4 questions parents have about moyamoya disease

moyamoya disease questions and answers

Last month, families from across the country gathered at Boston Children’s Hospital to celebrate World Moyamoya Day. The expert speakers at the Moyamoya Family Day Symposium shared the latest information about this rare but very serious condition with parents and patients alike.

Moyamoya disease occurs when the walls of the internal carotid arteries — the vessels that supply blood to important areas of the brain — become thickened and narrowed. As a result, blood flow to the brain slows, making blood clots more likely. Kids with moyamoya disease are at significantly higher risk of having a stroke, as well as other complications such as seizures and cognitive problems.

“Most parents have never heard of moyamoya until their child is diagnosed with it,” says Dr. Edward Smith, of the hospital’s Moyamoya Disease Program. “It’s natural to have a lot of questions and concerns.” Here are four of the questions he and his colleagues are asked most often.

What causes moyamoya disease?

Because moyamoya disease is so rare, there’s still much we don’t know about this condition. But ongoing research is shedding light on some of the factors potentially involved in its development, from radiation-related injury to genetics. About 7 percent of children with moyamoya disease appear to have an inherited defect in a gene called RNF213. Some kids with moyamoya also have other conditions — such as Down syndrome, sickle cell disease and neurofibromatosis — which suggests a genetic link, too.

What are the surgical options?

There are two main types of surgery for moyamoya disease: direct and indirect. The goal of both approaches is to improve blood flow to your child’s brain and prevent stroke. Also known as superficial temporal to middle cerebral artery anastomosis, a direct arterial bypass is a procedure in which neurosurgeons join a blood vessel from the scalp directly to a vessel in the brain. This can improve blood flow, but can be difficult to perform in kids because the arteries in their scalp are often too small.

There are several different kinds of indirect surgery, but they all encourage and introduce new blood vessel growth to the brain. A type of indirect procedure called pial synangiosis was pioneered at Boston Children’s and remains a mainstay of moyamoya treatment. It involves placing an artery from your child’s scalp directly in contact with the brain. Over time, small new blood vessels begin to form in this area. Recent research shows that indirect surgical procedures such as pial syangiosis appear to be more effective in treating moyamoya disease in the long term, especially in kids.

What are the risks of treatment?

Based on more than 400 patients with moyamoya disease who have undergone pial synangiosis surgery at Boston Children’s, it’s estimated that about 95 percent of kids will have no problems with surgery, but a small number may experience a stroke associated with the operation. These strokes can range from mild transient ischemic attacks to more severe episodes.

New research by Dr. Smith and his colleagues suggests that more than half of children with moyamoya disease tend to have blood vessels called transdural collaterals in their brains. Transdural collaterals are associated with advanced disease and with a higher likelihood of post-surgery strokes.

How do kids with moyamoya disease do in the long term?

Although every child is different, kids who receive prompt, expert treatment for moyamoya disease can go on to live long and fulfilling lives.


Learn more about the Moyamoya Disease Program at Boston Children’s Hospital or call 617-919-1379 to request an appointment.