Electrophysiological study of hearing in full-term small-for-gestational-age newborns

Auditory Pathway Maturation in Full-term Small for Gestational Age Children: A Systematic Review with Meta-analysis

Introduction  Factors of intrauterine growth restriction have been responsible for the births of full-term babies small for their gestational age (SGA). Scientific evidence points that this restriction can cause changes in the neural maturation process. Objectives  To analyze the absolute latencies and interpeak intervals of brainstem auditory evoked potential waves in full-term and SGA children to investigate whether there are changes of neural maturation in this population. Data Synthesis  The search for articles that reported the assessment of brainstem auditory evoked potential in SGA newborns compared with a control, appropriate for their gestational age, both born full-term, for the entire period available in the database research until October 31, 2021 was performed based on the MEDLINE/PubMed Central and on the Latin America and the Caribbean Health Sciences Literature and Virtual Health Library electronic databases. A total of 311 studies were found in the database research. Out of this total, 10 studies were included in the review, 5 of which were eligible for the meta-analysis, involving a total of 473 participants of both genders, with 193 participants belonging to the study group and 280 to the control group. Differences between the groups were only observed in the absolute latency of wave V (95% confidence interval [CI]: 0.02-0.15; p  < 0.01). Conclusion  The SGA condition is responsible for the appearance of brainstem neural conduction dysfunction measured by the brainstem auditory evoked potentials, probably by the maturation process of the auditory pathway of this population.

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 CE-Chirp® Level Specific was developed to optimize the triggering of neural responses.

OBJECTIVE

to compare neural responses obtained with CE-Chirp® LS stimulus to those obtained with Clicks at 70 dB nHL in hearing infants, in order to analyze advantages in using CE-Chirp® LS.

METHODS

Eighteen infants with normal hearing were evaluated with Eclipse EP25 ABR System. Clicks and CE-Chirp® 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 μV 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® 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® 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® 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 I-III and I-V were statistically different between stimuli (p < 0.001), being reduced for CE-Chirp® 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® 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® LS stimulus evokes neural responses in these conditions.

Auditory brainstem response in neonates: influence of gender and weight/gestational age ratio

OBJECTIVE

To investigate the influence of gender and weight/gestational age ratio on the Auditory Brainstem Response (ABR) in preterm (PT) and term (T) newborns.

METHODS

176 newborns were evaluated by ABR; 88 were preterm infants - 44 females (22 small and 22 appropriate for gestational age) and 44 males (22 small and 22 appropriate for gestational age). The preterm infants were compared to 88 term infants - 44 females (22 small and 22 appropriate for gestational age) and 44 males (22 small and 22 appropriate for gestational age). All newborns had bilateral presence of transient otoacoustic emissions and type A tympanometry.

RESULTS

No interaural differences were found. ABR response did not differentiate newborns regarding weight/gestational age in males and females. Term newborn females showed statistically shorter absolute latencies (except on wave I) than males. This finding did not occur in preterm infants, who had longer latencies than term newborns, regardless of gender.

CONCLUSIONS

Gender and gestational age influence term infants' ABR, with lower responses in females. The weight/gestational age ratio did not influence ABR response in either groups.