Moyamoya Disease

Moyamoya disease is a rare, progressive cerebrovascular disorder characterized by narrowing of the distal internal carotid arteries and their main branches—the anterior cerebral artery and middle cerebral artery. The name “Moyamoya,” meaning “puff of smoke” in Japanese, was coined by Professor Suzuki in Japan because cerebral angiography shows a hazy, smoke-like appearance of abnormal collateral vessels.

The condition occurs more frequently in East Asians, particularly among Japanese and Korean populations, with an incidence of approximately 1 per 1,000,000 people. Moyamoya disease presents differently by age: in children, it typically manifests with cerebral ischemia or stroke, whereas in adults, intracranial hemorrhage is relatively common. For this reason, Moyamoya disease should always be considered in the differential diagnosis of both pediatric and adult stroke.

As the main arteries supplying the brain gradually narrow, small collateral vessels form to compensate. Before these collaterals are well developed, patients—especially children, whose brains require high blood flow—may experience various ischemic symptoms.

Characteristic early signs include transient weakness of the arms or legs after activities such as blowing on hot food, crying intensely, or playing wind instruments. Depending on the area of reduced blood supply, patients may present with:

• Motor deficits (hemiparesis or paralysis)
• Seizures
• Headache
• Involuntary movements
• Facial palsy
• Sensory disturbances
• Cognitive decline
• Visual field defects
• Speech or language difficulties

The exact cause of Moyamoya disease remains unknown. Hypotheses include autoimmune-mediated vasculitis, environmental factors, and genetic predisposition. However, no single cause has been definitively established. Because the disease results in progressive loss of cerebral vessels and reduced blood supply, avoiding conditions that exacerbate ischemia is important.

There are no proven preventive strategies, as the cause of Moyamoya disease is still unclear. Family members of affected individuals are advised to undergo screening, as familial cases have been reported.

Early recognition and treatment are crucial to preventing secondary neurological deficits. Individuals should consult a specialist if they experience sudden weakness or numbness in the limbs, recurrent headaches, seizures, or transient neurological symptoms triggered by crying, eating hot food, or exertion.