EMERGENCY:Child or young adult with sudden weakness, speech difficulty, or collapse? This may be a stroke from Moyamoya disease —call040-46324365immediately — 24 hours, 7 days— 24/7
Moyamoya Disease: When the Brain's Main Arteries Slowly Close — and Why Bypass Surgery Changes Everything
Moyamoya disease is a progressive cerebrovascular disorder in which the major arteries supplying the brain particularly the internal carotid arteries gradually narrow and close over time. As blood flow decreases the brain attempts to compensate by forming a fragile network of tiny collateral blood vessels at the base of the brain. On angiography these abnormal vessels resemble a puff of smoke the Japanese term "moyamoya" from which the disease takes its name.
Progressive narrowing of the main brain arteries causing stroke and TIA in children and young adults
Japanese for puff of smoke describing the appearance of collateral vessels on angiography
Children peak age 3 to 8 years and adults peak 41 to 45 years with female predominance
040 46324365 24 hours
15.3 percent of all childhood strokes in India are caused by Moyamoya
Progressive strokes cognitive decline and disability
Bypass surgery redirecting blood supply to the oxygen starved brain
Moyamoya disease is a progressive cerebrovascular disorder in which the internal carotid arteries — the main arteries supplying the brain — gradually narrow and eventually block. The brain attempts to compensate by forming a fragile network of tiny collateral vessels visible on angiography as a "puff of smoke" — the Japanese meaning of "moyamoya." Moyamoya causes ischemic strokes and TIAs in children and haemorrhagic strokes in adults. In India, 15.3% of all childhood strokes are caused by Moyamoya. The definitive treatment is bypass surgery: direct STA-MCA bypass, which reduces future stroke risk by 74%. At KIMS Neuroscience Hyderabad, Moyamoya bypass surgery is performed for both paediatric and adult patients.
- What it is
- Progressive narrowing of the main brain arteries. Tiny fragile compensatory vessels form ("puff of smoke" on angiography). Causes strokes in children and young adults.
- India stat
- 15.3% of ALL childhood strokes in India are caused by Moyamoya. One in seven childhood strokes. It is not rare in India — it is regularly missed because it is not considered.
- Childhood warning pattern
- A child who develops weakness or speech difficulty during crying, blowing, or exercise — then recovers — may have Moyamoya TIA. Hyperventilation constricts already critically narrowed arteries.
- Adult presentation
- More often haemorrhagic (fragile collateral vessels rupture). Young adult with stroke-like events, no conventional risk factors. Moyamoya must be investigated.
- Definitive treatment
- Direct STA-MCA bypass surgery: scalp artery connected to brain artery, immediately rerouting blood supply. Reduces stroke risk by 74% vs conservative treatment.
- Children vs adults
- Children: indirect bypass (synangiosis) · robust neovascularisation over 3–6 months · Adults: direct or combined bypass (immediate + sustained revascularisation).
- Contact KIMS
- 040-46324365 (acute stroke emergency) · 040-44885000 (Moyamoya consultation) · Bypass surgery for children and adults
| Fact | Details |
|---|---|
| Name meaning | "Puff of smoke" in Japanese — describes the appearance of compensatory collateral vessels on cerebral angiography |
| India burden | 15.3% of childhood strokes · 1.56% of all stroke/TIA patients · Bimodal: children 3–8 years, adults 41–45 years · Female predominance (1:1.4) |
| Paediatric presentation | Ischemic TIA/stroke triggered by hyperventilation (crying, blowing) · Recurrent arm or leg weakness during specific activities |
| Adult presentation | Haemorrhagic stroke more common (fragile collateral vessels rupture) · Progressive cognitive decline · Recurrent headaches |
| Diagnosis | MRI/MRA (narrowing + smoke sign) · DSA gold standard (Suzuki staging 1–6) · Cerebral perfusion imaging guides which territory to revascularise |
| Bypass surgery | STA-MCA direct bypass (adults · immediate revascularisation) · EDAS indirect (children · neovascularisation over 3–6 months) · Combined · 74% stroke risk reduction |
| Long-term | Progressive disease · Serial MRI/MRA and perfusion imaging · Antiplatelet therapy · Avoid dehydration, hyperventilation, extreme exertion |
About This Condition
What Is Moyamoya Disease?
In 1957 Japanese radiologists described a pattern of cerebral angiography unlike anything they had seen before. The main arteries at the base of the brain the internal carotid arteries and their branches were narrowing and closing. And in response the brain had grown a chaotic tangle of tiny new vessels trying to compensate for the lost blood supply. On the angiogram this tangle looked like a cloud of smoke rising from the base of the brain. The radiologists named it Moyamoya Japanese for puff of smoke.
Moyamoya disease is a chronic progressive condition in which the terminal portions of the internal carotid arteries the main arteries supplying blood to most of the brain gradually narrow and eventually block. As they close the brain attempts to compensate by developing a network of tiny collateral vessels. These fragile abnormal vessels are inadequate substitutes. They cannot carry enough blood to maintain normal brain function under stress. And they are prone to rupture.
The result is a brain under constant threat. In children the reduced blood supply causes ischaemic strokes and TIAs classically triggered by crying hyperventilation or physical activity that cause changes in blood gas levels. In adults the fragile collateral vessels are more prone to rupture haemorrhagic stroke is the more common presentation in adult Moyamoya.
In the largest Indian Moyamoya cohort MMA accounted for 1.56 percent of all stroke and TIA patients and 15.3 percent of all childhood stroke presentations. One in seven childhood strokes in India is caused by Moyamoya. This is not a disease seen only in Japan. It is a significant cause of stroke in Indian children and it is regularly missed because it is not on the differential diagnosis until a specialist considers it.
At KIMS Neuroscience Secunderabad Hyderabad Moyamoya disease is diagnosed and surgically treated by the KIMS Neuroscience team. Cerebral bypass surgery the definitive treatment is available for both paediatric and adult patients.
Book Moyamoya Consultation
Our cerebrovascular and Moyamoya team is available for urgent, emergency :
040-46324365International enquiries: neuroscience@kimshospitals.comWhy Moyamoya Happens
The underlying disease process
The precise cause of Moyamoya disease is not fully understood. It is not caused by atherosclerosis the fatty plaque build up that causes most adult strokes. It is an idiopathic progressive vasculopathy in which the arterial walls thicken and narrow due to a process that is still being investigated.
Genetic factors
Recent genetic studies have identified RNF213 as an important susceptibility gene for Moyamoya disease particularly in East Asian populations. The RNF213 mutation is less prevalent in Indian patients than in Japanese or Korean patients consistent with clinical data showing somewhat different presentations in Indian cohorts. Other gene mutations including GUCY1A3 loss of function have also been identified. Moyamoya disease can run in families approximately 10 to 15 percent of cases in East Asian populations have a familial pattern.
Moyamoya syndrome secondary causes
When Moyamoya pattern arterial narrowing is found in association with another recognised condition it is called Moyamoya syndrome rather than Moyamoya disease.
Important associated conditions include:
• Sickle cell disease
• Down syndrome (trisomy 21)
• Neurofibromatosis type 1
• Prior cranial radiation (particularly in childhood brain tumour survivors)
• Thyroid disorders
• Certain autoimmune conditions
These associated conditions are systematically excluded at KIMS before a diagnosis of primary Moyamoya disease is made.
Demographic pattern in India
In the Indian Moyamoya cohort a female predominance was noted with a male to female ratio of 1 to 1.4 and a bimodal age distribution first peak at ages 3 to 8 years and a shorter second peak at ages 41 to 45.
The median age at onset in the Indian cohort was 17.5 years with the youngest patient aged 10 months. This is overwhelmingly a disease of the young.
How Does Moyamoya Present? Recognising the Symptoms
The clinical presentation of Moyamoya differs significantly between children and adults.
In Children — Ischaemic Presentation Dominates
Among children in the Indian Moyamoya cohort, the predominant first neurological symptom was fixed motor weakness (44%), followed by TIA (26.7%), seizures (17.3%), and headache (9.3%).
The hallmark paediatric presentation is recurrent TIA or stroke events triggered by hyperventilation or exertion. A child who has strokes or TIAs during crying, blowing balloons, eating hot food triggering hyperventilation, or physical activity should be investigated urgently for Moyamoya. The hyperventilation lowers blood carbon dioxide levels, causes cerebral vasospasm, and reduces blood flow in already critically narrowed arteries pushing a brain that is barely compensating over the edge into ischaemia.
Parents often notice that their child repeatedly develops a limp on one side, or weakness of one arm, during specific activities then recovers. This intermittent, activity triggered pattern is strongly suggestive of Moyamoya in a child.
Specific childhood presentations to recognise :
• Recurrent episodes of weakness or numbness on one side arm, leg, or face
• Transient speech difficulty
• Seizures
• Deteriorating school performance and cognitive difficulties as cumulative ischaemic damage accumulates
• Headaches sometimes severe from the abnormal collateral vessels
In Adults — Haemorrhagic Presentation Is More Common
Adult patients with Moyamoya are nearly twice as likely to present with intracranial haemorrhage compared to paediatric patients. The fragile collateral vessels strained by years of carrying the blood supply that should have flowed through normal arteries rupture.
The clinical picture is haemorrhagic stroke in a young adult headache, sudden weakness, or collapse without the usual risk factors of hypertension or vascular disease explaining it.
Adults also present with ischaemic TIAs and stroke, progressive cognitive decline, and recurrent headaches.
Important Clinical Point
In any adult under 50 with recurrent stroke or TIA without a clear conventional explanation, Moyamoya must be investigated.
Diagnosis at KIMS
Diagnosis — How Moyamoya Is Confirmed at KIMS
Moyamoya has a characteristic appearance on cerebrovascular imaging and the diagnosis is made radiologically.
MRI and MRA Magnetic Resonance Angiography
MRI of the brain identifies prior strokes white matter changes and signs of ischaemia. MRA of the cerebral arteries shows the narrowing of the internal carotid arteries and the proximal anterior and middle cerebral arteries and characteristic of Moyamoya the presence of the compensatory collateral vessels appearing as flow voids at the base of the brain. This MRA pattern is often sufficient to strongly suggest the diagnosis. CT angiography provides rapid vascular imaging in the acute setting.
Digital Subtraction Angiography DSA — The Gold Standard
Four-vessel cerebral DSA remains the definitive investigation for Moyamoya. It precisely demonstrates the degree of stenosis, the extent of collateral formation, and the Suzuki angiographic stage the grading system for Moyamoya severity from Stage 1 (early narrowing) to Stage 6 (complete obliteration with disappearance of the collateral network). DSA is essential for surgical planning.
Cerebral Perfusion Imaging
MR perfusion or SPECT Single Photon Emission Computed Tomography identifies areas of brain at risk regions with reduced blood flow that have not yet infarcted but are ischaemic under stress. Perfusion imaging at KIMS guides the decision about which brain territory to revascularise first and demonstrates the improvement in cerebral blood flow achieved after surgery.
The Suzuki Grading System
| Stage | Angiographic Finding |
|---|---|
| Stage 1 | Narrowing at the carotid fork only |
| Stage 2 | Initiation of moyamoya vessels early collateral formation |
| Stage 3 | Intensification of moyamoya vessels established collateral network |
| Stage 4 | Minimisation of moyamoya vessels beginning to reduce |
| Stage 5 | Reduction of moyamoya vessels further attenuation |
| Stage 6 | Disappearance of moyamoya vessels end stage |
Stages 3 to 4 represent the critical period for intervention before end stage disease eliminates the surgical revascularisation options. Early diagnosis and timely bypass surgery can significantly reduce the risk of recurrent stroke progressive neurological disability and cognitive decline.
Treatment
Treatment — Bypass Surgery at KIMS
Surgical revascularisation remains the definitive treatment for Moyamoya disease by augmenting flow to the hypoperfused brain. In patients with symptomatic Moyamoya disease bypass surgery is significantly more effective than conservative treatment in preventing future strokes.
The goal of bypass surgery in Moyamoya is not to repair the diseased arteries they cannot be repaired. The goal is to create a new blood supply pathway routing healthy blood into the brain territory that the Moyamoya arteries can no longer adequately perfuse.
Surgical Option 1 : Direct Bypass STA MCA Bypass
Direct bypass the most immediately effective revascularisation procedure involves connecting the superficial temporal artery STA a scalp artery running in front of the ear directly to a branch of the middle cerebral artery MCA on the brain surface. After the anastomosis surgical connection is complete blood flows immediately and directly from the scalp circulation into the brain bypassing the blocked internal carotid artery entirely.
The advantages of direct bypass :
Immediate revascularisation blood flow to the ischaemic brain is augmented on the day of surgery. In adults with Moyamoya direct bypass is the preferred technique. Direct bypass appears to reduce stroke risk more than indirect bypass in adult Moyamoya patients.
Technical demands :
Direct bypass in Moyamoya is one of the most technically demanding operations in all of cerebrovascular neurosurgery. The recipient MCA branches are typically very small often 1 to 1.5 mm in diameter. The anastomosis requires microsurgical suturing under high magnification with absolute precision. The surgery is performed with intraoperative neuromonitoring and intraoperative flow measurement transit time flowmetry to confirm the bypass is functioning and providing adequate cerebral blood flow before the skull is closed.
Surgical Option 2 : Indirect Bypass Synangiosis
Indirect bypass does not create an immediate direct connection between scalp and brain arteries. Instead the vascular tissue of the scalp the STA itself the temporalis muscle the dura mater or a combination is placed directly in contact with the brain surface. Over the following weeks and months new blood vessels grow from these tissues into the underlying brain gradually establishing a new collateral circulation.
The advantages of indirect bypass :
Technically less demanding than direct bypass. Particularly effective in children the paediatric brain has remarkable capacity for new vessel formation. Multiple variants are used EDAS encephalo duro arterio synangiosis EMS encephalo myo synangiosis and burr hole procedures. Children respond very well to indirect bypass with robust neovascularisation developing over 3 to 6 months.
Children respond well to indirect bypass whereas adults benefit more from direct and combined bypass procedures.
Surgical Option 3 : Combined Bypass
For many patients particularly adults a combined approach is used a direct STA MCA anastomosis for immediate revascularisation combined with indirect techniques such as EDAS to stimulate long term collateral growth. This provides both immediate and sustained blood flow improvement to the ischaemic brain territory.
Medical Management Supportive Not Curative
Antiplatelet therapy low dose aspirin reduces the risk of thromboembolic events in the narrowed Moyamoya vessels and is used in all Moyamoya patients who have not been surgically treated. However aspirin does not prevent disease progression does not improve cerebral blood flow and does not substitute for surgery in symptomatic patients.
Outcomes After Bypass Surgery
The evidence for bypass surgery in Moyamoya is clear and consistent.
Bypass surgery reduces the risk of future stroke in symptomatic Moyamoya patients compared to conservative treatment with an odds ratio of 0.26 indicating a 74 percent reduction in stroke risk.
In children bypass surgery prevents the accumulation of further ischaemic injury protects cognitive development and allows children to return to normal schooling and activities.
In adults with haemorrhagic Moyamoya bypass surgery reduces the elevated rebleed risk from the fragile collateral vessels by providing an alternative more robust blood supply pathway that reduces the haemodynamic stress driving collateral rupture.
For both groups surgery is most effective when performed before extensive ischaemic damage has accumulated reinforcing the importance of early diagnosis.
What to Expect — Monitoring and Long Term Care
Moyamoya is a progressive disease. Bypass surgery stabilises and often dramatically improves cerebral perfusion but the underlying tendency toward arterial narrowing continues.
Long term follow up with serial MRI MRA and perfusion imaging is essential to monitor the status of the bypass the progression of the underlying disease and to assess whether further surgery to revascularise a different territory may be needed.
At KIMS Neuroscience every Moyamoya patient has a structured follow up programme MRI and MRA at 6 months post surgery then annually. Perfusion imaging is repeated at intervals determined by the clinical picture.
Children are followed through their neurological development cognitive assessment and educational support are part of the holistic programme.
Antiplatelet therapy is continued long term in most patients. Blood pressure is managed carefully both hypotension and hypertension can worsen cerebral perfusion in Moyamoya. Dehydration hyperventilation and extreme exertion are avoided.
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FAQs
Frequently Asked Questions
EMERGENCY:Child or young adult with stroke symptoms — possible Moyamoya emergency —call040-46324365immediately — 24 hours, 7 days— 24/7
Moyamoya bypass surgery at KIMS. Expert cerebrovascular care for children and adults in Hyderabad.
The KIMS Neuroscience cerebrovascular team provide complete Moyamoya management — MRI/MRA and DSA diagnosis, cerebral perfusion imaging, direct STA-MCA bypass, indirect synangiosis, combined revascularisation, and long-term neurological follow-up. The most experienced Moyamoya programme in Telangana and Andhra Pradesh.
neuroscience@kimshospitals.com