What is Moyamoya Disease?

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  • Written By: Niki Foster
  • Edited By: Andrew Jones
  • Last Modified Date: 16 November 2018
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Moyamoya disease is a disorder in which blood flow in the brain is blocked due to the constriction of certain arteries. The affected blood vessels develop collateral circulation, or the formation of small blood vessels to circumnavigate the blockages. The newly formed blood vessels are weak, however, and are also subject to thrombosis and bleeding. Moyamoya disease takes its name from a Japanese word meaning "puff of cigarette smoke" as the small collateral vessels have the appearance of a puff of smoke on X-rays.

The internal carotid artery, a major blood vessel in the neck which supplies blood to the brain, is the structure most often affected by moyamoya disease. The disease can have effects into the fourth decade of the patients life. While affected children often experience seizure and stroke, the disease can manifest in adults as stroke, bleeding, migraine-like headaches, and numbness in the extremities. Moyamoya disease is more common in women than men, and typically becomes symptomatic in the third or fourth decade of life.

Moyamoya disease can sometimes be treated with antiplatelet medication, such as aspirin, which prevents clotting, but often, surgery is required. Surgical treatment creates new pathways in the blood vessels to avoid blocked passages. There is a four percent risk of stroke during the month after surgery, but a 96% chance of remaining stroke-free for five years.


Moyamoya disease is diagnosed through brain imaging techniques such as angiogram, computed tomography (CAT) scans, or magnetic resonance imaging (MRI). It is important to catch and treat the disease as early as possible, because permanent damage and even death can occur from a serious stroke. Surgically treated patients tend to have a good prognosis.

In addition to the direct bypass surgical approach, called STA-MCA because it attaches the superficial temporal artery (STA) to the middle cerebral artery (MCA), there are other surgeries for moyamoya disease that serve to promote the growth of new blood vessels, or the development of more efficient ways of bringing blood into the brain. Encephaloduroarteriosynangiosis (EDAS) sutures a scalp artery to the surface of the brain. Encephalomyosynangiosis (EMS) sutures the temporalis muscle of the scalp to the brain surface. Finally, in the multiple burrs procedure, numerous small holes are drilled into the skull to promote the growth of many small blood vessels into the brain from the scalp.



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