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Moyamoya Disease

Moyamoya disease is a rare, progressive cerebrovascular disorder caused by blocked arteries at the base of the brain (Circle of Willis). The word “moyamoya” means “puff of smoke” in Japanese and is a description of the look of the tangle of tiny vessels that are formed to compensate for the blockage.  Moyamoya disease was first described in Japan in the 1960s and is most commonly seen in Japan and Asian countries. However, moyamoya has also been found in the United States, Europe, Australia and Africa. Moyamoya primarily affects children but it can also occur in adults.

The majority of individuals afflicted with moyamoya disease require some form of surgical intervention. Without this, many will suffer from multiple strokes and mental decline because of the progressive nature of the disease. Without treatment, moyamoya can be fatal if the result is an intracerebral hemorrhage.


Symptoms of moyamoya disease often include transient ischemic attacks (TIAs). Stroke is another possible symptom, which may include weakness of one side of the body or paralysis, visual changes, speech difficulties or seizures. Adults can more commonly experience a hemorrhagic stroke due to recurring blood clots in the affected brain vessels.


Diagnosis of this condition can include a review of symptoms and family and medical history, along with a neurological examination. It can also include specialized diagnostic testing to look more closely at underlying conditions, including:

  • Magnetic Resonance Imaging (MRI): An MRI uses powerful magnets and radio waves to create detailed images of the brain. Sometimes dye can be injected into a vein in the arm to highlight all blood vessels in the brain, which is called a Magnetic Resonance Angiogram (MRA).
  • Computerized Tomography scan (CT): A CT scan uses a series of X-rays to create a detailed image of the brain. Contrast dye may be injected into a blood vessel to highlight blood flow in the arteries and veins in the brain, which is call a CT angiogram.
  • Cerebral angiogram: A thin extremely flexible and soft tube, or catheter, is inserted into a blood vessel in the groin—the femoral artery—and navigated through the blood vessels using X-ray imaging. Dye may be injected through the catheter into the blood vessels of the head to make them visible under X-ray imaging. These images are today’s gold standard in blood vessel imaging.
  • DirectRevascularization

    Illustration of direct STA-MCA bypass

    Brain Single Photon Emission Computerized Tomography scan (SPECT): A SPECT scan is a nuclear imaging test that may be used to check the blood flow to the brain. This allows a doctor to see if certain areas of the brain are being deprived of blood flow.



Illustration of an indirect EDAS bypass

There are several types of treatment options available for moyamoya disease. They are geared to restore blood flow to the brain by opening narrowed blood vessels or by bypassing blocked arteries. The goal of treatment is to reduce symptoms, improve blood flow and lower risk of serious complications, such as strokes, bleeding in the brain, known as intracerebral hemorrhages, or death. There are several types of revascularization surgeries to treat moyamoya disease. Below are the more common treatment options:

Direct revascularization procedures: In these procedures, a surgeon attaches a superficial scalp artery (superficial temporal artery or STA) to a brain artery (middle cerebral artery or MCA) by suturing one vessel to the other. This creates a new immediate path of blood flow to the brain. This approach can be more difficult for children due to the small size of the vessels.

Indirect revascularization procedures: One common approach is called  encephaloduroarteriosynangiosis (EDAS).  The surgeon using will dissect a superficial scalp artery over several inches. Then, using a temporary opening in the skull, will attach (or suture) this superficial artery to the surface of the brain. This allows the artery to help form new blood vessels to grow into the brain over time.