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Understanding Moyamoya

Stroke graphic

It’s important to know that even with rare conditions like this, there’s always a way to manage risk. We must control the factors we can: diet, exercise and not smoking.

Diana Rojas-Soto, MD

Moyamoya is a rare vascular condition of the brain, and women are three times more likely to have it than men. This progressive condition causes the brain’s main artery–the carotid–to become very narrow, decreasing blood and oxygen flow. A new cluster of tiny blood vessels opens at the base of the brain to compensate for the decrease in blood supply, but these blood vessels are unstable. What results is an increased risk for a stroke called a TIA (transient ischemic attack) or aneurysm, which can lead to short-term or permanent brain injury.

Moyamoya is a Japanese term that means “puff of smoke,” which describes the blood vessel cluster’s appearance. While the cause of Moyamoya is not fully understood, there is a higher incidence in Japan, Korea and China than in Europe and North America. These cases seemingly have a genetic connection and patients are mostly young children and teens. In Japan, one in 300,000 people are diagnosed with Moyamoya disease–usually females younger than 20 (source, National Organization for Rare Disorders).

Patients not of East Asian descent are considered to have Moyamoya syndrome. Recently, there has been an increase in Moyamoya syndrome diagnoses of perimenopausal women in their 40s and 50s, leading to hormone-related research. Family history also plays a role–the Mayo Clinic states that a Moyamoya diagnosis in a family member increases the likelihood by 30 to 40 times.

“Preconditions can contribute to Moyamoya syndrome, and hypertension is number one,” explains Diana Rojas-Soto, MD, Neurology, Dartmouth-Hitchcock Medical Center. “High blood pressure, cholesterol and diabetes also cause blood vessel damage, so we usually find Moyamoya patients have at least one of these risk factors.”

Most people don’t know they have Moyamoya until they experience stroke-like symptoms, such as numbness on one side of the body, trouble speaking or vision issues. Some patients might have experienced worsening headaches beforehand.

“Lots of people get headaches. But if they become unusually debilitating and incremental in intensity and duration, the recommendation is to be checked by a physician,” says Rojas-Soto. “The only way to diagnose Moyamoya is with imaging, and MRI [magnetic resonance imaging] and contrast enhanced CT [computerized tomography] scans of the arteries are the most sensitive. Headache characteristics can demonstrate the need for an MRI.”

Once Moyamoya is diagnosed, providers can reduce the risk of stroke with medication and/or surgery. Aspirin can help reduce the risk of blood clot formation in the narrowed cluster vessels, and some patients may benefit from anti-seizure medication or headache-reducing medications. While there is no cure for Moyamoya, revascularization surgery can increase blood flow to the brain and has stroke prevention benefits.

“It’s important to know that even with rare conditions like this, there’s always a way to manage risk. We must control the factors we can: diet, exercise and not smoking. Treat cholesterol and blood pressure aggressively, and seek smoking cessation counseling if you’re a smoker,” Rojas-Soto recommends.

Read Samantha Houle's patient story about her Moyamoya diagnosis.

 

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