Chronological characterization of hearing preservation after radiosurgery for vestibular schwannoma: a comprehensive meta-analysis

OBJECTIVE Hearing outcomes following Gamma Knife radiosurgery (GKRS) for vestibular schwannoma (VS) are multifactorial and poorly characterized in prior literature. In this study the authors evaluated hearing outcomes chronologically to identify prognostic factors of serviceable hearing preservation (HP) rates following GKRS for VS. METHODS Six medical databases were queried according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies reported VS treated with single-fraction GKRS and included the HP rate following GKRS. HP was defined as a postoperative Gardner-Robertson score ≤ 2 among patients with preoperative serviceable hearing. A meta-analysis with random-effects modeling was performed for variables of interest. RESULTS Data from 42 articles with a total of 6582 patients were analyzed; the average age of patients was 54 years and the average follow-up time was 68 months. The pooled proportion of preoperative serviceable hearing was 76%, and the pooled HP rate was 60% at the last follow-up visit. At < 5 years after GKRS, age was significantly correlated with HP on both continuous and categorical analyses (p = 0.001 and p = 0.011, respectively). Between 5 and < 10 years of follow-up, HP was associated with a radiation dose of 12.5 Gy, but not with age or tumor volume. At ≥ 10 years after radiosurgery, a significant negative correlation was seen between marginal radiation dose and HP on both continuous and categorical analyses (p = 0.001 and p = 0.021, respectively). CONCLUSIONS This meta-analysis identifies age and radiation dose as independent prognostic factors for HP. Age-related hearing deterioration appears to be concentrated in the first 5 years after GKRS, whereas radiation dose was associated with HP at last follow-up, between 5 and < 10 years, and at ≥ 10 years after radiosurgery. This meta-analysis offers an objective overview of the literature and a framework for clinical decision-making, with applications for treatment planning and patient counseling.