Salvage microsurgery for vestibular schwannoma after failed stereotactic radiosurgery: a multi-institutional retrospective study

Objective The management of sporadic vestibular schwannoma (VS) with stereotactic radiosurgery (SRS) is becoming increasingly common worldwide. Despite its efficacy, treatment failure can occur in a subset of patients. This study aimed to describe the clinical outcomes of salvage microsurgery following failed primary SRS in patients with sporadic VS. Methods This retrospective study included adult patients (>= 18 years) who underwent salvage microsurgery following failed primary SRS at six European tertiary referral centers. Data collection was performed from January 2012 to December 2022, and data analysis was performed from July to September 2025. Results Among 28 patients (15 men, 13 women), surgery indication was radiological regrowth in 27/28 patients. The median interval from SRS to salvage microsurgery was 48 months (range, 24-120), and the median age at time of salvage microsurgery was 53 years (range, 30-74). Axial diameter increased from median 18.5 mm (range, 7.5-27) before SRS to 25 mm (range, 10.5-33) before surgery. Gross total resection was achieved in 13/28 (46.4%). Complications occurred in 3/28 patients (10.7%). Serviceable hearing (AAO-HNS class A/B) declined from 10/20 patients (50.0%) pre-SRS to 4/24 (16.7%) preoperatively; all patients with postoperative follow-up (14/28) were AAO-HNS class D. Preoperative facial nerve function was House-Brackmann (HB) grade I in 25/28 patients (89.3%); good facial function (HB I-II) was seen in 14/27 (51.9%) at discharge and 11/15 (73.3%) at 12 months, with 3/15 (20.0%) remaining HB grade V-VI. Conclusion Salvage microsurgery is a viable therapeutic option for managing VS after failed SRS. GTR or NTR with a relatively low complication profile is achievable, although hearing preservation is not a realistic goal in this setting, whereas facial nerve function may improve postoperatively.