iSymptom

ConditionBrain & nerves

Moyamoya Disease

Moyamoya disease is a rare, progressive condition in which the internal carotid arteries and their main branches at the base of the brain gradually narrow and close. The brain grows a network of tiny fragile collateral vessels that looks like a "puff of smoke" (moyamoya in Japanese) on scans. It causes transient ischemic attacks and strokes, especially in children, and bleeding strokes more often in adults. It is most common in East Asian populations. Revascularization surgery to bring new blood supply to the brain greatly reduces stroke risk.

Also called: Moyamoya syndrome (when linked to another condition), spontaneous occlusion of the circle of Willis, progressive intracranial arterial occlusion

By the iSymptom editorial team · Updated · 3 min read

At a glance

What it is
Progressive narrowing of the large arteries at the base of the brain, with fragile collateral vessels.
Who gets it
Peaks in children aged 5 to 10 and adults aged 30 to 50; more common in East Asian and female patients.
Symptoms
TIAs, strokes, seizures, headaches; bleeding in the brain in adults.
Diagnosis
MRI/MRA and cerebral angiography.
Treatment
Revascularization surgery, aspirin, hydration and avoiding hyperventilation.

When to get help

Call 911 or go to the ER

  • Sudden weakness or numbness of the face, arm or leg, trouble speaking, confusion, or vision loss: call 911 or your local emergency number
  • A sudden severe headache, vomiting or reduced consciousness (possible bleeding in the brain)
  • A seizure in a child or adult known to have moyamoya

See a doctor within a day or two

  • Brief episodes of weakness, numbness or speech difficulty that fully resolve (TIAs), especially in a child, often triggered by crying, blowing or hard exercise
  • Worsening headaches or new learning or behavior problems in a child with moyamoya

Book a routine appointment

  • A child with Down syndrome, sickle cell disease or neurofibromatosis type 1 with any unexplained neurological symptoms, for screening
  • Relatives of someone with familial moyamoya

Moyamoya disease vs moyamoya syndrome

  • Moyamoya disease occurs on its own without an associated condition. Variants in the RNF213 gene, common in East Asian populations, increase susceptibility.
  • Moyamoya syndrome is the same pattern occurring with another condition, such as: - sickle cell disease - Down syndrome - neurofibromatosis type 1 - previous radiation to the head or neck - thyroid disease, especially Graves' disease - some genetic syndromes

Symptoms

In children

  • transient ischemic attacks: brief episodes of weakness on one side, numbness, speech difficulty or involuntary movements, often triggered by crying, coughing, blowing (e.g. on hot food or instruments), straining or hyperventilation, which constrict brain vessels
  • ischemic strokes with lasting weakness
  • seizures
  • headaches
  • developmental delay or learning difficulties from repeated silent strokes

In adults

  • ischemic strokes and TIAs
  • bleeding in the brain (intracerebral hemorrhage) from the fragile collateral vessels, more common than in children
  • headaches and cognitive decline

Diagnosis

  • MRI and MRA (magnetic resonance angiography): show narrowing of the arteries, old strokes and collaterals
  • Catheter cerebral angiography: the gold standard, showing the "puff of smoke" collaterals and staging the disease
  • Perfusion studies (perfusion MRI, SPECT or PET) to measure brain blood flow and reserve
  • EEG for seizures
  • blood tests and screening for associated conditions

Treatment

There is no medicine that reverses the narrowing. Treatment aims to prevent strokes.

Revascularization surgery

Surgery is the main treatment for people with symptoms or reduced blood flow:

  • direct bypass: connecting a scalp artery (superficial temporal artery) to a brain artery (middle cerebral artery), providing immediate new flow; more often used in adults
  • indirect revascularization: laying a scalp artery, muscle or membrane on the brain surface so new vessels grow in over months (for example EDAS or pial synangiosis); commonly used in children
  • combined approaches

Surgery significantly reduces the risk of future stroke in most patients.

Medical management

  • aspirin to reduce clotting, especially in ischemic types
  • staying well hydrated, especially during illness, heat or before procedures
  • avoiding hyperventilation, dehydration and low blood pressure
  • careful anesthesia planning
  • treating seizures, headaches and associated conditions
  • blood transfusion programs for children with sickle cell disease

Rehabilitation

Physical, occupational and speech therapy after strokes; educational support for children.

Outlook

Moyamoya is progressive without treatment, with a high risk of recurrent strokes. After revascularization surgery, most children and adults have far fewer strokes and good long-term outcomes. Outcomes depend largely on how much brain injury occurred before treatment, so early diagnosis matters.

Frequently asked questions

What are the symptoms of moyamoya disease?

Symptoms include repeated mini-strokes (TIAs) with temporary weakness, numbness or speech problems, strokes, seizures and headaches. In children, episodes are often triggered by crying or exertion. Adults are more likely to have bleeding in the brain.

What causes moyamoya disease?

The exact cause is unknown. Genetic factors, especially variants in the RNF213 gene, increase susceptibility, mainly in East Asian populations. Moyamoya syndrome occurs alongside conditions such as sickle cell disease, Down syndrome, neurofibromatosis type 1 and previous head radiation.

Can moyamoya disease be cured?

The arterial narrowing cannot be reversed, but revascularization surgery creates new blood supply to the brain and greatly lowers the risk of stroke. Many people lead active lives after surgery.

What is the life expectancy with moyamoya disease?

With timely surgery, many people have a normal or near-normal life expectancy. Outcomes are worse when large strokes or brain bleeds have already occurred, which is why early diagnosis and treatment are important.

Sources

This guide was written from current patient and clinical guidance, including:

  • American Heart Association/American Stroke Association: Scientific statement on moyamoya disease
  • National Institute of Neurological Disorders and Stroke: Moyamoya disease
  • MedlinePlus Genetics: Moyamoya disease
  • American Association of Neurological Surgeons: Moyamoya disease
  • Boston Children's Hospital: Moyamoya