Effects of Age at 2nd Implantation on Word-In-Noise Recognition for Children with Sequential Bilateral Cochlear Implantation

Abstract

The purpose of this study was to identify whether children with sequential bilateral cochlear implants (CIs) could receive additional benefit from the 2nd CI for the word-in-noise recognition, and the benefit from 2nd CI would be affected by age at 2nd implantation during 1-year use of the 2nd implant device. Eighteen children who received sequential bilateral CIs participated in this study. Among 18 participants, 9 children received the 2nd implantation before 8 years of age (earlier implanted) and the others had the 2nd implantation after 8 years of age (later implanted). Since this study aimed to explore whether earlier 2nd implantation improves effectiveness to use bilateral CIs in terms of word-in-noise recognition when compared to later 2nd implantation, the amount of additional perceptual benefit provided by 2nd CI was calculated as the difference in performance between the 1st CI and the bilateral CIs. The benefit was evaluated in four listening conditions (in quiet, 10, 0, and -10 dB signal-to-noise ratios). Results showed that overall, earlier implanted children had a greater amount of benefit from 2nd implantation compared to later implanted children, at least for word-in-noise recognition. Only for earlier implanted children, the benefit from 2nd implant continued to grow up over 12-month use of bilateral implants. The benefit from 2nd implant was greater for 0 dB SNR condition compared to in quiet or ?10 dB SNR conditions. In conclusion, although all participants were good performers (> 60%) with 1st CI alone, the 2nd implant provided additional perceptual benefit to word recognition in challenging listening conditions such as in the presence of background noise. Among various factors, age at 2nd implantation was a significant preoperative factor to predict the benefit from the use of sequential bilateral implants.