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Moyamoya syndrome is a rare and complex condition that affects children, targeting the brain’s arteries and reducing blood flow to the brain. Although it is uncommon, early diagnosis and proper treatment can protect the child from serious complications such as strokes or impaired cognitive and motor abilities. In this Dalili Medical article, we will explore the causes of Moyamoya syndrome in children, its main symptoms, and the available treatments with medication and surgery. We will also provide practical care tips after surgery, making this a complete guide to understanding the condition and managing it in a safe and scientific way.

What is Moyamoya Disease in Children?

Moyamoya disease is a rare but serious condition that affects one or both internal carotid arteries at the base of the brain. Over time, these arteries become narrowed, reducing blood flow to the brain. This can lead to blood clots, strokes, or transient ischemic attacks (mini-strokes).

In some cases, the brain tries to compensate by forming a network of tiny blood vessels to deliver blood to affected areas. On imaging scans, these vessels appear like a “puff of smoke,” which is the meaning of the Japanese word Moyamoya.

How Common is Moyamoya Disease?

In the United States, it affects about 1 child per million people.
Most cases are diagnosed in childhood, with the average age around 7 years.
It can also occur in adults, but is more common in children.
Girls are almost twice as likely to develop the condition compared to boys.
It is more common among people of Asian descent, especially in Japan.

Causes of Moyamoya Disease

The exact cause is still unclear, but possible factors include:

Genetic factors: Mutations in blood vessel-related genes, such as RNF213.
Associated conditions: Down syndrome, sickle cell anemia, autoimmune disorders, and certain thyroid diseases.
Radiation exposure: Previous head or brain radiation treatment.
Unknown causes: In some children, the disease develops without an identifiable trigger (Primary Moyamoya).

Why is it Called Moyamoya?

The name comes from the Japanese term meaning “puff of smoke.” Doctors first observed that the small collateral vessels formed by the brain appear smoky and hazy on angiography.

Stages of Moyamoya Disease (Suzuki Classification)

Moyamoya progresses in six stages as arteries narrow and collateral vessels develop:

Early narrowing of the internal carotid artery.
Small collateral vessels start to form (“smoke” appears).
Major artery narrowing with larger Moyamoya vessels.
Severe blockage, collateral vessels weaken, external arteries support blood flow.
Moyamoya vessels gradually disappear, brain depends more on external arteries.
Almost complete blockage of main arteries, collateral vessels vanish — the most dangerous stage.

Symptoms and Warning Signs in Children

The first sign is often an ischemic stroke caused by reduced blood supply to brain tissue. If blood flow stops for more than 3 minutes, brain cells begin to die.

Common symptoms include:

Weakness or numbness on one side of the body.
Vision loss or double vision.
Trouble speaking or understanding speech.
Difficulty walking or standing.
Severe headaches, sometimes with vomiting or drowsiness.
Seizures.

Sometimes symptoms disappear quickly (called Transient Ischemic Attacks – TIA), but these are warning signs of a possible stroke.

⚠️ Important: If you notice these symptoms in your child, seek immediate medical help. Early treatment greatly reduces the risk of permanent brain damage.

Complications of Moyamoya Disease in Children

If untreated, Moyamoya can cause:

Strokes leading to permanent weakness or paralysis.
TIA (mini-strokes) causing temporary symptoms.
Brain hemorrhage due to fragile blood vessels.
Seizures.
Cognitive and behavioral difficulties such as poor concentration, learning delays, or social withdrawal.
Developmental delays in speech or motor skills.
Permanent disabilities in advanced cases with repeated strokes.

Diagnosing Moyamoya Disease in Children

Because symptoms can mimic other neurological disorders, diagnosis requires detailed evaluation:

Medical history and neurological exam – checking for weakness, speech, vision, or memory issues.
Imaging tests:
- MRI – detects brain damage from reduced blood flow.
- MRA (Magnetic Resonance Angiography) – shows narrowing or blockage in arteries.
- CT scan – helps detect old strokes or brain hemorrhage.
Genetic testing (sometimes) – to identify related mutations.

Diagnostic Tests for Moyamoya Disease in Children

3. Cerebral Angiography

The most accurate diagnostic method.
Shows the exact narrowing of arteries and the characteristic “smoky” Moyamoya vessels.
Helps determine the disease stage (Suzuki classification, stages I–VI).

4. Additional Tests

EEG (Electroencephalogram): if the child has seizures.
Blood tests: to rule out associated conditions such as sickle cell anemia or thyroid problems.
Genetic testing: sometimes performed when there is a family history.

⚠️ Note: Very early diagnosis significantly reduces the risk of strokes and long-term disability, especially if surgery is performed at early stages.

How is Moyamoya Disease Treated in Children?

The main treatment is surgery, aiming to:

Restore blood flow to narrowed brain arteries.
Prevent strokes and permanent damage.

Although surgery is the most effective long-term solution, doctors may also prescribe medications to control symptoms, such as:

Aspirin: to prevent blood clots.
Calcium channel blockers (e.g., Verapamil): to lower blood pressure and improve blood flow.

Types of Surgery for Moyamoya

There are several surgical approaches to create new blood supply routes to the brain:

Scalp vessel connection
– Healthy blood vessels from the scalp are redirected to the brain to bypass narrowed arteries.
EDAS (Encephaloduroarteriosynangiosis)
– The superficial temporal artery is placed on the brain surface through a small opening in the skull.
– Over time, new vessels grow into the brain tissue.
EMS (Encephalomyosynangiosis)
– Part of the temporal muscle is attached to the brain surface.
– This muscle gradually produces new blood vessels.
Omental Transplant
– The omentum (a fatty tissue rich in blood vessels from the abdomen) is placed on the brain surface.
– Provides gradual new blood supply.
Dural Flip
– Blood-rich dura mater (outer brain covering) is flipped and laid onto the brain surface.
Direct Arterial Bypass
– A scalp artery (e.g., superficial temporal artery) is directly connected to a brain artery.
– Provides immediate improvement in blood flow.

When to Seek Emergency Medical Help

Parents should call the doctor or go to the emergency room immediately if the child develops:

Sudden seizures or convulsions.
Weakness or numbness in the face, arm, or leg (especially one side).
Difficulty speaking or understanding speech.
Vision problems, such as double vision or temporary blindness.
Sudden, severe headache.
Dizziness, loss of balance, or fainting.
Any sudden change in behavior, concentration, or memory.

Medications for Moyamoya Disease in Children

Medications alone cannot cure Moyamoya, but they help manage symptoms and reduce complications, especially before surgery.

Common drugs include:

Antiplatelet therapy (e.g., low-dose aspirin): prevents clot formation in narrowed arteries.
Anticoagulants (e.g., heparin, warfarin): rarely used in children, only if clot risk is very high.
Anti-seizure medications: for children with seizures.
Blood pressure or thyroid medications: if the disease is linked to hypertension or thyroid disorders.
Pain relievers: for recurrent headaches.

⚠️ Important: Surgery remains the only definitive treatment to prevent long-term complications.

Surgical Goals for Moyamoya

Deliver blood to the brain by connecting external arteries to narrowed internal ones.
Prevent strokes and ischemic attacks.
Improve brain perfusion and reduce the risk of bleeding or permanent disability.

Surgical Approaches:

Direct revascularization (STA-MCA bypass): immediate blood supply, usually for older children with larger arteries.
Indirect revascularization (EDAS, EMS, omental transplant): suitable for younger children, as vessels grow gradually.
Combined procedures: use both direct and indirect methods for maximum benefit.

Post-Surgical Care for Children with Moyamoya

Hospital Stay

Typically 3–7 days, depending on the procedure.
Neurological monitoring (speech, movement, concentration).
Vital signs: blood pressure, heart rate, temperature.
Pain control with child-safe medications.

Medications After Surgery

Aspirin or antiplatelet drugs to prevent new clots.
Pain relievers as needed.
Anti-seizure drugs if seizures were present before surgery.

Diet and Physical Activity

Gradual reintroduction of food.
Limited physical activity for a few weeks.
Gradual return to normal activities after medical approval.

Follow-Up Care

MRI/MRA scans to monitor new vessel growth.
Regular checkups for associated conditions (blood pressure, thyroid, anemia).
Monitoring school performance, focus, and learning abilities.

Important Notes for Parents

Seek urgent care for severe headache, weakness, speech problems, or loss of consciousness.
Provide emotional support, as children may feel anxious after surgery.
Educational support may be needed for children with concentration or learning difficulties.