Moyamoya disease is the narrowing and ultimate closure of the internal carotid arteries, the two largest arteries feeding the brain. It is progressive and the vessel walls will continue to narrow over time. In response to the narrowing of the blood vessels, the body begins to grow many small blood vessels to bypass the blockage.

The word moyamoya means “puff of smoke” in Japanese and refers to the appearance of these networks of new blood vessels on an angiogram. The condition was first identified in Japan, where its incidence is higher than elsewhere.

Moyamoya disease affects mostly children and adolescents. While genetics are likely a factor in moyamoya disease, the cause remains unknown.

Moyamoya Syndrome

The narrowing of blood vessels at the base of the brain can also be associated with other diseases, and is referred to as moyamoya syndrome, which can be found in people with:

• Atherosclerotic disease or hardening of the arteries
• Down syndrome
• Neurofibromatosis
• Sickle cell anemia

Depending on its location, there are a variety of surgical techniques to treat moyamoya disease.

• Encephalo-duro-arterio-synangiosis (EDAS) involves placing an unaffected scalp artery directly on the brain and allowing connections (collaterals) to develop between the artery and the existing brain arteries, thus improving blood flow to the brain.
   
• Extracranial to intracranial (EC-IC) bypass creates a direct connection between a scalp artery and a brain (intracranial) artery.
   
• Encephalo-myo-synangiosis (EMS) uses muscle from the side of the head (temporalis muscle), which has a good blood supply, to accomplish the same purpose as EDAS.

If you are concerned about moyamoya disease, please call us for more information at (206) 341-0420.