What Is Moyamoya Disease? Understanding Symptoms, Causes, and Treatment Options

Moyamoya disease is a rare and progressive cerebrovascular disorder characterized by the gradual narrowing or complete blockage of key arteries at the base of the brain. Specifically, it affects the internal carotid arteries and their major branches, including the anterior and middle cerebral arteries—and sometimes even the beginning segments of the posterior cerebral arteries.

How Moyamoya Disease Develops

The condition leads to reduced blood flow to vital regions of the brain. In response, the body attempts to compensate by forming a network of tiny, fragile collateral blood vessels near the base of the brain. These small vessels appear as a hazy cluster on angiograms—resembling a puff of smoke, which inspired the name "moyamoya," derived from the Japanese phrase meaning "puff of smoke." This distinctive visual pattern is a hallmark diagnostic feature of the disease.

Symptoms and Clinical Presentation

Patients with moyamoya may experience a range of neurological symptoms depending on age and disease progression. In children, common signs include transient ischemic attacks (TIAs), seizures, headaches, and developmental delays. Adults are more likely to present with hemorrhagic strokes due to the rupture of the abnormal blood vessel networks. Other possible symptoms include cognitive decline, speech difficulties, and involuntary movements.

Causes and Risk Factors

The exact cause of moyamoya disease remains unclear, but researchers believe genetic factors play a significant role. It is more prevalent in East Asian populations, particularly in Japan and Korea, suggesting a possible hereditary component. Some cases are also associated with other conditions such as neurofibromatosis type 1, sickle cell disease, or prior cranial radiation therapy, which are then classified as moyamoya syndrome rather than the primary disease.

Diagnosis and Imaging Techniques

Accurate diagnosis typically involves advanced imaging studies. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) help visualize blood flow and structural changes in the brain. Digital subtraction angiography (DSA) remains the gold standard for confirming the presence of the characteristic "smoky" vascular network and assessing the extent of arterial stenosis.

Treatment Approaches and Prognosis

While there is no cure for moyamoya disease, various treatment strategies aim to restore cerebral blood flow and prevent stroke. Revascularization surgery—such as direct bypass (e.g., superficial temporal artery to middle cerebral artery anastomosis) or indirect procedures (like encephaloduroarteriosynangiosis)—is often recommended, especially in pediatric patients. These surgeries promote the growth of new blood vessels and significantly reduce the risk of future ischemic events.

With timely diagnosis and appropriate intervention, the long-term prognosis for individuals with moyamoya disease is generally favorable. Stroke-related mortality rates are relatively low, particularly when managed by a specialized neurovascular team. Ongoing monitoring and lifestyle adjustments, including blood pressure control and avoiding dehydration, are essential components of comprehensive care.