Evaluation of ECAP thresholds, T and C levels in children with sequential bilateral cochlear implants

Abstract

Aim: The aim of the present study was to compare the values in threshold (T) and comfortable (C) stimulation levels as well as the neural response telemetry (NRT) measurements obtained on the first and the second cochlear implant in children with sequential bilateral cochlear implantation (CI). Material and Methods: Thirty children with sequential bilateral CI between February 2007 and July 2018 were randomly selected. The mean age of the subjects was 7.0 years (age range: 3.3–15.2 years). The NRT thresholds, T levels, and C levels in the electrode (E) 22, E16, E11, E6, and E1 were retrospectively compared for the latest program on the first CI (CI1), and the second CI (CI2) in the postoperative 1st, 3rd, and 6th-month follow-up visits. The duration of daily use of the speech processor on both side was also compared.Results: Twelve male and eightteen female subjects with sequential bilateral CI, were participated in the present study. The median age at CI1 was 15 months and 5 years 5 months for CI1 and CI2 respectively. There was no significant difference between the threshold NRT (tNRT) levels between two ears. The mean tNRT levels were obtained 166 CL and 179 CL in E22 and E1 respectively. The tNRT levels were found higher on the basal electrode rather than the apical electrode (p=0.02). The changes in the T and C levels were significant in 1st, 3rd, and 6th-month follow-up visits on the CI2 side (p=0.000). The mean daily usage time of the sound processor was found 12.05 and 9.62 hours on CI1 and CI2 respectively. Conclusion: In children with sequential CI, the electrical stimulation levels were similar between ears. The present study shows the programming outcomes during the follow-up in children with sequential bilateral CI. Keywords: Hearing loss; cochlear implant; sequential surgery; bilateral cochlear implantation; neural response telemetry.