Electrophysiological analysis of motor control in patients with vascular hemichorea.

An EMG analysis of motor control was performed in 4 patients with unilateral choreic movements of sudden onset, 3 of whom presented CT scan evidence of lacunar infarcts involving the contralateral striatum. The choreic dyskinesias were correlated with EMG bursts of variable duration occurring with a random order of activation. Ballistic elbow flexion movements were performed with a normal triphasic EMG pattern, but both size and duration of the first agonist burst were increased on the affected side. Abnormalities of cerebral somatosensory evoked responses were observed in 3 patients on stimulation of the side with choreic movements.