OBJECTIVE The goal of this retrospective cohort study was to assess long-term outcomes in patients with vestibular schwannoma (VS) who underwent stereotactic radiosurgery (SRS) after initial microsurgical resection. METHODS From the authors' database of 1770 patients with VS, the authors retrospectively analyzed data from 173 Gamma Knife SRS procedures for VS after 1 (128 procedures) or multiple (45 procedures) microsurgical resections. The median length of the interval between the last resection and SRS was 42 months (range 2-329 months). The median length of clinical follow-up was 74 months (range 6-285 months). Progression-free survival after SRS was determined with Kaplan-Meier analysis. RESULTS At the time of SRS, the hearing of 161 patients (93%) was Gardner-Robertson Class V, and 81 patients (47%) had facial neuropathy (i.e., facial function with House-Brackmann [HB] grades of III-VI), 87 (50%) had trigeminal neuropathy, and 71 (41%) reported imbalance or disequilibrium disorders. The median tumor volume was 2.7 cm3 (range 0.2-21.6 cm3), and the median dose to the tumor margin was 13 Gy (range 11-20 Gy). Radiosurgery controlled growth of 163 (94%) tumors. Progression-free survival after SRS was 97% at 3 years, 95% at 5 years, and 90% at 10 years. Four patients with delayed tumor progression underwent repeat SRS at a median of 35 months (range 23-64 months) after the first SRS. Four patients (2.3%) with tumor progression underwent repeat resection at a median of 25 months (range 19-33 months). Among the patients with any facial dysfunction (indicated by HB grades of II-VI), 19% had improvement in this condition after SRS, and 5.5% with some facial function (indicated by HB grades of I-V) developed more facial weakness. Among patients with trigeminal neuropathy, 20% had improvement in this condition, and 5.8% developed or had worsened trigeminal neuropathy after SRS. CONCLUSIONS Stereotactic radiosurgery offered a safe and effective long-term management strategy for VS patients whose tumors remained or recurred after initial microsurgery.
Keywords: G-R = Gardner-Robertson; GK = Gamma Knife; Gamma Knife; HB = House-Brackmann; QOL = quality of life; SRS = stereotactic radiosurgery; VS = vestibular schwannoma; microsurgery; recurrence; stereotactic radiosurgery; vestibular schwannoma.