Outcome of cochlear implantation in the worse ear of post-lingual asymmetric hearing loss: elucidation of prognostic markers

Abstract

Background Specific correlations between the outcomes of cochlear implantation (CI) and hearing thresholds of the both ears in post-lingual asymmetric hearing loss (AHL) patients were not clear. Aims/Objectives To identify the variables influencing the outcome of CI in post-lingual AHL patients. Method We included 18 adult subjects who had CI in the worse ear due to post-lingual AHL with average hearing asymmetry of 36 dB. Speech perception scores were evaluated in the sound field with hearing aid on the better ear before CI, and with the cochlear implant in the worse ear at 3, 6, and 12 months after CI switch-on. Results Average increases in phonetically balanced word score, spondee word score, and everyday sentence score at 12 months from CI switch-on compared with those before CI were 38.9%p, 46.2%p, and 52.4%p, respectively. Multiple linear regression analysis showed that speech perception scores were negatively influenced by age at implantation and hearing threshold difference of both ears (HTD-Both) itself, rather than the worse or better ear hearing thresholds. Conclusions and significance Post-lingual AHL subjects with high average hearing asymmetry can benefit from CI in the worse ear, while CI outcomes can be adversely influenced by HTD-Both and age at implantation both in the short- and long-term follow-up.