Moyamoya disease is a rare blood vessel (vascular) disorder in which a ring of blood vessels at the base of your brain (the circle of Willis) progressively narrows, causing blood flow to your brain to become blocked. The condition may cause a ministroke (transient ischemic attack), stroke or other symptoms.
Moyamoya disease mainly affects children, but adults also may have the condition. Moyamoya disease usually occurs in people from Japan and other Asian countries, but people in the United States, Europe, Australia and Africa also have been diagnosed with Moyamoya disease.
Nov. 19, 2012