a frontal trajectory'will
be used for the electrode insertion. The zero point for the
coordinate system is the midpoint of the AC—PC line.
Various methods have been devised for correcting co-
ordinates to compensate for variations in the size of the
thalamus. The simplest technique is to apply a propor-
tionate correction based upon the ratio of the AC—PC
line in the patient to the coordinates given in an atlas.
The actual site of the lesion may vary several millimeters
from the initial target coordinates, depending upon the
physiological testing.
Once the coordinates are calculated, the head is
moved again to bring the target point to the center of the
electrode arc. A third set of anteroposterior and lateral
x—rays is taken to confirm the position.
Physiological Conﬁrmation
Because of the variation in the size and shape of the
thalamus in individual patients, the coordinates derived
from the atlas, even though they have been adjusted with
FIG. 3. (A) Lateral positive contrast ventriculogram showing the outline of the third ventricle and the
anterior and posterior commissures. (B) Tracing of A on which the intercommissural (AC—PC) line and the
target point in VIM are constructed. The long axis ofVlM and the electrode trajectory are also indicated.
(From reference 27, with permission.)

reference to the length of the patient's AC—PC line, must
be further refined by physiological testing. Kelly, Der-
ome, and Guiot determined that the anterior border of
the Vci and Vce, as determined from stereotactic atlases,
varied as much as 6 mm in location when determined
electrophysiologically (63). They found that it was 1reces—
sary to move the lesioning probe from the radiographi—
cally determined point to a new site in 71 of 100 patients.
Most ofthese adjustments required moving the electrode
more laterally.
The electrode is slowly advanced to the preselected
coordinates, and the placement of the electrode is evalu-
ated by noting the patient's response to stimuli adminis-
tered through the electrode or by stimulating the patient
tactilely and recording the response, or by using both
methods. The most valuable confirmatory sign is the pa-
tient's reporting, in response to stimulus, ofparesthesias
in the contralateral thumb and index finger and in the
comer of the mouth. The target lies immediately a1rte—
rior to the sensory relay cells in the ventralis caudalis
(Vce—Vci) for these areas of the hand and face (8). Kelly
and associates found, in a study of 97 patients, that when
the lesion was made in the area ofthe somatic representa-
tion of the thumb, buccal commissure, and index ﬁnger
in the thalamus, complete abolition of the tremor oc-
curred (63).
The stimulus intensity required to evoke the sensory
responses can also indicate whether the electrode is at the
target site or is posterior or anterior to it. With a 2. l—mm
diameter electrode as the negative pole and the positive
electrode on the cut edge of the scalp, and with square-
wave pulses of l—ms duration at 20 Hz, paresthesis
should be produced at an intensity of 3 to 4 volts if the
electrode is in the VIM nucleus. A lower threshold sug-
gests that the electrode is in the VC; a higher threshold
suggests that the electrode is anterior, lateral, or medial
to the VIM. Low—frequency electrical stimulation at the
target site in the VIM frequently accentuates the pa-
tient's tremor, whereas high—frequency stimulation will
abolish it (48).
VIM localization can also be confirmed by using a
microelectrode to record the tremor—linked discharges of
VIM neurons and discharges in response to such kines—
thetic stimuli as muscle stretch. VC neurons can be iden-
tified by recording their discharge to stimulation of the
hand and face (2,62). After the recording, the n1icroelec—
trode is replaced with the lesion—maki1rg electrode. This
technique can make localization more precise, but it also
prolongs the procedure, which in some cases is not desir-
able.
Generation ofLesion
A radiofrequency lesion whose size and rate of devel-
opmerrt are controlled by monitoring the temperature at
MOVEMENT DISORDERS / 313
the electrode tip is the method most commonly used by
stereotactic surgeons in the United States. The size of the
lesion depends on the diameter of the electrode, the
length of the uninsulated tip, and the temperature mea-
sured at the electrode tip (64,65). The lesion has the
shape of an oblate spheroid, or a football. A radiofre-
quency lesion made in VIM with a 2.l—mm diameter
electrode having a 5—mm bare tip and a tip temperature—"
maintained at 75° for 60 seconds will generally produce
excellent control of tremor with minimal side effects.
Lesions can also be made between smaller diameter elec-
trodes positioned several millimeters apart. The leuko-
tome can make a unidirectional lesion, but it is more
likely to cause a hemorrhage. Cryogenic lesions require
insertion of a probe several times larger in diameter than
an electrode, and, unless the probe size can be reduced,
widespread readoption of this technique is unlikely.
When the lesion is made, the patient is asked to hold
up the contralateral arm and to open and close the hand
in a fist to test for the possible occurrence of weakness.
The patient is then tested for the presence of residual
tremor; if necessary, the lesion is then enlarged or addi-
tional lesiorrs are made in adjacent tissue.
Complications and Postoperative Care
Surgical complications occur in l to 2 percent of pa-
tients. The most common complications are infection,
seizures, or subdural hematoma. Subdural hematoma is
more likely in patients with considerable cortical atro-
phy. Cortical atrophy can also lead to an accumulation
of air in the subdural space over the cerebral hemi-
spheres during surgery, which can produce postoperative
fever and confusion. Speciﬁc neurological deﬁcits re-
lated to the size of the lesion and the accuracy of its
placement can also occur. Paresthesias and diminished
sensation in the contralateral face, index finger, and
thumb can occur after a VIM lesion because of extension
of the lesion into the Vci—Vce complex, which lies imme-
diately posterior to the VIM. Contralateral hemiparesis
can occur owing to extension of the lesion laterally into
the corticospinal tract of the posterior limb of the i1rter—
nal capsule, which lies immediately lateral to the VIM
nucleus. Lesions located too inferiorly risk causing he-
miballismus, and lesions too medial, especially if they
are bilateral, can be associated with memory distur-
bances. Language deficit can occur with a unilateral left
thalamic lesion. The mechanism of this deﬁcit is not
completely understood.
Bilateral lesions are more likely to produce a speech
deficit than are unilateral lesions. Bilateral thalamic le-
sions can markedly decrease voice volume, a pseudobul—
bar type of deﬁcit that has been reported to occur in
approximately 30 percent of patients with bilateral le-
sions. For this reason, the benefits and risks of bilateral

314 CHAPTER 14
lesions must be weighed especially carefully in the indi-
vidual patient. If a lesion contralateral to the first lesion
is desired, a period of approximately six months should
generally be allowed to pass before the second operation
in order to assess the effects of the initial lesion properly.
Following surgery, the patient should be observed in
an intensive care unit for one to two days. Most patients
exhibit a mild contralateral central facial weakness for
several days and may exhibit mild hypotonia and ataxia
in the contralateral limbs. There may be a tendency to
neglect the left hand for several weeks after right thala-
mic lesioning. It is important to explain to the patient
that, although the tremor may be completely abolished,
it will usually take a few weeks to several months to re-
leam to use the hand for skilled activities if the tremor
had previously rendered the hand nonfunctional.
Anticonvulsant medication is discontinued at the
time ofdischarge from the hospital. The requirement for
antiparkinsonism medication for rigidity or bradykine—
sia may be reduced in some patients.
OTHER PROCEDURES
Nerve—Sectioning Procedures
Sectioning of nerves is done primarily for torticollis,
although it has also been used to relieve spasticity in
persons with cerebral palsy. Because torticollis, unlike
the other movement disorders, is confined specifically to
one area of the body (the head and neck), selective sec-
tioning of the anterior roots of the cervical nerves (and
sometimes the spinal accessory) can be used to denervate
partially the head and neck muscles involved, thereby
relaxing the muscles and allowing the head to return to a
more normal position. The primary side effect is a loss of
tone in the neck musculature if extensive bilateral dener-
vation is performed. This can result in some difficulty in
holding the head erect and in swallowing.
The initial step in treating torticollis by denervation of
the involved muscles is to characterize the patient's head
and neck movement and the muscular contractions
causing it. It is important to identify the direction and
degree of rotation, ﬂexion, extension, and lateral tilt of
the head. Electromyography is used to analyze the pat-
tern of muscle contraction. A common pattern in torti-
collis is to find contraction of one stemocleidomastoid
muscle and the contralateral splenius capitus, with vary-
ing degrees of contraction of the contralateral levator
scapulae and trapezius muscles (66). Nerve blocks with
local anesthetic can be used to identify nerve roots of the
muscles involved in producing the torticollis. The spinal
accessory nerve can be blocked either before it enters the
stemocleidomastoid or lower in the neck, before it enters
the trapezius. The posterior rami of the anterior roots of
the upper cervical nerves can be blocked as they exit the
intervertebral foramina.
The primary surgical decision to be made is whether to
offer the patient a myotomy or a nerve—sectioning proce-
dure as the initial operation. Myotomy has the benefits
of low risk and a short hospital stay, but it is most success-
ful in comparatively mild cases. The primary muscles
sectioned are the sternocleidomastoid and the contralat-
eral splenius capitus (66). The levator scapulae and the
upper portion of the trapezius can also be sectioned. My-
otomy usually produces about a 50 percent improve-
ment in the resting position of the head. Improvement
generally occurs over one to three months. Physical ther-
apy is important to achieve and to maintain the improve—\
ment.
Sectioning the nerves to the involved muscles is gener-
ally more effective than myotomy. Nerve—sectioning
procedures for torticollis can be divided into two types:
(1) extraspinal section of the dorsal rami of the anterior
roots (39), and (2) intraspinal sectioning of the anterior
roots, which can be combined with intraspinal section-
ing of the spinal accessory nerve (40). Extraspinal sec-
tioning of the dorsal rami is advantageous because it
does not require that the dura be opened and does not
denervate the anterior neck musculature. The dorsal
rami can be sectioned down to the C7 vertebra. Bertrand
and associates reported on 35 patients with spasmotic
torticollis who were treated with selective denervation.
In most instances, the posterior rami of C1 to C4 were
done on one side and the posterior rami of C1 to C5 on
the other. Depending on the individual patient, the spi-
nal accessory was sometimes also sectioned. In this se-
ries, 34 percent had an excellent result, 54 percent a good
result, 9 percent a fair result, and 1 percent a poor re-
sult (39).
Intraspinal sectioning of the anterior roots and the spi-
nal accessory nerve can be performed with low morbid-
ity using microsurgical techniques. The three major de-
cisions to be made are (1) how many anterior roots to
section, (2) whether to do a unilateral or bilateral proce-
dure, and (3) whether to section the spinal accessory
nerve. Sectioning of C4 will result in paralysis of the ipsi—
lateral diaphragm, and bilateral sectioning of the C1 to
C3 roots can result in difficulty holding the head erect
and swallowing (40). For these reasons, a combined tech-
nique consisting of rhizotomies of the anterior roots of
C1 to C3 (to denervate the posterior cervical muscles on
the side of the head rotation and tilt) and of contralateral
stemocleidomastoid muscle myotomy has been advo-
cated (27). Fixed head and neck deviation can be re-
turned to about 10° to 20° from the midline in many
patients by this approach.
A lumbar nerve—sectioning procedure may be useful in
reducing spasticity in patients with cerebral palsy. Pea-
cock, Arens, and Berman performed selective posterior
rhizotomies on 60 children with cerebral palsy (67). The

procedure involves stimulating the rootlets of the poste-
rior L2 to S1 nerves and sectioning the rootlets that dem-
onstrate an abnormal motor response. Patients were fol-
lowed one to five years postoperatively. All patients
except one improved following surgery. Children whose
primary disability was spasticity of the lower extremity
improved most, and those with severe athetosis or
marked contractures improved least. When surgery was
combined with intensive physical and occupational post-
operative therapy, functional improvement was dra-
matic in some instances.
Chronic Electrical Stimulation
The results of chronic electrical stimulation for the
treatment of movement disorders have been inconsis-
tent. In one study, chronic electrical stimulation of the
upper cervical spinal cord produced relief from torticol—
lis in approximately one—third of patients (68); but in
another study it was ineffective for the torticollis, al-
though it ameliorated the cervical pain that may accom-
pany torticollis (5). Cooper and associates reported on 50
patients in whom they inserted electrodes bilaterally
over the anterior cerebellar lobes for the treatment of
cerebral palsy (69). Patients were rated in eight func-
tional areas preoperatively and one and five months
after the initiation of cerebellar stimulation. Stimulation
parameters varied somewhat among patients, but a com-
monly used protocol was stimulation at 10 volts, 200
cycles per minute, administered at eight—minute inter-
vals. These researchers noted improvement in spasticity
as well as in athetosis, speech, and functional status. In a
slightly later report, however, Cooper's group noted that
the overall improvement appeared to be less than ini-
tially observed (70). Penn and associates performed two
studies—a prospective study and a double—blind study—
of cerebellar stimulation for cerebral palsy (71). In the
prospective study, they found that 11 of the 14 patients
(79 percent) were better functionally after 1 to 44
months of stimulation. However, in the double—blind
study, no significant changes in motor function could be
observed.
Waltz, Reynolds, and Riklan designed a four—elec—
trode system that they implanted epidurally over the up-
per cervical spinal cord (C2 to C4) in patients with
various movement disorders. In a series of 160 patients,
improvement of some degree was noted in 84 percent of
the 75 patients with cerebral palsy, 67 percent of the 42
patients with dystonia, 62 percent of the 21 patients with
torticollis, and 73 percent of the 22 patients with post-
traumatic neurologic loss (72). In patients with cerebral
palsy, spasticity was decreased both objectively and sub-
jectively in 94 percent; athetosis was improved in 67 per-
cent of the patients; and posture and balance improved
in 83 percent. These results are considerably better than
MOVEMENT DISORDERS / 315
those reported earlier by Waltz and Pani when a conven-
tional two—electrode system was used (73). Groen and
associates have reported an excellent result in the treat-
ment of a patient with severe myoclonic dystonia by us-
ing chronic stimulation with epidural electrodes irn—
planted over the upper cervical cord (74).
The mechanism for the improvement noted in some
studies following chronic electrical stimulation is not un-
derstood, and the results have been inconsistent. For
these reasons, few patients are now being treated with
these methods.
Neurotransmitter Augmentation
Pumps
Relatively little research has been done into the possi-
bility of delivering neurotransmitters or medications for
the treatment of movement disorders directly into the
cerebrospinal fluid or even into the parenchyma of the
brain. Such systems have been used, however, with
mixed results, to deliver analgesics for chronic pain, ined-
ications such as methotrexate for central nervous system
neoplasms, and cholinergic drugs for Alzheimer's dis-
ease. The potential advantages ofintrathecal drug admin-
istration include bypassing the problems of systemic side
effects, peripheral drug inactivation, poor drug absorp-
tion, serurn protein binding, inadequate blood—brain
penetration, and poor patient compliance. In parkinson—
ian patients, inconsistent delivery of levodopa or other
dopaminergic drugs to the striatum may account for the
"on—off" response; a continuous pump infusion might
alleviate this problem. At the present time, however, in-
trathecal drug administration has largely been ineffec-
tive in the treatment of Parkinson's disease, primarily
because of the development oftoxicity or severe psychiat-
ric disturbances (75). However, success with intrathecal
administration of baclofen for the treatment of spasticity
has been reported. Ochs and associates followed the
progress of 28 patients with severe, intractable spasticity
for up to two years who were treated by chronic intrathe-
cal administration of baclofen using a programmable
drug—administration device. Infusion of 50 to 800 mg per
day of baclofen abolished spasticity with few complica-
tions or side effects (76).
T ransplantalion
The transplantation of dopaminergic adrenal medul-
lary tissue into the basal ganglia of patients with intract-
able Parkinson's disease has produced inconclusive re-
sults (77-79). A recent survey of worldwide experience
in 138 patients indicated that 52 percent were at least
moderately better more than three months after the adre-
nal implant (80). At the present time it appears that

316 / CHAPTER 14
younger patients respond better and with fewer cornpli—
cations than older patients. The most consistent im-
provement in motor performance has been an arneliora—
tion of gait difficulty and postural instability;
antiparkinsonian medications can be reduced in some
patients. The mechanism for this modest improvement
is not known. Although it was first proposed that the
grafts would provide a source of dopamine, there is
currently little evidence to suggest that the implants re-
lease dopamine. Pathological study of three brains ofpa—
tierrts who died from unrelated causes following tra1rs—
plantation showed no evidence of surviving adrenal
medullary tissue (79,8 1,82).
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CHAPTER 15
The Epilepsies
Princi les 0fNeur0surgery,
edite by Robert G. Grossman. Rosenber © 1991.
Published by Raven Press, Ltd., New Yor .
Jerome Engel, Jr., Michel Levesque, Paul H. Crandall, D. Alan Shewmon,
Rebecca Rausch, and William Sutherling
Need for Surgical Treatment, 320
Etiology and Pathology, 320
Natural History, 321
OutpatientEvaluation,322
Basic Evaluation, 322
EEG Evaluation, 323
Imaging Studies, 324
Neuropsychological Testing, 326
Indications for Further Evaluation, 326
Inpatient Evaluation, 328
Phase I (Extracranial EEG Telemetry), 329
Phase 2 (Intracranial EEG Telemetry), 334
The modern era of surgical treatment for epilepsy began
over one hundred years ago with the classic paper of
Horsley (1), but until recently very few patients with
medically intractable epileptic seizures were candidates
for this therapeutic intervention. The past decade has
witnessed a virtual explosion of interest in epilepsy sur-
gery. This is a result of the tremendous advances in neu-
rological diagnostic technology that have vastly im-
proved the localization of structural and functional
J. Engel, Jr: Departments of Neurology, Anatomy and Cell
Biology, and the Brain Research Institute, University ofCalifor-
nia, Reed Neurological Research Center, Los Angeles, Califor-
nia 90024-1769.
M. Levesque: Department of Surgery (Division of Neurosur-
gery), University ofCalifo1nia, Los Angeles, California 90024-
6901
P. H. Crandall: Departments of Neurology, Surgery (Divi-
sion of Neurosurgery), and the Brain Research Institute, Uni-
versity of California, Ios Angeles, Califoinia 90024-6901.
D. A. Shewmon: Departments of Neurology and Pediatiics,
University of Califoinia, Los Angeles, Califoinia 90024-1752.
R. Rausch: Department of Psychiatry and Biobehavioral
Sciences, University of California, Reed Neurological Re-
search Center, Los Angeles, California 90024-1769.
W. Sutherling: Department ofNeurology, University ofCali-
fornia, Reed Neurological Research Center, Los Angeles, Cali-
fornia 90024-1769.
319
Operative Procedures, 341
Electrocorticography, 341
Operative Techniques, 342
Special Considerations for the Developing Brain, 345
Intractability, 345
Timing of Surgery, 346
Identification of the Epileptogenic Zone, 346
Outcome, 347
Complications, 347
Seizures, 348
Psychosocial Adaptation, 350
Research Opportunities, 351
References, 353
abnormalities in the human brain, and of the greater
safety and efficacy of modern diagnostic and therapeutic
surgical procedures. Despite this, however, only a small
fraction of patients who might be candidates for epilepsy
surgery receive attention at epilepsy surgery centers. Al-
though it has been estimated that perhaps as many as
one quarter of a million people in the United States
alone might benefit from surgical intervention, perhaps
only four or five hundred a year receive this treatment
(2). This can be attributed in part to a lag in the dissemi-
nation of information to primary care physicians and
their patients concerning these new developments and
the indications for referral to epilepsy surgery centers,
and in part to the limited number of epilepsy surgery
facilities currently available. The latter results from a re-
luctance on the part of medical centers to commit the
personnel, space, and resources necessary for a dedicated
epilepsy surgery program at a time when reimbursement
for medical care involving expensive diagnostic and ther-
apeutic procedures is being questioned and reduced.
This chapter is intended to address the first problem di-
rectly, by describing the modern role of surgical inter-
vention in the treatment of epilepsy, with the hope that a
subsequent increased demand for epilepsy surgery will
indirectly help to resolve the second problem. The dis-
cussion is primarily concerned with localized resective

320 / CHAPTER 15
surgery for medically intractable partial epilepsy, but an
increasing number of patients with secondary general-
ized epilepsies are becoming candidates for large rnulti—
lobar resections as well as corpus callosurn section, and
these procedures will also be brieﬂy considered.
NEED FOR SURGICAL TREATMENT
The epilepsies afﬂict at least one million people in the
United States. These relatively common neurologic dis-
orders principally affect the lives of young people: over
75 percent of all epilepsy begins before the age of 15 (3).
According to the classiﬁcations of the International
League Against Epilepsy (4), epileptic seizures can be
divided into two categories: generalized seizures (those
that are generalized from the start and are associated
with bilaterally synchronous EEG changes), and partial
seizures (those in which ictal behavior and/or EEG alter-
ations indicate initial involvement of a restricted system
of neurons limited to a single hemisphere). Partial sei-
zures are further divided into simple (no impairment of
consciousness) and complex (impairment of conscious-
ness) subtypes.
In a 33—year—long study of 1,457 patients (5), a fairly
homogeneous white population in the northern United
States with recurrent seizures (either febrile or afebrile)
was identified, showing a mean annual incidence of
48.7/ 100,000 population. Prevalence for recurrent afe-
brile convulsions was approximately 6.7/ 1,000 popula-
tion. Sixty percent of the patients studied manifested
partial seizures, with higher incidence rates at the ex-
tremes of life.
In a French population of a more heterogeneous na-
ture, nearly 40 percent of 6,562 epileptics experienced
complex partial seizures (6). Complex partial seizures
are believed to be the single most common seizure type.
Anticonvulsant therapy is effective in only an estimated
35 to 50 percent of these patients (7). However, inedi-
cally intractable partial seizures—and, in particular,
complex partial seizures—can often be successfully
treated with surgery. Furthermore, surgical intervention
may also benefit carefully selected patients with inedi-
cally intractable generalized seizures that occur as syrnp-
toms of rnultifocal or diffuse cerebral disease processes.
More than 60 years after Horsley ﬁrst described surgi-
cal therapy for partial epilepsy (1), the safety and efficacy
of surgical treatment was unequivocally demonstrated
for those patients in whom interictal EEG paroxysms
were highly unilateral and localized (8-10). Unfortu-
nately, the vast majority of patients were excluded be-
cause they were shown to have bilateral independent dis-
charges or widespread interictal abnormalities.
Regarding the application of surgical treatment in 1967,
Falconer wrote: "the selection ofpatients has been rigor-
ous, and we estimate that only about one in nine persons
referred for surgery fulﬁll [our] criteria" (11). The exces-
sive use of operating room time for intraoperative diag-
nostic studies, and the necessity for an integrated special-
ist team, resulted in surgical treatment becoming
underutilized in the 1960s, and only a handful of centers
treated signiﬁcant numbers of patients.
Since the 1960s, a variety of diagnostic methods have
been developed that further enhance reliable localization
of epileptic foci (12). Our tools have been stereotactic
surgery (13,14), intracranial electrodes which provide for
artifact—free recordings during ictus (15-19), long—term
EEG monitoring (20-22), and techniques to localize ce-
rebral areas demonstrating focal functional deficit
(12,23). The principle objectives in this chapter are to
describe these diagnostic techniques, the surgical opera-
tions, and the results. Introduction of these new diagnos-
tic tests has resulted in identification of a progressively
larger population of patients with partial seizures who
could signiﬁcantly benefit from surgical treatment with-
out incurring undue risks. In contrast to Falconer's expe-
rience, approximately 80 percent of patients evaluated
for surgery at UCLA eventually undergo a therapeutic
procedure. There is, therefore, an increasing need for
more facilities to provide this form of surgical therapy.
ETIOLOGY AND PATHOLOGY
-A distinction must be made between three terms that
are commonly used in reference to partial epilepsy: epi-
leplic focus, epileptogenic lesion, and epileptogenic re-
gion (24). An epileptic focus is an electrographic concept
that refers to the site of maximal EEG-recorded interictal
spike activity. An epileptogenic lesion is a structural con-
cept that refers to a discrete pathological substrate ofpar-
tial epilepsy. An epileptogenic region is a theoretical con-
cept that refers to the area of cerebral tissue that is
necessary and sufficient to generate recurrent partial sei-
zures. It is the epileptogenic region that needs to be iden-
tified by presurgical evaluation procedures and, ulti-
mately, resected in the surgical treatment of epilepsy.
The boundaries of the epileptogenic region, however,
can only be inferred from a variety of tests that define the
location and extent of functional and structural cerebral
abnormalities. The epileptic focus, epileptogenic lesion,
and epileptogenic region are not necessarily congruent
since interictal spikes may be secondarily generated
from multiple brain areas, and habitual seizures may
originate at a distance from documented structural le-
sions. Whereas EEG studies are essential to demonstrate
sites of interictal spike occurrence and ictal onset, these
data do not prove the location of the epileptogenic re-
gion. The pathological substrates of partial epilepsy may
be identified with structural imaging tests such as x-ray
computed tomography (XCT) and magnetic resonance
imaging (MRI), but the underlying defects are more of-
ten demonstrated in the surgical patient population only
by careful histological analysis of resected brain tissue.
These latter studies have helped to develop an under-
standing of the causes of human partial epilepsy (25,26).

Any localized injury to the cerebral cortex occurring
in utero or after birth can give rise to a partial seizure
disorder. Consequently, patients may have a history of
gestational or birth difficulties, head trauma, meningitis,
or other potential cerebral insults. More information
about the pathological anatomy underlying complex
partial seizures has been gained as a result of the tech-
nique of en bloc resection of the anterior temporal lobe
(see "Operative Procedures") (1l,27—29), which allows
careful histologic evaluation of intact surgical speci-
mens. Most lesions encountered are in the medial tem-
poral structures (hippocampal pes, parahippocampal
gyrus, and amygdala), and their nature is usually not
suspected from routine diagnostic evaluation. Mesial
temporal sclerosis, the most common lesion found post-
mortem in patients with complex partial seizures (30), is
also the most common lesion found in resected temporal
lobe specimens (25,26,3l—33).
Controversy exists concerning whether mesial tem-
poral sclerosis is a cause or an effect of recurrent epileptic
seizures. Patients with mesial temporal sclerosis have a
greater—than—expected incidence of prolonged febrile
convulsions in infancy and family history of epilepsy
(31), and prolonged seizures in animals can produce
changes in the hippocampus comparable to human me-
sial temporal sclerosis (34). Such observations have sug-
gested that there is a genetic predisposition to seizure
induction of this particular pattern of cell loss in the hip-
pocampus, and also to the subsequent appearance of re-
current complex partial seizures in association with the
lesion. The epileptogenicity of this pathological abnor-
mality has been inferred from the clinical knowledge
that seizures appear to originate within the sclerotic hip-
pocampal tissue (35), and that removal of a portion of
the temporal lobe containing mesial temporal sclerosis
usually results in resolution of the seizure disorder
(32,33). While patients who benefit from surgery occa-
sionally yield brain tissue that appears completely nor-
mal, quantitative cell counts of hippocampal specimens
from such individuals have revealed abnormal neuronal
loss suggesting a mild degree of hippocampal sclerosis
that is not recognized by routine pathological analysis
(36). It is currently believed that such cell loss leads to
axonal sprouting and synaptic reorganization, account-
ing for the development of chronic epileptic neuronal
activity (37-39).
Besides mesial temporal sclerosis and focal scarring
from trauma or infection, other pathologic changes com-
monly noted in surgically resected specimens from pa-
tients with partial epilepsy, who usually give no history
of any predisposing etiologic event, include glial tumors,
meningiomas, heterotopias, angiomas, cysts, and focal
cortical dysplasia (25,40,4l).
A family history of epilepsy is not unusual in patients
with temporal lobe epilepsy (29,42). In contrast to the
family history of epilepsy found in hereditary primary
seizure disorders, where the seizure manifestations are
THE EPILEPSIES / 321
usually similar in all affected family members, the family
history of epilepsy in patients with complex partial sei-
zures is usually quite varied. Other family members may
have had chronic seizure disorders or isolated seizures
secondary to a variety of cerebral insults. This probably
indicates a genetically determined lowered threshold for
seizures, perhaps necessary for the development of un-
complicated partial epilepsy in response to a single focal
lesion.
Many of the diagnostic tests that will be discussed here
were developed under the assumption that epileptogenic
regions develop in, or adjacent to, areas of damaged
brain and should exhibit evidence of localized functional
deficit as well as epileptic excitability. Ifthe site ofepilep—
tic excitability, as measured by EEG—recorded interictal
spike activity and ictal onset, coincides with the site of
focal functional deficit, measured by a variety of tests to
be described later, the incidence ofpathologic changes in
the resected specimen is high and surgical results are ex-
cellent (23,43,44). When partial epilepsy is treated by
resective surgery, careful pathologic evaluation of the
specimen is of clinical importance, as demonstration of a
structural lesion correlates with a good prognosis
(32,33,45). This information can be useful in preparing
the patient, family, and referring physician for the fu-
ture.
Unfortunately, the concept of a single isolated epilep-
togenic abnormality in patients with a medically intract-
able partial seizure disorder may be an oversimpliﬁca—
tion of the problem. Multifocal abnormalities are often
encountered during the diagnostic evaluation, and pa-
tients frequently are only partially relieved of their epilep-
tic symptoms by surgery (46). Clearly a spectrum of epi-
leptic disorders ranges from simple partial seizure
phenomena due to a small well—deﬁned epileptogenic le-
sion, through bilaterally independent and multifocal dis-
orders, to the so—called secondary generalized epilepsies
(47) in which the cerebral disturbances are so diffuse that
seizures appear to be generalized from the start (24). A
definitive determination of where an individual patient
may lie along this continuum can never be obtained
merely from pathologic evaluation of a resected tem-
poral lobe or other cortical specimens removed at sur-
gery. Additional lesions may still exist in the remaining
brain. Consequently, a clear picture has yet to emerge
concerning the pathophysiological basis of partial sei-
zure disorders that may or may not respond to surgical
intervention. Basic research programs at centers engaged
in the surgical treatment of epilepsy provide an impor-
tant opportunity to elucidate these issues, as will be dis-
cussed at the end of this chapter.
NATURAL HISTORY
A natural history of partial epilepsy is valuable as a
gauge against which to measure the efficacy of any thera-
peutic interventions (48). Strictly speaking, we are not

322 / CHAPTER 15
likely to get a true natural history, since all patients now
receive treatment. A series of articles from Oxford,
which followed 100 children with temporal lobe epilepsy
into adulthood, is the nearest approach to a natural his-
tory so far compiled (49,50—52). The subject patients
were taken from a larger unselected population of over
1000 children with seizures of all kinds. The collection of
the series began in 1948 and ceased in 1964. Patients
were followed until 1977. Clinical diagnosis was con-
firmed by two physicians, and an EEG demonstrated a
focal discharge in one or both temporal regions. Collec-
tion was strictly consecutive, and it was possible to trace
all of the patients in the series. Ninety—five patients were
divided into three outcome categories (five patients died
as children before the age of 15). Thirty—three patients
were able to support themselves socially and econorni—
cally, were seizure—free, and were not receiving anticon—
vulsant medication. Thirty—two were also able to support
themselves socially and economically; however, they
were receiving anticonvulsants and were not necessarily
seizure—free. Thirty patients were not able to support
themselves and were considered to be totally dependent.
Eight risk factors were related to an adverse outcome:
(1) an IQ under 90; (2) seizure onset before 2.5 years of
age; (3) five or more severe grand mal attacks; (4) daily
temporal lobe attacks; (5) a left—sided EEG focus; (6) hy-
perkinetic syndrome; (7) catastrophic rage; and (8) the
necessity for special schooling. In the best group, 30 of
the 33 patients had three or fewer risk factors and 10 had
none. In the worst group, 25 of the 30 patients had four
or more risk factors. Nearly all patients in the best group
went into sustained remission before the age of 15; in
retrospect, some (if not most) of these probably had the
familial condition of benign epilepsy, with centrotem—
poral spikes (53), rather than temporal lobe epilepsy.
It is of particular interest here that a subset of patients
in this study who continued to have seizures ultimately
underwent surgical treatment. An investigation from
London of 666 patients with temporal lobe epilepsy (54)
also contained a subset of patients who had medically
intractable seizures and underwent surgical treatment.
Whereas in both studies patients with persistent seizures
generally experienced functional deterioration, this did
not occur when surgical resection successfully abolished
the habitual ictal events. Such evidence that psychoso-
cial. if not physiological, disability can be progressive has
been used as an argument for early surgical intervention
<55.56). These findings indicate the need for skilled re-
view of the medical and social status of children with
complex partial seizures. For those who can reach full
recovery, the withdrawal of drugs before the age of 15 is
of great importance. When seizures continue into adoles-
cence, full investigation with a view to possible neurosur-
gical treatment should be undertaken. Lindsay et al. (49)
concluded that "a major danger in caring for children
with temporal lobe epilepsy is delaying operation for re-
lief of seizures so long into adult life that social recovery
has become impossible."
OUTPATIENT EVALUATION
Because only patients with partial seizures can be con-
sidered candidates for localized surgical resection of an
epileptogenic region, it is important to obtain evidence
of a partial epileptic condition from history, neurologic
examination, and routine laboratory testing before sub-
jecting the patient to more exhaustive evaluation. How-
ever, some patients, usually children, with diffuse unilat-
eral or secondary generalized epileptic disturbances may
be candidates for larger multilobar resections, hemis-
pherectomy, or corpus callosum section.
Basic Evaluation
Description oflctal Behavior
Usually the partial nature of a seizure can be ascer-
tained from a careful description of the behavioral event
given by a reliable observer. Therefore, the initial inter-
view with an epileptic patient should ideally include a
parent, spouse, or some other individual who has wit-
nessed the events in question. Subjective warnings noted
by the patient (auras) are an important indication of a
partial seizure disorder and may be useful in differentiat-
ing between partial and generalized epilepsy. Precise in-
formation regarding auras and initial clinical ictal events
can also have localizing value, although this is not as
reliable as was once believed (57,58).
Partial seizures accompanied by impairment of con-
sciousness (which may consist only of amnesia) are gener-
ally considered indicative of limbic system involvement.
The term complex partial is often used interchangeably
with limbic, psychomotor, or temporal lobe seizures.
However, it is very important to realize that complex
partial seizures can, and often do, result from extratem—
poral epileptogenic regions that invade temporal lobe
limbic structures only secondarily.
Some patients with complex partial seizures do not
experience or remember auras, and an accurate descrip-
tion of the behavioral ictal onset is sometimes unavail-
able or unreliable. Furthermore, partial seizures may not
always have a discrete focal or lateralized behavioral on-
set; ictal events that appear to be generalized at the start
can represent spread from a single epileptogenic region
located in a so—called silent area of the brain. Such sei-
zures include those that are secondarily generalized (par-
tial becoming tonic—clonic) according to the interna-
tional classification (4), as well as complex partial
seizures that begin with an alteration in consciousness
without warning and proceed to simple or complex auto-
rnatisrns involving both sides of the body. These latter
ictal behaviors generally indicate a partial onset, even
though the behavioral manifestations are bilateral from
the start; however, brief events may be difficult to differ-
entiate frorn absences that occur with generalized seizure
disorders (47,59). Consequently, evidence to substan-

tiate the partial nature of an epileptic abnormality must
occasionally depend on EEG and imaging studies.
Patients often give a history of more than one type of
seizure. Most patients with partial seizures also have had
one or more secondarily generalized seizures. As a gen-
eral rule, the more different types of seizures a patient
has, the more likely she or he has rnultifocal or diffuse
cerebral disease and is not a good candidate for resective
surgery. However, careful evaluation of ictal events (as
described in the section on inpatient evaluation) may
reveal that what first appeared to be a variety of seizure
types may actually be a number of manifestations of the
same basic seizure, consistent with a single dominant
epileptogenic region.
Nenrologic Examination
Even though patients with partial seizures who are be-
ing considered for surgical therapy usually do not demon-
strate focal deficits on neurologic examination, a careful
evaluation should always be performed. General physi-
cal findings, such as cafe au lait spots with axillary freck-
ling or evidence of hemiatrophy, may indicate heredi-
tary or congenital disorders associated with focal brain
lesions. The most common neurologic abnormalities
found in patients with complex partial seizures are mem-
ory disturbances, which often are revealed on specialized
testing, even when they have not been elicited by history.
Problems in remembering verbal material and asso-
ciated word—finding difficulties suggest an epileptogenic
region in the language—dominant hemisphere. More spe-
cific motor or sensory neurologic deficits usually imply
that the major pathologic changes are suprasylvian. For-
mal visual field testing is generally included in the
screening test battery, although visual field deficits are
not common in the absence of large mass lesions.
EEG Evaluation
Routine EEG
The most useful diagnostic tool in the evaluation of
the epileptic patient has traditionally been the EEG. For
the potential surgical candidate, routine outpatient EEG
studies are important to confirm the partial nature of the
epileptic disorder by demonstrating focal interictal spike
activity, as well as other focal intermittent or continuous
abnormalities. Preliminary localizing information may
also be obtained from the outpatient interictal EEG, but
differences of opinion exist concerning the relative value
of interictal electrophysiological phenomena for pur-
poses of localization, as compared with recordings of ic-
tal onset (l2,19,60). Although good results can be ob-
tained in many cases with surgery performed entirely on
the basis of interictal scalp EEG localization, there is
general agreement that interictal epileptiform discharges
can be misleading in 10 to 20 percent of patients
(23,6l,62). This is particularly true with complex partial
seizures of limbic origin. Interictal EEG spikes may be
THE EPILEPSIES / 323
more localizing with extratemporal neocortical foci, par-
ticularly if the interictal EEG spikes correspond with a
discrete structural lesion demonstrated on XCT or MRI.
Presently, inpatient ictal recordings are always also ob-
tained on all patients considered for surgery at UCLA
(see "Inpatient Evaluation").
There are a number of potential hazards to under-
stand and avoid when using routine interictal EEG stud-
ies to identify a partial seizure disorder and localize an
epileptogenic lesion. A number of normal EEG variants,
such as small sharp spikes, 14 and 6/sec positive spikes.
wicket spikes, the so—called psychomotor variant and
6/sec (larval or phantom) spike and wave phenomena
can be mistaken for pathologic spikes if their characteris-
tic features are not recognized (47). Abnormal spike dis-
charges, such as occipital spikes, periodic lateralized epi-
leptiform discharges, and sylvian spikes, may not be
associated with epilepsy or may not indicate the location
ofa resectable epileptogenic region (47). Even epilepsy-
related pathologic interictal EEG spikes may tend to
shift location, particularly in children (61), and do not
always correlate reliably with the site of the epileptogenic
region (23,62,63). Bilateral independent temporal EEG
spikes are common in patients with Complex partial sei-
zures who eventually do well with unilateral temporal
lobectomy (23,46), and the predominant EEG focus
may occasionally be contralateral to the primary epilep-
togenic region (23).
Special Electrodes
Basilar electrodes that are capable of recording epilep-
tiform activity originating from mesial aspects of the
temporal lobes are most commonly used in the EEG
evaluation of patients with complex partial seizures.
Electrodes placed on the earlobes, over the zygoma, or in
the true temporal (Tl,T2) location are at least as effective
as nasopharyngeal electrodes in identifying interictal
spikes not seen with the routine 10-20 placement system
(64). Because nasopharyngeal electrodes are unco1nfort—
able, unstable, near pharyngeal muscles that cause arti-
facts that may be impossible to differentiate from cere-
brally generated spikes, and are separated by wet mucous
membrane that makes lateralization difficult, their use is
discouraged. Sphenoidal electrodes provide a somewhat
higher yield than other basilar derivations and are quite
stable, so that their use is recommended for long—ter1n
monitoring (65); however, this yield is not sufficiently
high to warrant their routine use in the outpatient EEG
laboratory. The use of several basilar derivations si1nulta—
neously may aid in defining an electrical field for interic-
tal spikes that has additional localizing value (66).
Small sharp spikes and 14 and 6/sec positive spikes
lack their characteristic appearance when recorded from
mesial temporal placements and cannot be easily differ-
entiated frorn pathologic spike phenomena, even by the
most experienced electroencephalographer, without ac-

324 / CHAPTER 15
cess to EEG patterns simultaneously derived from the
scalp (47). Therefore, basilar EEG studies should always
include an independent lateral temporal montage to
identify the surface electrical field of all medially re-
corded spikes (as in Fig. 4). These recordings should not
be done on an 8—channel EEG machine; such machines
do not allow sufficient independent surface monitoring
to analyze medially recorded phenomena properly. At
least 12, but preferably 16 or more, channels should be
used for these studies. A good general rule is to take seri-
ously only those rnesial temporal spikes that have an
identifiable field over the appropriate temporal surface
not characteristic of 14 and 6/sec positive spikes, small
sharp spikes, or other normal variants. By using these
techniques properly, one can obtain positive recordings
from patients with suspected complex partial seizures
significantly more often than by routine EEG alone
(65,67).
Activation
Activation procedures such as hyperventilation, pho-
tic stimulation, and sleep are routinely used in the EEG
laboratory. Hyperventilation may provoke focal slow-
ing, spikes, and even partial seizures. Since photosensi-
tive epilepsy is almost always a primary generalized dis-
order, photic stimulation is much less likely to be useful
in the evaluation of partial seizures, except in the differ-
ential diagnosis between partial and generalized seizure
disorders. Sleep can also activate interictal EEG spike
discharges, particularly frontotemporal spikes associated
with complex partial seizures, but it is important to ig-
nore the normal and clinically insignificant sharp tran-
sients associated with sleep, and to be aware that interic-
tal EEG spikes activated by slow-wave sleep have less
localizing value than interictal spikes seen during wake-
fulness (68). As with basilar electrode placements, sleep
studies are useful for demonstrating the presence of a
focal epileptiform abnormality when the diagnosis of a
partial seizure disorder is not clear from history and ex-
amination and routine EEGs are equivocal; therefore,
the two techniques are often used together. However, if
the diagnosis is clear from other evidence, and the pa-
tient is scheduled to undergo an inpatient presurgical
evaluation, these procedures are not necessary.
Imaging Studies
Structural Imaging
Focal structural abnormalities may be demonstrated
with XCT or MRI, although this is not as common
among patients referred for surgical treatment of epi-
lepsy as has been reported for partial and secondarily
generalized epilepsies in general (69-75). When a well-
defined mass lesion is found, the surgical treatment is
often dictated more by the nature of this lesion than by
the epileptic seizures. Patients with obvious brain tu-
mors will not be considered further in this discussion of
surgery for epilepsy per se. With the advent of high—res0—
lution structural imaging, however, the clinical impor-
tance of many identified abnormalities is not always
clear. Defects seen on XCT and MRI can come and go
(76,77), and mesial temporal unidentified bright objects
(UBOs) consisting of nonspecific increases in intensity
on T2—weighted MRI image, unassociated with changes
on the Tl—weighted image, may have no structural corre-
late (78). Nonspecific structural defects such as small
cysts, areas of calcification, disgenetic disturbances, and
localized cerebral atrophy that are not in themselves an
indication for surgery help confirm the location of an
epileptogenic region identified by electrographic and
other functional means.
If the site of a demonstrated structural abnormality
correlates with the site of epileptiform EEG activity (see
"lnpatient Evaluation"), this is helpful in localizing re-
sectable epileptogenic tissue; however, one should bear
in mind that structural abnormalities may be totally
unrelated to the epileptogenic area (23). Consequently,
demonstration of a structural abnormality by itself
should not be considered sufficient evidence for localiza-
tion of the source of epileptic seizures.
Functional Imaging
The most important confirmatory test used at UCLA
is positron emission tomography (PET) with 18F—ﬂuoro—
deoxyglucose (FDG) (23,43,44,79—81). Many centers
have now demonstrated that the majority of patients
with partial epilepsy who are candidates for surgical
treatment have FDG—PET scans with characteristic meta-
bolic disturbances (82—85). This consists of a zone of
hypometabolism (Fig. 1), usually including the site of
ictal onset determined by surface and depth electrode
EEG telemetry, and the site of a structural lesion deter-
mined by microscopic evaluation of the resected speci-
men (43,80,8l). Although temporal lobe hypometabo-
lism is encountered in 70 percent or more of patients
with medically refractory complex partial seizures of
mesial temporal origin, they are less commonly seen
when the epileptogenic region is neocortical (86). FDG-
PET may be particularly important in the presurgical
evaluation of infants and small children with severe uni-
lateral or secondary generalized epilepsy (87) where neu-
ronal plasticity allows larger resections than in the adult,
and chronic intracranial EEG recording is difficult to
perform. Many of these patients show unilateral hypo-
rnetabolic zones, even when structural imaging studies
are unremarkable. In this situation, FDG—PET also helps
to confirm that the contralateral hemisphere is function-
ing normally.

lctal FDG—PET scans reveal areas ofhyper— and hypo-
metabolism that correspond to the origin and/or spread
of epileptic discharge during the seizure (82,84,88). Such
ictal scans may be useful for elucidating the anatomic
substrates of speciﬁc ictal behaviors; however, because
regions involved in propagated activity cannot be distin-
guished from the site of seizure origin, these scans are not
as useful as interictal FDG—PET studies for localizing the
primary epileptogenic region.
Studies comparing FDG—PET with various EEG tests
have revealed basic differences (70,89). The FDG tech-
nique measures the average intensity, over time, of meta-
bolic activity in all cellular elements within each cerebral
stmcture scanned. The results are weighted according to
the energy requirements of individual elements without
regard to the specific function or orientation of these
elements, or to the temporal sequence of their activation.
The EEG, on the other hand, is a more dynamic tech-
THE EPILEPSIES 323
FIG. 1 . PEI’ scan with FDG from a patient
with complex partial seizures of left mesial
temporal origin. This scan was performed on
a Siemens—CTl 831 tomograph with an in-
plane resolution of approximately 5 mm. Fif-
teen horizontal planes of section are ob-
tained simultaneously, and one or more sets
of planes can then be reformatted into coro-
nal, sagittal, orotherplanes as desired. Note
that images front this tomograph show the
patients left side on the right and the pa-
tient's right side on the left. The PEI’ scan of
this patient demonstrates mild left temporal
hypometabolism, which can be seen on all
horizontal planes of section through the
temporal lobe shown in (A) and enlarged for
one section in (B). The hypometabolism can
also be appreciated in the coronal section
(C) and in sagittal section through the left
temporal lobe (D) when compared to the sag-
ittal section through the right temporal lobe
(E). (From reference 24, with permission.)
nique inﬂuenced by the spatiotemporal relationships of
specific excitatory and inhibitory neuronal events within
these stmctures. The results are weighted according to
the degree of synchrony of these events and their spatial
orientation, Without regard for the number of elements
actually involved. The FDG—PET technique reveals ana-
tomic localization better than EEG; the EEG is neces-
sary for the temporal sequencing of events. These tests
are complementary and together provide more func-
tional information about the epileptic abnormalities
under study than either test used alone.
Nonepileptogenic lesions can also be seen as a zone of
hypometabolism. Therefore, this FDG—PET defect per se
is not sufficient for identification of an epileptogenic
brain region and should be considered only as confirma-
tion of a focus demonstrated electrophysiologically. Al-
though the transformation of an interictal hypo1netabo—
lic zone into a hypermetabolic zone during ictus may be

326 / CHAPTER 15
pathognomonic of an epileptogenic region without EEG
evidence of epileptogenicity, focal hypermetabolism has
been reported in other conditions (90).
Single photon e1nission—co1nputed tomography
(SPECT) is also being used to confirm the location of
epileptogenic regions. Interictal SPECT with tracers that
nonquantitatively measure cerebral perfusion provide
patterns that are similar to those of interictal FDG—PET
(91-94), although the reduced spatial resolution de-
creases the yield. In addition, a variety of biologically
active tracers does not exist, and radiation exposure to
the patient is greater than with FDG—PET. Ictal SPECT
is, however, more easily performed than ictal FDG—PET,
and can reveal patterns of hyper— and hypoperfusion that
may be useful for identifying the epileptogenic region
(93,95,96). However, as with ictal FDG—PET, it remains
difficult to differentiate the site of ictal origin from areas
of ictal'propagation. SPECT is currently more accessible
than PET since it does not require an on—site cyclotron;
but PET technology is becoming less complicated, and
more reasonably priced clinical systems are now being
made (97). Where PET is not available, SPECT remains
a useful alternative.
Neuropsychological Testing
Neuropsychological testing provides useful diagnostic
and prognostic information and is an important part of
the presurgical evaluation (98). The neuropsychological
evaluation is frequently used in combination with other
functional tests for confirmation of dysfunctional brain
areas (12,23,99). Prognostic uses of the neuropsychologi-
cal evaluation include information as to the probability
of seizure control following a focal resection (100,101),
prediction of the type and degree of cognitive loss follow-
ing surgical intervention (102,103), and the likelihood of
postoperative improvement in psychological and psy-
chosocial function (104,105).
A comprehensive neuropsychological evaluation
should assess a wide range of functions. The evaluation
should include measures of general brain integrity as
well as tests sensitive to dysfunction of the temporal lobe
and extraternporal areas. Psychological domains gener-
ally assessed are language, intelligence, attention, cogni-
tive—tracking, sensation, perception, motor skills, and
memory functioning, as well as personality and psycho-
social function (98,106).
The most reliable neuropsychological index of lateral-
ization of temporal lobe dysfunction is a selective 1ne1n—
ory deﬁcit associated with one temporal lobe (107). The
memory deficit should exist independent of other neuro-
psychological deficiencies. Verbal memory tests such as
the delayed recall of logical prose and delayed recall of
newly learned unrelated word—pairs, both derived from
modified administration of the Wechsler Memory Scale
(108), have been found to be particularly sensitive to
dominant temporal lobe dysfunction. Nonverbal 1ne1n—
ory tests, such as the Rey—Osterrieth draw and recall test
and the delayed recall of the visual—reproduction subtest
of the WMS, are more sensitive to nondominant tern-
poral lobe functions. Interpretation of the neuropsycho-
logical profile is dependent upon knowledge of hemi-
spheric dominance for language, which is determined by
the intracarotid sodium amobarbital procedure (IAP).
This test is described in the section on inpatient evalua-
tron.
Indications for Further Evaluation
Positive Indications
Localized surgical resections are done to treat partial
seizures that appear to have a well—defined site of ictal
onset in a cortical area that can be removed without pro-
ducing additional unacceptable neurological deﬁcits. Al-
though any epileptic disorder characterized by stereo-
typed partial seizures can be considered a positive
indication for further evaluation, in practice most pa-
tients who undergo inpatient evaluation for localized
surgical resections have complex partial seizures. PosiB
live indications for surgical treatments such as corpus
callosum section or large multilobar resection, including
hemispherectomy, are less well defined. Patients with sec-
ondary generalized epilepsies should be considered for
callosotomy when drop attacks are the most disabling
feature of their disorder.
Most complex partial seizures are limbic ictal events
that originate from one mesial temporal region, al-
though they also can occur as a result of epileptogenic
regions elsewhere that project to mesial temporal struc-
tures. The best surgical outcomes are obtained in pa-
tients with cornplex partial seizures of mesial temporal
origin who undergo anterior temporal lobectomy
(9,l0,32,33,45,46,l00,l09—l13). As a group, particu-
larly when the lesion is mesial temporal sclerosis, these
patients have a relatively high incidence of positive fam-
ily history for epilepsy, prolonged febrile convulsions in
infancy, and an onset of seizures in the ﬁrst decade of life
(31). If an aura is present, it often has an epigastric or
other autonomic component, although a wide variety of
hallucinations and cognitive, affective, and psychosen—
sory symptoms may occur, followed by altered con-
sciousness, staring, automatic behavior, and postictal
confusion, with amnesia for the ictal event. Typically
these patients also experience auras without seizures.
Complex partial seizures may become secondarily gener-
alized, but this is a relatively infrequent occurrence.

(Other simple motor or special sensory seizures with pre-
served consciousness generally indicate extraternporal
onset, which is an indication for other types of focal cor-
tical excision). Neurologic examination may reveal a
moderate memory deficit and radiologic studies are
usually normal. The characteristic EEG pattern consists
of unilateral or, more commonly, bilateral independent
anterior temporal interictal spike foci. These features are
typical of "temporal lobe seizures"; however, such fea-
tures do not invariably distinguish an epileptogenic re-
gion within the temporal lobe from a primary site of
seizure generation elsewhere in the limbic system, or in
other cerebral areas that project to limbic structures.
Consequently, patients with such seizures are good can-
didates for presurgical evaluation, but conclusions re-
garding the actual location of the epileptogenic region
should not be made on this information alone.
While this profile characterizes an ideal surgical candi-
date, there is an infinite variety of manifestations of sur-
gically resectable epileptogenic regions. Each patient
presents a unique problem and must be dealt with inde-
pendently. It may be easier, therefore, to describe those
patients with partial epilepsy who, at this stage in the
outpatient work—up, are not candidates for further pre-
surgical evaluation.
Negative Indications
If pharmacologic management has not been adequate
to establish that the patient is medically intractable, sur-
gery is generally not considered until appropriate anti-
convulsants have been given a proper trial (42,55). Sur-
gery should also not be considered in patients with
seizures insufficiently severe to seriously disrupt the qual-
ity of life. Decisions regarding the severity of the seizure
disorder cannot be based on any uniform criteria, but
must take into account each patient's capabilities and
needs. For instance, a patient with a nondemanding oc-
cupation, who works alone with no set schedule, may
tolerate several seizures a day, while another with ern—
ployment involving continued interaction with the pub-
lic or constant attention and quick judgment may be
unable to work withjust a few seizures a year. In general,
patients with fewer than several seizures a month are not
considered for surgical therapy. Patients with severe
mental retardation are relatively poor candidates for lo-
calized resection, since this usually indicates diffuse cere-
bral damage and multifocal epilepsy. However, such sur-
gery may be justified occasionally if a reduction in
seizure frequency would signiﬁcantly ease patient man-
agement at home or in an institution. While lower intel-
lectual scores have been correlated with poorer seizure
control following anterior temporal lobectomy (101),
there is no universal agreement concerning the degree of
mental impairment necessary before a patient should no
longer be considered a candidate for this procedure. Fur-
THE EPILEPSIES / 327
thermore, such patients may benefit from other surgical
interventions such as corpus callosum section or large
multilobar resections; in small children, the latter can
reverse a developmental delay. Chronic psychosis is of-
ten considered a relative contraindication to surgical
therapy, since this condition is rarely reversed when sei-
zures are abolished and patients remain incapacitated
(114). Less severe personality disturbances can improve
with abolition of habitual seizures (114), however, and
should not dissuade a decision to proceed with presurgi-
cal evaluation. When seizures are due to a known pro-
gressive cerebral degenerative process, localized surgical
intervention is usually inappropriate. Finally, patients
with medical contraindications to surgery should not be
considered further.
Common Misconceptions
Many good surgical candidates are never referred for
focal resective surgery as a result of misconceptions con-
cerning the indications for these procedures (12). Sur-
gery should be considered even if medication is shown to
be effective, when the necessary7 dose required to control
seizures also causes unacceptable side—effects. This is a
particularly important concern in children, who do not
complain of overmedication and whose resultant poor
school performance or bad behavior may be erroneously
attributed to the epileptic disorder. Although patients
with progressive degenerative diseases are usually not
considered candidates for localized resection, progres-
sive symptoms may be due to increasing seizure fre-
quency, rnore severe seizures, drug effects, or psychoso-
cial factors, rather than to an underlying irreversible
progressive neuropathological process. Memory deﬁcits
and specific cognitive impairment are not a contraindi—1
cation to focal resective surgery since appropriate resec—l
tion does not necessarily increase these disabilities. In '
fact, memory often improves and IQ increases by an
average of 10 points following successful anterior tern-
poral lobectorny (101). Seizure—related reversible psy-
chotic symptoms, such as transient postical psychosis,
are not the same as chronic psychosis, and usually re-
solve postoperatively when seizures no longer occur.
There is no truth to the old belief that surgery is danger-
ous in the language—dominant hemisphere, since speech
areas now can easily be identified and avoided. Patients
with partial seizures that secondarily generalize, seizures
with multiple spread patterns from a single focus, "type
II" complex partial seizures (115), bilateral independent
or synchronous EEG spikes, and even occasional contra-
lateral ictal EEG onsets, usually have a single epilepto-
genic region that can be identified and resected with ben-
eficial results. Such patients, therefore, should not be
denied surgical consideration. Since patients with mesial
temporal sclerosis often have a family history of epilepsy
(31), this finding should not raise concern about a pri-

28 / CHAPTER 15
inary idiopathic epileptic disorder (116) that is not
treated surgically.
With increasing application of new diagnostic ap-
proaches (12), as well as improved safety of larger surgi-
cal resections and corpus callosum section, particularly
in children, more and more epileptic patients who would
not have been considered surgical candidates a few years
ago are now benefitting from surgical intervention. We
are rapidly reaching a point where ahnost any patient
with medically refractory epileptic seizures who appears
to have a partial or secondary generali/ed epileptic dis-
order deseives at least a preliminary evaluation at an
epilepsy surgery center.
INPATIENT EVALUATION
The approaches to presurgical evaluation are largely
dictated by the intended surgical procedure (2,1 17-1 19).
Figure 2 is a ﬂow chart demonstrating the various proto-
cols for surgical treatment of epilepsy at UCLA. Al-
though this chapter is concerned primarily with localized
resective surgery, evaluation for large inultilobar resec-
tions, hemispherectomy, and corpus callosum section
are also considered brieﬂy. Patients who are candidates
for localized resection undergo an initial phase 1 inpa-
tient evaluation, which includes scalp and sphenoidal
EEC telemetry with video monitoring as well as addi-
tional confirmatory tests that do not require intracranial
procedures. If the epileptogenic region is not adequately
defined, patients may then go on to aphase 2 evaluation
with intracranial EEC telemetry and video monitoring.
If the epileptogenic region is suspected to be in limbic
structures, stereotactic depth electrode placement is
usually performed, often with subdural strips over se-
lected neocortical regions as well. When seizures are sus-
pected to originate in lateral neocortical regions and the
involved hemisphere is known, placement of subdural
grids is preferred. When there is doubt concerning which
intracranial recording procedure is most appropriate,
depth electrodes are used, since a second phase 2 with
subdural grids is always possible. When a craniotomy for
subdural grid placement is done initially, however, the
bone becomes too unstable to permit a second evalua-
tion with the UCLA orthogonal approach to stereotacti-
cally—implanted depth electrodes.
If the intended surgical procedure is a standardized
resection, such as anterior temporal lobectomy (26) or
amygdalohippocainpectoiny ( 120), the presurgical evalu-
FIG. 2. Flow chart illustrating the presurgical
evaluation scheme for epileptic patients at
UCLA. “Identification of extratemporal epilep-
togenic zones in patients who undenNent
depth electrode evaluation may require a sec-
ond chronic intracranial procedure with sub-
dural grid electrodes. **Young children may
also be considered for hemispherectomy.
Also, some patients who do not already have
a severe hemiparesis may wish to undergo
surgery and accept this inevitable handicap.
(From reference 24, with permission.)

ation is designed to determine il" habitual seizures origi-
nate within the brain tissue to be resected, and if this
region also demonstrates focal functional deficits. When
the intended surgical procedure is a tailored resection
(121,122), the presurgical evaluation must not only
identify the site of seizure origin, but also the presumed
extent of the epileptogenic region and often the bound-
aries of adjacent primary cortical areas that cannot be
damaged. This latter situation, therefore, also requires
functional mapping procedures.
There arc several electrophysiological approaches to
the localization of the epileptogenic region in patients
with partial seizures who may be candidates for resective
surgical therapy (12). Some centers rely heavily on non-
invasive interictal EEG recording techniques, using rou-
tine scalp and basilar electrodes. These are usually sup-
plemented by intraoperative electrocorticography
(ECoG) (19,62,63), as described in the section on opera-
tive procedures. Others feel the epileptogenic region is
more reliably localized by inpatient recording of ictal
events using long—term video EEG monitoring (16), ei-
ther with scalp and sphenoidal electrodes (23), or with
intracranial (epi— and/or subdural) (17,18) or stereotacti—
cally implanted depth (13-15) electrodes. There is no
consensus on a single correct electrophysiological ap-
proach to the evaluation of the presurgical candidate
(12). Most now agree that ictal plus interictal data are
preferable to interictal data alone, and that chronic intra-
cranial recording is at least sometimes appropriate. Con-
siderable disagreement remains about when interictal
EEG and ECoG recordings are sufficient, and when
chronic intracranial recordings are necessary (19,123).
Because ofthe potential for false localization from elec-
trophysiological measures of epileptic excitability, it is
very important to use independent measures of func-
tional disturbance to confirm scalp and intracranial
EEG findings, and not to base decisions on only a few
tests. Consequently, the presurgical evaluation in most
centers now involves a variety of tests aimed at identify-
ing areas of abnormal l?rain structure and function (12).
The UCLA presurgical evaluation protocol utilizes ex-
tracranial and, as needed, various intracranial electro-
physiological approaches to localize epileptiform abnor-
malities. In addition, a variety of tests which measure
focal functional deﬁcits are employed to conﬁrm the lo-
cation of the epileptogenic region determined electro-
physiologically. This protocol, therefore, can be used to
illustrate most of the diagnostic procedures currently
available in epilepsy surgery centers.
Phase 1 (Extracranial EEG Telemetry)
Methods 0fScalp and Sphenoidal EEG Telemetry
Patients determined by outpatient studies to be poten-
THE EPILEPSIES / 329
tial surgical candidates are initially admitted for approxi-
mately one to two weeks of scalp and sphenoidal EEG
telemetry with video monitoring. In some patients with
daily seizures, phase 1 EEG telemetry can actually be
achieved on an outpatient basis by recording in ate1e1ne—
try unit located in the EEG laboratory for 8 hours a day.
Sphenoidal electrodes are 50—gauge, Teﬂon—coated, 15-
stranded stainless steel wires, which are bared at the tip.
These electrodes are inserted through a 22—gauge 1.5-
inch needle, as shown in Figure 3 (24). Wires have been
left in place for over six weeks without discomfort or
deterioration in recording characteristics.
During inpatient evaluation, the EEG is recorded con-
tinuously (24 hours a day) according to approved stan-
dards for long—term monitoring (20), transmitted Via ra-
dio or cable telemetry, and stored on videotape (124).
Behavior is recorded by two video cameras and a micro-
phone, and data arc continuously stored on videotape.
Much of the patient's time is spent in quiet activities so
video recordings can be made, but ambulation and exer-
cise are possible without losing the EEG signal. As a rule,
FIG. 3. Illustration to show the placement of sphenoidal elec-
trodes. The needle is inserted approximately 1 inch anterior
to the tragus immediately under the zygomatic arch (black
dot on lateral view). The tip of the electrode should lie close to
the foramen ovale (basilar view). Inset shows how multi-
stranded Teflon—coated wire protrudes from the tip of the in-
sertion needle and is bent backward on the Teflon coating to
prevent breakage of wire strands. The inner lip of the needle
can also be beveled to further ensure that breakage of the
sphenoidal wire does not occur. (From reference 24, with per-
mission.)

330 / CHAPTER 15
only the ictal data are written out on paper for interpre-
tation. Seizures arc identified by continuous direct ob-
servation, or via video monitors. Patients can also signal
the occurrence of an aura with a call button. When sei-
zures occur, trained staff examine patients during the
events and their examinations are also recorded on the
videotape. In addition, subclinical electrographic ictal
EEG discharges may be captured by an automatic sei-
zure detector and by random searches. A ti1ne—code gen-
erator records clock time simultaneously on the video
image and on one channel of the EEG so that electrical
activity and behavior can be correlated exactly. Fifteen,
thirty, or more channels record EEG in common refer-
ence format so that seizures can then be played back in
any desired montage (125). Records are reviewed daily
by an electroencephalographer/neurologist and deriva-
tions may be changed if needed to better display any
abnormal activity observed.
The primary purpose of EEG telemetry with video
monitoring is to localize the site of onset of spontane-
ously occurring ictal EEG discharges, and to correlate
this with ictal behavioral changes. Anticonvulsant drugs
are cautiously tapered only if necessary, since this may
rarely precipitate atypical ictal events (126). Seizures are
occasionally activated by sleep deprivation, exercise, or
prolonged hyperventilation, when they do not occur
spontaneously.
Automatic spike detection programs are also available
for quantifying interictal spike frequencies at various lo-
cations (127). The site of maximum interictal spike oc-
currence, particularly those spikes recorded during
wakefulness (68,128) and REM sleep (129) correlates
well with the site of ictal onset.
Evaluation 0fEpileptif0rm Activity
Ictal EEG changes can be observed with scalp and
sphenoidal electrodes in most patients during complex
partial seizures, although isolated auras or other simple
partial seizures are only rarely accompanied by identifi-
able EEG abnormalities. Sorne examples of ictal onsets
recorded during scalp and sphenoidal EEG telemetry ap-
pear in Figure 4. The most easily recognized focal ictal
EEG onsets are localized to sphenoidal derivations, but
even these can be misleading due to propagated activity
from primary epileptogenic regions beyond the range of
recording electrodes (23,130). Two specific ictal onset
patterns shown in Figure 4 have equally reliable localiz-
ing value. Both depend upon the occurrence ofrhythmic
activity of 5 Hz or faster, with phase reversal in one
sphenoidal electrode (130). When this pattern is the first
ictal change observed, or occurs after other changes that
are localized to the same sphenoidal electrode, it is re-
ferred to as an initial focal onset. When the pattern is
seen within 30 seconds after a diffuse ipsilateral, or gener-
alized ictal change, it is referred to as a delayed focal
onset. Since both initial and delayed focal patterns have
the same localizing value, we no longer consider it i1n—
portant to require that ictal EEG changes precede ictal
behavioral changes when analyzing scalp and sphenoi-
dal—recorded data. Both patterns are correct in identify-
ing the epileptogenic region demonstrated subsequently
by depth electrode evaluation in only about 85 percent
of patients, however. Consequently, confirmatory data
from other independent studies are also necessary.
When a consistent initial or delayed focal ictal EEG
onset is recorded from one sphenoidal electrode and a
preponderant interictal EEG spike focus is also identi-
fied in the same area, the patient may be considered for
surgery without intracranial evaluation if the criteria for
confirmatory evidence of focal functional deficit de-
scribed later are met. The number of seizures required to
conclude that ictal onsets are consistently focal is not
fixed and is determined in part by the nature of the pa-
tient's habitual seizures. If more than one habitual sei-
zure type has been reported, examples of each type
FIG. 4. Examples of EEG telemetry—recorded ictal onsets from four patients with complex partial sei-
zures. (A) Low—voltage 6 to 7 c.p.s. rhythmic activity appears at the right sphenoidal electrode (arrow) 5
sec before it is seen over the right temporal convexity. (B) Following a diffuse burst of muscle and eye
movement artifact, low—voltage 5 to 6 c.p.s. activity is recorded by the right sphenoidal electrode (arrow).
This becomes progressively slower and the amplitude increases; 5 sec later it is seen diffusely over the
right hemisphere. (C) Irregular, sharply contoured slow waves demonstrate phase reversal at the right
sphenoidal electrode (arrow) and are reflected as low—amplitude delta, without phase reversal, overthe
right hemisphere. (D) In this lateralized but not localized ictal onset, voltage suppression and low—voltage
fast activity occur over the entire right hemisphere, although they are best seen at the right sphenoidal
electrode (arrow). This precedes by 3 see the appearance of diffuse 3/sec spike and wave discharges,
which are also more prominent from the right frontotemporal and sphenoidal derivations. After 1 0 see,
this latter activity evolves into high—voltage 7/sec sharp waves, which show phase reversal at the right
sphenoidal electrode and laterally at the right anterior to midtemporal region. The 5 to 7 c.p.s. patterns in
(A) and (B) illustrate an initial focal pattern and in (D) a delayed focal pattern, both of which correlate
highly with ipsilateral mesial temporal ictal onsets identified with depth electrode recording. The slower
focal rhythmic pattern in (C), however, has less localizing value. Calibration 1 sec, 100 nV. Note that
sensitivity is the same for A, B, C, and the first half of D but is decreased to half in D at the first calibration
mark. (From reference 99, with permission.)

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332 / CHAPTER 15
should be recorded. It is most important to be certain
that the seizures captured on the telemetry unit are the
seizures causing the patient's problems at home. If neces-
sary, videotapes can be shown to family or friends for
verification. Additional tests are then performed during
phase 1 to obtain confirmatory evidence of dysfunction
at the site of ictal onset.
Evaluation ofFocal Functional Deﬁcits
FDG—PET and neuropsychological evaluations are
important confirmatory tests of focal functional deficit
that are performed on an outpatient basis and have al-
ready been described. Two other tests, thiopental activa-
tion and the intracarotid sodium amytal procedure
(IAP), require hospitalization and are usually done dur-
ing the phase 1 telemetry admission if ictal onsets are
focal.
Barbiturate narcosis is often used in order to activate
interictal EEG spike activity, although EEG spikes that
occur during slow—wave sleep have less localizing value
than those that occur during wakefulness (128). This test
is useful, however, because focal attenuation of barbitu-
rate—induced fast activity implies a functional deficit that
may indicate the site of the epileptogenic region
(45,131,132). We prefer to use intravenous thiopental
given at a rate of 25 mg every 30 seconds until adequate
fast activity is produced in the EEG (usually 200 to 300
mg). This drug is considerably more effective than seco-
barbital because it provides more control over the level
of consciousness, and the observation time is longer than
with the faster acting methohexital. In patients with
complex partial seizures, focal attenuation is most often
isolated to one sphenoidal electrode (Fig. 5); this finding
correlates well with the presence of a mesial temporal
lesion on that side, usually mesial temporal sclerosis
(45,131,132).
The intracarotid sodium amobarbital procedure was
originally done to lateralize hemispheric dominance for
language (133), and was later used to predict whether the
contralateral temporal lobe could support memory after
anterior temporal lobectomy (107). Further research has
shown that an induced transient global memory deficit,
following pharmacological ablation of one hemisphere,
correlates with the presence of an epileptogenic lesion in
the contralateral temporal lobe (134). In addition, patho-
logic shifting of language dominance from the left to the
right hemisphere generally indicates that the epilepto-
genic lesion is in the left temporal lobe (135).
Before the patient undergoes IAP, angiographic stud-
ies are recommended to provide information about the
perfusion pattern of the drug. These studies may also
identify arterial anomalies that would put the patient at
risk. Before injection of sodium amobarbital, baseline
measurements are made of the patient's language and
memory functions to serve as a comparison for drug—re—
lated behavior changes. Immediately prior to injection,
the patient is asked to count aloud while bilateral grip
strength is continuously assessed. Over a 4—second pe-
riod, 125 mg of sodium amobarbital in 10 cc of saline
solution is injected into one internal carotid artery via a
transfemoral cannula. Each hemisphere is infused sepa-
rately, with at least a 30-minute delay between injec-
tions. EEG is simultaneously recorded, and the neurolog-
ical status of the patient is continuously monitored. The
critical postinjection period for behavior assessment is
during the d1ug—induced marked unilateral EEG delta
slowing and hemiparesis. This period typically does not
last longer than 3 minutes. Within seconds after the doin-
inant hemisphere injection, cessation of counting occurs
and marked aphasia is immediately apparent, varying
from mutism to perseverative speech.
Initial aphasia testing is carried out in the first minute
after injection. The examination assesses expressive and
receptive language skills and includes naming, reading,
and responses to simple commands. Following this,
items to be remembered are presented. Memory for
these items is tested following return of EEG and behav-
ior to baseline, and at least 10 minutes postinjection.
The type of item presented should be appropriate for the
hemisphere being assessed. For instance, memory for
verbal material, either visually or aurally presented, is
not expected to be intact following a dominant hemi-
sphere injection. More detailed descriptions of the
IAP assessment procedure have been published else-
where (136).
Skull roentgenograrns, XCT, MRI, and cerebral an-
giograms are also obtained during phase 1 ifthese studies
have not been carried out previously. Nonspecific struc-
tural abnormalities revealed by these studies provide
useful confirmatory information if their localization cor-
relates with the site of EEG—demonstrated epileptiform
activity, although these structural findings alone do not
necessarily indicate an epileptogenic lesion (23,74). As
noted earlier, the pathological correlates of high—inten—
sity areas in T2—weighted MRI scans remain unclear
and these abnormalities should be interpreted with cau-
tion (7 8).
Indications for Further Procedures
If a patient has a well—localized EEG—recorded ictal
onset (130), FDG—PET scans demonstrate a hypometa—
bolic zone in the same area, and there is no conﬂicting
localizing information from structural imaging, other
tests of focal functional deficit, or seizure semiology, a
standard anterior temporal lobectomy is recommended

FIG. 5. Simultaneous sphenoidal, nasopharyngeal, and temporal scalp recordings during thiopental
injection. Note attenuation of low—voltage fast activity recorded at the left sphenoidal electrode (channel!
3 and 4), but not at nasofhaiéyngeal or scalp derivations. Calibration 1 sec, 100 yuV. Patient had menial
temporal sclerosis on let. ( rom reference 99, with permission.)

334 / CHAPTER 15
at UCLA without requiring phase 2 (243). Clear struc-
tural lesions on MRI and XCT can be substituted for
FDG-PET evidence of hypometabolism, but further
studies are necessary to determine when other tests of
focal functional deficit may serve this purpose.
When patients fail to meet the criteria for surgical re-
section after phase 1 evaluation, they may be considered
for phase 2 studies if seizures appear to be stereotyped
and the data collected during phase 1 allow a hypothesis
limiting possible epileptogenic regions to a few that can
be adequately explored with intracranial recording. If
the seizures are complex partial and a limbic onset is
suspected, depth electrodes are usually recommended. If
phase 1 has clearly lateralized the epileptogenic region to
one hemisphere and it appears to be in the lateral neo-
cortex, subdural grid electrodes are preferred.
When phase 1 evaluation indicates that seizures are
occurring from multiple sites, or no localizing hypothe-
sis can be derived, patients might still be considered for
large multilobar resections, hemispherectomy, or corpus
callosum section. These aggressive procedures are most
often justified in infants and small children in whom the
seizures are life—tl1reatening or the likely cause of severe
developmental delay (137,13 8). Unilateral regions of hy-
pometabolism on FDG-PET that correlate with the pre-
dominance of interictal and/or ictal epileptiform EEG
discharges are the most important criteria for consider-
ing large resections in these patients (87,139), while drop
attacks as the major cause of disability are the primary
indication for callosotomy (140). Further work—up in
these patients may include spike—suppression tests (141),
and more speciﬁc psychological and psychosocial evalua-
tions. Patients undergoing hemispherectomy must ei-
ther have a useless contralateral hand or, in rare in-
stances, be willing to accept this deﬁcit as an inevitable
consequence of the surgical procedure. Patients who in-
tend to undergo corpus callosum section must under-
stand that this is a palliative procedure that is unlikely to
abolish all ictal behaviors. There is some evidence that
patients with ipsilateral hand and language dominance
are at greater risk for disabling postoperative disconnec-
tion symptoms (142), but this is not considered an abso-
lute contraindication to callosotomy. Most centers
prefer to carry out partial callosotomy, commonly the
anterior two—thirds, which is usually effective without
causing a disconnection syndrome. Ifdrop attacks per-
sist, the section can be completed later with minimal
symptoms of disconnection.
Phase 2 (Intracranial EEG Telemetry)
General Considerations
Due to the serious risk (but low incidence) of injury
from chronic intracranial electrode recording, only pa-
tients who appear very likely to benefit from surgical
treatment are selected for phase 2. For this group, when
phase 1 evaluation fails to localize a surgically resectable
epileptogenic lesion, intracranial recording offers a great
diagnostic advantage. With depth or subdural grid elec-
trodes, the ictal EEG recording is generally free of mus-
cle and movement artifacts, making it possible to ob-
serve exquisitely focal types of ictal onset and to follow
the spatiotemporal pattern of electrographic propaga-
tion. However, such focal onsets are observed only when
a recording electrode is at, or very close to, the primary
epileptogenic region. Since only a limited number of in-
tracranial electrodes can be safely placed, the number of
potential locations of the epileptogenic region should be
reasonably narrowed by the phase 1 evaluation before
these invasive procedures are contemplated.
EEG with stereotactically placed depth electrodes
(SEEG) is most frequently employed in patients with
complex partial seizures ofpresumed limbic origin when
(1) clear EEG lateralization of the ictal onset has not
been obtained; (2) EEG-recorded ictal onsets are well
lateralized but equally prominent in extratemporal and
temporal regions; (3) EEG-recorded ictal onsets are well
localized to one temporal lobe but confirmational evi-
dence of focal dysfunction or a structural lesion is miss-
ing or conflicting; (4) EEG-recorded ictal onsets are
clearly localized to one temporal lobe but other studies
and/or the clinical seizures (e.g., simple partial motor or
special sensory) suggest an extratemporal disturbance; or
(5 ) phase 1 evaluation suggests an epileptogenic region in
one temporal lobe that should be treated by a larger, or
more limited, resection than the standard anterior lobec—
tomy. In patients who may be candidates for selective
amygdalohippocampectomy or lateral temporal resec-
tion, depth electrodes are used to confirm that ictal on-
sets arise from the area of planned removal.
Chronic recording with intracranial subdural grid
electrodes usually is utilized when (1) EEG and MRI
lateralization of the epileptogenic region has been ob-
tained and additional localization is necessary between
lobes or within a large area ofcortex, and (2) localization
of essential cortex is necessary to avoid deﬁcit during
resection of nearby seizure foci. The ability of subdural
grids to localize limbic ictal onsets is unknown. The rela-
tive advantages of grids versus depth electrodes is an area
of active investigation.
There are some general contraindications that relate
to the safety of intracranial electrode EEG recording
over a number ofweeks. Patients who have serious multi-
ple illnesses or active infections that could lead to intra-
cranial infections, or who are otherwise poor surgical
risks (e.g., patients with diabetes mellitus who are prone
to infection) obviously should not undergo chronic intra-
cranial EEG. Also, certain skull defects (e.g., thinning of
the bone or a prior craniotomy) make depth electrodes
unstable and therefore unsafe. During phase 1 studies,

our patients are closely ObS61'V6Cl for emotional instabil-
ity, psychiatric disorders, or unusually violent ictal be-
havior, which would not allow them to tolerate phase 2.
Careful attention is devoted to ensuring that patients
and/or their parents have a full understanding of the
purposes and risks involved in these procedures as a
measure of obtaining full consent.
Methods ofElectrode Implantation and Removal
Stereotactic Depth Electrode Implantation
Recent developments in neuroimagin g have radically
changed the field of Stereotactic surgery. MRI now al-
lows direct visualization ofbrain stiuctures in any plane.
By choosing speciﬁc pulse sequences, MRI can delineate
brain—CSF boundaries, grey and white matter junctions,
and even discrete pathological changes within deep cere-
bral regions. We now use a method of electrode i1nplan—
tation based essentially on MRI guidance, Stereotactic
digital subtraction angiography (DSA), and Stereotactic
FDG—PET; these neuroimaging studies arc integrated in
a computerized i1nage—analysis system that allows pre-
surgical planning of electrode implantation. This stereo-
tactic technique is made possible by an MRI—co1npatible
lightweight Stereotactic frame that is used for imaging
studies and intraoperative implantation, and for postop-
erative verification of electrode placement. The overall
principle remains to survey the limbic stiuctures medial
to the temporal lobe from anterior to posterior, bilater-
ally and symmetrically (15). Additional extratemporal
stiuctures are selected for implantation according to sei-
zure seiniology, scalp EEGs, and/or hypometabolic ar-
eas on FDG—PET.
A modified Leksell Stereotactic frame (the OBT, Tipal
Instiuinents, Montreal, Canada) (143) is used for target
localization and electrode implantation (Fig. 6). It is con-
stiucted of electrically nonconducting material that is
compatible with CT, MRI, and DSA. With additional
modifications made at UCLA (l44.l45), Stereotactic
PET can also be obtained. Targets are reached from a
lateral orthogonal approach in a system of Cartesian co-
ordinates, where the X axis is along the anteroposterior
(sagittal) plane of the frame, the Y axis is along the infe-
rior to superior (coronal) plane, and the Z axis is in the
axial plane, extending positively to the right and nega-
tively to the left.
Four sets of Plexiglas® plates provide fiducial markers
on each side and top of the Stereotactic frame. Three
contain a Z—shaped channel filled with an appropriate
contrast material for each image modality and are te1npo—
rarily attached to the Stereotactic frame. Aluminum tub-
ing is used during CT scanning, copper sulfate solution
(7 gm/ 1) is used for MRI studies, and for PET scans the
channels are ﬁlled with positron—emitting germanium
isotope. The plane of section is calculated from the loca-
THE EPILEPSIES / 335
>i!p'
FIG. 6. The OBT (modified Leksell) frame used for intracere-
bral target localization and depth electrode implantation. Ste-
reotactic brain images obtained with magnetic resonance,
computerized tomography, digital angiography, and positron
emission tomography are artifact-free.
tion of the center arm ofthe Z—shaped marker in relation
to the two parallel end bars. For DSA studies, the fiducial
markers consist of four 1 —mm stainless steel disks placed
equidistantly at the four quadrants of the Plexiglas plates
located on either side of the head for a lateral view, or at
the front and back of the frame for an anteroposterior
view. Markers closest to the x—ray source will form a
larger rectangle on the x—ray film because ofbeam diver-
gence, and thus differentiate the side injected and pro-
vide data for computer analysis of depth of field.
The procedure per se is divided into three stages: (1)
Stereotactic imaging, (2) computerized image analysis,
and (3) Stereotactic implantation.
1. Stereotactic imaging. The Stereotactic frame is
placed on the patient's head using local anesthesia sup-
plemented with short-acting neuroleptics. Initially, the
frame is positioned over the head using auricular pins,
then five twist—drill holes are made in the outer table of
the skull at the front, back, and midline. Five MR—co1n—
patible carbon fiber pins are placed in the drilled holes
and secured to the frame. A memory ring is placed on
each pin at the outer portion of the frame to permit exact
repositioning of the frame for any future surgical proce-
dures. The patient is then brought to the MRI suite and
placed in a supine position, with the Stereotactic frame
anchored to a custom frame adaptor over the sliding ta-
ble of the MRI. Sagittal, coronal, and axial Stereotactic
MR images are obtained on a 0.3 Tesla unit. We use a
custom surface coil that fits closely around the frame to
increase the signal—to—noise ratio. Inversion—recovery se-
quences with a slice thickness of 4.9 mm and slice inter-
vals of 5.1 mm are obtained. Three excitations are used
in the coronal plane, and two in the axial and sagittal
0 planes. A Stereotactic digital angiogram in both antero-
posterior and lateral projections is obtained using a stan-
dard femoral catheterization approach. Four—per—second

336 CHAPTER 15
aiterial and Venous phases are selected for further analy-
sis. Finally, a stereotactic FDG—PET is performed. A
frame adaptor allows fixation to the tomograph sliding
table. The patient is injected with 5 1nCi of FDG, and 15
simultaneous axial planes with a center—to—center inter-
slice distance of 6.75 1n1n are obtained 40 minutes later.
Images are reconstructed by filtered backprojection to
an image with in—plane resolution of approximately 5 X
5 1n1n. The head—frame is then removed.
2. Computerized image analysis. All stereotactic digi-
tized imaging studies are analyzed after being transferred
to a central workstation. Image data such as size, slice
thickness and intervals, ﬁeld of View, and orientation are
included. Surgical planning and selection of recording
sites are made at the central workstation using i1nage—
analysis software. Selected images are retrieved from the
hard—disk memory and are simultaneously displayed in
separate windows (Fig. 7). Different planes from a single
FIG. 7. Multimodal stereotactic imaging system. Top: Different planes ofdifferent studies can be simulta-
neously displayed on the computerized workstation terminal. Bottom: Post—implantation MR, seen here
in the coronal plane, is used to verify accurate electrode placement. (From reference 145, with permis-
sion.)

modality or rnultirnodal images can be displayed and
analyzed at the same time. A cursor system intercon-
nects the images and the X, Y, and Z coordinates of any
point within the stereotactic frame can be displayed. Ini-
tially, structures are selected on the sagittal MR; orthogo-
nal trajectories are simulated to sample both lateral tern-
poral neocortex and mesial temporal structures
(amygdala; anterior, mid, and posterior hippocampi;
and anterior, mid, and posterior parahippocampal gyri).
Labeled targets are automatically transposed to the coro-
nal and axial MR, and the Z coordinate, denning the
depth of implantation, is then determined. Next, phases
of the arterial and venous angiograrn are selected and
trajectories are corrected within an avascular window.
Extratemporal targets are usually the orbito—frontal cor-
tex, the supplementary motor area, the anterior and pos-
terior cingulate gyri, or the occipital cortex. After corn-
pletion of the target localization, a printout of all
coordinates is obtained.
3. Stereotactic implantation. Under general anesthe-
sia, at a subsequent surgical sitting, the stereotactic
frame is replaced over the patient's head using the pre-
measured skull—fixation pins and the position confirmed
with a portable skull x—ray. The frame is clamped to a
supportive device attached to a Mayfield holder. A rnodi—
ﬁed side—canier that slides on vertical side bars is posi-
tioned at the predetermined X and Y coordinates and
serves as a key landmark for measurement of electrode
length to reach the Z coordinate. The skin and skull are
penetrated from an orthogonal approach without
breaching the dura, which is carefully perforated with a
thin electrocautery, stopping at the subdural space. A
self—tapping MR—compatible titanium guide—screw is
then secured to the skull. The distance between the outer
portion of the screw and the side—carrier is translated into
a specific length for each electrode. Temporal electrodes
are multicontact rigid tubing with an outer diameter of
0.8 mm. The electrodes are constructed with MR—corn—
patible nickel chromium and have a hollow center per-
mitting insertion of platinum alloy fine wire (40—micron
diameter) electrodes. Extratemporal electrodes are ﬂexi-
ble nichrome fine wires (100—micron diameter) with
multicontact leads. Two reference electrodes are placed
in the galea. After placement, electrodes are bent toward
the vertex and embedded in a thin mold of acrylic poly-
mer. Additionally, stereotactic subdural strips of six or
eight platinum disc electrodes imbedded in silicone
(146) can be inserted over the convexity or the mesial
aspects of both hemispheres, when seizures are also sus-
pected of having a frontal or parietal lobe origin. This
can be accomplished by knowledge of the locations of
major draining veins from the stereotactic angiography.
Subdural strips are used as sentinel electrodes to sample
certain areas presumed to be involved in seizure onset
that are poorly sampled by the orthogonally placed
depth electrodes. The frame is removed postoperatively,
THE EPlLEPSlES / 337
and the patient is transferred to the neurosurgical inten-
sive care unit for overnight observation. The patient is
sent to the telemetry unit when stable. Electrodes are
removed under local anesthesia after completion of the
monitoring period. Resective surgery is performed a few
months after removal of the electrodes to allow wound
healing and reduce the risk of infection.
Subdural Grid Implantation
This technique requires an initial craniotomy for the
insertion of multiple arrays of electrodes over the cortex
in the subdural space (18,147). Wide areas of lateral cor-
tex can be sampled as well as subtemporal, suboccipital,
orbito—frontal, mesial frontal, cingulate, mesial parietal.
or occipital areas. The grids are made of silicone and
contain up to 64 platinum discs, each with a diameter of
5 mm and a center—to—center interelectrode distance of
10 mm. After intraoperative definition of the sensorimo—
tor cortex with evoked responses, lateral coverage of the
central area, including peri—sylvian cortex, opercular
frontal, and superior temporal gyri, is obtained with a
single 64—contact grid. Additional grids are inserted to
sample speciﬁc lobes according to the desired presurgical
evaluation. Great care must be taken to avoid any tear or
displacement of major draining veins. The grids are tied
to each other to prevent movement or slippage. The con-
nectors are then tunneled under the skin through sepa-
rate incisions. An intracranial pressure monitor is also
placed to indicate significant postoperative cerebral
edema. The dura is closed in a water—tight fashion, and
the bone ﬂap sutured in place. Corticosteroid adrninistra—
tion and ﬂuid restriction are used initially to allow ex-
pansion of the subdural space and accommodation of
the brain to the grids. Patients are then taken to the neu-
rosurgical intensive care unit before transfer to the telem-
etry ward for functional mapping and seizure rnonitor—
ing (18,148).
Depth Electrode Evaluations
During the ﬁrst postoperative day, while the patient is
still in intensive care, prolonged direct SEEG (hardwire)
recordings are made to survey all depth electrode con-
tacts, as well as any subdural strip electrodes that may
have been inserted. Chain—linkage, common reference,
and bipolar recordings are obtained using a 21 —channel
EEG machine. Patients are then transferred to the telern—
etry unit for SEEG telemetry and video monitoring in
order to capture spontaneous seizures and perform other
studies. If indicated by the incidence of seizures during
phase 1 telemetry, anticonvulsant medications are
slowly tapered. During SEEG telemetry, ictal EEG and
behavioral data are gathered and seizures are detected as
described for phase 1. In addition, an automatic seizure

338 / CHAPTER 15
detector is used to identify ictal SEEG discharges that
might otherwise go unnoted (149,150). Subclinical elec-
trographic ictal events are also more commonly encoun-
tered with randoin searches during phase 2 than during
phase 1. Initial SEEG recordings are made using 30-
channel montages containing symmetrical derivations
from each hemisphere, including the most mesial and
most superficial contacts from temporal and extratem-
poral electrodes and any subdural strip electrodes. After
several typical episodes are recorded and the electrogra—
phic pattern is determined, montages may be changed to
define better the site of ictal onset. Even with 30 tele1ne—
try channels, not all depth electrode contacts can be sur-
veyed in the initial montage. Additional contacts may
need to be included later, as well as scalp and sphenoidal
derivations if needed to identify surface correlates. Focal
onsets are most clearly displayed by recording from the
bipolar tip of each depth electrode.
Mesial temporal EEG—recorded ictal onsets are called
focal (1 5 1) and considered to be localizing when they are
stereotyped; when only one or two electrode contacts are
involved initially; and when there is a clear progression
of the epileptic discharge, first to ipsilateral and then to
contralateral structures, which can be correlated te1npo—
rally with the progression of behavioral ictal events (Fig.
8A—C). Often, however, the initial EEG changes are
more difficult to interpret, due to subtle focal onsets that
may be missed, or regional onsets (151) that initially in-
volve all, or most, depth contacts in one temporal lobe
simultaneously (Fig. 8D—F).
With our present knowledge, it is impossible to charac-
terize definitively and classify all SEEG—recorded ictal
phenomena. Although certain patterns may be corre-
lated with good or bad prognoses (152,153) and various
pathologic findings (154), there is much yet to be learned
about the neuronal events recorded by the ictal SEEG,
and the ultimate clinical signiﬁcance of the abnor1nali—
ties revealed by this technique. Almost every patient we
FIG. 8. Segments of SEEG telemetry—recorded ictal onsets from six patients. These tracings represent
examples of progressively decreasing localizing value. (A) Very low—voltage fast activity begins (arrow) at
the left anterior hippocampal pes (LAH) and continues for 1 7 sec before it is barely seen in other areas.
(B) Low—voltage fast activity of much lower frequency than that seen in A begins (arrow) at the left
posterior hippocampal gyrus (LPG) and appears in all depth leads on the left after 5 sec. (C) 4 to 5/sec
sharp activity begins in the right middle hippocampal pes (RMH) (arrow) and 1 sec later is slightly re-
flected in all right depth electrodes. (D) Sharp activity begins with phase reversal in the left posterior
hippocampal pes (LPH) (arrow) and remains most prominent there, although it is reflected in all the other
depth electrodes. (E) lctal rhythmic activity first appears in the left middle hippocampal gyrus (LMG) and
later spreads to other depth electrodes; this is preceded by a regional suppression (arrow) involving all
left temporal depth electrodes. (F) lctal discharges begin with irregular regionally synchronous spike,
polyspike, and slow—wave bursts followed by a build—up of low—voltage fast activity, which is also synchro-
nous in both hippocampal pes and gyrus. (Note: R, right; L, left; AMYG, amygdala; A, anterior; M, middle;
P, posterior; H, hippocampal pes; G, hippocampal gyrus.) Calibration 1 sec. For each sample, the eight
channels not shown recorded from homologous contralateral depth sites, extratemporal, skull, and
sphenoidal derivations. (From reference 99, with permission.)

see appears to be unique, and each SEEG evaluation
seems to present a new set of confounding issues.
In general local onsets appear to indicate reliably that
the electrode contact is near the epileptogenic region,
while regional onsets tend to represent epileptiform activ-
ity propagated frorn a primary epileptogenic region dis-
tant from the available recording sites. Usually, how-
ever, this distant region is still within the same temporal
lobe. Consequently, a regional onset is not a poor prog-
nostic sign unless there is other evidence that this repre-
sents propagation from an extratemporal or contralat—
eral epileptogenic region. The finding of a regional onset,
however, should prompt more careful attention to this
possibility. The pattern of ictal propagation also pro-
vides clues to the site of seizure generation. In particular,
slow spread to contralateral limbic structures is typical of
mesial temporal seizures, while rapid contralateral
spread suggests a neocortical or extratemporal site of on-
set (153). Frontal depth or strip electrodes are useful not
only to rule out a frontal onset, but to demonstrate the
delayed ipsilateral frontal projection typical of mesial
temporal seizures (155). The differentiation between pri-
mary and propagated ictal discharges remains a prob-
lem, and sampling errors from the necessarily limited
electrode array can result in false localization.
In our experience, SEEG—recorded ictal data are still
the most reliable indicators of the location of the epilep-
togenic region, but confirmatory evidence of focal dys-
function is also sought during the phase 2 evaluation.
Additional functional information can be obtained by
studies that take advantage of the use of depth electrodes.
Whereas focal nonepileptiform abnormalities of base-
line rhythms are rarely seen during scalp EEG recordings
in our patients, there is often localized slowing or attenu-
ation of normal rhythmic activity recorded from intra-
cranial electrodes. Attenuation of normal SEEG—re—
cordcd faster rhythms is most reliably observed when the
placement of relatively equidistant multiple depth elec-
trodes is bilaterally symmetrical, and chain—linkage
montages are used (Fig. 9). Consistent attenuation of
THE EPILEPSIES / 339
normal rhythmic activity at most, or all, mesial temporal
depth electrodes on one side indicates a functional dis-
turbance that correlates well with the presence of a lesion
(23). Attenuation of barbiturate—induced fast activity in
one temporal lobe is much better revealed when intrave-
nous thiopental is given during SEEG recording than
during scalp and sphenoidal EEG, as described earlier.
Unilaterally attenuated SEEG—recorded thiopental—in—
duced fast activity also correlates well with the presence
of a lesion (23,132). Thiopental—induced interictal SEEG
spikes, like spontaneous spikes, are not reliably localiz-
ing when recorded from the temporal depth.
Electrical stimulation has been used extraoperatively
and intraoperatively to produce seizures as a means of
localizing a potential epileptogenic zone; however, local-
ization obtained frorn electrically induced events (as
with convulsant d1ug—induced seizures) may differ from
localization obtained from spontaneous events (156). De-
terminations of electrically induced afterdischarge
thresholds have been used to indicate the location of epi-
leptogenic tissue, but results are contradictory. At
UCLA, afterdischarge thresholds have been most consis-
tently elevated in the epileptogenic hippocampus, partic-
ularly when the lesion is hippocampal sclerosis (157),
while others have found a lowered afterdischarge thresh-
old to indicate epileptogenic brain tissue (158). Differ-
ences in stimulation parameters have been suggested as
one reason for these conﬂicting observations (158).
Intracarotid amobarbital testing is always done as the
last study of phase 2, even if this test was carried out
during phase 1, to be certain that no significant impair-
ment of memory function has been produced in the con-
tralateral temporal lobe as a result of electrode irnplanta—
tion and/or stimulation.
Subdural Grid Evaluations
From extensive experience with temporal limbic epi-
lepsy, we have learned that the highest degree of surgical
FIG. 9. Direct (hardwire) SEEG record-
ing demonstrates attenuation of nor-
mal rhythmic fast activity in the right
amygdala, hippocampal pes, and
gyrus. Abbreviations as in Figure 8,
except P, hippocampal pes. Calibra-
tion 1 sec, 1 ,00O/j. V. Patienthad me-
sial temporal sclerosis on the right.
(From reference 99, with permission.)

34O CHAPTER 15
success is achieved when there is preoperative dernonstra—
tion IMR. CT. SPECT, PET) of a pathological substrate,
proof of epileptogenesis in this same region, and com-
pleteness of the operation with postoperative pathology
found in the specimen. Similarly, in neocortical epi-
lepsy, it has long been known that surgical outcome is
best when a speciﬁc lesion can be demonstrated preoper-
atively. When extratemporal localization is obtained by
scalp EEG techniques alone, in the absence of a lesion, it
is too often incorrect. Furthermore, the absence of a
pathological substrate in the postoperative specimen will
correlate with a poor outcome.
Traditional methods elaborated by Penfield and his
colleagues utilized intraoperative electrocorticography
to identify interictal spiking discharges and direct bipo-
lar electrical stimulation of the brain to demonstrate the
epileptogenic cortex and functional regions acutely in
the operating room (159). Talairach and colleagues dern—
onstrated the irritative cortex, lesional cortex, and epilep-
tic co rtexusing depth electrodes (14). However, the nurn—
ber of electrodes that can be used is limited. These
regions can now be easily denned using implanted large
subdural grids. Since these electrodes cannot be moved
after implantation, a large array is necessary and sub-
dural strip electrodes are inadequate for this purpose.
The opportunity provided by implantation enlarges the
scope of the investigation. Children and adults who for
various reasons cannot tolerate a prolonged operative
procedure under local anesthesia can now be cornfort—
ably evaluated (160,161).
In addition to localizing interictal and ictal epilepti-
form discharges using telemetry monitoring techniques
identical to those of depth electrode recordings, the ex-
tent of the functionally inactive region can be tested by
electrical stimulation, evoked potentials, and EEG back-
ground activity (Fig. 10). The functionally active cortical
area may be found to be displaced by the pathology. The
specific procedures of functional mapping using chronic
subdural electrode grids are dealt with in detail elsewhere
(l8,l48,l62). Both cortical stimulation and event—re—
lated evoked potentials are utilized to localize essential
cortical regions. The parameters for cortical stimulation
are selected to avoid tissue damage. No simple rules exist
for safe parameters for functional mapping by cortical
stimulation. The specific parameters that are safe vary
with the specific electrode size and circuit, and must be
calculated by the physician performing the stimulations
(163). We define essential cortex as that tissue that must
be spared to avoid gross neurological deficit in sensori—
motor function and language. We assume that if careful
neurophysiologic assessment were performed, most, if
not all. brain tissue would be eloquent, and some rneasur—
able deficits would be identified after most focal exci-
sions of brain tissue. As is done with those patients who
undergo depth electrodes, the patient is informed that to
treat the seizure (a global positive deficit), he or she
usually must accept a selective deficit (a limited negative
deficit). Functional mapping is designed to localize cor-
tex that is essential to avoid deficits in activities of daily
living such as hand function and language. As many rele-
vant functions are tested at a site as feasible within the
time limitations and tolerance of the patient. Functional
mapping usually takes about a week to perform and re-
quires much patient cooperation. Not all patients are
capable of tolerating this procedure.
In the preceding era of epilepsy surgery, any interven-
tion into the primary cortices was generally avoided.
With increased confidence in cortical mapping, opera-
tions now often involve these primary cortical regions.
However, in our opinion it is not sufficient to remove
lesions alone; the resection must also include the epilep-
togenic cortex. The definition of epileptogenic cortex by
means of interictal epileptiform discharges and record-
ing of the ictal activity is still under development. In
some cases, focal ictal discharges have been quite limited
in extent and the subdural grid evaluations have allowed
less—than—lobar resection to be surgically successful and
with less than the expected morbidity.
Indications for Further Procedures
Unlike phase 1, where a specific protocol has been
established at UCLA for selection of surgical candidates,
the decision to carry out a resection after phase 2 is not
based on firm criteria. Ideally, all seizures should origi-
nate in one area of the brain and confirmatory tests
should reveal focal dysfunction in the same area. After
grid recording, tailored resections are determined pri-
marily by the pattern of ictal onset and early spread, and
designed to avoid essential cortical tissue. With SEEG
recording, a few complex partial seizures originating con-
tralateral to the presumed epileptogenic lesion (espe-
cially if these seizures are atypical and/or occur when
anticonvulsant medications have been signiﬁcantly low-
ered) are not considered an absolute contraindication to
surgery, since patients with such findings often do well
postoperatively (126). In our experience, when SEEG-
recorded ictal onsets have been focal, there is rarely, if
ever, conﬂicting evidence of focal dysfunction elsewhere.
However, in some patients, a regional SEEG—recorded
ictal onset has been localized to one temporal lobe but
confirmatory tests suggest the focus may lie in part, or
entirely, outside the standard resection. In these cases,
particularly if functional mapping of primary cortex is
also necessary, a second phase 2 with subdural grid elec-
trodes or intraoperative corticography may be recorn—
mended. When the time for ictal spread to contralateral.
or extratemporal structures is less than a second, or ictal
onsets are inconsistent or appear only after clinical signs
and symptoms, focal functional deficits are used to sug-
gest other epileptogenic regions that might justify a sec-
ond phase 2 procedure with subdural grids. When ictal
onsets are nonlocalizing, there is no confirmatory focal
dysfunction, and there is no additional evidence to sug-

THE EPILEPSIES / 341
FIG. 1 0. Focal seizure pattern from left frontal lobe. (A) Anteroposterior skull x—ray outline shows coro-
nal placement of electrodes over the left lateral convexity and shows the location of focal seizure onset
(heavy circles) in the lateral inferior frontal region. (B) Lateral skull x-ray outline shows that the zone of
seizure onset is near the speech cortex. Patient had simple partial seizure of forced thought and speech
arrest followed by complex partial seizure with ictal vocalization. (C) Electrographic seizure recording
shows focal onset of low—amplitude fast activity and sharp wave (arrows), followed by sustained high-
amplitude fast activity in the left lateral inferior frontal lobe near Broca‘s area. Previous depth electrode
evaluation documented seizure onset in the left lateral frontal lobe with subsequent spread to mesial
limbic structures after 15 to 20 seconds. Left frontal resection included most of the seizure zone,
extended up to Broca‘s area, and gave significant seizure reduction. Calibration 100 nV, 1 sec. (From
reference 148, with permission.)
gest speciﬁc alternatives to the areas already explored,
surgery cannot be recommended. Surgery is not per-
formed when SEEG-recorded seizures appear to origi-
nate with equal frequency from either side of the brain,
or when subdural grid—recorded seizures originate en-
tirely within primary cortex that can not be removed.
OPERATIVE PROCEDURES
Electrocorticography
In some centers intraoperative ECoG is performed
routinely under local anesthesia f62.63.l20
the extent of resection is determined on the basis of in-
terictal ECOG findings. Since intraoperative ECOG re-
cordings are limited to the area of craniotomy, they can-
not be used to localize an epileptogenic region, but
rather are used to define better the limits of epileptogenic
tissue already localized by other techniques. This proce-
dure may be extremely helpful for certain neocortical
lesions; however, reliable localization of a limbic epilep-
togenic lesion on the basis of the complex interictal epi-
leptiform discharges encountered in the temporal lobe is
much more difficult, if not impossible (62). In fact, inter-
ictal spikes recorded from depth electrodes inserted at
surgery into the hippocampus and amygdala appear to
with QhcAn"i r»i r»athrv|rvmV ’\Vionrroc u/Kila ‘»i-‘i

342 CHAPTER 15
leptiform discharges are not readily recorded from these
structures when hippocampal sclerosis is present (45).
In addition to mapping the distribution of interictal
spike discharges and other spontaneous abnormal activ-
ity, imraoperative recording techniques are useful for de-
fining areas of cortical dysfunction demonstrated by lo-
calized attenuation of barbiturate fast activity induced
by intravenous thiopental. Evoked potential and stimula-
tion techniques are also used to identify primary motor,
sensory, and language cortex when suprasylvian resec-
tions are planned. Intraoperative cortical stimulation
can occasionally induce the habitual aura or behavioral
seizure; however, this should not be considered defini-
tive evidence that the stimulated site is the primary epi-
leptogenic region. Stimulation of distant, or even contra-
lateral, structures having afferent input into the primary
epileptogenic zone can induce an habitual seizure (45).
Nonetheless, valuable information can be determined
from intraoperative electrophysiological studies, and
ECoG procedures remain an important part of the surgi-
cal evaluation for some patients with partial epilepsy.
At UCLA, questions concerning older children and
adults that arise during phase 1 are usually answered by a
phase 2 evaluation in lieu of ECOG. When a standard en
bloc anterior temporal lobectomy is performed, it is
based on data acquired during presurgical evaluation;
intraoperative electrocorticography is rarely necessary.
Similarly, the presurgical evaluation for tailored resec-
tions usually involves chronic subdural grid recording to
delineate the epileptogenic region and extraoperative
functional mapping to identify essential primary cortex,
so that all necessary information for determining the lo-
cation and extent of the resection is derived prior to
operation. Intraoperative ECOG is commonly per-
formed for resections in infants and small children, how-
5cm
ever, where localization is obtained primarily with inter-
ictal and ictal scalp EEG recordings and FDG—PET, but
chronic intracranial evaluation is not done. Occasion-
ally, intraoperative ECoG is also useful in older children
and adults to resolve specific problems that arise during
phase 2 presurgical evaluation.
Operative Techniques
Temporal Lobe Resection
Temporal lobe resection is the most frequently per-
formed surgical procedure in the treatment of partial
epilepsies. Variations in techniques and extent of resec-
tion have been reviewed by Crandall (27). We will pre-
sent here four techniques of temporal resection.
Standard En Bloc Resection
The Falconer—Crandall resection (27,28) of the ante-
rior temporal lobe uses sharp dissection cleaving anato1n—
ical structures of the temporal lobe (Fig. 11). This
method has the following advantages: it is performed
under general anesthesia; it allows fixation of the head
and the use of the surgical microscope; it permits quanti-
fication of the resection for interindividual analysis of
outcome; and it produces a surgical specimen suitable
for further neurophysiological and neuropathological
studies.
The patient is placed in a supine position with the
head at a 45—degree angle away from the side of surgery,
fixed using a three—pin head clamp. The vertex of the
head is tilted slightly downward. The head is slightly
higher than the chest with the table ﬂexed. Steroids, anti-
5cm
FIG- 1 1 - Fdooneren Woe anterior temporal lobectomy. (A) Arteries at risk are the anterior choroidal
artery and the posterior cerebral artery and its branches. The resection of lesser extent refers to the
nondominant lobe. (B) Coronal view of resection. (From reference 27, with permission.)

biotics, and diuretics are used. A bolster is placed under
the ipsilateral shoulder. A question—rnark incision is
used, starting at the zygornatic arch a few millimeters
anterior to the ear, curved superiorly and posteriorly
above the ear, then directed toward the rnidline, curving
anteriorly 4 to 5 cm from the rnidline to end in the fron-
tal area within the hairline. A scalp flap is raised anteri-
orly until the frontal process of the zygorna is palpable.
To avoid injury to the frontalis branch of the facial
nerve, the skin is not elevated along the zygoma. The
ternporalis muscle is incised longitudinally and reﬂected
anteriorly and posteriorly and held with fish—hooks. A
craniotomy is then created using a high—speed drill and
craniotome. Additional bone is removed from the lateral
wall of the middle fossa to obtain adequate exposure of
the anterior temporal area. Antibiotic—soaked sponges
are placed at the perimetry of the craniotomy, and gloves
are washed to remove blood and bone dust to prevent
"aseptic meningitis." The dura matter is incised in a U——
shaped curve hinged just above the location of the syl-
vian fissure.
The cortical incision is measured on the middle tern-
poral gyrus from the temporal tip at 6 cm on the non-
dominant and 4.5 to 5 cm on the dominant side. The
posterior incision is obliquely downward at about 45 de-
grees to spare the primary auditory cortex of the superior
temporal gyrus. This incision is continued anteriorly
within 5 mm from the sylvian fissure, paralleling the
curve of the sphenoid ridge until the ﬂoor of the middle
fossa is reached. The pia and bridging vessels are coagu-
lated with bipolar forceps and sharply incised with ini-
croscissors. Dissection is carried by subpial aspiration
along the anterior portion of the superior gyrus, preserv-
ing the arachnoid layer of the sylvian cistern and middle
cerebral artery branches. Cortex is progressively lifted
until the limen insulae is uncovered above the insula.
The posterior incision is deepened vertically with bipolar
coagulation and suction into the temporal stem and infe-
riorly until the ﬂoor of the middle fossa is reached. The
dissection is carried superiorly until the ependyma of the
temporal horn is opened, when a gush of cerebrospmal
ﬂuid occurs. The surgical microscope is brought over the
surgical field, and self—retainin g retractors are positioned
to elevate the lateral cortex. With rnicrosurgical instru-
ments, the white matter over the roof of the temporal
horn is thinned anteriorly until the tip of the ventricle is
reached. This allows exposure of the lateral hump of the
glistening white hippocampus. The incision is carried
through the amygdala anteriorly until the original ante-
rior incision is reached. No incision is made medial to
the choroid plexus, as this is the location of the optic
tract. The tela choroidea and fimbria—fornix are de-
tached at the choroidal ﬁssure with fine dissection. Great
care is taken to preserve branches from the anterior cho-
roidal artery running close to the optic tract and cerebral
peduncle. The hippocarnpus is transected in a coronal
direction 3 to 3.5 cm behind the tip of the pes hippo-
THE EPILEPSIES / 343
campi at the level of the lateral geniculate body. The
ambiens cistern is entered and small perforating vessels
(the Arnrnon's horn arteries) and arachnoid bridges are
sharply divided at the hippoc ampal sulcus. The posterior
cerebral artery, the anterior choroidal artery and the
third and fourth cranial nerves can be identiﬁed and are
preserved. The uncus is then lifted from its piai bed. leav-
ing the ambient cistern. The posterior transection
through the parahippocampal gyrus is continued until
the posterior incision has reached the ﬂoor of the middle
fossa. The specimen is removed en bloc and sent for
neuropathological and neurophysiological studies (Fig.
12). The surgical cavity is inspected and is completed.
Closure is accomplished in the usual fashion, with the
bone stitched back in place and the muscle and skin
closed in two layers.
Tailored Resection
In a tailored resection, the lateral or mesial extent of
temporal resection varies according to the presence of
interictal abnormalities on the ECoG. This type of resec-
tion is usually performed under local anesthesia to allow
cortical mapping of the sensorimotor area and speech
cortices, if operating on the dominant hemisphere. The
temporal structures are removed in two stages: a lateral
neocortical resection, followed by aspiration—suction of
the mesial structures. This technique has the advantage
of obtaining a cortical map of essential cortex as defined
by acute rnonopolor or bipolar stimulation, which may
facilitate resection of a larger neocortical area or presurn—
ably reduce the severity ofpostoperative neuropsycholog—
ical deficits. The variability of temporal neocortical in-
terictal epileptiform activity during the ECoG, and the
difficulty in distinguishing primary from projected spike
activity in the frontal lobe remain problems for this tech-
nrque.
FIG. 1 2. The hippocampus is detached by an incision along
the fimbria and through the amygdala. (From reference 99,
with permission.)

344 / CHAPTER 15
Amygdalohippocampectomy
With improvement in localizing seizure onset to dis-
crete areas of the temporal lobe in selected patients, Ya-
sargil introduced the transsylvian approach to resect the
mesial basal temporal lobe (120). Selective removal of
these structures using transventricular and transcortical
approaches was previously described by Niemeyer (165).
The goal is selective microscopic removal of the lateral
amygdala, the anterior hippocampus, and the parahip—
pocarnpal gyrus with preservation of the lateral temporal
structures. This procedure is reported to cause less func-
tional deficits with a similar outcome when compared to
standard lobectomies in selected patients (166). The
transsylvian approach is made through an interfascial
pterional craniotomy, placed slightly posteriorly, expos-
ing the anterior third of the superior temporal gyrus. The
inferior sylvian fissure is opened, and the lateral Ml seg-
ment of the middle cerebral artery is followed until the
basal surface of the superior temporal gyrus is reached,
between the origin of the temporo—polar and anterior
temporal arteries. The limen insulae is opened for a dis-
tance of 2 cm, and dissection is carried until the horn of
the ventricle is reached. The amygdala is dissected with a
microrongeur for histologic studies and the uncus is re-
moved subpially; the hippocampus is dissected circum-
ferentially, after identifying the posterior co1n1nunicat—
ing artery, oculomotor nerve, optic tract, and anterior
choroidal artery. The overall mesial resection covers a
length of 4 cm, a width of 1.5 cm, and a depth of 2 cm.
This microsurgical procedure usually follows SEEG anal-
ysis of the patient's typical seizures.
Posterior Hippocampal Resection
Depth electrode recordings have been reported that
suggest that almost 20 percent of complex partial sei-
zures arise from the hippocampus beyond the posterior
limit of standard anterior temporal lobectomies (167).
Surgical access was modified by Spencer to resect docu-
mented epileptogenic posterior hippocampus through a
small resection of the temporal pole (168). The same
technique can be utilized when space—occupying lesions
are posteriorly placed within the hippocampus or hippo-
campal gyrus. Pathological demonstration of neuronal
loss and gliosis in the posterior hippocampal specimen is
correlated with a good surgical outcome.
Other Limited Resections
Selective corticectomies are performed in areas en-
compassing both interictal and ictal activity and may
occasionally involve portions of more than one lobe.
Neocortical resections following subdural grid evalua-
tions are usually performed at the time the subdural grid
is removed. Although this technique allows the bound-
aries of the resection to be determined preoperatively,
results of cortical stimulation can be confirmed with in-
traoperative bipolar stimulation under local anesthesia.
Many centers still perform neocortical resections using
intraoperative functional mapping alone (121). Exci-
sions of limited areas of sensorimotor cortex can be
made with minimal deﬁcits, but dissections must respect
ascending arteries by skeletonizing these structures
(169). Care must also be taken not to extend the resec-
tion beyond the insula or deep into the white matter in
order to preserve long fiber tracts. Speech mapping al-
lows resection of peri—sylvian cortex in patients with evi-
dence of early ictal interference with speech. We prefer
to preserve Broca's area, even with evidence of ictal on-
set involving this region. Due to variability in the size
and location of Wernicke's area, functional mapping
permits more extensive dominant posterior temporal re-
section in some patients. Multiple subpial transections
of essential cortex, such as sensorimotor and language
areas, have been reported to interrupt seizure initiation
without inducing unacceptable neurological deficits
(170), but we have not yet had experience with this tech-
nique. Small resections within the occipital lobe can pre-
serve visual function with excellent control of the sei-
zure. Stereotactic ablations such as amygdalotomy and
Field of Forel—otomy are no longer recommended
(171,172).
Hemisp/ierectomy
The initial technique of cerebral hemispherectomy,
described by Krynauw (173), involves resection of a
complete hemisphere, leaving in place the thalamus, ba-
sal ganglia, and brainstem on the ipsilateral side. After a
large hemicraniotomy and dural opening, distal
branches from the anterior cerebral, middle cerebral,
and posterior cerebral arteries are divided, leaving proxi-
mal vascularization to the basal ganglia intact. The cor-
pus callosum is divided completely, and the lateral ven-
tricle is entered. The caudate nucleus is identified, and a
plane of dissection is carried above the caudate from an-
terior to posterior down the atrium at the temporo—occi—
pital junction. The veins that drain into the sagittal sinus
and into the vein of Galen are taken. Following the lat-
eral ventricle into the temporal horn, the temporal lobe
is dissected in a fashion similar to the en bloc resection.
The insula is also taken. Because of complications ini-
tially described with this technique, including delayed
hemosiderosis and later hemorrhage and death, Ras-
mussen modified the complete hemispherectomy to a
subtotal hemispherectomy, leaving the disconnected
frontal and occipital poles in the surgical cavity
(174,175). The insula may or may not be removed ac-
cording to the intraoperative electrocorticogram. An ad-

ditional modification to prevent delayed bleeding con-
sists of plication of the dura, as described by Adams
(176). Other centers, such as UCLA, prefer to shunt the
surgical cavity into the peritoneal space, decreasing the
fibrinogen and blood products inside the surgical cavity
and preventing the formation of subdural membranes
(177). Multilobar resection may also be appropriate
when large parts of the cortex appear to be abnormal but
some ipsilateral areas can be spared (178).
Corpus Callosotomy
Most centers performing corpus callosotomy divide
the structure in two stages (179). Initially, the anterior
two—thirds is sectioned, including the genu, followed
later by posterior division of the splenium, if seizures
persist. The technique necessitates a vertex frontal crani-
otomy, usually over the nondominant hemisphere, ex-
posing the anterior interhemispheric fissure and preserv-
ing the large draining veins to the sagittal sinus. Vascular
anatomy is best deﬁned presurgically with'a cerebral an-
giogram. Gentle lateral retraction of the frontal lobe al-
lows the identification of the cingulate gyrus and, inferi-
orly, of the pericallosal arteries. With magnification, the
white reﬂection of the corpus callosum can be easily seen
between the two pericallosal arteries. Care must be taken
not to confuse the callosomarginal artery with a pe1‘ical-
losal artery and proceed with the dissection into the cin-
gulate gyrus. Division of the anterior two—thirds of the
corpus callosum is made with an ultrasonic aspirator
(CUSA) or with a small bore microsuction and fine bipo-
lar forceps. The ependyma of the roof of the third ventri-
cle can be identified and should be preserved to avoid a
possible ependymitis. The dissection is carried anteriorly
into the genu of the corpus callosum and stopped once
the rostrum is reached. Division of the anterior commis-
sure, fornix, or massa intermedia of the thalamus, as
originally described by Van Wagenen and Herren (com-
plete commissurotomy) (180), is no longer performed. If
seizures persist, a second stage callosotomy can be done,
extending the section into the splenium of the corpus
callosum.
SPECIAL CONSIDERATIONS FOR
THE DEVELOPING BRAIN
The obvious beneﬁts of early intervention have made
pediatric epilepsy surgery an area of increasing interest
and rapid expansion. The approach to the surgical treat-
ment of intractable partial epilepsy in adults applies in
many respects equally to children with similar partial
epileptic disorders. Nevertheless, some uniquely pediat-
1'ic epileptic syndromes are also potentially treatable by
surgery. Moreover, considerations of brain development
and plasticity add a dimension to pediatric epilepsy sur-
TI-IE EPILEPSIES / 345
gery that is not present with respect to adult patients
(137). In this section will be summarized the major ways
in which the approach to surgical management needs to
be adapted to the developing brain. The types of surgery
most commonly performed also differ: anterior tern-
poral lobectomy for complex partial seizures is the most
common form of epilepsy surgery in adults, whereas ex-
tratemporal excision, multilobar resection, hemispher-
ectomy, and corpus callosum section are the appropriate
treatments in a much higher proportion of pediatric
cases.
Intractability
The amount of time necessary to determine intracta-
bility is typically much shorter in pediatric than adult
surgical candidates. For the latter, it usually takes several
years to have exhausted all appropriate medical trials. In
contrast, there are far fewer antiepileptic drugs available
for use in young children, particularly infants; moreover,
because their seizures are typically much more frequent,
less time is required to determine whether a given change
in management has had any effect.
Certain etiologies of frequent seizures imply intracta-
bility almost by their very nature; for example, congeni-
tal brain malformations (181), Sturge—Weber syndrome
with early—onset seizures (182), or Rasmussen's encepha-
litis (183). Ifthe seizures in such cases do not respond (or
respond only temporarily) to two or three of the most
appropriate antiepileptic drugs, it is extremely unlikely
that they will respond to any medical regimen or will
spontaneously remit. Cases of West syndrome unre-
sponsive to ACTH, prednisone, and/or selected antiepi-
leptic drugs like nitrazepam, are similarly unlikely to un-
dergo spontaneous remission, even though the infantile
spasms will change to some other seizure type as the
child grows (184). In rare cases, the unlikelihood of re-
mission can be determined even as early as the neonatal
period as, for example, with persistently unifocal, cryp-
togenic status epilepticus, which probably begins in utero
and, in our experience, has been uniformly due to focal
cortical dysplasia (87).
Most young children who are potential surgical candi-
dates have many seizures per week or even per day, and
there is little question regarding the designation of in-
tractable. Some children who have only occasional sei-
zures, however, might be considered potential surgical
candidates because of the deleterious effects of rnedica—
tions and interictal electrophysiological disturbances on
their development, particularly when there is a high like-
lihood of later breakthrough of more frequent seizures.
Drug toxicity is typically much more evident in adults
than in children. A child of average intelligence who is
toxic on antiepileptic medication is often mistakenly
considered to be dull (185). In other cases, side effects of

346 CHAPTER 15
medications can produce adverse personality changes
that seriously stress family dynamics and reduce the self-
esteein of the child (186). Thus, even though diu g toxic-
ity per se may be readily reversible, some consequences
of its chronic presence could be permanent. To the ex-
tent that resective surgery could permit the elimination
or significant reduction of medication during these intel-
lectually and emotionally formative years, it might even-
tually be considered even if seizure frequency per se
might not be great enough to suggest a need for surgical
intervention.
Timing of Surgery
Considerations related to development and plasticity
render surgery more urgent in children than in adults,
given surgical candidacy. The extent to which frequent
seizures might damage the developing brain remains
highly controversial; nevertheless, there is considerable
evidence that molding of interneuronal connections is
profoundly inﬂuenced by local electrical activity (187),
interactions with other neurophysiological subsystems
(188), and dynamic interaction with the environment
(189). That repeated brief seizures do not cause neuronal
damage, in the pathologist's sense of hypoxic/ischemic
changes and neuronal loss, therefore in no way implies
that they are not harmful to the developing brain.
Frequent interictal epileptiform discharges might also
underlie the deleterious effects of what Penfield aptly
called noczferous cortex (190). These discharges are
known to cause transient disruption of cortical function-
ing not only at the site of the spike but at surrounding
and distant sites as well, through projected inhibitory
postsynaptic potentials (191) and antidromic "backfir-
ing" (192), both in experimental animals and in humans
(193). In the developing rabbit brain, interictal dis-
charges in the absence of seizures have been shown to
lead to cytoarchitectural changes in spatially distant but
functionally related areas (194). Such mechanisms could
contribute to the gradual intellectual and psychosocial
decline common in children with catastrophic epilepsy
(195), suggesting an argument for performing the sur-
gery as early in life as possible.
The extent to which antiepileptic drug toxicity can ad-
versely affect the developing brain directly, apart from
the secondary psychosocial consequences of their side
effects, has not been thoroughly studied. Although the
literature is conﬂicting, there are a sufficient number of
reports that suggest deleterious effects to warrant con-
cern (196-198) and to constitute a minor additional ino-
tive for favoring a potentially curative procedure over
the chronic administration of multiple, high—dose anti-
epileptic medications.
Although controversies continue over whether the
kindling phenomenon in animals is relevant to humans
(199,200), the risk of secondary epileptogenesis (201) re-
mains a concern for children with frequent recurrent sei-
zures. That this process is potentially reversible is sug-
gested by the fact that seizures and EEG spikes can often
disappear when children with bilateral or multifocal inde-
pendent epileptiform discharges, bilateral independent
ictal onsets, hypsarrhythmia or modified hypsarrhyth-
1nia, or generalized slow spike waves undergo focal resec-
tion or hemispherectomy based on evidence of local-
ized or lateralized abnormalities on brain imaging
studies, EEG telemetry recorded ictal onsets, and/or
ECoG( 1 37).
Experience with naturally occurring brain lesions and
with therapeutic hemispherectomy in humans indicates
that language functions will shift to the right hemisphere
following damage to the left early in life (202,203). Si1ni-
larly, children or adults with hemiplegia from early in-
fancy are typically able to walk quite well and can use the
paretic arm for gross, proximal movements and as a
helper for the normal arm (204,205), in marked contrast
to the dense hemiplegia following massive hemispheric
infarction in adulthood. Consequently, the earlier the
surgical intervention, the less the resultant deficit.
For all these reasons, the dynamic nature of neurode-
velopinent and that of the epileptic process itself intro-
duce a particular urgency in the determination of inedi-
cal intractability among children. There must be a
prudent compromise between letting sufficient time pass
to determine intractability and operating early enough to
maximize developmental potential through brain plastic-
ity. But once it becomes clinically evident that a young
child is suffering from one of the devastating epileptic
syndromes and that cortical resection offers a significant
chance of benefit, the earlier the operation is performed,
the better.
Identification of the Epileptogenic Zone
Some children with seizure disorders presently classi-
fied as secondary generalized epilepsies can benefit
greatly from resective surgery. Although the West and
Lennox—Gastaut syndromes, even those subclassified as
cryptogenic, have traditionally been thought to indicate
diffuse cerebral abnormalities (55), perhaps as many as a
third of the cases are actually due to focal or unilateral
pathology (206-209) and could respond favorably to fo-
cal resection or hemispherectomy (138,210). In such
cases, localization of the epileptogenic region is accom-
plished by the convergence, or at least noncontradiction,
of complementary types of evidence from structural
imaging studies, tests of epileptic excitability, and tests of
cortical dysfunction. Even when the ictal onsets are diffi-
cult to localize or lateralize and the epileptiform dis-
charges have a multifocal or widespread distribution, a
safely resectable lesion can be strongly suggested by dem-

onstration of a substantial focal functional deficit and a
structural lesion. In this instance, intraoperative ECoG
may be helpful for multilobar resections but is superﬂu-
ous if a complete hemispherectomy is planned (211).
Chronic intracranial electrode recordings are reserved
for those cases with lack of correspondence among the
various structural and functional parameters, or in
which the anticipated resection borders on essential
primary cortex, requiring careful functional map-
ping (161).
Indicators of focal cortical dysfunction are important
for two reasons: first, it is very likely that the epilepto—
genic region is anatomically identical to, or approxi-
mates, a zone of markedly dysfunctional cortex; and sec-
ond, the excision of such an area will not introduce a
signiﬁcant new neurological deficit. Because the neuro-
logical examination in young children is much less local-
izing than in adults and large portions of cortex are as yet
clinically silent, it is important to assess cortical function
in as many other ways as possible, including interictal
EEG (with particular attention to nonepileptiform ab-
normalities), sodium thiopental activation, median
nerve somatosensory and visual evoked potentials, intra-
carotid amobarbital injection (Wada test) for older chil-
dren in whom the lateralization of memory and lan-
guage can be tested, and local cerebral metabolic
patterns on interictal FDG—PET scan. If hemispherec—
tomy is contemplated, these tests are also important for
determining the relative functional integrity of the other
hemisphere.
Of all these tests, the most useful in this group of pa-
tients is by far the FDG—PET scan, which can reveal well-
demarcated areas of marked dysfunction, even in the
context of normal CT and MRI studies (87,139,208).
These focal FDG—PET abnormalities have corresponded
closely with areas of dysfunction defined subsequently
by intraoperative electrocorticography (211) and with
focal cortical dysplasia on pathological examination of
resected tissue. FDG—PET and intraoperative electrocor—
ticography are now Used to guide multilobar resections
in small children with catastrophic secondary general-
ized epilepsies, particularly infantile spasms, even when
epileptiform abnormalities are not localizing (208). Sur-
gical resection in these children not only abolishes epilep-
tic seizures, but reverses developmental delay, which is
the most pressing criterion for considering surgical inter-
vention in this situation.
OUTCOME
Complications
A detailed analysis of surgical complications following
diagnostic or therapeutic procedures in major centers
performing epilepsy surgery has been made by Van
Buren (212) and will be brieﬂy reviewed in this section.
THE EPILEPSIES / 347
Complications ofDiagnostic Procedures
Invasive monitoring by stereotactic depth electrode
implantation carries a mortality rate of approximately 1
percent and a morbidity rate of approximately 4 percent
(212). No major complications have yet occurred using
magnetic resonance guidance associated with stereotac—
tic angiography (145). Transient hemiparesis has been
described with cerebral angiography, but the risk of ma-
jor complications, such as permanent neurological defi-
cit or death, is reported to be only 0.1 to 0.3 percent
(213). The use of stereotactic angiography has decreased
the number of hemorrhagic complications of depth elec-
trode implantations in most centers. Infectious compli-
cations of chronic depth electrode recording are reported
to vary between 1 and 5 percent. These consist of cere-
bral abscesses or meningitis and are more likely to occur
with increasing duration of the recording period. The
value of prophylactic antibiotics has not been estab-
lished. Electrodes should be disposable, to prevent any
possibility of transmission of slow virus such as Creutz-
feldt—Jacob disease (214).
Epidural grid recording as described by Goldring and
Gregorie did not produce any mortality in 100 patients
(215). They did report one scalp infection and one case
of aseptic necrosis of the bone ﬂap in this series. Sub-
dural grid implantation for chronic recording can pro-
duce a transient rise in intracranial pressure (ICP), pre-
sumably frorn cerebral edema, in the first 48 hours. We
now use ICP monitoring concomitantly with steroids for
the first three days after electrode implantation. Acute or
delayed hemorrahgic complications occur in 0.5 percent
of cases. Placement of subdural strips is also associated
with hemorrhagic complications in 0.5 percent of cases
(212). Foreign body reaction to the grid has also been
described (212), and we have seen acute granulomatous
meningitis in a few patients of our series. Decreasing
intraoperative manipulation with the subdural grid and
copiously irrigating the subarachnoid space before im-
plantation appear to prevent this reaction.
Complications ofResective Procedures
Localized Cortical Resection
Aseptic meningitis presenting with fever and neck ri-
gidity is reported to occur in approximately 15 percent of
patients who undergo cortical resection (212). Cerebro—
spinal ﬂuid studies show an increase in white blood cells
and protein and a decrease in glucose. Repeated cultures
remain negative. This complication improves without
treatment in 2-3 weeks.
In all series of anterior temporal lobectorny the rnortal—
ity rate is extremely low. Minor side effects are frequent,
however. Most frequent is a superior quadrantanopsia
opposite to the side of surgery. Fortunately, this usually

348 / CHAPTER 15
remains unnoticed by the patient. Complete homony—
mous hemianopsia can occur due either to an optic tract
injury or an infarct of the optic radiations or occipital
cortex following injury to the posterior cerebral
branches. This complication is rare in most series. Tran-
sient oculomotor or trochlear nerve palsy is also de-
scribed following temporal resection and may take a few
weeks to improve completely. Transient or permanent
hemiparesis can be caused by prolonged retraction or
vasospasm of the middle cerebral artery ("manipulation
hemiplegia") or by injury to the anterior choroidal artery
supplying the internal capsule or cerebral peduncle.
Complications from resections of the dominant hemi-
sphere include speech difficulty, dysnomia, and dyspha—
sia. These are, however, transient and occur in approxi-
mately 5 percent of cases. Severe memory deficit has also
been described rarely in all series; at—risk patients may be
identified with the intracarotid amobarbital test,
Extraternporal resections may produce neurological
deficits functionally related to the site of cortical re-
moval. No attempt to describe these in detail will be
made here, but the reader may wish to consult Van
Buren's chapter (212).
Hemispherectomy
A complete hemispherectomy initially carried a high
operative mortality rate, reaching 6.6 percent, and was
also associated with serious complications late in the
postoperative course (174,175). The complications con-
, sisted of delayed superﬁcial cerebral hemosiderosis lead-
ing to subdural membrane formation causing late hemor-
rhagic catastrophes. This was attributed to repeated
minor trauma to the remaining hemisphere moving
freely in the cranial space, or to residual blood products
leading to subdural membrane formation. Modification
of the complete hemispherectomy, as discussed by Ras-
mussen, was intended to decrease the amount of 1nove—
ment within the cranial space (174,175). Adams at-
tempted to decrease the subdural space by plication of
the dura (176), but this can cause a rapid rise in intracra—
nial pressure because of the decreased reabsorption ca-
pacity of the arachnoid villi. Acute hydrocephalus is also
a major complication, attributed to granular ependymi—
tis blocking the ventricular system. Additionally, the ab-
sorption capacity of the remaining hemisphere may be
decreased, creating a degree of nonobstructive hydro-
cephalus. Shunting of the surgical cavity to the perito-
neal space appears to decrease the amount ofhydroceph—
alus and subdural membrane formation by decreasing
the amount of fibrinogen and blood breakdown prod-
ucts (177).
Corpus Callosotomy
Besides surgical complications such as infection or
frontal lobe infarction from venous thrombosis, neuro-
psychological complications following callosotomy are
frequent (140) and will be described only brieﬂy here.
Transient mutism or decrease in speech spontaneity
may occur after an anterior or a complete section of the
corpus callosum. This may be due in part to intraopera—
tive retraction over the supplementary motor area. In
some patients with mixed cerebral dominance, callosot-
omy produced permanent speech and language dysfunc-
tion (142). A posterior section of the corpus callosum
produces a sensory disconnection syndrome that is best
demonstrated by tachitoscopic studies. Postoperative
worsening of seizures in a patient with a frontal focus has
been described (216).
Seizures
Variations in surgical approaches from one center to
another have complicated attempts to make general
statements about results. However, sufficient data have
been accumulated from a large number of centers to
draw some conclusions regarding the efficacy of anterior
temporal lobectomy. In 1975, Jensen reviewed 2,282
published cases of temporal lobectomy and reported an
interseries range of 27.8 to 61.8 percent of patients who
became seizure—free (110). Data shown in Table 1 were
obtained 10 years later from 44 epilepsy surgery centers
(46). The results for anterior temporal lobectomy were
similar to those reported by Jensen, while extratcmporal
resections were somewhat less beneﬁcial. The best re-
sults following extratemporal surgery were obtained with
hemispherectomy and large multilobar resections, al-
though neurological deficits inevitably occur. Corpus
callosum section appears to be largely a palliative, rather
than curative, procedure. As mentioned previously,
there is evidence to suggest that surgical results for ante-
rior temporal lobectomy are better if mesial temporal
structures are routinely removed (26,113). On the other
hand, memory impairment may be more common when
lobectomy includes the hippocampal pes.
Postoperative results with respect to epileptic seizures
comprise the most important category of data for deter-
mining the therapeutic usefulness of presurgical evalua-
tion protocols and operative techniques, yet these results
are the most difficult to define and quantify. Data are
reported inconsistently in the literature. For instance,
patients are usually considered seizurefree even if auras
continue, yet persistent auras suggest that the primaiy
epileptogenic region was not completely removed and
only the spread has been prevented. For analysis of out-
come in terms of the patient's ability to conduct a nor-
mal life, postoperative auras are usually inconsequential;
however, in the context of attempts to understand the
mechanisms of epilepsy and its resolution, this is an irn—
iportant consideration. Also, the term seizurefree does
not necessarily mean free of seizures since surgery be-
cause, from a practical point of view, a patient who has
had a few seizures in the first year or two after surgery

THE EPILEPSIES / 349
TABLE 1. Survey results: outcome with respect to epileptic seizures”
Anterior Extratemporal Corpus callosum
Classification Hemispherectomy temporal lobectomy resection section
Total Patients 88 2,336 825 197
Total Centers 17 40 32 16
Number Seizure-free 68 1 ,296 356 10
Percent (Range) 77.3(0—100) 55.5 (26-80) 43.2(O—73) 5.0 {O—1 3)
Number Improved 16 648 229 140
Percent 18.2 27.7 27.8
Number not Improved 4 392 240 47
Percent (Range) 4.5 (0-33) 16.8(6—29) 29.1 (17-89) 23 9 (10-38
" From reference 46, with permission.
and then becomes seizure—free is just as well—off. Al-
though soine studies have lumped seizure—free and al-
most seizure—free patients together, in most cases there is
a considerable difference between the two in terms of
social rehabilitation.
The outcome classification scheme suggested by the
International League Against Epilepsy is shown in Table
2. The seizure—free and rare seizure categories are rela-
tively straightforward. However, when deciding whether
or not to perform an operation on a particular patient,
the probability of worthwhile improvement rather than
complete cure is usually the determining factor. There-
fore, in order to evaluate the literature on a specific pro-
cedure or the track record of a particular center, it is the
definition of this borderline group that should be most
carefully considered. Unfortunately, criteria for differen-
tiating patients with worthwhile improvement who con-
tinue to have some seizures from those who do not bene-
TABLE 2. Outcome classification"
Class 1 :Seizure-free“
A. Completely seizure—free since surgery
B. Aura only since surgery
C. Some seizures after sugery, but seizure—free for at
least two years
D. Atypical generalized convulsion with antiepileptic drug
withdrawal only
Class 2: Rare seizures (almost seizure—free)
A. Initially seizure—free but has rare seizures now
B. Rare seizures since surgery
C. More than rare seizures after surgery, but rare
seizures for at least two years
D. Nocturnal seizures only, which cause no disability
Class 3: Worthwhile improvement
A. Worthwhile seizure reduction
B. Prolonged seizure—free inten/als amounting to greater
than half the follow—up period, but not less than two
years
Class 4: No worthwhile improvement
A. Significant seizure reduction
B. No appreciable change
C. Seizures worse
“ From reference 46, with permission.
6 Excludes early postoperative seizures (first few weeks).
fit from surgery are virtually impossible to define in a
standardized, quantitative fashion and often must be de-
termined independently for each individual.
Another problem derives from the fact that patients
may change, with respect to seizures, at any time. Since
this appears to be more common during the first few
years, some investigators feel it is necessary to wait five
years after surgery before drawing any conclusions re-
garding surgical results. Our experience, and that of
others (32,46,ll2), suggest that changes occurring after
two years are not much more clinically significant than
those after five, and that two years is an adequate follow-
up time for assessing results. Patients should be cau-
tioned, however, that one or two seizures in the first two
years following surgery do not necessarily mean they will
not ultimately become seizure—free, nor does the absence
of seizures during the first two years guarantee that sei-
zures will never return (Figs. l3 and 14). Because out-
come status can change from year to year, in order to
compare groups of patients with different follow—up pe-
riods it is preferable to use year—by—year outcome data
(Fig. 15).
Outcome statistics for surgical treatment of epilepsy
reﬂect selection philosophy as much as, if not more than. ,
accuracy of selection criteria. If only the best candidates J
for surgery were chosen, most centers would maintain
close to a l00—percent success rate. However, surgery is
often offered to patients whose diagnostic evaluation in-
dicates a higher probability of a poor outcome, because
nothing else can be done and maybe it will help. These
calculated risks probably account for the 10 to 20 per-
cent of patients who do not benefit from surgery in al-
most every series. An important measure of effective-
ness, therefore, would be obtained froin knowledge of
the number of patients denied surgery who might have
benefited from this procedure. Absolute data are i1npossi—
ble to derive, but some information is available to indi-
cate that there is improvement in this area. For instance,
in 1967 only 11 percent of patients evaluated in Fal-
coner's series were selected for surgery (1 1 ), while approx-
imately 80 percent of all patients who undergo the
UCLA inpatient evaluation receive surgery.

FIG. 13. Year—by—year outcome classifications for patients
who were classified as seizure—free for one year (A) and two
years (B) after surgery. Outcome classifications are defined in
Table 2. (From reference 46, with permission.)
Psychosocial Adaptation
Behavioral changes associated with temporal lobe sur-
gery for epilepsy are related to psychosocial factors, as
well as to relief from seizures. It is generally agreed that
personality traits are more likely to improve after success-
ful surgery than are psychoses. Depression during the
first year following surgical treatment has been reported,
but is usually transient (217,218). While long—te1m de-
pression may be no more prominent postoperatively
than preoperatively, the reported 5 percent incidence per
mean five years of follow—up (114) stresses the need for
more intensive studies. The published effects of surgical
intervention on psychoses have been consistent. Surgical
treatment, while helping the epilepsy, does not improve
a chronic psychotic condition, which is usually the ma-
jor handicap for the patient (114). This is not the case for
rare ictal or postictal transient psychoses that usually re-
solve when the epilepsy is cured (219).
FIG. 14. Year—by—year outcome classifications for patients
who were classified as having rare seizures (A) and many
seizures (B) during the first postoperative year. The latter pa-
tients are those who were classified as Class 3 and Class 4.
Outcome classifications are defined in Table 2. (From refer-
ence 46, with permission.)
The extent of control of seizures is a signiﬁcant factor
underlying improvement in social status following surgi-
cal treatment for epilepsy (105). We found that patients
tend to be slightly more dependent upon others two
months after the operation regardless of outcome, appar-
ently due to recovery from the recent surgery (101). But
by one year after surgery, patients whose seizure fre-
quencies are significantly reduced show the expected
gains in social independence when compared to their
preoperative social level. This is reﬂected by the percent-
age of patients who become employed or receive educa-
tional retraining. Similar social changes are not seen in
patients whose seizures are not controlled by surgery.
At one year after surgery, interpersonal relationships
also improve for the seizure—controlled patients. This im-
provement seems to be largely attributable to increased
non—family interactions, apparently associated with
newly developed social independence. The family rela-
tionships of patients are more resistant to change; in
some cases, interpersonal family relationships have even

New Series ———O|d Series
FIG. 1 5. Year—by—year outcome classification for all patients
operated on at UCLA between 1 961 and 1985, divided into
those operated on before 1977 (broken line) and after 1977
(solid line), when the new presurgical evaluation protocol was
introduced. This graph demonstrates that after 1977 the per-
centage of patients who were seizure—free at the end of each
postsurgical year was higher, and the percentage of patients
who were not improved was lower. Outcome classifications
are defined in Table 2. (From reference 46, with permission.)
deteriorated following seizure control. For instance, di-
vorce appears to be more common in patients who have
become seizure—free. In this situation, the marital rela-
tionship apparently has required the patient to maintain
a dependent role (101). In selected cases, family counsel-
ing has proved beneficial.
Postoperative psychosocial adaptation improves in
most patients who experience relief from, or reduction
in, epileptic seizures. Risk factors for apoor psychosocial
outcome include inadequate family support, operation
after the age of 30, and evidence of an addictive personal-
ity (104).
Patients with improved seizure control show higher
scores on intelligence tests as early as one to two months
after surgery, and scores continue to increase for at least
one year. An average 10 point increase in IQ scores in the
first year is of particular significance, since all patients
are maintained during this time on preoperative anti-
convulsant medication levels. Intellectual changes seen
at this time, therefore, cannot be attributed to reduction
of medication levels, but probably reﬂect a general im-
provement in adaptive abilities heretofore depressed by
THE EPILEPSIES / 351
an active epileptic focus. Increases in intellectual scores
were not found postoperatively in patients whose sei-
zures were not controlled, nor in evaluated but un-
operated epileptic patients tested at comparable pe-
riods (101).
Selective memory deﬁcits have been well documented
following surgical excision of either the left or right tem-
poral lobe. Difficulties in learning verbal material, pre-
sented either aurally or visually, have been associated
with the language—dominant temporal lobe. Difficulties
in learning material not easily verbalized have been asso-
ciated with the nondominant, temporal lobe (220,221).
The degree of memory deficit has been related to the
extent of hippocampus removed (107), and to the extent
of intactness of the opposite hippocampus (103). Recent
evidence indicates that these selective learning deﬁcien-
cies occur whether or not the seizures were controlled by
the surgery (101). However, patients whose seizures are
surgically controlled, while demonstrating the selective
memory deficit associated with temporal lobe removal,
may concurrently show an increase in memory skills
normally associated with the contralateral intact tem-
poral lobe (101,222). This phenomenon is undoubtedly
related to the same process responsible for postoperative
increases in intellectual skills.
In Western societies a deficiency in verbal memory,
which is associated with dominant temporal lobe resec-
tion, is usually a greater handicap than a deficit in non-
verbal memory, associated with nondominant temporal
lobe resection. The potential effects of induced memory
deficits on the lifestyles of surgical candidates should be
carefully considered prior to surgery. It is possible that
for certain patients in selected occupations an induced
verbal memory deficit may be more devastating than an
uncontrolled seizure disorder. In our experience, the life-
styles of most patients considered for language—domi-
nant temporal lobe resection have not been heavily de-
pendent upon strong verbal memory skills. This may be
due to the fact that these patients already have subtle
verbal learning deficiencies (107). Nevertheless, selective
memory disturbances are usually enhanced by surgical
excision of the temporal lobe, particularly when seizures
continue, and the consequences of this potential handi-
cap should be considered.
RESEARCH OPPORTUNITIES
Quite apart from the clinical success of surgical ther-
apy for individual epileptic patients, and the value of
data collection for improving the efficacy of these proce-
dures, it is appropriate to discuss the importance of this
work to the more general problem of understanding epi-
lepsy. In the classical tradition of Hughlings Jackson
(223), and Penﬁeld and Jasper (159), much of our knowl-
edge of the functional anatomy of the human brain has

352 / CHAPTER 15
been derived from studies of epileptic patients. Centers
engaged in the surgical treatment of epilepsy have
unique access to correlative behavioral, neuroplrysiologi—
cal, neuroanatomical, neuropathological, and neuro-
chemical information from epileptic patients that pro-
vides an extraordinary opportunity to investigate basic
mechanisms of epileptogenesis and normal brain func-
tion in humans (224). Because most basic research
carried out on epilepsy has employed animal models, the
relationships, if any, between the wide variety of experi-
mental epilepsies (225) and the human epilepsies (226)
are for the most part unknown. The fact that therapeutic
advances have generally come from studies utilizing ex-
perimental animal models has important clinical signiﬁ-
cance. For example, the failure of antiepileptic pharma-
ceutical agents to control certain forms of complex
partial seizures may be directly related to the possibility
that this human disorder involves mechanisms signiﬁ-
cantly different frorn those responsible for seizures in the
animal models used for developing antiepileptic drugs.
A limited amount of data from studies in humans sug-
gests that some aspects of the more popular laboratory
models of epilepsy are common to human epileptogene-
sis. The paroxysmal depolarization shift and afterhyper—
polarization recorded intracellularly from a wide Variety
of experimental epileptic foci produce a burst of neuro-
nal firing followed by inhibition, which correlate with
the EEG spike and slow wave respectively (227). Extra-
cellular recordings from the human epileptic hippocam—
pus have demonstrated similar relationships between
unit firing and EEG waves (228), although the percent-
age of bursting neurons in the human epileptogenic re-
gion appears to be considerably smaller than in experi-
mental neocortical penicillin foci. Golgi stains of cortex
from chronic alumina foci have demonstrated neurons
with shrunken dendrites denuded of dendritic spines
(229). Similar cells have been found in resected temporal
lobe specimens taken from patients with complex partial
seizures (230). Although it is not yet known whether
these anatomically abnormal neurons are responsible for
the epileptic activity, a result of the epileptic activity, or
totally unrelated, their existence has figured prominently
in some theories of epileptogenesis (231,232). Morpho-
logical and electrophysiological data obtained from rats
with kainic acid—induced seizures suggest that loss of
principal neurons in the hilar area ofthe hippocampus
results in sprouting of granule cell mossy fiber axons
back onto their own dendrites, creating recurrent excit-
atory circuits (39). Similar morphological changes have
now been identified in the human epileptogenic lrippo—
campus (37,38).
Differences between human complex partial seizures
and animal models have also been demonstrated by the
evaluation of surgical candidates. The most important
difference is that the majority of patients studied with
implanted depth electrodes do not appear to have a sin-
gle discrete epileptic focus, as is the case with artificially
created experimental lesions, but rather there are many
areas capable of independently initiating interictal, and
at times ictal, epileptiform discharges (233). These mul-
tifocal abnormalities may be the result of functional
changes such as those that occur with secondary epilep-
togenesis (234) or kindling (235), or of structural damage
induced by frequent seizures (34). It is not yet clear
whether the multifocal abnormalities observed in pa-
tients under evaluation for surgery represent features
common to all forms of secondary partial seizure dis-
orders in humans, or whether these findings are peculiar
to those patients whose seizures are medically intractable
and sufficiently severe to be considered for surgical ther-
apy. Evidence frorn primate models, however, suggests
that bilateral foci may be necessary before complex par-
tial seizures can become manifest (236). It is important
to realize that, in patients who are surgical candidates,
the object is to locate and excise the epileptogenic region
most responsible for initiating the patient's habitual sei-
zures, with the understanding that other distant areas of
epileptogenic tissue may very likely remain. This ex-
plains the variable results of surgery for epilepsy: why
many patients are seizure—free but continue to have
auras whereas others are improved although they have
occasional seizures.
Since many experimental animal models of epilepsy
result from interventions that disrupt GABA—mediated
inhibition, similar disinhibition has been suggested to
underlie human epileptogenesis. Morphological stud-
ies, however, suggest there is no preferential loss of
GABA-containing inhibitory interneurons or inhibitory
terminals on principal neurons of sclerotic epileptogenic
human hippocampus (237). Furthermore, electrophysio-
logical studies in human partial epilepsy, as well
as chronic animal models, now suggest that certain
inhibitory mechanisms may be enhanced interictally
(23 8), and in some cases could contribute to the appear-
ance of hypersynchronous ictal epileptiform discharges
(238,239). Since depth electrode recordings have identi-
ﬁed at least two types of ictal onset in human partial
epilepsy, one with low—voltage fast activity and the other
with high—amplitude repetitive spikes (232), the transi-
tion to ictus in human partial epilepsy may involve more
than one mechanism, one perhaps requiring disinhibi-
tion, while the other involves hypersynchronization as a
result of enhanced excitatory and inhibitory mecha-
nisms similar to that proposed for petit mal type ab-
sences (239).
Another important difference between human and ex-
perimental epilepsy is illustrated by the variety of pat-
terns of regional metabolism seen with ictal FDG—PET
in human partial epilepsy (88) compared to the stereo-
typed 2DG autoradiographic patterns seen in animals
with experimental seizures induced by cortical penicillin
(240,241) and amygdaloid kindling (242). Whereas the

preferential spread of ictal discharge from the epileptic
focus in these experimental models appears to be dic-
tated by the site of the primary focus and the technique
involved, propagation of ictal discharge in humans so far
appears to be unique to each individual patient.
Undoubtedly, there are common basic mechanisms of
epileptogenesis underlying both human and experi1nen—
tal seizure disorders. Much of our improved understand-
ing of the fundamental neurobiology of epilepsy, derived
over the past few decades from animal models, may even-
tually lead to new diagnostic and therapeutic approaches
in humans. However, it is of primary importance to
leain which experimental models of epilepsy resemble
which types of human seizure disorders, so that these
models can be used effectively and new models can be
developed where none yet exist. The research opportuni-
ties provided by programs that perform resective surgical
therapy for partial epilepsy should make it possible to
validate and extend basic animal research. The contin-
ued growth of interest in surgical resection as a viable
therapeutic alternative for medically intractable partial
epilepsy has implications beyond the benefit to those few
individual patients who may be selected for this inter-
vention. The data accumulated as a result of these proce-
dures may provide important insights into the basic neu-
ronal mechanisms of the human epilepsies and
eventually lead to new concepts of therapy and preven-
tion applicable to much larger populations of patients.
ACKNOWLEDGMENTS
Original research reported by the authors was sup-
ported in part by grants NS—02808, NS—15654, NS-
20806, and NS—00678 from the National Institutes of
Health, and by contract DE—AC03—76—SF00012 from the
Department of Energy.
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Raven Press, 1987;727.
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quences, Plan for Nationwide Action on Epilepsy, DHEW Publi-
cation No. (NIH) 78-276:1978.
4. Commission on Classification and Terminology of the Interna-
tional League Against Epilepsy. Proposal for revised clinical and
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lepsia 1981;22:489-501.
5. Hauser WA, Kurland LT. The epidemiology of epilepsy in Roch-
ester, Minnesota, 1935 through 1967. Epilepsia 1975;16:l—66.
6. Gastaut H, Gastaut JL, Goncalves e Silva GE, Fernandez-San-
chez GR. Relative frequency of different types of epilepsy: A
study employing the classification of the International League
Against Epilepsy. Epilepsia 1975;16:457-461.
7. Rodin EA. The Prognosis ofPatients with Epilepsy. Springfield,
IL: Charles C Thomas, 1968.
8. Bailey P, Gibbs FA. The surgical treatment of psychomotor epi-
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9. Penfield W, Baldwin M. Temporal lobe seizures and the tech-
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THE EPILEPSIES 353
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Penfield W, Flanigin H. Suigkal tbenp* of temponl tobe sei-
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Falconer MA. Surgical treatment oﬂeapaai tohe epilepsy. V Z
Med] 1967;66:539-544.
Engel] Jr. Approaches to localization ofthe epfcptot, ° . -
In: Engel J Jr, ed. Surgical Treatment of fifcr Cp
York: Raven Press, 1987;75-95.
Bancaud J , Talairach J , Geier S. Scarabin JM. £Zi-
dans les tumeurs cerebrates et I'epilepsie. Pans Bailer —'”'—
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Talairach J , Bancaud J , Szikla G, Bonis A, Geter S. V0kmneC
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Crandall PH, Walter RD, Rand RW. Clinical applications**Ood-
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CHAPTER 16
Spinal Cord Tumors
James E. Rose
History, 359
Incidence, 360
Pathology, 360
Extrarnedullary Tumors, 360
Intrarnedullary Tumors, 360
Natural History, 361
Pathophysiology of Clinical Signs, 361
Speciﬁc Symptoms and Signs, 362
Segmental Sensory Disturbances, 362
Cord Sensory Disturbances, 363
Segmental Motor Disturbances, 363
Cord Motor Disturbances, 363
Regional Diagnosis, 363
Cervical Spine, 363
Thoracic Spine, 364
Lumbosacral Spine, 364
Cauda Equina, 364
Examination of the Spine and Skin, 365
Papilledema,365
Special Diagnostic Tests, 366
Plain X—Rays, 366
HISTORY
Since the time of Hippocrates, surgery of the spine has
been recommended to relieve pressure on the spinal cord
following trauma. It was not until 1814 that Cline did
decornpressive surgery for this condition, however, and
it was McEwen who later reported successful surgery on
a man who had become paraplegic following a spinal
cord injury (1). The compression of the spinal cord was
relieved by removal of bony fragments (2,3).
In 1886 Gowers, who had been familiar with the work
of McEwen, recommended that intraspinal tumors be
removed; he believed that symptoms produced by spinal
tumors were due to long—terrn compression of the spinal
J. E. Rose: Department ofNeurological Surgery, Baylor Col-
lege of Medicine, Houston, Texas 77030.
359
Princi les 0fNeur0surgery,
e(lite( by Robert G. Grossman. Rosenberg © 1991.
Published by Raven Press, Lt(l., New York.
Myelography, 366
Spinal Tap, 367
Spinal Angiography, 368
Computed Tomography, 369
Magnetic Resonance Imaging, 369
Differential Diagnosis, 372
Ruptured Intervertebral Discs, 372
Degenerative Diseases, 372
Syringomyelia, 372
Operative Management, 372
Indications for Surgery, 372
Positioning and Anesthesia, 372
Surgical Technique, 373
Intrarnedullary Tumors, 374
Intradural Extrarnedullary Tumors, 376
Epiderrnoids, Lipornas, and Ependyrnornas of the
Conus Medullaris and Cauda Equina, 376
Postoperative Care and Complications, 377
Postoperative Radiation Therapy, 377
Results, 378
References, 378
cord (4). In 1887 Gowers referred a patient to Sir Victor
Horsley, who performed the first successful removal of
an intraspinal tumor (5). Following this surgery, several
important developments in the history of spinal surgery
evolved, permitting the progressive development ofrnod—
ern spinal surgery. Elsberg reported the first successful
surgical procedure on an intrarnedullary tumor, and
when he published the results of his operations of intra-
rnedullary tumors, he emphasized that an intrarnedul—
lary ependyrnorna incised at a primary operation may be
removed at a second operation when it has extruded
through the incised spinal cord (6). Elsberg's first rnono—
graph was published in 1916 (6) and his last in 1941 (1),
in which he reported the total removal of seven intrarned—
ullary tumors with many ofhis patients showing satisfac-
tory improvement (1,2,6). Dandy introduced air rnyelog—
raphy (7), and in 1921 Sicard and Forestier reported the

360 / CHAPTER 16
use of positive contiast myelography to define spinal le-
sions (8). The next major development in the operative
treatment of spinal cord tumors was the introduction of
the bipolar coagulation forceps by Greenwood in 1940
(9,10). The first—repo1ted total removal of an intramedul—
laiy tumor with complete recoveiy was done in 1941,
and the patient was neurologically normal 13 years later
(11). More recently, the introduction of the operating
microscope, preoperative assessment using computed to-
mography and magnetic resonance imaging, intraopera—
tive use of ultrasound imaging, and the added therapeu-
tic modalities of the Cavitron Ultrasonic Surgical
Aspiiator (CUSA) and laser have further improved the
diagnosis and the treatment of spinal tumors.
INCIDENCE
Primary tumors of the spinal cord and its coverings
are rare. The ratio of primary spinal tumors to primary
brain tumors ranges from 1:7 to 1:10, depending on the
study (12). Spinal tumors can be classified by their rela-
tionship to the dura (extradural or intradural) and to the
spinal cord (extramedullary or intramedullary). Intra-
dural tumors are designated as extramedullary or intra-
medullary. Extradural tumors are largely metastatic and
are rarely primary. When primary, they generally have
both intradural and extradural growth. Approximately
29 percent of intradural tumors are intramedullary, and
approximately 71 percent are extramedullary (13) (Ta-
ble 1). Of the intramedullary tumors, approximately 59
percent are either ependymomas (28 percent) or astrocy—
tomas (31 percent). Of the extramedullary group of tu-
mors, approximately 70 percent are either neurilemmo—
mas or meningiomas. These four classes of intradural
tumors comprise approximately two—thirds of all pri-
mary spinal cord tumors. Of the remaining histologic
types of intramedullary tumors, each comprises less than
2 percent of the total (13). In a large series of 1322 tu-
mors reported by Sloof, Kernohan, and MacCa1ty of the
Mayo Clinic, approximately 29 percent were neurilem-
"al-
TABLE 1 . intradural spinal cord tumors
lntradural tumors Percent
lntramedullary
Ependymomas 8
Astrocytomas 9
Others (each less than 2 percent) 12
Total 29
Extramedullary
Neurilemmoma 27,
Meningioma 231
Sarcoma 10
Others (each less than 2 percent) 11
Total 71
Total 100
8 From reference 13, with permission.
6 Spinal cord tumor statistics vary considerably in different
series.
momas, 25 percent were meningiomas, and 22 percent
were gliomas (12).
PATHOLOGY
Extramedullary Tumors
Neurilemmomas
The most common primary tumor of the spinal cord
arises from the spinal nerve root sheaths (neurilemmo—
mas). In the patients studied at the Mayo Clinic, two-
thirds of these tumors were located intradurally, almost
one—third were entirely extradural, and a smaller group
had both intradural and extradural extension. The larg-
est proportion of neurileininoinas are located in the
lumbar canal. This may be due to the volume of the
roots of the cauda equina (3,12) (Table 2).
Grossly, the neurilemmoma is a firm, encapsulated,
rounded mass. The cut surface is homogeneous with ir-
regular, small, cystic areas within the tumor. Histologi-
cally, the tumor consists of interlacing bands ofcells with
parallel intracellular fibrils and elongated nuclei. These
nuclei may be arranged in parallel rows (palisading).
There may also be areas with lipid—containing cells and
foci of degeneration with microcyst formation. In von
Recl<linghausen's disease (multiple neurofibromatosis),
both spinal and cranial nerves are often involved. Tu-
mors of the central nervous system, including gliomas,
pinealomas, and meningiomas, may also develop.
Meningiomas
Meningiomas comprised 25 percent of the primary
intraspinal tumors in the series reported by Sloof and
colleagues, with approximately 85 percent of these tu-
mors being intradural and extramedullary (12). Of the
remainder, about 50 percent were completely extra-
dural, and the rest were both intradural and extradural
(12). Meningiomas appear grossly as rounded or elon-
gated encapsulated tumors attached to the dura. Micro-
scopically they are comprised of elongated plump cells
with round or oval nuclei. These cells tend to be shorter
than the cells of neurilemmomas, and they are often
arranged in whorls. Calcification is frequently present in
the center of the whorls (psammoma bodies). They are
most commonly found in the thoracic spine and are
more common in women than men (2,12).
Intramedullary Tumors
Astrocytomas
Astrocytomas, the most common intramedullary tu-
mor, are distributed throughout the spinal cord (Table

SPINAL CORD TUMORS / 361
TABLE 2. Distribution of neurilemmomas, meningiomas, and gliomas by vertebral IeveI"
Cervico— Thoraco—
Cervical thoracic Thoracic Iumbar Lumbar
Lesion No. °/c> No. °/c> No. % No. % No. °/c>
Neurilemmoma 88 23.3 3 0.7 125 33.4 9 2.3 152 40.3
Meningioma 43 13.4 10 3.1 261 81.0 2 0.6 6 1.9
Glioma 34 13.9 10 8.2 63 25.7 63 25.7 65 26.5
Total 165 17.5 33 3.5 449 47.6 74 7.8 223 23.6
3 From reference 12, with permission.
2). They occur most frequently in the third through fifth Lipomas
decades of life. Males are affected more often than fe-
males. Their gross appearance is a fusiform swelling of
the spinal cord, which obliterates the subarachnoid and
subdural spaces. Cystic degeneration is present in about
one—third of the cases. Microscopically, most Grade I
astrocytornas consist of an increased number of fibrillary
astrocytes. In Grade II astrocytornas, there is an anaplas-
tic transformation of a number of these cells. Grades III
and IV astrocytomas are characterized by anaplastic
changes and the presence of multiple mitotic ﬁgures.
Ependymomas
Ependymomas may be found throughout the spinal
cord, although they tend to be most frequent in the filum
terminale. More than one—half of these tumors occur in
the fourth and fifth decades of life. Grossly, the tumor
may appear to be encapsulated. The microscopic appear-
ance is that of polygonal cells arranged in a mosaic—like
pattern. A common histologic feature is that of villi corn-
posed of a central core of connective tissue with blood
vessels surrounded by a single layer of ependymal cells.
About 33 percent of these tumors have an increased
number of anaplastic cells.
Epidermoids, Dermoids, and T eratomas
Epidermoids, dermoids, and teratomas are uncorn—
mon tumors of congenital origin. They arise mainly in
the lumbosacral region and are usually intramedullary.
Epidermoid tumors, the most common of these lesions,
are frequently cystic. Histologically, they are composed
of squamous epithelium with intercellular bridges, hya-
line granules, and cornified cells of the inner surface of
the tumor. Dermoid tumors are also cystic and corn-
posed of squamous epithelium; in addition, skin append-
ages such as hair follicles, sebaceous cysts, and sweat
glands may be found. The cyst may often contain hair
and sebum. Teratomas, which are the rarest of these tu-
mors, may be cystic and are composed of multiple tissue
types, including muscle, bone, cartilage, and other tis-
sues of the body foreign to the part from which they
arise.
Lipomas comprise less than 1 percent of tumors aris-
ing frorn the spinal canal. They may be found anywhere
in the spinal canal but are most commonly seen in the
lumbosacral region. Patients may have an associated sub-
cutaneous soft tissue rnass with concomitant radio-
graphic evidence of a bony anomaly at the level of this
lesion. Lipomas ofthe cauda equina are intertwined with
the roots of the cauda equina and may extend into the
substance of the conus of the spinal cord.
Vascular Tumors
Approximately 6 percent of intraspinal tumors are vas-
cular in origin (3). Hemangioblastomas comprise approx-
imately l percent of these tumors. They are most often
located in the cervicothoracic cord. More than one—half
of them are intramedullary. Syringomyelia is present in
two—thirds of the cases, and von Hippel—Lindau's disease
is present in approximately one—third (14).
NATURAL HISTORY
The natural history of spinal tumors is related to their
location in the neuraxis and the histologic cell type. Be-
nign tumors such as neurilemmomas and meningiomas
generally cause progressive neurologic changes over a
long period of time. More rapidly growing lesions in the
spinal cord cause rapid and progressive neurologic dys-
function. Spontaneous hemorrhage is a rare cornplica—
tion of spinal tumors. Primary intraspinal tumors rarely
metastasize outside the neuraxis. However, some pri-
mary tumors, particularly ependymomas, may seed the
entire spinal canal. Although remissions and exacerba-
tions of symptoms and signs, such as those seen in rnulti—
ple sclerosis, occasionally occur with spinal tumors, gen-
erally these tumors cause progressive symptoms.
PATHOPHYSIOLOGY OF CLINICAL SIGNS
The clinical manifestations of spinal tumors are due in
large part to neural and vascular compression. Factors

362 / CHAPTER 16
that determine the clinical picture include the position of
the tumor with respect to the transverse plane of the
spinal cord (dorsal, ventral, lateral, or central); the posi-
tion of the tumor with respect to the longitudinal plane
(cervical, thoracic, lumbar, or sacral); tumor effects on
the blood supply of the spinal cord; the lristologic nature
of the lesion; and the rapidity of compression.
The site of cord compression determines, to a large
extent, the pattern of the neurologic disturbance. Pres-
sure orr the posterior aspect of the cord produces dorsal
column disturbances. Lateral compression produces ipsi—
lateral spastic weakness from impaired function of the
adjacent pyramidal tracts, often associated with contra-
lateral impairment of pain and temperature apprecia-
tion (the Brown—Sequard syndrome). Pressure on the an-
terior aspect of the cord can produce ataxia of the legs
towing to interference with spinocerebellar pathways.
Decreased pain and temperature appreciation in a seg-
mental distribution is a common early sign of centrally
placed irrtrarnedullary tumors that interrupt the decus—
sating spinothalamic pathways. These abnormalities of-
ten occur early irr the course of the disease before other
segmental or lo1rg—tract signs appear. When i1rtrarnedul—
lary tumors invade the anterior horns, lower motor neu-
rons are damaged, producing muscle atrophy, loss of
tone, decreased deep tendon reﬂexes, and muscle fascicu—
lation.
The anatomy of the blood vessels of the spinal cord
(see also Chapter 18) is such that certain regions of the
cord are at particularly high risk when compression of
spinal arteries occurs. One anterior and two posterior
longitudinal spinal arteries, with additional feeding ves-
sels entering the cord along the spinal roots, supply the
upper cervical cord. Arteries entering the spinal cord
along the cervical and lumbar roots are usually derived
from the right and left sides with equal frequency. In the
thoracic region, the majority of the blood supply comes
from the left side. An important vessel supplying the
thoracolumbar cord most commonly accompanies one
of the lower thoracic or upper lumbar roots on the left
side. This vessel, the artery ofAdan1kiewicz, largely sup-
plies the lumbar enlargement. The anatomic arra1rge—
ments are such that the upper thoracic cord at T3—T4 has
the most precarious blood supply. It lies between the two
irrigation systems: the blood supply above comes from
the branches of the subclavian arteries, and below, the
supply comes from the descending aorta. Intrinsic hand-
muscle wasting may be encountered in high extramedul—
lary cervical and foramen magnum tumors, which are
situated at levels higher than the segment innervating the
hand muscles. This false localizing sign has been attrib-
uted to ischemia of the anterior horn cells by con1pres—
sion of the anterior spinal artery or an important radicu-
lar artery. In a similar mamrer, pressure on the artery of
Adamkiewicz or other large radicular arteries may give
rise to signs of a cord lesion at a segment distant from the
actual lesion.
Within the substance of the cord, blood is distributed
by way of a superficial and a deep system. The superficial
network is made up ofbranches ofthe anterior and poste-
rior spinal arteries, which pass transversely around the
spinal cord. The deep circulation of the cord arises from
the sulcal arteries. These branches come from the ante-
rior spinal artery, located in the anterior sulcus of the
cord, pass into the cord through the ventral median sul-
cus, and turn to either side to supply one—half of the
central core. Their territory includes the anterior and
central part of the gray matter and the deeper parts of the
long tracts, including the pyramidal fibers. The distal
portion of the posterior horn and a varying extent of the
posterior columns are supplied by penetrating branches
of the posterior spinal artery. Therefore, pressure on the
anterior spinal artery may play a part in producing py-
ramidal damage arrd in evoking lower n1otor—1reuro1r
damage. This mechanism is thought to be responsible for
the myelopathy of severe cervical spondylosis, where
pathologic examination has revealed a distribution of
cord degeneration compatible with an ischemic lesion.
The consistency of a tumor mass is probably some-
what important irr determining the severity and rapidity
of clinical deterioration. A firm mass such as a disc pro-
trusion or fibrous meningioma probably produces a
more pronounced neurologic deficit more rapidly than a
soft tumor or a cyst of the same size. However, the rapid-
ity of tumor growth is probably a more important factor
in determining the rate of neurologic deterioration.
Compression that develops over the course of years can
deform the cord until it is almost ribbon—thin, but it can
still retain function to a remarkable degree.
SPECIFIC SYMPTOMS AND SIGNS
The symptoms of a spinal cord tumor can be thought
of as originating from dysfunction in the segments di-
rectly involved and from dysfunction of the spinal cord
(below the level of the lesion) that has been isolated from
higher levels by the segmental lesion.
Segmental Sensory Disturbances
The most common symptom of spinal cord compres-
sion is pairr, and it is unusual for a patient with a corn-
pressive cord lesion to be free of pain. There are several
types ofpain that are experienced by patients with spinal
cord tumors. Pain of spinal root origin is described by
patients as having a radiating, stabbing quality. The dis-
tribution of the pain conforms to the particular spinal
nerve root involved. The pain may be increased by
coughing, straining, and changes in the position of the
spine. Patients with spinal tumors may also complain of
a qualitatively different type ofpain that is more co1rtinu—
ous and less paroxysmal, often described as aching, dull,
and occasionally burning. This type of pain, which is

usually not inﬂuenced by straining or spinal movement,
is often called "central pain." It has been thought of as
analogous to the spontaneous pain of thalamic lesions
(15). A third type of pain that may occur is paresthetic
pain, or electric shock—like sensations—the so—called
"Lhermitte's phenomenon"—which are provoked by
neck ﬂexion and extension and radiate down the spine
into the arms and legs. A fourth type ofpain is described
as being in the vertebral column itself. Palpation, and
particularly percussion of the spinous process of the af-
fected segment, will evoke the pain.
Cord Sensory Disturbances
The sensory disturbances that develop depend upon
the degree to which various ascending fibers are affected.
Compression of the dorsal columns usually produces
impairment of light touch, joint and position sense, vi-
bratory sense, two—point discrimination, and stereogno—
sis. Compression of fibers of the anterolateral columns
produces impairment of pain and temperature sensibil-
ity. If dorsal column sensation is not impaired, light
touch may be present in the area of loss of pain and
temperature sensation, producing a "dissociated sensory
loss." As lesions grow, they may first impair only periph-
eral fibers in tracts that are being compressed, leading to
the finding of sensory loss in a level lower than the spinal
segment level of the lesion. As the lesion grows, the level
of sensory loss will ascend. When testing for a sensory
level starting from caudal dermatomes and proceeding
rostrally, the examiner may pass from a zone of analge-
sia, through a zone of hypalgesia, and through an area of
hyperalgesia to the zone of normal sensation. This find-
ing is useful in localizing the particular segment of the
lesion.
Segmental Motor Disturbances
Despite the severity of pain that may develop early in
the course of root compression, motor weakness caused
by root compression is a late development because most
muscles receive overlapping innervation. Examination
of the weak muscles will identify the root affected. Ex-
tension of the compression to the anterior horn will ac-
centuate the weakness. The weakness has the character-
istics of a lower motor—neuron lesion, with a loss of
muscle tone, wasting, fasciculations, and depression of
deep tendon reﬂexes. With mixed upper and lower mo-
tor—neuron lesions, the loss of the deep tendon reﬂex and
the presence of muscle fasciculations are signs that the
lower motor neurons are involved, thus indicating the
level of segmental damage. When root pain and sensory
loss are slight, the signs of lower motor—neuron involve-
ment provide the best localization of the longitudinal
level of the lesion. Examination usually reveals abnor-
malities if the lesion involves the cervical or the lumbo—
SPINAL CORD TUMORS / 363
sacral enlargement. On the other hand, segmental motor
disturbances are quite difficult to detect with lesions
above C-5 and between T—l and L— 1. When compression
involves the second and third sacral segments or nerve
roots, micturition is affected, with paralysis of bladder
contractions, bladder distention, and concomitant re-
tention of urine with overﬂow incontinence. Sexual dys-
function may also occur.
Cord Motor Disturbances
Cord motor disturbances occur caudal to the lesion as
a consequence of the interruption of descending motor
pathways, and they reﬂect the activity of a partially iso-
lated cord. The legs are usually involved first. Stiffness,
with an inability to perform rapid movements, is often
more disabling than weakness, which develops more
slowly. The patient may develop difficulty climbing
stairs and ataxia. Micturition is usually affected when
there is bilateral anterolateral tract involvement.
REGIONAL DIAGNOSIS
Cervical Spine
In tumors of the foramen magnum, the upper cervical
segments may be involved. Pain is usually present in the
nape of the neck and occipital region and is aggravated“
by movement of the head. This may cause the patient to
hold the head stifﬂy, resisting movement. Muscle wast-
ing of the suboccipital muscles is not apparent, although
unilateral weakness of shoulder elevation may be seen.
Involvement of the C-4 segment may affect the phrenic
nerve. However, only bilateral phrenic paralysis is
usually detected clinically. Fluoroscopy of the dia-
phragm may be required to demonstrate unilateral paral-
ysis. Impairment of sensation in the trigeminal area may
be encountered in high cervical tumors owing to involve-
ment of the descending spinal root of the fifth nerve.
Pain, which may mimic trigeminal neuralgia, has been
reported in high cervical lesions, but the etiology is un-
clear (15). Tenderness of the spinous or transverse pro-
cesses of the neck may localize the tumor. The sensory
level to pinprick in high cervical lesions may be detected
posteriorly, behind the occiput, and anteriorly, along the
margin of the mandible at the junction of the second
cervical dermatome and the trigeminal nerve. LOW€1‘I€V-
els run around the neck at the collar level. The lower
border of the C-4 dermatome passes across the acromion
process and then anteriorly over the chest to the second
intercostal space, where it is adjacent to the second tho-
racic derrnatorne. In early high cervical tumors, spastic
weakness may affect the legs only, with involvement of
the arms following later. All deep tendon jerks are likely
to be exaggerated. Later, the clinical picture of spastic
quadraparesis evolves, providing the lesion does not ex-

364 / CHAPTER 16
tend too far caudally, where involvement of the C-5 and
C-6 segments would abolish the biceps jerks.
Tumors of the cervical enlargement usually provide
conspicuous localizing symptoms, not only because the
cervical enlargement occupies a large area within the spi-
nal canal, but also because the function of the upper
limb is highly organized. Radicular pain is readily recog-
nized, and its anatomic location is easily identified. Ifthe
patient traces sensory symptoms to the digits, localiza-
tion is simplified by the fact that the index, middle, ring,
and little ﬁngers commonly receive their major supply
from the C-6, C-7, C-8, and T-l nerves, respectively.
Muscle weakness is restricted to a pattern determined by
root distribution. This is in contradistinction to spastic
weakness, which affects the limb distally more than
proxirnally and causes little or no wasting. Although
muscles receive overlapping innervation, usually one
root is dominant for each muscle. This provides excel-
lent clues for localization. For example, the deltoid re-
ceives the C-5 nerve; biceps, C-6; triceps, extensors ofthe
wrist, and extensors of the fingers, C-7; ﬂexors of the
wrist and ﬁngers, C-8; adductors and short ﬂexors of the
thumb, C-8; and small intrinsic muscles of the hand, T-l
(Table 3). Reﬂex abnormalities are important, with the
appropriate reﬂex decreased, depending on the segment
involved. Weakness and wasting of the intrinsic muscles
of the hand may occur as a result of pressure on the cord
at a higher level, as earlier mentioned, and are thought to
be a remote effect on the anterior horn cells. Horner's
syndrome, due to interruption of the cervical sympa-
thetic outﬂow, may be observed from tumors at the cer-
vicothoracic junction. The cause may be an intra1nedul-
lary lesion, affecting the anterior roots of spinal nerves
T-l and T-2, or an extraspinal extension of a tumor
causing damage to the stellate ganglion or the rami corn-
rnunicantes at this level.
Thoracic Spine
Pain, whether of root, central, or vertebral body ori-
gin, is an especially important symptom with thoracic
TABLE 3. Testing of cord segments
Segment Muscles
C2 Extensors of neck
C3, 4 Trapezius, diaphragm
C5 Deltoid, rhomboids, infraspinatus
C6 Biceps, brachioradialis
C7 Triceps, extensor carpi ulnaris,
extensor digitorum
C8 Flexor carpi ulnaris
C8 to T1 Intrinsic hand muscles
L2,3 lliopsoas, adductors of thigh
L4 Quadriceps
L5 Tibialis anterior, extensor hallucis
longus
S1 Gastrocnemius
S2 Intrinsic foot muscles
lesions because it may be the only disability seen until
the development of paraparesis. Focal wasting and
weakness cannot be detected readily in the intercostal
muscles. Atrophic weakness of the abdominal muscles, if
it occurs, is usually late; typically, the affected area
bulges when the abdominal wall is voluntarily con-
tracted. Weakness of the lower abdominal muscles, espe-
cially apparent when the patient tries to rise from the
recumbent position, may be detected by a shift in the
relative position of the umbilicus: the umbilicus is pulled
upward toward the side of the stronger muscles, the so-
called "Beevor's sign." Sensory loss is more easily de-
monstrable on the trunk than on the limbs, owing to the
regular, band-like arrangement of the dermatomes.
which facilitates testing. As previously mentioned, the
C-4 dermatome is adjacent to the T-2 dermatome over
the front of the chest, with the dermatomes of T-2 and
T-3 sending projections into the axilla. The T-l der1na-
tome appears at the end of the elbow on its medial aspect
and supplies the medial border of the forearm and hand,
including the little finger and adjacent border of the ring
finger. The nipples lie within the T-4 dermatome, and
the umbilicus within the T-10 dermatome.
Lumbosacral Spine
In addition to pain of radicular distribution, pain in
the back itself may be quite severe. This may be due to
the frequency of large tumors in the lumbar canal, which
expand the canal. The distribution of the dermatomes
down the leg is such that L-l lies just below the inguinal
ligament. L-3 lies in front of the knee, and L-5 covers
most of the dorsum of the foot except the lateral border,
which is served by the S-l nerve. The saddle area and
perineum are supplied by the lower sacral nerves, with
S-2 supplying a narrow band of varying width down the
back of the thigh and the calf. The muscles moving the
hip joint receive a rather broad innervation, with the
ﬂexor muscles supplied by the upper lumbar segments
and the extensors receiving innervation from the upper
sacral roots. The L-4 nerve is particularly important to
quadriceps function; its impairment will abolish the
knee jerk. The L-4 nerve is also responsible for inversion
of the foot, and L-5 is responsible for eversion. Standing
on tiptoes and plantar ﬂexion of the toes, foot, and ankle
require an intact S-1 nerve supply, with the ankle jerk
being abolished by a S-l lesion. The hamstrings also de-
pend heavily on the S-l nerve. The effects of nerve le-
sions on pelvic organs have previously been described.
Cauda Equina
Compression of the cauda equina may be difficult to
localize because the lesion lies below the termination of
the spinal cord. The clinical picture is one ofroot involve-
ment; consequently, weakness is of the lower motor-

neuron type. Flaccidity, atrophy, fasciculation, and loss
of deep tendon reﬂexes are usually present. The plantar
response is lost if the sensory deficit includes S-1 or ifthe
dorsiﬂexors and extensors of the ankle are too weak to
cause movement. Some lesions of the cauda equina arise
in the periphery of the nerve roots. For example, a neuri-
lemmoma of the L—3 nerve sheath may cause pain and
sensory loss restricted to one limb or involving only the
adjacent nerve roots. Other tumors may involve all of
the nerve roots, such as seen with an ependymoma, one
of the most common tumors in this region. Cauda
equina lesions usually affect roots bilaterally from the
outset. The more centrally located nerves are usually in-
volved first. Radicular pain and pain in the lumbar spine
are usually prominent features of cauda equina lesions
although an ependymoma may reach a large size before
causing significant symptoms, whereas a much smaller
neurilemmoma may give very severe pain. Cauda
equina tumors may extend rostrally, resulting in pres-
sure on the conus medullaris. Some tumors arise from
the conus medullaris, and in these cases, disturbance of
bladder control may be evident early. The dysfunction is
usually that of a paralyzed detrusor of the lower motor-
neuron type. This pattern ofincontinence arises whether
the lesion is located primarily in the conus or cauda.
The sequence of neurologic symptoms may provide
clues as to the origin of the tumor. Conus lesions involv-
ing the S-2 to S-4 segments bilaterally and arising in the
central area of the canal will usually affect micturition
early, but lesions arising in the periphery of the cauda
equina affect micturition later or not at all. Localization
at this level may be difficult owing to the length of the
nerve roots between their attachment to the lumbosacral
enlargement and their departure from the spinal canal.
Therefore, L—3 radicular pain may be due to a lesion of
that root under the third lumbar lamina, where it may
later expand to compress the cauda equina. The pain,
however, might equally be due to a lesion on the root at
or very near to the L—3 spinal segment beneath the
twelfth thoracic lamina, where there may be compres-
sion of the distal spinal cord. Cutaneous sensory loss
from centrally located cauda equina lesions is usually
typical. It is bilateral but not precisely symmetrical, may
show patches of escape, and usually conforms to the so-
called "saddle area" of the buttocks, perineum, and pos-
terior aspect of the thigh, perhaps extending down over
the calf. It is worth noting that, although the penis and
scrotum derive their cutaneous supply from the S-2 and
S-3 nerves and consequently are involved in the area of
sensory loss, the adjacent groin is not.
Localization ofthe level ofthe tumor by clinical meth-
ods provides an answer in terms of cord segments in-
volved. This must be translated into vertebral levels in
order for the surgeon to plan the incision and extent of
bone removal. In the upper cervical region, cord seg-
ments and vertebral levels are numerically similar for
practical purposes, but at lower levels there is an increas-
365
ing discrepancy. The lower cervical segments lie oppo-
site one vertebra higher, and the upper nine thoracic seg-
ments two vertebrae higher. Lower segments are situated
at increased intervals above the vertebrae of the same
number, so that the L—l cord segment is opposite the
T— 10 vertebral body and the sacral segments are opposite
the L—l vertebra. Identification of the spinous process by
palpation and counting is often difficult. Therefore, to
improve accuracy of localization for the surgeon, it is
usual for the radiologist to indicate, with an indelible
mark on the skin of the back, the level of the myelo—
graphic abnormality at the time of examination.
EXAMINATION OF THE SPINE AND SKIN
Careful examination of the whole spine may uncover
clues to the localization of pathology. A short neck, ab-
normal position of the head, or excessive or restricted
mobility of the neck may occur in congenital malforma-
tions and acquired deformities that compress the spinal
cord at the level of the foramen magnum or atlantoaxial
junction. Conditions such as basilarimpression, Arnold-
Chiari malformation, and atlantoaxial subluxation are
but a few conditions to consider in this area. Tenderness
on percussion of one particular spinous process is of use-
ful localizing value but has no special pathologic signifi-
cance. Abnormal curves and restricted movement from
muscle spasms have been mentioned. Spine films may
demonstrate spina bifida occulta, which may have no
significance but raises the likelihood of an intraspinal
dermoid, cyst, or lipomatous mass. The presence of an
intraspinal epidermoid should be considered if a congeni-
tal sinus or midline dimple scar is discovered. Although
these scars may occur at any location, they are more
common in the lumbosacral region. Careful examina-
tion of the skin may show evidence of "cafe au lait"
pigmentation or the subcutaneous nodules seen in von
Recklinghausen's neurofibromatosis. An angiomatous
nevus, which may accompany an intraspinal vascular
tumor or malformation, may likewise be detected from a
careful examination of the skin.
PAPILLEDEMA
Papilledema may occasionally be observed in a pa-
tient with a spinal cord tumor. This condition usually
occurs without intracranial cause and was noted in 1901
by Taylor and Collier to occur with a variety of spinal
lesions. In each instance, the lesion was found to be in
the rostral canal, above the level of T—3 (15). The mecha-
nism is unknown and is not necessarily related to the
very high protein content of the CSF often found with
these tumors, which may disturb the physical properties
of the ﬂuid and thereby interfere with CSF absorption. It
may result from recurrent spinal subarachnoid bleeding,
for example, as in association with an ependymoma.

SGEECJACEDIRTEROSEIC TESTS
The special tests for diagnosis of spinal cord tumors
are plain x—rays of the spine, myelography, spinal tap,
spinal angiography, computed tomography, and 1nag—
netic resonance imaging.
Plain X-Rays
Plain x—rays ofthe spine are useful in the diagnosis and
management of spinal cord tumors. Radiologic abnor-
malities may reveal deformities and malformations asso-
ciated with spinal cord tumors. Skeletal abnormalities
seen with von Recklinghausen's disease include scallop-
ing of the vertebral bodies, scoliosis, and enlargement of
the neural foramen, suggesting the presence of neurofi—
brornas. Congenital malformations such as spina biﬁda,
hemivertebra, and midline bone spurs (diaste1natornye—
lia) may alert the physician to the presence of possible
associated developmental tumors such as lipomas or
dermoids. Syringomyelic lesions are often associated
with skull—base abnormalities, such as platybasia, basilar
invagination, or other skeletal lesions associated with
Arnold—Chiari malformations. Diseases that arise pri-
marily frorn the bone or intervertebral discs may also be
detected. The more common lesions affecting bone and
causing spinal cord compression include destruction of
.the bone by metastatic tumors (primarily metastatic car-
cinoma of the prostate, lung, or breast), Hodgkin's dis-
ease, lymphosarcoma, and other less common tumors,
such as aneurysmal bone cysts, angiomas, osteoid os-
teorna, or osteoblastoma. Spinal cord compression from
diseases affecting the disc space, such as a calciﬁed pro-
truded intervertebral disc or epidural abscess associated
with discitis and concomitant osteornyelitis, may be de-
tected on plain x—rays. Perhaps one of the most effective
uses of the plain x—rays is to show the secondary effects of
a spinal cord lesion on the bony vertebrae. A common
observation is the enlargement of the intervertebral fora-
men from a neurofibroma (Fig. 1) or neurilemmoma. In
the thoracic area these intraspinal lesions may extend
into the thoracic cavity and cause concomitant erosion
of the ribs. An increase in intraspinal pres sure within the
canal may cause erosion of adjacent bone with destruc-
tion of the cortical layer of the medial pedicles or an
apparent widening of the transverse diameter of the spi-
nal canal. Although widening of the spinal canal may be
seen in the presence of congenital malformations, exces-
sive widening of the intcrpcdicular distance in conjunc-
tion with appropriate clinical findings is most suggestive
of an intraspinal neoplasm. The posterior surface of the
vertebral body may be hollowed by the pulsating pres-
sure of the intraspinal mass. These cavities are referred to
as "scalloping" and, when present, often preserve the
integrity of the intervertebral disc and the upper and
FIG. 1 . Enlargement of te neural foramen (arrow) by multi-
ple neurofibromas in a 42-year-old man with von Reckling—
hausen's disease.
lower surfaces of the adjacent bodies. The laminal arches
and the spinous processes may also become thin; when
observed, this condition should alert the surgeon to exer-
cise gentleness in dissection to prevent undue pressure
that could result in fracture of this very tenuous bone
protecting the spinal canal.
Myelography
Myelography is extremely useful in evaluating intra-
spinal neoplasms. An iodine—containing contrast 1nate—
rial is injected via lumbar puncture, usually in the lu1n—
bar subarachnoid space, and, by tilting the table,
contrast is encouraged to ﬂow rostrally until the appro-
priate pathology is detected. If a complete block is sus-
pected, and especially if the ﬂuid is darkly colored after
lumbar puncture, suggesting a high protein content, only
1 or 2 cc of contrast is injected. If there is a total block,
this will show the site of the caudal margin of the block.
In cases of total block it is necessary to introduce con-
trast frorn above, either by making a lateral Cl—2 punc-
ture or by introducing the needle, usually a firm 18-
gauge spinal needle, into the foramen magnum with the
head ﬂexed. The technique of this varies, but in general,
one should palpate the spinous process of C-2 and, after
making a skin weal of local anesthesia, introduce the
needle at this level at an angle of 45 degrees superiorly
until the occipital bone is encountered. The needle is

then gently "walked" inferiorly down the occipital bone
until the foramen magnum area is encountered. Once
the needle is introduced into the canal, which is usually
signaled by a slight "popping" sensation, the stylet is
withdrawn and CSF is allowed to ﬂow. After contrast
material is introduced, the needle is withdrawn and the
rostral extent of the lesion is identified. Contrast mate-
rial injected is usually not withdrawn because this may
cause differential pressure changes, resulting in caudal
shifts of the spinal cord and deterioration in the patient's
neurologic status.
From the characteristic deformity produced by the
opaque column, it is usually possible to determine
whether the lesion is extradural or intradural. An extra-
dural lesion usually creates a senated or paintb1ush—like
margin characterized by a transverse filling defect. The
lateral portion of the contrast column may be displaced
either transversely or in an anteroposterior direction, de-
pending upon the site of the tumor. The two intradural
lesions (extramedullary and intramedullary) may be like-
wise defined by myelography. Most intradural extramed-
ullary tumors produce a rounded filling defect with a
characteristic intradural convexity at the caudal end
(Fig. 2). Lateral views of the spine show the anteroposte-
rior relationship of the cord, and anteroposterior views
allow the cord shadow to be identified and the lateral
displacement appreciated. At the time of the spinal
SPINAL CORD TUMORS / 367
puncture, a small amount of fluid may be taken for analy-
sis of protein and cells prior to insertion of the contrast
material. The Queckenstedt maneuver is usually of min-
imal value and is not routinely recommended. Rarely,
extramedullary lesions placed ventrally cause splaying
and flattening of the cord shadow, thereby mimicking
widening of the spinal cord like intramedullary lesions.
Lateral myelogiaphic views, however, Will reveal the true
nature of this lesion. This "splaying" phenomenon is
more commonly seen with centrally bulging discs or
with ventral osleophytes in patients with cervical spon-
dylosis. True intramedullary lesions show a diffuse, fusi-
form enlargement of the cord shadow (Fig. 3). This cord
widening is seen in both the transverse and anteroposte-
rior views of the spine. Occasionally, enlarged vessels in
the subarachnoid space may be visualized as serpentine
filling defects, which may be confused with abnormal
vessels seen in angiomatous malformations. Angiogra—
phy is occasionally required to make the definitive dis-
tinction.
Spinal Tap
A spinal puncture may be done for diagnostic pur-
poses. The high protein values may produce xanthochro—
mic ﬂuid, which may clot on standing. Protein values of
FIG. 2. (A) Myelographic defect pro-
duced by a ventrally located intradural
extramedullary meningioma. Anteropos-
terior myelogram of the thoracic spine
shows a localized, rounded lesion at the
level of T-3 (arrow). (B) Lateral myelo-
gram shows the ventral location of the
tumor (arrow).

368 / CHAPTER 16
FIG. 3. Anteroposterior myelogram of an intramedullary tu-
mor of the cen/ical cord. There is a diffuse fusiform enlarge-
ment of the cord.
60 to 200 mg/ 100 cc are suggestive of a block. The high
protein levels may be due to a reaction of the subarach—
noid space to the tumor or possibly to secretion of pro-
tein by the tumor (particularly common in neurilemmo—
mas). Cytologic analysis of the ﬂuid may yield additional
information. In general, however, once a spinal cord tu-
mor is suspected, lumbar puncture for diagnostic rea-
sons should not be done. A simple spinal puncture, or
even myelography, may be followed by rapid worsening
of the patient's neurologic condition. This will generally
require an emergency surgical decompression. This re-
sponse usually occurs in the presence of a complete
block and is believed to represent a change in the hemo-
dynamics; it is probably due to reducing the pressure
below the lesion, which causes displacement of the cord
downward with concomitant neurologic deterioration.
Spinal Angiography
Spinal angiography is indicated for suspected vascular
lesions. The catheter tip is so constructed that the tip of
the lumen may be placed near the orifice of the feeding
artery. This is valuable in identifying the feeding vessels
to the tumor and may be used therapeutically to ernbo—
li/e the malformation. It may therefore prove to be a
valuable adjunct in the management of these lesions.
The role of spinal angiography in the diagnosis of spi-
nal cord tumors is becoming less necessary. It is not par-
FIG. 4. (A, B) Anteroposterior and lateral views of a spinal angiogram in a 49-year-old man with an upper
cen/ical hemangioblastoma. Note the absence of early draining veins and the tumor blush, persisting into
the capillary phase, which help distinguish this vascular tumor from a vascular malformation.

ticularly helpful in evaluating spinal cord tumors, with
the exception of the hemangioblastomas and arteriove—
nous malformations. Although the differentiation can be
confusing, the vascular malformations usually have an
early draining vein, whereas the intramedullary heman—
gioblastomas usually have no early draining veins but
have a persistent tumorblush that persists into the capil-
lary phase (Fig. 4).
Computed Tomography
Computed tomography (CT) of the spine is very valu-
able in diagnosing and localizing intraspinal tumors, par-
ticularly in cases that have an associated cystic compo-
nent. The accuracy in diagnosing these cystic cavities is
improved by the injection of a small amount of water-
soluble contrast material. One may see, especially on de-
layed scans of the area, the concentration of the contrast
material within the cystic cavity itself. The mechanism
by which the contrast material enters the cavity is not
known. Additionally, sagittal reconstructions of the spi-
nal canal following the intrathecal administration of
contrast material give valuable information as to the
SPINAL CORD TUMORS 369
size, location, and extent of the intraspinal mass—infor—
mation that may be far more accurate than the informa-
tion obtained with conventional myelography (Fig. 5).
Magnetic Resonance Imaging
Tumors of the spinal cord, especially intramedullary
tumors, are seen very well with magnetic resonance
imaging (MRI). The tumor usually appears as a nonho—
mogeneous area of increased or decreased signal relative
to the adjacent spinal cord. In general, the T,—weighted
pulse sequences demonstrate the anatomic definition of
the spinal cord margin and of the dura. On T2—weighted
images, the spinal ﬂuid becomes bright, and spinal cord
and subarachnoid lesions may not be clearly distinguish-
able (16). In intramedullary spinal cord tumors, the spi-
nal cord is widened, and this is seen well on T, —weighted
images. There is prolongation of the T, and T2 relaxation
times. In T,—weighted images, the lesions demonstrate
low signal intensity and frequently appear darker than
the spinal cord; in T2 —weighted images, however, the le-
sions demonstrate a high signal intensity and appear
much brighter than the spinal cord (16). When one sees
high signal intensity on a T,—weighted image with de-
FIG. 5. This 39-year-old woman presented with severe back pain and right teg pain. (A) Myelography
disclosed a high—grade block at L—4. (B) CT scan with water—soluble contrast material further delineated
the extent and location of this intradural intramedullary tumor, which was shown at surgery to be an
ependymoma. Bar is 5 cm.

70 / CHAPTER 16
HG 6 (A) Longitudinal view of a tumor of the conus medullaris with a histologic diagnosis of teratoma;
(Bj axial view Lesions with regions of high signal intensity on T,—weighted images and lower intensity
signals on T2—weighted images are suggestive of fatty tumors such as Iipomas or teratomas. This lesion
contained hair, mature adipose tissue, squamous epithelium, skin appendages, and skeletal muscle. Bar
in Aand B is5cm.
creasing signal intensity on the T2—weighted images, one
1nust be suspicious of fatty lesions such as lipomas, der-
moids, epidermoids, or teratomas (Fig. 6).
The MRI scan enables one not only to determine the
solid areas of abnormalities but also to differentiate be-
tween solid and cystic tissue within these areas. Unfortu-
nately, one cannot tell the difference between benign
and tumor cysts at all times. However, the relationship
of the cystic area to the tumor is helpful in determining
the etiology of the lesion and in planning the surgical
approach to these tumors (Fig. 7). In addition to obtain-
ing both Tl— and T2—weighted images, the use of g adolin—
FIG. 7. (A, B) This 37—year—old man with a history of progressive quadraparesis was found at surgery to
have an intramedullary ependymoma. Note the associated syrinx. Preoperative knowledge of the loca-
tion of the syrinx enabled the surgeon to establish an early cleavage plane, and a total removal was
aooomplished. Bar for A is 5 cm.

SPINAL CORD TUMORS 371
FIG. 8. (A) Pregadolinium MRI; (B) postgadolinium MRI. The post-gadolinium contrast enhancement of
this spinal tumor clearly demonstrates the rostral and caudal extent of the neoplasm. A gross total
excision of this tumor was accomplished.
ium greatly enhances the demarcation between edema-
tous spinal cord and neoplasm (Fig. 8). Benign cysts
usually have smooth regular margins, but cysts asso-
ciated with tumors are Very irregular and may be asso-
ciated with increased signal intensity from the adjacent
tumor. Calcifications in tumors are poorly seen in MRI
FIG. 9. A 47-year-old woman with a foramen magnum men-
ingioma. The appearances of meningiomas are inconsistent.
They have a tendency to have relaxation times close to those
of normal spinal cord tissue. With T2 weighting, the signal
intensity is only slightly more than the normal spinal cord, and
the differentiation between an intramedullary and extramedul-
lary location is sometimes difficult. Bar is 5 cm.
scans (17). Intradural extramedullary lesions, including
neurilemmomas, neurofibromas, and meningiomas, are
seen extremely well with MRI (Fig. 9). MRI also helps
distinguish intramedullary lesions of Vascular origin
from spinal cord neoplasms, which they may clinically
mimic (Fig. 10). As our experience with MRI becomes
greater, the need for the more invasive studies such as
myelography and CT scanning will probably become
less.
FIG. 10. This 45-year-old man presented with signs and
symptoms of progressive myelopathy. The high signal inten-
sity, which did not enhance with gadolinium, represented a
hemorrhage into a cavernous angioma. Angiography was
negative for vascular malformations. After surgical evacua-
tion, the patient improved. Bar is 5 cm.

372 / CHAPTER l6
DIFFERENTIAL DIAGNOSIS
Ruptured Intervertebral Discs
Ruptured intervertebral discs commonly compress
cervical or lurnbosacral nerve roots. Aggravation of ra-
dicular pain by activities that stretch the roots is a corn-
rnon sign of root compression. Radicular pain can often
be lessened by certain positions of the limbs and spinal
column that relax tension on the roots, such as ﬂexion of
the arm or leg. These clinical features can also occur with
spinal tumors. However, with spinal tumors, particu-
larly of the cauda equina, there is often little relief from
pain when resting. Lying ﬂat in bed typically exacerbates
the pain, and patients with tumors of the cauda equina
will often sleep in a ﬂexed position or sitting up in bed to
reduce pain.
A midline protruded thoracic or cervical disc may
closely mimic the signs and symptoms ofa spinal cord
tumor. Cervical spondylosis with foraminal encroach-
ment and narrowing of the anteroposterior diameter of
the spinal canal may result in atrophy of the upper ex-
tremities, with accompanying long—tract signs, rnirnick—
ing those signs seen in spinal cord tumors. On myelogra-
phy there may be widening of the spinal cord, with an
appearance similar to that of an intrarrfedullary spinal
cord tumor. With intrinsic spinal cord tumors, however,
the cord is seen to be widened not only in the anteroposte-
rior but also in the lateral projections. The cord—widen—
ing produced by cervical spondylosis, on the other hand,
is due to anteroposterior compression of the cord, which
can be seen on lateral projections to be caused by
narrowing of the spinal canal as a result of ventral osteo-
phytes and a hypertrophic ligamentum ﬂavum.
Degenerative Diseases
In most cases there is little difficulty in differentiating
the degenerative, metabolic, and demyelinating spinal
cord diseases, such as amyotrophic lateral sclerosis, sub-
acute combined degeneration, and multiple sclerosis,
"from spinal cord tumors. However, in an initial attack of
demyelination confined to the spinal cord, myelography
may be required to rule out spinal tumor.
Syringomyelia
Syringomyelia, discussed in Chapter 17, may pose a
difficult differential diagnosis from intramedullary tu-
mors. Indeed, some patients with intrinsic gliornas ofthe
spinal cord may have an associated syrinx. The associa-
tion of skull—base abnormalities and Arnold—Chiari mal-
formation with syrinx may help to make the diag-
nosrs.
OPERATIVE MANAGEMENT
Indications for Surgery
Surgery is indicated for most spinal cord tumors. A
relative exception is a patient who has a known radiosen—
sitive spinal tumor, in which case radiotherapy may be
instituted without performing surgery. Another possible
contraindication to early surgery is encountered in pa-
tients with known intramedullary tumors that are quite
small, with minimal neurologic deficits. One must indi-
vidualize these cases, but because the tumors may be
quite difficult to find at surgery, it is not unreasonable to
wait until the tumor is large enough to produce a signiﬁ-
cant neurologic deficit and to perform surgery at that
time. In the absence of rapid neurologic progression,
most spinal cord tumors may be operated upon elec-
tively, as these tumors are generally slow—growing. The
larger these tumors become, however, the more cornpro—
mised may be the circulation, and thereby the more tenu-
ous is the ability of the cord to undergo surgical manipu-
lation. Surgery, therefore, should be done as expediently
as is convenient. Progressive neurologic loss constitutes
a surgical emergency, and rapid decompression and re-
moval of the tumor may make the difference between a
successful result with return of full function and paraly-
sis. In the cases of impending and progressive neurologic
dysfunction, corticosteroids and dehydrating agents
such as mannitol may be given in order to buy some
time. The surgeon is cautioned not to be misled by tern-
porary improvements but to proceed with surgery as
soon as possible.
Positioning and Anesthesia
In most instances, patients with spinal cord tumors
can be operated on in the prone position. Careful atten-
tion should be paid to correct positioning of the lateral
chest and abdominal walls on properly fashioned and
positioned rolls. They should extend from the clavicle to
the iliac crest, allowing the thorax and abdomen to be
suspended freely to prevent distention of the epidural
veins. As surgery may require many hours, appropriate
padding should be placed over pressure points where pe-
ripheral nerves may becorne damaged, particularly at the
elbows, fibulae, and anterior iliac crests. Three—point pin
fixation of the skull is useful when operating on cervical
lesions to prevent pressure on the forehead and eyes. The
sitting position may be advantageous for certain cervical
tumors, as there is decreased venous bleeding in this po-
sition. Because of the danger of air emboli entering the
cervical veins when operating on a patient in the upright
position, however, the anesthesiologist should place a
Doppler probe over the precordium to detect the pres-
ence of any air emboli, and place an intravenous catheter

into the right atrium to remove air emboli should this
complication occur.
The site of the lesion is carefully identified preopera-
tively, either with prior marking of the skin at the time of
myelography or with intraoperative x—rays. A wide skin
preparation should be performed because extension of
the incision may be necessary, especially in patients with
an intramedullary ependymoma in which the tumor
may extend a considerable number of spinal levels. Full
control of respiration is recommended at all times. This
is particularly important in lesions above C-5, where re-
spiratory problems may develop.
Surgical Technique
General Technique
A midline incision is used for most spinal tumors. Fol-
lowing incision through the skin and subcutaneous tis-
sue, a bilateral subperiosteal muscle resection is per-
formed, using sharp dissection, the electrosurgical
cutting current, or both. Care must be exercised when
the tumor has caused thinning of the laminae because
instruments may easily penetrate the thin bone, resulting
in cord damage. After removal of the spinous processes
with rongeurs, the laminae are thinned, either with ron-
geurs or with air or electrically driven drills, using cutting
burrs and then diamond burrs if the laminae are to be
drilled to only a few millimeters in thickness. If a drill is
used to thin the laminae, the drill should be held firmly
with both hands, with the assistant irrigating the site of
drilling to prevent heat from being transmitted to the
spinal cord. Once the laminae are thinned, a combina-
tion of instruments, including curettes and rongeurs
with thin foot plates, is used to remove the remaining
bone. In general, the caudal portion ofthe lamina should
be removed first, and dissection should proceed superi-
orly, taking care not to place the tip of the rongeur too far
beneath the lamina. As bone removal progresses, the
bone edges should be waxed. This is especially important
in the sitting position to prevent air emboli from gaining
entrance through the diploe. Following exposure, the
dura should be inspected and ultrasound used to localize
the site of the lesion further.
Ultrasound Imaging
In our experience, one of the most useful tools in the
surgical treatment of spinal lesions is intraoperative spi-
nal ultrasonography. Not only can one localize the lesion
intraoperatively, but one can periodically assess the effi-
cacy of the surgical procedure and, following completion
of the operation, determine the extent of tumor resec-
tion. Ultrasonography is particularly sensitive for cystic
lesions and may be more accurate than MRI scanning
SPINAL CORD TUMORS / 373
for these lesions (18). One may arrive at an erroneous
diagnosis of a cystic structure with MRI scanning owing
to variations in the protein content. Ultrasonography
usually shows these areas more clearly at the time of
surgery. Additionally, multiple cysts can be identified,
and this in itself is very useful, especially in tumors that
are nonresectable where drainage of the cystic lesions
can improve the neurologic status by relieving the intra-
medullary pressure. The role ofultrasonography in extra-
rnedullary lesions is even more valuable. One can locate
the lesion and determine its relationship to the spinal
cord, thereby allowing the most direct route to the lesion.
The postoperative assessment of the effectiveness of the
tumor resection is also facilitated by using intraoperative
sonography.
The patient should be positioned in the prone position
so that the laminectomy defect can be filled with sterile
saline. The scan head is then inserted into the ﬂuid—filled
laminectomy site, and both transverse and longitudinal
scans are obtained. These provide a three—dimensional
picture of the spinal cord and its concomitant pathology
prior to opening the dura (Fig. 11). We use a 7.5—MHz
scanner (Advanced Technology Laboratories, Bellevue,
Washington). It is necessary to have meticulous hemosta—
sis prior to scanning because blood and other debris,
such as bone dust from the drill, can be very echogenic
and can prevent the resolution required to make the de-
sired evaluation. The normal ultrasonic anatomy of the
spinal cord must be understood in order to appreciate
the pathologic changes that occur with spinal cord tu-
FIG. 1 1 . The scan head is inserted into the sa|ine—fi||ed lami-
nectomy defect. The spinal cord is scanned without direct
contactwith thetransducer. (From reference 1 8, with permis-
sion. Copyright 1 982 by Elsevier Science Publishing Co., Inc.)

374 / CHAPTER 16
mors. All neurosurgeons should use ultrasonography in
every laminectomy to gain experience with manipula-
tion of the ultrasound scanning head.
Once the laminectomy has been performed and the
dura exposed, the display of the intramedullary anatomy
is very clear. Particularly, one can identify the intramed—
ullary cysts and the relationship of the cyst to the solid
portion of the tumor (Fig. 12). One can see not only the
internal structure of the cyst but also the multiple locula—
tions, septae, and nodules associated with the cyst wall.
This aids the surgeon in applying the safest and most
direct approach through the spinal cord into the area of
abnormal tissue. In our experience, not only does drain-
ing the cyst decrease the mass effect, which improves the
patient's symptomatology, but it provides immediate ac-
cess to the tumor, establishes a cleavage plane, and al-
lows a greater opportunity for a safe and complete re-
moval of the tumor. This is especially true of ependy—
momas.
Intramedullary Tumors
Total removal of ependymomas can be accomplished
in many cases. Complete removal is occasionally possi-
ble for teratomas and epidermoids but only rarely for
astrocytomas (13). The operating microscope should be
used; in most cases a 300—mm objective provides the best
working distance. After the tumor is localized within the
spinal cord, a myelotomy is performed over the thinnest
area of the cord. Vessels overlying the site of myelotomy
should be coagulated with bipolar coagulation under sa-
FIG. 12. A syrinx (white arrow) associated with an epen-
dymoma (black arrow) is shown on ultrasonography in sag-
ittal (A) and transverse (B,C) views. This real—time intraop—
erative evaluation allowed the surgeon to proceed directly
to the syrinx and to identify the caudal end of the tumor.

line irrigation. The cord may be tapped with a 25—gauge
needle to drain a cystic cavity if this has been previously
identified by ultrasound. If ﬂuid is encountered, it
should be partially withdrawn. Some ﬂuid should be left
within the cavity so that the partially filled cyst can be
used to develop a cleavage plane around the tumor.
Using the operating microscope, the surgeon should
inspect all aspects of the tumor to identify a cleavage
plane. Once a cleavage plane is identified, the pseudo-
capsule is grasped with small microforceps, and gentle
traction is exerted. Dissection is carried out in this cleav-
age plane with traction being applied to the tumor and
not the cord. Blood vessels entering the capsule arc coag-
ulated and divided with fine microscissors. Removing
tumor bulk may aid in mobilizing the tumor and in dis-
section of the cleavage plane. Two comparatively new
instruments are useful for removing the bulk of the tu-
mor: the ultrasonic aspirator, which fragments and
disrupts the tumor, and the surgical laser, which vapor-
izes tissue.
The Cavitron Ultrasonic Surgical Aspirator (CUSA) is
a self—co1rtai1red system with a hand—held emulsifying tip
with a combined irrigation and suction device (Fig. 13).
Handpiece cable
carries both power and
cooling water through
the handpiece.
Electric coll
receives low voltage
electrical current from
the console and activates
the transducer.
Magnetostrictive
transducer is rugged
and highly stable;
converts electromagnetic
energy into mechanical
vibration.
Connecting body
mechanically couples and
amplifies the motion of the
transducer at the tip.
Irrigation
is controlled at the console,
and directed through the
space between the tip and
the protective flue.
Aspiration
is accomplished through
the tip by a suction pump
contained in the console.
Tip of hollow titanium
fragments tissue which
is then aspirated away
from the surgical site.
FIG. 1 3. The working end of the Cavitron Ultrasonic Surgical
Aspirator (CUSA). (From reference 19, with permission.)
SPINAL CORD TUMORS / 375
The surgeon activates the vibrating tip with a foot pedal
while the amplitude of the vibrating tip, the amount of
suction, and the volume of the irrigation are regulated at
the console. The CUSA's ultrasonic dissection system
fragments tissue at the vibrating tip, suspends the frag-
mented tissue irr irrigation solution, and then aspirates
the tissue—irrigation complex. Laboratory studies of the
CUSA system demonstrate that normal electric co1rduc—
tion in nervous tissue is maintained beyond 1 111111 from
the vibrating tip. This allows surgeons to remove tumor
tissue without causing neural trauma to adjacent vital
structures (19). When debulkirrg these tumors, one can
safely remove the intratumoral contents, proceeding out-
ward toward the capsule with gentle stroking motions.
We prefer to set the system at the lowest level of vibra-
tion arrd suction possible to achieve the desired results,
increasing vibration, amplitude, and suction levels only
if necessary. When the device is set at the maximum
vibration stroke and speed, even firm tumors such as
meningiomas and acoustic neuromas are easily frag-
mented arrd aspirated. Unfortunately this system is not
very effective in tumors with calcifications, such as cra1r—
iopharyngiomas or calcified meningiomas. Although ex-
tramedullary tumors such as neurofibromas and n1enin—
giomas are nicely dcbulked using this system, we find
that its most practical application is with intramedullary
tumors such as astrocytomas and ependymomas. One is
actually able to stay within the substance of the tumor,
gently stroking the tissue until one reaches either a place
in the capsule where a cleavage plane can be established
or, in the case of a diffuse astrocytomas, a place where
one can actually proceed with dissection until the ede1na—
tous surrounding peritumoral white matter is e1rcou1r—
tered. Tumors that were partially resectable can be more
aggressively approached with less chance of damage to
the surrounding neural structures. Unfortunately, hemo-
stasis is not obtained using the ultrasonic aspirator.
Therefore, periodic pauses must be made for hemostasis
using bipolar coagulation. The tactile feedback afforded
by the CUSA, aided by magnification with the operating
microscope, is valuable to the surgeon; with experience,
a surgeon can feel and see the differences between the
tumor and the peritumoral interface.
If a clear line of demarcation between spinal cord and
tumor cannot be maintained, it is best to transsect the
dissected tumor and leave the remaining tumor, because
persistence in dissection may result in neurologic dam-
age. If a total removal has been achieved, the dura may
be primarily closed if it can be closed easily without terr-
sion orr the cord. If tension is present, or if a subtotal
resection has been performed, the surgeon should use a
patch to close the dura, using either lumbodorsal fascia
or a dural substitute. When subtotal resection has been
performed, or when there has been a prolonged opera-
tive time, arr alternative technique is to patch the dura,
close the wound, and reoperate after 7 to 10 days. The

376 / CHAPTER l6
pulsation of the spinal cord may deliver the remainder of
the neoplasm and make possible a total removal of the
neoplasm. Some intramedullary lesions, such as epider-
moid tumors, may not be amenable to total removal.
Drainage of any cystic component and partial removal
may provide satisfactory results, however, because these
tumors usually grow slowly.
Intradural Extramedullary Tumors
In addition to the general principles described earlier
for laminectomy, other operative points should be em-
phasized. The dura should be opened on the side of the
tumor, and, if possible, the arachnoid should be pre-
served or opened only over the tumor. With meningio—
lmas, the dural attachment should not be separated from
""the tumor. Rather, the attachment should be left in place
and the dura opened circumferentially around the le-
sion. Most of these tumors are located dorsally, and their
removal is facilitated by small traction sutures applied to
the dural attachment of the tumor. Traction is always
applied to the tumor, never to the cord, and the tumor is
dissected away from the cord. Although it is tempting to
remove these lesions en bloc, the safest method of re-
moval requires that these tumors be removed in a piece-
meal fashion by gutting the inside of the tumor and leav-
ing the surrounding tumor capsule intact.
The laser can be quite beneficial in debulking and re-
moving extramedullary tumors such as neurilemmo—
mas, neurofibromas, and meningiomas. However, the
tactile feedback of the CUSA may outweigh certain ad-
vantages of the laser, and therefore the CUSA may be
preferable in most instances for removal of these lesions.
In very dense, firm tumors with calcification, though,
the laser may be superior to the CUSA. Experience with
both the laser and the CUSA are therefore essential for
treatment of the different tumor types.
Once the tumor is debulked, the surgeon can manage
the tumor capsule more easily and can dissect it away
from the cord using microtechnique. As traction is
gently applied to the tumor, bridging vessels between the
tumor capsule and the cord can be visualized, coagulated
with bipolar coagulation under irrigation, and sectioned
with microscissors.
In lesions that are ventrally placed it is necessary to
divide the dentate ligaments and occasionally the dorsal
roots to facilitate gentle rotation of the cord (Fig. 14). In
the thoracic area, section of the ventral roots results in
minimal neurologic sequelae. In the upper cervical area,
one or two dorsal roots may be sectioned to facilitate
cord rotation. This may be necessary for lesions in the
area of the foramen magnum.
Removal of neurilemmomas is facilitated by dividing
the nerve root or rootlets to which the tumor is attached.
Traction may then be applied to the tumor using the cut
nerve root. Radicular arteries accompany the nerve
FIG. 14. lntraoperative photograph of an intradural extramed—
ullary neurofibroma. Dentate ligaments were sectioned (black
arrow) to gain access to the ventral portion of the tumor. Note
the attachment of the dorsal root to the tumor (white arrow).
A total removal was accomplished, and the patient made a
full recovery.
roots, and. prior to sectioning roots, these blood vessels
should be carefully dissected away from the roots and
spared.
Following removal of the neoplasm, the dura is
patched in a water—tight fashion. In more ventrally
placed meningiomas, it may not be possible to patch the
dura adequately, and in such cases it is acceptable to
insert a piece of fascia between the spinal cord and the
underlying bone.
In cases having both intradural and extradural exten-
sion of the tumor, the intradural portion is removed first,
followed by removal of the extradural portion. These
tumors occasionally grow in a dumbbell fashion through
the neural foramen into the soft tissues of the neck or
into the chest. Following removal of such tumors, and
especially if a second extraspinal procedure is planned, a
water—tight dural closure is mandatory to prevent a sub-
sequent CSF fistula into the neck or thoracic cavity.
Epidermoids, Lipomas, and Ependymomas
of the Conus Medullaris and Cauda Equina
Lipomas that are intimately wrapped in and about the
nerve roots of the Cauda equina often cannot be totally

removed. Because these are benign and grow slowly, sub-
total removal is acceptable. Should the tumor recur, re-
operation is indicated. Ependymomas in the area of the
conus medullaris are also often impossible to remove
totally. Although exophytic components of this tumor
may at first appear to be extrarnedullary, meticulous and
patient dissection often reveals these tumors to be intra-
medullary in origin. If clear—cut cleavage planes cannot
be discerned, subtotal resection is indicated, especially if
there are minimal neurologic deficits preoperatively.
Postoperative Care and Complications
Physiotherapy is initiated immediately postopcra—
tively to prevent the complications of atelectasis, pneu-
monia, and pulmonary embolism. When there has been
extensive compromise of the muscles of respiration, me-
chanical ventilation may be necessary for a short period
of time.
Many patients will have temporary neurogenic blad-
ders, which will require indwelling catheters. After a
short period of time, intermittent catheterization should
be initiated to minimize infection.
Pressure sores and decubiti develop quite quickly if
proper precautions are not taken. Bony prominences
should be padded with sheepskin mattresses and booties.
A water bed, rotobed, or Stryker frame should be used,
with regular turning every two to four hours, if neces-
sary.
Ileus often occurs following spinal surgery. Nasogas—
tric suction usually decompresses the gastrointestional
tract, and within a short time normal motility returns. A
distended abdomen secondary to gastric atony or intes-
tinal ileus may compromise respiration and lead to vo1n—
iting and concomitant aspiration.
Pulmonary embolus is a particular hazard in older pa-
tients. Paretic limbs should be examined daily for evi-
dence of venous thrombosis. Antiembolic stockings
should be worn if the limbs are paretic. Early recognition
and prompt treatment of venous thrombosis with antico-
agulants may be necessaiy to prevent pulmonary e1nbo—
lisrn.
Extensive laminectomies, especially in the young, can
destabilize the spine and may result in a swan—neck defor-
mity. Radiation therapy applied to the spinal neuraxis in
the preadolescent patient can result in marked deformity
of the spine owing to radiation changes in the growth
centers (Fig. 15).
“Postoperative Radiation Therapy
The effectiveness of radiotherapy in primary intra1ned—
ullary tumors has not been established with certainty for
each type of tumor. Connolly has suggested that "postop—
erative radiation after subtotal removal of these tumors
appears to be a logical course as, in the brain at least,
SPINAL CORD TUMORS / 3771
FIG 15, This 14-year-old boy presented with progressive
quadriparesis Al the age of five, he had a biopsy of an astro-
cytoma and was treated with spinal irradiation. He slowly de-
teriorated and developed a progressive swan—neck defor-
mity. MRI demonstrated a multiloculated syringomyelic cavity
from C-7 to T—7 associated with cord atrophy. At reoperation,
the pathology consisted of areas of low—grade astrocytoma
and findings suggesting radiation necrosis. Bar is 5 cm.
these lesions have been demonstrated to be radiosensi—
tive and it follows that if radiation therapy is to be most
effective it should be utilized when the tumor population
is smallest" (14). Wara and Sheline summarized the re-
sults for radiation therapy for biopsied astrocytomas and
for intrinsic tumors of the spinal cord that were not biop-
sied. The rates of recurrence—free survival for two to five
years were 61 percent for patients with an astrocytoma
and 70 percent for the patients with an unbiopsied spinal
tumor (20). They believe that, although these data are
inconclusive, radiation therapy has at least an inhibiting
effect on the growth of astrocytomas. These authors also
reviewed radiotherapy of ependymomas of the spinal
cord and concluded that postoperative radiation therapy
for the patient with an incompletely resected ependy-
moma increased the survival time and that long—term
control could be achieved in many of these patients.
Linstadt and associates reviewed 42 patients with a
primary tumor of the spinal cord or cauda equina who
received x—ray therapy between 1957 and 1986 (21).
Thirty —nine (93 percent) of these patients received a total
radiation dosage ranging from 45.0 to 54.1 GY, using
standard fractionation. Their conclusion after analyzing
the results suggested that patients who undergo postoper-
ative irradiation for a low—grade spinal astrocytoma or
localized spinal ependymoma have excellent survival.
Garcia reported on 37 patients with a primary spinal
cord tumor who received postoperative radiation after
laminectomy (22). There were 26 intramedullary tu-
mors, which included 14 astrocytornas and 8 ependymo-

378 / CHAPTER 16
mas, and 11 tumors of the conus medullaris or cauda
equina. The ﬁve— and ten—year actuarial survival rates for
the entire group were 70 and 58 percent, respectively.
The most important predictor of neurological function
was the anatomic site of the tumor. Patients with a tu-
mor of the cauda equina had better neurological func-
tion and survival than patients with a tumor at another
site. Recurrent tumor was the cause of death in 82 per-
cent of the patients who were dead at the time of the
study. Of the 20 patients alive at the end of the study, 10
were completely normal or had only mild neurological
deﬁcits. The remaining 10 were severely disabled. Garcia
noted that an increased radiation dose correlated with an
increase in tumor control and survival. Of the patients
who received less than 40 GY, 77 percent died of recur-
rent tumor; however, 83 percent of those who received
greater than 40 GY were alive 4.1 to 28.9 years after
treatment.
RESULTS
Neurologic function after partial removal of astrocy—
tomas may be quite satisfactory for many years. Epstein
attempted gross total excision in 120 patients with an
intramedullary spinal cord tumor (23). His experience
led him to observe that "Holocord" widening occurs in
approximately 60 percent of all cases and that it is
usually diagnostic of a cystic astrocytoma. Despite the
absence of a surgical plane of dissection between the glial
tumor and its interface, he recommends removing these
tumors from the "inside out" until reaching the tumor
interface. He concluded that radical tumor excision is
compatible with partial or total recovery of neurologic
function but that the success of the surgery is also di-
rectly related to the preoperative neurologic status of the
patient.
Cooper and Epstein reported their experience in 29
patients with an intramedullary spinal cord tumor, 14 of
which were ependymomas and 11 astrocytomas (24).
Total removal was accomplished in 14 patients, and 99
percent removal in seven others. They noted that cysts
were more common than previously thought, often de-
fining the upper and lower ends of the tumor. Ependy—
momas were usually well deﬁned from the surrounding
tissue. The researchers believed that a glial tumor inter-
face could be developed, even in diffuse astrocytomas. In
many patients with astrocytomas, neurologic deteriora-
tion was arrested, and improvement had occurred. They
concluded that "radical operation provided significant
palliation and at best, it is possible that many patients
would be cured of their tumors" (24).
It is my opinion that the following guidelines should
be established. If the primary spinal tumor is an ependy-
moma, every attempt should be made to resect it as corn-
pletely as possible, and the patient should be followed
closely clinically and with serial MRI scans. Whether to
reoperate or to give x—ray therapy to the local area can be
decided based on this information. In view of the litera-
ture and personal experience, I would defer radiotherapy
if gross total removal has been accomplished. Subtotal
removal of ependymomas is probably best treated with
x—ray therapy to the affected area. If the tumor is found at
surgery to be a diffuse astrocytoma, total removal should
be attempted. If a cleavage plane is not possible to de-
velop and there is no way of differentiating between glial
tumor interface and neoplasm, I do not attempt extirpa-
tion. I would then recommend radiation to the affected
area after a wide decompressive laminectomy has been
performed.
REFERENCES
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3. Mulder DW. Dale AID. Spinal cord tumors and disks. In:Baker
AB, Baker LH. eds. Clinical neurology. Hagerstown, MD: Harper
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4. Gowers WR. Manual of diseases of the nervous svstem. vol 1. Lon-
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5. Gowers WR. Horsley VA. A case of tumor of the spinal cord:
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6. Elsberg CA. Diagnosis and treatment ofsurgical diseases of the
spinal cord and its membranes. Philadelphia: WB Saunders, 1916.
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strument for applying coagulation current in neurosurgery. Am J
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CHAPTER 17
Syringomyelia
Principles ofNeitrosiirgery,
edite( by Robert G. Grossman. Rosenberg g 1991.
Published by Raven Press, Ltd., New Yor .
Howard M. Eisenberg and Richard L. Weiner
Pathogenesis, 381
Clinical Features, 383
Diagnosis, 383
The condition of chronic disability caused by cavitation
of the spinal cord was first termed Syringomyelia by Olli-
vier d'Angers. In a monograph published in 1824, Olli-
vier described pathologic dilatation of the central canal
of the spinal cord in continuity with the fourth ventricle
(1). The occurrence of spinal cord cavitation with dilated
ventricles had been described more than 100 years ear-
lier (2). However, even though an association of spinal
cord cysts with alteration of cerebrospinal fluid (CSF)
dynamics continued to be commented upon in the medi-
cal literature, Syringomyelia, until recently, was com-
monly attributed to other etiologies, the most popular
being ischemic injury. Credit for popularizing the View
that a hydrodynamic mechanism plays a role in most
cases is owed to Gardner and his associates (3-8). He and
others (9,10) have suggested the term communicating
Syringomyelia to differentiate this condition from the
less common condition in which etiologies such as tu-
mor, focal spinal cord arachnoiditis, or trauma cause
'iofatecf cysts. Although there is now general acceptance
of the hydrodynamic theory, the sequence of changes
that results in the development of the cyst, its increase in
size, and the progression of disability is not completely
resolved. Histologic examination has shown that these
cysts are surrounded by gliosis, although in some sec-
tions the lining may, in part, be ependymal, indicating
that they originate from the central canal. Dilatation of
the central canal is usually termed hydromyelia and may
be viewed as an early change in the hydrodynamic pro-
cess. The term syrinx is used for a diverticulum of the
H. M. Eisenberg: Division of Neuro surgery, The University
of Texas Medical Branch, Galveston, Texas 77550.
R. L. Weiner: The University of Texas Southwestern Medi-
cal School, Dallas, Texas 75321.
381
Treatment of Communicating Syringomyelia, 384
Noncommunicating Syringomyelia, 385
References, 386
central canal. It is not of great importance to make a
distinction between these two entities; frequently, these
terms are used interchangeably and may not be clinically
distinguishable. In fact, Gardner and, later, Rhoton (1 1),
have suggested adopting the term hydromyelia to denote
communicating Syringomyelia, since historically syrin-
gomyelia had indicated an untreatable condition. Clini-
cally, the condition is characterized by spasticity and
alteration of sensation due to injury of short— and
long—fiber tracts and to atrophy secondaiy to injury of
anterior horn cells. Although it is often insidious in its
onset, it is thought to be almost always progressive. In
many patients, a lack of early characteristic findings may
result in misdiagnosis and unrecognized cases.
PATHOGENESIS
Syringomyelia is now recognized as one of many con-
ditions caused" by an alteration ofCSF dynamics. In the
early 1950s, Gardner proposed that in most, if not all,
cases this alteration was imposed by associated abnor-
malities of the hindbrain, the most common being cere-
bellar ectopia, the Chiari malformation, which he found
in 68 of his 74 cases (3). While a similar proposal had
been made 30 years earlier by Taylor and coworkers
(12), Gardner developed the idea and published his find-
ings over three decades. The pathologic substrate is a
partial obstruction of the normal midline outflow of the
fourth ventricle, and a patent central canal that commu-
nicates with the fourth ventricle. Gardner believed that
this condition originated in embryonic life as a progres-
sive overdistention of the neural tube, first as a dilatation
of the central canal and later as a diverticulum of the
central canal that retains its connection with the ventricu-

382 / CHAPTER 17
lar system, destroying the spinal cord and, in some cases,
the brainstem as well.
The important clinical evidence in support of
Gardner's theory includes the following observations:
the Chiari malformation or another obstructive lesion
causing partial blockage of the midline outlet of the
fourth ventricle is found in most cases; the fluid within
the spinal cord cyst is virtually identical to CSF; commu-
nication between the Ventricular system and the cyst can
be demonstrated by injection of dye during operation, or
with gas or contrast during myelography; and improve-
ment or stabilization of symptoms can occur after relief
of the obstruction. The theory was challenged by those
who reported that they could not find a communication
between the cyst and the ventricles at autopsy, or that
radiographic studies did not show dilatation of the up-
permost segments of the spinal cord. It is now known,
however, that dilatation of the central canal in the upper
segments (C1 and C2) is almost always minimal, presum-
ably due to the restricting effect of the decussating fiber
tracts and impingement of the ectopic tonsils. Because of
the minimal dilatation of the canal at this level, patency
may be missed when studying autopsy specimens.
Animal experiments have yielded evidence comple-
mentary to Gardner's observations. In 1954, McLaurin
and coworkers found that dogs made hydrocephalic by
installation of a suspension of kaolin into the cisterna
magna developed dilatation of the central canal and spi-
nal cord cavitation (13). In some of the dogs, cysts could
be demonstrated to be in communication with the
fourth ventricle but, because there was an intensive ad-
hesive inflammatory process of the cervical meninges,
they accepted their observations as evidence of an ische—
mic cause for cavitations. A similar experiment was
made earlier by Camus and Roussy, who also attributed
the cysts that they found to ischemia (14). Twenty years
later, Becker and coworkers repeated these experiments
in cats (15). They found that after development ofhydro—
cephalus the central canal of the spinal cord dilated as far
down as the filum terminale. In some animals, they were
able to show a communication of dye between the fourth
ventricle and the dilated central canal. They found,
moreover, that the dilatation of the central canal and the
associated cysts could be prevented if the central canal
was plugged in the region of the obex. By measuring CSF
absorption (16) and the use of radioisotope scanning
techniques (17), Eisenberg and coworkers showed that
the dilated central canal, communicating at one end
with the obstructed ventricular system and at the other
with the spinal subaraclmoid space through the filum
terminale, is the pathway for CSF outflow in this experi-
mental model of hydrocephalus. The absorption of spi-
nal ﬂuid takes place from the spinal subaraclmoid space.
When kaolin was injected into the cisterna magna of
cats, the animals first appeared acutely ill and their intra-
ventricular pressure was high. After several days, the cats
recovered. At this time, the ventricular pressure had re-
turned to normal or nearly normal. However, despite
this return to normal pressure, ventricular dilatation, hy-
dromyelia, and spinal cord cavitation progressed. The
animals eventually developed signs of spinal cord injury,
most frequently paraplegia. When the cord was re-
moved, a dilated central canal was found, generally
through its entire length. This model of experimental
hydrocephalus is in many ways like human syringomye—
lia, and mimics cases of myelomeningocele, in which
hydromyelia and hydrocephalus are constant fea-
tures (18).
In patients with Arnold—Chiari malformation due to
myelomeningocele, symptomatic hydromyelia can be
demonstrated when the associated hydrocephalus is not
relieved (6). Hydrocephalus is not, however, a constant
feature of communicating syringomyelia associated with
the Chiari I malformation. Although Gardner, quoting
Netski, reported that patients with syringomyelia usually
have dilated ventricles (7), Barnett and coworkers found
that only 1 1 of their 100 patients had enlarged ventricles
(9). Several other reports of series of patients with com-
municating syringomyelia also have shown that the inci-
dence of associated hydrocephalus is low (11,19). The
apparent paradox ofpartial obstruction ofthe fourth ven-
tricular system causing hydromyelia and syringomyelia,
but no hydrocephalus, has provoked interesting specula-
tion. Gardner believed that a semipermeable membrane
blocked the outlets of the fourth ventricle and allowed
for equalization of mean pressure, but not peak pressure.
At peak ventricular pressure, the membrane reflected
fluid into the central canal. This water—hammer effect of
peak pressure caused the progressive dilatation of the
central canal.
Williams offered an alternative hypothesis and attrib-
uted the dilatation of the central canal and spinal cord
cysts to alterations of venous pressure (20,21). He found
that a bidirectional flow of CSF occurred during a period
of elevated venous pressure, such as during coughing or
straining. When he simultaneously measured the pres-
sure at the cisterna magna and at the lumbar subarach-
noid space in normal subjects, he found that when ve-
nous pressure increased, the lumbar pressure rose before
the cisternal pressure, causing an initial flow into the
head. A secondary caudal flow occurred when the cister-
nal pressure exceeded the lumbar pressure. The cisternal
elevation was longer lasting. Normally, flow at the fora-
men magnum in both directions was through the sub-
arachnoid space. In patients with cerebellar ectopia, Wil-
liams proposed that the herniated tonsils act as valves,
allowing the initial upward flow through the subarach-
noid space, but when the pressure reverses, the tonsils
impact and downward flow is diverted into the central
canal. Other factors that may account for the discrep-
ancy between the dilated central canal and the normal
ventricular system include the greater distensibility of

the spinal dural sac (compared with the intracranial
dural sac), and the differences in elasticity between the
tissue surrounding the central canal (gray matter) and
that surrounding the ventricles (white matter). Recently,
the etiology of the Chiari malformation has been reevalu-
ated. New observations indicate that cerebellar ectopia
may not be a primary developmental abnormality, but
rather the result of a relatively greater rate of CSF ab-
sorption from the spinal subarachnoid space than from
the cranium (21,22). If this is so, the ectopia would be a
true herniation in response to a difference in pressures in
the two compartments—cranial and spinal.
CLINICAL FEATURES
The pattern of symptoms seen in communicating sy-
ringomyelia depends on the progression of the cyst and
its configuration in the spinal cord. In almost all cases,
the cervical cord is involved and, in many, the thoracic
and lumbar segments are affected as well. A few cases
have been reported in which the cyst predominantly in-
volved the lower portion of the cord. Rostral cavitation
is not uncommon and may cause brainstem abnormali-
ties. The symptoms usually first appear between adoles-
cence and middle adult life. In one study of 60 cases, the
mean age of onset was approximately 30 years (19).
Cases in which the symptoms begin before age ten or
after age 60 are less common. Males and females appear
to be equally affected. The majority of patients present
with a mixture of motor and sensory abnormalities, al-
though altered sensation is frequently the earliest noted
abnormality (11). The clinical course is variable but, in
most instances, progression can be established, particu-
larly when patients are observed for at least five years
(19). Rapid progression of symptoms may occur, particu-
larly in patients who notice the onset of symptoms in
adolescence or in their early 20s (19).
The motor abnormalities commonly include weak-
ness and atrophy of the hands. Obvious signs of spastic-
ity of the lower extremities usually occur later, although
stiffness of the legs is an early common complaint (9).
The motor abnormalities frequently, but not always, are
bilateral, although unilateral motor deﬁcits are more fre-
quent in the early stages (11). Diminished deep tendon
reﬂexes in the upper extremities and increased reﬂexes in
the lower extremities occur in approximately 60 percent
of patients (9,19). The sensory abnormality most com-
monly associated with the condition is a suspended, dis-
sociated loss of pain and temperature sensation in a
capelike distribution involving the shoulders, arms,
hands, and upper trunk. This pattern was found in 40
percent of patients in one series (19). The abnormality is
presumed to be owing to segmental compression or de-
struction of the anterior commissural ﬁbers by a central
cervical cavitation, while the ascending tracts are spared.
Other patterns of suspended sensory loss arc less com-
SYRINGOMYELIA / 383
mon. Also less commonly found are abnormalities of
proprioception. When they occur, the upper extremity is
involved most often, while the lower extremity is unaf-
fected. This is most likely due to injury or compression
of the dorsal root—entry zone in the cervical region. Neck
pain and extremity pain, as well as headache, are also
common complaints (9,23). Brainstem involvement has
been found in approximately one—third of patients.
Other abnormalities include upper and lower motor dys-
function of cranial nerves, nystagmus, alteration of fa-
cial sensation, and impaired movement of the tongue
and swallowing. Horner's sign has been observed (9). Ab-
normalities involving ventilation, particularly during
sleep, have also been reported. These symptoms may be
due to injury to the respiratory centers in the medulla
and diminished responsiveness to hypercapnea. Two
cases of obstructive sleep apnea have been reported. The
cause of sleep apnea in these cases is attributed to failure
to maintain patency of the upper airway due to prolapse
of the tongue and impaired control of pharyngeal mus-
cles (24,25).
DIAGNOSIS
Plain x—rays of the head and spine, although frequently
normal, may be important in demonstrating associated
bony abnormalities of the skull base and spine. These
may include the Klippel—Feil deformity, atlanto—occipi—
tal fusion, basilar impression, and widening of the cervi-
cal canal. Scalloping ofthe vertebral bodies and thinning
of the pedicles, as well as other findings of intramedul—
lary tumors, however, usually are not seen in communi-
cating syringomyelia. Kyphoscoliosis is relatively com-
mon, particularly in younger patients, and may be the
presenting symptom in children. Three of 12 children
with syringomyelia associated with a Chiari I malforma-
tion and no dysraphism had scoliosis in a series reported
from the Hospital for Sick Children (26). These plain
x—ray findings are, of course, not diagnostic.
In the pre—MR imaging era, the diagnosis ofcommuni—
cating syringomyelia was a relatively complicated mat-
ter. Diagnosis relied primarily on standard myelography.
which could demonstrate cerebellar ectopia and a wid-
ened cord. This was replaced, at least in some centers, by
gas myelography. Using this technique, there was diag-
nostic certainty in those cases in which a widened cord
could be shown to collapse. Later, CT scanning demon-
strated a normal ventricular system without evidence of
hydrocephalus in almost all cases (with the exception of
those with Chiari II and myelodysplasia). Using CT, the
diagnosis was made by myelography and delayed
images, which showed a widened cord, frequently with
an intramedullary cyst.
MR scanning has replaced all of the above techniques
and clearly shows the ventricular system, cerebellar ab-
normalities, other posterior fossa pathologies, and the

384 / CHAPTER 17
syrinx throughout its extent in the spinal cord (Fig. 1).
Serial postoperative imaging can be used to assess easil>
the volume of the syrinx and the efficacy of the therapy.
Trweighted images are useful for showing the extent and
the anatomy of the cyst; the cyst ﬂuid should not be
different from the CSF. Generally, the cysts are smooth-
surfaced, regular, and continuous. However, sagittal
images of the cyst sometimes show a septated pattern
appearing as a "string of beads" or "stacked coins"
(27,28). It is not clear whether or not these septa repre-
sent loculations of the cyst and, therefore, whether or not
they are of therapeutic importance. T2-weighted images
are also important because they are more likely to dem-
onstrate a tumor, if one is present. However, T2-
weighted images may show increased intensity in the spi-
nal cord, even in patients without tumors. In one series,
histology in 2 of 13 cases indicated that this change in T2
images may represent gliosis (29). Consequently, it has
been‘ shown that gadolinium can be used in those cases
in which there is uncertainty as to whether or not the cyst
is part of a neoplastic process (30). The CSF flow—void
sign is frequently seen. In one study, flow voids were
found in nearly 40 percent of the patients and were
thought to be due to pulsatile movement within the syr-
inx. It may be possible, using ECG—gated imaging with
special computer techniques, to image flow more pre-
cisely within the cyst (31).
Occasionally, it may be important to examine the cyst
fluid at operation to help make the diagnosis. Using MR
imaging, it seems unlikely that communicating syringo-
myelia would be confused with an isolated cyst
associated with a tumor, but in those cases that remain
unclear, examination of the CSF is useful. In communi-
cating syringomyelia, the fluid aspirated from the cyst is
clear and colorless. Yellow ﬂuid, or fluid with elevated
protein concentration, indicates an isolated cyst, most
commonly associated with a neoplasm.
TREATMENT OF
COMMUNICATING SYRINGOMYELIA
The early surgical management of syringomyelia was
directed at just the intramedullary cyst. Bony decom-
pression was generally followed by cyst aspiration, my-
elotomy. and marsupialization or some other form of
drainage. It was not until Gardner's reports that atten-
tion was focused on the cervicomedullary junction.
Gardner's management of 74 patients over a 25-year pe-
riod reﬂected his ideas about the pathogenesis of the con-
dition. As mentioned earlier, all of his patients had ab-
normalities of the hindbrain, the most common being
the Chiari I malformation. He suggested that establish-
ing normal CSF flow was the most important objective
of the operation. This was done by decompressing the
tonsilar impaction at the foramen magnum and upper
cervical canal and incising any obstructing membrane
found. He also placed a muscle or silk—suture plug in the
rostral portion of the central canal in the region of the
obex. In many of his patients, a widened cord was dem-
FIG. 1 . MR images of a 58-year-old woman wun a seven—year history of numbness and burning in both
hands and arms. Two years before operation her voice became hoarse. Neurological exam demon-
strated fasiculations of the tongue and f power in all groups in her hands and arms. There was de-
creased sensation to pin prick in the arms and hands. The preoperative image (A) shows the Chiari
malformation with hydromyelia. After operation (B), which consisted ofduraplasty, plugging of the cen-
tral canal at the obex, and shunting of the cyst, the cyst is shown to have collapsed. The patient's
symptoms improved.

onstrated and, in some instances, the cyst contents were
also aspirated.
Gardner's operation has now been modified, and mi-
crosurgical techniques are used to open the fourth ven-
tricle. Plugging the central canal at the obex, however, is
thought to be important by some surgeons, but not by
others. The standard operation includes a posterior fossa
decompression via a low occipital craniectomy, and a C1
to C3 or C4 laminectomy. The posterior rim of the fora-
men magnum is removed, and the dura carefully
opened. The ectopic tonsils are separated and, when nec-
essary, the overlying membrane incised, making an
opening into the fourth ventricle. When the membrane
consists of dense fibrous tissue firmly attached to the
underlying cerebellum, as in cases of arachnoidal scar-
ring without cerebellar ectopia, the scar should not be
widely excised. Care should be taken when making an
opening in this membrane; the fenestration should be
high enough to enter the ventricle directly without injur-
ing the medulla or high cervical cord. The cervical cord
is inspected, and the syrinx is drained. Rhoton recom-
mends entering the spinal cord by a posterior lateral ap-
proach, at the upper cervical region, in the dorsal root
entry zone between the lateral and posterior columns, on
the side of the greatest sensory deficit (11). He observed
that the overlying spinal cord tissue usually is thinnest in
this region and thus usually affords easy exposure of the
cavity with little risk of further sensory deficit. By avoid-
ing the posterior midline, the dorsal columns are not
injured, and kinesthetic or vibratory sense loss is pre-
vented. A silastic shunt is guided into the cavity, an-
chored at the dura, then passed into the subarachnoid
space. The narrow—g auge shunt tubing designed for atrial
shunts is well suited for this.
Passing a shunt catheter into the cyst may be difficult
at times. In these cases, particularly if it seems that de-
compression of the cyst is inadequate, the cyst can be
imaged at operation, using ultrasound. This technique is
particularly recommended when the cyst in the preopera-
tive MR images appears septated (32,28). Ultrasonogra—
phy is accomplished more easily with the patient in a
prone position but may also be done with the patient
placed in a seated position by forming a water pocket,
using a plastic adhesive drape attached to the edges ofthe
wound (28). The posterior fossa is closed, but in decom-
pressed fashion. This is achieved by making a water—tight
dural closure, using a patch graft of dura or fascia lata.
The results of this operation have been encouraging,
with improvement or stabilization reported in a least
two—thirds of patients (9,11,19).
If follow—up MR images do not show collapse of the
cyst—particularly when the patient's symptoms have
not resolved and provided that there has been adequate
decompression of the posterior fossa, including its dura
—conversion of the cyst—subaraclmoid space shunt into
a cyst—plural or a cyst—peritoneal shunt is the next step.
SYRINGOMYELIA / 385
Some surgeons recommend this kind of shunt as the ini-
tial procedure, even when there is tonsilar herniation,
provided the herniation does not appear to be the direct
cause of the neurological picture. It remains unclear
whether this treatment alone is adequate for patients
with communicating syringomyelia. In most series,
there appears to be effective relief of pain, but improve-
mentor stabilization of other symptoms (weakness, spas-
ticity and sensory deficits) seems more variable (33-36).
Many of these reports included relatively small numbers
of patients with communicating syringomyelia, as well
as patients with traumatic and neoplastic cysts. Whether
or not this operation, which is less complicated than the
Gardner operation, is as effective, and for which patients
it is suited best, can only be decided by studying a larger
series ofpatients, using serial postoperative MR imaging.
Other methods of treatment have also been recom-
mended. Percutaneous aspiration of the cyst cavity has
been reported to be a relatively safe and simple proce-
dure that can be done under local anesthesia, using radio-
logic control (37,38). Aspiration can be repeated and
may give long—lasting relief of symptoms (19). Shunting
of the ventricular system has also been suggested as a
mode of therapy. Krayenbuhl reported 22 cases in which
mild to marked hydrocephalus was associated with sy-
ringomyelia (39). These patients were treated with a ven-
tricular shunt. Thirteen had substantial improvement; 6
of the 13 patients had previously had primary cervical
decompression without benefit. However, it should be
recalled that in most of the reported series of patients the
incidence of hydrocephalus is low. In 1976, Gardner and
coworkers suggested that cutting the filum terminate—a
procedure they called terminal ventricul0st0my—de—
compresses the syrinx by allowing ﬂuid to flow caudally
into the spinal subarachnoid space (8). Unfortunately, in
most cases, the operation does not appear to produce
lasting effects (19,40). The resistance imposed by the
caudal central canal may be too great to allow a proximal
cyst to empty adequately.
An unanswerable question that has been raised by MR
imaging is what, if anything, should be done with pa-
tients incidentally found to have a totally asymptomatic
cyst. Review of the literature indicates, as noted above.
that symptomatic communicating syringomyelia isa pro-
gressive disease. Patients with large cysts and cerebellar
ectopia, even if asymptomatic, should be made aware
that the best available evidence indicates that they have a
progressive condition that may stabilize only after opera-
tion, and that they should be offered the option of having
surgery.
NONCOMMUNICATING SYRINGOMYELIA
This chapter has concentrated on communicating sy-
ringomyelia. Spinal cord cysts due to other etiologies,

386 /
CHAPTER 17
such as tumor, focal spinal cord araclmoiditis, and
trauma, frequently are isolated. These cysts have been
termed nancammunicating syringomyelia. There are
cases of spinal cord cysts that occur in a setting of focal
araclmoiditis or after trauma, in which the lesion con-
tains clear, colorless ﬂuid with a low protein co1rcentra—
tion (9). These cysts are usually not associated with hind-
brain abnormalities or other causes of obstruction ofthe
fourth ventricle, and communication with the ve1rtricu—
lar fluid cannot be demonstrated. Although these cases
have been termed norrcommunicating syringomyelia,
the pathogenesis ofthese cysts remains unclear. The best
treatment of these cysts, when symptomatic, is cyst-
plural or cyst—peritoneal shunting.
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Use ofthe syringoperitoneal shunt in the treatment of syringomye-
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Horn YE. Treatment of syringomyelia by syringoperitoneal shunt.
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Suzuki M, Davis C, Symon L, Gentili F. Syringoperitoneal shunt
for treatment of cord cavitation. J Neural Neurasurg Psychiatry
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Acta Neura Scand 1969;45:403-417.
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1983;58:188-197.
J Neurasurg

CHAPTER 18
Princi les 0fNeur0surgery,
edits by RobertG. Grossman. Rosenberg © 1991.
Published by Raven Press, Ltd., New York.
Vascular Malformations of the Spinal Cord
Lee H. Monsein and R. Nick Bryan
Overview, 387
Vascular Anatomy of the Spinal Cord, 387
Arterial System, 387
Venous System, 390
Imaging of Spinal Cord Vascular Malformations, 390
OVERVIEW
Spinal vascular malformations (SVMs) were reported as
early as 1888 by Gaupp, who described what was proba-
bly a dural spinal arteriovenous malformation (1). In
1900 Brasch precisely described this type of lesion (2),
and in 1910 Krause performed the first surgical exposure
of an SVM (3). However, it was not until 1916 that Els-
berg successfully removed an SVM with clinical improve-
ment (4). The preoperative myelographic diagnosis of an
SVM was made by Perthcs in 1926 (5). In 1953 Henson
and Croft opacified an SVM angiographically (6). Endo-
vascular embolization of SVMs was first performed by
Doppman, Di Chiro, and Ommaya (7) and by Newton
and Adams (8) in 1968, and it was extensively described
by Djindjian a few years later (9).
For conceptually simple lesions, SVMs have, until re-
cently, eluded definitive characterization, and they are
still among the most challenging neurosurgical lesions.
The diagnosis and treatment of SVMs represent an ex-
cellent example of the interdependence of neurosurgery
and neuroradiology in defining the pathophysiology of
the lesions and in implementing their subsequent treat-
ment.
Classification of SVMs was initially based upon de-
scriptive pathological analyses (10, 1 1). Subsequent classi-
fication was based upon selective spinal angiography
(12,13). In more recent years, refinement of angio-
graphic and microneurosurgical techniques has allowed
L. H. Monsein and R. N. Bryan: Division of Neuroradiol—
ogy, Russel H. Morgan Department of Radiology and Radio-
logical Science, Johns Hopkins University, Baltimore, Mary-
land 21205.
387
Clinical Aspects of Spinal Cord Vascular
Malformations, 393
Dural Spinal Arteriovenous Malformation, 393
Intradural Spinal Arteriovenous Malformation, 394
References, 397
a clearer understanding of the various types of SVMs
and a classification schema that stresses the pathophysiol-
ogy of these lesions.
Spinal vascular malformations can be divided into
two groups (14-17) (Table 1). Dural spinal arteriove-
nous malformations (DSAVMs) are defined as lesions in
which the abnormal arteriovenous shunt is embedded in
the dura covering the proximal nerve root and in the
adjacent spinal dura. Some believe that this abnormal
focus represents a single abnormal arteriovenous chan-
nel or fistula (18,19), whereas others propose the exis-
tence of a true arteriovenous malformation nidus
(14,19). In all likelihood both abnormalities can occur.
There is usually a single feeder vessel, which is a dural
branch of the radicular ramus of a lumbar or hypogastric
artery, and a single arterialized tortuous draining vein.
Intradural spinal arteriovenous malformations
(ISAVMs) are lesions in which the shunt ofthe abnormal-
ity is internal to the dura and involves the spinal cord or
is subpial. They are subclassiﬁed as a "nidus" type when
there is a vascular nidus present within the parenchyma
of the spinal cord or beneath the pia, and as a "fistula"
type when there is a direct fistulous connection without
an intervening nidus of abnormal tissue. These lesions
are fed by one or more abnormal arteries that may derive
from the anterior or posterior spinal arteries themselves
and which can have one or more draining veins.
VASCULAR ANATOMY OF THE SPINAL CORD
Arterial System (12,13,20—22)
The blood supply of the spinal cord is derived from
two sources: the vertebral arteries and the radiculomed-

388 / CHAPTER 18
TABLE 1. Classiﬁcation of spinal vascular ma/formations
Dural spinal arteriovenous malformations
Fistula/nidus
lntradural arteriovenous malformations
Nidus type
Fistula tvpe
ullary arteries (Figs. 1 and 2). Rostrally, the fourth por-
tion of each vertebral artery contributes to the formation
of a single anterior spinal artery. That fourth portion or
its branches also yield one or two smaller posterior spinal
arteries.
The posterior spinal arteries run approximately paral-
lel to one another in a somewhat tortuous fashion, just
medial to the dorsal root entry zone. They extend from
the upper cervical cord to the conus, where they curve
anteriorly to anastoinose with the anterior spinal artery.
These arteries may be discontinuous in their course, par-
ticularly in the thoracic region. The anterior spinal ar-
tery runs in a straight course from the upper cervical
cord to the conus level, where the anastoinosis with the
posterior spinal arteries occurs. Its length is formed by a
series of segments that are wider at the site of insertion of
the radiculomedullary arteries. It is variably attenuated
and may even be discontinuous, particularly in the
inidthoracic region.
Radicular arteries originate from spinal branches of
the dorsospinal rami of the vertebral, ascending cervical,
deep cervical, thyrocervical, costocervical, posterior in-
tercostal, lumbar, iliolumbar, lateral sacral, and median
sacral arteries. They pass medially through the l11tC1'V€1‘-
tebral foramina along with the nerve roots. Most of the
radicular arteries terminate by supplying the nerve roots.
Those that do reach the spinal cord branch into either
FIG. 1. Overview of spinal cord blood sup-
ply. (Adapted from reference 22.)

Vertebral body
VASCULAR MALFORMATIONS / 389
Penetrating
branches
of pial plexus
FIG. 2. Regional spinal cord arterial anatomy (from anterior): (1) posterior intercostal artery; (2) dorso—
spinal artery; (3) dorsal artery; (4) spinal artery; (5) anterior radiculomedullary artery; (6) posterior radicu-
lomedullary artery; (7) anterior spinal artery; (8) posterior spinal artery: (A) territory supplied by central
sulcal artery; (B) territory supplied by central sulcal artery and pial arterial plexus; (C) territory supplied by
pial arterial plexus.
anterior or posterior radiculomedullary arteries. Two to
14 anterior radiculomedullary and 6 to 23 posterior ra-
diculomedullary arteries reach the dura mater, where
they give off meningeal branches (supplying the periph-
eral pial plexus). They then divide into larger descending
and smaller ascending branches that contribute to the
anterior and posterior spinal arteries. There is often con-
siderable asymmetry at a single level, even though there
is an overall balance ofblood supply in each region ofthe
cord.
The arterial supply of the spinal cord can be divided
into three regions: the cervical (C 1 to T2), midthoracic
(T3 to T7), and thoracolumbar (T8 to conus) regions.
Although variable, the cervical portion of the anterior
spinal artery usually receives contributions from the ra-
diculomedullary arteries originating from the vertebral
artery at the C3 level, the deep cervical artery at the C6
level, and the costocervical trunk or superior intercostal
arteiy at the C8 level. The cervical portion of the poste-
rior spinal arteries generally receives one, although occa-
sionally bilateral, radiculomedullary contributions at
each level.
The midthoracic region has a relatively poor blood
supply. The anterior spinal arteiy usually receives only
one contribution from a right or left posterior intercostal
artery at the T4 or T5 level. There may be no contribu-
tions to the posterior spinal aiteries from T3 to T5. Be-
low the T4—T5 level there is an average of one posterior
radiculomedullary artery with eveiy other segment
down to the level of the conus.
The thoracolumbar portion of the anterior spinal ar-
tery derives its blood supply predominantly from a single
radiculomedulla1'y artery between the T5 and L4 levels
(arising from T9 to L2 in 62 to 85 percent, on the left in
73 to 80 percent). This artery is called the artery of
Adamkiewicz, arteria radiculomedullaris magna, or the
artery of the lumbar enlargement.
The intrinsic blood supply of the spinal cord can be
divided into two parts. The central (centrifugal) system is
represented by the central arteries originating from the
anterior spinal artery. The peripheral (centripetal) sys-
tem consists of numerous small arteries that originate in
the pial network covering the spinal cord. The pial
plexus is formed by tributaries of both the anterior and
posterior spinal arteries.
Blood from the anterior spinal artery is distributed to
the anterior two—thirds of the substance of the spinal cord
via the central branches and peripheral penetrating
branches. The central branches pass into the anterior
median fissure to supply the central parts of the sub-
stance of the spinal cord. At the anterior commissure,
the branches turn alternately from side to side to supply

390 / CHAPTER 18
both halves of the cord, except perhaps in the lumbar
enlargement where both branches may arise from a com-
mon trunk. These terminal branches may have a hori-
zontal, ascending, or descending course within the cord,
supplying overlapping territories. There are 4 to 9 cen-
tral arteries for each centimeter length of the spinal cord
in the cervical region, 2 to 6 in the thoracic region, and 5
to 12 in the lumbar region. The central arteries supply
the anterior commissure and adjacent white matter of
the ventral columns, anterior horns, bases of the poste-
rior horns, Clarke's columns, corticospinal tracts, spin-
othalamic tracts, ventral parts of the gracile and cuneate
fasciculi, and the region around the central canal.
Penetrating branches from the pial plexus supply the
posterior third of the spinal cord substance, which in-
cludes the outer portions of the posterior horns, most of
the posterior columns, and the outer portion of the white
matter of the periphery of the spinal cord. There is some
degree of overlap in the distribution of the peripheral
and central arteries at the capillary level, but they do not
anastomose at the arterial level; hence, both types are, in
effect, end arteries. Likewise, there is little functional
anastomosis between the anterior and posterior arterial
circulations of the spinal cord.
Venous System (12, 1 3,2 1 -23)
The spinal cord drains by two principal groups of in-
trinsic veins (Figs. 3 and 4). A central group collects
blood from the anterior horns and associated white mat-
ter and drains into the central veins in the anterior me-
dian fissure that, in turn, form the anterior median spi-
nal vein. A radial group arises from a capillary plexus at
the periphery of the dorsal and lateral white matter and
drains toward the surface to join the coronal plexus.
The coronal plexus is irregularly distributed around
the cord but tends to align in irregular columns, particu-
larly over the posterior median sulcus, the posterior in-
termediate sulcus, and along the line of the posterior
nerve roots. Branches of this plexus on the anterior and
ventrolateral parts of the cord drain into the anterior
median vein. The anterior median vein, which is fre-
quently a double structure, extends the length of the spi-
nal cord.
The superficial veins of the cord drain through medul-
lary veins that arise from the anterior median vein and
which accompany many of the nerve roots. Anteriorly
there are usually as many medullary veins as arteries.
The veins may be asymmetric, however, and not follow
the same course as the arteries. Posterior medullary veins
are more numerous. Medullary veins drain into the
plexus around the nerve roots in the intervertebral fora-
men and, in turn, into the paravertebral or epidural ve-
nous plexus, which connects with the vena cava, azygos,
hemiazygos, cerebral dural sinus, or cerebral venous sys-
tems.
Azygos
Ascending intervertebral
lumbar
Posterior
intercostal
FIG. 3. Overview of venous drainage of spinal cord.
Valves have been described in the medullary veins at
their junction with the coronal plexus and may help pre-
vent reflux of blood from the paravertebral plexus into
the spinal canal (13). Valves on the intrinsic veins proba-
bly also prevent reﬂux of blood from the surface of the
spinal cord (24).
The usual drainage of the dura of the cord and nerve
roots is probably toward the coronal system (17,18).
IMAGING OF SPINAL CORD
VASCULAR MALFORMATIONS
Spinal puncture is usually one of the initial diagnostic
procedures performed in a patient with a suspected
SVM. Only 20 percent of patients with an SVM will have
normal CSF; the remainder will usually have an elevated
protein level, averaging 100 to 150 mg/ml with a mild
pleocytosis of 6 to 50 cells. Fewer than 10 percent
will have xanthochromia or subarachnoid blood in
their CSF.

VASCULAR MALFORMATIONS / 391
Post, median
spinal v. Epidural v.
Coronal
venous Ant.‘median
plexus spinal V.
Vertebral body
FIG. 4. Regional spinal cord venous drainage (from anterior): (1) intervertebral vein; (2) anterior medul-
lary vein; (3) posterior medullary vein; (4) coronal venous plexus; (5) epidural venous plexus; (6) posterior
median spinal vein; (7) anterior median spinal vein.
Myelography is usually the next diagnostic procedure
performed. The examination is performed with a non-
ionic iodinated contrast material. The myelographic ap-
pearance of SVMs has been well described (25). The
myelogram will be abnormal in at least 90 percent of
cases; the percentage may approach 100 percent if a very
complete examination is done, including supine views.
In most cases, there will be obvious serpiginous filling
defects within the subarachnoid space, usually second-
ary to engorged draining veins (Fig. 5). In approximately
15 percent of cases, there may be suggestion of a partial
block associated with the serpiginous defects. The strik-
ing serpentine vascular defects at myelography are
usually most concentrated in the area ofthe nidus. How-
ever, abnormal vessels may extend throughout the
length of the spinal canal.
Myelography is highly accurate in making the initial
diagnosis. The radiographic differential diagnosis is li1n—
ited to partial block from other etiology with secondary
venous distention, vascular neoplasm such as heman—
gioblastoma, arachnoiditis, arachnoid seeding of neo-
plasm, and, rarely, hypertrophy ofthe cauda equina (De-
jerine—Sottas syndrome). Arachnoiditis is seen as
irregular linear filling defects within the contrast 1nate—
rial; however, these defects are usually not of the distinct
seipiginous vascular nature seen with SVMs. Arachnoid
neoplasm usually presents as more poorly defined globu-
FIG. 5. Nonionic iodinated myelogram in patien; with dural
fistula of midthoracic spinal cord with dilated vein (arrow) ex-
tending down to conus level, causing serpiginous filling de-
fect.

392 / CHAPTER 18
lar filling defects rather than curvilinear lucencies. A vas-
cular neoplasm such as hemangioblastoma may be im-
possible to differentiate frotn an SVM by myelography
alone. Myelography is certainly accurate for initially find-
ing the lesion and making the presumptive diagnosis.
Definition of the nidus and its blood supply requires angi-
ography.
Spinal angiography is the primary means of making a
conclusive diagnosis of SVM and is essential. Selective
spinal angiography is usually performed by the trans-
fetnoral approach. Usually, a four to six French polyeth-
ylene catheter with a relatively simple curve on the end is
utilized. The catheter tip is placed directly into the po-
tential feeding arteries, and an appropriate amount of
contrast material is injected in conjunction with serial
filming. At the present time, the contrast material of
choice is a low osmolality or nonionic iodinated agent
(Figs. 6 and 7).
Angiography is preferably performed under local anes-
thesia, which is usually feasible with adequate premedica—
tion and analgesic supplementation during the examina-
tion. Some neuroradiologists prefer to use general
anesthesia, particularly if they anticipate that the proce-
dure will be very long or that the patient will be uncooper-
ative. Selective injections are relatively painful, and anes-
thesiologists should not hesitate to ameliorate this with
intravenous medications. Filming can be done with con-
FIG. 6. Normal spinal angiogram—arterial phase (injection of
right T9 intercostal artery), demonstrating artery of Adamkie—
wicz (arrow).
FIG. 7. Normal spinal angiogram—venous phase, demon-
strating anterior median vein (arrow) coursing with anterior
spinal artery and azygous venous system (arrowheads).
ventional radiographic technique or with digital subtrac-
tion angiography. Arterial feeders are usually identified
in the first two to four seconds. However, late—draining
veins, which are clinically significant because they may
cause symptoms remote from the SVM itself, may be
seen several seconds later.
The neuroradiologist tnust inject all potential feeders
to the lesion. In the cervical area, potential feeders in-
clude the thyrocervical and costocervical trunks and
both vertebral aneries. In the thoracic region, the highest
intercostals off the aortic arch and the individual inter-
costals down through T1 2 should be studied. In the lu1n—
bar region, the lumbar segmental arteries through L4
and the hypogastric arteries may occasionally supply an
SVM. In the cervical region, all six potential feeding ves-
sels, and usually the highest intercostals, are selectively
injected. In the thoracic and lumbar areas, one usually
injects at least three segments above and below con-
firmed feeders to the angiotna. Because abnormal
feeders may be remote frotn the region of sy1npto1natol—
ogy, the blood supply of the entire spinal cord may have
to be studied before a lesion can be identified.
Although it is difficult, it is important to try to deter-
mine whether the lesions are dorsal, ventral, or within

the spinal cord. This is usually attempted with anteropos—
terior (AP) and lateral filming, but the procedure is cer-
tainly not definitive because extramedullary lesions may
wrap around the sides of the spinal cord and appear to be
intramedullary on the lateral films. AP stereoscopic
filming may help in delineating the intramedullary or
extramedullary location of the lesion.
Computed tomography (26) and, more recently, 1nag—
netic resonance imaging (MRI) (27-30) have been
shown to be useful in revealing the presence of a vascular
lesion of the spinal cord. However, these techniques do
not provide sufficiently detailed information concerning
the vascular anatomy and are therefore, at best, supple-
mentary procedures.
CLINICAL ASPECTS OF SPINAL CORD
VASCULAR MALFORMATIONS
Dural Spinal Arteriovenous Malformations
Dural spinal arteriovenous malformations (Table 2)
are the 1nost frequently encountered form of SVMs (14-
l9,3l—37). They are 1nost commonly found in the lower
thoracic or lu1nbar area, even though symptoms may be
localized to a remote level. It is hypothesized that these
lesions are acquired and that their related symptomatol—
ogy is due to abnormal spinal venous drainage resulting
in venous hypertension.
Males are affected about nine times more frequently
than females. Onset of symptoms can be at any age but is
most common at about the age of 50.
Most patients with DSA VMs experience gradual onset
and progression of neurological dysfunction. The dura-
tion of symptoms before diagnosis is less than three years
in about two—thirds of patients. The initial sy1npto1n is
most commonly spastic paresis of the lower extremities.
Symptoms at diagnosis may also include loss of pain and
temperature sensation, bladder dysfunction, impotence,
nerve root pain, and back or remote pain that is aggra-
vated by physical activity. Subarachnoid hemorrhage is
rare (38).
Physical examination reveals muscle wasting, abnor-
mal tendon reﬂexes, muscle fasciculations, and loss of
VASCULAR MALFORMATIONS / 393
abdominal reﬂexes. Spine radiographs are usually nor-
mal. Myelography demonstrates dilated and tortuous
vessels in the majority of cases and rarely a block. Re-
cently a few DSAVMs have been detected with MRI. In
these cases, spinal cord ischemic changes may be more
striking than the vascular lesion itself.
Selective spinal angiography usually shows a single
feeding vessel originating in the lower thoracic or lumbar
region (Figs. 8 and 9). The abnormal connection is most
commonly projected lateral to the spinal cord or, less
frequently, in an intervertebral foramen. Blood flow
through the lesion is usually slow (angiographic arterial
phase lasting six seconds or more), and arterial or venous
aneurysms are rare. The fistula or nidus itself appears as
an irregular conglomeration of small vessels. The dilated
tortuous medullary veins are almost always found on the
dorsal aspect of the cord. Venous drainage from the fis-
tula is slow and predominantly rostral, and it joins the
coronal venous plexus. Venous drainage fro1n the spinal
cord coronal plexus to the epidural plexus via the 1nedul—
lary veins is jeopardized, resulting in passive venous con-
gestion of the spinal cord.
Pathologically, ischemic necrosis of the affected areas
of the cord particularily involves the lateral corticospinal
tract, adjacent portions of the white matter of the lateral
funiculus, anterior gray, and posterior columns
(l0,l9,39—4l). The anteromedian segment is consis-
tently spared. In addition to the necrotic changes, many
new capillaries are seen, which are thought to represent
neovascularization secondary to prolonged ischemia.
Excellent results have been obtained in the treatment
of these lesions with endovascular embolization or sur-
gery. Embolization involves placing the tip of a catheter
as distal as possible in the feeding artery and introducing
an occluding agent such as cyanoacrylate glue (9,l8,
42-46).
Surgery requires a limited laminectomy in order to
expose the proximal aspect of the single abnormal arter-
ialized draining vein, which is doubly clipped and locally
excised. The nidus itself, which may appear as a bluish
discoloration of the dura, if accessible, may be
coagulated or excised, but it need not be (l4,l5,l9,
3l,32,47,48).
TABLE 2. Comparison of dural and intradural spinal arteriovenous malformations
Dural lntradural
Age 40-50 years Infancy and adolescence
Sex Males > Females 9:1
Etiology Acquired Congenital
Location Thoracolumbar > Thoracic Thoracolumbar > Thoracic > Cervical
Onset symptoms Gradual Rapid
Rare Common
Course
rapid attacks
Progressive with several
Spontaneous improvement and recurrence
of symptoms with long clinical course

394 / CHAPTER 18
Vertebral body
FIG. 8. Dural spinal arteriovenous malformation (from posterior).
FIG. 9. Dural fistula iarrow) with feeding artery (arrowhead)
and draining vein (open arrow).
Long—term resolution or improvement in sy1npto1n—
atology has been achieved with both forms of therapy.
Improvement can occur in a few days, and recurrence is
unusual. Clinical improvement occurs in the majority of
patients and is maximal in patients with less severe neu-
rological deficits.
Intradural Spinal Arteriovenous Malformations
Intradural spinal arteriovenous malformations
(ISAVMS) (Table 2) have been studied for many years,
but, because they were not considered separate from the
dural variety until recently, it is difficult to interpret
much of the relevant literature. A few recent reports,
however, describe the characteristics of ISAVMS and do
not combine them with DSAVMS (l4—l6,l9,49—53).
Intradural spinal arteriovenous vascular 1nalfor1na—
tions are less frequently found than DSAVMS, and there
is less of a male dominance. The distribution ofthe nidus
type of ISAVMS is more extensive along the longitudinal
axis of the spine, and more ISAVMs appear in the cervi-
cal area than DSAVMS. The location ofthe fistula type is
similar to DSAVMS. Associated extraspinal vascular
malformations, a somewhat uniform distribution along
the length of the spinal cord, abundant cranial and cau-
dal venous drainage, and a young age ofclinical presenta-

tion suggest that ISAVMs are congenital in origin.
Symptoms are due either to an arterial steal, since the
feeding vessels are medullaiy arteries, or to the sequelae
of high blood ﬂow causing aneurysms and bleeding.
Onset of symptoms is earlier with ISAVMs than with
DSAVMs, with an average age in the late twenties.
Symptoms from the nidus type typically occur in early
infancy to adolescence, and those from the fistula type
usually occur between 20 and 40 years of age.
About half of patients with ISAVMS experience acute
onset of initial symptoms, which is usually related to
either intramedullary or subarachnoid hemorrhage.
Hemorrhage is 1nore common in the nidus than the fis-
tula type of ISAVM. Symptoms and findings on physical
examination are similar to those for patients with
DSAVMs.
Spine radiographs may rarely show erosion of bony
structures, which may result in an increased pedicular
distance. Myelography usually shows one or more ser-
piginous vascular filling defects, occasionally a partial
block, and rarely a complete block. Intradural spinal arte-
riovenous malformations can be more easily detected
with computed tomography and MRI than DSAVMs.
Selective spinal angiography usually demonstrates a
high—flow lesion with more than one feeding artery aris-
ing from a combination of spinal and radicular arteries
(posterior more often than anterior). Venous drainage is
usually into more than one tributary of the coronal
plexus. If the ISAVM is a "nidus" type, the shunt ap-
pears as a tangle of vessels that is partially or totally
within the substance of the spinal cord (Figs. 10 and 11).
Vertebral body
VASCULAR MALFORMATIONS / 395i
If it is a "fistula" type, the shunt is most commonly pro-
jected anteriorly, outside the spinal cord (Figs. 12 and
13). Associated arterial or venous aneurysms are seen in
almost half of patients.
Intradural spinal arteriovenous malformations have a
much worse prognosis and are far less amenable to endo-
vascular embolization and surgical therapy than
DSAVMs because of IVASMs' closer proximity to nor-
mal neural tissue and its blood supply. An improvement
in neurological status is obtained in only about 30 per-
cent of patients with therapy. Nevertheless, significant
improvement can safely be obtained in many cases by
embolization alone (43,50,5l,54—58) or, more com-
monly, by embolization in combination with surgery.
If surgery is contemplated, one should understand
that the preoperative neurological status is often related
to the postoperative outcome. It is better to do surgery
early in the disease than to wait for the development ofj
major neurological deficits (15,19,59—64).
It may not be necessary to remove the entire malfor-
mation at surgery; instead, it may be sufficient to in-
terrupt the abnormal connections between the major ar-
terial supply and venous system. If, after a less extensive
procedure, the malformation remains turgid and the
veins contain arterialized blood under pressure, it may
be necessary to remove the entire malformation in-
terrupting even the smallest arterial contribution.
Microsurgical technique is usually used. A la1ninec—
tomy is centered over the extent of the lesion. Upon ex-
posing the lesion, the arachnoid is opened. Intramedul—
lary lesions are treated by myelotomy and techniques
Ant. spinal a.
Nidus of
vascular
malformation
FIG. 10. Nidus type of intradural arteriovenous malformation (from posterior).

396 / CHAPTER 18
FIG. 11. Intradural arteriovenous malformation (arrow) with feeding artery (arrowhead) and draining vein
(open arrow): (A) anteroposterior; (B) lateral.
Vertebral body
Radiculo-medullary a.
FIG. 12. Fistula type of intradural arteriovenous malformation (from posterior).

A B
VASCULAR MALFORMATIONS 397
C
FIG. 13. lntradural fistula (arrow) with feeding artery (arrowhead) and draining vein (open arrow): (A)
anteroposteriorthoracic region; (B) lateral cen/ical region—arterial phase; (C) lateral cervical region—ve-
nous phase. (From reference 49, with permission.)
similar to operation for intramedullary tumors. Only the
largest vessels are clipped, and a bipolar cauteiy is used.
The lesion is gradually peeled away from the spinal cord,
and additional arterial contributions are coagulated and
divided.
The operative mortality is very low. Morbidity is
usually related to additional temporary deﬁcits that, in
most cases, show improvement and eventually clear dur-
ing the postoperative period.
REFERENCES
1. Gaupp J . Hamoirhoiden der pia mater spinalis im gebiet des len-
denmarks. Beitr Pathol 1888;2:516-518.
2. Brasch F. Uber einen schweren spinalen Symtomenkomplex be-
dingt durch eine aneurysma-serpentinumartige Veranderung eines
Theils der Riickenmarksgefasse. Bert Klin Wochenschr 1900;37:
1210-1213.
3. Krause F. Clzirurgie des gelzirns and ruckenmarks naclz eigenen
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CHAPTER 19
Neural Tube Defects
Michael Pollay
Incidence, 399
Etiology and Embryology, 399
Pathology, 402
Natural History, 404
Clinical Presentation, 405
Myelomeningocele, 405
Occult Spinal Dysraphism, 406
Diagnostic Tests, 406
Prenatal, 406
Radiographic, 407
This chapter on spinal cord disease is limited to those
neural tube defects that are compatible with life and ame-
nable to medical and surgical therapy.
INCIDENCE
In the United States, the incidence of all forms of spi-
nal dysraphism is in the range of 0.7 to 1.0 per 1,000 live
births, although the incidence appears higher in the rnid—
eastern United States (1,2). This low incidence contrasts
with those of Celtic lineage in Ireland (approximately
4/ 1,000) and Wales (approximately 12/ 1,000). The open
variety of dysraphism is at least seven times greater than
the occult variety. The risk factor in mothers with
previously affected children is 40 to 50 per 1,000 and
rises to 100 per 1,000 with two such children. From the
standpoint of the individual mother, the percentage re-
currence rate usually quoted after the birth of one af-
fected sibling is 5 percent and includes cases of spina
bifida and anencephaly. The chance of producing a
dysraphic child after the birth of two afﬂicted children
increases twofold, to 10 percent (3). Probably half of the
children included in this group will be stillborn (4). Sig-
nificantly increased risks have been noted for mothers
M. Pollay: Neurosurgical Section, University of Oklahoma
Health Sciences Center, Oklahoma City, Oklahoma 73190.
399
Princi les of Neurosurgery,
edite by Robert G. Grossman. Rosenberg © 1991.
Published by Raven Press, Ltd., New York.
Urologic Evaluation, 409
Miscellaneous, 410
Indications for Surgery, 410
Operative Management, 410
Position, 410
Anesthesia, 41 1
Operative Observations, 41 1
Complications and Postoperative Care, 412
Results, 412
Outcome, 41 3
References, 41 3
over the age of 35 and for siblings of mothers who have
given birth to dysraphic children. In the male survivors
who do not have serious disabilities from their dysraphic
condition, about 35 percent produce children. In the
case of female survivors, up to 40 percent have children.
In either group, the incidence of neural tube defects in
their offspring is about 3 percent (4). These high recur-
rent risks suggest the importance of genetic counseling
and the survey of maternal serum and amniotic ﬂuid for
a—fetoprotein and acetylcholinesterase (4-6). There is re-
cent evidence that the occurrence of neural tube defects
is declining in certain parts of the world, including the
United States. This may in part be due to prenatal diag-
nosis, genetic counseling, and nutritional supplementa-
tion (5).
Spinal dysraphism, as a group of conditions, occurs
more frequently in the white population, and females are
affected almost twice as often as males (7). The lumbosa—
cral region is the site of the dysraphic lesion 80 to 90
percent of the time.
ETIOLOGY AND EMBRYOLOGY
The cause of myelodysplasia is unknown, although
there is evidence that both environmental and genetic
inﬂuences may affect neural tube development. For the
purposes of this discussion, it is important to understand

400 / CHAPTER 19
FIG. 1. Relationship of gestational age and the phases of
spinal cord development. (From reference 9.)
the alterations in normal development during various
embryologic phases that result in the clinical expression
of the dysraphic condition (8,9). The development of the
neural tube is presented graphically in chronological
order in Figure 1. The ﬁrst phase is called neuiulation; it
begins with the development of the neural plate and ter-
minates with the closure of the posterior neuropore at a
gestational age of somewhat less than 30 days. The ce-
Caudal cell mass
(site of canalization)
Vacuoles
differentiate
phalic end of the tube closes a few days earlier, and the
cavity thus formed represents the primitive ventricles,
which are in continuity with the central canal of the spi-
nal cord. One would not expect the spinal malforma-
tions that occur during this period to be covered by in-
tact skin. Furthermore, since the location of the closure
of the neural tube (posterior neuropore) is at the ﬁrst or
second lumbar segment, one would expect to find mal-
formations occuiring during this embryologic period ei-
ther at this level or above.
One of the more popular theories proposed to explain
the origin of open defects of the neural tube is Gardner's
(10). His hydromyelia theory suggests that the neural
tube closes normally in most of the open dysraphic prob-
lems but that reopening or rupture occurs because of the
distension of the central canal of the spinal cord, second-
aiy to failure in the development of the outlets from the
fourth ventricle, resulting in the prolongation of the
transient hydrocephalus that occurs as a normal phase in
development. In severe cases, an embryonic syringo—
myelocele will develop prior to rupture of the neural
tube. The same forces, according to Gardner's theory,
could cause impaction of the hindbrain into the upper
cervical region, while in less severe cases hydrocephalus
and/or cystic dilatation of the fourth ventricle could re-
sult. Patten proposed that the development of a myelo-
cele is secondary to overgrowth of the neural tube that
prevents complete closure of the tube (1 1). The hypothe-
sis that open neural tube defects are caused by nonclo—
sure of the neural tube has gained support based on ob-
servations in human embryos, although Lemire has
suggested that a small number of cases result from re-
opening of the closed neural tube (8). At the present
time, based on the wide range and frequency of central
nervous system anomalies associated with spina bifida
apeita, it is reasonable to conclude that neither the over-
growth, traction, nor hydrodynamic theory fully ex-
plains the full spectium of pathological features seen
with this condition (12).
The last two phases of neural tube development that
occur after closure of the posterior neuropore result in
elongation of the neural tube by the processes of canali—
FIG. 2. The processes involved in the
second phase of caudal neural tube
Conn ct with
6 development. (From reference 9.)
neural tube

30-mtn CR 67-mm CR
(Stage XXIII)
Ventriculus
terminals
Central
canal
Dura
V t . I Filum
en _”C”_ “S terminale
terminalis
Coccygeal medullary Vestige
FIG. 3. The relationship of the structures that develop during
the last phase (retrogressive differentiation) of caudal neural
tube development. (From reference 9.)
zation (Fig. 2) and retrogressive differentiation (Fig. 3).
These processes result in the development of the lower
lumbar and sacrococcygeal segments of the completed
neural tube (13). The canalization phase proceeds from
day 13 to 16 of gestation. The anlagen of the lower cord
segments consist of undifferentiated cells arranged
around vacuoles (Fig. 2). The vacuoles enlarge, coalesce,
and ultimately make contact with the long portion of the
tube previously formed during neurulation. The last
phase is retrogressive differentiation and consists pri-
marily of necrobiosis. The caudal cell mass regresses into
the ventriculus terminalis (the only grossly identifiable
NEURAL TUBE DEFECTS / 401
remnant of the caudal central canal), filum terrninale,
and Coccygeal rnedullary Vestige (13). Tlre filurn be-
comes fibrous, although it may contain ependymal or
ganglion cells. It also ultimately pursues an extradural as
well as intradural course. At birth, the level of the conus
is about L3, but because of the more rapid growth ofthe
vertebral column it lies at approximately the adult level
of LI—2 by two months after birth (Fig. 4) (14,15).
The spinal malformations occurring during these last
two phases of neural tube development are covered with
intact skin and display a wide variety of conditions
usually included in the general classification of occult
spinal dysraphism (Figs. 5 and 6). The mechanisms in-
volved in the development of most of these spinal mal-
formations are poorly understood, although the persis-
tence of a split notochord may reasonably explain a wide
variety of visceral and central nervous system defects
(e.g., pre— and postvertebral enteric cysts, butterﬂy verte-
brae, and splitting or duplication of the spinal cord). The
split notochord syndrome was first described by Bentley
and Smith (16). They theorized that the notochord de-
velops in duplicate, allowing a transient or permanent
connection (neurenteric canal) to exist between the dor-
sal surface of the embryo and the embryonic gut. A wide
variety of endodermal, mesodermal, and ectodermal
rests might be expected to reside along the course of this
defect, which would explain not only the enteric cysts
mentioned above but also the splitting of the cord by a
median septum (diastematomyelia) and the intraspinal
presence of certain congenital tumors [Figs. 5(B) and
6 (4)].
Age in Years
FIG. 4. The vertebral level of the conus medullaris at various ages as measured from magnetic reso-
nance images of the spine. (From reference 15.)

402 / CHAPTER 19
FIG. 5. Variety of common dysraphic conditions. (A) Typical myelomeningocele with neural plaque (1)
and nerve roots (2) attached to the external membrane sac; (B) pre— and postvertebral enteric cysts (1
and 3) communicating by means of residual enteric canal (2) through body of vertebra. Bony diastometa—
myelic septum (4) at lower end of split spinal cord; (C) lipomyelomeningocele (2) beginning beneath area
of hypertrichosis and extending into caudal end of spinal cord by way of a dural defect. The transverse
dural band (1) is shown to illustrate the potential compressive effect of this type of lesion.
FIG. 6. Tethering of spinal cord by thickened filum terminale
(1), with lipomatous inclusion (2), aberrant nerve roots (3), and
external dural band (5). Example of intradural tumor (dermoid,
epidermoid) in continuity with dermal sinus and dimple (4).
PATHOLOGY
The most common dysraphic defect is the absence of a
portion of the posterior elements of the spinal vertebrae.
In most cases, spina bifida occulta is of no clinical im-
portance and is observed as an incidental finding on
plain x—rays of the spine. It should be appreciated, how-
ever, that this usually hidden defect is very often asso-
ciated with other defects of the intraspinal contents.
The most common clinically significant neural tube
defect is the myelomeningocele (meningomyelocele,
spina bifida cystica, or aperta), which has been defined as
a defect in the dorsal elements ofthe vertebrae, accompa-
nied by herniation of the spinal cord and nerve roots into
a cystic swelling on the surface of the back [Fig. 5A]. This
lesion arises during neurulation, between the 17th and
30th gestational days (8). It is possible to classify this
defect into nine subcategories, depending on the actual
contents of the herniated sac (17). For most purposes,
however, the more general deﬁnition is sufficient to un-
derstand the clinical implications of the condition and
the therapeutic possibilities. This group of nervous sys-
tem defects is often associated with malformations of the
brainstem and the early potential for developing hydro-
cephalus. Other abnormalities associated with myelome-
ningoceles include, along with hydrocephalus and the
Arnold—Chiari malformation, dysplasia of the cranial
nerves, agenesis of the corpus callosum, and cortical and
cerebellar dysplasia (12).
A more uncommon condition presenting at the body
surface is the meningocele. In this instance, the cystic

F|G.7.MR|d spinal cord tethering due to a thickened filum
terminale. Aroiv at site a‘ dorsal hub dura.
swelling is formed by dura and arachnoid, while the ner-
vous tissue remains within the spinal cord. A simple
meningocele will often be connected to the intraspinal
space by a narrow stalk emerging from a single spine.
The bony defects are usually small and not palpable, and
there occasionally may be virtually complete covering
of the lesion with skin. The term meningocele manque
has been proposed to describe those meningocele lesions
that are small and present little evidence of their exis-
tence externally but have a loop of recurrent nerve roots
or spinal cord tracts adherent to the internal surface of
the dura mater (1 1). The wide variety of abnormalities in
NEURAL TUBE DEFECTS / 403
the central nervous system and other organ systems ob-
served in myelomeningocele patients is rarely encoun-
tered with the usual meningocele defect.
The occult spinal dysraphic conditions are less com-
mon but just as important as the previously described
open defects. They present the greatest diagnostic chal-
lenge because they are often hidden by the intact overly-
ing skin. This group exerts its effect on spinal function by
traction and/or compression on the spinal cord. The
most common pathologic entities in the occult group are
those malformations that interfere with the normal ceph-
alad migration of the spinal cord during the dispropor-
tionate growth of the vertebral column. The fixation of
the spinal cord can be due to an abnormally thickened
filum terminale that is tethered to the inner surface of
the dorsal dura mater [Figs. 6 (1), and 7]. The filum
under these conditions may contain ganglion cells and a
generous vascular bed. There also may be considerable
lipomatous infiltration of the thickened filum [Figs 6 (2)
and 8]. Extradural extensions of these bands do occur
and may be in continuity with a dermal stalk to the skin
surface [Fig. 6 (4) and (5)].
Another malformation that produces fixation of the
spinal cord is diastematomyelia [Fig. 5 (B4)]. By defini-
tion, this is a congenital anomaly in which the spinal
cord or the filum terminale or both are split dorsoven—
trally into two parts, usually separated by a septum. The
septum may be fibrous, cartilaginous, or bony and gener-
ally extends from the dorsal surface of the vertebral body
(Fig. 9). Such septa are most commonly seen in the tho-
racic region and may be associated with intraspinal neur-
enteric cysts as well as other bony anomalies (e.g., but-
terﬂy vertebrae, interlarninar fusion, or spinal bifida).
Unlike the duplicated spinal cord (diplomyelia), the cord
FIG. 8. A—P (A) and lateral (B) MRI of spinal cord tether-
ing due to thickened filum terminale with an intraspinal
B lipoma (arrow).

404 / CHAPTER 19
FIG. 9. MRI of diastematomyelia with septum (arrow).
"halves" in diastematomyelia are generally unequal in
size and cellular content (18). In approximately one—half
the cases, the dura is duplicated. In most instances, the
cord above and below the split is normal. Generally the
dividing septum is at the lower limits of the split cord. In
a number ofcases, the septum has been found at a consid-
erable distance from the lower end of the divided spinal
cord (19). In those instances where no septum is present,
the tethering effect on the spinal cord results from bands
between spinal cord and dura, either at the split end or
more distally at the conus.
In the frilly developed split notochord syndrome, in-
traspinal and mediastinal foregut cysts may also be pres-
ent. The intraspinal cysts may occur without the diaste—
matomyelic defect and produce a neurologic deficit by
means of direct spinal cord compression. Compression
syndromes are also seen with transverse dural bands
[Fig. 5 (Cl)] and intraspinal tumors (epidermoid, der-
rnoid, and teratomas) [Fig. 6 (4)]. These masses may
have extradural extensions by means of a dennal or fi-
brous tract and may occasionally produce distortion at
the skin surface [Fig. 6 (4)]. A somewhat more frequent
malformation in the mass effect group is the lumbosa-
cral lipoma [Fig. 5 (C2)]. It is thought that these lesions
produce their effect by traction as well as compression.
The passage of these subcutaneous, benign fatty tumors
through the dura into the spinal cord and/ or roots inter-
feres with neural conduction by causing traction during
childhood growth (11). In addition, the intra— and extra-
dural lipoma may cause a mass effect on the involved
neural tissue (20). These intradural extensions of fatty
tissue are properly called lipomyelomeningocele when
there is an associated cystic cavity within the mass. All of
these lesions may on occasion be, connected to the over-
lying skin by a tract.
NATURAL HISTORY
Meningoceles and myelomeningoceles are usually ap-
parent at birth. The neurologic deficit, if present, is
usually well developed. Even when the myelomeningo-
cele is repaired, the patient may later deteriorate neuro-
logically owing to a tethered cord Gjig. 10) (21). The of-
ten associated hydrocephalus may not be apparent at
birth, but usually appears before the third year. When
untreated, this leads to progressive enlargement of the
skull, with associated neurologic dysfunction. The clini-
cal course is often dictated by the associated anomalies.
According to a study by Laurence and Tew, 25 percent
of the myelomeningocele infants are stillborn, and 13
percent die within the first week (13). Untreated, another
47 percent die from complications of this condition;
only 9 percent of those untreated were still alive during
the sixth year of their study. In the United States, Shurt—
leff reported that 23 percent of his untreated group lived
until 6 to 10 years of age (3). Early death generally results
from increased intracranial pressure secondary to hydro-
cephalus or from central nervous system infections, al-
though other severe associated anomalies within and
outside of the nervous system may be responsible as well.
The late mortality is generally caused by urinary tract
dysfunction and infections, as well as the complications
of hydrocephalus. The later cause of death has often
been sudden and is presumably a result of the acute ob-
struction of ventricular shunts or of pulmonary embo-
lism in the case of ventriculovascular shunts (22).
The natural history of concealed dysraphic conditions
is substantially different. These lesions are often not ap-
FIG. 10. Lateral view MRI of tethering following a myelome-
ningocele repair (arrow).

predated at birth because of the intact skin. The develop-
ment of clinical dysfunction is usually delayed and insidi-
ous in onset. In some series, almost 90 percent of the
patients develop significant defects in function in the
lower extremity or of the bowel and bladder (23). In
many instances, once developed, these defects are not
reversible by any therapy (24). There is little question
that, in terms of the natural history of the open and
closed dysraphic lesions, the former is less a challenge in
diagnosis than in treatment, whereas the reverse is true
of the latter.
CLINICAL PRESENTATION
Myelomeningocele
The diagnosis at birth is based on the appearance of
the external cystic lesion, which contains the externally
placed plaque of neural tissue with varying degrees of
intact skin [Fig 11(A)]. Most of these lesions are in the
lumbar region, with the remaining cases found primarily
in the lower thoracic and upper sacral areas. These le-
sions may, however, occur anywhere along the neuraxis.
Deformity of the spine is common and includes widened
pedicles in the region of the spina bifida, as well as ky-
phosis and scoliosis. Severe deformities are found in 5 to
10 percent of patients and are often caused by muscle
imbalance not associated with vertebral body abnormali-
ties. In more than half the cases there is obvious limb
deformity at birth. As expected, the degree of neurologic
deficit is generally related to the site of the lesion. The
lower the lesion is, the more restricted the neurologic
deficit. Unfortunately, only 10 percent or fewer of the
lesions are found in the sacral region. The clinical mani-
festations, in a general sense, reﬂect the level of the defect
as follows. Lesions at or above the thoracolumbarjunc—
tion result in a ﬂaccid paraplegia without hip dislocation
or limb deformity because there are no deforming forces
present. Involvement of the lower lumbar segments re-
sults in preservation of hip ﬂexors and abductors, but
weak or absent extensors, and abductors with no useful
A B
NEURAL TUBE DEFECTS / 405
function at the knee or ankle. As a result of unopposed
muscular activity at the hip, dislocation at this joint is
common. With low sacral myelomeningocele, the deficit
may involve only the ankle or movements of the distal
foot (25). In the newborn, complete evaluation of the
motor system is difficult, but, on close observation, re-
ﬂex movement sometimes can be separated from volun-
tary or purposeful activity. Observing the response to
pulling or extension of the extremities and to superficial
sensory stimulation will often lead to a useful evaluation
of the motor level of the lesion. These lesions may be of
the upper or lower motor neuron variety. Unfortunately,
the motor levels do not always correlate well with the
sensory loss or the radiographic definition of abnormal
vertebra (3).
Altered function of the bowel and bladder is difficult
to evaluate at birth and represents the greatest threat to
early and late survival (1,26). The presence of an anal
wink has little significance in terms of indicating a func-
tional anal sphincter. The tone of a grossly patulous anus
usually will increase with time and often is associated
with rectal prolapse. The spastically tight anal sphincter
can be determined at birth, but, along with the lax
sphincter, functional evaluation of control at birth re-
mains difficult. Evaluation of bladder function is also
impossible, but a large palpable bladder indicates an in-
creased urinary sphincter tone with an associated high
resistance to emptying by abdominal compression. The
opposite might be seen in the case of a sphincter with
little tone.
Most infants with myelomeningocele are afflicted
with the Arnold—Chiari malformation, and it is therefore
not surprising that this potential compromise in the out-
flow of cerebrospinal ﬂuid from the ventricular system
and/or the basal subaraclmoid space results in a high
incidence of hydrocephalus. In addition, this brainstem
malformation may result in a failure to thrive owing to
breathing and swallowing difficulties, progressive spastic-
ity, and upper extremity weakness (27). The incidence
and severity of the hydrocephalus is related to the site of
the lesion. In most series, 15 to 20 percent of infants with
a myelomingocele present with hydrocephalus at birth.
C D
FIG. 11. (A) Large upper lumbar myelomeningocele; (B) dermal sinus, low lumbar, with two skin dimples
above this level; (C) tail—like structure, hypertrichosis, and subcutaneous lipoma; (D) small foot in occult
spinal dysraphic patient.

406 / CHAPTER 19
Another 40 to 60 percent develop this complication
within three years, although in most it is apparent within
the first month of life (28). A large number of hydroce-
phalic infants have aqueductal stenosis, which may be
secondary to the compression of the tectum by the di-
lated lateral ventricles. Since a relatively small number
of hydrocephalic infants are observed at birth, one nor-
mal head measurement has no predictive value. Serial
measurements must be made to evaluate properly the
early development of hydrocephalus. In this regard, pre-
mature infants may have significantly large changes in
ventricular size with little or no change in the measured
head circumference (28). It is important to examine
these infants for malformations in other organ systems:
polydactyly, limb bone hypoplasia, fused ribs, defects in
the heart, and overt or hidden anomalies ofthe genitouri-
nary system (3,4).|
Occult Spinal Dysraphism
As mentioned earlier, the diagnosis ofthese conditions
is often missed until a definite and often irreversible or-
thopedic or urologic syndrome develops, since these
postneurulation lesions are covered with skin (9). In
about half of the cases, however, there are cutaneous
manifestations that act as sentinels for malformations of
bone and nervous tissue deep beneath the skin surface.
Some of these are shown in Figure 11 and include, in
order ofdecreasing frequency, the following: lipoma, hy-
pertrichosis (hairy patch), dermal dimple or sinus, pig-
mented macule, vascular nevus, and a tail—like cutane-
ous appendage. In a significant number of cases there is a
combination of these cutaneous stigmata. In most in-
stances, recognition of these spinal malformations prior
to the development of clinical syndromes will depend on
recognition of the skin lesions by an astute observer. It
should be appreciated that a sacrococcygeal dermal sinus
(pilonidal sinus) usually terminates in an extradural lo-
cation, although sorne dermal sinuses with intraspinal
communications have been reported (29). Those occur-
ring cephalad to the lumbosacral region should be
viewed with a high index of suspicion, and the patient
should be evaluated to exclude intraspinal pathology
(30,31). Awareness of the association between an imper-
forate anus and sacral bony and neurologic abnormali-
ties is also important since the associated neurologic le-
sions have been shown to be progressive as a result of
tethering of the lower cord and/or bony and dural steno—
sis (32).
In general, the onset of the spinal dysraphic syn-
dromes occurs in childhood, but they are often accen-
tuated during adolescence. In some instances, however,
the clinical manifestations arise initially in the adult.
Two major clinical syndromes are associated with these
spinal malformations, although very often a combina-
tion is seen. In the orthopedic syndrome there is usually
present an asymmetry of the legs, because of a predomi-
nant unilaterally diminished muscle bulk, and a short
foot [Fig ll(D)]. The foot is often inverted, with a high
arch and clawed toes. The skin of the plantar surface of
the foot may show trophic ulcers. The deep tendon re-
ﬂexes in the involved extremity may be absent in the
presence of an extensor—plantar response. The sensory
loss may be quite variable, but generally involves the low
lumbar and sacral segments asymmetrically. The exter-
nal examination of the spine (excluding cutaneous man-
ifestations) may be quite normal, although scoliosis and
kyphosis are sometimes seen. The level and complete-
ness ofthe neurologic abnormalities are generally related
to the location as well as the extent of the malformation.
The urologic syndrome may present itself early by the
complaints of bed—wetting or frequent urinary tract in-
fections (24). Often these complaints are preceded by a
history of a normal voiding pattern.
The varied manifestations of deficits produced by
these occult spinal malformations emphasize the impor-
tance of the roles played by the pediatrician, urologist,
and orthopedist in the early diagnosis of these syn-
dromes (33).
DIAGNOSTIC TESTS
Prenatal
Prenatal tests are increasingly used in high—risk par-
ents to rule out significant dysraphic defects in the fetus
(4,34). A number of methods of diagnosis are used in-
cluding ultrasonography, fetography, fetoscopy, and bio-
chemical analysis of the maternal serum and amniotic
ﬂuid. The latter analysis is based on the observation that,
in some children with neural tube defects, there is an
increase in a—fetoprotein (AFP) in the amniotic ﬂuid.
The main source of this chemical marker is the fetal ur-
ine; it is synthesized in normal embryonal liver cells, the
yolk sac, and the intestinal tract. The concentration of
this marker is maximally different in the dysraphic fetus,
as compared with the normal fetus, between 14 and 16
weeks of gestational age. The normal value of 25 Mg/rnl
may be elevated up to tenfold in the dysraphic fetus.
Failure to detect dysraphic conditions with this test can
occur, owing to skin—covered lesions or amniotic ﬂuid
samples taken late in pregnancy. Elevated levels of this
marker resulting from dysraphic conditions can also be
seen in maternal serum, although similar elevations have
been reported in benign and malignant liver disease. The
presence of an open dysraphic lesion should be con-
firmed by ultrasonography when this marker is elevated.
A complementary test to AFP assay is the measurement
of acetylcholinesterase (AChE) in the amniotic ﬂuid.
The presence of elevated levels of both AChE and AFP

will reduce the already small percent of false results with
either test alone (5).
Radiographic
Among the earliest studies to be obtained in dysraphic
conditions are anteroposterior (AP) and lateral radio-
graphs of the spine. The most common anomaly to be
found is spina biﬁda, which may be related to the site of
the neural lesion. The most obvious and gross changes in
the posterior elements of the vertebrae are seen in the
open dysraphic conditions (myelomeningocele), as are
the most severe kyphotic and scoliotic deformities.
In patients with a myelomeningocele, scoliosis may be
observed extending over a great number of vertebrae,
with associated fused ribs and kyphosis. In addition, in-
formation derived from routine and contrast radio-
graphic studies is used to evaluate cardiopulmonary,
musculoskeletal, and urologic abnormalities. These le-
sions may be in the form of cardiac septal defects, hip
dislocation, urinary reﬂux, and hydronephrosis. Routine
contrast myelography, computed tomography (CT), or
magnetic resonance imaging (MRI) probably has little or
no role in the initial evaluation of open neural tube de-
fects, although these diagnostic modalities can be impor-
tant in evaluating delayed complications owing to Ar-
nold—Chiari malformation, syringohydromyelia, and
postmyelomeningocele tethering (Figs. 10 and 12)
(35,36).
Routine radiographs of the spine may be normal in
some cases of occult dysraphism. Usually, however,
there will be evidence of skeletal anomalies, such as de-
fects in the posterior elements of the vertebrae (spina
FIG. 12. Lateral view MRI of Arno|d—Chian malformation
(small arrow) and cervical syringomyelia (large arrow).
NEURAL TUBE DEFECTS / 407
bifida), malformed or fused laminae, a widened spinal
canal [Fig. 13(A)], or bony median vertebral septa [Fig.
l4(A and B)]. These bony abnormalities are more pre-
dictive of the site of the intraspinal pathology than are
cutaneous signs (19). Usually, the midline bony spurs
seen in diastematomyelia are difficult to visualize in rou-
tine films and are appreciated only by linear tomography
of the suspected area of involvement. The combination
of intersegmental laminar fusion and spina bifida often
suggest the level of the diastematomyelia (19). The most
definitive radiographic studies utilize a contrast sub-
stance or computed imaging (CT or MRI). In recent
years the contrast agents generally have been of the
water—soluble variety so that linear tomography can be
easily combined with computed tomography during the
same visit to the radiology department. Perfectly accept-
able films, however, can be obtained with air as the con-
trast substance. The latter can also be combined with a
CT study. Approximately 50 to 60 ml of air is used, but
infused in increments of 10 ml with the patient in a 20-
degree Trendelenburg position. Both air and water—solu-
ble contrast substances generally require the use of linear
tomography for the best definition. Water—contrast me-
dia offer the best overall advantages including denser
images than obtained with air, easy combination with
linear and computed tomography, and lack of need to
remove (as compared to oil) at the end of the study. In
most cases, myelography is performed under local anes-
thesia supplemented with intravenous diazepam. The
total volume of the water—soluble agent (metrizamide)
used is in the range of 6 to 14 ml, at a concentration of
190 mg of iodine per ml. Complications, which may in-
clude headache, vomiting, and/or seizures, are infre-
quent if the patient is properly hydrated and drugs that
lower seizure threshold (phenothiazine derivatives) are
avoided. Recently, newer non—ionic water—soluble con-
trast agents (e.g., iohexol) have been introduced which
produce fewer side effects and which do not require pre-
medication.
In those patients in whom a mass lesion is suspected in
the lumbar region, it might be prudent to inject the con-
trast agent into the cisterna magna or into the cervical
subaraclmoid space by means of a lateral cervical punc-
ture. Following the instillation of the contrast medium,
the spinal needle is removed and the patient placed in
the supine position for the myelographic study. The CT
scan then follows completion of the myelogram. To
diagnose a tethered conus medullaris, it is necessary to
visualize clearly the lowest point of the conus in order to
relate it to the vertebral level (Fig. 7). The vertebral level
at which the normal conus is found at various times fol-
lowing birth, based on MR imaging of the spine, is pre-
sented in Figure 4. MRI appears to be the radiographic
procedure of choice not only for localization of the
conus but for most intraspinal abnormalities (35). The
size and the site of attachment of the filum or other

408 / CHAPTER 19
A B
D
FIG. 13. (A) Wide lumbar canal with defects in lamina at low lumbar level; (B) myelographic evidence of
cystic intraspinal Iipoma (lipomyelomeningocele); (C) CT cross—section through lipoma (arrow) passing
into spinal cord by way of laminar and dural defect; density number of lesion consistent with fat;
(D) operative finding of lipoma infiltrating spinal cord through defect in lumbar dura mater (arrow).
bands transversing the space between the spinal cord and
the dura must be determined (10). Based on the ana-
tomic studies of Barson (14) and Gryspeerdt (37), Fitz
and Harwood—Nash (38) suggested the following criteria
for diagnosing a tethered cord (Fig. 15): (1) a low posi-
tion of the conus medullaris (a conus tip below the L2—3
interspace in a child older than five years should be con-
sidered abnormal); (2) a filum terminale greater than 2
mm wide; and/or (3) a dorsal position of the filum ter-
minale. In addition, a widened sac and laterally emerg-
ing roots are often seen with the above radiographic find-
ings.
Intraspinal masses are easy to diagnose with myelogra-
phy, as they usually demonstrate the features of an intra-
dural filling defect. They can be associated directly with
the conus or a malformed filum. The pathologic anat-
omy of these lesions may frequently be determined by
the CT density numbers [Fig. 13(C)] or by the MR image
(Fig. 8). The intradural passage of a lipomyelomeningo—
cele also produces tethering and a rather characteristic
myelogram [Fig. 13(B)], although a lipoma may present
without a cystic component in association with a thick-
ened filum terminale (Fig. 8). The CT or MR scan often
provides evidence of the involvement of the lipoma with
the spinal cord and roots, as well as of the presence of a
cystic cavity within the lipoma. The CT density numbers
are characteristically those of fat.
The most difficult and varied lesion to diagnose is
diastematomyelia, either with or without a median sep-
tum. As mentioned earlier, the vertebral anomalies often
indicate the approximate location of the bony, cartilagi-
nous, or fibrous septum, which produces a deﬁnite split
in the contrast shadow [Fig. 14(A)]. The cord halves are
rarely symmetrical, and the conus is found at an abnor-
mally low level (18). There can also be a fibrous or ab-
normal spinal root tethering the cord at or remote to the
site of the split cord (39). In some cases, there is no sep-
tum and these bands, not a spur, provide the posterior
fixation of the cord (39). The myelographic features of
diastematomyelia are well known (19). Generally the le-
sions are located in the thoracic region. If a median sep-
tum is demonstrated, it is often found at the lower mar-
FIG. 14. (A,B) Median septum (arrow) and split halves of spinal cord in diastematomyelia seen in air
myelogram and CT scan; (C) operative finding of split cord (lower arrow) and remnant of bony median
septum (upper arrow).

A B
FIG. 15. (A) Myelographic findings in spinal cord tethered by
thickened filum terminale and lipoma (lower arrow); conus
(upper arrow) located approximately at lower end of L3;
(B) operative finding of thick (>3 mm) filum terminale.
gin of the split halves of the cord (Fig. 14). A widened
spinal canal and vertebral anomalies, such as defects in
the posterior arch and interlaminar fusion, often mark
the site of the bony, cartilaginous or fibrous septum. A
CT scan at the site of the septum may demonstrate the
tissue characteristics of the septum, not only by the CT
appearance but also by the density numbers recorded
[Fig. l4(B)]. MRI is especially useful for preoperatively
evaluating the extent of the cord separation, as well as
the location and type of the diastomatomyelic peg (Fig.
9). Demonstration of this is important in planning the
proper operative strategy.
A frequently um'ecognized form of spinal cord tether-
ing is that associated with a repaired myelomeningocele
(21). Myelography with polytomography will demon-
strate, in these cases, a thinned or absent dorsal (to the
cord) subaraclmoid space cephalad to the tethered cord,
and an obtuse course of exiting nerve roots. Addition-
ally, the vertebral anomalies commonly associated with
myelomeningoceles are usually present in these cases.
MRI also demonstrates the tethering ofthe spinal cord at
the site of surgical repair and appears to be the procedure
of choice for evaluating delayed neurological deteriora-
tion in this condition (Fig. 10) (40).
Urologic Evaluation
In most cases, the early treatment of open dysraphic
defects is not preceded by an extensive urologic work—up,
NEURAL TUBE DEFECTS / 409
since a more precise diagnosis is possible only after the
age of two or three years. It is, however, often appro-
priate to perform intravenous pyelography to iule out
malformations of the genitourinary tract. It is important
to appreciate that over half of the children with myelo-
dysplasia have neurological deterioration of urological
function, although some will have evidence of re— or
neoinnervation of the external sphincter and the blad-
der. Most of these changes occur within the first three
years of life (41). In the occult spinal dysraphic condi-
tions, the evaluation of the genitourinary system is most
important in terms of diagnosis and of intra— and postop-
erative evaluation of surgical therapy. In addition, an
understanding of the pathophysiology allows the ratio-
nal approach to therapy during the postoperative phase
of treatment. At a minimum, this evaluation should in-
clude a urinalysis, blood urea nitrogen, and excretory
urogram. Even in asymptomatic cases, a full urodyna—
mic diagnostic study is necessary when there is evidence
of significant cutaneous or skeletal abnormalities. The
measurement of bladder function (cystometiy) is often
combined with external urinary and anal sphincter elec-
tromyography (EMG). When indicated, cystouretl1ro—
scopy and voiding cystourethrography complete the uro-
logic work—up.
Cystometiy is performed via an indwelling (transur—
ethral) catheter by infusing either a liquid or carbon
dioxide gas. The gas is more convenient to use and al-
lows rapid filling of the bladder. With either method the
patient is in a supine position, and the bladder is filled at
a constant rate (i.e., 100 ml/ min) while the bladder pres-
sure is continually monitored and recorded. A determi-
nation is made of the volume at which the patient per-
ceives bladder fullness, urge to void, and imminent
urination. It should be appreciated that the measured
bladder pressure includes change in intra—abdominal
pressure (IAP) as well, and therefore a pressure trans-
ducer attached to the anal EMG plug will measure IAP
changes so that the intravesicular pressure may be
coirected. The typical pressure—infusion curve is nonlin-
ear, with the early part of the curve characterized by a
relatively greater rise in vesicular pressure per unit vol-
ume of infusion than during the remaining portion of
the infusion phase. Usually a definite volume marks the
ﬁrst sensation of ﬁlling (around 120 1nl, but variable)
and the urge to void that precedes voluntary contraction.
This portion of the curve becomes more vertical.
An electromyogram (EMG) of sphincter activity is
valuable, since it relates sphincter activity to bladder fill-
ing and records the response to attempts to stimulate or
inhibit voluntary efforts to void. In addition, the electri-
cal pattern (such as polyphasic potentials) can often indi-
cate lower motor neuron disease. Recording of poten-
tials from an anal plug can also be useful, as there can be
considerable disparity between anal and urinary
sphincter involvement in neurologic disease. In general,

410 / CHAPTER 19
the results of the urodynamic studies depend on the cord
segment or root level involved. In the occult dysraphic
patient, a complete lower motor neuron lesion results in
an areﬂexic bladder and a denervated urinary or anal
sphincter. When the lesion is located above the sacral
area, an upper motor neuron lesion is usually found and
is characterized by a hyperreﬂexic bladder with or with-
out external sphincter dyssynergy. Cystoscopy and radio-
graphic studies will sometimes demonstrate in these
cases bladder trabeculations and, in severe obstructive
cases, ureteral reﬂux.
Miscellaneous
In some instances, full evaluation of cardiopulmonary
function is indicated, especially with the multisystem in-
volvement often seen in the myelomeningocele patient.
In cases of suspected hydrocephalus, CT scanning of the
head without enhancement or MRI is required to estab-
lish this diagnosis and other abnormalities ofthe nervous
system. It has been suggested that, in those patients with
significant anomalies in other organ systems, palm and
fingerprints as well as chromosomal studies be done to
establish the diagnosis of chromosomal errors or ﬁeld
defects (4).
Recently it has been shown that spinal— and scalp—re—
corded somatosensory evoked potentials (SEPs) are use-
ful in evaluating young adults and children with sus-
pected tethered spinal cord syndromes. Posterior tibial
SEPs are highly predictive of level and laterality of the
lesion. There is also a high correlation between the sever-
ity and extent of the lesion and extent of the abnormality
of the SEP (42).
INDICATIONS FOR SURGERY
There have been wide differences of opinion as to the
use of early surgical intervention in infants born with
open neural tube defects (26,43,44). There are many
moral, social, and medical issues that have been used to
restrict the early repair of myelomeningoceles and other
conditions associated with these neural defects, although
some programs have delivered maximum therapy with-
out selection (43). This selection process, however, has
changed during the past two decades largely because of
the improved results associated with progress in medical
and surgical therapy. The selection of care became a
moot issue in April 1985 under provisions of the Child
Abuse and Neglect and Prevention and Treatment pro-
grams. These rules require that all infants be treated with
all medical and surgical modalities unless (1) the infant is
chronically and irreversibly comatose, (2) treatment will
only prolong dying, and (3) treatment would not alter
the survival of the infant after utilizing an inhumane
treatment (44).
The approach to treatment of the myelomeningocele
has especially changed over the past 25 years, because
prior to adequate control of hydrocephalus the treat-
ment of an open spinal defect was primarily academic
(45). The closure of these defects within 48 hours after
birth was proposed in 1963, in order to prevent infection
and diminish the degree of lower limb paralysis. A re-
duced incidence of central nervous system infection re-
sulted from this policy, although the proposed beneﬁcial
effect on limb function has not occurred (45,46). In gen-
eral, the goals and timing oftreatment are based on medi-
cal factors, although social factors are also considered in
the individual case (1,3). The question of the advantages
of immediate (<24 hours), early (two to seven days), or
late surgical repair is still unsettled, but most evidence
supports the view that the incidence of infection and
retained neurological function are not significantly dif-
ferent between the immediate and early repair groups
(46,47). It should be appreciated that treatment of the
myelodysplastic child is invariably a long—term commit-
ment by the medical team and family.
There is little controversy concerning the indications
for operative intervention in the occult group of spinal
malformations, although the timing of such procedures
has not been clearly established. The notion that prophy-
lactic surgery prior to a period of rapid truncal growth
seems reasonable based on our understanding of the role
of traction in the development of neurological dysfunc-
tion. There is little question, however, that the onset of
orthopedic and urologic syndromes with defined myelo-
graphic abnormalities requires timely surgical interven-
tion (48). Most experienced clinicians recommend surgi-
cal relief from traction or compressive lesions that are
capable of adversely affecting spinal cord function. The
final decision to operate, as well as the selection of the
appropriate operative procedure, is based on the radio-
graphic localization and description of the spinal lesion.
OPERATIVE MANAGEMENT
Position
The myelomeningocele patient is generally placed in a
prone position unless a ventricular shunt is to be inserted
at the same time. In that case, the hips are slightly rotated
to expose the ﬂank for the insertion of the abdominal
catheter. In all cases, pressure on the abdomen is mini-
mized by using chest rolls or, in the older patient, an
orthopedic frame. Ideally the abdomen should be freely
suspended. However, contact with the heating pad used
with infants is often lost. It is, therefore, usually neces-
sary to heat the operating room to between 80 and 85°F
in order to control the child's core temperature. External
heating lamps are used primarily during induction, and
temperature loss prevented by the use of a plastic wrap

around the exposed skin outside of the operative field.
The legs of older patients are wrapped with elastic ban-
dages all the way to the groin. In recent years we have
been routinely monitoring SEPs and the electromyo—
graphic activity of the anal sphincter during the opera-
tive procedure. The electrodes are placed following the
final positioning of the patient.
Anesthesia
In newborn infants, the repair of a small myelomenin—
gocele may be carried out under local anesthesia. In most
other cases we generally use endotracheal anesthesia
with a nondepolarizing muscle relaxant (e.g., atracurium
besylate). Recovery from neuromuscular blockade can
be easily and rapidly accomplished with an anticholines—
terase reversing agent prior to stimulating roots for anal
sphincter activity.
Operative Observations
In general, all of these cases are done using magnifica-
tion. Operating telescopes with a power of between 2.5
and 3.5 provide adequate magnification. The ﬁber—optic
light source has also proven to be a necessity in most of
these cases. The skin incision in the myelomeningocele
patient circumscribes the external lesion, saving as much
normal skin as possible. For large defects, consultation
with plastic surgery allows proper planning for the shape
of the incision, preparation of donor sites, and position-
ing of the patient. The closure of the defect should be
carried out in four layers, as shown in Figure 16 (49).
Great care is taken to preserve functional neural ele-
ments by using stimulation prior to dissection of these
structures, generally accomplished by observing the
movement in the extremities, as well as sphincter and
bladder contraction as visualized on the dual channel
recorder. After separating the neural plaque [Fig. l6(A)]
from the adjacent epithelial strip, the plaque is covered
with the pia—araclmoid (layer one). The remnant of the
dura and/or paraspinal fascia provides the next level of
closure (layer two). It has been suggested that the circula-
NEURAL TUBE DEFECTS 4 1 1
tion of cerebrospinal ﬂuid around the neural placode can
be enhanced by utilizing a dural graft. This enlargement
of the dural sac may prevent tethering of the repaired
myelomeningocele (50). Finally the skin is approxi-
mated with subcutaneous sutures (layer three) and fine
skin sutures (layer four). Intravenous ﬂuorescein may be
used to demonstrate adequate circulation of the skin su-
ture line. If it is inadequate, relaxation incisions, skin
grafting, and rotational ﬂaps may be necessary to ensure
that a tight closure is achieved without tension at the
suture line. In some cases, the extent ofthe spina biﬁda is
great, and there is difficulty in producing a strong cover-
ing layer for the reconstructed cord and meninges. This
problem can be solved by using a large latissimus dorsi
muscle ﬂap or by the medial rotation of the spread pedi-
cles (with their muscle mass) by surgical fracture (51,52).
The site of the skin incision in the occult dysraphic
patient is dictated by the myelogram. In the case of a
dermal dimple or sinus, a midline elliptical incision is
used in order to follow and remove these structures; the
shape ofthe incision for a lumbosacral lipoma is dictated
by the geography of the lesion itself. In the case of simple
tethering by a thickened filum terminale, fibrous intra-
dural bands, or aberrant roots, the sectioning of these
structures should occur only after stimulation studies.
Lipomas that enter the dural defect and inﬁltrate the
spinal cord or cauda equina must be dissected carefully.
In most instances, it is safe to perform only a subtotal
removal. A careful, watertight closure of the dura with or
without a fascial graft should follow the subtotal resec-
tion. A multilayer closure, after removal of most of a
subcutaneous lipoma, will lead to a satisfactory cosmetic
result. The strategy for dealing with diastematomyelia
depends on the demonstration of a median septum. The
median septum, regardless of its composition, should be
removed. The dural sleeve that is present in one—half of
the cases should also be removed. In addition, tethering
bands at the site of the septum or at the conus or filum
should be sectioned. Great care must be taken while re-
moving the septum in order not to damage the adjacent
cord. A large collection of vessels that may cause nui-
sance bleeding is often encountered at the base of the
septum. If anticipated, this bleeding is usually easy to
control under magnification.
FIG. 16. (A) The neural plaque has been sepa-
rated from the skin margin. The straight arrow
indicates the direction the neural plaque will
go after its inversion into the open spinal canal
following the closure of the lateral margins
(curved arrows) of the pia—arachnoid mem-
brane. (B) Following closure of the pia—arach-
noid membrane, the lateral margins of the re-
maining dura and/or fascia are closed overthe
neural tissue, thus producing a complete
membranous tube. (Modified from reference
49.)

412 / CHAPTER 19
The intraspinal compressive lesions are removed in a
manner similar to that used for intradural tumors. Great
care is taken to preserve the adjacent or involved neural
tissue. In addition, intradural tethering bands sometimes
seen with these lesions must be found and severed. The
extradural fixation bands are technically easy to remove
prior to a multilayered closure.
COMPLICATIONS AND POSTOPERATIVE CARE
The major complications following myelomeningo-
cele repair are poor skin healing, infection, and spinal
ﬂuid leak. Secondary wound repair generally solves these
problems, although the presence of severe hydrocepha-
lus may require ventricular shunting prior to secondary
closure. The problem of spinal ﬂuid leak and stress on
the site of myelomeningocele repair in children with hy-
drocephalus at birth might be alleviated by inserting a
ventricular shunt at the time of the back repair (53). Al-
ternatively, placement of an infant ventricular reservoir
and postoperative tapping can accomplish the same go al
in those infants with grossly contaminated wounds. Post-
operatively, the anal opening is shielded from the repair
site by a plastic drape attached to the skin of the but-
tocks. An abdominal sling or gauze donut can be used to
hold the infant in a prone position. Bladder emptying is
carried out at intervals by a crede maneuver. Oral feed-
ings are started as early as possible, generally within 12
hours of surgical repair. Daily head measurements are
most important, and any change in the rate of growth
and fullness of the open anterior fontanelle indicates the
development of hydrocephalus and the need for a confir-
matory CT study.
The most devastating complication in the surgical re-
pair of an occult spinal malformation is increasing the
neurologic deficit. This occurs in only a small percentage
of cases and is more often associated with lipomyelo—
meningoceles than simple tethering bands. The use of
lower extremity and sphincter monitoring should de-
crease this complication. Infection and wound dehis—
cence are relatively infrequent complications, as most of
these patients are in good health with a proper nutri-
tional status. Spinal ﬂuid leaks are also uncommon and
are more often associated with those cases with a congeni-
tal dural defect (such as a lipomyelomeningocele). The
development of a spinal ﬂuid leak following repair of
these defects is more common when the dural patch is
composed of artificial or dehydrated material. Fascial
autografts may prevent this complication.
Early ambulation and institution of intensive bladder
care and physical therapy are initial goals in most of the
surgically treated occult lesions. The postoperative care
of the bladder depends on the level of the neurologic
lesion. Initially, in the newborn, simple crede ofthe blad-
der provides adequate emptying. In the older child and
in many of the occult spinal dysraphic patients with
bladder involvement, continence can be achieved by in-
termittent catheterization. In some cases, pharmacologic
agents have been used alone or in combination with a
program of intermittent catheterization. In many of
these cases there is a urinary storage problem owing to
vesical hyperreﬂexia. Oxybutynin has proven useful in
this situation by producing muscle relaxation. If there is
an associated spasm of the external sphincter, polysyn—
aptic inhibitors, such as baclofen or diazepam, can be
used. The choice of pharmacologic agent depends on an
understanding of the pathophysiology as determined
from the urodynamic studies. The primary goal of a ther-
apeutic program for bowel training is to achieve con-
trolled spontaneous defecation by taking advantage of
the gastrocolic reﬂex, and by adjusting the diet to include
natural laxatives and high fiber content. Combined with
this approach is the judicious use of suppositories, ene-
mas, and oral purgatives (4). The use ofelectrical stimula-
tion to achieve bowel or bladder continence is still in the
early phases of development and has no role in the early
postoperative treatment of sphincter disorders of the
bowel or bladder.
RESULTS
It is difficult to quote accurate figures for results in
myelomeningocele patients because of the complexity
and variability of the syndromes associated with these
myelodysplastic conditions. In those patients treated ag-
gressively for both the dysraphic problem and hydroceph-
alus, the rate of survival is now in the range of 90 percent
or better. The quality of survival is very difficult to evalu-
ate. It can be shown that the final outcome is related to
early and aggressive treatment, level of the neural lesion,
state of the hydrocephalus, and presence or absence of
infection. For example, in one study 64 percent of pa-
tients with a midlumbar lesion had normal to high intel-
ligence: this was true of only 38 percent with lesions in
the thoracic area (3). It should be understood that even
with a normal intelligence quotient (IQ), the myelodys-
plastic survivor has moderate to severe visual—motor per-
ceptual defects (1). Ames and Schut have reported that
following surgical therapy of 79 children with myelome-
ningocele and hydrocephalus, 71 percent were ambula-
tory, with most using crutches (54). In this group, 48
percent were considered competitive, with IQs of 80 or
better. This figure was 90 percent in the 36 dysraphic
children who were not hydrocephalic. Similar results
have been presented by ShurtlefT in a much larger group
of patients (3). In this study, almost 94 percent of the
dysraphic children with significant or well—controlled hy-
drocephalus had IQs of 80 to 110 or more. The IQ level
was much lower, however, in the patients who were
shunt dependent or who had a history of infection or

hemorrhage into the cerebrospinal fluid (3,53). Satisfac-
tory socioeconomic adjustment and educational achieve-
ment were also related to IQ and level of the lesion. Over
70 percent of the patients with a normal IQ achieved a
happy adjustment, with 63 percent becoming indepen-
dentin all activities. In the patients whose lesions were at
the high lumbar and thoracic level, only 50 percent were
happy, whereas 75 percent of the patients with sacral
lesions were described as happy.
The results in the surgical treatment of occult spinal
dysraphism are a little easier to quantify. James and
Lassman have reported that, in a variety of occult dysra-
phic cases followed from 1 to 13 years after surgical treat-
ment, 17 percent remained normal, 43 percent were ei-
ther questionably unchanged or improved, 38 percent
were unchanged, and 2 percent were worse (11). In a
later study, James and Lassman reported that in seven
uncomplicated cases of diastematomyelia, all remained
normal after surgery, whereas in three patients with dia-
stematomyelia and incontinence, only one remained
unimproved (56). In those patients with diastematomye-
lia and a history of progressive neuropathy, 24 percent
were worse following operative removal of the median
septum, while 35 percent remained the same and 41 per-
cent improved. In reviewing the world experience for
this condition, Kennedy reported that a corrective opera-
tive procedure for diastematomyelia resulted in improve-
ment in 75 percent of the cases, while in 15 percent the
patients were not improved (57). In this same review,
there was a worsening of the neurologic status in 6 per-
cent of the cases. In a large series of treated intraspinal
lipomas, Bruce and Schut reported that in 27 of their
cases with normal preoperative examination, some 89
percent remained normal after surgery (23). In the 23
cases with preoperative neurologic deficits, some 35 per-
cent improved, whereas 56 percent were unchanged and
9 percent had an increase in their deficit. The high inci-
dence of urinary complications seen at the time of diag-
nosis in patients with a lipomyelomeningocele is unfortu-
nate, since surgical treatment seems not to reverse these
deficits in many cases (24). U should be appreciated that
success is measured not only by improvement in the neu-
rologic deficits but also by prevention of further neuro-
logic deterioration. On this basis, the expected success of
surgical intervention in occult spinal dysraphism is in
excess of 90 percent.
OUTCOME
The progress that will occur in dealing with severe
myelodysplasia will be in the ﬁeld of genetic counseling
and the antenatal screening for a—fetoprotein. The com-
mitment of our society for the required orthopedic, uro-
logic, and neurosurgical care of the myelomeningocele
patient is great and continues during the lifespan of the
NEURAL TUBE DEFECTS / 413
individual. It has been shown that actively treating the
myelodysplastic child can result in great satisfaction for
all those involved in the care of these children, as in-
creasing numbers of the survivors fill important roles in
the family unit and useful places in society (1,43).
The children with closed lesions of the spine are gener-
ally of normal intelligence and easily enter the main-
stream of society. There is, however, a continued role for
orthopedics in reconstructing abnormalities of the limbs
and spine in some of these cases. Urologic evaluation
continues to be most important, although most of these
children can obtain satisfactory results with use of inter-
mittent catheterization, biofeedback therapy, and phar-
macologic treatment of the vesicosphincter abnormali-
ties. There is little question that the comprehensive
diagnostic and therapeutic approach advocated will ulti-
mately result in early operative intervention in order to
preserve normal function rather than attempts, some-
times in vain, to restore lost function (33).
REFERENCES
1. McLaughlin JF, Shurtleff DB. Management of the newborn with
myelodysplasia. Clin Pediatr (Phila) 1979:18:463-476.
2. Vogter DM, Kaufman HH. Spinal dysraphism—a review. W V
Med] 1985:81:142-145.
3. Shurtleff DB. Myelodysplasia: Management and treatment. Curr
Probl Pediatr 1980; 10:1 -98.
4. Fishman MA. Recent clinical advances in the treatment ofdysra-
phic states. Pediatr Clin North Am 1976;23:517-526.
5. Brock DGH, Barren L, Van Heynington V. Prenatal diagnosis of
neural-tube defects with a monoclonal antibody specific for acetyl-
cholinesterase. Lancet 1985; 1:5-8.
6. Goldberg MF, Oakley, GP Jr. Interpreting elevated amniotic fluid
alpha fetoprotein levels in clinical practice: use of the predictive
value positive concept. Am J Obstet Gynecol 1979:133:126-132.
7. Friede RL. Developmental neuropathology. New York: Springer-
Verlag, 1975.
. Lemire RJ. Neural tube defects. JAMA 1988;259:558-562.
. Lemire RJ, Loeser JE, Leech RW, et al. Normal and abnormal
development of the human nervous system. Hagerstown, MD:
Harper and Row, 1975.
10. Gardner WJ. Myelocele: Rupture of the neural tube? Clin Neuro-
surg l967:l5:57—79.
11. James CCM, Lassman LP. Spinal dysraphism. New York: Apple-
ton-Century-Crofts, 1972.
12. Gilbert JN, Jones KL, Rorke LB, ChernofTGF, James HE. Central
nervous system anomalies associated with meningomyelocele. hy-
drocephalus, and the Arnold-Chiari malformation—Reappraisal
of theories regarding the pathogenesis of posterior neural tube de-
fects. Neurosurgery 1986;18:559-564.
13. Laurence KM, Tew BJ. Natural history of spina bifida cystica and
cranium bifidum cysticum. Arch Dis Child 1971:46:127-138.
14. Barson AJ. The vertebral level of termination of the spinal cord
during normal and abnormal development. JAnal 1970;106:489-
497.
15. Wilson DA, Prince JR. MR imaging determination ofthe location
of the normal conus medullaris throughout childhood. AJNR
1989;10:259-262.
16. Bentley FJR, Smith JR. Developmental posterior enteric remnant
and spinal malformations. Arch Dis Child 1960;5:76-86.
17. Talwaker VC, Dastur DK. "Meningoceles" and "myelomeningo-
celes” (ectopic spinal cord). J Neural Neurosurg Psychiatry
1970:33:251-262.
18. Herren RY, Edwards JE. Diplomyelia (duplication of the spinal
cord). Arch Pathol 1940:30:1203-1214.
\OOO

CHAPTER 20
Disc Disease
Clark Watts and Howard Smith
HistoricalAspects, 415
Anatomy, 415
Path0l0gy,416
Lumbar Disc Disease, 416
General Considerations, 416
Symptoms, 4 17
Signs, 4 1 8
Localization, 418
Initial Management, 419
Diagnostic Studies, 419
Surgery, 42 1
Chemonucleolysis, 424
Percutaneous Nuclectomy, 424
Reoperation, 424
Unusual Hemiations, 425
Cervical Disc Disease, 425
Any discussion of disc disease must begin with a defini-
tion of the scope of such disease. To so1ne, disc disease is
defined narrowly as a disorder resulting fro1n rupture of
the intervertebral disc. Others include primary disc de-
generation and the spondylosis that results fro1n it. Still
others include disorders of the discs associated with se-
vere spinal trauma including fracture, as well as aseptic,
septic, and granulomatous discitis. Most of this chapter
will be devoted to the understanding and management
of ruptured intervertebral disc disease. So1ne of the dis-
cussion will be devoted to bacterial infections of the disc,
primarily as a complication of surgery. Disc disease asso-
ciated with primary spinal trauma is discussed in
Chapter 22, and spondylosis in Chapter 21.
HISTORICAL ASPECTS
While the brilliant work of Schmorl, published in the
German literature in the 1920s, is the cornerstone of our
C. Watts and H. Smith: Division ofNeurosurge1y, Univer-
sity of Missouri School of Medicine, Columbia, Missouri
65212.
Princi les 0fNeur0surgery,
edite by RobertG. Grossman. Rosenber © 1991.
Published by Raven Press, Ltd., New Yor .
General Considerations, 425
Symptoms, 425
Differential Diagnosis, 426
Localization, 426
Diagnostic Studies, 427
Management, 427
Surgery,427
Thoracic Disc Disease, 431
General Considerations, 431
Presentation, 431
Diagnosis, 431
Surgery, 43 1
Discitis, 432
Vertebral Osteomyelitis, 432
Postoperative Discitis, 433
Discitis in Children, 434
References, 434
current understanding of disorders of the intervertebral
discs, it took the detailed embryologic, anatomic, and
pathologic correlations of Keyes and Compere to pro-
vide the basis for our clinical application of this work (1).
This was accomplished in 1934 with Mixter and Barr's
published observations on radicular compression by her-
niated disc material as a co1n1non cause of sciatic pain
(2). In reaching their conclusions, Mixter and Barr made
use of the observations of many other investigators, in-
cluding Elsberg who reported 15 cases of chondroma of
the spinal canal in 1913, pointing out the similarity be-
tween the chondromata and the substance of the inter-
vertebral disc (3). Also of historical importance is Stoo-
key's paper in which he clearly described a cervical disc
rupture, although he misunderstood the precise patholog-
ical nature of the lesion (4).
ANATOMY
An intervertebral disc resides between the bodies of
each of the vertebrae below C2 and above SI. The discs
serve to absorb the shock of stress applied to the spine, as

416 / CHAPTER 20
well as to permit some degree of spinal motion, particu-
larly flexion and rotation (5). Each disc is composed of
three components: the nucleus pulposus, the annulus fi-
brosus, and the cartilagenous endplates (1).
The center of the disc is occupied by the nucleus pul-
posus, which consists of a protein gel containing rnuco—
polysaccharides (6). The annulus is composed of con-
centric larninated bands of fibrous tissue and forms the
outer border of the disc. Medially, the annular fibers are
attached to the cartilaginous endplates of the disc,
whereas laterally these fibers are attached directly to the
vertebral body by Sharpey's fibers. Anteriorly, the fibers
of the annulus merge with the anterior longitudinal liga-
ment, which imparts additional strength to the disc. Pos-
teriorly, a similar attachment with the posterior longitu-
dinal ligarnent is noted. The posterior longitudinal
ligament is narrower than the anterior longitudinal liga-
ment, although there is a rhomboid—shaped widening of
the posterior longitudinal ligament at the disc space. The
posterolateral aspect of the disc is unsupported by liga-
ment. This relative lack of support undoubtedly ac-
counts for the preponderance of disc ruptures, especially
in the lumbar area, occurring through the posterolateral
annulus.
The endplates of the discs, composed of hyaline carti-
lage, are cemented to the intervertebral surfaces of the
superior and inferior vertebral bodies by a thin layer of
calcified cartilage, which in some places permits the
bone marrow to reach the surfaces of the endplates. Each
cartilaginous endplate extends to the posterior margin of
the superior and inferior vertebral bodies. In the anterior
and lateral regions, however, the endplate ends abruptly,
abutting against the outer raised rim of the vertebral
body, the epiphyseal ring.
The intervertebral disc is relatively vascular in chil-
dren and young adults (7), and small aiteries and veins
are even found in the region of the cartilaginous end-
plates. By the third decade, however, the arteries and
most of the veins disappear, and thenceforth nutrients
are supplied to the intervertebral disc by diffusion from
the marrow cavity through the endplates.
The nerves of the intervertebral disc are primarily un-
rnyelinated and present a type of terminal arborization
characteristic of pain fibers (8). They exit the spinal
nerve distal to the dorsal root ganglion by way of the
posterior primary division of the root and return through
the intervertebral foramen, entering the vertebral canal
as the recurrent sinuvertebral nerve (9). This nerve sup-
plies branches to the posterior longitudinal ligament,
periosteum, epidural blood vessels, dura mater, facet
joint, and superficial layers of the annulus fibrosus (8).
Each branch to the intervertebral disc probably supplies
the level of its entrance into the vertebral canal and one
segment below this level (9). It is this nervous network
that may be the source of back and leg pain not asso-
ciated with true disc herniation. In patients undergoing
larninectoiny under local anesthesia for disc rupture,
Murphey has shown that stimulation of the posterior
longitudinal ligament and medial annulus will produce
back pain, whereas stimulation of the more lateral annu-
lus and the facet joint results in both back pain and leg
pain referred to the general region of the dermatome of
the appropriate spinal root (10).
PATHOLOGY
The primary pathology of the intervertebral disc is
produced by aging (11,12). With aging, there is frag1nen—
tation of the posterior annulus, along with a loosening of
its attachment to the longitudinal ligaments. This is ac-
companied by thinning and fissuring ofthe cartilaginous
endplates, with invasion of granulation tissue from the
adjacent bone. By the eighth decade, the laminar struc-
ture of the annulus is lost. Nuclear degeneration in all
cellular elements of the disc is obvious. Additionally, the
water content of the nucleus pulposus decreases from 88
percent at birth to 70 percent in the eighth decade (12),
and, primarily by 20 years of age, the water content of
the annulus decreases from 78 to 70 percent. In the nu-
cleus pulposus, there develops an increased ratio of kera-
tosulfate to chondroitin sulfate; as mucopolysaccharide
is broken down, it is replaced by collagen. These changes
result in a decreased disc volume. There is also a progres-
sive decrease in elasticity, leading to increased stiffness
and residual deformation, with a decreased capacity for
recovery from compression of the disc, and poor energy
dissipation (a decreased internal—dampening capacity)
by the disc. This leads to an increased vulnerability to
disc rupture until the sixth decade. Disc rupture after the
sixth decade is unusual, but increasing vertebral spondy—
losis or osteophyte formation is noted. These bony
changes are especially prominent in the posterior and
posterolateral regions of the vertebral bodies and discs,
leading to the radicular and myelopathic syndromes of
spondylosis.
LUMBAR DISC DISEASE
General Considerations
While there is disagreement in the literature about the
exact incidence and prevalence of intervertebral disc dis-
ease, there is general agreement on certain demographic
features ofthis condition. Disorders ofthe spine are prob-
ably the rnost common cause of disability in the working
population, with most complaints referred to the lumbar
area. In some series, lumbar disc disorders outnumber
cervical disc disorders by ten to one, with thoracic disc
disorders being rare (although clinically very important
in terms of the disability they can produce). With regard
to intervertebral disc rupture, males outnumber females

by three to one. The greatest incidence of disc rupture
occurs in the fifth decade, with the more acute syn-
dromes appearing earlier and the more chronic ones ap-
pearing later. The average neurosurgeon will spend ap-
proximately 18 percent of his or her time in the
outpatient treatment of intervertebral disc disease (ap-
proximately 20 percent of case load). The inpatient
treatment data are similar, with the time spent on disc
disease being 16 percent and the frequency of cases being
approximately 17 percent (13).
Approximately 90 percent of adult lumbar disc rup-
tures occur at the two most caudal discs (L4—L5 and L5-
Sl), with each contributing half of this total (14,15).
Most of the remaining ruptures occur at L3—L4, with
ruptures ofthe upper lumbar discs (T12—L1, L1—L2, and
L2—L3) being quite rare (16).
Although unusual, intervertebral disc rupture does oc-
cur in adolescents (17). In most instances, it is associated
with a documented traumatic episode. The presentation
is similar to that in the adult. Small numbers of cases
involving preadolescent children and due to speciﬁc trau-
matic episodes are recorded in the literature, with a 9-
year—old child representing the youngest case (18). Unfor-
tunately, the lack of awareness among physicians of the
possibility of intervertebral disc rupture in children re-
sults in a more protracted period of observation and eval-
uation in such cases. Most are given the diagnosis of
either a psychological disorder or, ultimately, a spinal
tumor. However, a careful examination of the ﬁndings
in these cases indicates that they present with histories
similar to those of older children and adults.
Symptoms
The patient with lumbar intervertebral disc disease
will present with either of two basic symptom corn-
plexes. The rnost easily recognized occurs in the person
with a job that requires significant bending and lifting
throughout the day. The affected individual usually has a
history of occasional nagging backache, which is relieved
by a temporary reduction in physical activity. The acute
symptom complex begins with the sudden onset of dis-
comfort in the lower back. This may range from a pull-
ing or tearing sensation to excruciating localized pain.
There may be paresthesias into the leg, which may or
may not be localized to a dermatome of a lumbar spinal
root. With decreased physical activity, the pain contin-
ues but is reduced in intensity. Within a few hours the
paresthesias, which may have persisted or disappeared
shortly after the onset of pain, are replaced by pain ra-
diating into the leg in an appropriate dermatomal distri-
bution. As in the case of disc—related back pain, this ra-
dicular pain is usually eased by reduced physical activity.
For several days following the onset of symptoms, the
patient will note that increased activity exacerbates both
Disc DISEASE / 417
back and leg pain. The pain also increases with straining,
such as in coughing, bowel evacuation, and lifting.
The foregoing are the typical symptoms of a herniated
lumbar intervertebral disc. More careful evaluation of
these symptoms will reveal details that may be of addi-
tional value in localizing the site of the rupture. Back
pain associated with vague, aching, deep leg pain, and
approximating in distribution a known dermatome, sug-
gests an annular rupture with the herniation of fibrotic
nuclear material into the annulus and the stimulation of
pain ﬁbers within the annulus. With bed rest, the leg pain
usually disappears and the back pain decreases because
of decreased pressure within the disc and partial internal
decompression of the nuclear fragment brought about
by the recumbent position. The presence ofback and leg
pain in a speciﬁc dermatomal pattern that is reduced in
intensity by the recumbent position suggests a disc her-
niation with compression and distortion of the spinal
root, but without foraminal entrapment of the root.
There may or may not be weakness in the motor distri-
bution of the spinal root. The persistence of severe leg
pain beginning hours after the onset of back pain and
despite bed rest suggests the impaction of a herniated
disc fragment into the foramen. This is usually asso-
ciated with numbness and weakness in the distribution
of the spinal root.
Minor bladder dysfunction in cases of disc injury,
such as hesitancy in voiding, is usually due simply to
back pain produced by straining. The same can be true
of sexual dysfunction, especially in male patients. If, how-
ever, there are significant urinary system symptoms,
such as retention, or the inability to develop penile erec-
tion in a nrale patient, and especially if these are asso-
ciated with profound back pain, a large midline hernia-
tion with cauda equina compression should be
suspected. In such instances, sensory and motor corn-
plaints usually reﬂect the involvement of multiple roots,
often bilaterally. This point should be kept in mind when
one is presented with a patient who experiences sudden
bilateral sciatic and femoral pain, paraparesis, and uri-
nary retention.
The rnore common symptom complex of lumbar in—1
tervertebral disc disease is a chronic pain syndrome. The
patient notes intermittent back pain for months or years,
requiring periods of decreased physical activity for sev-
eral days and often resulting in loss of work time. With
the passage of time, the initial back pain gradually be-
comes associated with leg pain preceded by a period of
intermittent paresthesias. The leg pain and paresthesias
may have a dermatomal distribution but, more often,
are less well localized. Generally, pain, extremity weak-
ness, and urinary and sexual dysfunction are described
by the patient in less dramatic and discrete terms than in
the case of an acute herniation and are not unlike the
symptoms of spinal stenosis and spondylosis. The acute
symptoms of the chronic pain syndrome may be precipi-

418 / CHAPTER 20
tated by minor episodes of trauma, such as coughing,
taking an awkward step, or turning over in bed.
Signs
In seeking physical abnormalities in the patient with
lumbar intervertebral disc disease, the physician should
examine the undressed patient and begin by observing
the patient's posture and gait. In such cases, the normal
lumbar lordotic curve is ﬂattened, and the patient tends
to hst toward the side contralateral to the diseased disc,
with an elevation of the ipsilateral hip. It is as if the pa-
tient were attempting to open the foramen on the af-
fected side and accomplish a decompression of the root.
Paravertebral muscle spasms, more pronounced on the
affected side, may be palpated. However, this is an unre-
liable sign of disc disease, since any painful condition of
the spine or muscles may produce muscle spasms. Addi-
tionally, the disturbance of posture may make one group
of paravertebral muscles appear more prominent. Pain
will limit the motion of the lumbar spine in all directions
and is increased upon lateral bending to the affected side.
This is in contrast to unilateral myositis, in which .lateral
bending to the opposite side is restricted by the intense
muscle spasms on the affected side. Percussion over the
diseased intervertebral disc space will usually elicit a
complaint of localized back pain and may produce leg
symptoms. However, this also is a nonspecific sign, since
other painful disorders of the back, such as a simple
strain, may yield the complaint ofpain upon percussion.
If performed properly, the sciatic nerve stretch test can
be most helpful in diagnosing disc disease. As described
by Lasegue in 1864, the test first involves ﬂexion of the
hip at right angles to the trunk, followed by extension of
the knee with the patient in the recumbent position (19).
A positive result of the test consists of leg pain in the
distribution of the patient's spontaneous symptoms and
suggests rupture of the intervertebral disc with cornpres—
sion of a nerve root contributing to the sciatic nerve,
usually at L4 to S1. Elevation of the straightened leg by
itself may give a false—positive response, owing to the
stretching of irritated muscle groups in the proximal part
of the leg. Modifications of the Lasegue test may also be
useful in diagnosing disc disease and include sirnulta—
neous dorsiﬂexion of the foot as the knee is extended.
Another suitable variation of the test is to have the pa-
tient sit with the distal leg dangling over the edge of the
examining table. The leg is extended at the knee. If this is
done while the examiner is testing deep tendon reﬂexes
or sensory function in the distal leg, it may elicit a more
objective response from the patient, at least with regard
to the angle of the extension required to produce the first
complaint of pain. If the Lasegue test on the contralat-
eral leg results in ipsilateral complaints (the crossed-
straight—leg raising sign), the results are felt by some to be
even more confirmatory of disc disease. Internal and ex-
ternal rotation of the hip is performed to exclude hip
disease, which will yield Patrick's sign or the fabere sign.
Muscle strength in the affected leg may be tested in a
variety of ways. As noted above, the physician should
observe the patient's gait for patterns of weakness. The
patient's thigh strength may be observed by asking the
patient to step up onto a low stool repeatedly with the
affected leg. Dorsiﬂexion of the feet may be observed by
asking the patient to walk on his heels toward the exam-
iner. Plantar ﬂexion may be observed while the patient
walks on the toes and balls of the feet. An evaluation of
specific muscles should then be done. Quadriceps weak-
ness can be detected by having the patient resist ﬂexion
of the extended knee. The physician can apply force
against the dorsiﬂexed foot to test the tibialis anterior
muscle, against the great toe to test the extensor hallicus
longus, and against the plantar ﬂexed foot to test the
gastrocnemius and soleus muscles, comparing the
muscle strength in the affected leg with that in the unaf-
fected leg.
Sensory examination is accomplished by testing the
individual dermatomes for light touch and pin prick. Oc-
casionally, however, especially with pin prick, the pa-
tient will note hyperesthesia, often associated with hy-
perpathia, in the appropriate dermatome.
Reﬂex testing of the lower extremities in lumbar inter-
vertebral disc disease is less reliable than the tests dis-
cussed above. The reﬂexes may be exaggerated or sup-
pressed by pain and muscle spasms. Additionally, the
myotatic reﬂexes diminish in intensity with age. The ex-
aminer should cornpare the patient's reﬂexes bilaterally,
looking for asymmetry.
/
Localization
Before discussing the locahzation of disc disease, it
should be recalled that the lumbar spinal roots exit at the
foramen below the appropriate vertebra. For example,
the L1 root exits at the foramen between LI and L2, and
the L5 root exits at the foramen between L5 and SI. It
should also be recalled that the anterior border of each
foramen is formed by the most lateral extent of the disc
at each level, and that the root travels caudally and lat-
erally within the spinal, canal prior to entering the fora-
men. Thus, for example, the L4 root enters the epidural
space opposite the posterolateral aspect ofthe L3—L4 disc
and is associated with the L4—L5 disc only in its most
lateral extent, as the root enters the foramen. The typical
disc rupture occurs through the posterolateral annulus
and, therefore, tends to cause compression of the root
that exits at the foramen below. Thus, the typical L3—L4
disc rupture will affect the L4 root, an L4—L5 rupture will
affect the L5 root, and an L5—Sl rupture will affect the S1
root.
An L4 root syndrome will be characterized by back
and radicular pain along the medial aspect of the knee

and distal leg to the ankle. Hypesthesia will be noted in
this distribution. Weakness in the quadriceps will be
found, and a diminished quadriceps deep tendon reﬂex
will be noted. In an L5 syndrome, the pain and hypesthe—
sia will be on the dorsornedial aspect of the foot, invari-
ably in the dorsal web space between the first and second
toes. Weakness or atrophy of the muscles supplied by the
peroneal nerve will be observed, expressed as a weakness
of dorsiﬂexion of the great toe, or the foot, or both. An
absent or diminished posterior tibial deep tendon reﬂex
is inconsistently noted. The findings in an S1 syndrome
are paresthesias, pain, and hypesthesia on the lateral
aspect of the foot and sole including the heel; weakness
or atrophy of the gastrocnemius and soleus muscles,
demonstrated by a weakness of plantar ﬂexion; and a
diminished Achilles‘ deep tendon reﬂex.
Syndromes produced by ruptures of the first and sec-
ond lumbar intervertebral discs are not as clear as those
described above, for several reasons. One reason is that
the epidural space is less generous at these locations than
in the lower lumbar area; the cauda equina contains
more nerve roots, more closely packed together. There-
fore, even small ruptures can readily involve multiple
roots as they descend past the rupture site. Conse-
quently, a greater number of bilateral symptoms and
signs occur with Ll—L2 and L2—L3 disc ruptures. Also,
the ruptures tend to be more medially located. Thus,
back pain without radicular pain, or with referred pain,
is more common than with ruptures at lower levels. The
pain may radiate in a multidermatomal pattern into the
leg. Additionally, there is a greater propensity for more
severe motor and bladder symptoms, and both the quad-
riceps and the Achilles‘ deep tendon reﬂexes may be af-
fected. Finally, although true disc ruptures in this area
usually present with acute syndromes, the chronic pro-
gression of symptoms may make it difficult to distin-
guish between disc disease and neoplasm.
Initial Management
The overwhelming majority of patients with interver-
tebral disc disease, no matter how acute the presentation,
can be managed satisfactorily with an appropriate non-
surgical regimen. The patient should be put on bed rest
for several days and, since it is virtually impossible to
keep the patient totally on bed rest, advised to arise
brieﬂy only for the maintenance of personal cleanliness
or the relief of boredom. Generally the patient will re-
quire little beyond aspirin or 0.5 grain of codeine every 3
to 4 hours for the relief of pain. There are no satisfactory
"muscle relaxants" for use in disc disease, but a minor
tranquilizer such as diazepam, 2 to 10 mg given two to
four times daily for two to three days may be helpful.
Local heat application for the relief of muscle spasms is
advised but should be limited to mild heat for periods of
no longer than 20 to 30 minutes. Longer periods tend to
increase muscle irritability as the heat accumulates, and
Disc DISEASE / 419
increased muscle blood ﬂow occurs. Generally, after
four to five days of this management, the patient will
experience greater intervals of asymptomatic arnbula—
tion and can resume relatively normal activity within 10
days to 2 weeks. The patient should be advised to avoid
heavy lifting and straining for an additional two weeks.
At that time, attention should be given to factors contrib-
uting to the underlying musculoskeletal deficits responsi-
ble for the patient's disc disease. These usually stem from
obesity, poor muscle tone, and poor work habits. Proper
diet and an appropriate, enjoyable exercise, such as
swimming, dancing, tennis, or some other activity, can
be prescribed.
Certain symptoms and signs are indications for hospi-
talization. If the initial history and exam discloses a sig-
nificant neurologic deficit, particularly motor and blad-
der dysfunction, the patient should be admitted. By the
same token, hospitalization should be considered if de-
spite conscientious home treatment the patient's syrnp—
toms do not improve, if the patient is unable to return to
normal activity because of a recurrence of symptoms
with each period of ambulation, or if the home environ-
ment is such that adequate home management is not
possible. Whatever the reason for hospitalization in such
cases, the initial hospital care should be the same as
would be prescribed at home. The medical and nursing
staff should pay special attention to the patient's descrip-
tion of his or her pain, to evidence of changing neuro-
logic deficits, and to the pattern of requests for 1nedica—
tion, in order to evaluate the causes and severity of the
patient's disability.
In most instances, an acute presentation of severe pain
with a significant neurologic deficit warrants immediate
hospitalization. However, rarely is immediate surgery
required for herniations at the L4—L5 or L5—Sl level. Re-
covery will ahnost always occur in such cases, even with
a major herniation. A period of observation will usually
indicate that bladder dysfunction is primarily the result
of pain and not ofprimary nervous system injury. Even a
major foot drop will begin to diminish in a few days with
the nonsurgical regimen outlined. The dogmatism of
this advice must be modified when dealing with lesions
of an upper lumbar intervertebral disc. When major
symptoms and signs are associated with ruptures in this
area, protracted delay will afford the patient less chance
of recovery, especially if the conus of the spinal cord is
compressed. The decision to intervene surgically must
be made individually, on the basis ofthe acuteness of the
presentation, the severity of the deficit, and the patient's
general medical condition.
Diagnostic Studies.
General Laboratory Studies
The basic laboratory studies in cases of disc disease
include a hemoglobin measurement, hematocrit, and

420 / CHAPTER 20
erythrocyte sedimentation rate (ESR). The differential
diagnosis of back pain with or without leg pain, espe-
cially if the pain is chronic, must include neoplasia and
those chronic diseases revealed by anemia. The ESR will
be elevated in neoplasia, in a wide variety of inﬂamma-
tory disorders such as infection (discitis), and in rheuma-
toid spondylosis. The ESR will be normal in degenera-
tive intervertebral lumbar disc disease with or without
rupture. If the patient is being considered for surgery,
appropriate screening tests should include a platelet
count, a prothrombin time test, and a partial tl1rombo—
plastin time test.
Special Diagnostic Studies
In this age of rapidly advancing medical technology,
the neurosurgeon has available several diagnostic study
modalities for evaluating the status of the lumbar inter-
vertebral disc. These include roentgenography of the
lumbar spine, electromyography, bone radionuclide
scanning, venography, discography, myelography, body
computed tomography (CT), and magnetic resonance
imaging (MRI). A considerable amount of useful infor-
mation will be obtained by reviewing plain films of the
lumbar spine. Spondylosis, especially beyond that ex-
pected for the age of the patient, and disc—space narrow-
ing will suggest degenerative disc disease. Bony changes
of a chronic nature, such as erosion, sclerosis, or local-
ized areas of radiolucency will suggest disorders other
than intervertebral disc disease. Malalignment—scolio—
sis, excessive kyphosis, and subluxation—will suggest
congenital disorders or/6ld trauma. Careful inspection
for such specific evidence of congenital disease as spon-
dylolisthesis, spina biﬁda, and spondylosis (although this
may be secondary to trauma) may yield information
helpful in understanding the patient's symptomatology.
The usual findings in patients with ruptured interverte-
bral disc disease of the lumbar spine are minimal at best
and consist primarily of spondylosis and disc—space
narrowing. Polytomography should be limited to delin-
eating the true nature of localized lesions found on plain
films.
Despite its widespread use, electromyography is of lit-
tle value in the diagnosis of the typical case of a ruptured
intervertebral disc because of its lack of specificity. And
although in skilled hands it is quite accurate in delineat-
ing a single—root radiculopathy, it does so with no greater
accuracy than a careful history and physical exa1nina—
tion. Electromyography may be of value in those cases of
disc disease in which the history and physical exarnina—
tion do not suggest the diagnosis of a ruptured disc, or
those in which the differential diagnosis includes other
forms of neuropathy. It can be misleading in the patient
who has had a prior laminectomy with or without disc
excision. In such instances, abnormal findings will per-
sist indefinitely in both the paraspinous muscles and the
extremity muscles innervated by the previously involved
root (20).
Radionuclide scanning of the spine may also be help-
ful in diagnosing disc disease but, like electromyography,
may be misleading. The bone scan may be locally posi-
tive in a wide variety of active processes, including neo-
plasia, acute trauma, surgical healing, and infection. Al-
though a radionuclide scan is not usually positive in
degenerative disc disease or in the case of a ruptured disc,
it may be positive in spondylosis (21).
Lumbar epidural venography, or phlebography, may
be useful in identifying the site of rupture of a lumbar
disc (22). This technique involves the opacification of
the epidural venous system by the selective catheteriza—
tion of ascending lumbar veins. A unilateral displace-
ment of the antero—internal and sometimes the antero—
external venous channels may be produced by lateral
disc herniations. Venography is felt to be of value when
myelography is rendered inadequate by an enlarged
dural sac, an extremely lateral herniation, or arachnoid-
itis. It is not of value in patients who have undergone
surgery in the epidural space. Furthermore, while venog-
raphy is accurate in the patient with the typical ruptured
disc syndrome who has had no previous surgery, the in-
constant nature of the epidural venous anatomy makes
it of dubious value in the atypical case.
Enthusiasm for lumbar discography has waxed and
waned since its introduction by Eindeblom in 1948. It
involves the injection of l to 5 cc of a radio—opaque
water—soluble contrast medium into the region of the nu-
cleus pulposus through a 20—gauge spinal needle inserted
percutaneously. Its proponents argue that it can give
valuable information concerning the anatomical status
of the disc and can differentiate between a normal disc, a
degenerative disc, and a ruptured disc (23).
In a lumbar discogram, the extrusion of contrast me-
dium through the annulus into the epidural space sug-
gests the presence of a ruptured disc. If the procedure is
performed under local anesthesia and the injection is
associated with reproduction of the patient's pain, this is
felt to confirm disc rupture. The opponents of discog-
raphy as a diagnostic procedure argue that the introduc-
tion of a needle into a normal nucleus pulposus may
result in hastened degeneration or later rupture of the
punctured disc, or both. Moreover, no criteria exist for
distinguishing the asymptomatic degenerative disc from
the symptomatic degenerative disc on the basis of discog-
raphy; patients asymptomatic for lumbar disc disease
may exhibit the extrusion of contrast medium into the
epidural space (24). Beyond this, studies correlating the
accuracy of the pain reproduced in lumbar discography
as a diagnostic entity have not been generally accepted as
valid. If the efficacy of the treatment of disc disease by
percutaneous discectomy or the intradiscal injection of

chimopapain, collagenase, or steroids is established, dis-
cography will require further evaluation.
Myelography has been the mainstay of radiographic
evaluation of a suspected lumbar disc herniation. lo-
hexol has replaced metrizamide and iophendylate as a
contrast medium because it produces fewer untoward
effects (25). CT has earned a prominent role in the evalu-
ation of lumbar disc herniations and has been shown to
be effective in the demonstration not only of nerve roots
but also of the structures likely to compress them (26).
CT is more sensitive to lateral disc herniation than 1ny—
elography (27). In the patient with a straightforward disc
herniation syndrome, a CT that demonstrates nerve-
root compression at the appropriate site is sufficient to
plan therapy. If, however, the CT does not unequivoca-
bly reveal the pathology, myelography followed by CT
with the intrathecal contrast present should be under-
taken. This will allow visualization of the lower thoracic
and upper lumbar regions and can reveal unusual lesions
(e.g., tumors) as well as standard lumbar disc hernia-
tions.
Some authorities feel that it is not necessary to per-
form a myelogram or a CT prior to surgery in the typical
case of disc rupture. However, it must be pointed out
that while an L5 root syndrome (for example) is com-
monly caused by a posterolateral disc ruptured at L4—L5,
it may also be due to a more lateral disc ruptured at
L5—Sl. It is for this reason that patients with ruptured
discs usually undergo myelography or CT prior to disc
surgery. Additionally, myelography or CT may be used
to exclude the presence of a significant disc rupture in
patients with chronic pain simulating disc disease, but in
whom there are no neurologic findings. This indication
for such studies has widespread use for patients whose
lives are cornphcated by personal hability litigation or
job—related compensation claims.
MRI holds promise of largely replacing myelography
and CT (28/‘9). MRI offers excellent resolution, free-
dom frorn (ztone artifact, and the ability to image the
spine in any plane. High cost and long acquisition time
are problems to be surmounted, but MRI is rapidly be-
coming the imaging method of choice for diagnosing
disc disease.
Surgery
The primary indication for the surgical treatment of
disc disease is the failure of conservative management
and it occurs in three clinical settings. In the first of these,
involving the patient who presents with an acute disc
rupture associated with a severe neurological deficit, the
neurosurgeon may be required to proceed urgently. This
will rarely occur, but when it does, immediate surgery is
indicated. This situation is more likely to exist with rup-
tures of the upper lumbar discs. The patient will present
Disc DISEASE / 421
with back and leg pain, often bilateral, as well as parapa—
resis and urinary retention.
The patient for whom surgery is most commonly indi-
cated will be the one who presents with a typical history
of acute or chronic back and leg symptoms. The exami-
nation will reveal mild evidence of radiculopathy, in-
cluding hypesthesia, reﬂex depression, and mild weak-
ness. The patient will have had recurrent bouts of mild
disability culminating in a more significant episode re-
quiring hospitalization. After appropriate conservative
management, extending to 10 days or so, it will be clear
that httle progress is occurring.
The indication for surgery in the third type of patient
is more controversial. This is the patient who has re-
peated bouts of disability characterized primarily by
back pain, with occasional paresthesias or pain in the leg.
The course of the disease in such cases is protracted,
sometimes extending to many months or years. Yet
while the patient is repeatedly able to describe a quasi-
dermatomal distribution of the pain or paresthesias, ob-
jective findings of weakness and reﬂex changes are in-
consistently noted. For many reasons, primarily
socioeconomic, the patient is finally admitted to the hos-
pital, where studies reveal a questionable epidural defect
at the appropriate level. In this case, the decision whether
or not to operate is a highly individualistic one in which
the physician must consider not only the medical facts
but the effect of the recurring disability on the patient,
and on his or her work and private life. Moreover, the
physician, while remaining as objective as possible, must
also keep in mind that neurosurgery, no less than all
disciplines of medicine, is as much an art as a science.
Since most surgery for ruptured lumbar intervertebral
discs is done electively on relatively healthy individuals,
it involves the usual presurgical evaluations. Assurance
is obtained of a normal physiological cardiorespiratory
and hematologic status of the patient. Appropriate con-
sultation is rnade with the anesthesiologist, depending
upon the type of anesthesia to be used. While some sur-
geons prefer the use of local, spinal, or epidural anesthe-
sia (30,3l), general anesthesia is preferred by most sur-
geons for lumbar disc surgery. This involves the use of
intravenous pentothal supplemented by various 1nix—
tures of nitrous oxide, oxygen, and isoﬂurane delivered
through an endotracheal tube. Blood replacement is
rarely necessary during the surgery. Nevertheless, either
2 units of packed red blood cells should be available in
the operating room or the blood bank should perform
preoperative typing and antibody screening of the pa-
tient in the event that blood replacement becomes neces-
sary (32).
Procedure
Various techniques and positions for the surgical
treatment of lumbar disc disease have their advocates.

422 / CHAPTER 20
We prefer a hemilaminotomy and foraminotomy, with
the excision of a modest amount of disc material. I1n1ne—
diately before the operation, the patient is asked to con-
firm the side on which he has leg pain, and the 1nyelo—
gram films (if obtained) are arranged on the view box in
the operating room as if the spine were viewed from pos-
terior, corresponding to the operative field with the pa-
tient prone. The patient is then intubated under general
anesthesia and put in the prone position on either blan-
ket rolls 4 to 6 inches in diameter extending from the
shoulders to the iliac crests or on a frame of similar di-
mensions. The table is ﬂexed slightly so that the normal
lumbar lordosis of the spine is ﬂattened or reversed. A
midline incision is made from the spinous process above
the involved level to the level below. Skin—edge hemosta-
sis is obtained with hemostatic clamps and bipolar coagu-
lation. Another midline incision is then made through
the lumbodorsal fascia overlying the exposed spinous
processes, and the paravertebral muscles are stripped
subperiosteally with appropriate elevators from the spi-
nous processes and laminae on the involved side. Retrac-
tion is subsequently maintained with a self—retaining re-
tractor. During the periosteal dissection and retraction
of the paravertebral muscles, it is sometimes helpful to
brieﬂy produce muscle relaxation with intravenous succi-
nylcholine or a deepened level of anesthesia.
After completion of the steps described above, a small
hemilaminotomy is accomplished, including in the re-
section the medial portion of the facet joint. The inter-
larninar ligament is incised longitudinally, then resected
sharply with a number 15 blade or an angled Kerrison
rongeur. A foraminotomy is done next, to allow more
gentle retraction of the nerve root. Exploration of the
epidural space is performed, and proper identification of
the nerve root is made. The offending disc abnormality
is identified, and the nerve root is gently retracted ine-
dially with an appropriate nerve—root retractor. If a free
disc fragment is identified, it is removed with the disc
rongeur. The disc space is then entered and, with ine-
diu1n—sized straight and angled curettes and upward—an—
gled rongeurs, the disc material from the postcrolateral
quadrant of the disc is removed. No attempt is made at
significant additional removal of intradiscal material.
Following adequate removal of disc material, the epi-
dural space is further explored, the wound is thoroughly
irrigated with saline. Some authorities have advocated
placing a small free graft of subcutaneous fat over the
root to replace the normal epidural fat and to try to pre-
vent the epidural scarring which has been demonstrated
in animal experiments (33). Hemostasis is obtained in
the epidural space by bipolar coagulation. The wound is
then closed in layers (muscle fascia, subcutaneous fat,
and skin), and a suitable dressing is applied. The patient
is taken to the recovery room, extubated at the discretion
of the anesthesiologist, and observed for approximately
2 hours. After this, the patient is taken to his room.
There is usually no reason to put the patient in an inten-
sive care unit postoperatively.
With excessively obese patients, the surgery for a rup-
tured disc may rnore easily be accomplished with the
patient in the lateral position, with the involved side fac-
ing up and the table ﬂexed in the middle as with the
prone position. This position prevents the compromise
of diaphragm movement due to abdominal co1npres—
sion. It is, however, somewhat more difficult for the as-
sistant. Technically the operation is performed in a1nan—
ner similar to that described above.
Another frequently used position for surgery is the
knee—chest position. The purpose of this position is to
avoid any abdominal pressure whatsoever and thus de-
crease epidural bleeding.
Concerns ofpossible transmission of human i1nrnuno—
deﬁciency virus with the transfusion of blood products
have prompted use of methods available to minimize
intraoperative blood loss. However, blood loss is usually
limited to less than 100 cc using standard positioning.
Some surgeons feel that the knee—chest position may pro-
duce a tourniquet effect on the muscles of the lower ex-
tremities, resulting in damage to muscles with the release
of myoglobin, which may be renotoxic (34).
Variations in the surgical technique will depend upon
the training and experience of the surgeon. Some prefer a
much smaller incision than that described above, with
microscopic epidural dissection and removal of the disc
(35). It is suggested that the smaller wound makes for
quicker healing and less scar formation. The use of intra-
operative magnification with loupes or a microscope will
result in less chance of trauma to veins and the dura, but
the value of 1nicro—incisions is not proven.
Postoperative Care
Postoperatively, the patient is permitted food and ain-
bulation as tolerated. The sutures are removed in five to
six days, and the patient is discharged from the hospital
by the third to sixth day. For two to three weeks thereaf-
ter, the patient is permitted to ambulate to whatever de-
gree is comfortable, but with the intensity ofhis physical
activity limited to that which was practiced in the hospi-
tal. Sorne surgeons prescribe physical therapy and exer-
cise almost immediately after surgery; however, we do
not think that this is wise. The patient is at risk for addi-
tional disc herniation during the first month postopera-
tively since complete removal of all disc material from
the interspace is not possible, and the process of old col-
lagen lysis and new collagen synthesis results in a signiﬁ-
cant gain in tensile strength between the fifth and seven-
teenth days postoperatively, with a slower addition of
strength for another 10 days (36). At the end of one
month, depending upon how the patient is progressing,
an additional two to four weeks of increasing physical
activity is prescribed. The patient who has employment

in an office environment can usually return to work by
three to eight weeks postoperatively. It may take two to
four months for a person in a strenuous occupation to
resume work. During this period of convalescence, the
patient normally requires little if any pain—relieving med-
ication. With this regimen, patients with a ruptured lum-
bar intervertebral disc who have undergone surgery have
a 90 percent chance of a successful return to work and a
long—term asymptomatic postoperative course (37).
Causes of Failure
The major causes of failure of the surgical treatment of
a ruptured disc are improper diagnosis and improper
selection of patients for surgical treatment. The longer
the duration of the patient's symptoms (in terms of
months or years), the more "soft" the symptoms and
signs, the less definite the radiographic defect, and the
less impressive the disc herniation at surgery, the less
likely it is that the surgeon can expect a cure.
Complications
Other than a low incidence of wound infection (less
than 1 percent), serious complications of disc surgery
should virtually never occur. Nevertheless, there are cer-
tain operative complications that can occur. One serious
complication of surgery is nerve—root injury. This can
range from nerve contusion resulting in temporary post-
operative worsening of the patient's neurologic deficit, to
laceration of the nerve root and permanent damage. In-
jury to the nerve is most likely to occur while the inter-
larninar ligament is being sharply excised either with a
knife blade or a curette, or when the foraminotomy is
being performed with rongeurs. It is therefore imperative
that the surgeon identify the nerve root as soon as possi-
ble, and either keep it in direct vision at all times or cover
it with a cotton pledget so that he knows where it is.
Perineural adhesions resulting from chronic compres-
sion of the nerve root by disc material may make it diffi-
cult to dissect the nerve root away from the disc. This can
best be accomplished by identifying normal dura and
nerve root distal to the site of the adhesions and then,
under magnification and with excellent lighting, dissect-
ing away the adhesions. If a large disc fragment hes me-
dial to the nerve root, attempts to retract the nerve root
medially over the fragment may cause a stretch injury of
the root. The surgeon should first decompress the nerve
root by removing all disc material from the axilla of the
nerve (i.e., from between the medial aspect of the nerve
root and the dura as the nerve root proceeds distally
from the point at which it exits from the dural canal).
Tearing of the dura and arachnoid, which often occurs
as only a pinhole—sized opening or injury, may lead to a
Disc DISEASE / 423
cerebrospinal fluid leak or a pseudomeningocele. Extra-
dural bleeding during exposure of the nerve root or dur-
ing disc removal should not be controlled by excessive
packing of sponges into the epidural space. This may
result in injury not only to the root but also to other
intradural structures. The surgeon should notify the anes-
thesiologist of the difficulty so that the latter can prepare
for blood replacement if necessary. With good lighting,
bipolar cautery forceps, and magnification with loupes
or, in certain cases, the operating microscope, epidural
veins can almost always be coagulated before bleeding
occurs. If bleeding occurs, the source will usually be a
single large epidural vein lying in the anterior lateral epi-
dural space. The vein may lie in the lateral recess (under-
lying the partially resected facet joint), where it may be
injured by the rongeur during the bony resection. In this
case, the bleeding can easily be controlled by temporarily
packing into the lateral recess a small piece of absorbable
hemostatic material held by a small (5 x 5 mm) cotton
pledget. The total blood loss in most disc operations
should be no more than 100 to 150 cc, and is often much
less.
Another serious complication of disc surgery is injury
to intra— abdominal structures, especially the great vessels
that lie in the prevertebral space (38). This is most likely
to occur with excision of the L4—L5 disc and to result
from perforation of the anterior longitudinal ligament
by a curette or rongeur. Laceration of an iliac artery or
vein is the characteristic injury. Vascular laceration may
be heralded by excessive blood presenting itself through
the intervertebral disc space. More common, however, is
a precipitous decrease in blood pressure and the develop-
ment of shock. Although this may occur during the oper-
ation, it is more likely to be seen at the termination of the
procedure as the patient is transferred from the operating
table to the recovery room cart, or at the time of the
patient's arrival in the recovery room. The treatment is
immediate abdominal exploration. Vascular injury may
also present months after disc surgery as an arteriove—
nous fistula between an iliac artery and vein (39). It
should be suspected with the development of unilateral
leg swelling, and varicosities may exist as well. Cardio-
megaly and heart failure may occur. A to—and—fro mur-
mur located in the lower portion of the abdomen is
pathognomonic of an abdominal arteriovenous fistula.
Treatment consists of the restoration of arterial conti-
nuity.
Rarely documented in the literature are cases of injury
to an abdominal organ, such as the ureter, bladder, or
ileum (40). Nothing occurs at the time of surgery to sug-
gest that such an injury has occurred. In the case of in-
jury to the ureter or bladder, the patient may have post-
operative hematuria. With injury to the ileum,
prolonged ileus is generally seen, followed by the develop-
ment of signs of peritonitis within a few days. Appro-
priate management depends upon the organ injured.

424 / CHAPTER 20
Proper consultation should be obtained as soon as the
possibility of this complication enters the surgeon's
mind.
The role of spinal fusion in intervertebral disc disease
is currently less controversial than in the past. It is not
indicated during the first operation for a single ruptured
intervertebral disc. Patients who do not undergo fusion
have a better long—term outcome than those who do (4 1).
This is the case even if spondylolisthesis, whether congen-
ital or degenerative, exists. Fusion is indicated in young
patients with spondylolisthesis who have clear syrnp—
toms and signs of mechanical instability, and in whom
degenerative changes are limited to a single level. Fusion
is also indicated in some cases in which decompression
itself has resulted in facet instability (42). The patient
who has had multiple back operations at multiple levels,
with bilateral laminectomies and forarninotornies, and
who develops instability should be considered for fusion
(43). Fusion is currently also being recommended for
some patients with single—level degenerative disc disease
who do not have true disc rupture or herniation. These
patients are usually young and have had occupations
that have rendered their backs more susceptible to
trauma, or have had a specific traumatic episode from
which their back pain dates. They have no neurologic
deficits and their myelogram is normal. The discogram
shows a single degenerated disc that appears to be dis-
eased out of proportion to the disease of adj acent discs or
to the age of the patient. Initial follow—up studies on such
patients suggest that they experience a reduction of
symptoms and return to a more active social existence
following fusion. However, there has not yet been ade-
quate long—term follow—up of a large series of such cases.
Chemonucleolysis
A proteolytic enzyme, chymopapain, has been advo-
cated for the enzymatic digestion of lumbar interverte-
bral disc material, a procedure termed chemonucleoly—
sis. It has been reported to be effective in approximately
65 percent of patients with physical symptoms and signs
and radiographic (including myelographic) evidence of
lumbar disc disease (37). The procedure is not used for
cervical disc disease. The mechanism of action of the
enzyme is unknown, but it is ineffective in vitro against
extruded disc material. The apparent effectiveness of the
enzyme may relate to its known neurolytic activity on
poorly myelinated nerve fibers (44) of the type found in
the posterior longitudinal ligament and annulus (which
may be pain ﬁbers) (8) rather than on digestion of the
disc itself. The chymopapain procedure has been asso-
ciated with a number of serious complications. Anaphy—
laxis occurs in about 0.5 percent of injections with a
mortality rate of 0.06 percent. Additionally, a number of
patients have developed a delayed paraplegia from trans-
verse inyelitis two or three weeks after the procedure.
Due to these complications, most surgeons have aban-
doned chymopapain (45).
Percutaneous Nuclectomy
Recently, a new surgical technique called percutane-
ous rmdectomy has been introduced (46). To perform
this procedure, a 2—1n1n blunt—tipped suction—cutting de-
vice is passed percutaneously via a posterolateral ap-
proach into the disc space. Disc material is removed only
from inside the disc space. Although this technique is
inadequate for the treatment of a substantially herniated
or extruded disc, it may hold promise for the treatment
of a herniation into the layers of the annulus (47). In
such cases, the back and leg pain is referred from annular
pain fibers. It could be reasoned that decompressing the
disc space would relieve pressure on the annular hernia-
tion and relieve the pain. Experience has not yet per1nit—
ted an analysis of the long—term results or complications
of the procedure.
Reoperation
The consideration of reoperation for disc disease sug-
gests in most instances that the initial diagnosis was in-
correct (48). However, there are times when the original
surgery was properly undertaken but was incomplete.
Patients who postoperatively exhibit no change in their
signs and symptoms may, for example, have retained
extruded disc fragments. This is likely if the surgeon
found a ruptured disc with some extruded fragments at
the time of surgery. The retained fragments will usually
be found quite laterally, often in the foramen. Patients
who have an acute recurrence of their preoperative signs
and symptoms in the first two to three weeks postopera-
tively should be suspected of having extruded an addi-
tional fragment frorn a surgically treated intervertebral
disc. Additionally, a recurrence of intervertebral disc
rupture may occur months or years after an earlier disc
operation. In such instances, the patient should be inan-
aged in the same way as for a primary attack. Reopera—
tion on the spine is complicated by the presence of epidu-
ral scarring from previous operations. But since the
surgeon can proceed safely into the distorted, scaired
area only after proper orientation, made possible by ex-
posing the normal anatomy of the spine, surgery should
begin by exposing this normal anatomy, including the
epidural space, at the extremes of the scaired anatomy.
Testing both the surgeon's patience and understand-
ing ofback disorders will be the patient who either never
returns to work postoperatively or, following recovery,
returns to work only to note vague symptoms of back
and leg pain with activity, similar to but not quite the
same as the preoperative symptoms. Such patients often
either have no neurologic deficit or may have a de-

pressed deep tendon reﬂex and minor derrnatornal sen-
sory loss—findings present since the initial evaluation.
These patients will want "something done" and will
have settled any litigation involved in their injury. The
electrornyograrn (EMG) in such cases will probably be
abnormal, and the myelogram will be interpreted, at the
very least, as consistent with "postoperative change."
These patients should not be explored; "exploration"
means the surgeon does not know what to expect to find
and, in all likelihood, will therefore not "find" the pa-
tient's problem. Instead, such patients must be managed
with compassion but firmness. Their life—styles should be
examined for any factors contributing to their syrnp-
toms. They may have to change their occupation. Pro-
grams of dieting, exercise, and adjuvant therapy utilizing
all modalities employed by the physical therapist must
be undertaken in such cases. Steroidal and nonsteroidal
anti-inflarnrnatory agents, administered orally, and anti-
depressant drugs may provide some pain relief. Above
all, the physician should support the patient psychologi-
cally. These patients will ultimately carry the diagnosis
of arachnoiditis, facet syndrome, spinal stenosis with epi-
dural fibrosis, or others. They may ultimately enter corn-
prehensive pain-control programs, a discussion of which
is beyond the scope of this chapter.
Unusual Herniations
Two unusual types of lumbar disc herniation may be
encountered by the surgeon: the intradural rupture of a
disc and the simultaneous rupture of multiple discs. The
ruptured lumbar intervertebral disc may rarely be found
within the subdural or subarachnoid space (49). The pa-
tient will usually have a long history of persistent back
pain, with intermittent leg pain that may be unilateral or
bilateral. The presenting episode is acute in nature and is
associated with signs of significant cauda equina corn-
pression, including paresis (unilateral or bilateral), rnulti-
level sensory deficits, and bladder dysfunction (retention
or incontinence). The patient will not improve with a
few days of bed rest. The myelogram or CT reveals an
intradural mass at the level of the disc space. The rup-
tured intradural disc should be approached with a bilat-
eral larninectorny and transdural excision. It is not clear
why this injury occurs, but one can postulate that a rnid-
line-bulging or partially extruded disc causes adhesions
to the dura, with dural thinning. Subsequent complete
extrusion of the disc then ruptures through the weakened
dura. Most such ruptures occur at the L4-L5 interspace.
While the true incidence of multiple disc ruptures is
impossible to obtain from the literature, it certainly
comprises less than 5 percent of all cases of disc rupture
(15). The vast majority of multiple ruptures are unilat-
eral and occur at the L4-L5 and L5—Sl levels. In such
cases, one of the disc ruptures may be more midline than
Disc DISEASE / 425
the other. Rarely are extruded fragments found at both
levels. Usually there is a recognized precipitating event,
such as heavy lifting. The clinical signs indicate that
more than one level is involved, and myelography or CT
reveals the appropriate extradural defects. Rather than
myelography or CT, some surgeons recommend the rou-
tine surgical exploration of the lower two disc spaces (L4-
L5 and L5—Sl), even if only one level is clinically sus-
pected of being injured. If the surgeon determines that
both levels are involved, each level should be handled
technically as in the patient with a single disc rupture,
and the postoperative management should also be the
same. We have operated on one patient, a 36-year-old
man presenting with an acute cauda equina syndrome
following heavy lifting, who had an extruded fragment at
L4-L5 on the right and an intradural midline rupture at
L5—Sl. Postoperatively, the patient returned to his
previous occupation in four months with no neurologic
deficit.
CERVICAL DISC DISEASE
General Considerations
The term cervical disc disease covers several chnico-
pathologic entities. The "soft" or herniated (protruding
or extruding) disc presents with acute and chronic syn-
dromes similar to those resulting from a ruptured lurn-
bar intervertebral disc. The "hard" or osteophytic disc
syndrome is known as spondylitic disc disease and will
be covered in the chapter on spinal stenosis.
There is considerable disagreement in the literature
about the relative frequencies with which the neurosurg-
eon will see the "soft" or herniated disc and the "hard"
or spondylitic disc. The older literature suggests that the
herniated disc is much more common, while more re-
cent literature suggests a predominance of cervical disc
disease as the result of spondylosis. The latter has been
our experience.
Except for a few specific considerations, the anatomy,
pathology, and biomechanics of the cervical disc are
clinically similar to those of the lumbar disc. Although
the cervical disc is not subjected to the same loading
stresses that occur in the lumbar spine, the greater rnobil-
ity of the cervical spine results in a rate of degeneration
of the cervical disc which matches, for the age of the
patient, that of the lumbar disc. The rate of degeneration
of the C5-C6 and C6-C7 discs is much greater than that
of the other cervical discs, and more than 90 percent of
the clinical syndromes of cervical disc disease are asso-
ciated with disease at these two interspaces.
Symptoms
As with the ruptured lumbar intervertebral disc, the
ruptured cervical disc may present with two basic symp-

426 / CHAPTER 20
tom complexes: acute and chronic. With the acute rup-
ture of a cervical disc, the patient will invariably note a
speciﬁc time of onset. Little trauma may be experienced;
a large number of patients appear to develop the syrnp-
toms of such a rupture during sleep, perhaps due to tor-
sion of the neck when turning in sleep. The symptoms of
the chronic complex are more insidious in onset. How-
ever, a careful analysis reveals the complaints to be quite
similar, except for their rate of onset, to those of the
patient with an acute rupture. The laterally herniated
cervical disc will produce unilateral neck pain radiating
to the medial aspect of the scapula and into the upper
extremity. The pain will be associated with isolated ino-
tor and reﬂex deficits, determined by the level of the
rupture. There is a variable degree of upper anterior
chest pain. Compression of the head from above will
exacerbate the pain, especially if the latter is associated
with a lateral rotation and extension component of neck
movement. The pain is relieved by traction.
The most impressive complaint of the patient with a
ruptured cervical disc relates to the pain and not to the
accompanying motor weakness. The pain is constant
and tends to prevent sleep. As opposed to most lumbar
disc ruptures, the patient with a cervical disc rupture
often can find no comfortable position, although occa-
sionally flexing the neck to the opposite side and holding
the ipsilateral hand and arm resting on the head will give
relief akin to that produced by ﬂexing the leg in lumbar
disc disease.
Spontaneous midline cervical disc herniations are ex-
tremely rare in the absence of trauma sufficient to pro-
duce a fracture dislocation (50). The patient with such a
herniation may complain of sudden posterior and rnid-
line neck pain. There may be some radiation of the pain
into the shoulders and interscapular area. Anterior chest
pain is usually not a feature of midline herniations. Also,
although a large rupture may be associated with an acute
myelopathy, there is usually little spinal cord dysfunc-
tion in these cases. They may present with Lhermitte's
sign, a "shock"-like radiation of pain down the midline
and into the lower extremities with neck ﬂexion.
Differential Diagnosis
The symptoms and signs of an acutely ruptured cervi-
cal disc are so characteristic that the physician will have
little trouble in making the diagnosis. However, the pa-
tient who presents with a chronic history may present a
problem in diagnosis (10). Nerve—root—related spinal tu-
mors such as neurofibrornas or rneningiornas will cause
a long history of symptoms of gradually increasing sever-
ity. The motor deﬁcit in such cases may be more prorni-
nent than with the ruptured disc, and the pain less prorni-
nent. Symptoms of myelopathy may be more prominent
than with a lateral cervical disc rupture. The changes
seen on plain x—ray films and the rnyelographic defects
are both often characteristic of these tumors. Intra1nedul-
lary neoplasms and cervical syringomyelia will usually
present with a chronic syndrome of weakness and atro-
phy in the upper extremities, and spastic paraparesis.
When pain is present, the clinical differentiation of these
conditions from myelopathy secondary to cervical disc
disease may be difficult.
Spillane's neuritis, or neuritic amyotrophy, is usually
unilateral and most often involves the C5 root. Although
the pain is disconcerting, it is generally not as severe as
that produced by acute nerve—root compression. The
pain develops gradually over a few days, then subsides
over an additional few days. It is associated with marked
paresis, usually greater than that seen with nerve—root
compression by a ruptured disc. The symptoms of le-
sions of the brachial plexus, such as those produced by a
neurofibroma, Pancoast's tumor, or thoracic outlet syn-
drome are only superficially similar to those of disc dis-
ease. The pain and paresthesias are not in a root distribu-
tion, are unrelated to motion of the neck, and are usually
reproducible by local compression of the brachial
plexus. Additionally, Homer's syndrome may be seen in
cases of Pancoast's tumor.
Tardy ulnar nerve palsy and carpal tunnel syndrome
usually will not be confused with cervical disc disease.
They are not related to neck movements, and the pain is
usually in the distribution of the nerve, with percussion
at the point of the local compression exacerbating the
symptoms. Occasionally there may be a distribution of
pain proximal to the point of compression of the ulnar
nerve or the median nerve, radiating up the arm. How-
ever, this rarely reaches the shoulder and does not pro-
duce symptoms in the scapula or anterior chest. Thus,
one should have no difficulty in distinguishing nerve
compression from cervical disc disease or from internal
derangements of the shoulder, which occur with adhe-
sive capsulitis, tendonitis, and injury to the rotator cuff.
The relationship between the pain and movement of the
neck and shoulder will aid in this differentiation.
Localization
Ninety percent of disc ruptures occur at C5-C6 and
C6-C7. A small number of ruptures occur, in equal fre-
quency, at C4-C5 and C7-Tl. Scoville reported that 1
percent of ruptures occur at C3-C4 (51). We know of no
reports of spontaneous ruptures at C2-C3.
Unlike herniations in the lumbar area, cervical hernia-
tions at a specific cervical interspace compress the root
exiting at the foramen made by the articulations of that
interspace. Therefore, a herniation at C4-C5 compresses
the C5 root, which exits at the C4-C5 foramen. With a
C4-C5 rupture compressing the C5 root, the symptoms
are primarily in the deltoid region of the lateral aspect of

the upper arm. One will note weakness of the supraspin—
atus, infraspinatus, and deltoid muscles. The biceps
muscle may be weak. Deep tendon reﬂexes may be di-
minished in the biceps and brachioradialis. Ruptures at
IC5—C6 with C6 nerve root compression result in pain
and paresthesias extending into the lateral aspect of the
proximal arm and into the dorsum of the forearm. Char-
acteristically, the pain and paresthesias extend to the
thumb and index finger. There may be mild to moderate
weakness of the biceps and brachioradialis muscles. Oc-
casionally the only weakness noted will be that of the
extensor carpi radialis. The reﬂexes of the biceps and
brachioradialis may be diminished or absent.
With C6-C7 ruptures (which affect the C7 root), the
sensory symptoms are found in the index and middle
fingers. Weakness of the triceps is noted, as is a dirnin—
ished reﬂex in that muscle. The C8 root is compromised
with a C7—Tl rupture. The sensory symptoms of a rup-
ture at this level are found in the ulnar aspect of the
upper arm and forearm, with radiation into the ring and
little fingers. Weakness is noted in all extensor muscles
of the wrist except for the extensor carpi radialis, in all
ﬂexors except the carpi radialis and palmaris longus, and
in all intrinsic muscles of the hand. The triceps reﬂex
may be diminished, as may the finger ﬂexor reﬂexes.
Diagnostic Studies
With regard to the diagnostic study of cervical disc
disease, little can be added to the information presented
in the discussion of lumbar disc disease. The electromyo—
grarn may be more helpful here, especially when per-
formed in conjunction with nerve—conduction timing in
patients with disorders of the brachial plexus, tardy ulnar
palsy, and carpal tunnel syndrome. However, peripheral
nerve conduction may be delayed with the chronic corn-
pression of nerve roots. Discography and venography are
of no help.
A few surgeons believe that the clinical syndromes of
cervical disc disease are so diagnostic that myelography
or other suitable studies, namely CT and MRI, are not
indicated. However, most prefer the aid of localizing
studies. This is because the brachial plexus may be pre-
or postfixed. In the prefixed plexus, the neural cornpo—
nents of the plexus are shifted upwards, with the effect
that there is a greater contribution to the plexus by C4. In
the postfixed plexus, there is a greater contribution by
T2. This can have bearing on the patient's subsequent
neurologic deficit. For example, in a preﬁxed plexus the
biceps receives more innervation from C5, while in a
postﬁxed plexus it receives more innervation from C6.
Myelography or CT with intrathecal contrast is stan-
dard for evaluation of cervical radiculopathy. MRI has
been shown to offer accuracy rivaling that of contrast CT
with the advantage of being noninvasive (52).
Disc DISEASE / 427
Management
As in the case of lumbar disc disease, the majority of
patients with a cervical disc rupture, whether acute or
chronic, will respond satisfactorily to nonsurgical ther-
apy. This consists of reduced physical activity and sup-
portive measures during the symptomatic episode, fol-
lowed by proper rnusculoskeletal care. Patients are
advised to seek bed rest during the painful state. Cervical
traction through a halter device is most helpful. Gener-
ally, the attitude of the neck in traction is maintained
slightly ﬂexed. This permits the facet joints to open, en-
larging the foramen and decompressing the nerve. The
use of muscle relaxants and analgesics for the first two to
three days after rupture will be of help in relieving pain,
muscle spasm, and the boredom of bed rest. If for per-
sonal reasons the patient rnust be up and about periodi-
cally during this time, a firm cervical collar may be help-
ful. This reduces neck motion and the downward
compressive force of the head on the cervical disc. Soft
collars serve no purpose other than to advertise that the
patient has a neck disorder. As the patient becomes corn-
fortable with the upright position he or she may be per-
mitted increasing activity. However, as with lumbar disc
disease, it may take four to six weeks before the patient is
comfortable enough to resume full normal activities.
If the patient's symptoms persist despite traction or
are made worse by traction, one should consider an al-
ternative diagnosis. The most common diagnosis is sirn—
ply cervical myositis from ligament or muscle strain or
both, often associated with emotional tension. These pa-
tients are most difficult to manage, often being very de—|
pendent or having passive—aggressive personalities. The
physician must be patient and encouraging and not
make great use of medication. Requiring significant per-
sonal involvement by the patient is important. Unfortu-
nately this state is quite common in patients suffering
from "whiplash" injuries, especially if htigation is in-
volved.
Hospitalization may be required for the same reasons
noted in the management of patients with lumbar disc
disease, either because the home environment does not
permit adequate therapy or because the patient has a
significant neurologic deficit that warrants continued
close observation by the physician.
Surgery
The indications for the surgical treatment of cervical
disc disease are similar to those for surgery in ruptured
lumbar disc disease. The primary indication is a signifi-
cant neurologic deficit that has not improved within a
reasonable amount of time. It is difficult to quantitate
the adjectives "significant" and "reasonable"; this must
be individualized on the basis of the patient's state of

428 / CHAPTER 20
health and work requirements, and the physician's expe-
rience. Generally, a weakness of an acute or subacute
onset that prevents the patient from undertaking normal
daily activities and that does not improve in seven to ten
days fits this description. The persistence of pain requir-
ing large doses of medication is an indication for surgery
if the pain is clearly of root origin.
The operative approach will depend on many factors,
including the surgeon's training and operative experi-
ence. There are those who believe that the only approach
to the cervical disc is the posterior approach (50). Others
feel that the approach should only be made anteriorly
(53). We believe that the posterior approach should be
used in all patients who have a single—level lateral her-
niated (soft) cervical disc. The anterior approach is ap-
propriate for the single—level central herniated disc,
spondylotic ridge, and lateral osteophyte. Multiple levels
(more than two) of involvement, with bilateral radicular
syndromes or rnyelopathy, should be dealt with posteri-
orly. This is especially true if three or more levels are
associated with posterior ligarnenturn flavurn hyper-
trophy as seen on radiographic studies. These consider-
ations apply whether one is dealing with herniated cervi-
cal discs or spondylotic lesions.
The preoperative evaluation for cervical disc disease is
lhe same as for lumbar disc disease, and general anesthe-
sia is similarly used.
Procedure
For the posterior approach in the uncomplicated case
we prefer the sitting position. In elderly patients or those
with cardiovascular disease a prone position may be pre-
ferred. After induction of anesthesia, the patient is gradu-
ally raised to the sitting position with the head stabilized
in a suitable pinion head holder. The neck is kept in the
neutral position with the head slightly ﬂexed. A central
venous catheter is introduced into the right atrium for
aspiration in the case of air embolism, although rneticu—
lous attention to operative technique has resulted in no
clinically significant air embolism in our practice. The
technique involves the coagulation of large vessels before
they are electively cut, the immediate coagulation of all
smaller sectioned vessels, and the absence of any nega-
tive phase in mechanical ventilation (54).
A rnidline incision is made over the spinous process
bisecting the level of interest. For unilateral disease, the
paravertebral muscles are stripped subperiostially from
the spinous processes and laminae only on the appro-
priate side. An intraoperative x—ray may be used to iden-
tify the interspace if a limited incision that does not allow
the identification of C2 is used. Self—retaining retractors
are placed, and a hernilarninotorny is performed, using a
curette and a ronguer, in the adjacent laminae overlying
the appropriate nerve root. The nerve root is then identi-
fied and traced into the foramen, and a foraminotomy is
performed. If the nerve root is significantly compressed
within the foramen, the foraminotomy is performed
with a small electrically driven or air turbine drill. Corn-
pression is significant if a small nerve hook cannot be
easily passed into the forarnen alongside the root. The
foraminotomy is carried for 5 to 8 mm out along the
nerve root, depending upon the underlying pathology.
The use of magnification or the operating microscope is
often helpful during drilling and the subsequent disc re-
moval. The nerve root is retracted either cephalad or
caudad, according to the location of the disc herniation.
Rarely, there is a free disc fragment. However, with inci-
sion of the posterior longitudinal ligament such a frag-
ment will appear. In contrast to fragments generally
found in the lumbar area, those found in the cervical
region are rarely more than 2 to 3 mm in size, although
fragments as large as 5 mm may be encountered. No
effort is made to enter the intervertebral disc space. He-
rnostasis is obtained within the epidural space by bipolar
electrocautery. The wound is closed in layers, including
the skin, with nonabsorbable sutures. Copious irrigation
is utilized throughout the procedure.
If there is a central disc herniation and the choice is
made to treat it through a posterior approach, a bilateral
laminectomy is done involving the appropriate level and
the immediately adjacent upper and lower levels. While
in such cases the centrally ruptured disc fragment may
be removed through an extradural approach from one
side or the other, particularly if it is paracentral in loca-
tion and is associated with a lateralizing radiculopathy,
the surgeon must be prepared for a transdural excision.
The dura is opened in a paramedian manner. The appro-
priate dentate ligament is sectioned and utilized to
slightly rotate the cord, permitting visualization of the
site of protrusion of the ruptured disc through the ante-
rior dura. The dura is opened in a longitudinal manner
overlying the protrusion, and the disc material is re-
moved with the use of a small angled curette and a small
disc (pituitary—type) rongeur. If the arachnoid has not
been opened, it is not necessary to close the anterior
dural defect. The posterior dural incision is closed with
nonabsorbable sutures, and the wound is closed in
layers, as in the unilateral approach.
Upon completion of the surgery, the patient is ob-
served in the recovery room, and once returned to the
ward is permitted ambulation as tolerated. Although a
collar is not necessary, some patients report less pain
during their first few days of ambulation when a firm
collar is used. Transient symptoms related to the pres-
ence of the intraoperative endotrachcal tube, such as
coughing and discomfort on swallowing, are managed
syrnptornatically.
The anterior approach is also performed under general

endotracheal anesthesia. The patient is put in the supine
position, with a small towel roll posterior to the lower
neck and upper thorax. A central venous line is not neces-
sary in this approach (55). If an anterior cervical fusion is
to accompany the discectoiny, the bone for the graft is
taken from the ihac crest. The crest is elevated slightly by
the use of a small towel roll placed beneath the ipsilateral
buttock. Some surgeons prefer to make the skin incision
on the side of the disc extrusion. Being right—handed, we
always operate from the right side of the patient, making
the skin incision on that side, since the discs tend to be
oriented slightly cephalad from anterior to posterior.
Also to be considered is the fact that the thoracic duct is
at greater risk of injury if lower cervical discs are ap-
proached frorn the left side.
The skin incision is made through a natural skin
crease beginning at the rnidline and extending posterior
and cephalad. The initial incision is carried through the
subcutaneous tissue and the platysrna. Heinostasis is ob-
tained with the use of skin clips and cautery. The basic
plane of dissection lies between the sternocleidoinastoid
and omohyoid muscles laterally, and the sternohyoid
muscle medially. This plane is easily developed by blunt-
finger dissection until the anterior surfaces of the verte-
bral bodies are encountered. Further exposure is facili-
tated by the use of hand—held retractors. The pre vertebral
fascia is opened sharply, using bipolar cautery for the
occasional venous bleeding. A needle is placed in the disc
space suspected of being involved, and the location is
confirmed with a lateral x—ray.
If a bony fusion is to be done, a suitable bone plug is
removed from the iliac crest while the x—ray film is made
and developed. A 6—c1n incision is made overlying the
ihac crest, beginning anterior to the anterior gluteus ine-
dius muscle (53). A circular bone plug is removed from
the anterior iliac fossa just beneath the iliac crest. Bone
wax is not used for hemostasis; instead, the bone defect
and the soft—tissue wound are packed with a surgical
sponge, the tail of which is left outside the wound for
easy accountability. The graft wound is closed at the end
of the overall surgical procedure, while the neck wound
is being closed. This insures satisfactory deep—wound he-
rnostasis, reducing the incidence of postoperative hema-
torna and serorna formation, which can be a source of
annoyance to the patient.
If a rectangular segment of bone is to be used for the
cervical fusion [the Smith—Robinson technique (56)], the
ihac crest posterior to the anterior iliac spine is exposed
subperiosteally. An osteotoine is used to remove an ap-
propriate length of the ihac crest. Heinostasis is obtained
by packing until wound closure, which commences with
closure of the periosteum.
After the appropriate cervical disc interspace has been
identified by intraoperative x—ray, the longus colli rnus—
cles are cauterized along their attachments to the ante-
Disc DISEASE / 429
rior half of the superior vertebral body, the disc space,
and the anterior superior half of the inferior vertebral
body, and are elevated. A self—retaining retractor is
placed, the blades located deep to the muscles. The anes-
thesiologist palpates the ipsilateral superficial temporal
pulse to be certain that the carotid artery is not occluded
by the retractor. Although this cannot be universally re-
hed upon, obliteration of the pulse is significant. An inci-
sion is rnade through the anterior longitudinal ligament
into the disc, and the discectoiny is begun with curettes
and disc rongeurs. If the Cloward technique is used, the
anterior half of the middle of the disc is removed in this
fashion. The Cloward guard and an appropriate drill are
then used to make a drill hole into the remaining disc
space. If a lateral disc herniation is present, the drill is
offset slightly to the opposite side. This permits drilling
through to the anterior epidural space without the
danger ofpushing additional disc material through at the
site of the rupture and further compromising the nerve
root. If a central disc herniation is present, the drill is
placed inidline but is centered more into the inferior ver-
tebral body rather than being placed squarely over the
disc space. This permits drilling through the superior
aspect of the inferior body into the epidural space before
breaking through the disc at the site of rupture, a tech-
nique especially helpful if the epidural space at the disc
space is compromised by central osteophytes. This pro—»
cedure avoids the tendency to drive additional disc 1nate—
rial through the site of rupture into the epidural space
with the drill, which would create the risk of additional
cord compression.
During the drilling process with the Cloward drill, it is
imperative that the depth of the drill hole be inspected
frequently. With the aid ofgood lighting and one's tactile
sense, the surgeon should be able to detect when the drill
engages the cortical bone just prior to its entry into the
epidural space. The remainder of the bone is then re-
moved with a small curette. At this point, an intact poste-
rior longitudinal ligament may or may not be encoun-
tered since portions of the ligament are often removed
with the bone during the curetting process. The ligament
and additional bone are then removed with the use of
small angled Kerrison rongeurs, beginning in the inferior
aspect of the drilled defect. The surgeon works progres-
sively superior and lateral to either side, removing the
osteophytic material, the posterior longitudinal hga—
ment, and the disc material with angled curettes and
small angled Kerrison rongeurs. At this point, it is i1n—
portant to pay special attention to the degree of co1npres—
sion of the dura by the material to be removed. The
surgeon should not add to that compression by inserting
large instruments into the epidural space. We believe
that it is this action that results in most of the injuries to.
the spinal cord that occur during this procedure (57).
The injuries result either from direct compression of the

430 / CHAPTER 20
cord or from damage to the anterior spinal artery with
subsequent spinal cord infarction.
If the Cloward technique is not to be used, the disc
material is removed in its entirety with curettes and ron—
geurs, employing various modifications of the Smith-
Robertson technique (56). A disc—space spreader is help-
ful for visualization during the procedure, and posterior
or lateral osteophytes may be more easily removed with
a high—speed electric or air drill. We prefer the Cloward
technique simply because it permits better visualization
through the defect created by the Cloward drill. In the
other techniques, this advantage can be gained by the use
of magnification with appropriate lighting.
To fuse or not to fuse is a question currently debated
with some vigor in discussions of cervical disc surgery
(58). It is clear that spontaneous bone fusion can occur
even if bone is not implanted at the time of surgery,
although this will require a longer period than if a bone
graft is inserted. However, there is also evidence that fu-
sion of the disc space will result in an exacerbation of
degeneration in the adjacent disc spaces. This may be
due to an inability of the fused space to absorb its share
of the stress applied to the cervical spine, which must
then be absorbed by the adjacent disc spaces, increasing
their exposure to trauma. We prefer not to employ fu-
sion if the patient is under 50 years of age and does not
have significant evidence of degeneration at the adjacent
disc spaces as evidenced by disc—space narrowing and
asymptomatic osteophyte formation. There is no differ-
ence in the rate or extent of fusion with a round bone
graft (the Cloward technique) versus that with a rectangu-
lar graft (the Smith—Robertson technique).
Following completion of the surgical procedure, the
wound is closed in layers, including the skin. A small soft
rubber drain is left in the prevertebral space for 24 hours.
The patient is permitted food and ambulation as toler-
ated. A collar is not needed for stability, although some
patients feel more comfortable wearing a firm collar for
partial support of the head for a few days. Physical activ-
ity is resumed according to the patient's wishes. Most
patients are returned to full normal activity within four
to six weeks after surgery. Patients with manual occupa-
tions that require the use of the upper extremities, as in
heavy lifting, may require three months of convales-
cence before returning to work.
Complications
Several significant complications of the anterior ap-
proach have been reported. The most signiﬁcant one is
injury to the spinal cord, to which reference was made in
the discussion of technique. It should also be re1ne1n—
bered that a patient who has a small anteroposterior di-
ameter of the spinal canal, either congenitally or as the
result of spondylosis, is at risk during intubation if the
neck is subjected to extremes of ﬂexion or extension.
Additionally, injury to the cord can occur during the
insertion of the bone plug. This can be avoided by insur-
ing that the plug is cut to an appropriate size and is in-
serted with traction on the cervical spine so that it ulti-
mately rests snugly in its proper place when the traction
is released. The traction is produced by the anesthesiolo-
gist, who reaches under the drapes and pulls against the
angles of the mandible. Tapping of the bone should be
performed gently with the irnpactor partially overlying
the vertebral body above or below the disc space. A small
shelf of bone left posterior to the plug may protect
against posterior protrusion of the plug.
Injury to the esophagus may occur with sharp dissec-
tion in the prevertebral space or with the inappropriate
placement of a retractor blade with prongs. If such an
injury is suspected, it can be confirmed by applying an
anesthetic mask to the nose and mouth and exerting posi-
tive pressure while the wound is filled with saline solu-
tion. Bubbles will disclose the point of injury, which may
be repaired primarily with absorbable sutures. The
wound should be drained. An injury to the carotid artery
can occur if sharp dissection is used beneath the sterno—
cleidornastoid muscle into the prevertebral space. A ca-
rotid laceration may be repaired with appropriate 5-0 or
6-0 arterial sutures once proximal and distal control of
the bleeding has been obtained by the use of vascular
clamps. With the use of self—retaining retractors, the ca-
rotid artery may also be significantly compressed. There-
fore, the surgeon should use these retractors to the least
possible extent. This is one reason to place the retractors
beneath the elevated longus colli muscles.
Results
In patients who have undergone surgery for cervical
disc herniations, the long—term results with the anterior
approach do not differ from those with the posterior ap-
proach.
Good results, occurring in about 90 percent of pa-
tients, are probably achieved in a higher percentage of
cervical disc operations than lumbar disc operations. Re-
current herniations are rare. Also, although there is no
evidence that patients with cervical disc herniations at a
young age have an increased propensity to symptomatic
degenerative disc disease at a later age than do members
of the general population, an understanding of the patho-
physiology of disc degeneration would suggest that this is
possible. Therefore, both younger and older patients
should be instructed, as in lumbar disc disease, about
physical activity and work habits. This instruction will
depend upon the patient's habitus, current state of cervi-
cal disc degeneration, and occupation, and upon the ex-
perience of the physician.

THORACIC DISC DISEASE
General Considerations
Thoracic disc herniations are quite rare, representing
less than 1 percent of all disc herniations (59). However,
an examination of the literature published early in this
century, which led to the seminal conclusions of Mixter
and Barr, reveals that thoracic disc herniations, as well as
those of the cervical and lumbar area, were recognized.
The relative rigidity of the thoracic spine imparted by the
articulating ribs is thought to be the main factor in the
paucity of thoracic disc herniations; herniation is more
common in the lower thoracic spine, which has greater
mobility (60).
Presentation
As in cervical and lumbar disc disease, thoracic disc
herniations present in the form of acute or chronic
symptom complexes. They can occur spontaneously or
in association with minor trauma, such as heavy lifting
or a fall. The symptoms are primarily those of spinal axis
and thoracic radicular pain, with evidence of 1nyelopa—
thy being less frequent.
Acute lateral thoracic disc herniations result in radicu-
lar pain, whereas paramedian or central herniations,
which occur less frequently, will usually produce varying
degrees of myelopathy ranging from an incomplete
Brown—Sequard syndrome to complete paraplegia. Ra-
dicular pain may not be present with paramedian or cen-
tral herniation. The chronic symptom complex usually
begins with a small central or lateral herniation, produc-
ing spinal axis pain. This subsides with time, during
which the true nature of the disorder remains unde-
tected. Progressive fibrosis occurs around the herniated
fragment, often with calcification, resulting in a more
insidious disability. The history of chronic back or ra-
dicular pain, or both, in association with a progressive
myelopathy, will suggest a neoplasm rather than disc
rupture.
The physical findings associated with herniated tho-
racic discs are quite variable. Percussion over the spin-
ous process at the appropriate level will elicit locahzed
discomfort and perhaps accentuate the radicular co1npo—
nent of the pain. In the absence of myelopathy, one will
rarely find disturbances of sensation in the distribution
of the involved thoracic root, because of the considerable
overlap of dermatomes. The signs of myelopathy may be
variable. In severe cases, there will be a distinct sensory
level of the injury, combined with paraparesis. With less
severe involvement, the examination will reveal variable
alterations in function of the coiticospinal and spinotha—
lamic tracts. There may be a sensory level appropriate to
the involved interveitebral disc, either unilaterally or bi-
Disc DISEASE / 431
laterally. In chronic cases associated with mild 1nyelopa—
thy, however, the sensory level may be several segments
below the appropriate intervertebral level. As previously
noted, the finding of a Brown—Sequard syndrome, espe-
cially in the patient with a chronic history of symptoms
associated with disc injury, is not uncommon. Except
with an acute transverse myelopathy, posterior—colu1nn
function is usually intact. Coiticospinal dysfunction will
be heralded by lower—extre1nity paresis and spasticity,
with clonus and Babinski signs present. These may be
unilateral or bilateral depending upon the extent of the
myelopathy.
Diagnosis
While in most cases the physician should suspect the
diagnosis of thoracic disc disease in the acute case, the
history and physical examination in the more chronic
disorder may suggest a neoplasm. Consequently, the
diagnosis in such cases must be confirmed either 1nyelo—
graphically, with CT, or with MRI (61). lohexol is the
contrast medium of choice; few today support the use of
air myelography in thoracic intervertebral disc iuptures.
Venography and discography are of no value, and elec-
tromyography is of little value in the diagnosis.
Because of the normal kyphosis of the thoracic spine
and because of its length, it is necessary to use larger
volumes of iohexol in perfoiming the myelogram than
are necessary for the lumbar or ceiyical area—fro1n 12 to
18 cc may be necessary. It is helpful to place the patient
in the appropriate lateral decubitus position. The typical
finding is an extradural defect posterior to the appro-
priate intervertebral disc space. In the case of a complete
cerebrospinal—ﬂuid block, it may be necessary to intro-
duce the contrast medium directly into the subaraclmoid
space through a lateral puncture of the dura at C1-C2 in
order to determine the upper level of the disorder.
Surgery
In contrast to the situation with a ruptured cervical or
lumbar disc, a thoracic disc rupture in a symptomatic
patient is an indication for surgery without further con-
servative treatment: the small diameter of the thoracic
spinal canal puts the spinal cord in constant jeopardy.
Additional trauma, resulting from minimal anatomical
change, may produce a devastating neurologic deficit.
Although it is safe to manage symptomatically the pa-
tient in whom a thoracic disc iupture is suspected but
who has no signs of myelopathy while the diagnosis is
being electively confirmed, one should proceed expe-
ditiously to surgery when signs of spinal cord co1npres—
sion are noted. The urgency with which surgery is under-
taken will depend upon the degree of myelopathy and
the acuteness of the presentation.

432 / CHAPTER 20
In denning the surgical approach to a ruptured tho-
racic disc, one must keep in mind that the thoracic cord
can tolerate only minimal manipulation, especially
when it is already compromised in the small thoracic
canal, and that the contribution of the spinal radicular
arteries to blood ﬂow in the spinal cord is important. The
standard larninectorny is not suitable for the removal of
a ruptured thoracic disc. With this approach, there is
httle opportunity to explore the disc space without unac-
ceptable retraction on the dura and thus on the spinal
cord. The same holds true for a transdural approach.
Most surgeons today prefer a variation of one of the fol-
lowing approaches: (1) transthoracic, transpleural ap-
proach, in which the disc space is approached from the
right anterior lateral direction (62); (2) costotransversec—
torny, or posterior rachotomy, in which the incision is a
posterior pararnedian rnuscle—splitting incision (63); or
(3) an approach that involves resection of the facet and
pedicle (64). After personal experiences with all three of
these approaches, we prefer the last.
The procedure is performed under general endotra—
cheal anesthesia, with the same preoperative evaluation
as discussed under the management of lumbar and cervi-
cal disc ruptures. The patient is placed in a prone posi-
tion. A rnidline incision is made, and ipsilateral subperi—
osteal dissection of the paravertebral muscles is
undertaken. The dissection is carried laterally beyond
the facets. A hemilarninectorny is done on the vertebra
caudal to the involved disc space. The superior articulat-
ing facet of the inferior vertebra and the inferior articulat-
ing facet of the superior vertebra are removed. Using
appropriate rongeurs and occasionally the air drill, the
pedicle of the inferior vertebra is removed down to the
body of the vertebra. This permits adequate visualiza-
tion of the lateral aspect of the disc space. The nerve root
is identified during the bone resection and protected. Re-
traction of the nerve root cephalad or caudad will reveal
the lateral disc protrusion. An incision is made into this
protrusion, the intervertebral disc space is entered, and
disc material is removed with small angled curettes and
appropriately sized disc rongeurs. More medially located
protruding disc material can be pressed into the disc
space with a number 4 Penﬁeld dissector or an angled
dental instrument and can be removed within the disc
space. Central disc herniations may also be treated in
this fashion.
In the case of a large central herniation, it may be
helpful to perform a bilateral larninectorny. In the un-
usual case in which intervertebral disc material has
eroded through the dura, the dura may be entered lat-
erally with a longitudinal incision and the material re-
moved. Occasionally, for appropriate visualization, sec-
tion ofthe root lateral to the dorsal—root ganglion may be
performed. However, the importance of the radicular ar-
tery rnust be kept in mind. Some have advocated preop-
erative angiography to identify the location of the artery
of Adamkiewicz prior to surgery in the lower thoracic
spine.
Intraoperative monitoring with somatosensory
evoked cortical potentials may be of value. In one of our
patients, prior to sectioning the left Tll spinal root, the
root was temporarily clamped with a vascular clamp.
Within minutes, the patient's evoked potentials ﬂat-
tened. The clarnp was removed, and the evoked poten-
tials returned to normal over approximately 60 minutes.
The root was not sectioned, and postoperatively, the pa-
tient had no deﬁcit. The usefulness of this monitoring
technique, however, must be further verified before it
can be fully accepted.
Following completion of the disc removal, the wound
is thoroughly irrigated with saline and the dura is re-
paired, if previously opened. The wound, including the
skin, is closed in layers. The patient is permitted arnbula—
tion as tolerated. Postoperatively, neurologic recovery
will depend upon the degree and duration of the deficits
present prior to surgery. Because of the relatively small
number of cases of thoracic disc disease, the long—term
frequency of recurrence of the disease in such cases is
unknown.
DISCITIS
Inﬂammation of the disc, or discitis, is seen in three
clinical situations: in association with vertebral osteo-
rnyelitis (65); following intervertebral disc surgery (66),
both septic and aseptic; and spontaneously, usually in
children (67).
Vertebral Osteomyelitis
Pyogenic vertebral osteitis can be caused by any patho-
genic organism; in the majority of cases, staphylococcal
infections are the etiology (68). Although rare instances
of direct infectious extension do occur as the cause of
such osteitis, it seems that most ofthese lesions are rneta—
static. The vascular pathway may be arterial in some
cases but, because of the predominance of infections as-
sociated with intra—abdorninal and intrapelvic pathol-
ogy, Batson's venous plexus (69) has been incrirninated
by most authorities as the major route of infection. In
the case of an epidural—space infection or an infection in
the vertebral body, the intervertebral disc space becomes
infected by direct extension. The relatively avascular na-
ture of the disc space in adults makes direct extension,
rather than metastasis, the most plausible explanation
for infection in this population.
The patient will complain of back pain, insidious in
onset and progressing to become quite severe. Exarnina—

tion reveals an exquisite local tenderness to percussion,
much greater than that seen with a disc herniation or
spinal neoplasm. The patient may have a low—grade
fever. The erythrocyte sedimentation rate (ESR) is rnark—
edly elevated, often over 100 mm/hour. The peripheral
blood leukocyte count may be quite high, but is usually
only moderately elevated. Radiographs will show evi-
dence of destruction of one or two vertebral bodies, with
areas of rarefaction and body collapse. The interverte-
bral disc space will be narrowed, with indistinct cortical
surfaces of the vertebral body adjacent to the disc space.
New bone formation appears early in acute pyogenic os-
teitis, in contrast to the prolonged rarefaction seen in
tuberculosis. With appropriate antibiotic therapy, sclero-
sis will be seen in two months, and evidence of fusion
across the intervertebral disc space will be seen by three
months.
Procedures for confirmation of the suspected diagno-
sis will depend upon the clinical state of the patient. If
the patient has no neurologic deficit, a needle biopsy
with aspiration of the involved vertebral body or inter-
vertebral disc space is appropriate. If, however, the pa-
tient has a neurologic deficit, and especially if the tho-
racic vertebrae are involved, myelography should be
used to reveal evidence of epidural involvement and pos-
sible spinal cord compression. If this is noted, a standard
decompressive laminectomy is undertaken, with rnate—
rial being taken for pathologic examination (70).
The treatment of vertebral osteomyelitis will be dic-
tated by the causative organism, the extent of neurologic
involvement, and the degree of spinal instability. Prior to
obtaining positive cultures, a cephalosporin or a serni—
synthetic penicillin with antistaphylococcal activity and
an aminoglycoside for grarn—negative coverage, can be
given, although this may suppress growth from the
biopsy. If the discitis has been associated with an epidu-
ral infection requiring larninectorny, the wound may be
left opened and irrigated daily with an appropriate antibi-
otic solution, such as one containing 100,000 units of
polymixicin—B, 50,000 units of bacitracin, and l g/liter
of neomycin in saline. After two to three weeks, when
the depths of the wound are covered with good granula-
tion tissue and cultures are negative, the irrigating cath-
eters and sponge packs may be discontinued, and a sec-
ondary closure with wire can be done. If vertebral
instability is suspected, it is best to maintain the patient
on bed rest until radiographic evidence of fusion is seen.
The patient may then ambulate with the aid of an appro-
priate brace.
Tuberculous vertebral osteomyelitis is a virtually non-
existent clinical entity in the United States, except in
refugee populations. It should be suspected in any pa-
tient with evidence of vertebral osteomyelitis and in
whose natural habitat tuberculosis is still a clinical prob-
lem (71).
Disc DISEASE / 433
Postoperative Discitis
Bacterial (Septic) Discitis
It is not uncommon, following routine surgery for disc
disease, for a patient to run for one to two days a low-
grade fever that is self—lirniting and requires only aspirin
for symptomatic relief. However, the patient who has
developed a disc—space infection will, between one and
two weeks postoperatively, begin to complain of increas-
ingly severe back pain. This may be associated with
marked temperature elevation, with temperatures of
l04°F not uncommon. These findings are associated
with a markedly elevated ESR and peripheral leukocyto—
sis. The pain is unrelieved by bed rest and exacerbated by
ambulation. Organisms may be recovered from the in-
tervertebral disc space by blood culture or percutaneous
aspiration. Initial radiographs in such cases are unre-
markable. With time, however, the changes typically as-
sociated with discitis will be seen, with further narrowing
of the disc space and the development of an irregular
indistinctness to the cortical margins of the adjacent ver-
tebral bodies. With healing, sclerosis and fusion will
occur.
External evidence of infection with wound drainage
will occur in approximately 20 percent of patients with
septic discitis (72). In these instances, appropriate surgi-
cal drainage is indicated. Proper antibiotic therapy
should be instituted, and the patient should be kept on
bed rest until asymptomatic. In the absence of osteornye—
litis, the spine is not unstable and the patient will not
need external orthotic support during ambulation.
Aseptic Discitis
In some patients with symptoms similar to but milder
than those of septic discitis, there will be evidence of
infection but without organisms being obtained from ei-
ther the blood or disc space. The onset of this condition
may be weeks or months after surgery, usually after the
patient has resumed essentially normal activity. The pa-
tient will complain of increasingly severe back pain
made worse by activity. Progressive narrowing of the
disc space will occur, along with the development of in-
distinct cortical margins. This entity has loosely been
termed aseptic discitis, suggesting the lack of an in-
fectious organism as its cause and the relatively benign
nature of this disorder. It is probably due to aseptic ne-
crosis of portions of the vertebral bodies adjacent to the
disc space, perhaps as the result of excessive curettage
within the disc space at the time of surgery. The disorder
may progress over a period of several months to ﬁbrous
ankylosis or bony fusion. The patient should be inan-
aged syrnptornatically, with physical activity being lirn—

434 / CHAPTER 20
ited to that which the patient can tolerate. Some patients
will benefit from the relative immobility imparted by an
external brace or corset. Differentiation between aseptic
and infectious discitis may be difficult, and some
patients with the clinical symptoms of discitis without
positive cultures may nevertheless be treated with a pro-
longed course of intravenous broad—spectrum antibi-
otics.
Discitis in Children
Primary infection of the intervertebral disc space in
children is uncommon, although it does occur with
greater frequency than in nonsurgically—treated adults.
Presumably this is due to the increased vascularity in the
disc space in childhood. The clinical presentation is very
similar to that in the postoperative adult, without exter-
nal evidence of infection. Fever, low back pain, the re-
fusal to stand or walk, and general malaise and irritabil-
ity constitute the common clinical findings. There is
usually spasm of the back muscles, but no abnormal neu-
rologic findings. Cultures of the blood or disc—space aspi-
rate generally yield Staphylococcus, and usually S. au-
reus. An elevated erythrocyte sedimentation rate is
noted. Radiographs reveal narrowing of the appropriate
intervertebral disc space, with dernineralization of the
adjacent vertebral body margins.
There is no indication for radical surgical treatment of
this condition. The appropriate antibiotics should be
given. The child is kept on bed rest until arnbulation is
comfortable. This may take three to five weeks. With
arnbulation, external bracing is usually not necessary.
Recovery of normal activity without residual neurologic
or skeletal sequelae is the rule.
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in elective surgery. JAMA

CHAPTER 21
Spinal Stenosis
Clark Watts and Kent Grewe_
Pathology, 437
Cervical Disease, 438
General Considerations, 438
Presentation, 438
Diagnosis and Management, 439
Surgery, 440
Lulnbar Disease, 441
Spinal stenosis is a generic term denning a narrowed spi-
nal canal that results in a variety of neurologic syn-
dromes because of localized compression of the spinal
cord or spinal roots. The stenosis may be congenital, as
in acrondroplasia; developmental, as in degeneration
(spondylosis); or iatrogenically acquired following spine
surgery.
In general, the neurologic syndromes associated with
cervical and lumbar stenosis resemble those of interver-
tebral disc disease with herniation. However, there are
specific factors related to the pathology, diagnosis, and
management of spinal stenosis that distinguish this con-
dition from intervertebral disc disease. Primary thoracic
spondylosis (i.e., that which is not due to fracture or con-
genital or developmental kyphoscoliosis) is quite rare. Its
diagnosis and management are basically similar to those
of thoracic disc disease.
Plain spine x—rays, myelography possibly followed by
computed tomography (CT), and magnetic resonance
imaging (MRI) are currently the diagnostic procedures
of choice for spinal stenosis and its associated neurologic
syndromes. The goal of surgical intervention is the de-
compression of the neural elements with maintenance of
spinal stability.
C. Watts and K. Grewe: Division of Neurosurgery, Univer-
sity of Missouri School of Medicine, Columbia, Missouri
65212
437
Principles 0ﬂVeur0surgery,
edited by Robert G. Grossman, Rosenber © 1991.
Published by Raven Press, Ltd., New Yor .
General Considerations, 441
Presentation, 441
Management, 442
Diagnostic Procedures, 442
Surgery, 443
Results of Surgery, 444
References, 444
PATHOLOGY
Achondroplasia, a rare disease of endochondral bone
formation, is inherited as an autosomal dominant trait.
It is manifested in childhood by dwarfism and a variety
of skeletal abnormalities. The spinal abnormalities in
achrondroplasia include extremes of kyphosis and sco-
liosis, resulting in constriction of both the lateral and
sagittal diameters of the spinal canal and in spinal cord
compression (1). This is of particular concern in the
upper cervical spine and in the region of the foramen
magnum.
Developmental changes occur after birth and are pri-
marily due to spine and disc degeneration, resulting
from the repeated minor trauma of daily living or from
instances of major trauma. The "normal" configuration
of the patient's vertebrae may contribute to the symp-
tomatology that results from the degenerative changes in
the disease. Examples of this are seen in the horizontally
and vertically oriented lumbar laminae. The cephalad
borders of the horizontal laminae may, with developing
lordosis, compress the spinal cord in its posterior aspect
(2), while the vertically oriented laminae tend to have
shortened pedicles and narrowed lateral diameters. With
hypertrophy of the facet joints, compression ofthe cauda
equina may become significant (3,4).
Spondylotic changes are more apparent in the cervical
spine at C5-C6 and C6-C7 and in the lumbar area from
L3 caudad than in other regions of the spine. Such
changes, unusual in the thoracic area, are thought to be

438 / CHAPTER 21
the result of excessive stress at these locations, resulting
in annular and ligamentous incompetency leading to in-
stability. Ligamentous, uncovertebral, and facet joint
hypertrophy and osteophyte formation occur. It is sus-
pected that, in the cervical region, the C5-C6 and C6-C7
interspaces are subjected to greater stress than the other
disc spaces because the incidence of ruptured disc is
greater at these two interspaces (5). The same can be said
0 for the lower lumbar interspaces (6). According to this
view, the relative fixation of the thoracic spine (because
of the ribs) explains the rarity of significant primary
spondylotic changes in the thoracic spine.
With excessive stress and the consequently accelerated
disc degeneration, the annular fibers of the disc and the
intervertebral ligaments lose resilience and elasticity.
This is especially true of the interlaminar ligaments, and
the ligaments of the uncovertebral and facet joints.
These changes result in relative instability at the inter-
vertebral disc space, which contributes to a loss of resil-
ience and elasticity of the posterior and anterior longitu-
dinal ligaments. Since the primary annular and
ligamentory substance that imparts strength and elastic-
ity to these structures is a collagen (7), it is reasonable to
assume that the "wear and tear" phenomonen results
from a change in the structure of this collagen. Indeed,
with age or prolonged trauma, the proportions of protein
polysaccharides and noncollagenous proteins within the
ligaments and annulus change, increasing in keratosul—
fate and beta protein. However, the true relationship be-
tween these changes and the deterioration in the stabiliz-
ing properties of the ligaments and the annulus remains
unknown.
The net result of these changes is spondylosis. There
occurs a separation of the peripheral fibers of the annu-
lus fibrosis and of Sharpey's fibers from the edges of the
vertebral body. The weakened annulus leads to instabil-
ity of the intervertebral motion segment, resulting in
reactive bone formation at certain sites and in ligamen-
tous hypertrophy (8). The sites most notable for this os-
teophytic bone formation are anterior, at the interface of
the disc, anterior longitudinal ligament, and vertebral
body; posterior, at the interface between the annulus,
posterior longitudinal h gament, and vertebral body; pos-
terolateral, at the point where the posterior longitudinal
ligament is thinnest and thus gives less support to the
stressed annulus; and at the facet processes that, as part
of the facet joint, are subject to increased stress because
of the unstable intervertebral motion segment. *
Increasing spondylosis of the posterior aspect of the
vertebral bodies and intervertebral disc spaces leads to
anterior encroachment on the spinal canal. Hypertrophy
of the ligamentum flavum leads to posterior encroach-
ment on the canal, especially with the spine in extension.
Increasing mobility of the intervertebral segment—the
disc space and the facet joints—leads to hypertrophy of
the facet and uncovertebral joints with posterolateral
and anterolateral encroachment on the canal. Because of
its rigidity, the thoracic spine is generally unaffected by
clinical spondylosis except following isolated episodes of
specific trauma (e.g., fracture), or in the case of congeni-
tal kyphoscoliosis.
The encroachment on the spinal canal that results
from the foregoing changes leads to cervical spondylotic
myelopathy (CSM) in the cervical area and cauda equina
compression in the lumbar area. Facet hypertrophy and
uncovertebral joint hypertrophy may result in the en-
trapment of nerve roots due to foraminal compromise
(lateral recess stenosis). Additionally, pain is produced
by the excessive motion allowed in the intervertebral seg-
ment, which stimulates nerve fibers in the ligaments,
facet joints, and annulus (9-11).
Spinal stenosis may develop as a result of previous
surgery, especially on the lumbar spine (4,12). Epidural
fibrosis and reactive bone formation may follow laminec—
tomy. A common cause of such stenosis is an excessive
deposition of bone around a spinal fusion. This may oc-
cur in any area of the spine where the fusion is done,
from a posterior or an anterior approach. The develop-
ing signs and symptoms are similar to those of spondy-
losis.
CERVICAL DISEASE
General Considerations
In patients over the age of 50, most of the symptoms
associated with cervical spine disease are due to spondy-
losis; disc rupture in the absence ofspondylosis or signifi-
cant trauma is relatively unusual. In the sagittal plane,
the cervical canal is roughly funnel—shaped and reaches is
narrowest diameter between C4 and C7. The maximal
stresses and secondary spondylotic changes of the cervi-
cal spine occur in this area, and the cord blood supply is
felt to be most susceptible to ischemia owing to the lack
of collateral vessels and maximal atherosclerotic changes
here. Therefore, symptomatic CSM or root entrapment
most commonly occurs between C4 and C7. However,
even here the normal ranges of canal diameters are felt to
tolerate considerable spondylotic encroachment without
threatening myelopathic symptoms. Many feel that it is
only the congenitally narrowed canal that endangers the
spinal cord (13).
Presentation
The syndromes associated with cervical spondylosis
are similar to those associated with chronic cervical disc
disease and are related to localized cord or nerve root
compression with secondary inflammatory, demyelinat—
ing, or axonal changes. In patients with cervical stenosis,
symptoms most commonly consist of an episode of neu-

rologic deterioration followed by a period of clinical
plateau. Patients may develop rapid deterioration at any
time and, unfortunately, no prognostic predictors are
currently known (14-16). The symptoms include suboc-
cipital neck, shoulder, and arm pain; various degrees of
lower motor—neuron deficits; and myelopathy. Although
cervical disc disease is rare above C4-C5, spondylosis
does occur at C2-C3 and C3-C4. Laterally located spurs
may be the source of pain stemming from the C2 to C4
dermatomes, expressed as posterior cervical and suboc-
cipital pain and headache. It is clear that most cases of
what was once diagnosed as "occipital neuralgia," a
symptom complex characterized especially by lancinat-
ing posterior head pain, are due to cervical spondylo-
sis (17).
As in surgical disc disease, most of the symptoms of
spondylosis are due to the involvement ofthe C5-C6 and
C6-C7 interspaces. The patient will complain of increas-
ingly severe neck, shoulder, scapula, and arm pain. The
pain and paresthesias will be in the distribution of the
appropriate root dermatome. The painful symptoms are
more noticeable than in cervical disc rupture, in which
weakness is prominent. The pain is of particular inten-
sity with extension or ipsilateral flexion of the neck
(Spurling's maneuver) but is often relieved by anterior or
contralateral flexion. The shoulder abduction test, neck
compression, and the axial manual traction tests have
been mentioned as reliable clinical tests (18-20).
The sudden onset of symptoms in cervical spondylosis
is explained as follows. Both antero- and posterolateral
spur formation and hypertrophy of the uncovertebral
joints and facets tend to narrow the spinal foramen. Nor-
mally, hyperextension and ipsilateral flexion also narrow
the foramen. If the foramen already is compromised by a
significant spondylosis, sudden excessive extension or ip-
silateral flexion may result in contusion of the nerve
root. This is followed by edema of the root and pen"-
neural tissue within the foramen, leading to further com-
pression and compromise of the nerve root and the pro-
duction of an ongoing radiculopathy. That most acute
radicular symptoms are self-limiting with rest, and that
one does not always find an extruded disc fragment at
surgery in these patients lend credence to this explana-
tion. Patients with cervical stenosis are more susceptible
to cervical spinal cord injury following trauma to the
head and neck than are those with stenosis in other re-
gions of the spine. This is particularly true with exten-
sion-type injuries. The most common neurologic injury
sustained in the absence of spine malalignment is that
which occurs in the central cord syndrome.
Compression of the vertebral artery by lateral osteo-
phytes may also occur (21) and may produce symptoms
of vertebral basilar insufficiency, characteristically upon
lateral rotation or extension of the neck. An angiogram
with the chin toward the opposite side will reveal in-
creased stenosis or occlusion of the involved artery.
SPINAL STENOSIS / 439
While a hemodynamic alteration is usually postulated as
the cause of the symptoms, Verbiest reported improve-
ment in a patient who had bilateral vertebral artery oc-
clusion (17), suggesting that the symptoms may have an
embolic origin.
The differential diagnosis of cervical disc disease (see
Chapter 20) is appropriate to cervical spondylosis. How-
ever, the patient with spondylosis usually has a more
protracted course with an insidious onset, suggesting the
possibility of an intraspinal neoplasm and syringomye-
lia. Of particular concern here is a foramen magnum
tumor (22). Compression of the second cervical nerve
root by this tumor may cause occipital pain along with
an admixture of upper and lower motor—neuron findings
in the extremities.
Diagnosis and Management
Because of the myriad combinations of neurologic
signs and symptoms that cervical spine disease can pro-
duce, the patience and the diagnostic capability of the
physician may be taxed considerably (23). Of impor-
tance in the histories of patients with cervical spondylo-
tic disease is that pain, especially with movement of the
neck, is usually the most outstanding feature. However,
various degrees of disability, including advanced myelop-
athy with bladder dysfunction, can also be seen. The ex-
tent of spondylosis and disc-space narrowing will be ap-
parent on the plain films, with oblique views
demonstrating osteophytes in the foramina. Varying
portions of these osteophytes may be in a state of precal-
ciﬁed ﬁbrosis, and therefore the full extent of the com-
pressive defect may not be apparent. The most restrictive
anteroposterior (AP) diameter usually occurs between
the hypertrophic growth from the inferior dorsal rim of a
vertebral body and the superior lip of the neural arch of
the next inferior vertebra. Thirteen to fourteen milli-
meters AP canal diameter has been established as an ap-
proximate critical dimension on lateral cervical spine
films (13,24,25). However, the accuracy is dependent on
radiographic technique, including changes in the focus-
to-film or object-to-film distances, and different body
types (26). Pavlov and Torg have shown a critical ratio of
0.82 (sagittal diameter of the spinal canal/sagittal diame-
ter of vertebral body), which is independent of magnifi-
cation, technique factors, and variation in body types
and is therefore more reliable (27).
Lordosis in the cervical spine may create a false appear-
ance of spinal stenosis on CT. Therefore, measurement
ofthe sagittal dimensions ofthe cervical spine on conven-
tional lateral radiographs is felt to be more reliable than
CT scanning (27,28). Lateral flexion/extension plain
films are frequently taken to evaluate spinal mobility
and stability. Myelography is still preferred, as it depicts
the net effect of stenosis on the subarachnoid space and

440 / CHAPTER 21
the ﬂow of dye can be observed under fluoroscopy to
give some further insight into the degree of stenosis and
obstruction (29,30). Postmyelography CT axial cuts de-
pict the specifics of bony and ligamentous anatomy,
which can be helpful for evaluating the presence and
extent of ossiﬁcation of the posterior longitudinal liga-
ment, and ligamentous, facet, or uncovertebral joint hy-
pertrophy (31). This is helpful in planning operative ap-
proaches, expectations, and risks. MRI axial cuts have
been found to be less helpful, but sagittal T2—weighted
views provide a myelographic effect and insight into the
degree of hydration and degeneration inherent to the
disc. MRI is also very helpful in evaluating both intrinsic
and extrinsic spinal cord changes, including atrophy,
cystic degeneration, and tumors (32). The "best"
method for imaging the spondylotic spine remains con-
troversial and somewhat dependent on the pathology
and on the user (33-36). In general, for imaging the
spondylotic spine, we prefer plain films initially, then
myelography, possibly followed by CT scanning.
Most patients without myelopathy will respond satis-
factorily to conservative management. This includes de-
creased physical activity, bed rest if necessaiy, the use of
nonsteroidal antiinflammatory drugs, analgesics, and
muscle relaxants, and gentle massage with the applica-
tion of heat or ultrasound. It is important that both heat
and ultrasound be used intermittently and brieﬂy; no
application of these therapeutic modalities should last
more than 20 minutes. Both increase the temperature in
the muscles, resulting in additional muscle irritability
leading to further spasm and more pain.
Cervical traction may be helpful. It is best applied with
an occipital—mandibular halter. The angle of pull should
be such that the head and neck reside in a slightly flexed
attitude; this will tend to open the foramina and decom-
press the nerve roots. It is important that the traction be
applied intermittently. If confined to bed, patients
should be permitted 15 to 30 minutes of traction—free
time every two hours. Traction should not be applied
through the night; instead, patients should be instructed
to sleep on a firm pillow, maintaining slight flexion of
the head and neck.
As the symptoms decrease, patients should be encour-
aged to increase their physical activity. A single period of
symptomotology does not warrant a significant change
in a patient's life—style, but repeated bouts require that
the physician and the patient work together to analyze
the patient's life—style and work habits, so as to help the
patient understand which situations tend to aggravate
the condition. The patient should be helped to fully un-
derstand the pathophysiology of the disease.
Exercise involving the neck, shoulders, and upper ex-
tremities should be encouraged. Significant, physically
stressful exercise—an extreme example being weight lift-
ing—should be avoided. Suitable exercises include hik-
ing and swimming. The patient should be instructed in
the at—home use of traction, in either the reclining or
sitting position, as this will permit early self—treatment
and usually prevent periods of prolonged disability. The
patient should not be encouraged to wear a cervical col-
lar. A soft collar is of little value, although a firm collar
may be used briefly during those symptomatic periods
when the patient absolutely must be up and about. This
will reduce neck movement and support the weight of
the head. However, as with any form of immobilization,
the prolonged use of a collar will result in additional
weakness of the cervical musculature and loss of support
to the cervical spine, eventually leading to increased
symptomatology.
Surgery
The main indication for surgery in cervical spine dis-
ease is cervical spondylotic myelopathy with a progres-
sive neurologic deficit, or persistent radiculopathy resis-
tant to conservative therapy—each associated with
corresponding radiographic evidence supporting the
clinical impressions. A lesser indication for surgery is
persistent radicular pain without significant weakness.
Neck pain without myelopathy or radicular symptoms is
not an indication for surgery, although exceptions to this
rule may be made when there is x—ray evidence of focal
disease, such as the narrowing of a single disc space, angu-
lar kyphosis, or slight subluxation, especially if there is a
past history of signiﬁcant trauma to the intervertebral
disc segment.
Surgeiy for cervical spondylosis should be preceded by
the appropriate imaging studies with the examination
carried up through the foramen magnum. Patient selec-
tion is important. It can be very difficult at times to sepa-
rate outpatients with amyotrophic lateral sclerosis, mo-
tor neuron disease, or demyelinating disease, as well as
those patients depressed or motivated by primary and
secondary gain. Nonoperative care should be considered
in patients with advanced neurologic deficits and fixed
lesions, fluxuating deficits, and central cord injuries and
those who are a poor operative risk (32).
Traditionally, posterior decompression through a bi-
lateral laminectomy has been the procedure of choice for
multilevel disease, especially myelopathy (32). Posteiior
decompression can be performed in either the sitting or
prone position. We feel that the risk ofair emboli in the
sitting position for cervical procedures (away from the
skull) is very low and that this position allows for im-
proved visibility—especially when performing forami-
notomies. One to two levels should be decompressed
above and below the area of maximal stenosis. All efforts
should be made to preserve the C2 vertebra and its mus-
cle attachments. Posterior decompression is contraindi-

cated if a kyphotic deformity or any evidence of anterior
instability is already present (32,33).
When performing bilateral laminectornies for multi-
level disease, one should be careful to avoid excessive
resection of the facet joints. Both the anterior and poste-
rior longitudinal ligaments are weakened during the
spondylotic process, and with removal of the interspin—
ous ligaments, the stability of the spine depends upon the
competency of the facet joints and their ligaments. Ex-
cessive disturbance of these articular complexes carries
the risk of potential instability in the form of cervical
kyphosis, swan—neck deformity, or multiple—level sub-
luxation (37). Only the medial portions of the facet need
be resected to adequately decompress the spinal cord.
Foraminotomy should be performed only of those fora-
mina in which definable radicular symptoms have been
traced.
Variations of the posterior "open—door laminaplasty"
were introduced by Krita in 1968 and by Hattori in
1972, and revised by Hirabayashi in 1977 (39-42). In
general, these authors advocate an "expansive" lamino—
plasty, with unilateral hingeing of the lamina over the
longitudinal distance of the procedure. The intraspinal
ligaments are preserved. The advantages claimed in-
clude a decreased risk of postoperative neurological defi-
cit or changes due to kyphosis or instability. Disadvan-
tages include technical difficulties, excessive loss of
cervical range of motion, and inadequate decompression
on the hinged side.
Disease of one or two adjacent spaces may be handled
by anterior discectomy, with or without fusion (42-48).
Cloward and others feel multiple levels can also be man-
aged with variations of anterior decompression and fu-
sion, especially with multilevel ossifrcation of the poste-
rior longitudinal ligament (49-51). The decision to
perform anterior discectomy alone or with fusion re-
mains controversial. The increased risk of degenerative
change at the levels above and below the fused segment,
pseudoarthrosis, graft dislodgement, iliac crest prob-
lems, and loss of mobility are reasons claimed for avoid-
ing fusion (37). On the other hand, many feel that postop-
erative pain, disc—space settling, spinal angulation, and
degenerative changes are increased when discectomy
without fusion is performed (38). These changes may
lead to the necessity of a secondary fusion. For disease
primarily localized anteriorly and limited to one or two
levels, we prefer anterior decompression with Cloward
or Smith—Robinson fusions.
Postoperatively, once the patient has recovered from
the surgical procedure, continued management is advo-
cated along the conservative lines previously outlined.
The patient must be followed closely on a long—term ba-
sis. If subluxation becomes apparent in a patient who
underwent an anterior procedure without fusion, ante-
rior fusion may be necessary. Patients who do not have
SPINAL STENOSIS / 441
anterior fusion after anterior discectomy may need ex-
ternal support during the three to four months in which
bony fusion occurs. The support may be a simple firm
collar, a Guilford or SOMI—type brace, or a halo vest,
depending on the degree and location of instability.
Pathology of cervical spondylotic myelopathy shows a
fairly uniform pattern, demonstrating degeneration of
the posterior and lateral white matter tracts with relative
sparing of the anterior columns (52). Therefore, somato—
sensory—evoked potentials (SSEPs), which primarily re-
ﬂect posterior column function, can be used to follow
patients with cervical spondylotic myelopathy. In opera-
tive cases, particularly those with tight stenosis, intraop—
erative SSEP monitoring may be considered. Motor-
evoked potentials (MEPs) with pulsed magnetic
stimulation show promise for future intraoperative ante-
rior cord monitoring (53).
Anterior and lateral approaches to surgical decom-
pression of a vertebral artery compromised by cervical
osteophytes have been described (54,55). If the symp-
toms of the compromise are determined to be embolic in
origin and the involved artery is nondominant, proximal
ligation of the artery is the simplest surgical procedure.
LUMBAR DISEASE
General Considerations
Congenital narrowing of the lumbar spinal canal, un-
complicated except by kyphosis and scoliosis, may be
the cause of significant symptomatology in the patient
with achondroplasia (56). The diagnosis and manage-
ment of this constriction is similar to that in cases of
congenital canal narrowing complicated by spondylosis.
Lumbar stenosis secondary to spondylosis may, as
with cervical spondylosis, present in many ways. A single
radicular—symptom complex may be seen, which, as in
lumbar disc disease, can be acute or chronic. Alterna-
tively, the patient may note a chronic bilateral multilevel
disability. A relatively asymptomatic patient with exten-
sive spondylosis may become symptomatic as a result of
disc rupture. More commonly, a patient will present
with a combination of syndromes. Principally seen are
syndromes of cauda equina compression, a subclass of
which is cauda equina claudication, and of lateral root
compression at one or more levels, a variant of which is
lateral recess syndrome. Spinal stenosis is also com-
monly seen as a result of degenerative, congenital, or
iatrogenic spondylolithesis or scoliosis, and following a
previous discectomy, laminectomy, or fusion (4,57).
Presentation
The typical patient with symptomatic lumbar stenosis
is beyond the fifth decade of life and has noted progres-

442 / CHAPTER 21
sively severe hack pain, insidious in onset (58). Asso-
ciated with the back pain are nondermatomal, painful
paresthesias in both lower extremities. Initially, the pain
is worse with physical activity, but it may ultimately be-
come continuous. Urinary hesitancy or incontinence
may be noted. Fecal incontinence and priapism have
also been reported (59,60). Generalized lower extremity
weakness is ultimately perceived by the patient, although
the sensory symptoms usually predominate. Other
vague symptoms of muscle cramping and coldness of the
extremities may be reported.
Examination may reveal bilateral lower extremity
weakness and atrophy involving several muscle groups.
Patchy, multidermatomal hypesthesia may be noted, as
may diminished or absent quadriceps and Achilles‘ deep
tendon reﬂexes. The results of sciatic stretch tests are
usually normal.
As noted above, an important variant of the basic syn-
dromes of lumbar stenosis—spondylosis is intermittent
cauda equina claudication (61,62). The symptoms of
this are produced consistently by walking, standing, or
sitting with the lower back in the lordotic position. The
symptoms characteristically appear within seconds or
minutes of continued activity. The pain is not sciaticlike
or dermatomal, but instead is described as a generalized,
usually bilateral lower—extremity cramping or burning,
with profound numbness or weakness. The pain is re-
lieved by rest. Patients with this condition often note
that they can increase the length of their activity toler-
ance by bending forward. Examination of the patient
during an asymptomatic interval may give normal re-
sults, although sensory deficits, weakness, and dimin-
ished reﬂexes may be noted if the patient is examined
following the onset of symptoms. In fact, it is the finding
of an increased neurologic deficit following the onset of
symptoms that helps distinguish the cauda equina clau-
dication syndrome from the intermittent ischemic mus-
cle claudication of Charcot (62).
The etiology of the symptoms in intermittent cauda
equina claudication is unclear. It is known that with ex-
ercise the conducting peripheral nervous tissue experi-
ences an increased oxygen demand and thus an in-
creased arterial blood requirement (63,64). Indeed,
widely dilated vessels of the spinal nerve roots have been
noted in exercised animals (65). It has accordingly been
suggested that in spinal stenosis vasodilitation may cause
additional nerve root compression or, conversely, that
the stenosis, through vascular compression, may prevent
the increased delivery of blood required by active periph-
eral nervous tissue, and that when combined with periph-
eral arteriosclerosis this may lead to neural ischemia dur-
ing activity. Others suggest that the syndrome might be
brought on by extradural venous congestion leading to
additional nerve—root compromise. Pressures within the
spinous processes ofthe lower lumbar vertebrae triple in
movement from the recumbent to the upright position;
the pressures are transmitted to the epidural veins (66).
In the patient with spinal stenosis, these changes are espe-
cially notable in the L3 spinous process.
Another variant oflumbar spinal stenosis is the lateral
recess syndrome (67). Pathologically, this condition is
marked by facet hypertrophy with narrowing of the lat-
eral recess of the spinal canal. This results in localized
nerve—root compression at the foramen and in compres-
sion of the lateral aspect of the descending cauda equina,
resulting in symptoms of lower—root involvement. The
hypertrophy usually occurs at multiple facets, and a vari-
ety of bilateral lower—extremity signs and symptoms of
nerve—root dysfunction are therefore noted. The symp-
toms may be unilateral and dermatomal with a localized
lateral recess stenosis.
Management
Initially, the patient with lumbar disease should be
managed symptomatically with rest, nonsteroidal anti-
inflammatory drugs, local heat, muscle relaxants, and
analgesics, with appropriate observation for any progres-
sive neurological deﬁcits. Platelet—inhibiting and blood
viscosity medications such as Trental® have been tried
with mixed success. However, as opposed to lumbar disc
disease, in which the majority of patients respond satis-
factorily to symptomatic management, patients with
symptomatic spinal stenosis and spondylosis usually ob-
tain only temporary relief with such management. This
is because the pathologic process in the latter condition
primarily involves bony compression, which will not re-
solve with rest. In managing the disease, consideration
should be given to the patient's age and medical status,
since most patients with the disease are elderly. These
factors, combined with an understanding of the patient's
work requirements and level of activity, will help in the
development of a management plan. A patient who is
symptomatic with three miles of walking may respond to
a reduction in the degree and intensity of physical activ-
ity. A patient whose limitations are dictated primarily by
peripheral cardiovascular disease and not spinal stenosis
should be managed conservatively. The patient whose
physical activity will be sharply reduced by the move
from full employment to retirement may require little
speciﬁc treatment other than advice about proper exer-
cise and related health matters. However, most patients
who have disabling pain with limited physical activity or
who have progressive neurologic deﬁcits with or without
pain will require surgical management for optimal relief.
Diagnostic Procedures
In lumbar stenosis secondary to spondylosis, radio-
graphs of the lumbar spine reveal multilevel spondylotic

changes with osteophytes, facet hypertrophy, and disc-
space narrowing. Interpedicular and sagittal measure-
ments of the canal on plain films may be helpful in denn—
ing the stenosis, but the full extent of the latter may not
be appreciated, since the noncalcified fibrotic changes
that occur at the advancing edges of the spondylotic and
hypertrophic processes will not be apparent (29,68,69).
Lateral flexion and extension lumbar spine films are of-
ten obtained to evaluate spinal mobility and stability.
Myelography utilizing iohexol has minimal morbidity
and demonstrates the net effect of stenosis on the sub-
arachnoid space. In addition, the pattern of contrast
movement within the spinal canal can be observed
under fluoroscopy (29,30). Changes associated with flex-
ion and extension and weight bearing can also be ob-
served (70). Occasionally, the injection of contrast media
may be difficult because crowding of the nerve roots and
obliteration of the subaraclmoid space can make place-
ment of the needle and removal of cerebrospinal fluid
(CSF) difficult. CSF protein may be elevated, although it
rarely exceeds 150 mg/deciliter.
Extradural myelographic defects are found at each in-
volved intervertebral disc space. On the lateral view, en-
croachment on the contrast column by the hypertro-
phied laminae and interlaminar ligaments posteriorly
and by the osteophytes anteriorly imparts a "wash-
board" appearance. The combination of the hypertro-
phied facets and the osteophytes produces, on the ante-
rior view, multiple waistlike defects at the intervertebral
spaces. While this may be visually significant with spon-
dylosis alone, it is markedly exaggerated in the presence
of spinal stenosis. A complete CSF block is not uncom-
mon, especially at L3—L4.
Delayed postmyelography CT scanning delineates the
specifics of bony and soft tissue anatomy, including the
lateral recess, canal dimensions, osteophytes, ligamen-
tous hypertrophy, and the intervertebral disc, and has
been shown to greatly increase accurate diagnosis of her-
niated discs in the setting of stenosis (34,71). It is also
helpful for anatomical evaluation in patients with a
previous history of lumbar surgery and secondary epidu-
ral scarring. Perineural cysts, conjoined nerve roots,
edematous nerves, and other soft tissue anatomical vari-
ants are well depicted with myelography and follow—up
CT scanning (34). Sagittal T2—weighted MRI is helpful in
evaluating the degree of hydration and degeneration of
the intervertebral disc spaces. This becomes important if
one is contemplating combined decompression and fu-
sion, as many believe fusion should bridge and not termi-
nate at the degenerative interspace. T2—weighted MR
images give a myelographiclike effect. Resolution of sag-
ittal MRI is better than reformatting axial CT cuts into
sagittal reconstructions (34). However, with myelogra-
phy followed by CT scanning, reformatting is not neces-
sary. MRI is more examiner—dependent, but many feel
that, in the proper hands, it is diagnostically superior
SPINAL STENOSIS / 443
(34,35). The "best" method for imaging the spine—in
terms of cost, radiation, time, invasiveness, technical
skills, and anatomical detail—remains controversial. In
general, we prefer myelography with follow—up CT scan-
ning for imaging the spondylotic stenotic spine, and
MRI for evaluating the cord, cauda equina, disc degener-
ation, and other vertebral pathology.
Surgery
Decompressive surgery is indicated for lumbar steno-
sis when nonsurgical management fails (72-74). This fail-
ure is characterized by nonresolving disabling pain or
neurologic deficit. The patient's physiological as well as
chronological age, and realistic expectations in light of
the associated risk should be considered in any decision
regarding surgery.
Because of the multilevel, bilateral nature of the typi-
cal symptoms and pathology of lumbar stenosis and
spondylosis, the extent of the decompression required in
any given case can usually be determined by the changes
seen on the imaging studies. The technical goal of sur-
gery is decompression of the neural elements with main-
tenance of spinal stability. If one is overly aggressive with
decompression, such that the pars interarticularis or
facet joints are unduly compromised, iatrogenic instabil-
ity may result.
The concept of stability is very complex, and depen-
dent upon a number of factors. White and colleagues
define clinical instability as "the loss of the ability of the
spine under physiologic loads to maintain relationships
between vertebrae in such a way that there is neither
damage nor subsequent irritation to the spinal cord or
nerve roots and, in addition, no development of defor-
mity with excessive pain" (75). Models utilizing 2—col—
umn and 3—column concepts have been popular (76).
Spinal stability can be thought of as a spectrum bounded
by relative stability and relative instability, neither being
an absolute state. All patients have different variables
influencing whether their spine is "stable" for their
needs. These variables include individual spinal anat-
omy, weight, age, level of activity, quality ofbone, health
of discs and ligamentous tissues, and future physical de-
mands. The goal of surgery is generous decompression of
the neural elements while minimizing the loss of stabiliz-
ing inﬂuences for the spine.
If a patient is healthy and active, appears to exhibit
relatively good lumbar spine ﬂexibility, or suffers pri-
marily from lateral recess stenosis, bilateral multilevel
laminotomies with foraminotomies can be performed.
This will leave the bulk ofthe interspinous ligaments and
posterior elements intact, thereby retaining this compo-
nent of stability. Complete posterior, lateral, and fora-
minal decompression ofthe neural elements must still be
obtained, which can require more time at operation than

444 / CHAPTER 21
standard bilateral decompressive laminectomies (R. V.
Grewe, personal communication, 1989) (77). On the
other hand, if the patient is older, relatively inactive or a
higher surgical risk, or has significant ankylosis, simple
bilateral multilevel decompressive laminectomies with
medial facetornies may be in the patient's best interest.
Compression of the canal with surgical instruments
should be avoided (78).
In performing the laminectomy, great care should be
taken in removing the hypertrophied ligaments and lami-
nae. Adhesions may be present between the dura or
nerve roots and the overlying lamina and ligaments. The
dura may be easily torn, with injury to the tightly packed
nerve roots. Primary closure should be undertaken.
Some have advocated using a dural patch graft to enlarge
the lumbar subdural space, particularly ifthere is myelo—
graphic evidence of arachnoiditis. However, this is
usually not necessary if adequate posterior decompres-
sion is accomplished. Significant clinical stenosis—spon—
dylosis is unusual at LI and L2, and therefore the usual
decompression is done from L3 through L5. Although
exploration of each level of the epidural space is indi-
cated during the procedure, it is usually unnecessary tol
violate the intervertebral disc space unless frank disc
rupture is identified.
The indications for spinal fusion in conjunction with
decompression are controversial. However, primary fu-
sion is rarely indicated for simple degenerative stenosis
(57). Decompression and primary fusion for stenosis as-
sociated with degenerative spondylolithesis, scoliosis, or
a previous lumbar discectomy or laminectomy remains
more controversial, but we are generally conservative.
Early ambulation should be encouraged since pro-
longed bed rest in patients of this age group is conducive
to thrombophlebitis and pulmonary embolism (79). If
prolonged bed rest is required, a course of mini—dose hep-
arin or external pneumatic compression stockings have
been advocated to reduce the possibility of embolic dis-
ease (80,81). Heparin treatment involves 5,000 units of
aqueous heparin sodium given subcutaneously every 12
hours postoperatively as long as the patient is in bed.
However, while this program has proven to be reason-
ably safe, the efficacy has yet to be clearly determined.
RESULTS OF SURGERY
Following surgical treatment of cervical or lumbar ste-
nosis—spondylosis, approximately 25 percent of patients
will have excellent relief of all symptoms. An additional
50 percent will have varying levels of acceptable improve-
ment; 25 percent will obtain little or no relief. The onset
of the relief of pain can be rapid, with significant im-
provement being noted within 24 to 48 hours of surgery.
Rehabilitation is facilitated by reorganizing the personal
life of the patient, and by reducing the level of physical
activity commensurate with the patient's residual neuro-
logic status and personal priorities.
REFERENCES
1. Duvoisin RC, Yahr MD. Compressive spinal cord and root syn-
dromes in achondroplastic dwarfs. Neurology 1962;12:202-207.
2. Pennal OF, Schatzker I. Stenosis of the lumbar spinal canal. Clin
Neurosurg 1971;18:86-105.
3. Schlesinger RB, Traveras I M. Factors in the production of “cauda
equina" syndromes in lumbar discs. Trans Am Neural Assoc
1953;78:263-264.
4. Brodsky, AE. Post-laminectomy and post—fusion stenosis of the
lumbar spine. Clin Orthop 1976;! 15:130-139.
5. Scoville WB. Types of cervical disk lesions and their surgical ap-
proaches. JAMA 1966;196:479-481.
6. Spangfort EV. The lumbar disc herniation: a computer-aided anal-
ysis of 2504 operations. Acta Orthop Scand(supp\) 1972;142;l-95.
7. Eyring EI. The biochemistry and physiology of the intervertebral
disk. Clin Orthop 1969;67:16-28.
8. Coventry MB, Ghormley RK, Kernohan IW. The intervertebral
disc: its microscopic anatomy and physiology. II. J Bone Joint Surg
1945;27:233-247.
9. Bogduk N, Long DM. The anatomy of the so-called “articular
nerves" and their relationship to facet denervation in the treat-
ment oflow back pain. JNeurosurg 1979;51:172-177.
10. Cloward RB. The clinical significance of the sinu-vertebral nerve
of the cervical spine in relation to the cervical disk syndrome. J
Neurol Neurosurg Psychiatry l960;23:32l -326.
‘l. Roofe PG. Innervation of annulus ﬁbrosus and posterior longitu-
dinal ligament. Arch Neurol Psychiatr 1940;44:100-103.
12. Macnab l. Dall D. The blood supply of the lumbar spine and its
application to the technique of intertransverse lumbar fusion. J
Bone Joint Surg 1971;53:628-638.
13. Parke WW. Correlative anatomy of cervical spondylotic myelopa-
thy. Spine 1988;13:831-837.
14. Lees F. Turner I W. Natural history and prognosis ofcervical spon-
dylosis. BrMedJ 1963;2;1607-1610.
15. Roosen K, Grote W. Late results ofoperative treatment of cervical
myelopathy. In: Grote W, Brock M, Clar HE, Klinger M, Nau HE,
eds. Advances in Neurosurgery. Berlin/Heidelberg/New York:
Springer, 1980;69-77.
16. Cusick IF. Monitoring of cervical spondylotic myelopathy. Spine
1988;13:877-880.
17. Verbiest H. A lateral approach to the cervical spine: technique and
indications. J Neurosurg 1968;28:191-203.
18. Beatty RM, Fowler FD, Hareson I Ir. The abducted arm as a sign
of a ruptured cervical disc. Neurosurgery 1987;21:731-732.
19. Cloward RB. New method of diagnosis and treatment of cervical
disc disease. Clin Neurosurg 1962;8:93-132.
20. Viikari-Iuntura E, Ponas M, Laasonen EM. Validity of clinical
tests in the diagnosis of root compression in cervical disc disease.
Spine 1989;14:253-257.
21. Sheehan S, Bauer RB, Meyer IS. Vertebral artery compression in
cervical spondylosis. Neurology 1960;10:968-985.
22. Howe IR, Taren IA. Foramen magnum tumors; pitfalls in diagno-
sis. JAMA 1973;225:1061-1066.
23. Rowe CR. Cervical osteoarthritis. NEngl JMed 1963;268:1178-
1179, 1351-1353.
24. Cailliet R. Neck and Arm Pain, 2nd ed. Philadelphia: F.A. Davis
Co., 1981.
25. Ferguson RI, Caplan LR. Cervical spondylitic myelopathy. Neurol
Clin 1985:3:373-382.
26. Boijsen E. Cervical spinal canal in intraspinal expansive processes.
Acta Radial 1954;42:101-109.
27. Pavlov H, Torg IS, Robie B, I ahre C. Cervical spinal stenosis:
Determination with vertebral body ratio method. Radiology
1987;164:771-775.
28. DiChiro G, Fisher RL. Contrast radiology of the spinal cord. Arch
Neurol 1964;! 1:125-143.
29. Roberson GH, Llewellyn HI, Taveras IM. The narrow lumbar
spinal canal syndrome. Radiology 1973;107:89-97.
30. Uden A, Iohnsson K-E, Ionsson K, Petterson H. Myelography in

CHAPTER 22
Princi les 0fNeur0surgery,
edite by Robert G. Grossman. R0senberE© 1991.
Published by Raven Press, Ltd., New Yor .
Traumatic Lesions of the Spine and Spinal Cord
Reinder Braakman
Incidence, 447
Associated Injuries, 448
First Aid and Transport, 448
Radiography, 449
Cervical Spine, 449
Thoracic and Lumbar Spine, 449
Computed Tomography, 450
Myelography, 450
Magnetic Resonance Imaging, 450
Injuries of the Cervical Spine, 450
General, 450
Upper Cervical Spine, 450
Lower Cervical Spine, 451
Injuries of the Thoracic, Thoracolumbar, and
Lumbar Spine, 455
Injuries to the Cord and Cauda, 456
Cause, 456
This chapter on injuries of the spine emphasizes injuries
producing a neurologic deficit as a result of the involve-
ment of the cord and cauda, roots, or both. The involve-
ment of these structures usually occurs at or near the
level of the injury.
Lesions of the cord or cauda may be complete or in-
complete (partial). The complete paralysis of both lower
limbs that may result from injuries to the spine is termed
paraplegia, while incomplete lesions are designated as
paraparesis. When all four limbs are involved, tetraple-
gia and tetraparesis are the internationally accepted
terms, although the term quadriplegia is also often used.
The term paraplegia is also used in a more general way to
indicate all severe cord lesions at a more or less recogniz-
able level of the cord. Both paraplegic and tetraplegic
patients are treated in paraplegic units, and doctors who
dedicate themselves to the management of all patients
with cord injuries call themselves paraplegists.
R. Braakman: Departmentof Neurosurgery, University Hos-
pital Rotterdam-Dijkzigt, Erasmus University Rotterdam,
Rotterdam, The Netherlands.
447
Spinal Shock, 457
Pathology, 457
Complete Cord Lesions, 457
Incomplete Lesions of the Cervical Cord, 458
Incomplete Lesions of the Thoracic Cord, 459
Incomplete Lesions of the Conus and Cauda, 459
Progressive Cord Lesions, 459
Fra11kel's Classification, 460
Prognosis, 460
Mortality, 460
Recovery of Function in Survivors, 460
Treatment,461
General, 461
Cervical Spine, 462
Thoracic Spine, 464
Thoracolumbar Spine, 464
References, 465
INCIDENCE
The incidence of traumatic para— and tetraplegia
ranges from 10 to 50 new patients per year per million
population (1-3). The lower cervical region (C4—7) and
the thoracolumbar junction (T11—L1) are the most fre-
quent sites of traumatic cord damage. Most of the pa-
tients experiencing such damage are under 30 years of
age, and more men are involved than women. In indus-
trialized countries, car, motorcycle, bicycle, and pedes-
trian accidents account for between 30 and 50 percent of
the total number of such paralyzing injuries. Industrial
accidents account for another 20 to 40 percent. In the
past, mine injuries—rnainly involving the thoracolum—
bar region—were a major cause of para— and tetraplegia.
Their number has decreased in recent decades, but other
injuries, mainly to the cervical spine, due to falls from
ships and buildings have increased. Elderly people are
particularly affected by domestic accidents, including
falls down ﬂights of stairs. The incidence of cord injuries
resulting from suicide attempts is also increasing in
many countries.

448 / CHAPTER 22
Spo1ts i11juries of the ceivical spine l1ave beco1ne i11-
creasi11gly co1n1no11. They 1nay be due to i11jury i11 such
sports as football (4), wrestli11g (5), gy1n11astics, a11d
l1ang—gliding (6), or may occur after falls fro111 l1orses, in
tra1npoli11e ju1npi11g, i11 raci11g accidents, a11d particu-
larly fro1n dives i11to shallow water a11d fro1n surfboard
accide11ts. Most of the affected patients are u11der 20
years of age.
Spinal cord injuries i11 children are u11co1n1no11 i11 coin-
pariso11 witl1 the incidence i11 teenagers a11d adults. Birth
trau111a a11d falls fro111 trees a11d walls are the 111ajor
causes of these injuries i11 children (7).
Largely as a result of the increase i11 the 11u1nber of
traffic a11d SpO1’tS accidents, a11d the decrease i11 11u1nber
of 1ni11i11g accidents, tetraplegia a11d tetraparesis are
nowadays about as equally co1n1no11 as paraplegia a11d
paraparesis (l).
ASSOCIATED INJURIES
Approximately l1alf of all paraplegic a11d tetraplegic
patients l1ave other injuries (8). These are 1nore co1n1no11
i11 industrial a11d i11 traffic accidents than i11 sports a11d
do1nestic accidents. Often the head is involved; thus,
wl1ile there 1nay be only 1ni11or lesio11s of the scalp or
fractures of the vault a11d skull base, severe i11volve1ne11t
of the brain also occurs, pa1ticularly i11 traffic accidents.
About l1alf of all injuries associated witl1 paraplegic
a11d tetraplegic trau1na involve the thorax. 111 the 1najor—
ity of cases these are fractured ribs, and one in eve1y five
patients l1as a pul1no11ary co11tusio11, l1e1notl1orax, or
p11eu1notl1orax. Such injuries may necessitate the pa-
tie11t's ad1nitta11ce to a11 intensive care u11it. Trau1natic
heart lesio11s are rare. I11 tl1oracolu1nbar injuries, the
most common associated lesio11s are diaphragmatic l1er—
nia, laceratio11 of the liver, 1upture of the spleen, a11d
perforation of the intestine.
About one i11 eve1y te11 patients witl1 a11 injury of the
spine l1as a fracture of the pelvis, wl1icl1 may be asso-
ciated witl1 1upture of tl1e urethra a11d may cause serious
problems i11 bladder management. One of every three
patients experiencing paraplegic trauma also l1as a frac-
ture oftl1e upper or lower li1nbs or botl1. Because oftl1ese
. associated injuries, the physical examination of paraple-
gic a11d tetraplegic patients should be repeated every
hour duri11g the first few hours after the pa1alyzi11g i11-
jury, particularly with regard to the circulatoiy system,
respiratoiy system, a11d abdomen (9).
FIRST AID AND TRANSPORT
The principal aim of first aid is the preservation of life
a11d the reductio11 of risk to the patient. Careful first aid
followed by immediate transpo1t to a well—equipped l1os—
pital u11it should be the aim of all concerned. 111 the case
of spinal cord injury, proper first aid ca11 prevent what is
primarily partial damage to the cord fro1n becoming a
complete lesio11. The first step i11 this should be to i11-
st1uct the injured individual 11ot to move. Additionally, a
free aiiway l1as to be established a11d, if necessary a11d
possible i11 1nultitrau1na patients, hemo1rhage 1nust be
stopped. The cardiovascular system should be assessed,
sl1ock recognized, a11d the thorax, extremities, a11d abdo-
men examined for associated injuries. The first 111edical
attendant to see the patient should tiy to ascertain
whether motor a11d senso1y deficits are complete or par-
tial. For 1nedical ﬁrst—aid personnel, the level of a cord
lesio11 may be somewhat difficult to ascertain, particu-
larly if the injured patient is unconscious following the
injury.
If the patient 1nust be moved froin the site of tl1e acci-
dent to a 1nore convenient locatio11 before a11 ambulance
or other transport facility a11ives, all lifting should be
do11e slowly, by at least four members of the first—aid
party, a11d the patient should be lifted "as one piece"
(10,11). The patient should also be kept warm. Hard
objects, such as keys and ligl1ters, 1nust be removed froin
the pockets of the patient as a first step toward avoiding
the development of pressure sores duri11g transport (10).
Pressure sores ca11 be prevented duri11g transport by the
use of foam 1ubber mattresses and the application of
pads of soft material between the knees a11d ankles a11d
underneath the calves. Heat a11d extreme cold should be
avoided during transport because para— and in particular
tetraplegic patients are poikilothermic.
Usually, spi11e—i11jured patients are transfeired directly
to the nearest well—equipped hospital a11d subsequently
to a spi11al—i11jury u11it, either by ambulance or l1eli—
copter. During this transpoit, the patient should be coin-
fortable. For this pu1pose, special a1nbula11ce—tra11sport
stretcl1ers are available. Many 1nultitrau1natized patients
require oxygen administered via a mask or nasal catl1—
eter.
Whether patients who probably l1ave a spinal injury
but are unconscious should be transported in the supine
or in the se1niprone lateral position is still a matter for
discussion. Vomiting by a patient i11 the supine position
may cause airway obst1uctio11, i11 which case the se1ni—
pro11e lateral position may be advisable.
During the transport of spine—injured patients, the loss
of vasomotor control causes pooling of blood i11 the
widely dilated vessels of tl1e abdomen, lower li1nbs, vis-
cera, and retroperitoneal region, and in the neigl1bor—
hood of any fractures. This may lead to l1ypote11sio11.
Therefore, the e1nerge11cy—roo1n treatment of hypote11—
sio11, the control of continuing hemoirhage, a11d provi-
sions for adequate respiration are of pri1ne importance.
The treatment ofposttraumatic sl1ock takes absolute pri-
ority i11 spi11e—i11jured patients. Ifblood is unavailable for
transfusion, blood substitutes can be used. Most spine-
i11jured patients need fro1n l to 2 liters of blood as a

result of neurogenic vasomotor shock. Iftransfusions are
necessary, the ju gular—fillin g pressure and the blood pres-
sure rnust be checked. The overtransfusion of blood to
and overhydration of spine—injured patients is not un-
common; this results in dangerous overfilling ofthe vas-
cular systern (9).
A nasogastric tube should be passed to aspirate the
stomach contents in all patients with severe cervical or
upper thoracic cord injuries. Most spine—injured patients
do not require bladder catheterization within the first 8
hours after their injury (10,12), but any patient who re-
ceives intravenous ﬂuids should have a Foley catheter
inserted or, preferably, should be subjected to intermit-
tent sterile catherization (12,13). All tetra— and paraple-
gic patients should—during the first few days—be
treated in an intensive care ward.
The accurate diagnosis of a spinal lesion requires a
detailed history of the mechanism of injury, and for this,
careful neurologic examination and good quality radio-
graphs are essential. A detailed but concise neurologic
examination will reveal whether the patient has a corn-
plete, incomplete, or minor cord and/or root lesion. In
most cases, the extent of the patient's neurologic deficit
and the level of the injury can be categori/ed at an early
posttraumatic stage. The neurologic examination should
be repeated every hour to detect early improvement or
early deterioration. Special attention must be given to
important unfavorable prognostic signs, such as a pro-
tracted plantar ﬂexion response and priapism, and to
favorable signs, such as retention of sacral sensibility and
deep sensibility in the toes.
RADIOGRAPHY
In any request for the radiographic examination ofthe
spine of a spine—injured patient, the area of suspected
fracture or dislocation must be clearly defined to the ra-
diographer, particularly when the injury involves the
cervicothoracic or thoracolurnbarjunctions. Ifthis is not
done, the main abnormality may lie at the edge of the
radiograph.
Cervical Spine
When patients have cervical spinal injuries, films
should be made of the entire cervical spine, and C7
should always be visible on the lateral radiograph. The
first lateral picture must be taken with the patient on the
transportation stretcher. To avoid superimposing the
shadows ofthe patient's shoulders, gentle traction on the
arms may be necessary to depress the shoulders. These
first lateral radiographs provide the best immediate in-
formation about the injury, since they permit the diag-
nosis of all major traumatic lesions of the cervical spine
TRAUMATIC LESIONS / 449
(14-16). The lateral films should be made with the pa-
tient horizontal in order to safeguard the spinal cord. In
addition, anteroposterior films are mandatory, and
oblique views may occasionally be useful. However,
some lesions may be difficult to visualize owing to bony
overlap and location. If traction on the arms does not
overcome superimposition of the shoulders, pluridirec—
tional tomography may be useful but requires significant
manipulation of the injured patient with the risk of more
instability and neural damage (16,17). In evaluating the
condition ofthe cervical spine, it is important not only to
recognize anatomic details, but also to pay particular at-
tention to normal topographic relationships and to fol-
low the course of the bony spinal canal in any projection
of the spine. The course of the canal should be smooth
and harmonious, without any sudden shift. Polyto1nog—
raphy provides the most useful information in fractures
of the odontoid process and in the evaluation of facet
fractures or facet subluxations or dislocations, especially
where unilateral. However, in the last decade computed
tomography (CT), with its capabilities for axial display
and reformatting images in sagittal, coronal, or oblique
planes without additional patient motion or additional
radiation exposure, is considered superior in most cases
of cervical spine injury with cord involvement.
In a significant number of lesions of the cervical cord,
radiographs of the spine are negative. In these patients,
hyperextension is the most common causative mecha-
nism of the lesion, whereas weakness of the interverte—
bral disc is an important contributory factor in the
"pinch" type mechanism of cord lesion. After a hyperex-
tension injury the spine is spontaneously realigned, and
the hyperextension mechanism can be detected only
from a widening of the prevertebral space (18). Another
aspect to look for, if there are no radiologic signs of
trauma to the spine, is a small natural size of the spinal
canal. In patients with a diminished sagittal diameter of
the spinal canal, minor displacements may cause corn-
pression of the cord and major neurologic deficits
(14,16).
Thoracic and Lumbar Spine
Anteroposterior (AP) and lateral views ofthe damaged
part of the spine may give an indication of the type of
injury and of the stability of the lesion. On the AP radio-
graph, particular attention should be paid to the interpe-
dicular distance, which in unstable injuries is widened in
comparison with the corresponding distances above and
below. A good impression of stenosis of the spinal canal,
however, cannot be obtained, even if additional lateral
tomographic views are available. Computed tomograms
provide far more detail, and in most cases the stenosis of
the spinal canal exceeds the amount expected on the ba-
sis of plain radiographs.

Computed Tomography
Computed tomography is useful in differentiating
compression fractures from burst fractures. Computed
tornograrns are quite helpful in diagnosing Jefferson's
fractures, pedicle fractures, laminar fractures, and frac-
tures of the spinous process. Atlantoaxial rotary disloca-
tions are also well visualized on CT scans. The superior
depiction ofbony detail with CT allows clear dernonstra—
tion of fracture lines, particularly in posterior neural
arch fractures. Three—dimensional reconstruction may
be helpful. Computed tomography evaluates the spinal
canal and the integrity of the thecal sac.
Myelography
Contrast enhancement of the spinal canal prior to CT
scanning may be useful in assessing the effect of the spi-
nal injury on the thecal sac. Water—soluble myelography
is worthwhile if the patient's neurological deficit is not
consistent with the level of the vertebral injury shown on
the plain radiographs and on CT (17). If myelography is
performed, the combination with CT is almost indispens-
able for differentiating between cord swelling and cord
compression by extramedullary compressive agents.
Currently, however, rnyelography can usually be re-
placed by magnetic resonance imaging.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) provides irnpor—
tant data concerning the nature and extent of injury to
the spinal cord and reveals the spinal epidural and sub-
arachnoid spaces. An excellent way of assessing spinal
cord damage and ligamentous injury, it provides a de-
tailed overview of the traumatized region in a shorter
time period than the usual radiological evaluation, and it
eliminates the use of intrathecal contrast material or ion-
izing radiation (17). MRI can differentiate between cord
swelling and compression of the cord from bone, disc, or
blood, and can also reveal traumatic intervertebral disc
protrusions. Increase in the signal, especially in T2-
weighted images, implies increased water content of the
spinal cord following injury. Cord swelling may show
clearly on sagittal views. With appropriate surface coils,
the damage to the cord can be more adequately demon-
strated.
Intact ligaments are difficult to see with MRI, but rup-
tured ligarnents are easily identified. Damage to the pos-
terior ligamentous complex may influence the therapeu-
tic and surgical management. A disruption of the
anterior longitudinal ligament can also be shown.
MRI can only be performed in medically stable pa-
tients. Severely injured patients who require extensive
mechanical and personnel support are particularly diffi-
cult to image with MRI, owing to the presence of metal
in most support apparatus.
INJURIES OF THE CERVICAL SPINE
General
Blunt injuries of the cervical spine may be caused by
direct or indirect force. Direct forces, such as from a
falling object hitting the neck, act directly on a vertebra.
Commonly, the result is a fracture of a spinous process
or vertebral arch.
Lesions resulting from indirect forces are caused by
movements of the spine that extend beyond the physio-
logical range, such as hyperﬂexion and hyperextension
(sometimes indicated as hyperretroﬂexion or hyperde—
ﬂexion) (14,19). Indirect forces may also be shear forces
that displace the vertebrae parallel to each other, or
forces acting along the axis of the cervical spine, such as
compressive forces that approximate the skull and the
trunk or distractive forces that separate them. Cornpres—
sive axial forces may in one case produce compression of
the atlas and in another produce compression of a verte-
bral body—differences that are probably due to the ac-
tion of additional forces. Lateral hyperﬂexion and hy-
perrotation also play a part in cervical spinal injury.
There are often combinations of excessive movements,
such as hyperﬂexion and axial compression or axial dis-
traction, that act to injure the cervical spine. These corn-
binations determine the type of injury to the cervical
spine. Sometimes a series of unphysiological rnove—
ments, such as hyperﬂexion followed by hyperextension,
or vice versa, causes the injury (14).
Upper Cervical Spine
The atlas functions as a bony rneniscoid between the
occiput and the axis. The transverse ligament that origi-
nates bilaterally frorn the medial aspect of the lateral
mass of the atlas keeps the odontoid process in its place.
Atlas Fracture
An atlas fracture is usually the result of hyperexten-
sion, which causes the type I fracture, confined to the
posterior arch, or the result of vertical compression re-
sulting in a type II fracture, involving both arches and
crossing the equator of the atlas. Jefferson's fracture is a
fracture of the anterior and posterior bony arches of Cl
with lateral displacement of the lateral masses of Cl onto
C2. Although a Cl fracture is generally dismissed as a
relatively innocuous injury, follow—up studies have re-
vealed that many patients have persistent symptoms of
dysaesthesia, neckpain, and/or neck stiffness (20).

Anterior Atlantoaxial Dislocation
In anterior atlantoaxial dislocations, the distance be-
tween the anterior arch of the atlas and the intact odon-
toid process exceeds 2 to 3 mm in adults and 4 to 5 mm
in children. Such dislocations are particularly seen in
congenital anomalies and in rheumatoid arthritis but are
occasionally due to a rupture of the transverse ligament.
If, as in the rare case, the cord is involved, the trauma is
usually fatal.
Fracture of the Odontoid Process and
Hangman ’s Fracture
The two most common types of injury to the upper
cervical spine are fracture of the odontoid process and
hangman's fracture. According to Nachemson (21) and
others, fractures of the odontoid process account for 10
percent of all cervical spine fractures. The most common
causes of fractures of the odontoid process are falls on
the head and traffic accidents. Howorth and Petrie
ascribe odontoid fractures to sudden forward or back-
ward movements of the head with respect to the trunk
(Fig. 1) (22). In the case of forward displacement of the
head, the broken—off odontoid process appears to be
sheared off by the transverse ligament, whereas in back-
ward displacement it is sheared off by the anterior arch
of the atlas. Many patients with odontoid fractures have
FIG. 1. Fracture of the odontoid process with posterior atlan—
toaxial displacement in a 66-year-old man who fell down a
flight of stairs. (From reference 14, with permission.)
TRAUMATIC LESIONS / 451
head injuries or mandibular fractures. Pain in the poste-
rior part of the neck and limited motion of the neck are
the most common symptoms. These fractures are often
missed because the patient is initially unconscious or in-
toxicated or has associated trauma to the head. Patients
with such injury may not consult a physician until sev-
eral days after the accident. Neurologic signs and symp-
toms—mainly signs ofpyramidal tract damage—are en-
countered in only a minority of cases. The diagnosis may
be missed on plain radiographs and polytomography
may subsequently be necessary. Computed tomography
is usually not helpful. On the plain radiographs, errone-
ous diagnoses of odontoid fractures in adults are caused
by the superimposed outlines of the two atlantoaxial
joints on lateral radiographs and of the anterior and pos-
terior arches of the atlas, the teeth, or the upper surface
of the tongue on anterior and posterior radiographs.
In the hangman's fracture, or traumatic spondylolis—
thesis of C2, the fracture occurs at the base ofthe pedicles
and results in an anterior dislocation ofthe body of C2 in
relation to C3. This type of fracture dislocation is
currently very common, occurring in motor—vehicle ac-
cidents in which the patient's face comes in contact with
the car's windshield and the neck is subsequently sharply
extended and axially compressed (Fig. 2). The cord
usually escapes damage because the sagittal diameter of
the spinal canal is not reduced.
Lower Cervical Spine
Distractive Hyperﬂexion
In distractive hyperﬂexion, a blow on the occiput from
below separates the spinous processes and overstretches
the posterior ligaments and the capsules of the interver—
terbral articulations. These may be torn, and a hyperﬂex-
ion sprain (l4,23) may develop, with a kyphotic angula-
tion of the spine (Fig. 3). This lesion is usually located
between C2 and C4 in younger subjects, and between C4
and C7 in adult subjects. Hyperﬂexion sprains are also
called anterior subluxations, with the term subluxation
commonly being used to cover a situation in which there
is partial disruption ofthe articular surfaces. Because it is
very difficult to establish a borderline between maximal
physiological excursion and partial disruption of the sur-
faces, the diagnosis of subluxation has led to much con-
fusion and to the incorrect treatment of spinal injuries.
Consequently, we prefer not to use this term, particu-
larly if the traumatic nature of a partial disruption is
definite.
Facet Interlocking
Facet interlocking occurs if the articular facets lose
contact, override, and, while springing back after injury,

452 / CHAPTER 22
FIG. 2. (A) Hangman's fracture with marked anterolisthesis at C2—3 in a 55-year-old man involved in a
car accident; (B) the site of the fracture; (C) mechanism of injury.
FIG. 3. Hyperflexion sprain C4—5 in a 22-year-old woman.
Diving accident.
become interlocked. This interlocking may be unilateral
(Fig. 4) or bilateral (Fig. 5). Facet interlocking is an exam-
ple of a dislocation, a complete and permanent disrup-
tion of the normal contact between articular surfaces.
The most common causes of bilateral and unilateral
interlocking are falls from steps or stairs, traffic acci-
dents, and athletic injuries (14). The destruction of liga-
rnents and discs is usually less extensive in unilateral
than in bilateral facet interlocking. In either case, frag-
ments of a ruptured disc may be found in the spinal
canal (24). The clinical symptoms of facet interlocking
vary from neck pain without neurologic impairment to a
complete and permanent cord lesion. The neurologic def-
icit is more severe in bilateral than in unilateral inter-
locking owing to greater narrowing of the spinal canal.
About half of all patients with bilateral facet interlocking
have a complete cord lesion. Additional factors in facet
interlocking that predispose to cord lesions are a small
natural width of the spinal canal and cervical spondylo—
sis, with consequent narrowing of the spinal canal.
The diagnosis of bilateral facet interlocking is made
radiologically; the characteristic picture can hardly be
missed (Fig. 5). Unilateral interlocking is characterized
by an abrupt shift in the column of interyertebral joints
on the affected side, visible on a lateral radiograph. How-
ever, in many cases interpretation of the radiographs of
facet interlocking is not as easy as is indicated by Figure

FIG. 4. Unilateral interlocking C4-5 in a 21-year-old male.
Note the abrupt shift in the column of intervertebral joints on
one side. This picture was taken during skull traction and
displays the rupture of the anterior and posterior longitudinal
ligaments at the C4-5 disc space and the capsules of the
intervertebral joints.
4. For example, in about one—third of our patients with
unilateral interlocking, the presence of facet interlocking
was missed. Stereoscopic views, oblique projections, and
lateral tomograms may therefore be helpful for detecting
and localizing an instance of interlocking.
FIG. 5. Bilateral interlocking C5—6. Note the parallel displace-
ment of the cranial vertebral body as is seen in older patients
with fissures in the intervertebral disc.
TRAUMATIC LESIONS / 453
Axial Compression
In the case of axial compression of the lower cervical
spine, the simplest type of injury is a slight wedge—com—
pression fracture of the vertebral body, which may give
rise to some kyphotic angulation. Such wedge—cornpres—
sion fractures must be differentiated from the ﬂattening
of vertebral bodies that results from the degenerative
changes in cervical spondylosis. The latter platysp0ndy—
Zia is particularly observed in the vertebral bodies of C5,
C6, and C7. Such degenerative changes, and the super-
imposition of transverse processes on the lateral radio-
graph, may cause errors in interpretation and simulate
nonexistent compression fractures of vertebral bodies.
More severe axial forces produce a burst fracture (Fig. 6).
Compressive Hyperﬂexion
In compressive hyperﬂexion, a blow on the"3ack of the
neck is transmitted along the spine and may lead to a,
fracture dislocation. In the more severe forms of com—l
pressive hyperﬂexion, the anterior part of the vertebral
body tends to be pinched off ( teardrop fracture), while
the posterior part tends to be displaced backwards into
the spinal canal (Fig. 7) (l4,24—26). The vertebral body
often shows vertical fractures and in severe axial corn-
pression the result is a burst fracture. The backward dis-
placement of the posterior part of the body is facilitated
by a rupture of the caudally bordering disc. Compressive
hyperﬂexion injuries are notorious for producing a high
incidence of spinal cord lesions due to narrowing of the
spinal canal. More than half of our patients with such
injuries had complete cord lesions (14).
Traumatic Disc Prolapse
Many cases of traumatic disc prolapse in the lower
cervical spine have been reported in connection with cer-
vical spine injuries, although the incidence of this injury
remains uncertain. Such prolapse occurs particularly in
combination with distractive and compressive hyper-
ﬂexion injuries (24,26). These disc prolapses can be re-
vealed on CT—myelography and on MRI (17). The trau-
matic disc prolapse has been linked with the anterior
cervical cord syndrome (26). We have seen such pro-
lapses in combination with all types of cord injury.
In hyperextension injuries the disc is often torn, but
this tearing is mainly anterior, and it is highly improba-
ble that in these injuries the disc ever prolapses into the
spinal canal.
Disruptive Hyperextension
The relative weakness of the intervertebral disc is an
important contributing factor in the genesis of disruptive

454 / CHAPTER 22
FIG. 6. Computed tomogram of a burstfracture at C5. Twenty-three-year-old patient fell from a ladder
and had only a slight reversible cord deficit.
hyperextension injuries of the spinal cord, particularly in
elderly patients in whom the disc has been completely
bisected by the spondylotic process of secondary joint
formation.
Forced hyperextension of the cervical spine may result
in rupture of the anterior longitudinal ligament and of
the intervertebral disc, with a signiﬁcant displacement of
the vertebral body (Fig. 8) (14,19). The portion of the
spine above the separation moves backwards and
pinches the cord between the inferior posterior border of
the dislocating body and the leading edge of the arch of
the vertebra below (Fig. 9). When the traumatic force is
removed, however, there is commonly spontaneous re-
alignment. Subsequent radiographs usually appear nor-
mal, although there may be a widening of the shadow of
the prevertebral soft tissues, outlined anteriorly by the
airway and posteriorly by the cervical skeleton (18).
Such injuries are often associated with the presence of
cervical spondylosis. In the spondylotic segments, the
sagittal diameter of the spinal canal is smaller than aver-
age and, as a result, the cord has less "play" within the
spinal canal, with consequent earlier pinching of and
damage to the cord. Canals that are constitutionally
narrow may also predispose patients to serious neuro-
logic damage from minor spine injuries.
FIG. 7. The compressive hyperflexion mechanism. Left: be-
fore injury, showing C5—C6—C7; middle: first stage of injury.
The compressive hyperflexion force causes the spine to
move through an arc, displacing C6 backwards with respect
to C7 and rupturing the corresponding intervertebral joint
capsules and the C6—7 disc. A disc extrusion may result;
right: last stage. There is marked widening of the C6—7 inter-
vertebral joint space; G6 has been displaced backward with
disruption of the posterior part of the intervertebral disc; the
anteroinferior margin of G6 has broken off, although it re-
mains in a normal relationship with C7. The C5—6 disc is
usually intact but may be torn. The articular processes remain
intact.
In patients with hyperextension injuries, facial
wounds, broken mandibles, and nasal bone fractures are
common.
Compressive Hyperextension Injuries
Compressive hyperextension injuries are character-
ized by compression fractures of the articular processes
of the vertebrae and anterolisthesis of the upper vertebral
body relative to the lower body (Fig. 10) (14,19). Such
fracture dislocations occur particularly in younger pa-
tients. The hangman's fracture is an example of a hyper-
extension fracture dislocation of the upper cervical
spine, but these injuries also occur in the lower cervical
spine. Since the arch of the dislocated vertebra usually
fractures before there is anterior displacement of the ver-
FIG. 8. Hyperextension sprain—even dislocation—in a 40-
year—old male patient with ankylosing spondylitis. Marked de-
hiscence at the C5—6 level. (From reference 14.)

FIG. 9. Pinching of the cord. The anterior longitudinal liga-
ment is ruptured as a result of distractive hyperextension and
posteriorly directed shear forces. The cranial vertebra is dis-
placed backwards and the spinal cord is pinched. After the
injury the spine usually resumes its original position. (From
reference 14.)
tebral body (Fig. 10), a bony pincers mechanism that
would compress the cord in the sagittal direction does
not occur (14). Therefore, the neurologic deficit in the
majority of cases is either mild or nonexistent, in con-
trast to compressive hyperﬂexion injuries in which the
arch remains intact and the cord is often subjected to
bony pinching (Fig. 7).
INJURIES OF THE THORACIC,
THORACOLUMBAR, AND LUMBAR SPINE
Most injuries to the thoracic (T1 to T10) and thoraco—
lurnbar (Til to L1) spine are due to automobile and
motorcycle accidents, falls, suicide attempts, and mine
accidents (1,3). Most patients are young. Injury to the T1
to T10 and Til to L1 vertebrae occur with about equal
frequency.
The spinal injury is often associated with severe rnulti—
ple injuries to the head, chest, abdomen, and limbs (8).
FIG. 10. The mechanism in compressive hyperextension inju-
ries. The trauma forces the head backwards and downwards,
resulting in a hyperextension fracture dislocation with fractur-
ing of the articular processes and marked forward slipping of
the corresponding vertebra. In many cases, the anterior longi-
tudinal ligament is ruptured. The sagittal diameter of the spi-
nal canal is not reduced. Consequently most of these patients
have no neurological deficit.
TRAUMATIC LESIONS 455
FIG. 11. The three columns according to Denis: top: anterior
column; middle: middle column; bottom: posterior column.
The most common types of injury are the burst fracture
with displacement of a brol<en—off fragment of the poste-
rior part of the vertebral body into the spinal canal, and
the fracture dislocation.
Currently, the most common classification of these
injuries is based on the three—column concept by Denis
(Fig. 11). About 50 percent of these injuries are burst
fractures resulting from axial compression with damage
to the anterior and middle column. The spinal canal is
narrowed, due to the displacement of the broken—offpos—
terior part of the vertebral body (Fig. 12). In about 50
percent of patients with a burst fracture, there is neuro-
logical involvement that may be incomplete or corn-
plete.
In the second most common type of injury, the frac-
ture dislocation, all three columns of the spine are
disrupted, due to translation forces in combination with
axial compression or distraction and/or torsion. Radio-
logically, there is usually an anterior dislocation and an-
gulation of the cephalad vertebra with detachment of an
anterosuperior wedge fragment from the body of the
lower vertebra. This results in a marked deformation of
the spinal canal (Fig. 13). About half of the patients have
complete cord or cauda lesions, and in another 25 per-
cent of these cases partial cord or root involvement ex-
ists.
Compression fractures of the vertebral body usually
do not show neurological involvement, because the spi-
nal canal is not compromised. Extension injuries are
rare.
About 25 percent of all cases of severe traumatic spi-
nal cord injury involve injuries between T1 and TIO. If

456 / CHAPTER 22
FIG. 12. Computed tomogram of a burst fracture of the lum-
bar spine with marked stenosis of the spinal canal. This pa-
tient, however, had only moderate involvement of the cauda
equina. Note the fracture line in the spinous process. During
operation via a posterolateral approach the dura proved to be
torn and many cauda roots were found in the fracture cleft in
the spinous process.
there is neurological deficit, it is due to cord involve-
ment. In another 25 percent, the thoracolumbar area
from T10 to LI is involved, and neurological deﬁcit is
due to damage ofthe conus, the epiconus, and also cauda
roots.
FIG. 13. Fracture dislocation of the thoracolumbar spine.
Only a small percentage of injuries to the spine occur
between L2 and L5. These injuries are mainly burst inju-
ries or fracture dislocations. They may be due to direct
impact or to vehicular accidents. Acute traumatic spon-
dylolisthesis is highly uncommon. A characteristic in-
jury is the so—called seat—belt injury, in which a person
suffers a sudden deceleration in an automobile or air-
plane crash, with the kinetic energy of the upper trunk
and torso causing sudden ﬂexion and distraction cen-
tered in the mid—lumbar spine around the fulcrum of the
seatbelt on the anterior abdominal wall (27).
INJURIES TO THE CORD AND CAUDA
Cause
The neurological deficit in injuries ofthe spine may be
due to lesions of the cord, cauda, or roots, orto two or all
three of these. Neurologic lesions of the spinal cord and
cauda may be temporary results of spinal shock or per-
manent injuries resulting from structural damage. Per-
sisting damage to the cord or cauda may be due to corn-
pression, overstretching, hemorrhage, traumatic edema,
and microcirculatory disturbances.
Compression of the cord or cauda may occur either
from opposite sides (pinching) or from one side (contact
pressure) (14). Such compression is commonly exerted
by bone but may also be due to a hematoma, aprolapsed
intervertebral disc, or infolding ligaments. In cervical spi-
nal injuries there may be permanent pinching, such as
from bilateral facet interlocking (Fig. 5) or temporary
pinching, such as from hyperextension sprains (Fig. 8).
One—sided compression may be exerted by a herniated
intervertebral disc, particularly in patients under 45
years of age with disruptive hyperﬂexion or compressive
hyperﬂexion injuries. This type of compression may also
be due to bone displacement, as in teardrop fractures
(Fig. 7) and burst fractures (Fig. 6).
In thoracolumbar injuries, the most common causes
of cord and cauda damage are deformation of the spinal
canal in fracture dislocations (Fig. 13) and compressing
bone fragments in the spinal canal, as in burst fractures
(Fig. 12), that produce either contact pressure or
pinching.
Overstretching occurs when the cord is drawn out over
the anterior wall of the spinal canal, as in the case of a
teardrop fracture (l4,25) (Fig. 7), and also in excessive
skull traction.
Traumatic edema of the cord usually starts to develop
a few hours after an injury. As a result of the edema, the
cord swells and is compressed within the spinal canal.
Whether this causes only a temporary impairment of
cord function or permanent damage remains obscure.
Cord damage has also been attributed to local impair-
ment of the blood supply to the cord or to impaired

venous drainage (28). However, while the vertebral ar-
tery may be damaged in cervical injuries, ruptures and
thrombosis of the artery are rare (28). Transient symp-
toms have been attributed to a relative vertebral artery
insufficiency (29) resulting from compression or spasm
of the vertebral artery or of the anterior spinal artery.
Microcirculatory responses to trauma deserve special at-
tention, because they might be amenable to medical
treatment.
In severe cord injuries, the center of the cord may
show cord infarction with hemorrhagic necrosis.
Spinal Shock
The term spinal shock was introduced by Marshall
Hall in 1841 to indicate the state of transient inexcita—
bility or hypoexcitability of the isolated spinal cord be-
low the level of a transection of the cord (10). Spinal
shock may be owing to the loss of facilitation from de-
scending tracts, to persisting inhibition from below the
transection acting upon extensor reﬂexes, or to the ax-
onal degeneration of interneurons (10). The intensity
and duration of the shock depend on the level of the
organism on the vertebrate scale; the higher the degree of
cerebral development, the greater the shock. In spinal
shock, the motor paralysis below the level of the lesion is
at first of a ﬂaccid type, even if the paralysis is of the
upper motor—neuron type. All cutaneous and tendon re-
ﬂexes below the level of the shock are greatly depressed
or abolished, although bulbocavernosus and anal re-
ﬂexes may persist. When the shock subsides, the reﬂexes
return. In humans, the duration of the areﬂexia varies,
with reﬂex activity sometimes appearing within a period
of three or four days in children or after three to six
weeks in adults. The first reﬂexes to return are the anal
and bulbocavernosus reﬂexes (14). As a rule, further re-
ﬂex return is in a headward direction. However, return
of the knee jerk reﬂex may precede that of the ankle jerk.
Pathology
The primary traumatic lesion, resulting directly and at
the moment of injury from a mechanical impact on the
spine, includes laceration of the dura and meninges, ex-
tradural, intradural, and subaraclmoid hemorrhage, and
damage to the cord and spinal roots.
Most spinal cord lesions are spread over more than
one segment. Traumatic extradural hemorrhage is rare
and is hardly ever a primary cause of compression of the
cord. Subdural hemorrhage does occur, but does not
compress the cord. Subarachnoid hemorrhage is corn-
mon, particularly when the cord is lacerated or contused
or when roots are avulsed.
The secondary changes following spinal injury corn-
prise local or diffuse edema, circulatory disorders, and
TRAUMATIC LESIONS / 457
cord infarction with hemorrhagic necrosis. The forma-
tion of a hematoma in the cord—known as /1emat0mye—
lia—is rarely seen (14).
In autopsies done in cases in which there was only
brief survival following a spinal injury, microscopic
changes in the cord are unusual or absent. In cases in
which survival lasted from one day to three months, the
changes seen in the cord consist of wallerian degenera-
tion, macrophage removal of debris, and astrocytic glio—
sis (28). The neural tissue at the site of the injury is re-
placed with dense gliosis, and there are only limited
regeneration phenomena that have no clinical signifi-
cance. In surviving patients, a delayed myelopathy may
occur after 5 to 10 years, with the formation of cysts in
the cord adjoining the site of an acute traumatic hemor-
rhagic necrosis in the center of the cord or at a distance
from the necrotic site (28). In paraplegia, such as that
caused by thoracolumbar injury, such cysts (p0sttrcm—
matic syringomyelia) may develop, particularly in the
cervical region (29,30).
Cord lesions can be differentiated into complete le-
sions and various types of incomplete lesions.
Complete Cord Lesions
In the acute stage of complete cord lesions there exists
a total ﬂaccid paralysis with full loss of tendon reﬂexes
and sensibility below the level of the injury. The cremas—
teric, sphincter ani, and bulbocavernosus reﬂexes may
persist for some time after the injury, then disappear.
The plantar ﬂexion response is often absent or takes the
form of a ﬂexor variant with a prolonged interval be-
tween the stimulus and the response. Alternatively, it
may persist for a few hours after the injury or reappear
after one or more days, usually only to disappear again,
giving way to an extensor plantar response.
The neurologic deficit in complete cord lesions is de-
termined by the level of the lesion.
C1 to C4
With cord lesions at the C1 to C4 level, the diaphragm
is paralyzed as a result ofinterruption of the segmental
innervation of the phrenic nerve. Because all respiratory
muscles below the transection are also paralyzed, lesions
at this level will lead to death within a short time unless
artificial respiration is applied immediately. With mod-
em management regimes, patients with such lesions can
survive for a considerable time and even breathe sponta-
neously during part of the day with the use of their re-
maining auxiliary respiratory muscles: the trapezius,
sternocleidomastoid, and platysma. They may also be
able to move about in a specially adapted, electrically
driven wheelchair. As a rule, however, the life expec-

458 / CHAPTER 22
tancy of patients with such very high tetiaplegic injuries
is greatly shortened.
Below C4
In the acute stage of injuries below the C4 level, dia-
phragm function is usually impaired but may recover.
The arms of the patient are paralyzed and the shoulders
are drawn up by the action of the levator scapulae and
trapezius muscles. The neck and a small area ofthe ante-
rior aspect of the upper arm have normal sensation; the
rest of the body has a complete loss of sensibility.
Below C5
Patients with lesions below C5 may also need artificial
respiration. In such injuries, the shoulders are elevated,
the arms abducted, and the forearms ﬂexed owing to
uninhibited action of the deltoid, biceps, and brachialis
muscles. Contractures of the elbow easily develop, and
the forearms should thus be kept in extension and the
aims in abduction.
Below C6
With injuries below C6, there is usually sufficient respi-
ratory function for spontaneous breathing; tracheos—
tomy and artificial ventilation are only rarely indicated.
The hands show radial deviation, owing to the action of
the extensor carpi radialis muscles, but are paralyzed.
Below C7
The hand and finger extensors and ﬂexors are func-
tional in the case of injuries below the C7 vertebra, but
the interossei and some opposing muscles are greatly re-
duced in power. This usually results in a claw hand.
Most of these patients are able to write, to feed them-
selves, to type, and, after adequate training, to sit in a
wheelchair with good balance, and can even take up
wheelchair—bound athletic activities.
Thoracic Level
The lower a transverse lesion is localized, the greater
the number of intercostal muscles that function nor-
mally. Patients with complete cord lesions above T5
have, especially initially, impairment of vasomotor con-
trol, which results in postural hypotension when they
move fro1n a horizontal to an upright position (10). In
patients with complete cord lesions below T6, some of
the abdominal muscles may retain intact function.
Epiconus and Conns
Patients with epiconal and conal injuries may have a
paralysis of the legs of the upper or of the lower 1notor—
neuron type. Initially, they usually have urinary reten-
tion. Ultimately, plantar extensor responses and spastic-
ity may develop when the cord lesion supervenes.
Incomplete Lesions of the Cervical Cord
There are various types of incomplete cervical cord
lesions. The various clinical syndromes appear to be in—l
teirelated and extensions of one another. They are not
due to different mechanisms but represent a progression
in the magnitude of the applied forces with increasing
severity of injury (32). A root syndrome is the least seri-
ous clinical definable pattern. With greater force a cen-
tral cord syndrome results, followed by the anterior cord
syndrome, and finally a complete syndrome. Oblique
forces can produce Brown—Sequard syndromes. Varia-
tions in clinical syndromes are caused by the magnitude
and direction of the applied force of injury.
Anterior Cord Syndrome
The anterior cord syndrome (l4,26,3 1) is character-
ized by immediate complete paralysis with hypesthesia
and hypalgesia below the level of the injury, but with
preservation of the touch, motion, position, and vibra-
tion senses. The syndrome is most often seen in hyper-
ﬂexion injuries of the cervical spine and also occasion-
ally in thoracic injuries.
Central Cord Syndrome
The central cord syndrome (31) is characterized by
disproportionally greater motor impairment of the up-
per than of the lower extremities. There may be bladder
dysfunction and varying degrees of sensory loss. In
milder variants of the syndrome, paresis of the arms or
hands is combined with some weakness of the legs; in
severe variants, the arms or hands are paralyzed and the
legs are paretic (14). In patients with the latter type there
may be sensory loss involving all modalities, and urine
retention is always present. This form ofthe syndrome is
predominantly seen in hyperextension injuries but may
also occur in hyperﬂexion injuries (14).
Several hypotheses have been put forward to explain
the predominant localization of lesions in the central
part of the cord, including some based on the relatively
loose texture and rich vascularization of the central cord
region that allows the extension of edema and hemor-
rhage along the central canal in a longitudinal direction.
Other hypotheses attach significance to a relative vascu-

lar insufficiency in the terminal area of the anteiior spi-
nal artery. The discrepancy in motor impairment of the
arms and legs seen with central cord lesions has been
explained by Schneider et al. as being due to the somato—
topic division of the lateral and posterior columns of the
cord (31). The central areas of the lateral pyramidal
tracts, spinothalamic tracts, and posterior columns are
supposed to contain supranuclear fibers for the neck and
arms; the lateral parts are supposed to contain fibers for
the thoracic, lumbar, and sacral segments. This explains
why a central cord lesion primarily affects the upper part
of the body. This theory assumes that the motor impair-
ment of the arms that is seen in the central cord syn-
drome is due to supranuclear lesion; in our experience,
however, this may also be the result of involvement of
the anterior horns (14).
Brown—Sequard Syndrome
The Brown—Sequard syndrome indicates a lesion of
one lateral half of the spinal cord. It is characterized by
an ipsilateral paresis and loss of proprioceptive sensa-
tion, with sensory ataxia below the level of the lesion,
and contralateral loss of pain and temperature sensation.
The syndrome is rarely encountered in its pure form or
with blunt injuries, yet it is nevertheless common
enough to classify many cord lesions as producing the
Brown—Sequard syndrome if there is an asymmetric pare-
sis of the lower extremities with analgesia or hypalgesia
on the least paretic side (10,14). A slowly progressive
Brown—Sequard syndrome suggests spinal cord compres-
sion on one side, such as by a prolapsed intervertebral
disc (14).
Contusio Cervicalis Posterior
A reversible traumatic syndrome of the cord, charac-
terized by pain, tingling, and hyperesthesia in a multiseg—
mental area of the neck, arms, and hands, but sometimes
also in the trunk, has been designated contzisio cervicalis
posterior (14). It is a common, mild, and reversible cord
syndrome that may occur in combination with a mild
paresis of the arms and hands and slight dysfunction of
the long tracts as an intermediate condition between the
more severe and the milder types of central cord injury.
Other Lesions
Besides the patterns described above, there are other,
less common patterns of cervical cord lesions, such as
the bulbar cervical dissociation pattern, the onionskin
pattern, and other patterns that are more difficult to cate-
gorize (14,31,32). Additionally, one or more cervical
TRAUMATIC LESIONS / 459
roots are often involved in cervical spine injuries, particu-
larly in cases of unilateral or bilateral facet interlocking.
hicomplete Lesions of the Thoracic Cord
More than 85 percent of patients with a thoracic in-
jury and a cord lesion have a complete cord lesion
(11,33,34,35). Fewer than 10 percent of these patients
show any further improvement, particularly of a sensoiy
nature (1 1). Incomplete lesions commonly produce the
anterior cord syndrome.
Incomplete Lesions of the Conus and Cauda
Patients with fracture dislocations or burst fractureVof
the thoracolumbar area may have cord or cauda equinav
lesions. About 60 percent of these patients have com-
plete lesions and another 40 percent incomplete lesions.
In the acute state following an incomplete lesion, it is
very difficult to assess whether part of the conus or some
roots have escaped damage. The fracture—dislocation in-
jury (Fig. 13) in particular yields a high proportion of
complete lesions (11,34,35).
The wide variation in the neurologic picture encoun-
tered in thoracolumbar lesions is mainly owing to a valia-
tion in the exact vertebral level of the conus and cauda.
Moreover, the form and capacity of the vertebral canal
may vary widely. The common denominator in patients
with thoracolumbar injuries and involvement of the
cord, cauda, or both is the presence of bone in the spinal
canal.
In injuries of the lumbar and lumbosacral spine, the
neurologic symptoms result from lesions of the cauda
equina. These root lesions may heal partially or com-
pletely, even after many months. The recovery processes
are comparable to those seen in peripheral nerve inju-
rres.
Progressive Cord Lesions
Neurologic symptomatology is usually maximal di-
rectly after injury to the spinal cord and may then persist
or gradually disappear, either completely or partly.
Sometimes, however, neurologic symptoms develop or
increase in severity at some time after the original injury.
This usually happens within the first few days, but it may
start months or even years after the accident. The most
common manifestation of such progressive injury is an
elevation in the level of the lesion, usually by one or two
vertebral segments, occurring within the first few days
after the accident (36). This is because of cord swelling
and is transient. Early progressive cord lesions may also
be attributed to a missed radiologic diagnosis. The fail-
ure to recognize a spinal injury often results from an

460 / CHAPTER 22
incomplete radiographic examination, particularly of
the cervicothoracic junction.
Inexpert transport has been reported to be responsible
for progressive cord lesions (10); as has excessive skull
traction during the hospital stay (14). Imperfect intuba—
tion, especially in unstable hyperﬂexion and hyperexten—
sion injuries of the cervical spine, may cause disastrous
neurologic deterioration. The same applies to surgical
intervention, particularly in cases with severe incom-
plete cord lesions, or in which there occurs a marked
narrowing of the spinal canal, such as during an opera-
tive attempt to reduce facet interlocking. A traumatic
disc prolapse or the very rare extradural hematoma may
also be responsible for early progressive cord lesions
(14,31).
Most late progressive cord lesions are owing to a per-
sistent deformation of the spinal canal. The lesion occurs
in that segment of the cord that rides over the backward-
projecting upper margin of a body of a lower vertebra, as
in badly healed cervical compression—fracture disloca-
tions with major kyphotic angulation (25). Another
cause for a late progressive cord lesion may be a pro-
lapsed disc or a non—united fractured odontoid process
with atlantoaxial instability and intermittentpinching of
the cord between the superoposterior border of the body
of the axis and the posterior arch ofthe atlas (14). In 1 to
2 percent of patients with paraplegia, the cause of a de-
layed cord lesion is the development of an intramedul—
lary cyst (29,30). In such posttraumatic syringomyelia,
the symptoms are usually loss of pain and temperature
sensation over several segments of the cord rostral to the
i original injury site. In thoracolumbar spinal injuries the
cyst may extend to the cervical region. Initially, most of
the symptoms and signs created by the cyst are unilat-
eral, but become bilateral later. The pathogenesis of
posttraumatic intramedullary cysts remains controver-
sial, although abnormal pulsations of cerebrospinal ﬂuid
(CSF) acting on the central canal are considered to be of
considerable importance in their origin (29,30).
Frankel's Classification
Frankel's system of classification (l4,37) enables one
to compare more easily the neurologic state of a spinal-
cord—injured patient on admission and on discharge. In
this classification, there are five categories:
A. Complete. There is a complete loss ofmotor and sen-
sory function below the level of the lesion.
B. Sensory only. Motor paralysis is complete below the
level of the lesion, but some sensation is present.
C. Motor useless. Some motor power is present below
the level of the lesion but is of no practical use to the
patient.
D. Motor useful. There is useful motor power below the
level of the lesion. The patient can move his or her
lower limbs and many patients can walk with or
without support.
E. Recovery. The patient is free of neurologic symp-
toms such as weakness, sensory loss, or sphincter dis-
turbances; however, reﬂexes may be abnormal.
The grading in Frankel's classiﬁcation is both func-
tional and categorical, so that movement from one grade
to another is truly significant in terms of practical out-
come. One problem of the classification is created by the
terms useful and useless, and also by the fact that too
many of the incomplete lesions fall into the D category.
Formal observer—variation studies regarding this classifi-
cation have not thus far been carried out.
PROGNOSIS
Mortality
Mortality following a spinal cord lesion depends on
the level and severity of the lesion, the presence of severe
associated injuries, and the age and premorbid medical
condition of the patient (10,14,38). About 20 percent of
persons involved in a fatal traffic accident have cervical
spine injuries, commonly at the craniocervical junction
(31). These injuries are often not diagnosed as such be-
cause the time—consuming and difficult autopsy of this
area is not routinely performed. The total number of
persons with paraplegic spinal injuries subjected to au-
topsy is also relatively limited because currently most of
these patients survive. Moreover, during routine autopsy
it is unusual to preserve both the spine and medulla (39).
In cases with a short survival, cervical cord injuries
constitute the largest group of cord injuries. The main
causes of early death are pulmonary embolism, other
pulmonary complications, cardiorespiratory failure due
to bulbar involvement, and head injuries or multiple le-
sions elsewhere in the body (38,39). In thoracic and tho-
racolumbar spinal fractures, death is usually due to mas-
sive trauma with complete disruption of the spine and
spinal cord (11,39), and major abdominal and thoracic
injuries.
The most common causes of death in patients with a
survival of from three months to five years are respira-
tory complications and pulmonary embolism, while in
those surviving more than five years urogenital compli-
cations and hypertension are the major causes of death.
Less common causes of delayed mortality are cere-
brovascular accidents, bladder carcinoma, and suicide
(10,38,39).
Recovery of Function in Survivors
An initially complete cord lesion may be fully revers-
ible if it is owing to spinal shock (10). Moreover, a combi-

rratiorr of spinal shock and partial destruction ofthe cord
will progress to partial recovery. In cases of complete
cord destruction, however, the lesion is irreversible.
In a series of 97 cases of cervical cord injury with corn-
plete loss of neurologic function below the level of injury
on the admission examination shortly after the i1rjury—
causing accident, six patients recovered partially within
the first 24 hours. Among the remaining 91 patients, the
cord lesion was fully irreversible in 85. In six patients
there was complete and lasting motor paralysis, but
some return of sensation which was, however, of no use
to the patient (Frankel's grade B) (36). Frankel (36) and
Young and Dexter (40) report that about 5 to 10 percent
of patients who have a complete cord lesion on an initial
examination a few hours after the i1rjury—causi1rg acci-
dent may show some return of sensory function within
the first 24 hours posttrauma, occasionally followed by
some motor recovery.
Patients with complete motor paralysis but some serr-
sory preseryation, as in the anterior cord syndrome, may
regain partial motor control (14,26,37,40). Motor power
in the legs of these patients may return to a useful level,
permitting them to move their lower limbs and, in some
cases and after some years, even to walk with mechanical
aids. In an initially incomplete motor paralysis, such as
occurs in the Brow1r—Sequard syndrome and in central
ceryical cord lesions, recovery varies but is usually quite
satisfactory with regard to the lower extremities and
bladder control (14). Frankel et al. (37) and Young and
Dexter (40) noted marked improvement in such patients
(groups C and D in Frankel's classification).
In the ceryical central cord syndrome, the prognosis is
generally favorable with regard to bladder control and
the ability to walk (14). Here too, the degree of recovery
depends upon the amount of functional damage as op-
posed to structural damage. Motor power in the lower
extremities returns first, bladder function next, and fi-
nally movement irr the upper extremities. In a personal
series of more than 100 patients with an initial ceryical
central cord lesion, all were ultimately able to walk witlr—
out crutches (14). Finger movement is the very last mo-
tor function to recover—ofte1r only partially—i1r such
patients. The chances of ultimate complete recovery irr-
crease if the patient is young and if there is initially a
paresis rather than paralysis. Some recovery within the
first few days after the accident is a favorable sign.
In the Brow1r—Sequard syndrome, there is no fixed se-
quence irr the process of recovery, and no correlation
between onset of motor and sensory recovery can be
found. On the basis of our experience with 35 patients,
we have concluded that the prognosis cannot be reliably
predicted. Some patients recover completely, whereas
others have a marked persisting neurologic deficit (14).
In contusio cervicalis posterior, the prognosis is al-
most always favorable. Irr exceptional cases, tingling in
the fingers or hands may persist for more than one
—TRAUMATIC LESIONS / 461
month. The prognosis in the case ofroot lesions is favor-
able, provided that facet interlocking, if present, is re-
duced.
Only 10 percent of patients with complete thoraco—
lumbar conus and cauda lesions show some improve-
ment. This improvement commonly begins within the
first 12 hours. The majority of patients with incomplete
lesions improve, often over more than one Frankel
grade, and many patients in this group even have a com-
plete recovery (34,37). The motor deficit, which is of the
ﬂaccid type initially, may ultimately be partly of the up-
per motor—1reuro1r and partly of the lower motor—1reuro1r
type. It is very difficult to predict whether spasticity will
appear later in these patients.
TREATMENT
General
The successful treatment of paraplegic patients de-
pends on rigorous interdisciplinary cooperation between
the various specialists who treat them (10). This is an
argument for admitting most spi1ral—cord—i1rjured pa-
tients irrto a spinal unit with intensive care facilities ei-
ther directly or within the first week after injury. Disap-
pointing results of treatment are often due to a lack of
balance between various aspects of the treatment. An
example of this is the patient with a complete ceryical
cord lesion in whom orthopedic measures for the injury
of the ceryical spine are taken, but in whom the preve1r—
tion of pulmonary complications and pressure sores is
neglected. In such a case, lifesaving procedures have the
highest priority, and measures to prevent pressure sores,
urinary infection, and pulmonary collapse or infection
should be undertaken immediately after the accident,
since they are more critical than orthopedic measures for
the spine injury. The priorities of different measures vary
from one case to another, depending on the severity and
extent of the spinal damage, associated injuries, and the
patie1rt's age, pretraumatic illnesses, and habits. In addi-
tion to the possibly life—tlrreate1ri1rg complications of
pressure sores, urinary infections, thrombosis, and pul-
monary complications irr patients with severe cord defi-
cit, other complications irr the first week following injury
in such patients are intestinal ileus and temperature
disregulation.
Pneumatic alter1rati1rg—pressure mattresses fail to pre-
vent pressure sores in paraplegic patients. To prevent the
sores from developing, these patients must be turned
every 2 to 3 hours. This turning has the additional pur-
pose of sustaining respiratory, renal, and intestinal fu1rc—
tion. Plaster casts, hard pillows, and spasm are all patlro—
genetic dangers in the development of pressure sores.
However, even the best—staffed hospitals often have a
shortage of nurses that makes it impossible to turn para-

462 / CHAPTER 22
plegic patients every 2 hours, unless speciﬁc beds such as
the Stryker frame and its derivatives, or the Egerton—
Stoke—Ma1rdeville frame are used (10).
If the patient is incorrectly positioned in bed, contrac-
tures are likely to develop. In a supine tetraplegic patient
the arms should be moderately abducted at the
shoulders, the elbows placed in extension and the hand
joint and fingers placed in the functional position (9, 10).
When the patient lies on his or her side, the lower arm
should be ﬂexed at the elbow joint and rotated outwards
at the shoulder. The upper arm should lie along the
body. The hip joint should be placed in extension and
moderately abducted, the knee joints placed in slight
ﬂexion, and the ankle joints placed at right angles.
In later stages of treatment, it is important that the
patient be educated to take over the task of preventing
pressure sores. Paraplegic patients in wheelchairs should
lift themselves up from their chair cushions for a few
seconds at regular intervals and must learn to turn them-
selves regularly irr bed at night.
Even today the urinary complications of infection and
stone formation are the main causes of death in paraple-
gic patients (9,l2,38). In fact, the prognosis quo ad vitam
in a paraplegic patient lies primarily in the kidney. In the
initial period after the spinal trauma, the bladder will
reﬂect a lower motor—1reuro1r—type injury with inactivity
and the retention of urine. In nonspecialized hospitals,
inﬂatable balloon catheters such as the Foley catheter are
recommended for treating this. However, the disadva1r—
tage of these catheters is that they may lead to the devel-
opment ofurethritis, orchitis, epididymitis, and pressure
sores at the pe1ro—scrotal angle. Urinary infection com-
monly occurs within a few days in an inactive bladder.
With regard to intravenous therapy, Foley catheters may
be temporarily indicated, but the routine use of an irr-
dwelling catheter is no lorrger justified. With the use of
the intermittent catheterization three or four times per
day by well—trai1red nurses or by doctors under aseptic
conditions as strict as those in surgery, it is possible to
maintain a sterile urine in the paralyzed patient for a
period of weeks or months (9, l2, 13). The contents ofthe
bladder should never exceed 500 ml. Acidifyirrg drugs
will bring about the desired acidification of urine and
may help in preventing the formation of stones.
Initially, gastrointestinal atonia is almost always pres-
ent irr paralyzed patients. Vomiting can be treated by the
insertion of a nasogastric tube. Enemas are necessary if
spontaneous evacuation of the bowels does not occur
within three days after a spine injury. After this evacua-
tion, light food may be given combined with mild laxa-
tives, which are administered either orally or rectally at
least once every 48 hours.
In the acute and subacute phase of treatnrent of para-
llyzed patients, a balanced acid—base ratio and electrolyte
values should be guaranteed by repeated blood—gas a1raly—
sis and electrolyte determinations. Continuous nro1ritor—
ing of the central venous pressure is indispensable to cir-
culation surveillance (9). Physiotherapists arrd the
nursing staff should take care of respiratory exercises and
coughing assistance, particularly in tetraplegic patients.
Any retention of bronchopulmonary secretions should
be alleviated with the aid of secretion stimulants. Bro1r—
choscopic aspiration or controlled ventilation may be
necessary to relieve atelectasis (9). Tracheostomy should
preferably be avoided because the loss of speech for the
tetraplegic patient means deprivation of his or her last
means of communication with the environment.
The incidence of deep venous thrombosis and pulmo-
nary embolism irr paralyzed patients can be reduced by
the immediate use of prophylactic anticoagulants, and
particularly by the use of small doses of heparin. The
incidence of thrombosis and embolism can also be de-
creased by regular turrrirrg and intensive physiotherapy
(passive movement) of the patie1rts—measures that
should start on the first day of hospitalization.
In tetraplegic patients, there may be disrupted heat
loss from the body, and air—co1rditio1red wards with a
constant temperature may be necessary to prevent hypo-
or hyperthcrmia (9). The rehabilitation of the paraplegic
patient, in terms of all of the measures employed to re-
store the patie1rt's social and vocational independence, is
beyond the scope of this chapter.
Cervical Spine
The deformation of the cervical spinal canal following
a spinal injury can be corrected by postural reduction,
manual reduction, manual reduction under anesthesia,
skull traction, or open surgical reduction (14).
Postural Reduction
Postural reduction is the method of choice in hyper-
ﬂexion sprains, hyperextension sprains, and anterior at-
lantoaxial dislocations. The kyphotic angulation in hy-
perﬂexiorr sprains can be corrected by retroﬂexion of the
neck over a roll placed in the nape of the neck. The
lordotic angulation in hyperextension sprains can be re-
duced by careful ﬂexiorr of the neck under ﬂuoroscopic
control. Anterior atlantoaxial dislocations can also be
reduced by retroﬂexion of the neck.
Manual Reduction
Manual reduction under anesthesia with traction in
the long axis of the spine under ﬂuoroscopic control but
without manipulation is, according to many European

authors, the method of choice in cases of recent inter-
locking (14).
Traction
Traction along the axis of the cervical spine has been
used for centuries to reduce dislocations and to realign
the spinal canal in fracture dislocations. Skull traction by
means of tongs was introduced by Crutchfield in 1933,
and Various modifications of the tong method have been
developed in recent decades (14). In cases of facet inter-
locking, many authors use weights of 15 to 50 kgs, with
radiographic control every 15 to 60 minutes to check for
reduction or abnormal diastasis between vertebrae. The
minimum and maximum weight can be varied accord-
ing to the affected level of the cervical spine. Skull trac-
tion with weights of 3 to 6 kgs may support realignment
of the spinal canal in cases of compressive hyperexten—
sion fracture dislocation, and, to a lesser degree, corn-
pressive hyperﬂexion injuries such as the teardrop frac-
ture.
In the case of facet interlocking, surgical reduction can
be obtained through a posterior approach levering the
displaced facets into place (14). Sometimes, partial re-
moval of a superior articular process is necessary. In
more recent years, anterior approaches to the reduction
of interlocked facets have been developed (41,42). The
affected disc is excised and reduction is facilitated by
increasing distraction, with the vertebral bodies sepa-
rated by the insertion of a lever and the dislocated verte-
bra being digitally pressed backwards (42).
Nonsurgical Stabilization
Cervical fractures heal by the endosteal and periosteal
formation of new bone. Healing occurs slowly, and it
may take years before radiographs no longer show any
change in the bony structure. Sometimes, fibrous heal-
ing is the final result, particularly with fractures of the
odontoid process. In ruptured ligaments and discs, fi-
brous tissue and sometimes even bone is formed. The
conservative management of cervical spine injuries with
bed rest for periods of weeks or months is universally
used and was in the past advocated by numerous au-
thors, including Guttrnann (10), and Braakman and
Penning (14). Late instability was rare. Instability was
particularly observed following hyperﬂexion cornpres—
sion injuries, such as the teardrop fracture, and hyper-
ﬂexion sprains. However, during the last decade conser-
vative management with bed rest has been more and
more replaced by Halo—vest immobilization or surgical
stabilization. Lind reported that the healing rate in his
series of 83 patients with unstable injuries of the cervical
spine was high (90 percent), with minor complications
TRAUMATIC LESIONS 463
(44). The Halo—vest is simple to use and makes early
ambulation possible. Residual symptoms are stiffness
and pain at motion in the neck, which might be de-
creased by reduction of the length of the treatment pe-
riod. According to this author and many others, particu-
larly in Europe, Halo—vest treatment should be used as
the primary treatment of all cooperative patients with
unstable cervical spine injuries.
Surgical Stabilization
Primary surgical stabilization of cervical spine injuries
is advocated by many authors, initially particularly in
the United States. In 1959, Forsyth and associates stated:
"The general routine of skeletal traction, internal fixa-
tion and spine fusion constitutes a method of treatment
that needs to be varied but slightly in order to include a
large percentage of all serious injuries of the cervical
spine"(45).
The main argument for the surgical approach is the
occasional recurrence ofdislocation or of kyphotic angu-
lation after distractive and compressive hyperﬂexion in-
juries and conservative management. Another is the
long period of bed rest required with conservative inan-
agement, an approach that may be too expensive for the
patient and may hamper rehabilitation.
The surgical procedure may be performed through a
posterior or anterior approach to the spine (14,41 -43),
depending upon the level and the type of vertebral injury
and the preference and experience of the surgeon. In the
posterior approach, wiring of the spinous processes or
arches, or plating of the arches is usually done, followed
by bone grafting. This procedure is reliable and will in
almost all cases result in fusion, provided that the postop-
erative period of external irnrnobilization—either by bed
rest followed with a snugly fitting brace, or by a Halo-
vest—lasts at least 10 to 13 weeks.
In the past 30 years, anterior spinal fusion has become
a well accepted procedure in the surgical management of
cervical spine injuries (14,24,42). The anterior approach
has several advantages over the posterior approach. Dur-
ing the operation, the patient can remain in the supine
position, which is an advantage when there are maxillo—
facial injuries or injuries of the chest or limbs. Blood loss
is minimized, and it is easier to keep the spine immobile
during the positioning on the operation table and during
the operative procedure itself. The postoperative irnrno—
bilization of the patient is also somewhat shortened.
However, there are more disappointing long—term results
due to an imperfect operative technique with the ante-
rior approach than with the posterior approach with wir-
ing and grafting.
Once ambulation begins, either after the surgical treat-
ment or conservative management of an injury of the

464 / CHAPTER 22
cervical spine, external fixation of the spine is commonly
necessary. Currently, Halo-jackets or vests are corn-
rnorrly used instead of braces.
Thoracic Spine
Most injuries between T1 and T10 are quite stable,
due to splinting by the rib cage and the sternum. Conse-
quently rnost of them do not need internal fixation and
can be treated with external ortlrotic support. Arnbula-
tion is allowed within a few weeks. In more severe, com-
plex fracture dislocations, open reduction may be re-
quired, arrd internal fixation and spinal fusion or
lorrg-terrn bed—rest immobilization is necessary to
achieve stability.
Many patients with paraplegia due to an injury of the
thoracic spine are anoxic and hypercarbic as a result of
multiple associated injuries (9) and require intensive
care.
Thoracolumbar Spine
The treatment of injuries of the thoracolumbar spine
and lumbar spine has changed markedly during the last
decade. The aim of successful treatment is to achieve a
stable pain—free spine with minimal deformity and rnaxi-
mum neurological recovery. The central object of corr-
cem is the spinal cord and cauda. The means of aclriev—
ing this goal remain controversial. Before 1980 there
were, in addition to the advocates of the conservative
management of thoracolumbar spine injuries (9-11),
those who preferred elective surgical management only
in cases with incomplete or progressive cord lesions, and
others who advocated early laminectomy to "decorn-
press the cord or cauda," with subsequent surgical reduc-
tion and internal fixation.
Guttmann (10), Bedbrook (1 1), and Frankel and col-
leagues (37) have advocated a conservative regimen of
postural reduction. Normal lumbar lordosis is restored
and maintained by the use of lumbar pillows or sorbo-
packs. These authors claim that postural reductiorr can
be achieved in more than 70 percent of cases treated in
this way and that, even in thoracolumbar ﬂexion—rota-
tiorr injuries that cannot be reduced, adequate conserva-
tive management prevents furtlrer displacement. Corn-
puted tomographic follow-up studies, however, have
revealed that, particularly in burst fractures, postural re-
duction usually does not realign the broken—off part of
the vertebral body that is displaced into the spinal canal:
the narrowing of the spinal canal persists. Another disad-
vantage of this method is that prolonged recumbency
does not guarantee stability. It is claimed, however, that
with such management late instability occurs in less than
1 percent of injuries (11). The method requires highly
motivated, vigilant, and expert nursing in specialized spi-
nal cord units. With the decreasing availability of trained
nurses, tilting-and-tuming frames such as the Egerton-
Stoke-Marrdeville, the Stryker, and various other types
of frames have come into use.
Other authors have preferred conservative rna1rage-
ment in patients with complete cord lesions but have
held that there is a role for surgery in patients with dislo-
cations that carr only be poorly reduced by postural
methods, and for patients with incomplete neurologic
lesions. The procedure advocated in these cases is open
reduction and internal fixation by bone.
Many neurosurgeons and also some orthopedic sur-
geons lrave advocated laminectomy in the expectation
that this kind of surgical decompression might enhance
neurological recovery. Follow-up reports, however, have
shown that laminectomy leads to increased patient rnor-
bidity and increased instability, and also fails to decorn-
press the spinal cord, mainly because the extradural
compression is situated anterior to the thecal sac. Re-
moval of a few arches results in an increase of instability
with increased pain over the long term (34).
Currently, most surgeons believe that neurological re-
covery can best be achieved by the restoration of alig1r-
ment of the spine through open reduction and internal
fixation, facilitating rapid restoration of the spinal alig1r—
ment and reducing nursing problems (46-50). Wire
loops, metallic plates, springs, compression and distrac-
tion rods, arrd anterior or posterior bone grafts may be
used as an internal splint. However, spinal instrumenta-
tion alone does not guarantee consistent and effective
decompression of the cord, because loose fragments may
remain in the spinal canal and progressive kyphosis is
not rare. Satisfactory decompression requires direct re-
moval of bony and disc elements from the spinal canal.
This can be achieved by a posterolateral approach
through the pedicle, removing free pieces of bone or disc
or tamping the bone anteriorly out of the canal back into
the fractured body (50). Subsequently, stabilization can
be obtained using a Harrington rod system (46-48), a
fixateur interne (51), the Zielke apparatus (52), or the
Luque rods (53). Bony posterior fusion is generally rec-
ommended. Others prefer a lateral extracavity tra1rstlro-
racic or retroperitoneal approach to the spinal canal (54).
The advantage is the direct approach to the anterior part
of the spinal canal; the disadvantages are that this ap-
proach causes more blood loss and is a major procedure
that may be too radical for rnultitraurnatized patients
with severe cord deficit.
These procedures permit many patients to be ambu-
lated within a few days after the operation. They are the
most effective methods of achieving reduction, stability,
decompression, and early mobilization in cases of thora-
colurnbar and lumbospinal injuries. Theoretically, it
seems likely that this decompression of the neural ele-
ments provides improved and more rapid neurological
recovery, but thus far this has not been proven (49,55). j

There are no major differences in the degree and speed of
neurological recovery in series of patients subjected to
early surgical decompression and stabilization and that
in series of patients subjected to conservative rna1rage-
ment. The main value of the surgical approach in the
early management of injuries of the thoracolumbar
spine with neurological deficit is in immediate stabiliza-
tion, wlriclr diminishes pain, facilitates nursing care, and
allows more rapid mobilization. This results in a shorter
stay in hospital and earlier active rehabilitation (49).
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J elsma RK, Kirsch PT, J elsma LF, Ramsey WC, Rice JF. Surgical

CHAPTER 23
Peripheral Nerve Injury
Barton A. Brown
I11cide11ce, 467
Etiology, 467
Pathology, 467
Symptoms, 468
Signs, 469
Natural History, 469
Diagnostic Tests, 469
INCIDENCE
Peripheral nerve injuries continue to be challenging
problems despite recent technical advances. Peaks of in-
terest in peripheral nerve problems occur with wars, be-
cause large numbers of cases are then concentrated for
study. However, civilian injuries in home, industry, and
recreational accidents provide another large group for
study and treatment.
Accurate figures of the incidence of peripheral nerve
injuries in civilian practice are difficult to establish be-
cause such lesions are treated by a number of specialists.
Treatment may be provided by a general, orthopedic,
plastic, hand, or neurologic surgeon. The particular spe-
cialty of the treating surgeon is unimportant as long as he
or she is well versed in the neuroanatomic and neuro-
physiologic principles and surgical techniques pertaining
to peripheral nerve injuries.
Of 1,123 admissions to an urban neurosurgical service
in a 12-month period, 45 were peripheral nerve injuries,
constituting 4 percent of admissions. In a given neurosur-
gical practice, the number might be considerably greater,
depending upon the physician's interest in such lesions.
The incidence of involvement of a specific nerve, as
recorded in a general neurosurgical practice, is illus-
trated in Table 1.
B. A. Brown: San Francisco, California 94118.
Principles 0j’Neur0surgery,
edited by Robert G. Grossman. Rosenber © 1991.
Published by Raven Press, Ltd., New Yor .
I11dicatio11s for Surgery, 470
Preoperative Management, 470
OperativeMa11agen1e11t,471
Neurolysis, 471
Nerve Suture, 471
Outcome, 472
References, 472
ETIOLOGY
Causes of nerve injury can be conveniently divided
into penetrating and nonpenetrating types. Penetrating
injuries usually result in partial or complete discontinu-
ity of the nerve. Examples include gunshot wounds, frac-
tures, and lacerations by glass or metal. Exceptions
would be injection palsies (1) and blast injuries from
gunshot wounds in which continuity is preserved despite
penetration.
Nonpenetrating injuries may be contusions, as from a
direct blow over the nerve; compressions, as seen with
sleep palsies, entrapments (2), compartment syndromes,
hematomas, tourniquet palsies, casts, and obstetric pal-
sies; friction injury, as in tardy ulnar palsy and certain
occupational palsies; or stretch injuries.
PATHOLOGY
On a cross section, a peripheral nerve is composed of a
multiplicity of axons surrounded by an endoneurial col-
lagenous tube. Varying numbers of axons and their in-
vesting sheaths are grouped together in fascicles by a
loose connective tissue called the perineurium. Groups
of such fascicles are bound into the entity of the mixed
peripheral nerve by the epineurium, the thickened exter-
nal layer of which constitutes the external nerve sheath.
The blood supply to a peripheral nerve has a linear
467

CHAPTER 23
TABLE 1. Frequency of injury
Nerve Number Percentage
Axillary 16 1.6%
Brachial plexus 86 8.5%
Dorsal scapular 2
Femoral 18 1 .8%
Gluteal 1
Greater auricular 1
Greater occipital 1
Hypoglossal 2
llioinguinal 1
Lateral femoral cutaneous 8
Long thoracic 11 1.1%
Lumbosacral plexus 8
Median (carpal tunnel 111) 222 22.0%
Musculocutaneous 8
Peroneal 73 7.3%
Polyneuropathy 10 1.0%
Radial 1 06 10.5%
Saphenous 9
Sciatic 67 6.6%
Suprascapular 10 1 .0%
Sural 2
Spinal accessory 13 1 .3%
Tibial 13 1 .3%
Ulnar 317 31 .5%
Total 1,005
distribution, with major feeding vessels entering the
nerve at different levels and distributing branches longi-
tudinally up and down the course of the nerve. Smaller
branches penetrate to the innermost portions of the
nerve.
The mixed peripheral nerve is made up of both motor
and sensory fibers, the latter subserving various types of
function. Within the nerve, the axons are generally
grouped according to anatomic distribution rather than
function. The intraneural plexuses change continually
through the course of the nerve, and cross sections of a
peripheral nerve one or more centimeters apart will
show a different pattern of fascicular arrangement (3).
Branches usually leave the main nerve trunk at an acute
angle, a factor of some importance in surgical treatment.
Sunderland has pointed out that the axonal content,
as opposed to the connective tissue content, of a periph-
eral nerve at any point in its course is Variable but that it
is usually 50 percent or less and may be as low as 12
percent, as in the sciatic nerve at the sciatic notch (3).
Nerve tissues are subject to the same types of pathol-
ogy as other body tissues. They are affected by infectious,
metabolic, vascular, and traumatic lesions. In the last
category, three general types of nerve injury are recog-
nized:
1. Axonapraxia, in which the nerve loses its conductiv-
ity without any actual disruption of the axons or
nerve sheath and which may result from contusion,
entrapment, hcmatoma, or other pressure—related
phenomena in which there is no laceration of the
nerve substance;
Axonotmesis, in which the insult is severe enough to
cause Wallerian degeneration but insufficient to
disrupt the connective tissue framework of the nerve;
and
3. Neurotmesis, in which both axonal and connective
tissue elements of the nerve are disrupted.
Chronic compression, contusion, stretching, injec-
tion, or laceration of a nerve may cause vascular and
connective tissue damage and may cause edema and
hemorrhage in and about the nerve as well as axonal
damage. The result is external and internal ﬁbrosis of the
nerve.
An injury of sufficient severity, whether caused by
contusion, compression, laceration, or injection, will
cause degeneration of the axons and their myelin sheath
distal to the site of trauma. There is also retrograde de-
generation, probably not exceeding one or two nodes of
Ranvier. The distal degeneration, fragmentation, and
phagocytosis of the axon and myelin sheath are termed
Wallerian degeneration. This degeneration occurs over a
period of approximately two to three weeks following
injury; at the end of that time, only the empty connective
tissue framework of the distal portion of the peripheral
nerve remains.
During this time an intracellular reaction is occurring
in the anterior horn cells of the spinal cord that corre-
spond to the injured axons. These cell bodies undergo a
reaction of varying severity, depending upon the extent
of injury to the peripheral nerve and the proximity of the
injury to the anterior horn cell. If an affected anterior
horn cell survives, it begins to produce axoplasm; thus,
growth of the axon from the proximal site of discontinu-
ity occurs. The regenerative process of the anterior horn
cell takes approximately three weeks before axoplasmic
flow will proceed from the site of injury. At the proximal
end of the divided nerve, axonal regrowth in combina-
tion with fibrosis will create a so—called "neuroma." The
distal end of the divided nerve will develop a bulbous
enlargement of fibrous tissue, the "glioma." A partially
divided nerve or one with chronic ﬁbrosis will develop a
"neuroma in continuity."
The external nerve sheath has limited elasticity, and
increase in tissue elements within the nerve, either from
hemorrhage or ﬁbrosis, can result in compression of ax-
ons. Thus, internal as well as external fibrosis may con-
tribute to nerve dysfunction.
Severe stretch injuries cause diffuse axonal and con-
nective tissue disruption along the trunks or plexuses
and seldom lend themselves to specific surgical treat-
ment.
SYMPTOMS
Peripheral nerve injury results in motor loss, sensory
loss, or both, in a distribution appropriate to the in-

volved nerve. Symptoms are paresthesias, weakness, and
pain, either intermittent or constant.
Patients will describe sensory loss in a general area and
motor loss in terms of the activities that cause them diffi-
culty. A patient with carpal tunnel syndrome, for exam-
ple, may say that "the entire hand gets numb," not just
the median nerve distribution. A patient with an ulnar
palsy will often complain of difficulty manipulating
coins and of catching the fifth finger on a pocket. A simi-
lar difficulty with manipulation of coins may be mani-
fest in a median rreuropathy, but in this case the diffi-
culty will be secorrdary to the loss of sensation in thumb,
index, and long fingers rather than to speciﬁc loss of
dexterity, as in ulnar palsy.
Pain may be a significant symptom in certain nerve
injuries, particularly brachial plexus injuries, and in par-
tial median nerve lesions with resultant causalgia. Some-
limes pain is caused by muscular imbalance rather than
by direct insult to the nerve, as in spinal accessory nerve
palsy, with its loss of trapezius function and resultant
shoulder girdle imbalance.
SIGNS
Signs are elicited by a careful neurologic examination
with special study of the ﬁeld of the injured peripheral
nerve. This examination involves testing motor power,
sensation, reﬂexes, and autonomic function and looking
for atrophy, fasciculations, and visible or palpable ab1ror—
malities on the nerve trunks. Any sign of motor deﬁcit,
such as weakness of abduction and adduction of the
fingers in an ulnar lesion, or loss of dorsiﬂexion of the
foot in a peroneal palsy, should be carefully sought. Sen-
sory loss appropriate to the injured nerve is tested for
with pin, touch, and, especially in the hand, two—point
discrimination. It is helpful to have a reference text for
review of speciﬁc muscle innervation and sensory pat-
terns and to have motor and sensory examination charts
for recording the ﬁndings, as certain lesions are i1rfre—
quently seen (4,5).
If the lesion is two or three weeks old, atrophy and
fasciculations ofthe muscles in the involved field may be
observed. In the limbs, the muscles should be accurately
measured as well, as described. There may be evidence of
autonomic dysfunction manifested by altered skin tem-
perature or color. Reﬂex changes will conform to the
appropriate nerve distribution.
Local signs should also be sought, such as tenderness
of a nerve trunk or Tinel's sign with percussion over the
nerve. Palpation of nerve trunks may reveal such lesions
as Struther's ligament, nerve tumor, or neuroma.
The examiner must be aware of trick movements and
secondary dysfunctions, as in radial nerve palsy in which
the wrist drop prevents satisfactory function of the ul1rar—
innervated small hand muscles. Here the examiner must
PERIPHERAL NERVE INJURY / 469
hold the wrist in extension or place the hand on a ﬂat
surface in order to get a more accurate evaluation of
ulnar function in the presence of radial nerve palsy.
NATURAL HISTORY
It is important that an accurate initial examination be
obtained so that recovery or lack thereof can be accu-
rately monitored. Mild compressive nerve lesions such
as sleep palsies will show a rapid recovery, with motor
and sensory function returning within a few minutes or a
few days. More severe lesions in which the continuity of
the nerve is intact may take several weeks to recover.
These lesions would fall into the category of axona—
praxia, however, and spontaneous resolution is likely.
If axonotmesis has occurred with Wallerian degenera-
tion but with preservation of the endoneurial tubes so
that each axon is directed back to the e1rd—organ it origi-
nally subserved, function will usually be fully restored.
Clinically there will be complete loss of motor, sensory,
and sympathetic functions in the distribution of the
nerve. Axoplasmic regeneration will begin in approxi-
mately three weeks (6).
Reirrrrervatiorr would be expected to proceed in an or-
derly fashion, with proximal muscles being reinnervated
prior to distal, and proximal sensory returning prior to
distal. The standard estimates for regrowth once axo-
plasmic ﬂow has begun are approximately 1 inch/month
or 1 mm/day in an adult. One can calculate when return
of function can be expected by measuring from the site
of the lesion to the motor point of the first muscle or
sensory area supplied by the nerve.
In neurotmesis, or lesions in which the entire nerve
trunk is disrupted, no spontaneous return of function
would be anticipated. It is important to remember that
one cannot distinguish clinically between an axonotme-
sis and a neurotmesis on the basis of examination or
electrical studies. Both lesions show absence of function,
both clinically and electrically, and only direct explora-
tion of the nerve can differentiate them. How long to
wait before exploring a clinically complete lesion is a
question of surgical judgment.
DIAGNOSTIC TESTS
As in other medical fields, an accurate history and
careful examination are the most important elements of
diagnosis. A careful history will help differentiate trau-
matic neuropathies ﬁom those ofinfectious origin (diph-
theria, mumps, inﬂuenza, pneumonia, meningitis, ma-
laria, syphilis, typhoid, dysentery, tuberculosis, or
gonococcus) or metabolic causes (diabetes, rheumatoid
arthritis, gout, leukemia, vitamin deficiency, periarteritis
nodosa, sulfa, heavy metals, and carbon monoxide).

470 / CHAPTER 23
In the area of trauma, remote as well as recent injury
must be considered. Particular attention must be given
to the onset and course of the patient's symptoms. The
old neurologic adage holds that the history indicates the
pathology, and the examination gives the localization.
The examiner must also be aware of common anatomic
variations, such as overlap between the ulnar and me-
dian nerves in the hand, and must determine whether
the patient's course is progressive, static, or improving.
Electromyography and nerve conduction studies can
be helpful. Motor and sensory conduction studies are
done by using electric stimulation at one point on the
—nerve and recording at another. They reveal speed of
neural transmission, and an area of slowing may identify
the site of the lesion. Normal figures for conduction in
various nerve segments are available, and comparison
can also be made with the normal opposite side.
Nerye conduction varies with the size of the fiber and
the amount of myelin sheath: large, heavily myelinated
fibers are the most rapid conductors, and small, slightly
myelinated fibers are the slowest. Although a mixed
nerve consists of a combination of these two fibers as
well as their intermediate forms, the measured conduc-
tion velocity of a peripheral nerve will be that of the
fastest fiber.
Electromyography may reveal denervation potentials
in the affected muscles. The pattern of muscles involved
will help localize the lesion along the course of the nerve.
Subsequently, polyphasic potentials may indicate early
reinnervation prior to the presence of voluntary muscle
contractions. In addition, electrical studies may be help-
ful in differentiating organic pathology from a functional
state. If there is a question about the innervation of cer-
tain muscles or concern about aberrant innervation, lo-
cal anesthetic block of either the involved or the unin-
volved nerves will help delineate the situation.
With the history, clinical examination, and electrical
studies, one can make proper pathologic and anatomic
diagnosis in a high percentage of cases. Nevertheless, it is
not always possible to differentiate total physiologic loss
from anatomic disruption of the nerve. A signiﬁcant
diagnostic aid is repeated examinations to determine
whether the patient's status is improving or declining.
Valuable, but not infallible, is Tinel's sign: after a com-
plete nerye lesion axonal growth may be determined by
percussion over the nerye, with the paresthetic response
being evoked by tapping over the growth cone progres-
sively more distally over the nerve as regrowth occurs.
INDICATIONS FOR SURGERY
In lesions in continuity, such as contusions, compres-
sion, or injection palsy, when there is no reason to
suspect that the nerve has been divided, the pathologic
process is one of partial or complete physiologic in-
terruption, usually compounded by external and inter-
nal fibrosis. If such a lesion is progressive, with increas-
ing loss of motor and sensory function, surgical
exploration should be carried out as soon as the patient is
otherwise medically fit. If the lesion is profound at the
time of the first examination and no improvement is
evident within four to six weeks following onset, surgical
exploration is indicated (7). Surgery should be withheld
if improvement is apparent during the four to six weeks
of observation. Pain alone, without any sensory or mo-
tor symptomatology, is rarely an indication for periph-
eral nerve surgery.
Nerye lacerations may be treated by either primary or
secondary repair. Primary repair (8) should be reserved
for situations in which (1) the surgeon is experienced in
the repair of peripheral neryes; (2) the wound is a clean
laceration with no crushing of nerve or other tissues; (3)
the nerve ends are easily found without wound exten-
sion; (4) there is no wound contamination; and (5) sutur-
ing can be done without mobilization or tension. If these
conditions are not met, secondary repair is indicated.
The initial surgical treatment, pending secondary re-
pair, involves tagging the nerve ends with markers to try
to maintain axial orientation and suturing the ends in
approximation to prevent their retraction during wound
healing. Careful debridement of other tissues should be
carried out as indicated.
Definitive secondary repair (9, 10) should be done four
to six weeks later, when conditions should be optimum.
The initial wound should have healed without incident.
This delay will allow for resolution of the usual exuda-
tive phase of injury and for maturation of fibrous tissue.
This will make subsequent resection of proximal and
distal nerve ends more accurate. The epineurium will be
firmer and easier to suture. In addition, axoplasmic flow
will just be beginning in three weeks, and Wallerian de-
generation should be complete. Thus, anatomic and
physiological conditions are at the optimum.
With regard to nerve tumors, surgery should be under-
taken in the case of progressive loss of nerve function,
disabling symptoms, or suspicion of malignancy. Many
tumors will remain static for long periods of time, so
repeated observation is indicated to determine any need
for surgery.
PREOPERATIVE MANAGEMENT
Aside from careful neurologic evaluation, the patient's
general medical fitness should be established. Appro-
priate physiotherapy should be employed to maintain
range of motion and functional position, prevent edema,
and avoid pressure sores. Repeated examinations will
determine the patient's course. Any splints or casts that
might be needed in the immediate postoperative phase

can be prefabricated. It helps to try preoperatively plac-
ing the patient's limbs in the position in which the opera-
tion is planned, to make certain that there is no limita-
tion of the range of joint motion that would prevent
surgery in that position and that no compromise of neu-
rovascular structures would occur if the patient were
placed in that position for a long period of time. Careful
planning of the operative incision and review of anat-
omy and possible variations are advisable. Discussion
with the patient should include the patient's active role
in recovery and the risks and potential benefits of the
procedure.
OPERATIVE MANAGEMENT
Neurolysis
Lesions in continuity caused by extrinsic and intrinsic
scar tissue should be treated with external and internal
neurolysis. The former involves freeing the nerve from
its surrounding bed and from any extrinsic adhesions,
whereas the latter involves opening the nerve sheath and
dividing any scar constricting the fascicles (11,12). The
incision must be adequate to allow visualization of nor-
mal nerve on either side of the lesion. Pathology can be
localized by inspection and by palpation of the nerve and
surrounding structures. Thickening or abnormal firm-
ness is usually noted. The external findings are verified
when the nerve is opened and observed through the
operating microscope. Intraoperative electrical stimula-
tion above and below the level of the lesion both before
and after neurolysis may provide prognostic informa-
tion. The operating microscope and microinstruments
are employed, and the nerve sheath is opened with sharp
dissection. The fascicles are identified in the normal area
of nerve and then followed into and through the area of
PERIPHERAL NERVE INJURY / 471
scar, superficial to the fascicles. This will prevent injury
to any interfascicular plexuses. The nerve is rotated, and
multiple superficial incisions are used rather than nerve
penetration. Retraction is done only on the connective
tissue elements. Use of a number 12 blade will allow the
surgeon to be always cutting away from the nerve tissue
[Fig. 1(A)]. Meticulous hemostasis, effected with the mi-
crobipolar coagulator, and delicate tissue handling are
important. Following decompression, the epineurial
ﬂaps are generally resected [Fig. 1(B)]. Wound closure is
carried out with loose closure of deep fascia, subcutane-
ous sutures, and Steri—Tapes on the skin. No cast or im-
mobilization is required.
General anesthesia is usually used because the opera-
tion may last several hours and because any movement
of the patient could be disastrous. Surgery can usually be
done on an outpatient basis.
Nerve Suture
For similar reasons, general anesthesia is employed for
nerve suture, and a general preparation of the extremity
is done because extension ofthe incisions and mobiliza-
tion of the nerve may be required. After the nerve is
exposed, it must be mobilized sufficiently so that an ap-
proximation without tension can be accomplished (13).
Under the microscope, the end of the nerve must be
resected until relatively normal—appearing tissue is seen.
End—to—end anastomosis, utilizing an epineurial or fascic-
ular technique (14-16), is preferable (Figs. 2 and 3). This
may require extensive mobilization of the nerve to pro-
vide length, and it is accomplished primarily at the prox-
imal end because the acute angle of separation of distal
branches makes it more difficult to gain slack from the
distal segment.
FIG. 1. (A) The external nerve sheath is
opened with sharp dissection using the
operating microscope. The number 12
blade, with the blade directed away
from the fascicles, allows division ofthe
fibrous bands. (B) The completed dis-
section shows the various fascicles de-
compressed. The flaps of epineurium
can then be resected.

472 / CHAPTER 23
FIG. 2. End—to—end anastomosis. The suture is placed just
through the epineural tissue after axial orientation has been
established.
In addition, transposing a nerve, such as moving the
ulnar nerve anterior to the epicondyle at the elbow, may
help to add further length. Flexion of the limb is also
helpful, but it should not be employed beyond 90 de-
grees. A nerve reapproximated under such conditions
would probably be unable to withstand the tension on
the nerve when the limb is later extended. Use of the
microscope and rnicroinstrurnentation, delicate nerve
handling, careful hemostasis, accurate axial orientation
and coaptation of the nerve ends, lack of tension on the
suture line, and the use of a relatively inert suture mate-
rial (17) are the keys to success in nerve suture.
Should suturing prove impossible, autografting is the
best substitute currently available. A segment of the sural
or other sensory nerve may be employed with a fascicu—
lar suture technique, in which the ends of the injured
nerve are divided into groups of fascicles appropriate to
the number in the graft. End—to—end anastomosis of the
graft is carried out proximally and distally.
After nerve suturing, immobilization is indicated to
prevent disruption of the suture line, especially if ﬂexion
of the limb was required to perform the anastomosis.
Nerve tumors can often be resected using the neuroly—
sis technique. The fascicles can be separated longitudi-
nally, and the tumor can be shelled out of the nerve. lfa
malignant tumor is encountered, resection with gener-
ous margins is appropriate, with subsequent suturing or
grafting as the situation dictates.
FIG. 3. Fascicular anastomosis. The individual fascicles are
directly sutured after the adjacent epineurium has been re-
sected.
Outcome
No simple statement can be made about the results of
either neurolysis or nerve suture, but several factors can
be enumerated that are important in the quality of recov-
ery (18):
1. Type of nerve. A pure sensory or pure motor nerve
will do better than a mixed nerve in which motor and
sensory axons may enter opposite endoneurial tubes,
which will guide them to inappropriate targets.
2. Age of the patient. The younger the patient, the better
the prospects.
3. Level of injury. The more distal the lesion (i.e., the
closer the lesion is to the structures to be innervated
with respect to the total length of the nerve), the better
the prognosis.
4. Degree of deficit. In lesions in continuity, the more
profound the deﬁcit, the worse the prognosis.
5. Extent of the defect. Prospects are better with direct
nerve suture than with grafting.
6. Time from injury. The longer repair is delayed
beyond the ﬁrst few weeks or months, the poorer the
prognosis.
7. Surgical technique. The skill and experience of the
surgeon have a significant bearing on the outcome.
REFERENCES
1. Brown BA. Sciatic injection neuropathy: treatment by internal
neurolysis. CalifMed 1972;! 16:13-15.
2. Kopell HP, Thompson WAL. Peripheral entrapment neuropa-
thies. Baltimore: Williams and Wilkins, 1963.
3. Sunderland S. Nerves and nerve injuries. Edinburgh: ES Living-
stone, 1968.
4. Chusid I G, McDonald ll. Correlative anatomy and functional neu-
rology, 14th ed. Los Altos, CA: Lang Medical Publications, 1970.
5. Haymaker‘ W, Woodall B. Peripheral nerve injuries: principles of
diagnosis. Philadelphia: WB Saunders, 1956.
6. Ducker TB, Kempe LG, Hayes G]. The metabolic background for
peripheral nerve surgery. J Neurosurg 1969;30:270-280.
7. Brown HA. Contused injuries of peripheral nerves: the value of
early surgical treatment. Calif West Med 1934;41:116.
8. Sakellarides H. Follow—up study, 172 peripheral nerve injuries in
the upper extremities in children. J Bone Joint Surg [Am]
1962;44A:140.
9. Ducker TB, Kauffman FC. Metabolic factors in surgery of periph-
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