Which small vessel is most commonly involved in lacunar infarcts causing a pure motor stroke?

• A. Anterior choroidal artery
• B. Lateral striate arteries
• C. Lenticulostriate arteries
• D. Posterior cerebral artery

Answer: (C)

Lacunar strokes that present with a pure motor deficit occur when a small penetrating artery supplying deep motor pathways is blocked. The most common vessel involved is the lenticulostriate arteries, tiny branches of the middle cerebral artery that feed the internal capsule and nearby basal ganglia. When these arteries develop a lacunar infarct, the corticospinal tract in the posterior limb of the internal capsule is affected, producing pure motor weakness without cortical signs like aphasia or neglect. Other vessels can cause overlapping deficits, but classic pure motor lacunes are most strongly linked to lenticulostriate arteries.