Retrolabyrinthine Meatotomy as Part of Retrosigmoid Approach to Expose the Whole Internal Auditory Canal: Rationale, Technique, and Outcome in Hearing Preservation Surgery for Vestibular Schwannoma

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>BACKGROUND</jats:title> <jats:p>Vestibular schwannoma extending to the fundus of the internal auditory canal is currently considered an unfavorable condition for hearing preservation surgery via a retrosigmoid approach because the lateral end of the canal is hard to view directly during microsurgery.</jats:p> </jats:sec> <jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>To present an improved retrolabyrinthine meatotomy (RLM) technique that enables the full length of the cochlear and facial nerves to be inspected up to their orifices on the fundus. Long-term results are briefly reported.</jats:p> </jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>A consecutive series of 100 cases with various degrees of fundus involvement underwent surgery via a retrosigmoid approach and RLM. The follow-up ranged from 4 to 14 yr. Outcomes on hearing and facial nerve function were recorded, and preoperative MRI findings of the tumor on the fundus were correlated with the surgical findings and the long-term radicality of the tumor resection.</jats:p> </jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>Residual tumor on the fundus was identified in 3 cases, all belonging to the group with tumors adhering to the fundus. The functional results were in line with the best reported outcomes of this surgery.</jats:p> </jats:sec> <jats:sec> <jats:title>CONCLUSION</jats:title> <jats:p>RLM via a retrosigmoid approach seemed adequate for the purposes of hearing preservation surgery and enabled the full course of the facial and cochlear nerves through the internal auditory canal to be exposed to direct view. Tumors adhering to the vestibular quadrant of the fundus were more difficult to remove, and there were a few cases of local residual tumor.</jats:p> </jats:sec>