What Causes Moyamoya Disease? Understanding Symptoms, Diagnosis, and Treatment Options
Moyamoya disease is a rare and progressive cerebrovascular disorder characterized by the narrowing or blockage of major arteries at the base of the brain, particularly affecting the internal carotid artery and its branches—the anterior and middle cerebral arteries. The name "moyamoya," which means "puff of smoke" in Japanese, was coined because the tangled network of tiny collateral vessels that form to compensate for the blocked arteries resemble a faint cloud on an angiogram.
Understanding the Root Causes of Moyamoya Disease
Although the exact cause of moyamoya disease remains unclear, researchers believe it may stem from a combination of genetic and environmental factors. A growing body of evidence suggests a hereditary component, with certain gene mutations—such as those in the RNF213 gene—being strongly associated with the condition, especially in East Asian populations where the disease is more prevalent.
In some cases, moyamoya occurs as a secondary condition linked to other underlying disorders such as neurofibromatosis type 1, sickle cell disease, or prior head trauma and radiation therapy. When it appears without any known trigger, it's classified as moyamoya disease; when linked to another condition, it's referred to as moyamoya syndrome.
How Moyamoya Affects Brain Function
The progressive stenosis or occlusion of key cerebral arteries severely restricts blood flow to vital regions of the brain. This chronic ischemia increases the risk of both ischemic strokes (caused by lack of oxygen) and hemorrhagic strokes (due to rupture of fragile collateral vessels). Common symptoms include transient ischemic attacks (TIAs), seizures, headaches, cognitive decline, and in children, developmental delays.
Because the brain attempts to reroute blood through a network of tiny, weakened vessels, these new pathways are prone to leaking or bursting, further elevating the danger of intracranial bleeding. Over time, repeated micro-strokes can lead to significant neurological impairment if left untreated.
Diagnosis and Imaging Techniques
Early diagnosis is critical for managing moyamoya effectively. Neurologists typically use advanced imaging tools such as magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), computed tomography (CT), and cerebral angiography to visualize the characteristic "puff-like" vascular patterns and assess the extent of arterial narrowing.
Cerebral angiography remains the gold standard for confirming the diagnosis, offering detailed views of blood vessel abnormalities and helping specialists plan appropriate interventions.
Treatment Approaches and Surgical Options
While there is currently no cure for moyamoya disease, surgical revascularization has proven highly effective in restoring blood flow and reducing stroke risk. The most common procedures include direct bypass surgery (such as superficial temporal artery to middle cerebral artery anastomosis) and indirect techniques like encephaloduroarteriosynangiosis (EDAS), which encourage the growth of new blood vessels over time.
These surgeries aim to bypass blocked arteries and enhance cerebral perfusion, significantly improving long-term outcomes. Postoperative care often involves antiplatelet therapy and regular monitoring through imaging studies to track vascular changes.
Lifestyle Management and Long-Term Outlook
Patients diagnosed with moyamoya require lifelong neurological follow-up. Managing risk factors such as high blood pressure, avoiding smoking, staying hydrated, and minimizing activities that cause sudden changes in blood pressure (like excessive straining) can help reduce complications.
With timely intervention and proper management, many individuals with moyamoya disease can lead active, fulfilling lives. Ongoing research into genetic markers and novel therapies offers hope for earlier detection and more targeted treatments in the future.