Objective: To compare the results of auditory steady-state response (ASSR) and click auditory brainstem response (click ABR) among infants and young children tested at the Ear Unit of a Tertiary General Hospital.
Methods:
Design: Cross-sectional Study
Setting: Tertiary General Hospital
Population: Within-subject comparisons of click auditory brainstem response (click ABR) thresholds and auditory steady-state response (ASSR) thresholds among 55 infants and young children, 2 months to 35 months of age referred to the Ear Unit for electrophysiologic hearing assessment.
Results: Click ABR showed strong positive correlation to all frequencies and averages of ASSR. Highest correlation was noted with the average of 1-4 kHz ASSR results with Pearson r = 0.89 (Spearman r=0.80), the average of 2-4 kHz had strong positive correlation r = 0.88 (0.79). Correlation was consistently strong through all ASSR frequencies (0.5 kHz at r=0.86 (0.74), 1 kHz at r=0.88 (0.78), 2 kHz at r=0. 87 (0.79), 4 kHz at r=0.85 (0.76)). Average differences of click ABR and ASSR thresholds were 8.2±12.9dB at 0.5 kHz, 8.6±12.6dB at 1 kHz, 5.3±11.8dB at 2 kHz and 7.8±13.4dB at 4 kHz. Among patients with no demonstrable waveforms by click ABR with maximal click stimulus, a large percentage presented with ASSR thresholds. Of these, 80.5% (33 of 41) had measurable results at 0.5 kHz with an average of 107.3±11.1dB, 85.4% (35 of 41) at 1 kHz with an average of 110.5±11.8dB, 73.2% (30 of 41) at 2 kHz with an average of 111.2±11.1dB and 63.4% (26 of 41) at 4 kHz with and average of 112.2±8.21dB. Auditory steady-state response results were comparable to auditory brainstem response results in normal to severe hearing loss, and provided additional information necessary for complete audiologic assessment especially among patients with severe to profound hearing loss wherein click ABR showed no responses. Up to 85.4% of patients that would have been noted to have no waveforms by click ABR still demonstrated measurable thresholds by ASSR
Conclusion: Our study suggests that ASSR may be the best available tool for assessing children with severe to profound hearing loss, and is a comparably effective tool in overall hearing assessment for patients requiring electrophysiological testing. The advantages of ASSR over click ABR include: 1) detection of frequency-specific thresholds and; 2) the detection of hearing loss thresholds beyond the limits of click ABR.
Key words: Auditory Steady-State Response, ASSR, Auditory Brainstem-Evoked Response, ABR, Hearing Thresholds, Electrophysiologic Testing
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