Moyamoya disease is a condition that affects blood flow to the brain, often causing strokes and bleeding in the brain.

Moyamoya disease is a rare condition that affects blood flow to the brain. The carotid artery becomes blocked or narrowed, and small blood vessels develop at the base of the brain to supply the brain with blood.

People with moyamoya disease may experience complications like stroke or bleeding in the brain. It can also affect the way their brain develops, leading to cognitive delays or intellectual disabilities.

Moyamoya disease can be treated through medication and surgery. With the right treatment, it’s possible for people with moyamoya disease to live long, healthy lives.

Moyamoya disease is a cerebrovascular condition, meaning that it affects blood flow to the brain. This condition mostly affects children, but it can also affect adults.

Your brain needs a constant supply of oxygen and nutrients in order to function. Blood, which travels to the brain through blood vessels, supplies the brain with oxygen and nutrients. When blood flow to the brain is compromised, a number of complications can occur.

In moyamoya disease, the carotid artery in the skull becomes blocked or narrowed, reducing blood flow to the brain. To compensate for this blockage, small blood vessels develop at the brain’s base to supply it with blood.

Moyamoya was first identified in Japan. Moyamoya means “puff of smoke” in Japanese, a reference to the appearance of the tiny vessels at the base of the brain.

How rare is moyamoya disease?

A recent review of studies found that 10.5 people in every 100,000 in Japan experience moyamoya disease at some point in their lives. In South Korea, 16.1 people in every 100,000 experience moyamoya disease.

The Genetic and Rare Diseases Information Center estimates that fewer than 5,000 people in the United States have moyamoya disease.

People of all ages may have moyamoya disease, but it’s more common in children. The symptoms in children can differ from those in adults.

In children, the symptoms usually occur between 5 and 10 years of age. The first symptom is usually a stroke or ministroke (also called a transient ischemic attack, or TIA).

Adults with moyamoya disease typically experience symptoms between 30 and 50 years of age. Adults may also experience strokes or TIAs, but more commonly, they experience bleeding in the brain, also called a hemorrhagic stroke.

The symptoms of moyamoya disease that occur at any age can include:

  • aphasia (difficulties with speaking or understanding others)
  • cognitive or developmental delays
  • frequent headaches
  • involuntary movements
  • paralysis or weakness in your face, arm, or leg, usually on one side of the body
  • seizures
  • vision problems

If you think you are or have experienced a stroke, it’s important to seek immediate medical attention.

Moyamoya disease is a progressive disease, meaning that it can gradually get worse without treatment.

The “Suzuki stages” are used to describe the different stages of moyamoya disease. An angiogram, a type of X-ray used to examine blood vessels, is typically used to identify which stage someone is in.

Stage 1: Narrowing of carotid fork

At this stage, only one part of the internal carotid artery is narrowed or blocked.

Stage 2: Initiation and appearance of basal moyamoya

All the terminal branches of the internal carotid artery are narrowed. Deep moyamoya vessels — that is, the tiny blood vessels that develop at the base of the brain — are visible on an angiogram.

Stage 3: Intensification of basal moyamoya

More deep moyamoya vessels can be seen. Blood flow through the anterior cerebral artery and middle cerebral arteries is compromised.

Stage 4: Minimization of basal moyamoya

The deep moyamoya vessels begin to regress. Other vessels, called transdural collateral vessels, begin to appear. Blood flow through the posterior cerebral artery is compromised.

Stage 5: Reduction of moyamoya

The deep moyamoya vessels continue to regress, while more transdural collateral vessels appear.

Stage 6: Disappearance of moyamoya

The deep moyamoya vessels have vanished, and the internal carotid artery is completely narrowed or blocked. The blood supply to the anterior cerebral artery and middle cerebral arteries comes mostly from the external carotid artery.

The causes of moyamoya disease are unclear. Based on the available research, it seems that genetics may play a role in whether someone develops moyamoya disease.

Researchers have identified certain risk factors for moyamoya disease, including:

  • Gender: Moyamoya disease is slightly more common among women and girls.
  • Ethnicity: Moyamoya disease is more common among people who have East Asian heritage, especially those who have Korean and Japanese heritage.
  • Family history: You’re 30 to 40 times more likely to have moyamoya disease if a close blood relative has the condition.

These factors suggest that there’s a strong genetic component to moyamoya disease.

Moyamoya disease is usually diagnosed by a neurologist. Certain neurologists specialize in moyamoya disease and related conditions.

Usually, a clinician will review your symptoms and your family’s medical history. They may need to conduct a physical examination to rule out other conditions and to diagnose moyamoya.

In order to diagnose moyamoya disease, doctors may use tools that allow them to view the blood vessels in the brain and measure the blood supply to the brain.

The following tools can be used to test for moyamoya disease:

The doctor may also order other tests to rule out other possible causes of your symptoms.

If treated, people with moyamoya disease can have an average life expectancy.

Although moyamoya can be fatal, surgery and medication can prevent moyamoya disease from getting worse. In some cases, surgery can greatly reduce strokes and brain hemorrhaging or stop them altogether.

Is moyamoya disease terminal?

There’s no cure for moyamoya disease, and it’s a lifelong condition. However, when treated correctly, moyamoya disease can be managed. Many people experience fewer or no strokes after surgery, and medication can manage the symptoms of moyamoya disease.

Without treatment, the brain’s blood supply may decrease over time. As a result, people with moyamoya disease may experience multiple strokes and mental decline. When moyamoya disease is left untreated, it can be fatal. Because of this, it’s important that moyamoya disease is treated as soon as possible.

Moyamoya disease can be treated through surgery or medications. Some people with moyamoya disease experience no further strokes or complications after surgery.

Surgery is the primary treatment for moyamoya disease. Certain surgeries, called revascularizations, can open narrowed blood vessels or bypass blocked vessels and improve blood flow to the brain.

Certain medications can also help people with moyamoya disease. For example:

Because moyamoya disease affects brain functioning, occupational or physical therapy may help improve one’s quality of life. For example, it can help you build developmental skills and improve physical function affected by a stroke.

Moyamoya disease is a rare condition that affects the brain’s blood supply. Although it’s a serious and potentially fatal condition, the correct treatment can help improve the symptoms significantly. When treated, a person with moyamoya disease can live a full and healthy life.