Do You Know About Small Vessel Stroke?

Small-Vessel Stroke The term lacunar infarction refers to infarction

following atherothrombotic or lipohyalinotic occlusion of a small artery(

30 to 300 _m) in the brain. The term small-vessel stroke denotes

occlusion of such a small penetrating arteryand is now the preferred

term. Small-vessel strokes account for _20% of all strokes.

PATHOPHYSIOLOGY The MCA stem, the arteries comprising the circle of

Willis (A1 segment, anterior and posterior communicating arteries,

and P1 segment), and the basilar and vertebral arteries all give rise to

30- to 300-_m branches that penetrate the deep grayand white matter

of the cerebrum or brainstem (Fig. 349-3). Each of these small

branches can occlude either byatherothrombotic disease at its origin

or bythe development of lipohyalinotic thickening. 

Thrombosis of

these vessels causes small infarcts that are referred to as lacunes (Latin

for “lake” of fluid noted at autopsy). They range in size from 3 mm

to 2 cm. Hypertension and age are the principal risk factors.

CLINICAL MANIFESTATIONS The most common lacunar syndromes are the

following: (1) Pure motor hemiparesis from an infarct in the posterior

limb of the internal capsule or basis pontis; the face, arm, and leg are

almost always involved; (2) pure sensory stroke from an infarct in the

ventrolateral thalamus; (3) ataxic hemiparesis from an infarct in the

base of the pons; (4) dysarthria and a clumsy hand or arm due to

infarction in the base of the pons or in the genu of the internal capsule;

and (5) pure motor hemiparesis with “motor (Broca’s) aphasia” due

to thrombotic occlusion of a lenticulostriate branch supplying the genu

and anterior limb of the internal capsule and adjacent white matter of

the corona radiata.

Transient symptoms (small vessel TIAs) may herald a small-vessel

infarct; theymay occur several times a day and last only a few minutes.

Recoveryfrom a small-vessel stroke often begins within hours or days,

and over weeks or months maybe nearly complete; in some cases,

however, there is severe permanent disability. Often, institution of

combined antithrombotic treatments does not prevent eventual stroke

in “stuttering lacunes.”

A large-vessel source (either thrombosis or embolism) maymanifest

initiallyas a lacunar syndrome with small-vessel infarction. Therefore,

the search for embolic sources (carotid and heart) should not be

completelyabandoned in the evaluation of these patients. Secondary

prevention of lacunar stroke involves risk factor modification, specificallyreduction

in blood pressure (see “Primary and Secondary Prevention,”

below).