Hemichorea improved by extracranial–intracranial bypass surgery for middle cerebral artery occlusion

Abstract

Hemichorea is often associated with structural ischemic lesions located in the motor frontosubcortical circuit of Alexander [1, 2]. However, the precise pathogenic link between the symptom and lesions remains uncertain [2, 3]. Recent reports have described patients with hemichorea caused by contralateral extraor intracranial arterial stenosis. Improvement of the hemichorea by surgical revascularizations and preand postsurgical single-photon emission computed tomography (SPECT) analyses suggested functional hypoperfusion, not a structural infarct per se, as an important etiology of hemichorea [4–8]. Here we report a case of hemichorea that improved following extracranial–intracranial (EC–IC) bypass surgery to treat hypoperfusion secondary to a middle cerebral artery (MCA) occlusion. A 67-year-old man acutely developed an involuntary movement in his left hand that spread to his left arm and leg within a few days. He had a smoking habit and hypercholesterolemia without any medication history including antipsychotics. The involuntary movement did not interfere with his daily activities and walking, but persisted for 2 months. Neurologic examination was unremarkable except for the hemichorea and mild leftsided facial dyskinesia. Hemiballism and other extrapyramidal signs were absent. The hemichorea was persistent and unrelated to the patient’s posture. Orthostatic hypotension was absent. Blood tests revealed hypercholesterolemia (LDL-cholesterol 192 mg/dl; the normal range 70–140 mg/dl). Antinuclear antibody, lupus anticoagulant activity, and anticardiolipin antibodies were absent. Thyroid function and plasma osmolarity were normal. Brain diffusion-weighted magnetic resonance imaging (MRI) showed no acute infarct (Fig. 1a, b). T2-weighted MRI revealed an old infarct in the right frontal white matter (Fig. 1c) but no lesion in the basal ganglia (Fig. 1d). Cerebral angiography revealed an occlusion at the stem of the right MCA (Fig. 1e). Collateral arterial networks linking the right anterior cerebral artery, posterior cerebral artery (PCA), and branches from the right external carotid arteries supplied the large part of the right cerebral hemisphere (Fig. 1f). The right deep cerebral structures were supplied by collaterals originated from the occluded MCA stem and the right PCA (Fig. 1e, f). No abnormal net-like collateral vessels (moyamoya vessels) were present (Fig. 1f), and atherosclerosis was postulated to be a cause of the MCA occlusion. SPECT using I-labeled N-isopropyl iodoamphetamine (I-IMP) suggested no basal hypoperfusion (Fig. 1g), but acetazolamide-challenged I-IMP SPECT revealed a decrease of vascular reserve [9] in the right MCA territory, including the right basal ganglia (Fig. 1h). The patient was treated with aspirin (300 mg daily), atorvastatin (20 mg daily), and cilostazol (200 mg daily), but the hemichorea persisted. Three months after onset, an EC–IC bypass (superficial temporal artery-MCA anastomosis) operation was performed. Surprisingly, the hemichorea improved a few days after the surgery. Follow-up SPECT 1 week after the surgery T. Irioka (&) Department of Neurology, Yokosuka Kyosai Hospital, 1-16 Yonegahama-dori, Yokosuka, Kanagawa 238-8558, Japan e-mail: t-irioka.neuro@ykh.gr.jp