Moyamoya Disease Surgery: Understanding the Risks and Potential Complications

Overview of Moyamoya Surgery and Its Associated Risks

Moyamoya disease is a rare cerebrovascular disorder that often requires surgical intervention to restore proper blood flow to the brain. While revascularization surgery—such as direct or indirect bypass procedures—can significantly improve outcomes, it is considered one of the more complex and high-risk neurosurgical procedures. Even when the operation proceeds smoothly, patients may still face serious postoperative complications due to the delicate nature of cerebral circulation in moyamoya patients.

Understanding Cerebral Hyperperfusion Syndrome

One of the most critical risks following surgery is cerebral hyperperfusion syndrome. In moyamoya disease, the brain often adapts to chronically reduced blood flow by developing collateral vessels that maintain a fragile equilibrium. When surgeons introduce new blood supply through bypass grafting, this sudden increase in perfusion can overwhelm the brain's autoregulatory mechanisms. The result? A dangerous surge in intracranial blood flow that may lead to hemorrhagic stroke, severe headaches, seizures, or even permanent neurological damage.

Increased Risk of Hemorrhage and Ischemic Events

While the goal of surgery is to prevent future strokes, paradoxically, the procedure itself carries a risk of triggering both hemorrhagic and ischemic events. After revascularization, the redistribution of cerebral blood flow can destabilize previously compensated areas. This shift may cause ischemia in regions that were relying on limited but stable circulation, potentially leading to postoperative infarcts—either near the surgical site or in remote but vulnerable brain areas.

Challenges with Graft Patency and Long-Term Efficacy

Another concern is the long-term success of the vascular bypass. Even if blood flow is successfully established during surgery, small vessel occlusion can occur weeks or months later, diminishing the intended benefits. Factors such as endothelial dysfunction, thrombosis, or inadequate collateral development can compromise graft patency, resulting in suboptimal clinical outcomes. Regular imaging follow-ups, including MRI and angiography, are essential to monitor graft function and detect early signs of failure.

Common Postoperative Complications

Beyond hyperperfusion and graft issues, patients may experience transient neurological deficits, seizures, or cognitive changes after surgery. These complications underscore the importance of careful patient selection, meticulous surgical technique, and comprehensive postoperative management. Multidisciplinary care involving neurosurgeons, neurologists, and rehabilitation specialists plays a vital role in minimizing risks and optimizing recovery.

Conclusion: Weighing Benefits Against Surgical Risks

While moyamoya surgery presents notable risks—including hyperperfusion, stroke, and graft failure—the potential benefits in terms of stroke prevention and improved quality of life often justify the intervention. Advances in microsurgical techniques, intraoperative monitoring, and postoperative care continue to enhance safety and outcomes. Patients should engage in thorough discussions with their medical team to fully understand individual risk factors and make informed decisions about treatment.