A 68-year-old diabetic man develops sudden pure motor hemiplegia affecting the face, arm and leg on the left without any sensory loss, aphasia or visual field defect. CT shows a small lacunar infarct. Which arterial supply to the affected structure has been occluded?
- A Lenticulostriate branches of the middle cerebral artery supplying the posterior limb of the internal capsule ✓
- B Callosomarginal branch of the anterior cerebral artery
- C Anterior choroidal artery supplying the optic tract
- D Superior cerebellar artery supplying the midbrain tegmentum
Correct answer: A. Lenticulostriate branches of the middle cerebral artery supplying the posterior limb of the internal capsule
Explanation
Pure motor hemiplegia is the classic lacunar syndrome caused by infarction of the posterior limb of the internal capsule, where corticospinal and corticobulbar fibres are packed densely. The posterior limb is supplied by lenticulostriate branches of the middle cerebral artery, which are small penetrating end arteries prone to lipohyalinosis in hypertension and diabetes. Anterior choroidal infarcts usually add hemisensory loss and hemianopia, which this patient conspicuously lacks.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.