Salvage stereotactic radiosurgery following primary microsurgical resection for vestibular schwannomas: A systematic review & meta-analysis

Stereotactic radiosurgery (SRS) is a commonly utilized modality for the treatment of vestibular schwannomas (VS), either as upfront treatment or after initial microsurgery. The aim of this study was to assess outcomes in patients with VSs who underwent salvage SRS for tumor progression or residual tumor following primary microsurgical resection. The MEDLINE/PubMed database was queried from inception to November 2024. The primary outcomes of interest were the VS-related reoperation and repeat SRS following salvage SRS. The secondary outcomes were radiological tumor control rates, post-SRS facial nerve function, and new or worsened clinical symptoms. Eleven studies were eligible for this review, containing 553 patients who underwent salvage SRS following initial microsurgical resection. During the follow-up period, 5.2% (95%CI 3.4–7.8) and 3.2% (95%CI 1.9–5.6) of all patients who underwent salvage SRS required repeat microsurgery and SRS, respectively. Radiological tumor control was 87.5% (95%CI 76.6–93.7), with volumetric reduction recorded at 65.6% (95%CI 50.4–78.2). Facial nerve function worsened in 7.8% (95%CI 4.7–12.7) of patients, and 5.6% (95%CI 3.4–9) developed new or worsened trigeminal neuropathy. 3.3% (95%CI 1.4–7.7) and 3.4% (95%CI 1.8–6.3) of patients reported new or worsening tinnitus and vertigo, respectively. This study shows that salvage SRS for treating VS after failed microsurgery yielded favorable tumor control with reasonable complication rates, including low rates of cranial nerve deterioration. SRS proved to be a viable salvage treatment option for VS in case of tumor recurrence or progression after initial microsurgery, particularly for patients who are not candidates for repeat surgery or prefer a less invasive approach. These results may inform patient counseling and clinical decision-making following failed microsurgical resection of VS.