What is Moyamoya?
Moyamoya disease is a condition in which the major arteries at the base of the brain become progressively narrowed or blocked, reducing normal blood flow to the brain.
In response, the brain develops a network of small, fragile collateral vessels to compensate. On angiography, these tiny vessels create a characteristic appearance often described as a “puff of smoke,” which is what “moyamoya” means in Japanese.
Why is Accurate Diagnosis Important?
Diagnosis of moyamoya requires detailed imaging and careful evaluation.
Key studies include:
- MRI/MRA to assess areas of reduced blood flow or prior strokes
- CT angiography to evaluate vessel anatomy
- Cerebral angiography (catheter-based), which remains the gold standard for diagnosis and surgical planning
A thorough radiographic and angiographic evaluation is essential to:
- Confirm the diagnosis
- Determine severity
- Guide treatment decisions
What Are the Risks?
Moyamoya is a progressive condition that can significantly increase the risk of:
- Ischemic stroke (lack of blood flow to the brain)
- Hemorrhagic stroke (bleeding from fragile collateral vessels)
Without appropriate management, patients may face an ongoing risk of recurrent strokes over time.
Symptoms
Symptoms can vary, but often relate to reduced or unstable blood flow to the brain.
Common symptoms include:
- Transient weakness or numbness
- Speech difficulties
- Vision changes
- Headaches
In some patients, symptoms can be blood pressure–dependent, meaning that drops in blood pressure or dehydration may worsen cerebral blood flow and trigger neurological symptoms.
Treatment Options
Treatment of moyamoya is focused on restoring adequate blood flow to the brain and reducing stroke risk.
Medical management alone is often not sufficient in symptomatic or progressive cases.
Surgical Revascularization
The primary treatment for moyamoya is surgical bypass, which creates new pathways for blood to reach the brain.
There are two main types:
Direct (Open) Bypass
This involves directly connecting a scalp artery (such as the superficial temporal artery) to a brain artery.
- Provides immediate improvement in blood flow
- Often preferred in appropriately selected patients
- Requires microsurgical expertise
Indirect Bypass
Involves placing vascularized tissue near the brain surface, allowing new blood vessels to gradually grow into the brain over time.
- Blood flow improvement occurs more gradually
- May be used in selected cases or specific patient populations
Why Surgical Approach Matters
The choice between direct and indirect bypass depends on multiple factors, including:
- Patient age
- Vascular anatomy
- Severity of disease
- Surgeon experience
A tailored approach is critical to achieving the best outcome.
Our Approach
We take a comprehensive and individualized approach to moyamoya disease.
Evaluation includes detailed radiographic and angiographic analysis to fully understand each patient’s vascular anatomy and risk profile.
When surgery is indicated, we emphasize revascularization strategies that provide reliable and durable blood flow, with a strong focus on direct (open) bypass techniques when appropriate, while also incorporating indirect methods when beneficial.
Our goal is to reduce stroke risk and improve long-term cerebral blood flow, using precise microsurgical techniques and careful patient selection.
View the approach