Copyright © 2017 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited. Transcanal Transpromontorial Acoustic Neuroma Surgery: Results and Facial Nerve Outcomes  Daniele Marchioni,  Davide Soloperto, yBarbara Masotto,  Cristoforo Fabbris,  Stefano De Rossi, zDomenico Villari, and zLivio Presutti  Otolaryngology Department; yNeurosurgery Department, University Hospital of Verona, Verona; and zOtolaryngology Department, University Hospital of Modena, Modena, Italy Background: Recently, the transcanal approach for the removal of acoustic neuromas has been introduced. Facial nerve (FN) preservation is one of the main challenges of this kind of surgery. Objective: To describe our experience in the surgical treatment of acoustic neuromas, focusing on the functional results of FN preservation after a transcanal approach. Methods: A retrospective chart review was carried out on clinical data and videos from operations on 49 patients who underwent surgery with a totally transcanal exclusive endo- scopic approach for Koos stage I–II lesions, or an enlarged transcanal transpromontorial approach for Koos stage II–III tumors, between March 2012 and February 2017. Patients and tumor characteristics, clinical manifestations, radiologic features, audiological results, FN outcomes (according to the House–Brackmann [HB] grading system) and complications were evaluated. Tumors were classified according to the Koos grading system. Results: The age of the patients (34 females and 15 males) ranged from 27 to 77 years (mean age: 54.9 yr). Preoperative diagnosis was ‘‘vestibular schwannoma’’ in all patients. At the last follow-up (range 1–60 mo, mean 13.9 mo), 42 of 49 showed grade I HB FN function, 5 of 49 grade II HB, and 2 of 49 grade III HB. Overall, in 95.9%, FN function was preserved (grade I–II HB) with stable results at follow-up; in 4.1% of cases, FN function was reduced, but not worse than grade III. Conclusion: The transcanal approach represents a feasible, minimally invasive, and conservative technique for the management of acoustic neuromas of the internal auditory canal. Key Words: Acoustic neuromas—Endoscopic approach—Facial nerve outcomes—Inner ear—Microscopic surgery. Otol Neurotol 38:xxx–xxx, 2017. The aim of acoustic neuroma (AN) surgery is to eradi- cate the tumor, preserving facial nerve (FN) function as much as possible, using sufficient exposure to minimize surgical morbidity (1). The retrosigmoid, middle cranial fossa and translabyrinthine approaches are the most com- monly used and well-documented approaches in AN surgery (2–5). No matter which approach is used, surgery for AN is traditionally considered to be very delicate. Postoperative morbidity can be high, for example, from intraoperative and postoperative complications. In recent years, the introduction of endoscopic ear surgery has led to improved anatomical knowledge from the external to internal auditory canal (IAC). This knowledge has allowed the development of transcanal transpromontorial surgery (6) using the external auditory canal as a natural corridor to remove ANs involving the IAC with or without minimal extension to the cerebellopontine angle (CPA). Using this approach, the aim was to identify an alterna- tive surgical technique for the management of ANs limited to the IAC, minimizing intraoperative and postoperative complications. The first study was carried out on 10 patients affected by AN (7). From this encouraging experience, we started to use this technique increasingly, enlarging the surgical window to the CPA, and extending the indications for ANs of Koos stage II–III (8). The present study reports the complete case series of all the patients who have been treated so far using these techniques for AN removal (Koos stages I–III), in particular focusing on the FN outcome, and postoperative complications. METHODS A retrospective chart review was carried out on patients who underwent transcanal transpromontorial surgery for ANs at the Address correspondence and reprint requests to Cristoforo Fabbris, M.D., Otolaryngology Department, University Hospital of Verona, Piazzale Aristide Stefani 1, 37126 Verona, Italy; E-mail: cristoforo. fabbris@student.unife.it Author contributions: Conception and design: D.M., L.P. Acquisition of data: D.M., C.F., S.D.R., B.M., D.V. Analysis and interpretation of data: D.S., D.M. Drafting the article: D.S., D.M., C.F. Critically revising the article: D.M. Reviewed submitted version of manuscript: C.F. Approved the final version of the manuscript on behalf of all authors: C.F. Administrative/technical/material support: C.F., S.D.R., D.S., D.M. Study supervision: D.M. The authors disclose no conflicts of interest. DOI: 10.1097/MAO.0000000000001658 1 Otology & Neurotology xx:xx–xx ß 2017, Otology & Neurotology, Inc.