Transcanal Transpromontorial Approaches to the Internal Auditory Canal: A Systematic Review

Abstract

ObjectiveExclusive endoscopic (EETTA) and expanded (ExpTTA) transcanal transpromontorial approaches have shown promising results for treating internal auditory canal (IAC) lesions. We reviewed the literature to answer the question: “Do EETTA and ExpTTA achieve high rates of complete resection and low rates of complications in treating patients with IAC pathologies?”Data SourcesPubMed, EMBASE, Scopus, Web of Science, and Cochrane were searched.Review MethodsStudies reporting EETTA/ExpTTA for IAC pathologies were included. Indications and techniques were discussed and meta‐analyzed rates of outcomes and complications were obtained with random‐effect model meta‐analyses.ResultsWe included 16 studies comprising 173 patients, all with non‐serviceable hearing. Baseline FN function was mostly House‐Brackmann‐I (96.5%; 95% CI: 94.9–98.1%). Most lesions were vestibular/cochlear schwannomas (98.3%; 95% CI: 96.7–99.8%) of Koos‐I (45.9%; 95% CI: 41.3–50.3%) or II (47.1%; 95% CI: 43–51.1%). EETTA was performed in 101 patients (58.4%; 95% CI: 52.4–64.3%) and ExpTTA in 72 (41.6%; 95% CI: 35.6–47.6%), achieving gross‐total resection in all cases. Transient complications occurred in 30 patients (17.3%; 95% CI: 13.9–20.5%), with meta‐analyzed rates of 9% (95% CI: 4–15%), comprising FN palsy with spontaneous resolution (10.4%; 95% CI: 7.7–13.1%). Persistent complications occurred in 34 patients (19.6%; 95% CI: 17.1–22.2%), with meta‐analyzed rates of 12% (95% CI: 7–19%), comprising persistent FN palsy in 22 patients (12.7%; 95% CI: 10.2–15.2%). Mean follow‐up was 16 months (range, 1–69; 95% CI: 14.7–17.4). Post‐surgery FN function was stable in 131 patients (75.8%; 95% CI: 72.1–79.5%), worsened in 38 (21.9%; 95% CI: 18.8–25%), and improved in 4 (2.3%; 95% CI: 0.7–3.9%), with meta‐analyzed rates of improved/stable response of 84% (95% CI: 76–90%).ConclusionTranspromontorial approaches offer newer routes for IAC surgery, but their restricted indications and unfavorable FN outcomes currently limit their use. Laryngoscope, 2023

A Case Report Demonstrating Preservation of Vestibular Receptor Function after Transcochlear Removal of an Intracochlear Schwannoma with Extension to the Fundus of the Internal Auditory Canal

“…The three most common microsurgical approaches used to remove vestibular schwannomas of the internal auditory canal (IAC) and/or the cerebello-pontine angle (CPA) are the translabyrinthine and the retrosigmoid approaches, that can be used even for the resection of large tumors, and the middle fossa approach for smaller tumors in the IAC and only limited extension to the CPA [ 1 ]. Further approaches are the retrolabyrinthine approach, which is especially suited for medially located tumors [ 2 ], and the more recently suggested exclusively endoscopic and expanded transcanal transpromontorial or transcanal infrapromontorial approaches for vestibular schwannoma [ 3 , 4 , 5 ]. The retrosigmoid, the middle fossa, and the retrolabyrinthine approaches offer the possibility of hearing preservation, while destruction of the inner ear structures in the other approaches inherently sacrifices hearing function with anecdotal exceptions [ 6 , 7 ].…”