What is the cause of moyamoya disease?
The cause of moyamoya disease is unknown. The process of narrowing of the brain arteries seems to be a non-specific reaction of the brain’s blood vessels to a wide variety of stimuli, injuries, or genetic defects. For example, in the more than 300 patients in the operative series of my colleague Edward Smith and myself seen from 1985 to the present, the disease has been associated with neurofibromatosis — the congenital condition that cases tumors to grow on nerves — in 24 patients, with Asian ancestry in 28, with Down Syndrome (a chromosome defect) in 22 children, in hematologic disorders like sickle cell disease in 12, etc. There is also an association with a previous history of surgery for congenital heart disease (14 patients), suggesting that there may be a genetic defect in blood vessel structure in these patients. But around 50% of our children have no known cause for their moyamoya disease. Our adult patients have usually had no definite cause detected either, but there have