Middle Cerebral Artery Occlusion Presenting as Upper Limb Monochorea.

BACKGROUND: Hemichorea is usually caused by a structural lesion in the contralateral basal ganglia or subthalamic nuclei or it develops as a form of a neurologic complication including hyperglycemia. We report a rare case of a patient who developed choreic movement in the right upper extremity associated with a contralateral middle cerebral artery (MCA) occlusion. METHODS: A 76-year-old man presented with chorea in the right upper limb, known as monochorea, which occurred after recovery from losing consciousness while standing. He was found to have idiopathic orthostatic hypotension. His diffusion-weighted magnetic resonance imaging did not show signal changes indicative of acute ischemic lesions. A left carotid artery angiogram showed occlusion of the left MCA. (123)I-N-isopropyl-4-iodoamphetamine single-photon emission computed tomography of the brain showed marked hypoperfusion in the left MCA territory. His cerebrovascular reserve capacity determined using acetazolamide was relatively decreased in this territory. This decrease in cerebrovascular reserve capacity, however, did not require surgical treatment, such as extracranial-intracranial bypass surgery. RESULTS: The recurrence of chorea was not observed after antiplatelet therapy and instruction on how to cope with orthostatic hypotension. CONCLUSIONS: It is considered that transient hemodynamic ischemia in the right basal ganglia-thalamocortical circuits because of the combination of MCA occlusion and hypotension was the underlying cause of the monochorea in this patient.Vascular imaging studies for early identification of occlusion or severe stenosis of cerebral major arteries should be carried out in patients acutely presenting with chorea, even in the absence of other clinical signs.