Moyamoya disease is characterized by chronic and progressive narrowing internal carotid arteries in the brain that can lead to complete blockage. To compensate for the narrowing arteries, the brain creates collateral blood vessels at the base of the brain in an attempt to facilitate the flow of oxygen-rich blood. The Japanese were the first to describe the condition. They named it “moyamoya,” the Japanese term for “puff of smoke,” because of the blood vessels’ hazy, filmy appearance on an angiography scan.
Most prevalent in Japan, fewer than one in 100,000 people in the U.S. are at risk of developing the disease. In adults, the disease can first appear with an ischemic stroke or transient ischemic attack (TIA), a blockage that interrupts the flow of oxygen-carrying blood to the brain, or with a hemorrhagic (bleeding) stroke.
Signs and Symptoms
Signs and symptoms of moyamoya are similar to those of ischemic stroke, hemorrhagic stroke or TIA and include: muscle weakness or partial paralysis on one side of the body, speech disturbance, sensory impairment, involuntary movement, and/or visual impairment.
A brain MRI is used determine the patient’s stroke history, followed by a CT angiogram or conventional cerebral angiogram to identify the characteristic arterial narrowing and collateral blood vessels associated with moyamoya disease.
There is no known medication that can reverse the progression of moyamoya disease. Surgery is generally recommended to treat patients with recurrent or progressive ischemic strokes or TIAs and involves directly connecting a donor artery to a recipient artery in the brain.
Revascularization through bypass surgery prevents further brain injury by using the external carotid circulation to increase collateral blood flow to underserved areas of the brain. Often, blood vessels are directly connected by a bypass to link the superficial temporal artery (STA) to the middle cerebral artery.