Moyamoya disease is a disorder characterized by narrowing of the intracranial internal carotid artery (ICA) and its branches, the middle cerebral and anterior cerebral arteries. Over time this results in a unique angiographic appearance of small abnormal blood vessels at the base of the brain that resemble a “puff of smoke”, which is the English translation of the Japanese word moyamoya. The condition was first identified in Japan and although initially felt to primarily effect the Asian population it is now recognized to be a worldwide disorder. As the disease progresses small aneurysms may form and the patient may experience a stroke or bleeding in the brain. Following diagnosis treatment is directed at increasing the blood supply to the brain, most commonly by performing a surgical procedure (direct or indirect bypass procedure).