Intraoperative Compound Action Potentials as a Predictor of Postoperative Cortical Auditory Evoked Potentials in Cochlear Implant Users.

Abstract

Introduction: Electrically evoked cortical auditory evoked potentials (ECAEPs) are central brain responses to auditory stimuli that correlate with postoperative cochlear implant (CI) hearing outcomes. They differ from electrically evoked compound action potentials (ECAPs) which are peripheral responses that can be elicited intraoperatively and may also predict CI hearing outcomes. It is not known to what degree ECAP and ECAEP responses are associated with each other. Such a correlation, if present, may allow for an earlier and more accurate prediction of postoperative hearing outcomes.

Methods: This retrospective study involved 42 adult CI users. Threshold levels and amplitude growth function slopes of intraoperative ECAPs were compared to the latencies and peak-to-peak amplitudes of postoperative ECAEP responses at three different cochlear electrode array sites (apical, medial, and basal).

Results: A weak positive relationship was found between intraoperative ECAP thresholds and ECAEP N1-P2 peak-to-peak amplitude (r = 0.301, p = 0.005). Time between ECAP and ECAEP measurements was weakly correlated with P1-N1 peak-to-peak amplitude (r = 0.321, p = 0.002) and ECAEP N1-P2 peak-to-peak amplitude (r = 0.340, p = 0.001). ECAP amplitude growth function slopes varied by electrode location (χ2 = 26.701, df = 2, p = 0. 000002).

Conclusion: These results suggest that intraoperative ECAP responses do not robustly predict postoperative ECAEP responses, providing caution against the use of ECAPs as a predictive tool for CI hearing outcomes.