Moyamoya Disease | Symptoms and Causes

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What are the symptoms of moyamoya disease?

Children with moyamoya disease usually show symptoms consistent with a stroke, such as:

  • weakness on one side of the body
  • blurry or otherwise affected vision
  • slurred speech
  • headaches
  • seizures, especially when they occur in a child with no prior history of a seizure disorder

These symptoms can either emerge gradually and subside over time, or develop suddenly and persist.

Rarely, a child with moyamoya may have a brain hemorrhage — bleeding in the brain —but hemorrhaging is much more likely to occur in adults with moyamoya disease. 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 immediate medical treatment if your child exhibits any of the above warning signs.

What causes moyamoya disease in children?

Because moyamoya disease is so rare, and information about the progression the disease is limited, its causes are still not fully understood. Experts believe that a variety of factors — ranging from genetic defects to traumatic injury — may trigger the narrowing process in the brain’s carotid arteries. However, in at least half of all known cases of moyamoya, the disease has no identifiable cause.

Gender and ethnicity factors

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.

Genetic factors

About 7 percent of children with moyamoya disease are believed to have an inherited gene defect.

Associated disorders

Some children with moyamoya disease also have another condition, such as:

This suggests that an inherited, defective blood vessel structure may be linked to moyamoya.

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