Moyamoya Disease

Moyamoya disease is a chronic, rare disease of the brain’s blood vessels. It causes the brain’s arteries to shrink. It usually worsens over time, happens on both sides of the brain and involves internal carotid arteries.

As the main arteries continue to narrow, small blood vessels form to carry the required amount of blood to the brain. These small vessels create a tangled, wispy shape that looks like a puff of smoke on an angiogram. This is why the disease is known by the Japanese word “moyamoya,” meaning “puff of smoke.”

Moyamoya disease is very rare. Only a few hundred children are diagnosed worldwide each year. Children are commonly diagnosed between ages 5 and 15.

For most children, there is no known cause. For others, it might be caused by:

  • Radiation
  • Sickle cell disease
  • Neurofibromatosis
  • Down syndrome


Symptoms of Moyamoya disease include strokes, headaches and cognitive or learning impairment. In children with Moyamoya disease, stroke occurs when the blood supply to the brain is blocked or severely reduced.

Call 911 or go to the nearest emergency department right away if you believe your child is having a stroke.

The blood flow may remain blocked, or the blockage may come and go quickly. This is called a transient-ischemic attack (TIA).
Some stroke symptoms include:

  • Weakness or numbness, especially on one side of the body
  • Trouble walking, speaking or seeing
  • Confusion
  • Seizures


At Children’s, our neurosurgery team provides a unique treatment plan for your child. For most patients, a surgical procedure called encephalo-dural-arterio-synagoiosis (EDAS) is effective. The surgery involves taking a normal blood vessel that typically supplies the scalp and placing it into the brain. This helps the brain to receive the supply of blood it needs.

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