Moyamoya is a very rare cerebrovascular condition that affects the arteries that carry blood to the brain. The condition causes the blood vessels to become narrow, which slows down blood flow. When this happens, the body makes new blood vessels at the base of the brain (moyamoya collateral vessels) in an attempt to increase blood flow. These new arteries pass through the basal ganglia and the thalamus and are more fragile than normal arteries.
Moyamoya gets its name from the Japanese word for “puff of smoke.” When viewed on a cerebral angiogram, the new blood vessels look like black wispy clouds or a puff of smoke drifting into the air.
In most cases, there is no known cause for moyamoya, but it can be found in association with other conditions such as:
- Brain tumors at the base of the brain that form after radiation therapy
- Down syndrome
- Connective tissue disorders (Ehlers-Danlos syndrome, Marfan syndrome)
- Graves' disease
- Sickle cell disease
Some children may develop moyamoya after radiation therapy or after a viral illness. About 1 in 10 children with moyamoya also have a relative with the condition. In those cases, the condition may be inherited.
Moyamoya can occur in both children and adults.
The symptoms of moyamoya are caused by reduced blood flow to the brain and weakened blood vessels. The first sign of moyamoya is often a transient ischemic attack or a stroke. Symptoms of moyamoya include:
- Stroke or stroke-like symptoms
- Transient ischemic attacks (ministrokes)
- Weakness or numbness on one side of the body
- Tingling on one side of the body
- Migraine-like headaches
Moyamoya can affect one (unilateral) or both sides (bilateral) of the brain. Without treatment, children with moyamoya can experience multiple strokes that can lead to progressive intellectual and cognitive disability.
If your child shows signs of moyamoya, neurologists and neurosurgeons will perform specific tests to make an accurate diagnosis. Surgery is the only cure for moyamoya. Most children make a complete recovery and can return to normal activities within a month.
Diagnosis of Moyamoya
The following exams and tests are performed to diagnose moyamoya:
- Medical history. A neurologist or neurosurgeon will review your child’s medical history.
- Neurological exam. The doctor will perform a detailed neurological exam, looking for signs of moyamoya, including weakness and/or numbness or tingling in the limbs.
- Cerebral angiogram. A neurointerventionalist uses this test to study the arteries in the brain. A cerebral angiogram is performed while your child is asleep under anesthesia. Moyamoya precautions are used during anesthesia to ensure your child’s safety and to avoid the risk of stroke. A catheter is inserted into the femoral artery in the leg. The catheter is passed from the femoral artery to the internal carotid artery in the neck. Dye is then injected into the catheter and flows through selected arteries of the brain and the external carotid circulation. A cerebral angiogram highlights blockages and the formation of any new blood vessels. It creates a map of the brain’s blood vessels. This map is used to determine the need for surgery and the availability of external carotid vessels that can be used as donor vessels for surgery.
If diagnostic tests determine that moyamoya disease is present, a neurosurgeon will discuss the condition with you and your child and will work with you to create a surgery plan for definitive treatment.
The goal of treatment for moyamoya is to restore blood flow to the brain and remove the risk of stroke. Treatment for moyamoya includes:
- Pial synangiosis surgery. Surgery is the only treatment for moyamoya. A pediatric neurosurgeon performs this type of revascularization surgery by transferring a healthy branch of the external carotid artery supplying the scalp to the pial surface of the brain. The healthy artery is secured to the pial surface of the brain after opening the dura and arachnoid, and new collateral blood vessels grow in and restore blood flow to the brain. This is a delicate procedure performed with the use of a high-powered operating microscope. If moyamoya is present on both sides of the brain, two separate surgeries on different days will be performed for the best and safest results. Children typically spend two to three days in the hospital after surgery. They can return to school within two weeks and can take part in normal activities about four weeks after surgery.
- Moyamoya anesthesia protocol. Children with moyamoya are at increased risk of stroke, especially when under anesthesia. The anesthesiologists at Riley at IU Health carefully monitor patients during surgery to maintain the proper blood pressure and hydration and prevent hyperventilation to avoid a stroke. Intraoperative electroencephalogram monitoring is also used to track any potential seizure activity during surgery.
- Aspirin. Children with moyamoya take a daily dose of aspirin for the rest of their lives as a method of stroke prevention.
Despite moyamoya being a rare condition, pediatric neurosurgeons at Riley at IU Health perform more than 20 pial synangiosis surgeries a year. We are one of only a few hospitals in the U.S. trained in the pial synangiosis surgery technique. As a result, we provide a robust moyamoya treatment program.
Key Points to Remember
Key Points to Remember
- Moyamoya is a cerebrovascular condition that causes arteries at the base of the brain to narrow or become blocked. This restricts blood flow to the brain.
- The first sign of moyamoya is often a transient ischemic attack or stroke. Other common signs of moyamoya include seizures and migraine-like headaches.
- Moyamoya can also be associated with other conditions such as Down syndrome, neurofibromatosis and sickle cell disease as well as brain tumors at the base of the brain that form after radiation therapy.
- The only treatment for moyamoya is revascularization surgery, which helps restore blood flow to the brain.
Support Services & Resources
Support Services & Resources
Visit the links below to discover support groups and more resources for moyamoya disease.
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
This government website provides an overview of moyamoya, plus information about treatment, prognosis, research and clinical trials.
This article is about understanding and treating moyamoya disease in children.
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