A rare inherited vascular disorder characterized by constriction of arteries at the base of the brain, resulting in the formation of collateral circulation in order to compensate for the constriction. the name "moyamoya" in japanese means "puff of smoke" and derives from the characteristic radiographic appearance of the collateral vessels.

Moyamoya disease is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by constriction and blood clots (thrombosis)...