Moyamoya disease

What is Moyamoya Disease?

Moyamoya is a rare, progressive condition in which the arteries at the base of the skull—especially the internal carotid arteries—gradually narrow. This reduces blood flow to the brain, prompting the body to form a network of small, fragile blood vessels that appear as a “puff of smoke” on angiographic imaging. This phenomenon is called “moyamoya” in Japanese.

Moyamoya disease is more common in East Asian populations but occurs worldwide. It is typically diagnosed in children or adults between the ages of 30 and 40. The disease is associated with genetic factors, particularly the RNF213 gene.

Symptoms

Symptoms vary by age and may present differently.

• In children: transient ischemic attacks (TIAs or “mini-strokes”) often triggered by crying or hyperventilation; weakness on one side of the body, seizures (epilepsy), or headaches.

• In adults: ischemic strokes (cerebral infarctions), TIAs, hemorrhagic strokes (brain bleeds), visual disturbances, cognitive impairments (thinking, perception, memory), and frequent migraine-like headaches possibly linked to vascular narrowing and reduced blood flow.

Diagnosis

Main imaging methods include:

• MRI and MRA of the brain: Detects brain changes such as prior strokes and arterial narrowing.

• DSA (Digital Subtraction Angiography): The gold standard for confirming vessel narrowing or occlusion and visualizing the “puff of smoke” phenomenon. Crucial for treatment planning.

• CTA (CT Angiography): Often the first test performed when stroke is suspected. If Moyamoya is suspected, MRI/MRA and DSA follow. CTA is essential for surgical planning.

Treatment

Moyamoya disease is not curable. Treatment (surgery) aims to slow symptom progression, reduce intracranial hemodynamic stress, and lower the risk of ischemic or hemorrhagic events.

Medications:

• Aspirin (Thrombo ASS, Hjertemagnyl, “heart aspirin”): Prevents platelet aggregation and clot formation. Despite mixed research findings, most treatment centers recommend aspirin for patients with ischemic symptoms.

• Calcium channel blockers (Verapamil, Nimotop): May relieve headaches but are rarely prescribed due to stroke risk from low blood pressure.

• Anticoagulants (Orfarin, Xarelto, Lixiana): Affect clotting proteins. Rarely used due to bleeding risk outweighing benefits.

Surgery:

• Direct revascularization: Most common in adults. Involves extracranial-intracranial bypass—surgically connecting scalp arteries to brain arteries to improve blood flow and reduce stroke risk. Studies show stroke rates drop from 65% (medication only) to 17% (surgery) over five years. Early surgery is recommended for symptomatic patients.

• Indirect revascularization: No direct artery suturing. Well-perfused tissues (e.g., dura mater, temporal muscle, or small artery branches) are placed on the brain surface to promote new vessel growth. Commonly used in children due to small vessel size; in adults, used as an adjunct or fallback method.

Prognosis

Prognosis depends on symptom severity and stroke history. Two-thirds of symptomatic patients without surgery experience worsening symptoms within five years, often recurrent strokes. Surgery improves outcomes, especially for ischemic strokes. With timely treatment—especially in children—symptoms may significantly reduce or disappear, allowing for a full life. Prognosis is generally worse in cases of hemorrhagic stroke.

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