Moyamoya Disease
Moyamoya disease is a rare cerebrovascular disorder marked by progressive narrowing of the main brain arteries and a compensatory network of fine, tortuous collateral vessels. It tends to cause ischemic events in children and hemorrhagic events in adults.
Last updated: 2026-06-07
Definition
Moyamoya disease is a chronic, progressive cerebrovascular disorder characterized by progressive narrowing/occlusion of the terminal internal carotid artery on both sides and the proximal segments of neighboring brain arteries, with a compensatory network of abnormal collateral vessels (moyamoya vessels). 'Moyamoya' is Japanese for something 'hazy, like a puff of smoke', describing the fine, tortuous vessels seen on angiography. It is more common in East Asian populations.
Causes and Classification
Thickening of the inner vessel-wall layer progressively narrows the lumen; the process is non-inflammatory. A genetic predisposition is linked to the RNF213 gene variant, especially in East Asians. The disease is grouped into primary (idiopathic) moyamoya disease of unknown cause and moyamoya syndrome arising from an underlying condition (such as prior radiotherapy, neurofibromatosis type 1, Down syndrome or sickle cell anemia). Angiographic progression is described by the Suzuki staging system.
Symptoms
Symptoms differ by age. In children an ischemic picture predominates: transient ischemic attacks, stroke, headache, seizures and cognitive decline with falling school performance; hyperventilation-provoking situations such as crying or blowing on hot food may trigger attacks. In adults, intracranial hemorrhage is more frequent and may present with sudden severe headache, nausea and vomiting, loss of consciousness or focal neurological deficits.
Diagnosis
First-line assessment is brain MRI with MR angiography, showing bilateral arterial narrowing, the collateral vessel network and signs of chronic ischemia. Digital subtraction angiography (DSA) is the gold standard and demonstrates the characteristic 'puff of smoke' appearance and the disease stage. SPECT or PET can assess cerebral blood flow and vascular reserve, which informs surgical planning. The differential diagnosis includes atherosclerosis, vasculitis and arterial dissection.
Treatment
The mainstay of treatment is surgical revascularization; medical therapy addresses symptoms but does not halt progression. Two surgical approaches are used to increase brain blood flow: direct bypass (a direct anastomosis between the superficial temporal artery and a cortical brain vessel) and indirect bypass (placing vascularized tissue layers onto the brain surface so that new vessels form over time). Indirect or combined methods are favored in children, while direct bypass is often used in adults.
Prognosis
Left untreated, the disease can progress with recurrent stroke, cognitive decline and disability. Surgical revascularization increases cerebral blood flow and substantially lowers the risk of stroke and hemorrhage, improving the disease course. Postoperative conditions such as transient hyperperfusion may occur and require careful monitoring. Early diagnosis and treatment improve prognosis; outcomes vary by patient and cannot be guaranteed.
References
- Greenberg MS. Greenberg's Handbook of Neurosurgery. 10th ed. Thieme; 2023:1581-1585.
- Winn HR, ed. Youmans Neurological Surgery. 6th ed. Saunders; 2011:3689-3697.
- Spetzler RF, Kalani MYS, Nakaji P, eds. Neurovascular Surgery. 2nd ed. Thieme; 2015:1156-1163.
- Scott RM, Smith ER. Moyamoya Disease and Moyamoya Syndrome. N Engl J Med. 2009.
- Research Committee on Moyamoya Disease (Japan). Guidelines for Diagnosis and Treatment of Moyamoya Disease. Neurol Med Chir. 2012.
This article is for general information and does not replace a medical examination. Diagnosis and treatment decisions are individual.