Moyamoya Disease

What is Moyamoya disease?

Moyamoya disease is a type of cerebrovascular disease — a condition that affects the blood vessels in your brain. In moyamoya disease, at least one of your carotid arteries — and sometimes both — narrow or close. It also affects your front and/or middle cerebral arteries. These key arteries deliver blood and oxygen to the front two-thirds of your brain. When these blood vessels narrow, it blocks blood flow to your brain.

Over time, your brain forms new blood vessels to make up for the blood and oxygen lost from the blockage. But as these blood vessels are formed as emergency backup vessels, they’re smaller and often weaker than the blocked arteries. These smaller, backup arteries often can’t supply enough blood to your brain. This may lead to brain bleeds and stroke in the affected areas of your brain.

What does moyamoya mean?

“Moyamoya” is a Japanese word that means “puff of smoke.” Japanese doctors discovered that the smaller backup vessels looked like curled-up puffs of smoke when they did blood vessel scans called angiograms. That’s why they used the term “moyamoya disease” to describe the condition.

How rare is moyamoya disease?

Moyamoya disease is most common in Japan, where it affects about 5 in every 100,000 people. In the United States, the condition affects fewer than 5,000 people.

What are the symptoms of moyamoya disease?

A lack of blood supply to your brain can lead to the symptoms of the disease. The first sign of moyamoya disease is often stroke or repeated transient ischemic attacks (TIAs). Healthcare providers may call these “mini-strokes.” Other moyamoya disease symptoms may include:

• Brain hemorrhage (bleeding).
• Headaches.
• Developmental delays.
• Aneurysm (bulging or ballooning of a blood vessel, which can burst).
• Involuntary movements (when your body parts move without your control).
• Problems with cognitive abilities (like learning, remembering and paying attention).
• Problems with your senses (sight, hearing, smell, touch and/or taste).
• Seizures.

What causes moyamoya disease?

Researchers don’t know the exact causes of moyamoya disease. But there appear to be genetic and acquired forms of the condition. Researchers are still exploring genes that could get passed down from biological parents. There may be other factors, like inflammation or infection, that could cause the condition, too.

Sometimes, moyamoya disease occurs with other conditions and is called moyamoya syndrome or phenomenon. Examples of these other conditions include:

• Down syndrome.
• Graves’ disease.
• Neurofibromatosis type 1.
• Sickle cell disease.
• Atherosclerosis.

Is moyamoya disease genetic?

Researchers have discovered mutations, or changes, in one gene — RNF213 — that may be responsible for at least some cases of moyamoya disease. The RNF213 gene is responsible for producing a protein that may be involved in the development of blood vessels.

As many as 15% of people of Japanese descent with moyamoya disease have one or more biological family members with the condition. That’s a sign that the condition is likely genetic, but the inheritance pattern is unknown.

Who gets moyamoya disease?

Moyamoya disease is rare. Although the genetic forms occur mostly in people of Japanese ancestry, healthcare providers see it more and more in people from other ethnic backgrounds.

For reasons that scientists don’t understand, moyamoya disease is two times more common in women and people assigned female at birth (AFAB) than in men and people assigned male at birth (AMAB).

You can get moyamoya disease at any age, but you’re more likely to get it if you’re between five and 10 years old or between 30 and 50 years old.

What are the complications of this condition?

Complications of moyamoya disease may include:

• Paralysis.
• Vision problems.
• Speech problems.
• Movement disorders.
• Brain damage.

How do you know if you have moyamoya disease?

A healthcare provider will perform a physical examination and ask you about your symptoms. If they suspect moyamoya disease, you may need the following tests:

• Cerebral arteriography: Your provider inserts a small tube called a catheter into an artery in your arm or leg. They then use it to inject iodine contrast dye into your bloodstream. Next, they take X-ray scans of the dye in your blood vessels. This technique can reveal how much your blood vessels have narrowed and map blood flow patterns.
• Magnetic resonance angiography (MRA): In this pain-free test, your provider uses a magnetic field, radio waves and a computer to look at your blood vessels.
• Magnetic resonance imaging (MRI): MRI uses similar technology to take pictures inside your body and can help assess the effect of moyamoya disease on your brain.

What are the stages of moyamoya disease?

Moyamoya disease is progressive. That means it will gradually get worse without treatment. Healthcare providers use the “Suzuki” stages to describe the severity of the disease. They’ll use the MRA test to help determine what stage of the disease you’re in. Suzuki stages include:

• Stage 1 — Narrowing of carotid fork: The narrowing or blockage is only affecting the internal part of your carotid artery.
• Stage 2 — Initiation and appearance of basal moyamoya vessels: The narrowing is affecting all the terminal branches of your internal carotid artery, and deep moyamoya blood vessels are starting to become visible on the angiogram.
• Stage 3 — Intensification of basal moyamoya vessels: The deep moyamoya blood vessels are intensified on the angiogram, and the “puff of smoke” appearance can be seen.
• Stage 4 — Minimization of basal moyamoya vessels: On the angiogram, the deep moyamoya blood vessels start to regress. Other blood vessels called transdural collateral vessels start to appear.
• Stage 5 — Reduction of moyamoya vessels: On the angiogram, the deep moyamoya blood vessels continue to regress, and more transdural collateral vessels begin to appear.
• Stage 6 — Disappearance of moyamoya vessels: All the deep moyamoya blood vessels have vanished, and there’s a complete narrowing or blockage of the internal carotid artery.

What is the treatment for moyamoya disease?

Moyamoya disease treatment involves managing your symptoms with certain medications. Your healthcare provider may recommend or prescribe medications like:

• Aspirin: Aspirin can help prevent or reduce blood clots in the smaller, backup blood vessels that develop.
• Antiseizure medications: These medications can prevent seizures that moyamoya disease causes.
• Anticoagulants: Anticoagulants can thin your blood to prevent blood clots. But these drugs have risks, like possible bleeding that’s difficult to stop. Your provider will only prescribe them in certain cases.
• Calcium channel blockers: Calcium channel blockers can lessen headaches from moyamoya disease. But these drugs can also lower blood pressure, potentially increasing stroke risk. Providers only use them in certain cases.

Medications can’t stop blood vessels from narrowing, so moyamoya disease may continue to worsen. Your healthcare provider may then consider moyamoya disease surgery. This is a type of bypass surgery that:

• Bypasses blocked arteries by using normal scalp arteries as donor arteries.
• Diverts blood flow (changes its direction) to the affected areas.
• Opens narrow blood vessels.

Your healthcare provider can discuss which method of moyamoya disease surgery would work best in your situation. They can also go over the side effects and possible complications of surgery.

Can moyamoya disease be prevented?

There’s no proven way to prevent genetic forms of moyamoya disease. But you can lower your risk of developing moyamoya syndrome by managing 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 to take your medications exactly as directed.

What can I expect if I have this condition?

For most people with moyamoya disease, the condition gets worse over time. They may also experience stroke as blood vessels narrow more and more. Without treatment, moyamoya disease can lead to stroke with severe neurological deficits. But some people remain stable for years without symptoms. Once symptoms start to develop, your provider may suggest bypass surgery.

What is the life expectancy of someone with moyamoya?

With early diagnosis and prompt treatment, people with moyamoya disease can have a normal life expectancy. Without treatment, moyamoya disease can be fatal.

When should I get emergency medical help if I have moyamoya disease?

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:

• Face droop: Does one side of your face feel numb? If you try to smile, does one side of your face droop?
• Arm weakness: Can you raise both arms? Does one arm drift lower?
• Speech: Is your speech slurred or slow? Can you repeat a simple phrase?
• Time: For any signs of stroke, call 911 or get emergency medical help immediately. Time is critical.

Other symptoms of stroke include sudden:

• Confusion.
• Numbness on one side of your body.
• Trouble seeing.
• Trouble walking.
• Severe headache.