Round Window Electrocochleography Before and after Cochlear Implant Electrode Insertion

Objective/HypothesisPrevious reports have documented the feasibility of utilizing electrocochleographic (ECoG) responses to acoustic signals to assess trauma caused during cochlear implantation. The hypothesis is that intraoperative round window ECoG before and after electrode insertion will help predict postoperative hearing preservation outcomes in cochlear implant recipients.Study DesignProspective cohort study.MethodsIntraoperative round window ECoG responses were collected from 31 cochlear implant recipients (14 children and 17 adults) immediately prior to and just after electrode insertion. Hearing preservation was determined by postoperative changes in behavioral thresholds.ResultsOn average, the postinsertion response was smaller than the preinsertion response by an average of 4 dB across frequencies. However, in some cases (12 of 31) the response increased after insertion. The subsequent hearing loss was greater than the acute loss in the ECoG, averaging 22 dB across the same frequency range (250-1,000Hz). There was no correlation between the change in the ECoG response and the corresponding change in audiometric threshold.ConclusionsIntraoperative ECoG is a sensitive method for detecting electrophysiologic changes during implantation but had limited prognostic value regarding hearing preservation in the current conventional cochlear implant patient population where hearing preservation was not intended.Level of Evidence2b Laryngoscope, 126:1193-1200, 2016