Until October 19, 2009 I had no idea such a thing as Moyamoya exists.
Moyamoya is a Japanese term that means "puff of smoke."
According to Children's Hospital Boston...
"Moyamoya disease is a very rare condition in which the walls of the internal carotid arteries - which supply blood to important areas of the brain - become thickened. This gradually slows the flow of blood to the brain and increases the likelihood of blood clot formation, both of which can lead to strokes and transient ischemic attacks.
In this condition, small blood vessels also form a network of "side roads" trying to supply oxygen to the oxygen-starved areas of the brain once served by the narrowed arteries. These many tiny blood vessels show up clearly on an angiogram, explaining the name for the disease; in Japanese, "moyamoya" means puff of smoke."
Apparently there are only a couple hundred cases diagnosed every year. This is a rare disease. The only viable treatment option is surgery. For children the most popular surgery performed for Moyamoya is pial synangiosis. Basically, a large artery from the outside of the head is attached to the brain which in turn, with time, creates new blood flow, essentially by-passing the un-healthy, lack of blood flow do to the disease.
Here are a few sites about Moyamoya:
Children's Hospital Boston
Moyamoya.com (a support network and wealth of information for people fighting this disease)
To read about Polly's stroke and diagnosis go HERE.