Another infrequent vascular problem in children is moyamoya disease. This syndrome was first seen in children of Japanese descent where the carotid arteries — two of the large feeding vessels to the brain — undergo an unexplained narrowing. Often, this causes stroke or other symptoms of insufficient blood flow to the brain, such as seizures or weakness. The brain responds by developing very small collateral vessels which can appear to resemble a "puff of smoke" on radiographic images. (Hence, the Japanese name moyamoya, which means puff of smoke.)
Usually children with moyamoya respond well to a low-risk surgery called pial synangiosis. During this procedure, neurosurgeons place an artery directly on the brain surface to give the brain additional blood flow. This artery is sewn to the brain and, over time, will develop collateral blood supply to the areas that are in need of additional blood.