Carotid artery – moyamoyaMoyamoya (pronounced MOY-a-MOY-a) is a problem with blood flow to the brain. It happens when the major blood vessels to the brain (internal carotid arteries) become narrower (stenosis). This makes it harder for oxygen-rich blood to get through. Small blood vessels form to create a new path for blood to flow.

On a picture of the blood vessels in the brain (cerebral angiogram), the new vessels look like a puff of smoke. “Moyamoya” means “hazy puff of smoke” in Japanese. The condition was first reported in Japan.

Moyamoya slows blood flow to the brain and increases the chance of:

  • Transient ischemic attack (TIA)
  • Stroke
  • Seizures

Because of the risk of stroke, moyamoya needs urgent treatment. A stroke or TIA can cause lasting brain damage or death.

If you think your child is having a stroke, call 911.

  • When does moyamoya happen?

    Some people have moyamoya from very early childhood. Others develop it as they get older. Moyamoya does not get better on its own. It tends to get worse over time. It usually affects both sides of the brain. If a child only has moyamoya on 1 side of their brain, it may later develop on the other side.

  • What causes moyamoya?

    Doctors are not sure what causes this condition. Certain medical conditions or procedures increase the chance of having moyamoya. Risk factors include:

    • Neurofibromatoses (NF) type 1
    • Down syndrome, also called trisomy 21
    • Sickle cell disease
    • Noonan syndrome
    • Other syndromes caused by problems with chromosomes
    • Radiation therapy for a brain tumor
  • Does moyamoya run in families?

    Usually, moyamoya affects only 1 person in a family. But in some families, more than 1 person has it. If a child with moyamoya is an identical twin, the other twin should get checked for it. If other family members develop symptoms, they should get checked right away.

  • Other names for moyamoya

    This condition is sometimes called:

    • Moyamoya syndrome, when a child has moyamoya along with a linked condition, like neurofibromatosis (NF) type 1 or Down syndrome
    • Moyamoya disease, if a child does not have a linked condition but has moyamoya on both sides of their brain

Moyamoya at Seattle Children’s

Because moyamoya is very rare, most doctors never see a child with this condition. Each year Seattle Children’s treats many patients with moyamoya, from babies to young adults. We provide all aspects of care – from diagnosis to surgery to long-term follow-up. We also provide second opinions.

If you would like an appointment, ask your child’s primary care provider for a referral. If you have a referral, call 206-987-2016 to make an appointment.

If you have questions, please contact our Neurosciences Center at 206-987-2016.

  • The experts you need are here
    • Seattle Children’s is the only hospital in the Pacific Northwest with a well-developed program to treat children who have problems with blood flow in the brain. Experts at our Pediatric Vascular Neurology Program will care for your child.
    • Dr. Catherine Amlie-Lefond is a national leader in treating children who have strokes and other problems with blood vessels in their brains. She is a pediatric vascular neurologist and directs our Pediatric Vascular Neurology Program.
    • Children come here from across the country for surgery called pial synangiosis (PEE-ul sin-an-JOE-sis) to improve blood flow to their brain. Dr. Richard G. Ellenbogen performs many of these operations every year on babies, children and teens. He also has taught the operation to many other neurosurgeons.
    • Our neurosurgeons have some of the best outcomes in the nation for surgery to improve blood flow to the brain (revascularization surgery). We have the skill and special equipment needed to operate on babies, children and young adults.
  • Multidisciplinary team for comprehensive care

    Each child’s case is unique. Based on your child’s needs, your team may include specialists in: 

    If moyamoya causes reduced blood flow or a stroke, we provide rehabilitation so your child has the best possible recovery. If your child has another condition that is linked with moyamoya, team members work together and with you to develop the best treatment plan to take care of all your child’s health needs.

  • Care from birth through young adulthood

    At Seattle Children’s, we diagnose and treat moyamoya patients from birth through young adulthood. We see babies, children and teens who: 

    • Have symptoms but have not been diagnosed
    • Have been diagnosed and need surgery
    • Had surgery somewhere else for moyamoya and want to change doctors or need a second opinion about the best treatment

    We take care of your child over the long term – not only in the weeks and months before and after surgery, but for years to come. During follow-up care, we keep a watch on your child’s health to help them have the best quality of life.

    As your child gets older, we prepare them to take on a greater role in their own care. When they become adults, we help them transition to care at Harborview Medical Center.

  • Specialists in caring for kids and teens
    • Children don’t react to illness, injury, pain and medicine in the same way as adults. They need – and deserve – care designed just for them. They need a healthcare team specially trained to understand and meet their needs.
    • Our doctors have special training to diagnose and treat children. They are focused on how today’s treatment will affect your child as they develop and become adults.
    • Our experts base their treatment plans on years of experience and the newest research on what is best for children and teens.
    • As your child grows, we meet their changing needs, whether they are a youngster going back to school after brain surgery or a teen taking more responsibility for their health.
  • Support for your whole family
    • During visits, we take time to explain your child’s condition. We help you fully understand your treatment options and make the choices that are right for your family.
    • Our doctors, nurses, child life specialists and social workers help your child and your family through the challenges of their condition. We connect you to community resources and support groups.
    • At Seattle Children’s, we work with many children and families from around the Northwest and beyond. We can help with financial counseling, schooling, housing, transportation, interpreter services and spiritual care. Read about our services for patients and families.

Symptoms of Moyamoya

Moyamoya may cause headaches. But often, children have no symptoms until they have a transient ischemic attack (TIA) or stroke.

Symptoms of a TIA or a stroke from blocked blood flow (ischemic stroke) include:

  • Trouble speaking, such as slurring words
  • Weakness or numbness on one side of the body
  • Sudden vision problems, such as blurred vision
  • Trouble walking or balancing
  • Seizures

Rarely, children with moyamoya have a stroke from a burst blood vessel (hemorrhagic stroke). This type of stroke may cause:

  • Sudden, severe headache
  • Trouble walking or balancing
  • Trouble staying awake or alert
  • Nausea or vomiting

Sometimes, breathing too fast or too deeply (hyperventilating) triggers a TIA or stroke in a child with moyamoya. Crying hard or running may cause quick breathing.

Diagnosing Moyamoya

Sometimes moyamoya is found when a child has a brain scan for another reason. More often, a child has symptoms of stroke or TIA and sees a doctor who specializes in blood flow to the brain. If your child might have moyamoya, usually the doctor does a complete neurological evaluation to check:

  • Balance
  • Reflexes
  • Motor skills
  • Sense of touch
  • Memory and thinking
  • Imaging studies of the brain

    Your doctor may want pictures of your child’s brain to look at the arteries that carry blood to the brain. Your child may have 1 or more of these imaging studies:

    • MRI (magnetic resonance imaging) scan
    • MRA (magnetic resonance angiography)
    • CT (computed tomography) scan
    • Cerebral angiogram

    Sometimes, other types of imaging are needed to find out how well and how much blood flows to different parts of the brain. Your child’s team will explain which tests your child needs, why and what to expect.

Treating Moyamoya

Doctors treat moyamoya with surgery to bring new blood supply to the brain. Your child’s team at Seattle Children’s will also recommend steps to help reduce stroke risk.

  • Surgery options for moyamoya

    There are 2 main surgeries to improve blood flow in children with moyamoya: 

    • Indirect revascularization – Surgery that prompts new blood vessels to grow into the brain over time
    • Direct revascularization – Surgery that sends more blood into blood vessels already in the brain

    Both methods use your child’s superficial temporal artery (STA). Normally, this artery comes up from the neck and goes under the scalp on the side of the head. 

    • Indirect method: The neurosurgeon frees part of the STA from the scalp, places it inside the skull and attaches it to the surface the brain. Over time, new blood vessels grow and branch off the STA, bringing more blood down into the brain. This surgery is called pial synangiosis (pronounced PEE-ul sin-an-JOE-sis) or encephaloduroarteriosynangiosis.
    • Direct method: The neurosurgeon connects the STA to another artery that is already inside the skull and already brings blood to the brain (middle cerebral artery). This surgery creates a new pathway. Blood that normally goes to the scalp goes to the brain instead. This surgery is called superficial temporal artery–middle cerebral artery anastomosis, or STA-MCA anastomosis.

    We tailor treatment to your child. The neurosurgeon considers your child’s anatomy and health, and then recommends the surgery that is best for your child. Whenever possible, we use the indirect method because:

    • We believe it is safer for children
    • It doesn’t depend on good blood flow through the middle cerebral artery

    Children who often have TIAs or who have a stroke before surgery are at greater risk of having a stroke during surgery or in the next 2 weeks. Overall, this risk is low – only 4% for patients at Seattle Children’s who have pial synangiosis. To help reduce the risk, we usually wait 4 to 6 weeks after a stroke to do surgery.

  • Care after surgery

    Most children do very well after surgery. Your child will have pain medicine to keep them comfortable. We will watch your child in the intensive care unit for 1 to 2 days until we are sure they are doing well. Then your child will stay in a regular hospital room 2 to 3 days. Most children can go home 4 to 5 days after surgery.

    Before your child goes home, your child’s team will explain any special care or precautions needed after surgery. Here are some typical things you can expect for your child:

    • Return to regular activities at home and school within 2 to 4 weeks after surgery.
    • Avoid strenuous activities for 3 months and then slowly increase their activity over the next few months.
    • Wear a helmet during activities like biking, skateboarding or inline skating.
    • Avoid activities that involve head contact until your child’s doctor says it’s OK.

    After pial synangiosis, new arteries start growing into the brain. This continues for at least a year. During this time, your child may have headaches or TIAs. Over time, this should improve. We ask you to keep track of your child’s symptoms so we can talk about them at follow-up visits and give your child any tests or treatments they need.

    We tailor the follow-up schedule to your child’s needs. Here is what usually happens:

    • About 2 weeks after surgery, the neurosurgery team will see your child for a follow-up visit. We check your child’s healing and remove their stitches.
    • In about 3 months, a neurosurgeon and a neurologist will see your child for a follow-up visit. Your child will have an MRI (magnetic resonance imaging) scan and a cerebral angiogram. These tests check blood flow in the affected areas of your child’s brain.
    • Each year, your child will have a brain scan.
  • Lowering the risk of stroke

    Even after surgery, your child will have a higher risk of stroke than most children. Some blood vessels in your child’s brain will not be as big as normal. Some children who have moyamoya on only 1 side of their brain may develop it later on the other side.

    We will teach you – and your child, when they are old enough – how to lessen the risk of stroke. Steps include the following:

    • Taking a low dose of aspirin each day to prevent blood clots that could block small arteries.
    • Drinking water and other fluids each day to keep your child’s blood volume and blood pressure high enough for good blood flow.
    • Avoiding medicines that constrict the blood vessels, unless recommended by a doctor who knows about moyamoya and your child’s health history. These include medicines for migraine headaches.
    • Using with caution medicines that increase the risk of blood clots, such as birth control pills.
    • Protecting the brain and its arteries with a helmet during activities like biking.
    • Avoiding strenuous activity in the months right after surgery. Talk to your child’s team about the right level of activity for your child.
  • Ongoing care

    Seattle Children’s provides long-term follow-up care to: 

    • Monitor your child’s health
    • Prevent complications
    • Manage symptoms or other health problems
    • Improve your child’s quality of life Ongoing care will depend on your child’s needs.

    For example, if reduced blood flow damaged your child’s brain, they may benefit from:

    Our team is experienced in helping children return to school and other important activities after brain surgery or treatment for stroke. We also work with you to find resources in your community.

  • Transition to adult care

    As your child gets older, we prepare them to take on a greater role in their own care. When your child is ready to transition to adult care, we connect them with experts who can meet their adult healthcare needs.

    We work closely with the neurosurgeons at Harborview Medical Center who treat moyamoya. Many of the doctors who treat moyamoya at Seattle Children’s also treat adults with moyamoya at Harborview.

Contact Us

If you would like an appointment, ask your child’s primary care provider for a referral. If you have a referral, call 206-987-2016 to make an appointment.

Providers, see how to refer a patient.

If you have questions, contact us at 206-987-2016 or 844-935-3467 (toll free).