On Entering the Fortress: Surgical Approaches to Brainstem Lesions

Objective: To evaluate the effectiveness and safety of modern microsurgical and endoscopic approaches for the management of brainstem lesions, a region often described as the “fortress” of the central nervous system due to its complex anatomy and critical functional pathways. Methods: We conducted a retrospective analysis of patients who underwent surgical treatment for intrinsic and extrinsic brainstem lesions at our institution. Approaches included retrosigmoid, suboccipital, and transpetrosal craniotomies, as well as minimally invasive keyhole and endoscopic-assisted techniques. Patient demographics, lesion type, chosen approach, extent of resection, intraoperative neuromonitoring data, and postoperative functional outcomes were assessed. Results: Gross-total or near-total resection was achieved in the majority of cases, with preservation of critical neurological functions in most patients. The use of safe entry zones, combined with real-time neuromonitoring and neuronavigation, proved essential in minimizing morbidity. Endoscopic assistance enhanced visualization within deep surgical corridors, particularly in ventral and midline lesions, reducing retraction-related injury. Postoperative improvement or stability was observed in a substantial proportion of patients, with complication rates comparable to established literature. Transient new deficits were documented but resolved in most cases within follow-up, while permanent morbidity remained limited. Conclusion: Surgical access to brainstem lesions requires precise anatomical knowledge, careful patient selection, and the integration of advanced microsurgical and endoscopic techniques. When performed with attention to safe entry zones and supported by modern adjuncts, these approaches allow effective resection with acceptable risk. Entering this “fortress” remains among the greatest challenges in neurosurgery, but evolving strategies continue to improve outcomes for patients with these formidable lesions. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany