Utility of auditory steady-state response in differentiating pediatric auditory neuropathy spectrum disorders: with normal auditory nerve diameter versus with auditory nerve hypoplasia.

Purpose: Evaluations of Auditory Evoked Potentials, more specifically Auditory Steady-State Responses (ASSR) in children having Auditory Neuropathy Spectrum Disorder (ANSD) with normal auditory nerve diameter and ANSD with auditory nerve hypoplasia were performed, to analyze the feasibility of using ASSR as a predictor of behavioral thresholds in this population.

Methods: In total, 27 children were evaluated; 17 diagnosed as ANSD with normal auditory nerve diameter (group 1) and 10 diagnosed as ANSD with auditory nerve hypoplasia (group 2). The participants' ages ranged from six months to 10 years and 9 months, and all had bilateral alterations; therefore, 54 ears were analyzed. The evaluation included (i) ASSR thresholds, in carrier frequencies of 0.5, 1, 2 and 4 kHz, 100 % modulated for amplitude and 20 % for frequency and (ii) behavioral auditory thresholds.

Results: Among children having ANSD with normal auditory nerve diameter, a high number of absent responses was identified in ASSR, even at frequencies with behavioral threshold records. Conversely, among children having ANSD with auditory nerve hypoplasia, consistent ASSR were recorded, making it possible to determine the electrophysiological threshold for most frequencies evaluated in this study.

Conclusion: In ANSD with normal auditory nerve diameter, ASSR do not provide additional information for predicting behavioral thresholds, requiring follow-up until the obtainment behavioral thresholds. Conversely, ASSR were consistently recorded in cases of ANSD with auditory nerve hypoplasia. Therefore, ASSR is a promising complementary tool for differential diagnosis between hypoplasia and auditory nerve aplasia and even between ANSD with normal auditory nerve diameter and ANSD with auditory nerve hypoplasia.