Transcanal Transpromontorial Acoustic Neuroma Surgery: Results and Facial Nerve Outcomes.

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 endoscopic 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.