Clin Exp Otorhinolaryngol.  2012 Apr;5(Suppl 1):S93-S98.

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

• Soh JM
• D'Souza VD
• Sarepaka G
• Ng WN
• Ong CS
• Low WK

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 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.

Keyword

Hearing loss; Deafness; Cochlear implant; Nasopharyngeal carcinoma; Radiotherapy; Irradiation

MeSH Terms

Auditory Pathways
Cochlear Implantation
Cochlear Implants
Cochlear Nerve
Deafness
Ear
Head
Hearing
Hearing Aids
Hearing Loss
Hearing Loss, Sensorineural
Humans
Nasopharyngeal Neoplasms
Neck
Noise
Retrospective Studies
Speech Perception
Surveys and Questionnaires
Nasopharyngeal Neoplasms

Figure

• 

  Fig. 1 Mean responses for Abbreviated Profile of Hearing Aid Benefit (APHAB) & speech discrimination scores (SDS) for both the irradiated and control groups in the unaided listening condition prior to their cochlear implantation. EC, ease of communication; BN, background noise; RV, reverberation; AV, aversiveness. Error bars, +/- 1 SD.

• 

  Fig. 2 Mean responses for Abbreviated Profile of Hearing Aid Benefit (APHAB) & speech discrimination scores (SDS) for both the irradiated and control groups in the aided listening condition status post cochlear implants (CI) with a minimum of 1 year of usage of the CI prior to being inducted into the study. EC, ease of communication; BN, background noise; RV, reverberation; AV, aversiveness. Error bars, +/- 1 SD.

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  Fig. 3 Comparison of the mean degree of hearing benefit for the irradiated and control groups. EC, ease of communication; BN, background noise; RV, reverberation; AV, aversiveness; SDS, speech discrimination scores. Error bars, +/- 1 SD.

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  Fig. 4 Non-inferiority diagram depicting the mean differences for each subcategory of Abbreviated Profile of Hearing Aid Benefit between the irradiated and control groups.

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  Fig. 5 Non-inferiority diagram depicting the mean differences for speech discrimination score (SDS) subcategory between the irradiated and control groups.

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