What Is Moyamoya Disease-Related Brain Hemorrhage?

Understanding Moyamoya Disease and Its Link to Stroke

Moyamoya disease is a rare, progressive cerebrovascular disorder characterized by the gradual narrowing and eventual blockage of key arteries at the base of the brain, particularly the internal carotid arteries and their major branches—the middle cerebral and anterior cerebral arteries. As these vital blood vessels become obstructed, the brain struggles to receive adequate oxygen, triggering the development of a fragile network of tiny collateral blood vessels. These minute vessels attempt to compensate for the reduced blood flow, forming what appears on angiograms as a hazy, smoke-like pattern—hence the name "Moyamoya," which means "puff of smoke" in Japanese.

Why Does Moyamoya Lead to Brain Hemorrhage?

The newly formed collateral vessels are structurally weak and prone to rupture, making them a significant risk factor for intracranial bleeding. This condition, known as Moyamoya-related hemorrhagic stroke, occurs when one or more of these delicate vessels burst, causing blood to leak into the surrounding brain tissue. Unlike typical ischemic strokes caused by blocked arteries, hemorrhagic events in Moyamoya patients stem from vessel fragility rather than clot formation. These bleeds can lead to severe neurological complications, including headaches, seizures, paralysis, and even life-threatening increases in intracranial pressure.

Risk Factors and Common Symptoms

Patients with Moyamoya disease may remain asymptomatic for years, but once symptoms appear, they often include transient ischemic attacks (TIAs), speech difficulties, vision problems, and motor weakness. In adults, hemorrhagic presentation is more common than in children, where ischemic symptoms tend to dominate. Genetic predisposition, certain autoimmune conditions, and coexisting vascular abnormalities may increase susceptibility. Early diagnosis through MRI, MRA, or cerebral angiography is crucial to managing the disease and preventing catastrophic bleeding episodes.

Treatment and Long-Term Management

While there is no cure for Moyamoya disease, surgical revascularization procedures such as direct or indirect bypass surgery can significantly reduce the risk of both ischemic and hemorrhagic strokes by improving cerebral blood flow. Medications like antiplatelets may be used cautiously, though they carry an increased bleeding risk in this population. Ongoing monitoring, lifestyle modifications, and prompt intervention during symptom onset are essential components of long-term care. With proper management, many patients can maintain a good quality of life and minimize the chances of severe complications like brain hemorrhage.