A Rare Case of Bilateral Lateral Ventricular Subependymomas With Complete Resection of the Residual Tumor via Flexible Neuroendoscopy 20 Years After Initial Surgery.

Subependymoma is a benign, slow-growing tumor that arises from the ventricular wall. Although often asymptomatic, it can obstruct cerebrospinal fluid flow, leading to hydrocephalus. Most subependymomas are unilateral, typically located in the fourth ventricle, followed by the lateral ventricles. Bilateral involvement of the lateral ventricles is extremely rare. We report the case of a 62-year-old man with bilateral subependymomas located in the anterior horns of both lateral ventricles, who presented with impaired consciousness due to epilepsy. Nineteen years earlier, the tumor in the anterior horn of the left lateral ventricle had been resected via craniotomy with frontal lobe uncapping. The lesion in the right lateral ventricle, initially small, gradually enlarged over two decades and was subsequently resected using flexible neuroendoscopy. This approach allowed safe and effective tumor removal within a spacious intraventricular working environment while maintaining minimal invasiveness. In cases involving relatively small and hypovascular intraventricular tumors, flexible neuroendoscopy represents a viable minimally invasive surgical option. Continued technological advancements are anticipated to further enhance the safety and applicability of neuroendoscopic tumor resections.