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What is Moyamoya Disease?

Moyamoya disease is a rare condition, affecting only about one in a million people, in which certain arteries at the base of the brain are constricted and blood flow in the brain is blocked. The cause of the constriction is unknown, but does not appear to be due to atherosclerosis or inflammation.

The name “moyamoya” means “something hazy like a puff of smoke” in Japanese and describes the look of the tangle of tiny vessels formed to compensate for the blockage. Moyamoya disease was first described in Japan in the 1960s, and it has since been found in individuals all over the world. The disease primarily affects children, but it can also occur in adults.


In children, the first symptom of Moyamoya disease is often stroke , recurrent transient ischemic attacks (TIA, commonly referred to as “mini-strokes”), which are frequently accompanied by muscular weakness or paralysis affecting one side of the body, or seizures. Children may also have headaches and cognitive decline.


Diagnosis is usually possible with a magnetic resonance imaging (MRI) scan to look at the brain and a magnetic resonance angiogram (MRA) to look at the blood vessels of the brain. Sometimes, a conventional cerebral angiogram (also called arteriogram),  a special test in which a neuroradiologist injects dye into the blood vessels in the brain and obtains images of the blood vessels, is necessary to confirm the diagnosis. An angiogram is always needed for consideration of surgery.


Aspirin may help increase blood flow to the brain and is typically recommended. However, if your child has Moyamoya disease, the pediatric neurosurgeon may perform surgery to restore blood supply to the brain. There are several types of revascularization surgery available at Johns Hopkins:

  • Microsurgical pial synangiosis – during this procedure, we connect a blood vessel from the scalp to the surface of the brain and thus increase the blood supply to the brain.
  • Microsurgical extracranial-to-intracranial (EC-IC) bypass surgery – during this procedure, we connect an artery that typically supplies blood to the scalp to an artery in the brain and thus increase the blood supply to the brain.
  • Microsurgical encephaloduromyosynangiosis (EDMS) – during this procedure, we transfer the blood supply of a muscle under the scalp to the brain.
  • Microsurgical encephaloduroarteriosynangiosis (EDAS) – during this procedure, we transfer the blood supply of the scalp directly to the brain.

Johns Hopkins is one of the few hospitals in the country that carries out these microsurgical revascularization procedures with a high success rate.  To learn more about treatment for Moyamoya disease, or to make an appointment, please call 410-502-7700.

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Maryland Patients

For pediatric stroke and intracerebral hemorrhage:
Phone: 410-955-4259
Fax: 410-614-2297

For aneurysms and vascular malformations:
Phone: 410-955-8525
Fax: 410-614-8238

Adult Neurology: 410-955-9441
Pediatric Neurology: 410-955-4259
Adult Neurosurgery: 410-955-6406
Pediatric Neurosurgery: 410-955-7337


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