Moyamoya disease is a rare, progressive cerebrovascular disorder. 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.
It was first described in Japan in the 1960s and has since been found in individuals in the United States, Europe, Australia and Africa. The disease primarily affects children, but it can also occur in adults.
Moyamoya disease is caused by gradually blocked large arteries at the base of the brain in an area called the circle of Willis. Because it tends to run in families, researchers think that moyamoya disease is the result of inherited genetic abnormalities. Studies that look for the abnormal gene(s) may help reveal the pathophysiology that causes the disorder.
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, or seizures.
Adults most often experience a hemorrhagic stroke due to recurring hemorrhage from the affected brain vessels.
There are several types of revascularization surgery that can restore blood flow to the brain by providing new collateral blood supply either directly or indirectly. Direct blood supply can be provided by anastomosing a scalp artery to a cerebral branch (STA-MCA). Indirect techniques can involve placing dura and muscle on the brain surface which then grows new connections to the brain. Children usually respond better to revascularization surgery than adults, but the majority of individuals have no further strokes or related problems after surgery.
Individuals with this disorder may have disturbed consciousness, speech deficits (usually aphasia), sensory and cognitive impairments, involuntary movements and vision problems.