Moyamoya disease is a rare, progressive cerebrovascular disorder caused by blocked arteries at the base of the brain in an area called the basal ganglia. The name “moyamoya” means “puff of smoke” in Japanese and describes the look of the tangle of tiny vessels formed to compensate for the blockage.
Moyamoya disease was first described in Japan and is found in individuals around the world; its incidence is higher in Asian countries than in Europe or North America. The disease primarily affects children but it can also occur in adults. In children, the first symptom of Moyamoya disease is often stroke, or recurrent transient ischemic attacks (TIA, commonly referred to as “mini-strokes”), frequently accompanied by muscular weakness or paralysis affecting one side of the body.
Adults may also experience these symptoms that arise from blocked arteries, but more often experience a hemorrhagic stroke due to bleeding into the brain. Other symptoms may include:
- disturbed consciousness
- involuntary movements
- vision problems
- cognitive and/or sensory impairment.
Some individuals with Moyamoya disease have a close relative who is also affected; in these cases researchers think that Moyamoya disease is the result of inherited genetic abnormalities. Studies that look for the abnormal gene(s) may help reveal the biomechanisms that cause the disorder.
Without surgery, the majority of individuals with Moyamoya disease will experience mental decline and multiple strokes because of the progressive narrowing of arteries. Without treatment, Moyamoya disease can be fatal as the result of intracerebral hemorrhage (bleeding within the brain).
Medications may be prescribed to reduce the risk of stroke. Several types of surgery can restore blood flow (revascularization) to the brain by opening narrowed blood vessels or by bypassing blocked arteries. Children usually respond better to revascularization surgery than adults. Some individuals have no further strokes or related problems after surgery.