Alternating paroxysmal hemiballism-hemichorea in bilateral internal carotid artery stenosis.

A 72-year-old man presented with paroxysmal and transient involuntary movements, or "limb shaking". The attacks occurred alternately from one side of the body to the other and ceased spontaneously. Surface EMG study showed synchronous grouping discharges in multiple limb muscles, being compatible with hemiballism-hemichorea. Cerebral angiography demonstrated marked stenosis of the bilateral internal carotid arteries. Bilateral carotid endarterectomy led to complete disappearance of the involuntary movements. Alternating paroxysmal hemiballismhemichorea might be a transient ischemic attack, and alternating striatal dysfunction induced by cerebral hemodynamic or microembolic ischemia probably plays a central role in the occurrence of such involuntary movements.