Outcomes in adolescents from sequential vs bilateral cochlear implantation in young children

Objective: To investigate whether early simultaneous vs sequential bilateral cochlear implantation affects long-term hearing outcomes into adolescence and early adulthood. Methods: In this cross-sectional study, we compared performance in sound localization and speech recognition in quiet and in masking speech between adolescents with simultaneous or sequential bilateral cochlear implantation using linear mixed modeling. Participants were required to be aged 12 to 21 years, have received at least 1 cochlear implant before age 2.5 years, have an interval between the first and second cochlear implantation less than 4 years, attend a standard school curriculum, and have no cochlear malformation. Fifteen adolescents with normal hearing provided normative data. Results: Of 109 individuals from the Karolinska University Hospital medical records who were eligible based on the age and age at implantation criteria, 37 (34%) met all inclusion criteria and were willing to participate. Simultaneously implanted participants (n = 17) achieved higher sound localization accuracy than those who were sequentially implanted (n = 20) (P < .001; Cohen’s d = 0.58), whereas recognition of speech was comparable. Because both implant groups were consistent users of bilateral implants for on average 15 years, the interimplant delay was short for participants with sequential implants (mean = 1.2 years; 95% confidence interval, 0.29–3.5 years), and the groups were similar on a large number of social, environmental, and auditory factors before and after implantation; the higher localization accuracy is likely the result of simultaneous implantation. Both implant groups performed worse than adolescents with normal hearing. Conclusion: Simultaneous bilateral cochlear implantation in early childhood supports better long-term spatial hearing than sequential implantation.