Moyamoya disease

Moyamoya is a rare vascular disease of the brain in which the main arteries that supply blood to your brain become narrowed and blocked. In moyamoya disease, the carotid arteries narrow over time. You have two carotid arteries on either side of your neck that carry oxygen-rich blood from your heart to your brain.

As the arteries become narrow, blood flow decreases. A network of small, fragile blood vessels forms within your brain to offset this decrease. Moyamoya is a Japanese word for "puff of smoke," which describes the appearance of the thin, tangled vessels.

Though moyamoya is an uncommon disease, it is not rare at Penn Medicine. Our doctors frequently treat patients with moyamoya disease. They have a depth of knowledge and experience you won’t find elsewhere in the region.

Who is affected by moyamoya?

People with moyamoya disease usually develop symptoms between the ages of five and nine or in their 30s or 40s. Moyamoya is more common in people of Asian ancestry.

Moyamoya is a rare brain condition, with symptoms ranging from mild to severe in both children and adults. Without treatment, moyamoya continues to progress and affect blood flow to the brain. Find out more about moyamoya disease care for children at the Children’s Hospital of Philadelphia Neuroscience Center.

Moyamoya symptoms typically show up in childhood or middle age and include stroke, headaches and seizures. The condition, and its symptoms, progresses more rapidly in children than adults.

Symptoms of moyamoya disease include:

• Bleeding (hemorrhage) in the brain
• Involuntary, jerky movements
• Migraine-like headaches
• Problems with learning and development
• Seizures
• Stroke

Without treatment, symptoms of moyamoya usually get worse over time. Children often experience a faster disease progression.

Complications of moyamoya disease

The main risks of moyamoya disease include:

• Ischemic stroke due to reduced blood supply to the brain due to a blocked carotid artery
• Hemorrhagic stroke caused by bleeding (hemorrhage) from the thin moyamoya blood vessels

Moyamoya disease and ischemic stroke

Some people with moyamoya disease experience an ischemic stroke as their first symptom. Stroke can occur in children and adults with moyamoya disease and can be life-threatening.

In some cases, a transient ischemic attack (TIA) or "mini-stroke" is the first sign. The symptoms of a TIA appear and go away quickly. But a TIA is a warning sign of a more severe stroke.

Call 911 if you or your child experiences any stroke symptoms, even if they go away quickly:

• Numbness or weakness in the face, arm or leg on one side of the body
• Loss of balance or coordination
• Severe, sudden headache
• Trouble speaking

Moyamoya disease and hemorrhagic stroke

The thin moyamoya blood vessels can break open and bleed (hemorrhage). This blood can damage surrounding brain tissue. If the bleeding is severe, it can lead to a dangerous hemorrhagic stroke. This outcome is more common in adults than children.

Doctors do not fully understand what causes moyamoya disease. It can be an inherited condition or appear as an isolated, random disease. 

Moyamoya syndrome refers to moyamoya disease associated with other conditions that affect brain arteries, such as: 

• Down syndrome 
• Neurofibromatosis 
• Sickle cell disease 

There is no cure for moyamoya disease. Surgical treatment will help improve blood flow to the brain.

Moyamoya disease surgery and treatment at Penn

Your moyamoya disease treatment plan may include medications to reduce headaches, seizures and the formation of blood clots. But since moyamoya is a progressive disease, surgery is usually the primary treatment option.

The goal of surgery is to restore the flow of blood (revascularization) to your brain. Surgical techniques include:

• Indirect revascularization: The surgeon moves a blood vessel, usually from the scalp to the surface of the brain. This leads to the growth of new blood vessels in the brain.
• Direct revascularization: The surgeon attaches a blood vessel from the scalp directly to a branch of the cerebral artery.

Early diagnosis and treatment can greatly reduce symptoms and the risk of stroke. At Penn Medicine, our doctors develop a treatment plan to reduce this risk and safeguard your health.