Hearing preservation in vestibular schwannoma with retrosigmoid approach: updating retrolabyrinthine meatotomy.

PURPOSE: Report the updated version of retrolabyrinthine meatotomy (RLM) to the whole internal auditory canal in hearing preservation surgery (HPS) via retrosigmoid approach (RS) in sporadic vestibular schwannoma (VS). METHODS: Description of surgical technique of VS removal with microscopic RS approach and RLM. Fifty-six consecutive patients with intrameatal or small (up to 15 mm extrameatal size) sporadic VS, with fundus free or fundus involved by the tumor, and good hearing at diagnosis, who underwent HPS, were retrospectively reviewed. Elective (protocol) indication for HPS was ≤ 10 mm size, ≤ 30 PTA, and ≥ 70 SDS. RESULTS: Complete VS removal was achieved in all 56 cases, with no residual tumor or recurrence. The overall hearing preservation rate was 64% (36/56 patients), and 66% (28/42 patients) in protocol cases. Hearing outcome in fundus free vs. fundus involved cases did not show significant difference. At one-year postoperative follow-up, facial nerve function was House-Brackmann (HB) grade 1 or 2 in 54/56 patients (96%) and grade 3 in 2/56 patients (4%). The rate of relevant complications was 11% (6/56), with nasal CSF leak being the most frequent; no permanent sequelae occurred. CONCLUSIONS: Microscopic RLM with three-dimensional view is a convenient option to expose the internal auditory canal up to the fundus and to remove VS irrespective of fundus involvement.