Prognostic Factors of Hearing Preservation after Vestibular Schwannoma Surgery

Objectives: To validate the prognostic capacity of several pre- and intraoperative parameters of hearing preservation after vestibular schwannoma surgery. Study Design: A retrospective study of a consecutive series of 29 patients treated with the enlarged middle cranial fossa approach. Quantitative parameters were tumor volume, linear tumor size, pure-tone and speech audiometry, PTA, SDS, SRT, ABR (IPL I-V, Δ JV), and the caloric test (speed and frequency). Qualitative parameters were fundus involvement by the tumor (in MRI and surgical record), nerve of tumor origin (in MRI and surgical record), ABR parameters (well-shaped ABRs: waves I, III, and V present; presence of wave V). Methods: All patients were divided in two groups on the basis of postoperative hearing: preserved hearing (55%) and nonpreserved hearing (45%). The Kolmogorov-Smirnov test was used to evaluate normality of distribution for continuous data. The t-test was applied for normally distributed continuous data, and the Mann-Whitney test for non-normally distributed continuous data. The chi-square test was used for comparisons of categorical data. Results: Tumor volume was found to be the only statistically significant prognostic parameter for hearing preservation (p = 0.007). None of other parameters reached statistical significance. Conclusions: Tumor size is a predictive factor for hearing preservation after vestibular schwannoma surgery, and patients with smaller tumors, based on volume measurement, have significantly better chances for retaining hearing. This has an impact on decision-making and timing of surgery.