Moyamoya disease is an increasing and chronic artery disease of the brain. The constriction of these blood vessels in people with moyamoya disease causes blockages, leading to ischemic stroke, hemorrhagic stroke, and seizures. The Japanese word “moyamoya” means “puff of smoke,” referring to the tangle of tiny vessels that evolved to compensate for the blockage. Moyamoya illness was first discovered in Japan and is now prevalent in people worldwide; it is more prevalent in Asia than in North America and Europe. The disease is most common in children, although it can also affect adults.