Moyamoya Disease: Symptoms, Causes, and Treatment Options

A rare progressive brain disease that narrows the main arteries supplying blood to the brain. NJBS neurovascular specialists offer the latest surgical and medical treatments for moyamoya disease.

By Dr. Karimi

What Is Moyamoya Disease?

Moyamoya disease is a rare, progressive brain condition that narrows the internal carotid arteries at the base of the brain. As the main arteries become progressively blocked, the brain attempts to compensate by developing fragile collateral blood vessels. These abnormal vessels create the characteristic appearance on angiography that gives the disease its Japanese name: moyamoya, which means ‘puff of smoke.’ This ‘puff of smoke’ appearance reflects the hazy tangle of abnormal small vessels that form in response to arterial narrowing.

The disease occurs without an obvious external cause and is typically not linked to standard vascular risk factors such as high cholesterol or smoking, though it does have a genetic basis in some families. Over time, the progressive narrowing reduces blood flow to the brain, increasing the risk of stroke.

Who Does Moyamoya Disease Affect?

Moyamoya disease is more common in people of Asian descent, particularly those from Korea, Japan, and China, but it affects individuals of all ethnic backgrounds. According to the National Institute of Neurological Disorders and Stroke (NINDS), the disease is often diagnosed in children between 10 and 14 years of age, though it also appears in adults, with a second peak of diagnosis in the 40s. Some research indicates that women are more likely than men to develop the condition. Family history is important: if a close relative has moyamoya disease, your risk is 30 to 40 times higher than that of the general population, reflecting a genetic component in a subset of cases.

Symptoms of Moyamoya Disease

Moyamoya disease may cause no symptoms in its early stages, but as the disease progresses, the reduced blood flow to the brain often triggers neurological events. Symptoms differ between children and adults.

Common Symptoms

• Transient ischemic attacks (TIAs), also called mini-strokes: brief episodes of neurological symptoms that resolve within minutes to hours, including sudden weakness or numbness on one side of the body, slurred speech, or difficulty moving
• Stroke: sudden loss of brain function caused by interrupted blood flow, resulting in weakness, paralysis, vision loss, speech difficulty, or loss of consciousness
• Weakness or paralysis on one side of the body
• Speech difficulties or slurred speech
• Vision problems, including blurred vision or loss of vision in one eye
• Headaches, sometimes severe or change in headache pattern
• Cognitive changes: difficulty concentrating, memory problems, or confusion
• Dizziness or loss of balance

Differences Between Children and Adults

In children, the first symptom of moyamoya disease is often a transient ischemic attack (TIA), which may present as temporary weakness or numbness. Children with moyamoya disease are at higher risk for ischemic stroke (caused by blood clots or reduced blood flow). Adults with moyamoya disease are more likely to experience hemorrhagic stroke, which occurs when fragile blood vessels rupture and bleed into the brain. This difference in presentation is important for understanding treatment decisions.

When to See a Specialist

Sudden neurological symptoms such as facial drooping, arm weakness, speech slurring, or vision loss require emergency evaluation. Call 911 immediately if you or a loved one experiences these symptoms. For symptoms that develop more gradually such as progressive headaches, cognitive changes, or recurrent TIA-like episodes, prompt consultation with a neurovascular specialist is warranted. Early diagnosis can help prevent stroke and guide treatment decisions.

Causes and Risk Factors

Causes: The Underlying Arteriopathy

The precise cause of moyamoya disease remains incompletely understood. The disease involves a progressive narrowing of the internal carotid arteries and their branches at the base of the brain. This narrowing triggers abnormal formation of small collateral vessels in the basal ganglia region. The arterial narrowing is not caused by atherosclerosis, plaque buildup, or inflammation typical of other cerebrovascular diseases. Genetic mutations, particularly in the RNF213 gene, have been identified in some families and may predispose individuals to developing the disease, though genetic testing is not routinely performed and more than half of all moyamoya disease cases have no identified genetic mutation.

Risk Factors

• Asian ethnicity, especially of Korean, Japanese, or Chinese descent
• Family history: having a first-degree relative with moyamoya disease
• Female sex: women are diagnosed at higher rates than men
• Down syndrome
• Sickle cell disease
• Prior radiation therapy to the head (associated radiation-induced moyamoya)
• Neurofibromatosis type 1

The presence of a risk factor does not guarantee that someone will develop moyamoya disease, and many people with risk factors never develop the condition. Genetic counseling may be appropriate for families with multiple affected members.

How NJBS Diagnoses Moyamoya Disease

Diagnosis of moyamoya disease requires imaging studies that visualize the brain’s blood vessels. A thorough diagnostic workup typically includes multiple imaging approaches:

MRI and MRA (Magnetic Resonance Angiography)

MRI provides detailed images of the brain’s structure and can show signs of prior stroke or tissue damage. MRA uses the same magnet to visualize blood vessels without requiring injection of contrast dye. Together, these studies can reveal the characteristic narrowing of the internal carotid arteries and the abnormal collateral vessels (the ‘puff of smoke’ appearance). MRI and MRA are typically the first imaging tests ordered when moyamoya disease is suspected.

Cerebral Angiography (Gold Standard)

Catheter-based cerebral angiography remains the gold standard for diagnosing moyamoya disease. In this procedure, a thin catheter is threaded through the blood vessels from the groin or arm to the arteries in the brain. A contrast dye is injected and x-ray images are obtained, providing the clearest view of vessel narrowing and collateral vessel development. Although it is more invasive than MRI, cerebral angiography provides the most detailed anatomical information and allows the neurovascular surgeon to plan surgical revascularization if needed.

Cerebral Perfusion Imaging

Perfusion studies such as CT perfusion or advanced MRI perfusion techniques measure blood flow to different regions of the brain. These studies help assess the severity of reduced blood flow and identify brain tissue at highest risk for stroke. The information guides decisions about treatment urgency and surgical candidacy.

Treatment Options for Moyamoya Disease

Non-Surgical Management

Some patients, particularly those with minimal symptoms and stable disease on imaging, may be managed with medical therapy initially. Non-surgical approaches include antiplatelet medications such as aspirin to reduce stroke risk, careful management of blood pressure and other vascular risk factors, and seizure management if seizures occur. Regular follow-up imaging and clinical assessment are essential to detect disease progression. However, it is important to note that most patients eventually require surgical revascularization, as the disease is progressive.

Surgical Revascularization: The Primary Treatment

Surgery is the most effective treatment for moyamoya disease and is recommended for most symptomatic patients and many asymptomatic patients identified through screening. The goal of surgical treatment is to restore blood flow to brain tissue at risk by creating new blood vessels that bypass the narrowed arteries.

Surgical revascularization procedures include:

• Extracranial-Intracranial Bypass (EC-IC): the surgeon connects an artery from outside the skull (such as the superficial temporal artery) directly to a brain artery beyond the area of narrowing, restoring blood supply to the affected brain tissue
• Encephaloduroarteriosynangiosis (EDAS): the surgeon places an artery directly onto the brain surface, allowing it to develop new connections with brain vessels over time, thereby gradually restoring blood flow
• Encephalomyosynangiosis (EMS): muscle from the scalp is placed onto the brain surface to stimulate new vessel formation

These procedures may be performed together in a staged fashion to ensure adequate revascularization. Surgery reduces the risk of future stroke by restoring blood flow to the brain and preventing the cascade of progressive narrowing. Most patients undergoing surgical revascularization remain stable or improve over long-term follow-up.

Why Choose New Jersey Brain and Spine?

NJBS is ranked among the top 3 neurosurgery practices in the nation by Castle Connolly Medical Ltd. The practice maintains a comprehensive neurovascular program with subspecialty expertise in brain vascular disease. NJBS physicians have completed fellowship training in neurovascular surgery and endovascular intervention and manage high volumes of complex vascular cases across our Hackensack University Medical Center network.

NJBS serves patients across northern New Jersey with offices in Paramus, Hackensack, Montclair, Montvale, Annandale, and Englewood. The neurovascular team evaluates and manages more than 700 cerebrovascular cases per year, including aneurysm, stroke, arteriovenous malformations, and moyamoya disease. No referral is required to schedule a consultation. Reach out to us today.

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