Moyamoya Disease & Syndrome
Moyamoya: At a Glance
What it is: Moyamoya is a rare, progressive cerebrovascular disorder where the main brain arteries become narrowed. The body forms tiny, fragile blood vessels to compensate for reduced blood flow.
How it affects people: These small vessels in the brain can easily become blocked or rupture, leading to transient ischaemic attacks, strokes, or bleeding in the brain.
Key concern: Untreated Moyamoya can cause repeated stroke, long-term neurological problems, or cognitive decline.
Diagnosis: Usually confirmed with specialist brain imaging such as MRI, MRA, or cerebral angiography.
Treatment options: Medical management, surgical revascularisation procedures and long-term monitoring.
Outlook: With early diagnosis, most patients can stabilise their condition, improve cerebral blood flow, and reduce the risk of future strokes.
Moyamoya is a chronic, progressive cerebrovascular disorder affecting the arteries at the base of the brain, particularly the internal and external carotid arteries and their branches.
As these arteries narrow, the body tries to compensate by developing a network of small, fragile vessels, described in Japanese as “moyamoya”, meaning “a puff of smoke” on imaging scans.
These fragile vessels are inefficient and prone to blockage or rupture, leading to symptoms such as stroke, seizures, or headaches. Moyamoya can occur in both children and adults, though its presentation and progression often differ depending on the side of the body affected.
What is Moyamoya Disease?
There are two main classifications:
Moyamoya disease:
Primary, idiopathic form with no clear underlying cause.
Moyamoya syndrome:
Secondary to other medical conditions or previous radiation exposure.
Symptoms of Moyamoya
Symptoms vary depending on age, severity, and the area of the brain affected.
Common symptoms include:
Recurrent transient ischaemic attack (TIA) episodes
Stroke with weakness or paralysis on one side of the body
Headaches or migraines
Seizures
Cognitive or developmental delays (in children)
Vision changes or speech difficulties
Red flag symptoms that require urgent medical attention:
Sudden severe headache
Loss of consciousness
Sudden weakness or numbness
Difficulty speaking or understanding speech
Call 999 immediately if you experience these symptoms.
Prompt diagnosis and specialist assessment are critical to prevent further neurological injury.
Causes and Who Is at Risk
Causes of Moyamoya
The exact causes of Moyamoya are not fully understood, but research suggests both genetic and environmental medical conditions may play a role.
It is more common in East Asian populations but is increasingly recognised worldwide.
Potential risk factors include:
Moyamoya disease:
Potential risk factors include a family history of Moyamoya and genetic mutations, most commonly involving the RNF213 gene.
Moyamoya syndrome:
It may be linked to conditions such as Down syndrome, neurofibromatosis type 1, or sickle cell disease, as well as previous cranial radiation therapy or certain autoimmune disorders.
Getting a Diagnosis
A Moyamoya diagnosis involves advanced imaging to evaluate narrowing of brain arteries and the presence of collateral vessels.
Common diagnostic tests include:
MRI and MRA (Magnetic Resonance Imaging / Angiography): Show narrowing of blood vessels in the brain and collateral circulation.
CT Angiography: Identifies parts of the brain affected by poor circulation and shows vessel walls and collateral networks.
Cerebral Angiogram: The gold standard for diagnosis, providing a detailed map of the affected arteries and vessels in the brain.
Perfusion Studies: Assess oxygen and blood delivery to different areas of the brain.
Early, accurate diagnosis ensures patients receive timely treatment and stroke prevention strategies.
Treatment Options for Moyamoya
Moyamoya treatment aims to restore blood flow to the brain and prevent further stroke. Management depends on the severity of artery narrowing and the patient’s overall health. Options include:
Medical Management
Controlling high blood pressure, using antiplatelet medications such as aspirin to prevent clot formation, and supporting lifestyle changes such as staying hydrated and avoiding smoking.
Monitoring
Regular scans (MRI or MRA) may be recommended to assess vessels in the brain and track disease progression in mild or early cases.
Surgical Treatment
Procedures designed to restore or improve cerebral blood flow such as direct revascularisation (bypass surgery) or indirect revascularisation.
Rehabilitation and Follow-up
After treatment, patients may undergo physiotherapy, occupational therapy, or speech therapy to support recovery. Regular imaging confirms stable blood flow and helps reduce the risk of future stroke.
Every patient’s case is carefully reviewed in collaboration with a neuroradiologist and a multidisciplinary team. This ensures all treatment options are considered and the safest, most effective plan is chosen.
These procedures are highly specialised and should be carried out by an experienced consultant. Mr Kailaya-Vasan, Consultant Neurosurgeon, specialises in neurovascular surgery and revascularisation for Moyamoya disease and syndrome, providing expert care for patients across London, the UK, and internationally.
Living with Moyamoya
Living with Moyamoya requires ongoing care and regular medical follow-up to maintain healthy blood flow and reduce the risk of future strokes. With expert management, most patients go on to live active, independent lives. After treatment, maintaining stable blood pressure, staying hydrated, and avoiding smoking or sudden changes in altitude can help protect brain function and circulation.
Regular neurological reviews and imaging scans are essential to monitor blood flow and detect any new vessel changes early. Rehabilitation therapies such as physiotherapy, occupational therapy, and speech therapy may also support recovery, particularly for patients who have experienced stroke-related symptoms.
For families with a known history of Moyamoya disease, genetic counselling can provide valuable guidance and help identify those at increased risk. Ongoing communication with a specialist care team ensures that each patient receives personalised advice and support to maintain long-term health and quality of life.
Book a consultation with Mr Ahilan Kailaya-Vasan
Receive a clear diagnosis and a tailored treatment plan from a leading consultant neurosurgeon. Appointments are available at top London hospitals, with remote options for international patients.
Seeking a second opinon?
If you have already received a diagnosis elsewhere, Mr Kailaya-Vasan can provide an independent review of your scans and medical notes, and explain the safest and most effective next steps.
FAQs about Moyamoya Disease and Syndrome
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In some cases, yes. Genetic mutations such as those affecting the arteries in the brain may contribute, especially in families with multiple affected members.
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Early signs include TIAs, headaches, or weakness on one side of the body due to reduced blood flow.
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Without treatment, recurrent strokes may cause lasting neurological damage. Surgical intervention restores vessels in the brain and reduces the risk of further injury.
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Most patients recover within weeks and continue to improve as blood flow increases in affected parts of the brain.
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It is considered rare in Western populations but more prevalent in East Asia. Awareness is increasing globally due to advances in imaging and diagnosis.
If you have any further questions, please get in touch.