Moyamoya disease

Moyamoya is a rare vascular disease that affects the blood vessels in the brain. Over time, the main arteries that supply blood to the brain become narrowed or blocked. These include the carotid arteries, which run along both sides of the neck and carry oxygen-rich blood from the heart to the brain.

As these arteries narrow, less blood reaches the brain. To compensate, the body forms a network of small, fragile blood vessels inside the brain. These vessels appear thin and tangled on imaging studies. The name moyamoya comes from a Japanese word meaning “puff of smoke,” which describes how this network looks. Symptoms can range from mild to severe and may appear in childhood or adulthood, most often between ages five and nine or in the 30s or 40s. Moyamoya is more common in people of Asian ancestry.

Although moyamoya is rare, it’s not uncommon at Penn Medicine. Our cerebrovascular disease care specialists have deep experience diagnosing and treating this condition. Care is highly collaborative, bringing together experts in vascular neurology, neurosurgery, neuroradiology, and stroke care across the Penn Medicine system. For children with moyamoya, Penn Medicine works closely with Children’s Hospital of Philadelphia Neuroscience Center to provide coordinated, age-appropriate care. This level of expertise means your care team understands the condition well and can plan for both current needs and long-term management.

Moyamoya symptoms often begin in childhood or middle age. In children, the condition tends to progress more quickly. Without treatment, symptoms usually worsen over time.

Symptoms may include:

• Bleeding in the brain
• Headaches that feel like migraines
• Involuntary, jerky movements
• Problems with learning or development
• Seizures
• Stroke

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