Facial Nerve Outcomes and Extent of Resection in Salvage Microsurgery After Failed Stereotactic Irradiation for Vestibular Schwannoma: A Single-Center Series

Background/Objectives: This study aimed to describe facial nerve (FN) outcomes, extent of resection, and dissection characteristics after salvage microsurgery for vestibular schwannoma (VS) progression following stereotactic irradiation. Methods: Eighteen patients were retrospectively reviewed. Group 1 (n = 12) had received irradiation alone; Group 2 (n = 6) had undergone microsurgery and irradiation. FN function was graded using the House–Brackmann (HB) system before salvage, within 24 h postoperatively, and at final follow-up. Two independent reviewers assessed dissection conditions using a study-specific, nonvalidated score. Analyses were primarily descriptive. Results: Gross total resection was achieved in 9/12 patients (75%) in Group 1 and 3/6 (50%) in Group 2. Pre-salvage HB I–II function was present in 12/12 and 2/6 patients, respectively, and these proportions were unchanged at final follow-up. However, three Group 1 patients (25%) and two Group 2 patients (33.3%) deteriorated relative to baseline. Dissection conditions were classified as favorable in 10/12 Group 1 patients and in none of the six Group 2 patients. Median postoperative follow-up was 51.5 months in Group 1 and 67.0 months in Group 2. Exploratory radiation-modality comparisons were inconclusive. Tinnitus and vertigo findings were based on nonstandardized clinical documentation. Conclusions: Final HB I–II function was observed in all 12 patients treated with irradiation alone before salvage surgery, although three deteriorated relative to their pre-salvage grade. Findings after previous microsurgery and irradiation require cautious interpretation because of baseline differences and the small sample. These observations do not establish the superiority of a treatment pathway or an independent prognostic effect of dissection conditions.