Moyamoya disease was first described in 1957 in Japan and is more prevalent in Asian cultures. Annually, moyamoya will affect anywhere from 0.35 to 0.94 per 100,000 people. Generally, moyamoya is thought to have a “bimodal” distribution whereby it mainly affects people either in their first (childhood moyamoya) or fourth decades of life (adult moyamoya). Moreover, it is associated with 6% of childhood strokes and carries a 10% occurrence between family members. As such, genetic inheritance may play a role in the disease.
It is characterized by the narrowing of the internal carotid arteries which constitute a significant source of blood flow to the brain. With age, this reduction of blood flow to the brain leads to establishment of a series of smaller blood vessels (“moyamoya vessels”) at the base of the brain to provide alternate circulation to the brain. Moyamoya vessels are at risk of rupturing and so adult moyamoya is often characterized by bleeding into the brain. Childhood moyamoya is characterized by a lack of blood flow to brain tissues, resulting in strokes. However, both strokes and hemorrhages can occur in children and adults.
There is no one optimal treatment for moyamoya. Generally, drug therapy with corticosteroids, calcium-channel blockers, blood thinners, and vasodilators has had some success. Surgical options are largely referred to as “revascularization” procedures whereby the narrowing or blockage of the internal carotid arteries due to moyamoya is bypassed. Treatment will depend on your particular case and will be determined by your doctor.
George Goshua and Justin F. Fraser, MD
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