Moyamoya disease is a rare condition that affects the blood vessels in your brain. It can lead to brain bleeds and strokes in affected areas of your brain. There’s no cure for moyamoya disease. Treatment typically involves managing symptoms and preventing blood clots with medications. You may also need surgical bypass to supply more arteries to your brain for adequate blood flow.
Moyamoya disease affects the blood vessels in your brain. It's a cerebrovascular disease. In moyamoya disease, at least one carotid artery — and sometimes both — narrows or closes. Additionally, the front and/or middle cerebral arteries can be blocked. These key arteries deliver blood and oxygen to the front two-thirds of your brain. Over time, your brain forms new blood vessels to make up for the blood and oxygen lost from the blockage. But since these blood vessels are formed as emergency backup vessels, they're smaller and often weaker than the blocked artery. These smaller, backup arteries often can't supply enough blood to your brain. This may lead to brain bleeds and strokes in affected areas of your brain.
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“Moyamoya” is a Japanese word that means “puff of smoke.” Japanese doctors discovered that when they did blood vessel scans called angiograms in operating rooms on these patients, the smaller backup vessels looked like a curled up “puff of smoke” when they injected iodine contrast into their blood vessels. That's why they used the term “moyamoya disease” to describe it.
Moyamoya disease is rare. Although the genetic forms occur mostly in patients of Asian ancestry, healthcare providers see it more and more in patients from other ethnic backgrounds.
For reasons that scientists don’t understand, moyamoya disease is two times more common in people assigned female at birth than in people assigned male at birth.
There are two age ranges when moyamoya occurs more often: around 5 to 10 years old and between 30 and 50 years old. But it can happen at any age.
The exact cause of moyamoya disease remains unknown. But there appear to be genetic and acquired forms. Researchers are still exploring genes that could possibly get passed down from parents.
Sometimes moyamoya disease occurs with other conditions and is called moyamoya syndrome or phenomenon. Examples of these other conditions include:
The first sign of moyamoya disease is often stroke or repeated transient ischemic attacks (TIAs). Providers call these “mini-strokes.” Other symptoms may include:
If a healthcare provider suspects moyamoya disease, you may need the following tests:
There's no cure for moyamoya disease, but it's treatable.
If you’re diagnosed with moyamoya disease, your healthcare provider may suggest certain medications:
Medications can’t stop blood vessels from narrowing, so moyamoya disease may continue to worsen. Your healthcare provider may then consider bypass surgery that:
There's no proven way to prevent genetic forms of moyamoya disease. But you can lower your risk of developing moyamoya syndrome by controlling vascular risk factors and reducing your risk of atherosclerosis.
You may be able to relieve symptoms and avoid complications from moyamoya disease if you make sure you take your medications exactly as directed.
For most people with moyamoya disease, the condition gets worse over time. They may also experience strokes as blood vessels narrow more and more. Without treatment, moyamoya disease can lead to stroke with severe neurological deficits. However, some patients remain stable for years without symptoms. Once symptoms start to develop, your provider may suggest bypass surgery.
Get immediate medical attention if you experience any signs of a stroke.
The American Stroke Association uses the acronym F.A.S.T. to help people remember how to react:
Other symptoms of stroke include sudden:
A note from Cleveland Clinic
Moyamoya disease is a rare condition that can lead to ischemic strokes and brain bleeds. Talk to your healthcare provider if you’re having any of the symptoms mentioned above. Learn how to recognize the signs of stroke, which need immediate medical attention.
Last reviewed by a Cleveland Clinic medical professional on 05/06/2021.
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