A case of Moyamoya disease in a girl with thyrotoxicosis.

Moyamoya disease is a cerebrovascular disorder of unknown cause, characterized by slowly progressive bilateral stenosis or occlusion of the internal carotid arteries and produces collateral vessels. Moyamoya syndrome has rarely been reported in association with Graves' disease, especially in children. Several reports suggest that a cerebral infarction might have occurred in patients with clinical and laboratory evidence of hyperthyroid function. We report a case of Moyamoya disease in a girl with Down syndrome and thyrotoxicosis, and we review the relevant literature. To our best knowledge, this is the first report of Moyamoya disease associated with thyrotoxicosis in a young person in Korea.