Intra and postoperative electrocochleography in cochlear implant recipients: retrospective chart review

Abstract

Objectives: The purpose of the study was (1) to retrospectively analyze ECochG data and compare it with the current literature. (2) to explore the relationship between ECochG and post-op audiological assessments.

Methods: This retrospective study included all patients with intraoperative and postoperative ECochG measurements and postoperative audiologic testing. ECochG were performed during CI insertion regardless of the preoperative hearing status. Preoperative and postoperative assessments were extracted from the medical records.

Results: A total of 35 patients (42 ears) met the inclusion criteria. Intra-op ECochG response was measurable in 17 of 42 ears (40.5%). The mean peak amplitude found was 103.3 µvolts. The type of electrode array was not associated with the ECochG amplitude (p = .630). Post-op ECochG thresholds were significantly correlated with behavioral thresholds after a month of CI implantation (p < 0.05).

Conclusions: ECochG responses were measurable in individuals with mean preop pure tone thresholds of 66 dB HL at 250 Hz, 77 dB HL at 500 Hz, 84 dB HL at 1 kHz and 92 dB HL at 2kHz. The type of electrode was not associated with the ECochG peak nor with greater preservation of residual hearing. Post-op ECochG thresholds were significantly correlated with post-op thresholds.

Keywords: Cochlear implants; hearing preservation; intracochlear electrocochleography; intraoperative electrocochleography; sensorineural hearing loss.