3325 Introduction to Cerebrovascular Diseases CHAPTER 426

or understand; or a sudden, severe headache. The acronym FAST

(facial weakness, arm weakness, speech abnormality, and time) is

simple and helpful to teach to the lay public about the common

physical symptoms of stroke and to underscore that treatments are

highly time sensitive.

Other causes of sudden-onset neurologic symptoms that may

mimic stroke include seizure, intracranial tumor, migraine, and

metabolic encephalopathy. An adequate history from an observer

that no convulsive activity occurred at the onset usually excludes

seizure (Chap. 425), although ongoing complex partial seizures

without tonic-clonic activity can on occasion mimic stroke.

Tumors (Chap. 90) may present with acute neurologic symptoms due to hemorrhage, seizure, or hydrocephalus. Surprisingly,

migraine (Chap. 430) can mimic stroke, even in patients without

a significant migraine history. When migraine develops without

head pain (acephalgic migraine), the diagnosis can be especially

difficult. Patients without any prior history of migraine may develop

acephalgic migraine even after age 65. A sensory disturbance is often

prominent, and the sensory deficit, as well as any motor deficits,

tends to migrate slowly across a limb, over minutes rather than seconds as with stroke. The diagnosis of migraine becomes more secure

as the cortical disturbance begins to cross vascular boundaries or if

classic visual symptoms are present such as scintillating scotomata.

At times, it may be impossible to make the diagnosis of migraine

until there have been multiple episodes with no residual symptoms or

signs and no changes on brain magnetic resonance imaging (MRI).

Metabolic encephalopathies typically produce fluctuating mental status changes without focal neurologic findings. However, in the setting

of prior stroke or brain injury, a patient with fever or sepsis may manifest a recurrent hemiparesis, which clears rapidly when the infection

is treated. The metabolic process serves to “unmask” a prior deficit.

Once the diagnosis of stroke is made, a brain imaging study is

necessary to determine if the cause of stroke is ischemia or hemorrhage (Fig. 426-1). Computed tomography (CT) imaging of the

brain is the standard imaging modality to detect the presence or

Stroke or TIA

ABCs, glucose

Hemorrhage

15%

Consider BP

lowering

Obtain brain

imaging

Ischemic stroke/

TIA, 85%

Consider thrombolysis/

thrombectomy

Establish cause Establish cause

Atrial

fibrillation,

17%

Carotid

disease,

4%

Aneurysmal

SAH, 4%

Hypertensive ICH, 7%

Other,

64%

Other,

4%

Consider

oral

anticoagulant

Consider

CEA or

stent

Consider

surgery

Treat

specific

cause

Treat

specific

cause

Deep venous thrombosis prophylaxis

Physical, occupational, speech therapy

Evaluate for rehab, discharge planning

Secondary prevention based on disease

Clip or coil

(Chap. 429)

FIGURE 426-1 Medical management of stroke and TIA. Rounded boxes are

diagnoses; rectangles are interventions. Numbers are percentages of stroke

overall. ABCs, airway, breathing, circulation; BP, blood pressure; CEA, carotid

endarterectomy; ICH, intracerebral hemorrhage; SAH, subarachnoid hemorrhage;

TIA, transient ischemic attack.

absence of intracranial hemorrhage (see “Imaging Studies,” below).

If the stroke is ischemic, administration of recombinant tissue plasminogen activator (rtPA) or endovascular mechanical thrombectomy may be beneficial in restoring cerebral perfusion (Chap. 427).

Medical management to reduce the risk of complications becomes

the next priority, followed by plans for secondary prevention. For

ischemic stroke, several strategies can reduce the risk of subsequent

stroke in all patients, while other strategies are effective for patients

with specific causes of stroke such as cardiac embolus and carotid

atherosclerosis. For hemorrhagic stroke, aneurysmal subarachnoid

hemorrhage (SAH) and hypertensive intracerebral hemorrhage are

two important causes. The treatment and prevention of hypertensive intracerebral hemorrhage are discussed in Chap. 428. SAH

is discussed in Chap. 429.

■ STROKE SYNDROMES

A careful history and neurologic examination can often localize the

region of brain dysfunction; if this region corresponds to an arterial

distribution, the possible causes responsible for the syndrome can be

narrowed. This is of particular importance when the patient presents

with a TIA and a normal examination. For example, if a patient develops language loss and a right homonymous hemianopia, a search for

causes of left middle cerebral emboli should be performed. A finding

of an isolated stenosis of the right internal carotid artery in that patient,

for example, suggests an asymptomatic carotid stenosis, and the search

for other causes of stroke should continue. The following sections

describe the clinical findings of cerebral ischemia associated with cerebral vascular territories depicted in Figs. 426-2 through 426-11. Stroke

syndromes are divided into (1) large-vessel stroke within the anterior

circulation, (2) large-vessel stroke within the posterior circulation, and

(3) small-vessel disease of either vascular bed.

Stroke within the Anterior Circulation The internal carotid

artery and its branches compose the anterior circulation of the brain.

These vessels can be occluded by intrinsic disease of the vessel (e.g.,

atherosclerosis or dissection) or by embolic occlusion from a proximal

source as discussed above. Occlusion of each major intracranial vessel

has distinct clinical manifestations.

MIDDLE CEREBRAL ARTERY Occlusion of the proximal middle cerebral artery (MCA) or one of its major branches is most often due to

an embolus (artery-to-artery, cardiac, or of unknown source) rather

than intracranial atherothrombosis. Atherosclerosis of the proximal

MCA may cause distal emboli to the middle cerebral territory or,

less commonly, may produce low-flow TIAs. Collateral formation via

leptomeningeal vessels often prevents MCA stenosis from becoming

symptomatic.

The cortical branches of the MCA supply the lateral surface of

the hemisphere except for (1) the frontal pole and a strip along the

superomedial border of the frontal and parietal lobes supplied by the

anterior cerebral artery (ACA) and (2) the lower temporal and occipital

pole convolutions supplied by the posterior cerebral artery (PCA)

(Figs. 426-2–426-5).

The proximal MCA (M1 segment) gives rise to penetrating branches

(termed lenticulostriate arteries) that supply the putamen, outer globus

pallidus, posterior limb of the internal capsule, adjacent corona radiata,

and most of the caudate nucleus (Fig. 426-2). In the sylvian fissure, the

MCA in most patients divides into superior and inferior divisions (M2

branches). Branches of the inferior division supply the inferior parietal

and temporal cortex, and those from the superior division supply the

frontal and superior parietal cortex (Fig. 426-3).

If the entire MCA is occluded at its origin (blocking both its penetrating and cortical branches) and the distal collaterals are limited,

the clinical findings are contralateral hemiplegia, hemianesthesia,

homonymous hemianopia, and a day or two of gaze preference to

the ipsilateral side. Dysarthria is common because of facial weakness.

When the dominant hemisphere is involved, global aphasia is present

also, and when the nondominant hemisphere is affected, anosognosia,

constructional apraxia, and neglect are found (Chap. 30).

3326 PART 13 Neurologic Disorders

Putamen

Internal

capsule

Uncus

Claustrum

Caudate

Middle cerebral

a. (M2)

Lenticulostriate as.

Post cerebral a.

Deep branches of ant. cerebral a.

Deep branches of middle cerebral a.

Middle cerebral a.

Ant. cerebral a.

KEY

Anterior

cerebral a. (A2)

Anterior

cerebral a. (A1)

Internal carotid a. Middle cerebral a. (M1)

FIGURE 426-2 Diagram of a cerebral hemisphere in coronal section showing the

territories of the major cerebral vessels that branch from the internal carotid arteries.

Complete MCA syndromes occur most often when an embolus

occludes the stem of the artery. Cortical collateral blood flow and

differing arterial configurations are probably responsible for the

development of many partial syndromes. Partial syndromes may

also be due to emboli that enter the proximal MCA without complete occlusion, occlude distal MCA branches, or fragment and

move distally.

Partial syndromes due to embolic occlusion of a single branch

include hand, or arm and hand, weakness alone (brachial syndrome) or facial weakness with nonfluent (Broca) aphasia (Chap.

30), with or without arm weakness (frontal opercular syndrome).

A combination of sensory disturbance, motor weakness, and nonfluent aphasia suggests that an embolus has occluded the proximal superior division and infarcted large portions of the frontal

and parietal cortices (Fig. 426-3). If a fluent (Wernicke’s) aphasia

occurs without weakness, the inferior division of the MCA

supplying the posterior part (temporal cortex) of the dominant

hemisphere is probably involved. Jargon speech and an inability to comprehend written and spoken language are prominent

features, often accompanied by a contralateral, homonymous

superior quadrantanopia. Hemineglect or spatial agnosia without

weakness indicates that the inferior division of the MCA in the

nondominant hemisphere is involved.

Occlusion of a lenticulostriate vessel produces small-vessel

(lacunar) stroke within the internal capsule (Fig. 426-2). This

produces pure motor stroke or sensory-motor stroke contralateral to the lesion. Ischemia within the genu of the internal capsule

causes primarily facial weakness followed by arm and then leg

KEY

Rolandic a.

Prerolandic a.

Sup. division

middle cerebral a.

Lateral

orbitofrontal a.

Temporopolar a.

Inf. division

middle cerebral a.

Ant. temporal a.

Post. temporal a.

Angular a.

Post. parietal a.

Ant. parietal a.

Visual radiation

Broca's area Sensory cortex Auditory area

Contraversive

eye center

Wernicke's

aphasia area

Visual cortex

Motor cortex

FIGURE 426-3 Diagram of a cerebral hemisphere, lateral aspect, showing the branches and distribution of the middle cerebral artery (MCA) and the principal regions of

cerebral localization. Note the bifurcation of the MCA into a superior and inferior division.

Signs and symptoms: Structures involved

Paralysis of the contralateral face, arm, and leg; sensory impairment over the same area (pinprick, cotton touch, vibration, position, two-point discrimination, stereognosis, tactile localization, barognosis, cutaneographia): Somatic motor area for face and arm and the fibers descending from the leg area to enter the corona radiata and

corresponding somatic sensory system

Motor aphasia: Motor speech area of the dominant hemisphere

Central aphasia, word deafness, anomia, jargon speech, sensory agraphia, acalculia, alexia, finger agnosia, right-left confusion (the last four comprise the Gerstmann

syndrome): Central, suprasylvian speech area and parietooccipital cortex of the dominant hemisphere

Conduction aphasia: Central speech area (parietal operculum)

Apractagnosia of the nondominant hemisphere, anosognosia, hemiasomatognosia, unilateral neglect, agnosia for the left half of external space, dressing “apraxia,”

constructional “apraxia,” distortion of visual coordinates, inaccurate localization in the half field, impaired ability to judge distance, upside-down reading, visual illusions

(e.g., it may appear that another person walks through a table): Nondominant parietal lobe (area corresponding to speech area in dominant hemisphere); loss of topographic memory is usually due to a nondominant lesion, occasionally to a dominant one

Homonymous hemianopia (often homonymous inferior quadrantanopia): Optic radiation deep to second temporal convolution

Paralysis of conjugate gaze to the opposite side: Frontal contraversive eye field or projecting fibers

3327 Introduction to Cerebrovascular Diseases CHAPTER 426

Secondary

motor area

Medial

prerolandic a.

Callosomarginal a.

Frontopolar a.

Medial orbitofrontal a.

Ant. cerebral a.

Post. communicating a.

Penetrating

thalamosubthalamic

paramedian As.

Calcarine a.

Parietooccipital a.

Medial posterior choroidal a.

Pericallosal a. Post.

parietal a.

Splenial a.

Post. thalamic a.

Lateral posterior

choroidal a.

Post. temporal a.

Ant.

temporal a.

Post.

cerebral

stem

Visual

cortex

Sensory

cortex

Motor

cortex

Hippocampal As.

Medial

rolandic a.

Striate area

along calcarine

sulcus

FIGURE 426-4 Diagram of a cerebral hemisphere, medial aspect, showing the branches and distribution of the anterior cerebral artery and the principal regions of cerebral

localization.

Signs and symptoms: Structures involved

Paralysis of opposite foot and leg: Motor leg area

A lesser degree of paresis of opposite arm: Arm area of cortex or fibers descending to corona radiata

Cortical sensory loss over toes, foot, and leg: Sensory area for foot and leg

Urinary incontinence: Sensorimotor area in paracentral lobule

Contralateral grasp reflex, sucking reflex, gegenhalten (paratonic rigidity): Medial surface of the posterior frontal lobe; likely supplemental motor area

 Abulia (akinetic mutism), slowness, delay, intermittent interruption, lack of spontaneity, whispering, reflex distraction to sights and sounds: Uncertain localization—

probably cingulate gyrus and medial inferior portion of frontal, parietal, and temporal lobes

Impairment of gait and stance (gait apraxia): Frontal cortex near leg motor area

Dyspraxia of left limbs, tactile aphasia in left limbs: Corpus callosum

weakness as the ischemia moves posterior within the capsule. Alternatively, the contralateral hand may become ataxic, and dysarthria will

be prominent (clumsy hand, dysarthria lacunar syndrome). Lacunar

infarction affecting the globus pallidus and putamen often has few clinical signs, but parkinsonism and hemiballismus have been reported.

ANTERIOR CEREBRAL ARTERY The ACA is divided into two segments: the precommunal (A1) circle of Willis, or stem, which connects

the internal carotid artery to the anterior communicating artery, and

the postcommunal (A2) segment distal to the anterior communicating

artery (Figs. 426-2 and 426-4). The A1 segment gives rise to several

deep penetrating branches that supply the anterior limb of the internal

capsule, the anterior perforate substance, amygdala, anterior hypothalamus, and the inferior part of the head of the caudate nucleus.

Occlusion of the proximal ACA is usually well tolerated because of

collateral flow through the anterior communicating artery and collaterals through the MCA and PCA. Occlusion of a single A2 segment

results in the contralateral symptoms noted in Fig. 426-4. If both A2

segments arise from a single anterior cerebral stem (contralateral A1

segment atresia), the occlusion may affect both hemispheres. Profound

abulia (a delay in verbal and motor response) and bilateral pyramidal

signs with paraparesis or quadriparesis and urinary incontinence

result.

ANTERIOR CHOROIDAL ARTERY This artery arises from the internal

carotid artery and supplies the posterior limb of the internal capsule

and the white matter posterolateral to it, through which pass some

of the geniculocalcarine fibers (Fig. 426-5). The complete syndrome

of anterior choroidal artery occlusion consists of contralateral hemiplegia, hemianesthesia (hypesthesia), and homonymous hemianopia.

However, because this territory is also supplied by penetrating vessels

of the proximal MCA and the posterior communicating and posterior

choroidal arteries, minimal deficits may occur, and patients frequently

recover substantially. Anterior choroidal strokes are usually the result

of in situ thrombosis of the vessel, and the vessel is particularly vulnerable to iatrogenic occlusion during surgical clipping of aneurysms

arising from the internal carotid artery.

INTERNAL CAROTID ARTERY The clinical picture of internal carotid

occlusion varies depending on whether the cause of ischemia is

propagated thrombus, embolism, or low flow. The cortex supplied by

the MCA territory is affected most often. With a competent circle of

Willis, occlusion may go unnoticed. If the thrombus propagates up the

internal carotid artery into the MCA or embolizes it, symptoms are

identical to proximal MCA occlusion (see above). Sometimes there is

massive infarction of the entire deep white matter and cortical surface.

When the origins of both the ACA and MCA are occluded at the top

of the carotid artery, abulia or stupor occurs with hemiplegia, hemianesthesia, and aphasia or anosognosia. When the PCA arises from the

internal carotid artery (a configuration called a fetal PCA), it may also

become occluded and give rise to symptoms referable to its peripheral

territory (Figs. 426-4 and 426-5).

In addition to supplying the ipsilateral brain, the internal carotid

artery perfuses the optic nerve and retina via the ophthalmic artery.

In ~25% of symptomatic internal carotid disease, recurrent transient

monocular blindness (amaurosis fugax) warns of the lesion. Patients

typically describe a horizontal shade that sweeps down or up across the

field of vision. They may also complain that their vision was blurred in

that eye or that the upper or lower half of vision disappeared. In most

cases, these symptoms last only a few minutes. Rarely, ischemia or

infarction of the ophthalmic artery or central retinal arteries occurs at

the time of cerebral TIA or infarction.