The Relationship between Electrically Evoked Compound Action Potential and Speech Perception in CI24RE Implant Users

Abstract

Background and Objectives : Since performance with a cochlear implant is negatively correlated with an individual's duration of deafness prior to implantation, neural survival may be an important factor in determining outcome. To date, studies relating physiological measures such as the threshold and growth of the electrically evoked potentials have not shown clear relationships to human speech perception abilities, although there are positive results correlating these measures to nerve survival in animals. The primary goal of this study was to determine the extent to which the growth functions of electrically evoked compound action potential (ECAP) are related with speech perception performance in recent CI24RE implant users and to investigate the relationship between ECAP growth function and performance according to more limited electrodes. Subjects and Method : We measured ECAP growth functions to biphasic pulses using reverse neural telemetry system in 21 CI24RE implant users. For each subject, the slope of the growth function was compared with speech perception tests. In addition, this measure was also evaluated for a more limited set of electrodes. Results : Significant correlations have been found between the slope of ECAP growth functions and speech performance in CI24RE implant recipients. In addition, a relatively strong correlation has been found between the slope of ECAP growth function and performance on word recognition test in the group of basal electrodes. Conclusion : Effectiveness of the cochlear implant can be quite variable. These results show that ECAP measure may be useful in developing a test for predicting the outcomes of using the implant.