Cochlear Implant Outcome Is Not Influenced by the Choice of Ear

In Brief Objectives: This study tested the hypothesis that patients with residual hearing in the nonimplanted ear had the same cochlear implant benefit whether the implanted ear had profound or severe hearing loss. Design: A retrospective chart review of adult cochlear implant recipients with postlingual hearing loss. Patients were categorized according to the pure-tone average of the implanted and contralateral ears as (a) bilateral profound, (b) severe-profound, and (c) bilateral severe. The results of a test battery of spoken language measures were compared among patients belonging to these hearing categories at 6, 12, and 24 months after surgery, using a t-test and multivariate regression analyses. Results: The presence of residual hearing in one or both ears was associated with significantly higher postoperative speech perception scores compared with participants with bilateral profound hearing loss. Among participants with similar amounts of residual hearing in the nonimplanted ear, however, there was no difference in speech recognition scores between those with profound and those with severe hearing loss in the implanted ear. Conclusions: Among participants with asymmetric hearing loss, there is no additional benefit to implanting the better-hearing ear that can be preserved for use with a hearing aid for better speech understanding in noise and sound localization. These results suggest that the additional benefit received by patients with residual hearing is mediated by trophic effects on crossed pathways in the central nervous system and is independent of the preoperative functional status of the implanted ear. The better-hearing ear has frequently been chosen for cochlear implantation because of the unproven idea that better neural preservation in this ear would equate to better speech perception outcomes. We propose, however, that the audiological advantage of residual hearing in a patient with asymmetric severe and profound hearing loss is not negatively impacted by implanting the ear with profound hearing loss. The speech recognition scores of individuals with bilateral severe hearing loss, asymmetric severe and profound hearing loss, and bilateral profound hearing loss were compared at 6, 12 and 24 months after surgery. Participants with asymmetric severe and profound hearing loss had the same speech recognition in quiet and noise whether the better- or worse-hearing ear was implanted, and were similar to individuals with bilateral severe hearing loss. These observations suggest that the worse-hearing ear can be implanted without compromising speech understanding, while preserving residual hearing in the contralateral ear for the use of a hearing aid or future technologies.