Objective:Targeted surgical precision and minimally invasive techniques are of the utmost importance when it comes to resection of cavernous malformations involving the brainstem region. Minimization of the surgical corridor is desirable but should not compromise the extent of resection. This study provides detailed information on the role of endoscopic techniques in this challenging surgical task.Methods:A retrospective analysis of medical documentation, radiologic studies and detailed

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... rative video-documentation was performed for all consecutive patients, who underwent surgical resection of brainstem cavernous malformations between 2010 and 2020 at the authors' institution. A case-based volumetry of the corticotomy was performed in relation to the cavernoma's dimension. Results:A total of 20 procedures have been performed in 19 patients. Neuroendoscopy was implemented in all cases. Mean size of the lesion 5.4 (±5)mm3. Average size of the brainstem corticotomy was 4.5x3.7 (±1.0x1.1)mm with a median relation to the cavernoma's dimension of 9.99% (1.2%-31.39%). Endoscopic 360° inspection of the resection cavity was feasible in all cases. There were no endoscopy related complications. Mean follow up was 27.8 (12-89) months. Gross-total resection was achieved in all but one cases (95%). Sixteen procedures (80%) resulted in an improved or stable medical condition. Eleven patients (61.1%) showed further improvement 12 months after initial surgery. Conclusion:Experience provided, endoscopic techniques can be safely implemented in surgery for BSCM. Combination of neuroendoscopic visualization and neuronavigation might enable a targeted size of brainstem corticotomy. Endoscopy can be considered as a valuable additive tool to ensure gross total resection of BSCM.