What Is Moyamoya Disease?

A stroke that results in one side of your body being paralyzed, seizures and/or muscular weakness could all be symptoms of Moyamoya disease. However, what causes this condition and who’s at risk?

Moyamoya disease is described as a “rare, progressive cerebrovascular disorder caused by blocked arteries at the base of the brain in an area called the basal ganglia,” according to the National Institute of Neurological Disorders and Stroke (NINDS). Although it is found in people from all around the world, there is a higher incidence of the condition in Asian countries. Additionally, the disease is more prevalent in children, but it can also be diagnosed in adults.

The first symptom of Moyamoya can be a stroke, along with paralysis on one side of the body and muscular weakness. The condition can be fatal if left untreated, according to NINDS.

So, what are the risk factors for Moyamoya disease and how effective are the treatment options available? An expert from USC Neurosciences at Keck Medicine of USC offers more information on this rare condition.

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What are the symptoms of Moyamoya disease?

The first symptom of Moyamoya disease in children is usually a stroke that comes on without warning. A child also may experience recurrent transient ischemic attacks (TIA), also referred to as mini strokes. Paralysis on one side of the body, seizures or muscular weakness may also accompany the initial stroke or mini strokes.

“Most of the time, people will present with stroke-like symptoms,” says Jonathan J. Russin, MD, a neurosurgeon at Keck Medicine and an assistant professor of clinical neurological surgery at the Keck School of Medicine of USC. “You tend to see strokes that are ischemic, where the blood flow doesn’t meet the demand.”

“They usually have initially reversible symptoms, where people will have weakness in one arm that gets better over a couple of minutes,” Russin says. “They sit down, they relax, and the brain can sort of auto-regulate. And then you can have, if they don’t listen to it … a pretty big stroke in an important area.”

Adults with Moyamoya disease are more likely to experience a hemorrhagic stroke due to bleeding in the brain from abnormal brain vessels, but they may also have TIAs.

“The brain is very dynamic. It’ll start to grow new blood vessels to try and get blood where it needs to go. And the new blood vessels are abnormal,” details Russin, who also works at the Cerebral Revascularization Center of USC, where Moyamoya disease is treated.

“The vessels themselves are somewhat sick, and they’re under a lot of pressure, quickly, to try and get blood moving, and you get little micro aneurysms on them, and they can burst. So you can present relatively quickly with bleeding in the brain.”

Other symptoms include vision problems, problems speaking and understanding speech, and sensory and cognitive impairments.

Who is at risk for Moyamoya disease?

Asians and those of Asian descent are more likely to have Moyamoya disease than other ethnic groups. The condition also may be the result of a gene abnormality; about one in 10 people with the disease have a close relative who also has it. It occurs twice as frequently in women than in men. Symptoms most often appear in children around the age of 5 or adults in their 30s or 40s.

How is Moyamoya disease diagnosed?

Moyamoya disease typically is diagnosed by MRI and, if necessary, a follow-up angiogram.

“Almost always, when you have a stroke, you have to look at the blood vessels,” Russin says. “And then the blood vessels, the pattern of stenosis and changes in the brain are very characteristic with Moyamoya. So you can pick it up generally on an angiogram or CT scan.”

How is Moyamoya disease treated?

There are many different surgical treatments for Moyamoya disease, all designed to improve blood flow to your brain. In bypass surgery, scalp arteries are attached to brain arteries, or your doctor may attempt revascularization to widen the damaged blood vessels. Treatment is generally very successful, and most who undergo treatment do not experience any more strokes or other symptoms associated with Moyamoya disease, according to NINDS.

by Anne Fritz

Are you experiencing symptoms of Moyamoya disease? The neurosurgeons at the Cerebral Revascularization Center of USC can help. If you are in the Los Angeles area, request an appointment or call (800) USC-CARE (800-872-2273).