Summary of results using the nucleus CI24M implant to record the electrically evoked compound action potential

Objective: This study outlines a series of experiments using the neural res ponse telemetry (NRT) system of the Nucleus CI24M cochlear implant to measu re the electrically evoked compound action potential (EAP). The goal of thi s investigation was to develop a protocol that allows successful recording of the EAP in a majority of CI24M cochlear implant users. Design: Twenty-six postlingually deafened adults participated in this study . A series of experiments were conducted that allowed us to examine how man ipulation of stimulation and recording parameters may affect the morphology of the EAP recorded using the Nucleus NRT system. Results: Results of this study show consistent responses on at least some e lectrodes from all subjects. Cross-subject and cross electrode variations i n both the growth of the response and the temporal refractory properties of the response were observed. The range of stimulus and recording parameters that can be used to record the EAP with the Nucleus NRT system is describe d. Conclusions: Using the protocol outlined in this study, it is possible to r eliably record EAP responses from most subjects and for most electrodes in Nucleus CI24M: cochlear implant users. These responses are robust and recor ding these responses does not require that the subject sleep or remain stil l. Based on these results, a specific protocol is proposed for measurement of the EAP using the NRT system of the CI24M cochlear implant. Potential cl inical implications of these results are discussed.