Intraoperative evoked potentials monitoring for cochlear implantation in common cavities

Abstract

Objectives: To determine the efficacy of intraoperative evoked compound action potential (ECAP) monitoring for optimal electrode placement and postoperative programming in cochlear implantation for patients with common cavity malformations. Methods: Retrospective case review of 1 child with a common cavity malformation undergoing revision cochlear implantation with a Clarion HiRes 90K™ implant. Outcome measures included neural response amplitude curves from intraoperative ECAP for each of 16 independent output circuits. Postoperative ECAP aided in mapping configuration to adjust threshold (T) and most comfortable loudness (M) levels across hearing frequencies. Results: Intraoperative ECAP confirmed proximity of the electrode to the neural response elements in this child with a common cavity defect by demonstrating expected neural response amplitudes across 10 of the 16 independent output circuits. No intraoperative repositioning of the electrode was required. Postoperative computed tomography imaging confirmed the location of electrodes with present ECAP responses to be along the medial most wall of the cavity. Postoperative ECAP aided the adjustment of mapping configuration to optimize threshold levels across frequencies for this child. Conclusion: Intraoperative ECAP can aid placement of a cochlear electrode in patients with common cavity malformations, particularly when the location of the neural response elements within the malformed otic capsule are unknown. ECAP can also assist in optimizing the postoperative mapping configurations in these patients.