Moyamoya disease is a rare entity that results in progressive occlusion of the arteries of the circle of Willis. In adults, this most commonly leads to intraventricular hemorrhage and less frequently to symptoms of ischemia. Without treatment, there is progressive deterioration of neurologic function and re-hemorrhage. Direct superficial temporal artery to middle cerebral artery bypass is considered the treatment of choice, although it's efficacy, particularly for hemorrhagic disease, remains uncertain.