Moyamoya Disease

What is Moyamoya Disease?

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 in the 1960’s and it 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.   In children, the first symptom of Moyamoya disease is often stroke, or recurrent transient ischaemic 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 haemorrhagic stroke due to recurring blood clots in the affected brain vessels.   Individuals with this disorder may have disturbed consciousness, speech deficits (usually aphasia), sensory and cognitive impairments, involuntary movements, and vision problems.  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 biomechanisms that cause the disorder.

Is there any treatment?

There are several types of revascularization surgery that can restore blood flow to the brain by opening narrowed blood vessels or by bypassing blocked arteries.  Children usually respond better to revascularization surgery than adults, but the majority of individuals have no further strokes or related problems after surgery. 

What is the prognosis?

Without surgery, the majority of individuals with Moyamoya disease will experience mental decline and multiple strokes because of the progressive narrowing of arteries.  Death usually results from intracerebral haemorrhage.