Article

Aiding and Occluding the Contra lateral Ear in Implanted Children with Auditory Neuropathy Spectrum Disorder

Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, WI, USA.
Journal of the American Academy of Audiology (Impact Factor: 1.59). 10/2011; 22(9):567-77. DOI: 10.3766/jaaa.22.9.2
Source: PubMed

ABSTRACT The challenges associated with auditory neuropathy spectrum disorder (ANSD) are due primarily to temporal impairment and therefore tend to affect perception of low- to midfrequency sounds. A common treatment option for severe impairment in ANSD is cochlear implantation, and because the degree of impairment is unrelated to degree of hearing loss by audiometric thresholds, this population may have significant acoustic sensitivity in the contralateral ear. Clinically, the question arises as to how we should treat the contralateral ear in this population when there is acoustic hearing-should we plug it, amplify it, implant it, or leave it alone?
The purpose of this study was to examine the effects of acute amplification and plugging of the contralateral ear compared to no intervention in implanted children with ANSD and aidable contralateral hearing. It was hypothesized that due to impaired temporal processing in ANSD, contralateral acoustic input would interfere with speech perception achieved with the cochlear implant (CI) alone; therefore, speech perception performance will decline with amplification and improve with occlusion.
Prospective within-subject comparison. Adaptive speech recognition thresholds (SRTs) for monosyllable and spondee word stimuli were measured in quiet and in noise for the intervention configurations.
Nine children treated at the Medical College of Wisconsin Koss Cochlear Implant Program participated in the study. Inclusion criteria for this study were children diagnosed with ANSD who were unilaterally implanted, had aidable hearing in the contralateral ear (defined as a three-frequency pure-tone average of ≤80 dB HL), had at least 1 yr of cochlear implant experience, and were able to perform the speech perception task.
We compared SRT with the CI alone to SRTs with interventions of cochlear implant with a contralateral hearing aid (CI+HA) and cochlear implant with a contralateral earplug (CI+plug).
SRTs were measured and compared within subjects across listening conditions. Within-subject comparisons were analyzed using paired t-tests, and analyses of predictive variables for effects of contralateral intervention were analyzed using linear regression.
Contrary to the hypothesis, the bimodal CI+HA configuration showed a significant improvement in mean performance over the CI-alone configuration in quiet (p = .04). In noise, SRTs were obtained for six subjects, and no significant bimodal benefit was observed (p = .09). There were no consistent effects of occlusion observed across subjects and stimulus conditions. Degree of bimodal benefit showed a significant relationship with performance with the CI alone, with greater bimodal benefit associated with poorer CI-alone performance (p = .01). This finding, however, was limited by floor effects.
The results of this study indicate that children with ANSD who are experienced cochlear implant users may benefit from contralateral amplification, particularly for moderate cochlear implant performers. It is unclear from these data whether long-term contralateral hearing aid use in real-world situations would ultimately benefit this population; however, a hearing aid trial is recommended with assessment of bimodal benefit over time. These data may help inform clinical guidelines for determining optimal hearing configurations for unilaterally implanted children with ANSD, particularly when considering candidacy for sequential cochlear implantation.

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    ABSTRACT: Objective Patients with auditory neuropathy spectrum disorder (ANSD) exhibit altered neural synchrony in response to auditory stimuli. Cochlear implantation (CI) is thought to improve neural synchrony in response to auditory stimuli and improve speech perception relative to conventional hearing amplification (HA).Study DesignRetrospective review.SettingTertiary otologic practice.Subjects and Methods Subjects included patients with ANSD treated at Vanderbilt University from 1999 to 2011. Sixteen patients underwent CI, and 10 received binaural HAs. Pretreatment performance was assessed through speech reception thresholds and parent questionnaire (Infant-Toddler Meaningful Auditory Integration Scale [IT-MAIS]). Posttreatment outcomes were assessed using IT-MAIS and closed-/open-set speech perception scores.ResultsTwo HA users underwent neuromaturation and were excluded from further analysis. For the remaining patients, median duration of device use was 48 months. All CI patients had a prior binaural HA trial with failure of auditory skills development. Median available pretreatment IT-MAIS score was 13 and 30 for CI and HA groups, respectively (rank sum test, P = .32). Posttreatment, 6 of 16 CI patients and 4 of 8 HA patients achieved open-set speech perception scores ≥60%. No differences between groups were found in posttreatment IT-MAIS scores (rank sum test, P = .11) or the percentage of patients achieving the above levels of open-set speech perception (Fisher exact test, P = .67).ConclusionsA wide range of speech perception outcomes are observed in ANSD patients. In our ANSD population, patients who exhibited failure of auditory skills development with HAs were able to achieve comparable overall speech perception outcomes after CI relative to those who continued to make appropriate auditory progress with HAs alone.
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