Moyamoya Disease: Why Bypass Surgery Is Preferred Over Stenting
Understanding Moyamoya Disease and Its Treatment Evolution
Since its initial discovery by Japanese medical experts in the 1950s, moyamoya disease has been the subject of extensive research and clinical investigation around the world. Over the past several decades, significant progress has been made in understanding this rare cerebrovascular condition and developing more effective treatment strategies. As awareness grows and diagnostic technologies advance, more cases are being identified earlier, improving patient outcomes across the globe.
The Challenge of Misdiagnosis and Inappropriate Treatments
Rising Detection Rates Due to Improved Imaging
In recent years, the increased availability of advanced neuroimaging techniques—such as magnetic resonance angiography (MRA) and digital subtraction angiography (DSA)—in hospitals worldwide has led to a higher detection rate of moyamoya disease. While still considered rare, it is no longer as frequently overlooked as it once was. However, due to its complex nature and relatively short history in medical science (less than 70 years), many healthcare providers, especially in non-specialized centers, lack sufficient expertise in accurately diagnosing and managing the condition.
One common misconception arises when clinicians observe arterial narrowing on brain scans and assume that standard interventional approaches—like stent placement—used for atherosclerotic disease—are appropriate. This leads some regional or general hospitals to attempt treating moyamoya with endovascular stenting, despite strong evidence against this practice.
Why Stenting Is Not Recommended for Moyamoya Patients
The Unique Pathology Behind the Condition
Moyamoya disease is characterized by progressive stenosis or occlusion of the internal carotid arteries and their major branches at the base of the brain. As these critical vessels narrow over time, the body attempts to compensate by forming a network of tiny collateral blood vessels. On angiograms, these fragile vessels appear like puffs of smoke—hence the name "moyamoya," which means "puff of smoke" in Japanese.
Stenting fails to address the underlying pathology because the disease often involves multiple sites of narrowing, sometimes diffusely spread across both sides of the circle of Willis. Placing one or even two stents cannot resolve widespread vascular involvement. Even if a proximal vessel is opened with a stent, distal segments may continue to deteriorate, leading to persistent ischemia.
More dangerously, the abnormal collateral vessels in moyamoya patients are extremely thin-walled and prone to rupture. The mechanical expansion caused by stent deployment can easily lead to catastrophic intracranial hemorrhage—a risk far outweighing any potential benefit. For these reasons, endovascular stenting is widely discouraged in the international neurosurgical community for moyamoya disease.
The Gold Standard: Cerebral Revascularization Through Bypass Surgery
Direct and Indirect Bypass Techniques
Today, cerebral revascularization via bypass surgery is recognized as the most effective long-term treatment for moyamoya disease. Among various surgical options, combined direct and indirect bypass procedures have shown superior results in restoring cerebral blood flow and preventing future strokes.
Our clinical team has extensive experience performing composite revascularization surgeries, combining direct superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis with indirect techniques such as encephaloduroarteriosynangiosis (EDAS) or encephalomyosynangiosis (EMS). This dual approach creates both immediate and gradual formation of new blood supply pathways to the ischemic brain regions.
Long-Term Benefits of Surgical Intervention
By establishing stable collateral circulation, bypass surgery significantly improves cerebral perfusion, reduces the frequency of transient ischemic attacks (TIAs), and lowers the risk of hemorrhagic or ischemic stroke. Long-term follow-up studies show that patients who undergo timely revascularization enjoy better cognitive function, improved quality of life, and reduced need for repeated hospitalizations.
Moreover, modern microsurgical techniques and perioperative management have greatly enhanced the safety and success rates of these procedures, making them accessible even to pediatric patients—who represent a large proportion of moyamoya cases.
Conclusion: Choosing the Right Treatment Path
While stenting may seem like a minimally invasive shortcut, it poses serious risks and offers limited benefits for moyamoya patients. In contrast, bypass surgery addresses the root cause of compromised blood flow and provides durable protection against neurological decline. Patients diagnosed with moyamoya should seek care from specialized neurovascular centers with multidisciplinary teams experienced in cerebrovascular reconstruction to ensure optimal outcomes.