Authored by Vince Murdock, moyamoya survivor and the Miles for Moyamoya team. Sources cited inline and listed in full at the page bottom. Last updated: 25 May 2026.
Moyamoya presents quite differently in children and adults. Understanding which pattern fits a given patient is central to suspecting the diagnosis.
The disease shows a bimodal age distribution: a paediatric incidence peak at 5 to 10 years and an adult peak at 30 to 50 years. The clinical pattern at each peak is distinct enough that clinicians often think of moyamoya as effectively two different diseases.
Children almost exclusively present with cerebral ischemia (not enough blood reaching the brain). Adults can present with ischemia, hemorrhage (bleeding inside the brain), or both. Adults are about seven times more likely than children to present with intracranial hemorrhage (20% vs 2.8% in a large US series). Adult hemorrhages typically come from rupture of the fragile collateral vessels the brain has grown in response to the arterial narrowing, or from associated saccular aneurysms.
The most common initial symptom is a transient ischemic attack (TIA) producing transient hemiparesis, aphasia, sensory disturbance, or a visual deficit lasting minutes to hours. Recurrent TIAs and completed ischemic strokes are typical.
Paediatric ischemic events are frequently triggered by hyperventilation. When a child breathes off carbon dioxide quickly, the resulting hypocapnia constricts cerebral vessels that are already compromised. Common triggers include crying or screaming, blowing wind instruments, vigorous exercise or sport, eating hot food (blowing on it), and dehydration.
A child with weakness, slurred speech, or visual changes after crying, exercise, or blowing on food deserves cerebrovascular imaging.
Adult moyamoya splits roughly 50/50 between ischemic and hemorrhagic strokes in Asian populations. In the US, ischemic symptoms still dominate, but adults bleed far more often than children.
Adult moyamoya can also present more insidiously with progressive cognitive decline, executive dysfunction, and headache without a clear stroke event. Because these symptoms are common in many other conditions, the patient often cycles through several specialists before someone orders the angiography that confirms moyamoya. The 2023 AHA/ASA Scientific Statement emphasises that any unexplained stroke or TIA in an adult under 50 should prompt consideration of moyamoya, particularly if standard atherosclerotic risk factors are absent.
62%
MISDIAGNOSED
The average patient is told it's anxiety, migraines, cerebral vasculitis, or ill-defined stroke before someone orders the imaging that confirms moyamoya. Mean delay: 5.28 years.
See treatment options →In the largest Caucasian case series of moyamoya patients, more than three in five were initially given the wrong diagnosis. The average delay to a correct diagnosis was over five years.
A 2019 retrospective study (Misdiagnoses and Delay of Diagnoses in Moyamoya Angiopathy, J Neurol 2019) reviewed 192 patients ultimately diagnosed with moyamoya. Of those, 119 (62%) had been initially misdiagnosed. The mean delay from first symptom to correct diagnosis was 5.28 years (median 3 years). The most common incorrect diagnoses:
The pattern reflects low clinical awareness outside specialist cerebrovascular centres, particularly in non-Asian populations where moyamoya is rarely included in the differential. Children and young adults who present with stroke without traditional vascular risk factors are especially vulnerable to the diagnostic delay.
Vince's diagnosis came through a different route. His left internal carotid was 100% blocked when imaging required by the Minnesota athletic commission found it before his fight. He was, in his own words, lucky: he could have died in training instead.
If any of these are true, ask for MRI plus MRA. If a TIA or stroke has already occurred, ask whether digital subtraction angiography (DSA) is appropriate.
If the diagnosis remains unclear after MRI/MRA, ask for referral to a centre with moyamoya expertise. Higher-volume centres are more likely to consider the diagnosis and have access to DSA, perfusion imaging, and the multidisciplinary teams needed to plan treatment.
Symptoms are one of four pages in our moyamoya cluster.
What moyamoya is, demographics, and how it affects the brain.
Direct vs indirect bypass, Suzuki staging, US treatment centres.
Post-bypass timeline, return to activity, stroke recurrence data.
The information on this page is for awareness and education and is not a substitute for professional medical advice, diagnosis, or treatment. If you suspect moyamoya, consult a neurologist or cerebrovascular specialist. See our editorial policy for how we source and review content.
In children, the first sign is almost always an ischemic event: a transient ischemic attack (TIA) or completed stroke, often triggered by crying, exercise, or hyperventilation. In adults, presentation can be ischemic or hemorrhagic. The 62% misdiagnosis rate means symptoms are often attributed to other causes first.
Children almost always present with ischemic events (TIAs, strokes, sometimes seizures). Adults are about seven times more likely than children to bleed (intracranial hemorrhage) and commonly present with sudden severe headache, ischemic stroke, or hemorrhagic stroke. Both groups can have cognitive decline.
Most clinicians never see a case. US prevalence is about 0.086 per 100,000, so moyamoya is rarely included in the differential. Symptoms mimic more common conditions (cerebral vasculitis, ill-defined stroke, multiple sclerosis). Mean time to correct diagnosis in one large series was 5.28 years.
Both children and adults can have moyamoya-related headaches, often migrainous in character. Adult presentations can include sudden thunderclap headache associated with intracranial hemorrhage. Persistent or progressive headaches in someone with a stroke history should prompt cerebrovascular imaging.
Red flags: a TIA or stroke in someone under 50, recurrent unexplained TIAs, a stroke with no typical vascular risk factors, neurological symptoms triggered by hyperventilation in a child, or a relative of someone with confirmed moyamoya. Ask for MRI plus MRA at minimum.
Moyamoya is missed because most clinicians never see it. Sharing this page is awareness. Supporting research accelerates the day better diagnostics and treatments arrive.