Moyamoya disease affects an area of the brain called the basal ganglia, which is a group of nuclei deep in the white matter of the cerebral cortex. These nuclei control basic functions and transmit signals to and from one another.

With Moyamoya, the arteries of the basal ganglia become blocked. The name given to the disease means “puff of smoke” in Japanese based on the tangle of tiny vessels that form to try and go around the blockage. The disease was first described in Japan in the 1960s, where it has the highest incidence, but has also been diagnosed in people in the United States, Europe, Australia, and Africa. With kids, the group this disease affects the most, it often manifests in mini-strokes that are followed by muscle weakness, being paralyzed on one side of the body, or seizures. Hemorrhagic strokes because of blood clots are the symptoms most adults first experience.

Other symptoms associated with Moyamoya are disturbed consciousness, aphasia (complete or partial difficulty in pronouncing or understanding written or spoken language), cognitive and sensory deficits, problems with vision, and not being able to control movement.

The disease does appear to run in families, but the genes involved are not known at this time. Immunological disorders, certain bacterial infections, blood disorders, congenital syndromes, and disease of blood vessels have been seen in association with Moyamoya disease.

To treat Moyamoya, surgery is needed to open up narrow blood vessels or bypass the arteries that are blocked. Children tend to respond well to this type of surgery, but the problems associated with this disease disappear in both children and adults after surgery. Without surgery, the arteries will continue to narrow, which will cause mental decline and multiple strokes, and it can be fatal due to hemorrhage.