Supplementary Material for: Performance of Sequentially Bilateral Cochlear Implanted Children Who Speak Mandarin

Introduction: Cochlear implantation is an effective treatment for children with deafness. Although the binaural effect of bilateral cochlear implantation on sound localization and speech perception in noisy environments has been demonstrated, the outcome and performance predictors of the second cochlear implant (CI2) remain uncertain for patients receiving sequential implantation. This study evaluated the hearing performance between the first cochlear implant (CI1), CI2, and bilateral cochlear implants (CI1+2) among children with sequential bilateral cochlear implantation. Methods: This single-center retrospective study enrolled 14 children and adolescents aged 8–18 years who underwent sequential bilateral cochlear implantation with a mean interimplant interval of 8.2 years. The Mandarin Lexical Neighborhood Test (M-LNT), the Mandarin Hearing in Noise Test (M-HINT), and the Comprehensive Cochlear Implant Questionnaire (CCIQ) scores of participants were evaluated. Mann-Whitney U tests and Spearman correlation analysis were performed to analyze factors associated with CI2 performance. Results: In the 1-year follow-up period after CI2 implantation, although the M-LNT mean score for CI2 was significantly lower than that for CI1, the M-LNT scores for CI2 and CI1+2 improved significantly over time. In a noisy environment, CI1+2 significantly outperformed CI1 in the M-HINT. The M-LNT score for CI2 was significantly associated with preoperative bimodal fitting, residual hearing of the second implanted ear, and CI2 daily-usage time. Specific to CI2, the CCIQ showed improvement 1 year after CI2 implantation. Conclusion: CI2 improved the hearing performance and quality of life of recipients with longer interimplant intervals, especially in noisy environments, and its efficacy was associated with preoperative bimodal fitting and regular daily use.