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​Moyamoya Disease (Moyamoya Syndrome)

What is Moyamoya Disease?

Moyamoya disease is the narrowing and ultimately closure of the internal carotid arteries, the two largest arteries feeding the brain. Moyamoya disease is progressive, meaning the vessel walls will continue to narrow over time.

The cause of moyamoya disease is unknown, although genetics are a likely factor. It affects mostly children and adolescents.

In response to the narrowing of the blood vessels, the body will begin to grow many small blood vessels to bypass the blockage.

The word moyamoya means “puff of smoke” in Japanese, and refers to the appearance of these networks of new blood vessels. The condition first was identified in Japan, where its incidence is higher than elsewhere.

Moyamoya syndrome

The findings of narrow blood vessels at the base of the brain can also be associated with other diseases, and is referred to as moyamoya syndrome. This syndrome can be found in people with:

UPMC offers a variety of surgical techniques to treat Moyamoya disease, depending upon the exact location of the disease.

Diagnosing Moyamoya Disease

Symptoms of Moyamoya disease

Because Moyamoya disease may be an inherited genetic abnormality, a doctor will also review the family history.

Signs and symptoms of Moyamoya disease may include:

  • Aphasia (loss of ability to use or comprehend words)
  • Blurred vision
  • Cognitive (reasoning or remembering) impairment
  • Convulsions
  • Involuntary movements
  • Numbness in arms and legs
  • Seizures
  • Severe headaches

Adults with Moyamoya disease also often experience hemorrhagic stroke (a burst blood vessel inside the brain).

Testing to diagnose Moyamoya disease

CT and MRI scans may provide initial indications of the disease. If the disease is suspected, cerebral angiography, a test that creates images of the blood flow through the brain, is conducted to establish the diagnosis.

UPMC is one of the few centers in the nation to have all major methods of measuring brain blood flow.

Moyamoya Disease Treatments

There is no evidence that medications slow the progression of Moyamoya disease. At UPMC, highly trained and experienced neurosurgeons use revascularization procedures to bypass narrowed or blocked arteries and restore blood supply to the brain.

Surgery and revascularization

Revascularization procedures performed at UPMC include:

  • External carotid to internal carotid (EC-IC) bypass: The doctor attaches one of the arteries in the scalp (superficial temporal artery) to one of the major arteries in the brain (middle cerebral artery).
  • EDAS (encephaloduroarteriosynangiosis): The doctor frees up, without severing, a scalp artery over a course of several inches and then makes a small temporary opening in the skull directly beneath the artery. The artery is then sutured to the surface of the brain and the bone replaced.
  • EMS (encephalomyosynangiosis): A muscle in the temple region of the forehead is dissected and placed onto the surface of the brain through an opening in the skull. Multiple burr holes are drilled into the skull to allow new blood vessels to grow.
  • STA-MCA (superficial temporal artery-middle cerebral artery) bypass: A scalp artery is directly sutured to a brain surface artery to bring blood directly to where the brain needs it most.

In rare circumstances, our endovascular team will evaluate the person for minimally invasive alternatives such as:

Without surgery, the majority of people with Moyamoya disease will experience mental decline and multiple strokes because of the progressive narrowing of the arteries. If untreated, Moyamoya disease can be fatal.


Neurosurgery at UPMC: A powerful team approach
Dr. Robert M. Friedlander discusses the team approach to treating neurosurgical patients.

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