Elderly-Onset Moyamoya Disease Presenting with Hemichorea Associated with Basal Ganglia Hyperperfusion: Symptomatic Improvement after Revascularization Surgery.

INTRODUCTION: Chorea has been reported in pediatric moyamoya disease, which is commonly associated with ischemia of the basal ganglia. However, elderly patients are rare, and the underlying mechanisms remain unclear. CASE PRESENTATION: A 69-year-old woman presented with a 6-month history of involuntary hemichorea affecting her left upper and lower limbs. Magnetic resonance imaging showed no acute infarction but demonstrated right middle cerebral artery (MCA) occlusion. Digital subtraction angiography revealed moyamoya collateralization. The 123I-iodoamphetamine single-photon emission computed tomography scan revealed increased perfusion of basal ganglia and impaired cerebrovascular reserve in the right MCA territory. The patient underwent right superficial temporal artery-MCA bypass combined with encephalo-duro-myo-synangiosis. Postoperatively, basal ganglia hyperperfusion persisted, but cerebrovascular reserve improved. Her hemichorea markedly subsided, and she was discharged without neurological deficits. This is one of the oldest reported cases of moyamoya syndrome presenting with hemichorea. CONCLUSION: Our findings suggest that chorea associated with moyamoya disease may result not only from decreased, but also from imbalanced basal ganglia perfusion. Revascularization surgery may help restore this balance and alleviate symptoms, even in elderly patients.