Long-Term Vestibulaorcochlear Function and Vestibular Compensation after Microsurgical Resection of Vestibular Schwannoma via the Retrosigmid Approach

Abstract

Objective: To evaluate long-term vestibulocochlear function of patients (P) who were operated on vestibular schwannoma via retrosigmoid approach. Methods: A total of 64 P were enrolled in this study. A questionnaire was applied to evaluate current vestibulocochlear complaints comparing with the preoperative status. Cochlear function was assessed by audiometry, vestibular function (VF) by video-oculography (VOG), and central compensation (CC) by rotational chair testing. Results: Mean follow-up was 77 months, mean tumor size was 22.4 mm. As compared to preoperative status, rate of tinnitus (61%) did not change at follow-up. Vertigo improved significantly (pre. vs. post: 40-28%). Balance disturbances (BD) increased slightly (50-58%). In the audiometry, postoperative useful hearing (UH) rate of 52% could be estimated. VOG showed that 80% had lost VF, 16% had hypofunction, and 4% normal VF. Overall 84% showed CC. P without CC at follow-up complained significantly more frequently of BD than those with CC, p = 0.035. Risk of developing postoperative non-UH increased with initial tumor size by a factor of 2.2 every 10 mm, p = 0.020. P age raised risk of developing postoperative non-UH by a factor of 1.7 every 10 years, p = 0.039. A better preoperative hearing function increased the chance of keeping postoperative UH significantly p = 0.002. Conclusions: Young P with small tumors and good preoperative hearing seem to have better chances of preserving UH. Developing CC is not obligatory but a process, which might fail leading more frequently to BD.