Developmental changes of ABR wave 5 latency to click and tonal stimulation at different intensities in infants

Abstract

Abstract Background The ABR is useful for estimation of hearing thresholds and is considered an objective test since cooperation of the infant is not required. However, wave 5 identification and threshold determination are often based on the audiologist's subjective judgement. The aim of the present study is to describe the developmental changes in ABR wave 5 latency to different stimuli and intensities in infants of different ages. Materials and methods Data from the files of 294 normal hearing infants were used in a retrospective analysis. The latency of wave 5 brainstem component of the ABR to click and tonal stimuli at different intensities down to threshold were measured. Results The wave 5 latency to click was shorter than for tonal stimuli. Furthermore, the rate at which latency of wave 5 decreased as a function of stimulus intensity was more pronounced over the higher intensities. The shortening of wave 5 latency was also more rapid over the first few months in response to the higher frequencies. Discussion and conclusions Latency values obtained were similar to those described in the literature; wave 5 latency for different frequencies followed the tono-topic organization of the cochlea and the decrease in latency followed neural maturation. Further investigation is needed to determine if the latency values at threshold in infants with hearing loss are similar.