Cochlear implant outcomes: A comparison between irradiated and non-irradiated ears

Abstract

Objectives: Radiotherapy for head and neck tumors is known to potentially induce sensorineural hearing loss, which is possibly due to damage to the cochlear and/or auditory pathways. Since the success of cochlear implantation depends on a functional auditory nerve, this paper aims to study the hearing outcomes of cochlear implantation in irradiated ears. Methods: A retrospective study of cochlear implant recipients from our institution who had previously received radiothera-py for head and neck cancers was performed. A control group with cochlear implants who did not receive radiotherapy was recruited. A review of case records, speech discrimination scores (SDS), and a validated subjective questionnaire in the form of the Abbreviated Profile of Hearing Aid Benefit (APHAB) was/administered to the study group who fulfilled the inclusion criteria. Global and category scores in both groups were averaged and statistically compared via non-inferiority (NI) testing. Results: With the control group (n=8) as the reference, the -δNI was defined, and a one-tailed lower 95% confidence interval was used for the irradiated group (n=8). The APHAB degree of improvement (%) results were as follows: global, 28.9% (19.32%, -δNI=16.3%); ease of communication, 67.0% (58.36%, -δNI=37.5%); background noise, 53.2% (44.14%, -δNI=26.8%); reverberation, 41.7% (28.85%, -δNI=32.7%); and aversiveness, -46.2% (-67.80%, -δNI= -56.9%).The SDS was 66.9% (56.02%, -δNI=51.0%). From the results, lower 95% confidence interval limits of global APHAB, SDS, ease of communication, and background noise scores of the irradiated group were within the defined -δNI boundary and hence are not inferior to the control. The categories of reverberation and aversiveness could not be proven, however. Conclusion: This study demonstrated marked improvements in hearing measured both objectively and subjectively. The overall hearing outcomes after cochlear implantation for post-irradiated patients were not worse than patients who have had no prior irradiation to ear structures. Copyright © 2012 by Korean Society of Otorhinolaryngology-Head and Neck Surgery.