Auditory brainstem response to paired clicks as a candidate marker of cochlear synaptopathy in humans

Objective: This study aimed to evaluate whether auditory brainstem response (ABR) using a paired-click stimulation paradigm could serve as a tool for detecting cochlear synaptopathy (CS). Methods: The ABRs to single-clicks and paired-clicks with various inter-click intervals (ICIs) and scores for word intelligibility in degraded listening conditions were obtained from 57 adults with normal hearing. The wave I peak amplitude and root mean square values for the post-wave I response within a range delayed from the wave I peak (referred to as the RMS_post-w1) were calculated for the single- and second-click responses. Results: The wave I peak amplitudes did not correlate with age except for the second-click responses at an ICI of 7 ms, and the word intelligibility scores. However, we found that the RMS_post-w1 values for the second-click responses significantly decreased with increasing age. Moreover, the RMS_post-w1 values for the second-click responses at an ICI of 5 ms correlated significantly with the scores for word intelligibility in degraded listening conditions. Conclusions: The magnitude of the post-wave I response for the second-click response could serve as a tool for detecting CS in humans. Significance: Our findings shed new light on the analytical methods of ABR for quantifying CS.