Moyamoya | Symptoms & Causes

What are the symptoms of moyamoya?

Children with moyamoya may have symptoms that are similar to a stroke, such as:

  • weakness on one side of the body
  • blurry or otherwise affected vision
  • slurred speech
  • headaches
  • seizures

These symptoms can either begin gradually and get better over time, or develop suddenly and persist.

Rarely, a child with moyamoya may have a brain hemorrhage (bleeding in the brain), though this occurs much more often in adults with moyamoya. Warning signs of a brain hemorrhage can include:

  • nausea
  • vomiting
  • fatigue and lethargy
  • changes in vision
  • severe headache
  • numbness in part of the body

You should seek medical treatment right away if your child has any of the warning signs above.

What causes moyamoya in children?

Because moyamoya is so rare, its causes are not fully understood. Experts believe that a variety of factors — ranging from genetic defects to traumatic injury — may trigger the condition. There may also be a genetic component. About seven percent of children with moyamoya are believed to have an inherited gene defect. However, in at least half of all known cases of moyamoya, the disease has no identifiable cause.

Moyamoya disease is slightly more common in girls than in boys, and somewhat more common in children of Asian descent than in other ethnic backgrounds.