Hemichorea and hemiballism associated with contralateral hemiparesis and ipsilateral basal ganglia lesions

We report on two patients with unilateral hyperkinetic movement disorders a ssociated with contralateral hemiparesis and ipsilateral basal ganglia lesi ons. The first patient, a 47-year-old woman, had a low-grade astrocytoma lo cated in the right basal ganglia extending into the subthalamic area and th e cerebral peduncle. She presented with left hemiparesis, right hemichorea, and intermittent right-sided tremor at rest. The second patient, a 85-year -old woman, had hypertensive hemorrhage to the right posterior basal gangli a, the posterior limb of the internal capsule, the lateral thalamus, and th e subthalamic region with accompanying intraventricular bleeding. She devel oped right-sided transient hemichorea-hemiballism. A videotape illustration of one of the patients is provided. The literature on the rare occurrence of ipsilateral hemichorea-hemiballism is discussed and possible pathomechan isms are reviewed. We postulate that hemiparesis contralateral to basal gan glia lesions might have a conditioning effect on the appearance of ipsilate ral dyskinetic movement disorders.