2026 Proffered Presentations
S130: ELECTRICALLY EVOKED AUDITORY BRAINSTEM RESPONSE AS A PREDICTOR OF LONG-TERM HEARING OUTCOMES FOLLOWING TRANSLABYRINTHINE VESTIBULAR SCHWANNOMA RESECTION WITH COCHLEAR IMPLANTATION
Claire E Perrin, BS1; Alena M Pauley, MS1; Benjamin T Ostrander, MD, MSE2; Jonathan Dilgen, PhD, CNIM3; Peter R Dixon, MD4; Marc S Schwartz, MD5; Rick A Friedman, MD, PhD6; Douglas M Bennion, MD, PhD7; 1University of California, San Diego School of Medicine, La Jolla, California, United States; 2Department of Otolaryngology - Head and Neck Surgery, University of Minnesota, Minneapolis, Minnesota, United States; 3University of California, San Diego Health, La Jolla, California, United States; 4Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States; 5Department of Neurosurgery, University of California, San Diego, La Jolla, California, United States; 6Department of Otolaryngology - Head and Neck Surgery, Department of Surgery, University of California, San Diego, La Jolla, California, United States; 7Department of Otolaryngology - Head and Neck Surgery, University of Iowa, Iowa City, Iowa, United States
Hypothesis/Objective: Intraoperative monitoring of acoustically evoked auditory brainstem response (ABR) waveforms is used to assess auditory function during vestibular schwannoma (VS) resection. However, in some patients, particularly those undergoing a translabyrinthine approach, acoustic ABR cannot be reliably obtained. Electrically evoked ABR (eABR) offers an alternative method for monitoring cochlear nerve integrity and may help predict postoperative auditory outcomes in patients receiving concurrent cochlear implantation following translabyrinthine VS removal. However, the clinical utility of intraoperative eABR is not well defined. This study evaluates eABR as a tool for assessing cochlear nerve integrity and forecasting auditory results after translabyrinthine resection with concurrent cochlear implantation. We hypothesized that patients who had an eABR response to stimulation of the cochlear nerve at the internal auditory canal (IAC) would have improved cochlear implant outcomes compared to those who did not.
Methods: Nine patients undergoing microsurgical VS resection were prospectively enrolled. At the completion of tumor dissection, a bipolar stimulating electrode was applied to the cochlear nerve at the porus acusticus of the IAC to obtain eABR recordings. An eABR response was defined as a repeatable waveform of any amplitude across three trials at the same latency. Patients with an eABR response to stimulation of the cochlear nerve at the IAC porus (“responders”) were compared to those without a response. eABR outcomes were correlated with auditory outcomes collected at cochlear implant activation and longitudinally over a 1-year post-operative period, including patient-reported Cochlear Implant Quality of Life (CIQOL) scores. Mann-Whitney U tests were used to correlate eABR outcomes with continuous measures, while Fisher’s exact tests were used for categorical measures. Point-biserial correlation was used to assess the relationship between CIQOL and eABR scores.
Results: At the time of analysis, 9 participants with complete data were included (mean linear tumor dimension 11.3mm, range 3-20 mm). All patients with IAC eABR responses (3/3) demonstrated sound awareness at CI activation, compared to only half without eABR responses (3/6), however, this relationship did not reach statistical significance (p=0.46). Responders achieved higher open-set CNC scores, including median word recognition score of 43% versus 25% among non-responders (p=0.359), and phoneme recognition of 44% compared with 0% (p=0.107). The first four participants to complete one-year follow-up demonstrated differences in CIQOL-10 global scores, with responders scoring 44 and 38, and non-responders scoring 38 and 35. A strong correlation was observed between the presence of a distal/IAC eABR response and CIQOL-10 scores (point biserial r=0.69), though this did not reach statistical significance (p = 0.35), likely due to the small sample size.
Conclusion: Intraoperative eABR may uniquely allow for timely interrogation of cochlear nerve integrity and serve as a predictive mechanism for auditory outcomes in patients undergoing cochlear implantation concurrent with microsurgical resection for VS. Presence of eABR responses in response to auditory nerve stimulation at the IAC is a promising electrophysiologic marker of postoperative cochlear implant speech perception ability. The addition of one-year CIQOL data provides evidence linking intraoperative electrophysiologic findings to longer-term patient-reported quality-of-life improvements, extending prior preliminary observations.