Moyamoya disease is a rare cerebrovascular condition in which the main arteries at the base of the brain — especially the internal carotid arteries — gradually narrow or close.
To compensate, the brain develops a fragile network of tiny collateral vessels that resemble a “puff of smoke” on angiography (in Japanese, moyamoya means “hazy cloud”).
As the narrowing worsens, patients become prone to transient ischemic attacks (TIAs), strokes, or brain hemorrhage.
Modern microsurgical techniques such as indirect or direct cerebral bypass can restore blood flow and prevent further damage.
Symptoms
Moyamoya can appear in both children and adults, with differing symptoms:
In children:
- Repeated transient ischemic attacks (brief strokes)
- Weakness or numbness on one side of the body
- Difficulty speaking or understanding words
- Sudden fainting or jerking movements during crying or hyperventilation
- Learning or concentration problems due to chronic low blood flow
In adults:
- Stroke or brain hemorrhage
- Headaches or seizures
- Cognitive decline, confusion, or vision changes
- Occasionally, symptoms triggered by stress, fever, or dehydration
Diagnosis
Diagnosis begins with MRI and MRA, showing narrowed arteries and characteristic collateral networks.
The definitive test is digital subtraction angiography (DSA), which reveals the classic moyamoya vessels — fine collateral arteries at the base of the brain.
CT perfusion or SPECT scans may be used to measure blood flow and identify ischemic brain regions needing revascularization.
In children, genetic testing (RNF213 mutation) can support diagnosis.
Treatment Options
1. Indirect Bypass Surgery
The most common treatment, particularly in children, is indirect revascularization, where tissues rich in blood supply are placed in contact with the brain surface to encourage natural vessel growth.
Types include:
- EDAS (Encephalo-Duro-Arterio-Synangiosis): the superficial temporal artery (STA) is laid directly on the brain surface.
- EMS (Encephalo-Myo-Synangiosis): a piece of temporalis muscle is placed over the brain.
- EDAMS (Combined method): both artery and muscle are used to enhance new vessel formation.
These methods stimulate the gradual development of new collateral vessels over several months, improving brain perfusion safely.
2. Direct Bypass Surgery (STA–MCA Anastomosis)
In selected adults, a direct connection is made between the superficial temporal artery (STA) and a middle cerebral artery (MCA) branch under a microscope.
This provides immediate blood flow improvement, often combined with an indirect technique for long-term stability.
3. Medical Management
Before and after surgery, patients are treated with antiplatelet medications, hydration, and avoidance of hyperventilation or dehydration to prevent stroke recurrence.
Long-term follow-up is essential to monitor new vessel development.
Recovery & Follow-Up
After bypass surgery, patients are typically discharged within 3–5 days.
Mild headaches or fatigue are common in the first weeks.
New blood vessels develop progressively over 3–6 months — confirmed by follow-up MRI/MRA or angiography.
In children, early surgery often prevents further neurological decline and supports normal cognitive development.
Adults experience reduced stroke recurrence and better long-term function.
When to See a Neurosurgeon
If you or your child experiences recurrent transient weakness, mini-strokes, or unexplained neurological symptoms, evaluation by a cerebrovascular neurosurgeon is crucial.
Early revascularization dramatically reduces future stroke and disability risk.