Cochlear Implant Outcomes: A Comparison between Irradiated and Non-irradiated Ears

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 radiotherapy 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 -DeltaNI 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%, -DeltaNI=16.3%); ease of communication, 67.0% (58.36%, -DeltaNI=37.5%); background noise, 53.2% (44.14%, -DeltaNI=26.8%); reverberation, 41.7% (28.85%, -DeltaNI=32.7%); and aversiveness, -46.2% (-67.80%, -DeltaNI=-56.9%). The SDS was 66.9% (56.02%, -DeltaNI=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 -DeltaNI 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.

Outcome of early cochlear implantation

<p><b>INTRODUCTION</b>Universal newborn hearing screening facilitates early detection of congenital hearing loss. A child found to have severe to profound hearing loss may require a cochlear implant to access sounds in the speech frequency range.</p><p><b>MATERIALS AND METHODS</b>This retrospective study compared the speech perception outcomes of children implanted at 2 years and below (C1) with those implanted later (C3). Baseline and post-implant speech perception scores were recorded using IT-MAIS, TACL-R or PPVT. The percentage of improvement was calculated for each group and statistical significance was determined using the Student's t-test.</p><p><b>RESULTS</b>The median follow-up period for C1 (n = 29) and C3 (n = 29) was 29 months (range, 6 to 29 months) and 20 months (range, 5 to 32 months) respectively, which was not statistically significant. Although both groups recorded post-implant improvement of speech reception scores, the difference in the degrees of improvement was statistically significant (P = 0.034).</p><p><b>CONCLUSION</b>More rapid development of speech perceptive skills was achieved in children who were implanted early. Early implantation therefore, enables children to develop good core listening skills and to potentially develop spoken language at a young age. This enhances successful integration into mainstream pre-schools which provide the environment for the early nurturing of social and cognitive skills.</p>