Localization in Clinical Neurology

663 Pages·2011·14.44 MB·English

by  Paul W. Brazis

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Paul W.Brazis,MD
Professor of Neurology
Consultant in Neurology and Neuroophthalmology
Mayo Clinic—Jacksonville
Jacksonville,Florida
Joseph C.Masdeu,MD,PhD
Senior Staff Physician and Scientist
Section on Integrative Neuroimaging
National Institutes of Health
Bethesda,Maryland
Adjunct Professor of Neurology
New York Medical College
Valhalla,New York
José Biller,MD,FACP,FAAN,FAHA
Professor and Chairman
Department of Neurology
Loyola University Chicago
Stritch School of Medicine
Maywood,Illinois
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Sixth Edition
Printed in China
Library of Congress Cataloging-in-Publication Data
Brazis, Paul W.
Localization in clinical neurology / Paul W. Brazis, Joseph C. Masdeu, José Biller. – 6th ed.
p. ; cm.
Includes bibliographical references and index.
ISBN-13: 978-1-60913-281-1 (alk. paper)
ISBN-10: 1-60913-281-5 (alk. paper)
1. Nervous system--Diseases--Diagnosis. 2. Brain–Localization of functions. I. Masdeu, Joseph C. II. Biller,
José. III. Title.
[DNLM: 1. Nervous System Diseases--diagnosis. 2. Diagnostic Techniques, Neurological. WL 141]
RC348.B73 2011
616.8(cid:2)0475–dc22
2010050172
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This volume is dedicated to Drs. Frank Rubino and Sudhansu Chokroverty,
who first taught us the skills and value of localization in clinical neurology.
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Preface
This new edition of Localization in Clinical Neurology G. Lee, Frank A. Rubino, Jonathan D. Trobe, James
is again written for “frontline” clinicians who care J. Corbett, James Bolling, and Michael Stewart.
for patients with neurologic disease processes and Dr. Masdeu acknowledges the help of many
who are confronted with the “Where is it?” of neuro- colleagues and friends, too many to be mentioned by
logic disorders. This edition contains much updated name, particularly at the New York Medical College,
information, some new charts on the differential the Medical School of the University of Navarra, and
diagnosis of clinical entities, and upgraded images to the Section on Integrative Neuroimaging at the
aid in neurologic localization, in addition to a new National Institutes of Health.
chapter on the localization of lesions of the auto- Dr. Biller is indebted to his colleagues at Loyola
nomic nervous system. We hope that this volume University Chicago, and foremost to his wife,
may help in the clinician’s quest to diagnose patients Rhonda, his children, stepchildren, and his grand-
with neurologic problems with greater accuracy and son, Selim, for their constant encouragement and
the least cost. unfailing patience.
Dr. Brazis especially expresses his appreciation
to his colleagues at the Mayo Clinics in Jacksonville, Paul W. Brazis
Scottsdale, and Rochester and expresses his gratitude Joseph C. Masdeu
to his teachers and friends: Drs. Neil Miller, Andrew José Biller
iv
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Contents
Preface iv
1
General Principles of Neurologic Localization 1
2
Peripheral Nerves 25
3
Cervical, Brachial, and Lumbosacral Plexi 73
4
Spinal Nerve and Root 89
5
Spinal Cord 99
6
Cranial Nerve I (The Olfactory Nerve) 127
7
Visual Pathways 133
8
The Localization of Lesions Affecting the
Ocular Motor System 173
9
Cranial Nerve V (The Trigeminal Nerve) 305
10
Cranial Nerve VII (The Facial Nerve) 321
11
Cranial Nerve VIII (The Vestibulocochlear Nerve) 341
12
Cranial Nerves IX and X (The Glossopharyngeal
and Vagus Nerves) 361
13
Cranial Nerve XI (The Spinal Accessory Nerve) 369
14
Cranial Nerve XII (The Hypoglossal Nerve) 377
15
Brainstem 385
16
The Cerebellum 403
17
The Localization of Lesions Affecting the
Hypothalamus and Pituitary Gland 419
18
The Anatomic Localization of Lesions
in the Thalamus 435
19
Basal Ganglia 455
v
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vi Contents
20
The Localization of Lesions Affecting the
Cerebral Hemispheres 493
21
Localization of Lesions in the Autonomic
Nervous System 557
22
Vascular Syndromes of the Forebrain, Brainstem,
and Cerebellum 567
23
The Localization of Lesions Causing Coma 603
Index 631
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General Principles of
1
Neurologic Localization
Introduction If thou examinest a man having a wound in his temple,
penetrating to the bone, (and) perforating his temporal
bone; . . . if thou ask of him concerning his malady and
Fittingly, a book on localization in clinical neurology
he speak not to thee; while copious tears fall from both
should begin with a chapter explaining what the
his eyes, so that he thrusts his hand often to his face so
term localization means. Localization derives from
that he may wipe both his eyes with the back of his
the Latin term locusor site. Localization is the diag- hand . . . Edwin Smith surgical papyrus, Case 20, 2800
nostic exercise of determining from the signs (most BC[12].
often) or symptoms of the patient what site of the ner-
From the time of Hippocrates, in ancient
vous system has been affected by a disease process.
Greece, it was documented that injury to the left part
Important injury to the nervous system results in
of the brain resulted in weakness of the right side of
abnormal function, be it behavioral, motor, or sen-
the body. However, paired organs in the body were
sory. Characteristics of the dysfunction often pave
thought to have identical functions. In the mid-19th
the way for a topographic (from the Greek term topos
century, Paul Broca (1824–1880) revolutionized the
or place) diagnosis. Localization and topographic
then current understanding of the functional organi-
diagnosis refer to the same thing: the determination
zation of paired organs by describing lateralization of
of where in the nervous system the damage has
language to the left hemisphere [5,13]. He called
occurred.
aphemiathe disorder that we now call Broca’s aphasia.
Even in the age of sophisticated neurophysiology,
In his 1865 paper, he wrote:
neuroimaging, and molecular biology, the clinical
diagnosis should precede the use of these other tech- Now, this function of the intellectual order, which
niques if their full diagnostic potential is to be realized. controls the dynamic element as well as the mechani-
Clinical localization has particular relevance to the cal element of articulation, seems to be the nearly
adequate use of ancillary procedures. For instance, constant privilege of the left hemisphere convolu-
tions, since lesions that result in aphemia are almost
false-positive findings from “gunshot approach” neu-
always localized in that hemisphere . . . That is tanta-
roimaging can only be avoided by careful localization.
mount to saying that we are left-brained with regard to
As an example, congenital brain cysts, strikingly visible
language. Just as we control movements in writing,
on imaging procedures, are often wrongly blamed for
drawing, embroidering, etc, with the left hemisphere,
a variety of neurologic disorders, while the actual dis- so we speak with the left hemisphere.
ease remains overlooked and untreated. The thought-
Broca defined the inferior frontal gyrus as the
ful use of ancillary procedures in neurology, guided by
area that, when injured, would lead to aphemia
clinical localization, minimizes discomfort for patients
[13]. He also noted the variation in the expression
and the waste of resources.
of diverse lesions in the inferior frontal gyrus,
characteristic of the plasticity found in cortical orga-
A Brief History of Localization:
nization:
Aphasia as an Example
During the course of our study of brains of patients
The history of localization is the history of early neurol- with aphemia, many times before, we had determined
ogy, concerned with topographic diagnosis that would that the lesion of the third left frontal convolution was
eventually lead to therapy. In few areas of neurology not always in direct relation to the intensity and
was the development of localization as interesting and the impairment of language. For example, we had
so much at the center of famous controversies as it observed that speech was completely wiped out as a
was in the case of aphasia. In fact, the oldest known result of a lesion with the size of 8 to 10 mm, whereas,
in other cases, lesions that were tenfold more extensive
document on neurologic localization concerns apha-
had only partly impaired the capacity for articulate
sia. It was recorded in an Egyptian papyrus from the
speech.
Age of the Pyramids (about 3000–2500 BC), where an
Egyptian surgeon described the behavior of an aphasic In the few years after Broca’s remarkable state-
individual: ments, knowledge about the localization of the
1
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2 Localization in Clinical Neurology
language centers in the brain grew rapidly. Already Current techniques, such as functional brain
in 1874, Carl Wernicke (1848–1905) wrote: mapping, promise to clarify further the localization
of mechanisms underlying neurologic dysfunction.
The whole area of convolution encircling the Sylvian
For instance, conduction aphasia, initially described
fissure, in association with the cortex of the insula,
by Wernicke in 1874, has traditionally been associ-
serves as a speech center. The first frontal gyrus, being
motor, is the center for representation of movement, ated with damage of the arcuate fasciculus, purport-
and the first temporal gyrus, being sensory, is the center edly connecting Wernicke’s with Broca’s area. Recent
for word images . . . The first temporal gyrus should be neurophysiological and neuroimaging findings, obta-
considered as the central end of the auditory nerve, and ined with the use of diffusion tensor imaging and
the first frontal gyrus (including Broca’s area) as the other functional magnetic resonance imaging (MRI)
central end of the nerves to the speech muscles . . . techniques, are challenging this notion [6].
Aphasia can result from any interruption of this path . . .
Knowledge of the cortical organization for lan-
guage had been derived from careful clinicopatho-
Clinical Diagnosis and
logic correlation [67]. After describing a 73-year-old
Lesion Localization
woman with the sudden onset of confused speech,
Wernicke goes on to describe the pathologic findings:
Clinical diagnosis in neurology requires several steps:
The branch of the artery of the left Sylvian fissure,
running down into the inferior sulcus of Burdach, was 1. Recognition of impaired function
occluded by a thrombus tightly adherent to the wall. 2. Identification of what site of the nervous system
The entire first temporal gyrus, including its junction has been affected, that is, localization
with the second temporal gyrus and the origin of the
3. Definition of the most likely etiology, often result-
latter from Bischof’s inferior parietal lobule were con-
ing in a differential diagnostic list
verted into a yellowish-white brei [67,68].
4. Use of ancillary procedures to determine which of
Wernicke’s diagram of the language areas is the different possible etiologies is present in the
illustrated in Figure 1.1. given patient
FIG. 1.1. Wernicke’s diagram of the language areas. In the original, the label on the superior temporal gyrus
was simply a, but from the context, it should have been a. Wernicke’s explanation of this figure is as follows:
1
Let Fbe the frontal, Othe occipital, and Tthe temporal end of a schematically drawn brain. Cis the central fissure;
around the Sylvian fissure (S) extends the first primitive convolution. Within this convolution, aiis the central end of
the acoustic nerve, aits site of entry into the medulla oblongata; bdesignates the representation of movements govern-
ing sound production, and is connected with the preceding through the association fibers aibrunning in the cortex of
the insula. From bthe efferent pathways of the sound-producing motor nerves run to the oblongata and exit there . . .
(From:Wernicke C, Der aphasische symptomencomplex; eine psychologische studie auf anatomischer basis, Bres-
lau: Max Cohn & Weigert, 1874 [67].)
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General Principles of Neurologic Localization 3
Each of these steps is important. The first one, istic radicular nature and distribution. In other
recognition of impaired function, depends on a good cases, the neurologic examination may reveal
history and neurologic examination. Only by storing other manifestations of unquestionable neurologic
the range of normal neurologic functions in their mind dysfunction. A patient with pain in the hand may
can physicians recognize an abnormal neurologic also have atrophy of the muscles in the thenar emi-
function. Inexperience or carelessness in examining a nence and a Tinel’s sign—pain on percussion of
patient often results in overlooking a neurologic deficit the median nerve at the wrist. Knowledge of local-
and therefore missing a diagnosis. For instance, mild ization tells us that the pain derives from injury of
chorea may appear to the inexperienced as normal fid- the median nerve at the point where the pain
getiness. The slow eye movements of a pontocerebellar increases on percussion. What is needed to local-
disorder may pass completely unrecognized by some- ize the lesion, in this case as in any other, is a good
one who looks only for a full excursion of the eyes. working knowledge of neuroanatomy.
Abnormal neurologic findings come in the
Neuroanatomy is a key to localization. In this
form of abnormal behavior, impaired posture or gait,
book, a synopsis of the anatomy of each structure of
difficulty with movements of the face or extremities,
the nervous system precedes the discussion on local-
and, finally, sensory disturbances, including pain.
ization of lesions of that structure. Neuroanatomy
Pain exemplifies well several of the difficulties physi-
has two broad aspects: the morphology of the struc-
cians face when confronting possible neurologic
ture and its “functional representation.” Functional
dysfunction.
representation refers to the function mediated by a
1. First, is the dysfunction real? Is the pain really given structure of the nervous system. Damage to the
there or is the patient trying to deceive? We have structure alters the function mediated by this struc-
witnessed the plight of a paraplegic patient who ture. For example, an injury to the oculomotor nerve
had been repeatedly asked by health care person- results in mydriasis in the eye supplied by this nerve.
nel to stop pretending not to be able to move his Neuroanatomy provides the road map for local-
legs. They had misinterpreted the triple flexion ization. Localizing is identifying the site of injury on
response witnessed when they pulled the sheets the neuroanatomic map. As with any other map, we
off the patient’s legs as evidence of volitional need either an address, with street name and num-
movement. Movement disorders, such as the dys- ber, or the intersection between two well-defined
tonias, were frequently considered psychogenic in streets or roads. Injury expresses itself through neuro-
the past and have gradually emerged from this logic dysfunction, be it behavioral, motor, or sensory.
realm into a phase of general recognition of their If we know what kind of dysfunction can result from
“organicity.” Unless accompanied by clear psychi- injury of the different parts of the nervous system, we
atric manifestations, neurologic symptoms or will be able to identify the source of the injury. Some
signs should be taken at face value. types of dysfunction directly give us the address we
2. Second, to what extent is the dysfunction patho- are looking for. A combination of resting tremor,
logic, that is, indicative of injury serious enough to bradykinesia, and rigidity tells us that the substantia
warrant a formal diagnostic workup? Many aches nigra of the patient has been injured. At other times,
and pains do not reflect serious disease. Sending we use the approach of looking for the intersection
everyone with a “little pain” to a physician would between two streets. From some signs we deduce that
hopelessly clog up the health care system. Interest- a particular pathway must be affected. From others,
ingly, the child learns from falls and other minor we infer that a second pathway is affected as well.
injuries what to expect as “normal pain,” and when a The injury must be in the place where these path-
person seeks medical attention for any symptom, the ways meet. For instance, by the presence of left-sided
likelihood is that the problem is serious enough to hemiparesis we infer that the corticospinal tract has
warrant at least a thoughtful physical examination. been affected. But the corticospinal tract can be
3. Third, is the dysfunction neurologic in origin? Is affected at the level of the spinal cord, brainstem, or
the pain due to injury of the affected body part or cerebral hemispheres. To precisely identify the loca-
neurologic dysfunction? Is the dysfunction a man- tion of damage we need to use other clues. If, in
ifestation of a disease of the nervous system rather addition to the left-sided hemiparesis, we find a
than of the organ mediating the function? Is the right third nerve palsy, we are well on our way to
patient unable to walk because of arthritis or localizing the lesion. This well-known syndrome,
because the motor system is affected? All these named after Weber, typifies a general principle of
questions find an answer when the physician localization: the lesion is where the two affected
recognizes patterns that belie neurologic impair- pathways cross. If the patient only had a third nerve
ment, for instance, in the case of pain, a character- palsy, the lesion could be anywhere between the
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4 Localization in Clinical Neurology
fascicle of the nerve (in the brainstem) and the supe- normal way. Any difficulty repeating a sentence on
rior orbital foramen (in the orbit). The addition of a the part of a native speaker of a language should be
contralateral hemiparesis precisely defines that the considered as abnormal. Higher neurologic function
lesion affects the crus cerebri on the same side of the should be sampled enough to avoid missing a deficit
third nerve palsy. This is where the corticospinal tract that the more complex neural networks of higher lev-
and the fibers of the third nerve meet. Neuroanatomy els can easily mask.
provides the roadmap for a correct assessment. For the anatomic localization of lesions, the
Localization tends to be more precise when the neurologic examination is much more important
lesion affects the lower levels of the nervous system. than the history. It must be noted that when we speak
When we localize lesions of the nervous system, it is here about “examination,” we include the sensory
helpful to think about the major syndromes that findings reported by the patient during the examina-
result from lesions at different functional and tion. A complaint of pain or of numbness is usually as
anatomic levels, from the muscle to the cortex. At the “objective” as a wrist drop. By tracking back the path-
simplest level, injury to a muscle impairs the move- ways that mediate the functions that we find are
ment mediated by that muscle. One level higher, we impaired in the neurologic examination, we can gen-
find that injury to a peripheral nerve causes weakness erally localize the site of the lesion, even without a
of the muscles innervated by that nerve and sensory history. The history, that is, the temporal evolution of
loss in its cutaneous distribution. Lesions in the the deficits witnessed in the neurologic examination,
spinal cord below the low cervical level cause weak- is important in defining the precise etiology. For
ness of one or both legs and sensory loss that often instance, a left-sided hemiparesis is detected in the
has a horizontal level in the trunk. Lesions in the neurologic examination. If it occurred in a matter of
cervical cord or brainstem typically cause weakness minutes, cerebrovascular disease or epilepsy is most
or sensory loss on one or both sides of the body, often likely. If it evolved over a few days, we should think
more severe on one side, and findings characteristic about an infection or demyelinating disease. If it
of the level affected. For instance, lesions of the cer- developed insidiously, in a matter of months, a tumor
vical cord may cause radicular pain or weakness or a degenerative process is more likely. In all of
affecting the arms or hands. Lesions of the lower these cases, the localization is derived from the find-
pons give rise to gaze palsies or peripheral facial ings of the examination: we detect a left-sided hemi-
weakness. The localization of lesions in the cranial paresis. If we also find a right third nerve palsy and
nerves (CNs) is fairly straightforward because they determine that it has appeared at the same time as
may affect a peripheral nerve or a neuroanatomic the hemiparesis, we will emphasize the need for a
structure that is relatively simple, such as the visual careful look at the midbrain when we obtain an
pathways. As we ascend the neuraxis, the localization MRI. In this sense, the history is also important for
of lesions becomes less precise. Lesions in the cere- localization: we may witness in the examination the
bellum may cause ataxia. Lesions in the thalamus end result of multiple lesions that affected the ner-
often, but not always, cause sensory loss and postural vous system over time. In the previous example, if
disorders, or memory loss. Lesions in the hemi- the third nerve palsy occurred when the patient was
spheric white matter may give rise to weakness or 10 years old and the hemiparesis appeared when he
visual field defects. Finally, lesions in the cortex was in his sixties, the lesion responsible for the hemi-
manifest themselves by an array of motor, sensory, or paresis would probably not be in the midbrain.
behavioral findings that vary according to the area Finally, there is the issue of discrete lesions ver-
that has been injured. sus system lesions. Much of the work on localization
Similarly, lesions of the lower levels tend to has been done on the basis of discrete lesions, such as
cause findings that change little over time, whereas an infarct affecting all the structures in the right side
lesions of the higher levels may be very “inconsis- of the pons. Some types of pathologies tend to cause
tent” in the course of an examination. An ulnar nerve this type of lesion. Cerebrovascular disease is the
lesion may be responsible for atrophy of the first dor- most common, but demyelinating lesions, infec-
sal interosseous muscle. The atrophy diagnosed by tions, trauma, and tumors also often behave like dis-
the examiner will be consistent. By contrast, a patient crete, single, or multiple lesions. Other neurologic
with a Broca’s aphasia may have a great deal of disorders affect arrays of neurons, often responsible
difficulty repeating some words, but not others of for a functional system. Parkinson’s disease is an
apparently similar difficulty. The examiner may be example. Here, the localization to the substantia
puzzled and not know what to document: can the nigra is simple. The localization of other degenera-
patient repeat or can she not? In this case, what tive disorders, such as the spinocerebellar degenera-
should be noted is not whether the patient can do tion of abetalipoproteinemia or vitamin E deficiency,
something, but whether she does it consistently in a is more complicated [56]. Here, the clinical syndrome