Effect of Stimulus and Number of Sweeps on the Neonate Auditory Brainstem Response

Auditory Brainstem Response with the iChirp stimuli in the infant's audiological diagnosis

OBJECTIVE

to investigate the use of the iChirp stimulus in the infant's audiological diagnosis compared to stimuli typically used in the ABR in infants, in addition to suggesting reference values for the assessment of this population.

METHODS

62 infants participated in the study, 29 females and 33 males. The subjects underwent the recording of the Auditory Brainstem Response in the Smart Ep equipment, with the stimuli click, iChirp-broadband, tone burst and iChirp-narrowband, which were presented at three levels of intensity (20 dB, 40 dB and 60 dB) and, for tone burst and iChirp-narrowband stimuli, at different frequencies (0.5, 1 k, 2 k and 4 KHz). The data were later analyzed using Student's t-test.

RESULTS

In general, the iChirp-broadband and iChirp-narrowband stimuli showed higher latency values and greater amplitudes when compared to click and tone burst stimuli. Furthermore, better signal-to-noise ratios were observed when contrasting iChirp-narrowband with tone burst. Additionally, reference values were established for the assessment of ABR in infants with the iChirp-broadband and iChirp-narrowband in the Smart-Ep equipment.

CONCLUSION

The iChirp stimulus appears to be promising in the infant's audiological diagnosis, as its use promoted greater amplitudes and better wave morphology, which facilitates to mark the waveforms and provides greater efficiency in the investigation of the auditory thresholds. The indication of normative data also enables the clinical use of these stimuli in the infant's audiological diagnosis.

Effect of delivery mode on neonate auditory brainstem responses to air- and bone-conducted stimuli

OBJECTIVES

The object of this study was to examine if caesarean section delivered neonates have different middle ear function relative to neonates with vaginal delivery.

METHODS

Auditory brainstem responses (ABRs) were examined in caesarean section delivered (n = 23) and vaginally delivered (n = 29) neonates. ABRs were also evoked with air- and bone-conducted stimuli (i.e., clicks and CE-Chirps) and presented at a screening intensity level (i.e., 30 dB nHL). Wave V latencies and amplitudes were examined as a function of mode of delivery and stimuli.

RESULTS

Statistically significant longer wave V latencies evoked with air-conducted stimuli were seen in caesarean section delivered neonates (p = .042). There was no statistically significant difference in wave V latencies with bone-conducted stimuli among the two groups of neonates (p = .42). There were no significant differences in wave V amplitude between neonates with caesarean section and vaginal delivery for air-conducted (p = .42) stimuli. Wave V amplitudes were not significantly different as a function of mode of delivery with CE-Chirp stimulus (p = .41). Wave V amplitudes were significantly larger for the caesarean section delivered neonates with the bone-conducted click stimulus (p = .036).

CONCLUSIONS

The ABR wave V latency disparity with air- and bone-conducted stimuli support the notion that differences in middle ear function exist between the two groups of newborns. It was speculated that delayed fluid resorption in the middle ear exists in neonates with caesarean section delivery compared to those with vaginal delivery.

Neonate Auditory Brainstem Responses to CE-Chirp and CE-Chirp Octave Band Stimuli II: Versus Adult Auditory Brainstem Responses

OBJECTIVES

The purpose of the study was to examine the differences in auditory brainstem response (ABR) latency and amplitude indices to the CE-Chirp stimuli in neonates versus young adults as a function of stimulus level, rate, polarity, frequency and gender.

DESIGN

Participants were 168 healthy neonates and 20 normal-hearing young adults. ABRs were obtained to air- and bone-conducted CE-Chirps and air-conducted CE-Chirp octave band stimuli. The effects of stimulus level, rate, and polarity were examined with air-conducted CE-Chirps. The effect of stimulus level was also examined with bone-conducted CE-Chirps and CE-Chirp octave band stimuli. The effect of gender was examined across all stimulus manipulations.

RESULTS

In general, ABR wave V amplitudes were significantly larger (p < 0.0001) and latencies were significantly shorter (p < 0.0001) for adults versus neonates for all air-conducted CE-Chirp stimuli with all stimulus manipulations. For bone-conducted CE-Chirps, infants had significantly shorter wave V latencies than adults at 15 dB nHL and 45 dB nHL (p = 0.02). Adult wave V amplitude was significantly larger for bone-conducted CE-Chirps only at 30 dB nHL (p = 0.02). The effect of gender was not statistically significant across all measures (p > 0.05).

CONCLUSIONS

Significant differences in ABR latencies and amplitudes exist between newborns and young adults using CE-Chirp stimuli. These differences are consistent with differences to traditional click and tone burst stimuli and reflect maturational differences as a function of age. These findings continue to emphasize the importance of interpreting ABR results using age-based normative data.

Auditory Brainstem Response Thresholds to Air- and Bone-Conducted CE-Chirps in Neonates and Adults

PURPOSE

The purpose of this study was to compare auditory brainstem response (ABR) thresholds to air- and bone-conducted CE-Chirps in neonates and adults.

METHOD

Thirty-two neonates with no physical or neurologic challenges and 20 adults with normal hearing participated. ABRs were acquired with a starting intensity of 30 dB normal hearing level (nHL). The lowest stimulus intensity level at which a wave V was identifiable and replicable was considered the ABR threshold.

RESULTS

ABR thresholds to air-conducted CE-Chirps were 9.8 dB nHL for neonates and adults. ABR thresholds to bone-conducted CE-Chirps were 3.8 and 13.8 dB nHL for neonates and adults, respectively. The difference in ABR thresholds to bone-conducted CE-Chirps was significantly different (p < .0001, ηp2 = .45). Adults had significantly larger wave V amplitudes to air- (p < .0001, ηp2 = .50) and bone-conducted (p = .013, ηp2 = .15) CE-Chirps at a stimulus intensity of 30 dB nHL. At the same intensity, adults evidenced significantly shorter wave V latencies (p < .0001, ηp2 = .49) only with air-conducted CE-chirps.

CONCLUSION

The difference in ABR thresholds and wave V latencies to air- and bone-conducted CE-Chirps between neonates and adults may be attributed to a disparity in effective signal delivery to the cochlea.

Chirp-Evoked Auditory Brainstem Response in Children: A Review

PURPOSE

The aim of this study was to assess the use of the chirp stimulus to record auditory brainstem responses in the pediatric population via a traditional review.

METHOD

An electronic search of the literature and a hand search of the literature were conducted. Studies that utilized chirp stimuli within the pediatric population that met all of the inclusion criteria were included in this review. Qualitative synthesis and interpretation of the data were completed.

RESULTS

Seven studies that met the inclusion criteria were included in the review. Chirp stimuli produce auditory brainstem response (ABR) waveform amplitudes in children similar to those in adults when presented at moderate to low frequency levels. Latency data from chirp stimuli are not consistent when stimulus presentation rates are altered. Test-retest reliability when using the chirp stimulus was found to be good, as were sensitivity and specificity of chirp-evoked ABRs utilized in a newborn hearing screening protocol.

CONCLUSION

Reviewed studies indicated that when presented at 60 dB nHL or lower, broadband chirp-generated ABRs have larger amplitudes than click-generated ABRs in children with normal hearing. Utilization of chirp stimuli decreases test time because waveforms are easier to detect with increased synchronization. Further research should focus on correlating chirp thresholds with behavioral hearing thresholds. Given the variance of results in these select studies, future research should also evaluate latency findings and focus on developing normative data for infants with hearing impairment and normal hearing.