Effect of cochlear implant electrode array design on auditory nerve and behavioral response in children

AimTo study the effect of change in the array design of cochlear implant electrode on electrophysiological, and behavioral functional measures of cochlear implant users.MethodA total of 33 children using cochlear implants were included in this study. Subjects were implanted with different electrode types including Slim Straight (CI422) and Freedom Contour Advance (CI24RE) electrode arrays. The electrically evoked compound action potential (ECAP) thresholds were evoked by stimulation of basal, mid, and apical electrodes. The behavioral aided responses using the implant were obtained about 6–12 months post fitting of implant.ResultsECAP thresholds decreased significantly postoperatively in both electrode arrays. Slim straight electrode (CI422) had higher thresholds than Freedom Contour Advance (CI24RE) electrode at most recording sites, but the differences were only significant at basal site. This is a direct consequence of a perimodiolar electrode versus a lateral wall electrode, i.e., the neurons are further away requiring more current (higher threshold) to record the NRT.ConclusionAlthough the curved electrode array appeared to evoke responses at lower thresholds, effect on patient performance was not obvious.