Moyamoya syndrome presenting in an adult with Down syndrome: A case report with a literature review.

Moyamoya disease is an unusual occlusive cerebrovascular condition commonly seen in children, marked by stenosis of the internal carotid artery and circle of Willis, causing, cerebral ischemia. Moyamoya syndrome is a Moyamoya-like arteriopathy with risk factors including autoimmune disorders, thyroid disease, sickle cell disease, or Down syndrome. Trisomy 21 is a genetic disorder consistent with specific physical and behavioral characteristics, with intellectual impairment. We describe a rare case of Moyamoya syndrome manifesting as ischemic stroke in an adult with Down syndrome.