In this condition, small blood vessels also form a network of "side roads" trying to supply oxygen to the oxygen-deprived areas of the brain. These many tiny blood vessels show up clearly on an angiogram, which explains the name for the disease; in Japanese, "moyamoya"; means puff of smoke.
The male/female ratio of those with Moyamoya is 1:1.8, meaning that there is a female dominance. About 400 new patients are diagnosed annually in Japan, but while Moyamoya disease is noted everywhere in the world it is fairly common in East Asia and, above all, in Japan.
The origin is still not known. At present, it is speculated that its origin is both hereditary and acquired, in which case genetic factors as well as environmental factors may play an important role in the presentation of Moyamoya disease. Neither bacteria or virus are the cause of moyamoya, thus there is no chance of transmission of the disease from one to another.
(Picture provided by DJ at www.moyamoya.com)
