Acute hemichorea as an unusual presentation of internal carotid artery stenosis.

Involuntary movement associated with deep watershed ischemic lesions has been rarely reported. A 67-year-old woman presented with acute hemichorea on the left side. Magnetic resonance imaging showed acute infarcts in the anterior border zone. On perfusion studies, impaired cerebral blood flow was observed on the subcortical region sparing the basal ganglia. Cerebral angiogram confirmed severe stenosis in the right internal carotid artery. Her hemichorea gradually improved along with normalization of perfusion after carotid artery stenting with angioplasty. We suggest that impaired cerebral blood flow in critical watershed territories may be an important contributing factor in hemichorea associated with carotid occlusive disease.