Garrett Cardon

Purpose Auditory threshold estimation using the auditory brainstem response or auditory steady state response is limited in some populations (e.g., individuals with auditory neuropathy spectrum disorder [ANSD] or those who have difficulty remaining still during testing and cannot tolerate general anesthetic). However, cortical auditory evoked potentials (CAEPs) can be recorded in many such patients and have been employed in threshold approximation. Thus, we studied CAEP estimates of auditory thresholds in participants with normal hearing, sensorineural hearing loss, and ANSD. Method We recorded CAEPs at varying intensity levels to speech (i.e., /ba/) and tones (i.e., 1 kHz) to estimate auditory thresholds in normal-hearing adults (<i>n</i> = 10) and children (<i>n</i> = 10) and case studies of children with sensorineural hearing loss and ANSD. Results Results showed a pattern of CAEP amplitude decrease and latency increase as stimulus intensities declined until waveform components disappeared near auditory threshold levels. Overall, CAEP thresholds were within 10 dB HL of behavioral thresholds for both stimuli. Conclusions The above findings suggest that CAEPs may be clinically useful in estimating auditory threshold in populations for whom such a method does not currently exist. Physiologic threshold estimation in difficult-to-test clinical populations could lead to earlier intervention and improved outcomes.

Objective The benefit of hearing aids as a clinical intervention strategy for children with Auditory Neuropathy Spectrum Disorder (ANSD) remains controversial. The goal of this study was to determine whether amplification through hearing aid use increased cortical phase synchrony in children with ANSD.<br>Design Using inter-trial coherence (ITC) of the EEG signal as a measure of cortical phase-locking, we examined differences in cortical phase synchrony in children with ANSD using both cross-sectional and longitudinal designs.<br>Study Sample Participants in the cross-sectional and longitudinal portions of the study included 58 and 16 children with clinical diagnoses of ANSD, respectively.<br>Results Results in the cross-sectional portion of the study revealed no significant difference in ITC between unaided and aided children. Overall, longitudinal data revealed no significant increase in ITC over time with hearing aid use. However, half of the subjects in the longitudinal sample showed a significant decrease in ITC from the unaided to the aided conditions.<br>Conclusions Overall, our results suggest that hearing aids may not be a beneficial intervention strategy for increasing cortical neural synchrony in all cases of ANSD and that amplification may actually reduce cortical phase-locking in some children with ANSD. The clinical implications of these findings are discussed.