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Objective: Hearing restoration has always been a dream in vestibular schwannoma (VS) surgery. The aim of this study is to describe an endoscopic assisted transcanal retrocochlear approach to the internal auditory canal (IAC) with total removal of the VS; simultaneously we assessed the anatomical and functional aspects of hearing restoration with cochlear implant (CI)., Study Design: A retrospective case series., Setting: Tertiary referral center., Patients: Six patients affected by VS involving the fundus of the IAC (Koos stage I-II) were included in this study. The patients already demonstrated symptoms of IAC involvement by the neuroma, with severe to profound hearing loss., Interventions: Transcanal microscopic, endoscopic assisted, approach was chosen for total tumor removal. Preoperative and intraoperative electrophysiological monitoring was performed using electrically evoked auditory brainstem responses (EABR) to evaluate preservation of cochlear function., Main Outcome and Measures: A retrospective evaluation of electrophysiological data collected during surgeries has been conducted; clinical outcomes, surgical complications, and postoperative radiological evaluations were also considered., Results: Total tumor removal was achieved in all patients with no major complications. One patient showed temporary facial palsy (HB stage II). We were able to preserve cochlear function in five out of six patients. In those patients intraoperative monitoring with EABR was performed after tumor removal with good responses., Conclusions: Transcanal retrocochlear approach for VS removal allows preservation of cochlea and cochlear nerve function. This is the first step towards developing an effective surgical technique for VS removal and hearing rehabilitation with CI.

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.

Hypothesis: Electrical stimulation of the inferior colliculus in the midbrain can provide a safe and efficacious alternative to auditory brainstem implants (ABIs)., Background: Patients with neurofibromatosis type 2 (NF2) receive limited speech recognition with ABIs. Some ABI patients without NF2 can achieve excellent speech understanding, suggesting that the limited NF2 performance is due to brainstem damage from the tumor and its removal., Methods: An array of electrodes (Med-El ABI) was placed on the dorsal surface of the inferior colliculus in the midbrain of a human volunteer as an auditory prosthesis via an infratentorial supracerebellar median surgical approach. Electrophysiological responses, psychophysical responses, and speech recognition were measured., Results: Electrical stimulation produced auditory sensations on all 12 electrodes with no nonauditory sensations. Auditory threshold levels indicated the stability of the electrode array over time. Electrophysiological measures showed activation in the contralateral auditory cortex but none in ipsilateral cortex. All electrodes demonstrated a full range of loudness sensation and electrode-specific pitch sensations. Speech recognition was significant, but limited in the first month after surgery., Conclusion: This approach may provide advantages for patients with brainstem damage.