Moyamoya Disease

Moyamoya disease (or syndrome) is a rare medical condition that progressively narrows the internal carotid arteries that carry blood to the brain. This limits the blood flow inside the skull and creates risk for stroke. The brain tries to make up for the decreased blood flow by creating many tiny, new blood vessels at the base of the brain. These new arteries are more fragile.

Moyamoya means “puff of smoke” in Japanese. It refers to the wispy, smoke-like appearance of these new blood vessels on a special x-ray test called a cerebral angiogram.

Moyamoya disease is most commonly seen in children, usually between the ages of 5–10, who present with stroke or recurring transient ischemic attacks (TIAs). Symptoms may be triggered by things like exercise, crying or straining. Moyamoya disease can also be seen in adults, usually between the ages of 30–50, who can experience stroke, TIAs or hemorrhagic stroke (brain bleed).

Signs and Symptoms

Moyamoya disease can affect one or both sides of the brain. The first sign is often a transient ischemic attack or a stroke. A brain hemorrhage is seen more often in adults who have moyamoya disease. Symptoms include:

  • Stroke or stroke-like symptoms (TIAs)
  • Weakness/paralysis or numbness on one side of the body may alternate with weakness or numbness on the other side of the body (when moyamoya changes affect both sides of the brain)
  • Vision problems
  • Involuntary movements
  • Seizures
  • Migraine-like headaches
  • Cognitive impairment and developmental delay in children

Potential Causes

The exact cause of moyamoya changes is not currently known. When it is seen in association with other medical conditions, it is referred to as moyamoya syndrome. Moyamoya syndrome can be seen with sickle cell disease, Down syndrome, neurofibromatosis type 1, congenital heart disease, thyroid disease (Graves’ disease) and connective tissue disorders such as Ehlers-Danlos and Marfan syndromes. It can also develop following radiation treatment for brain tumors such as craniopharyngioma, hypothalamic glioma and pineal tumors.

Moyamoya disease appears to show a pattern of inheritance in some families, indicating a genetic abnormality or injury. It is more common in East Asian populations in Korea, Japan and China. Females are affected more often than males.


If you show the type of signs and symptoms listed above, neurologists and neurosurgeons will perform specific tests to make an accurate diagnosis. The following exams and tests may be performed in the diagnosis of moyamoya disease (syndrome): computed tomography ( CT ) with CT angiography ( CTA ), magnetic resonance imaging ( MRI ) with MR angiography ( MRA ), MRI perfusion scan, transcranial doppler study (TCD), cerebral angiogram , positron emission tomography ( PET ) scan, single-photon emission computerized tomography ( SPECT ) scan or electroencephalogram ( EEG ).

Treatment Options

If diagnostic tests determine that moyamoya changes are present, you will be referred to a neurosurgeon to discuss your condition and work with you to create a plan for treatment. At Goodman Campbell, we have a select group of neurosurgeons who are experienced in managing this condition.

Moyamoya disease (syndrome) tends to progressively narrow and close the blood vessels. Treatment is needed to reduce the risk for stroke and other problems related to poor blood flow in the brain. Treatment options include:

  • Blood thinning medication Aspirin or other blood thinners may be used in patients who are mildly affected. It is used to help with blood flow and decrease the risk for stroke. Other medicines may be used to help with headaches or seizures.
  • Surgery The goal of surgery is to improve the blood flow to the brain in an effort to reduce the risk for stroke. Two types of surgical approaches are used for moyamoya changes.
    • Direct revascularization In this operation, a small artery from the scalp is directly connected to an artery on the surface of the brain. It is called an extracranial-to-intracranial (EC-IC) bypass. This provides an immediate increase to the blood flow in the area of the brain affected by the moyamoya changes.
    • Indirect revascularization In this set of operations, selected tissues are placed on the surface of the brain. Over time, new blood vessel connections grow over the brain surface. These procedures may be better for children who have small blood vessels, which makes the direct surgical connection between arteries technically difficult. These “indirect” procedures are also being used to treat adults. EDAS (encephalo-duro-arterio-synangiosis) lays a branch of one of the larger scalp arteries over the brain surface. EMS (encephalo-myo-synangiosis) places a strip of muscle from under the scalp over the surface of the brain. Sometimes, EDAS and EMS may be combined. Omental transfer places a piece of omentum (a fatty sheet over the abdominal organs which has a rich blood supply) over the brain surface. The omentum can be harvested by laparoscopic surgery. In some instances, a series of burr holes are made, and blood vessels from the tissue over the skull grow in to supply extra blood to the brain surface.
  • Moyamoya anesthesia protocol Individuals with moyamoya disease (syndrome) have an increased risk for stroke under routine anesthesia. In these cases, the anesthesiologists carefully monitor patients during surgery to maintain proper blood pressure, hydration and breathing rate to decrease this risk. Intraoperative EEG monitoring may also be used.

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