Auditory brainstem response with click and CE-Chirp® Level Specific stimuli in hearing infants

Introduction: The assessment of the integrity of the neural responses with ABR, aims to assist in the differential diagnosis of retrocochlear alterations. The gold standard stimulus for this assessment is Click. However, the CEChirp (R) Level Specific was developed to optimize the triggering of neural responses. Objective: to compare neural responses obtained with CE-Chirp (R) LS stimulus to those obtained with Clicks at 70 dB nHL in hearing infants, in order to analyze advantages in using CE-Chirp (R) LS. Methods: Eighteen infants with normal hearing were evaluated with Eclipse EP25 ABR System. Clicks and CEChirp (R) LS stimuli were presented using ER-3A insert earphones at 70 dB nHL, rate 45.1/s, and alternating polarity. A 30 Hz high-pass and 1500 Hz low-pass filter was applied, and +/- 40 mu V artifact rejection level. Absolute latency of waves I, III and V and their interpeak intervals I-III, III-V and I-V were measured, as well as interaural difference for wave V and interpeak I-V, and wave V amplitude. Results: Although 18 infants were included in the study, it was possible to collect data only in 30 ears for Click stimulus, and 33 ears for CE-Chirp (R) LS, according to exclusion criteria. It was possible to record waves I, III, and V for both stimuli at 70 dB nHL in all normal-hearing infants. CE-Chirp (R) LS stimulus evoked a higher wave V amplitude than Click (p < 0.001). Wave I absolute latency was statistically different between stimuli (p < 0.001), being delayed for CE-Chirp (R) LS. Wave III absolute latency was statistically different between stimuli only for the right ear (p = 0.021), and wave V absolute latency was similar in both stimuli (p = 0.210). Interpeak intervals IIII and I-V were statistically different between stimuli (p < 0.001), being reduced for CE-Chirp (R) LS. Interpeak interval III-V was different between the stimuli only for right ears (p = 0.006). There was no difference between stimuli for interaural difference wave V (p = 1.33) and interaural difference interpeak I-V (p = 0.409). Conclusion: It is possible to use CE-Chirp (R) LS stimulus in order to analyze neural synchrony in infants at 70 dB nHL, since better morphology waveforms were observed, and higher wave V amplitudes could be recorded. We suggest that new studies with infants with neurological disabilities and various hearing status, to observe how CE-Chirp (R) LS stimulus evokes neural responses in these conditions.