ABR latency in infants: properties and applications of various measures

Stability of ABR Wave V Threshold in Early Hearing Diagnostics in Children from Selected Groups at Risk of Congenital Hearing Loss

<b>Introduction:</b> Upon hearing that the "little" patient has trouble with hearing, we are mostly interested in the level of his hearing threshold. When the child is in the first year of life, results can only be achieved by means of ABR test. Subsequent control tests, especially in children from the hearing loss risk groups selected in this study, show that the obtained outcomes are subject to fluctuations. Their fluctuating nature is manifested by the instability of wave V threshold in subsequent diagnostic periods. Such variability often delays the implementation of the appropriate proceeding. Knowledge of the dissimilarity of behavior of the wave V threshold occurring in individual groups at risk of hearing loss allows for the correct interpretation of the obtained results, and thus, effective therapeutic measures. <br><b>Aim:</b> The aim of the paper is to analyze the stability of wave V threshold during the first year of life in children from selected risk groups for congenital hearing disorders. <br><b>Material and methods:</b> From the patient population of 2,114 individuals examined in 2015-2016 at a reference center participating in the Universal Neonatal Hearing Screening Program in 2015-2016, the results of 250 children were subjected to retrospective analysis. Furthermore, 4 groups of little patients were formed (children with Down syndrome; children with other diseases or damage to the nervous system; children with cleft palate or cleft lip and cleft palate; children with congenital cytomegaly) in whom diagnostic practice revealed variable results of the wave V threshold. We analyzed the results of tests obtained during the first year of the child's life divided into 4 diagnostic periods. <br><b>Results:</b> The highest percentage of instability in the established threshold of wave V between individual diagnostic periods occurred in the group of children with cleft palate or cleft lip and cleft palate. In the group of children with Down syndrome, it was observed that the instability of the ABR test results decreased over time. In the group of children with other diseases or damage of the nervous system, the highest percentage of the lack of stable ABR wave V thresholds was observed between the 1st and 2nd as well the 1st and 4th diagnostic periods. On the other hand, in the group of children with congenital CMV, there was a relatively low percentage of instability of results. <br><b>Conclusions:</b> (1) Although the ABR test is a diagnostic standard, in particular groups of patients the study is burdened with high variability of measurement results in subsequent diagnostic periods. Such a group of patients are children with cleft palate or cleft lip and cleft palate; therefore, it must receive particular attention in treatment planning; (2) in selected groups at risk of hearing loss, due to the high percentage of children with hearing impairment (70%), the validity of performing newborn hearing screening tests was confirmed.

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.

Gender effects in auditory brainstem responses to air- and bone-conducted clicks in neonates

Examinations of gender differences in auditory brainstem response (ABR) wave V latencies and thresholds to air- and bone-conducted clicks were undertaken with neonates. Two hundred and two full-term neonates participated (i.e., 103 males and 99 females). Wave V latency measures for air- and bone-conducted click stimuli of 30, 45, and 60 dB nHL and 15 and 30 dB nHL, respectively, and thresholds to air- and bone-conducted clicks were determined. Female newborns displayed statistically significant shorter wave V latencies than male newborns for air-conducted click stimuli (i.e., approximately 0.2-0.3 ms; P=.0016). There were no significant gender differences in wave V latencies to bone-conducted click stimuli (P=.11). With respect to ABR thresholds, no statistically significant differences were observed for either air-conducted clicks (P=.054) or bone-conducted clicks (P=.18).

EDUCATIONAL OBJECTIVES

As a result of this activity, the participant will be able to (1) describe gender differences in ABR wave V latencies and thresholds to air- and bone-conducted clicks with neonates and (2) summarize possible explanations for observed gender differences in ABR wave V latencies and thresholds to air- and bone-conducted clicks with neonates.

[Precocious maturation of auditory evoked potentials in prematures: influence of gestational age and sex]

In humans, the onset of the auditory function occurs at the beginning of the third trimester of pregnancy. Brainstem auditory evoked potentials (BAEPs) can be recorded in preterm neonates as early as 25-26 weeks of gestational age. The latency of BAEP waves show a significant decrease according to increasing age to achieve adult values at the end of the first month after birth for wave I and near 3 to 5 years old for waves III and V. Auditory evoked responses are influenced by gender, notably with significantly higher wave latencies in males than in females. These gender differences in auditory function appear early in humans, some being observed as soon as 34 weeks of gestational age.

Functional auditory development in preterm and full term infants

Bilateral ABRs were recorded from 452 infants 32-45 weeks conceptional age. Differences in laterality, gender and appropriateness for gestational age were investigated in order to increase our understanding of developmental processes in early life. Rate effects were also studied in a subsample of infants (145 ears). All subjects were free of conditions known to affect ABR parameters. Left/right differences were evident for all ABR measures except the amplitude of wave I. Shorter interwave intervals and larger amplitudes were consistently observed on the right. Females exhibited shorter absolute latencies for waves III and V and larger wave I amplitudes than males. Small for gestational age (SGA) infants displayed shorter wave V latencies and interwave intervals relative to AGA infants. These differences, however, disappeared by term age whereas the contrasts in laterality persisted. Increasing the rate of stimulation reduced wave I amplitude irrespective of conceptional age and increased wave V amplitude prior to term. An increase in wave V latency was more pronounced at the higher rate on the left than the right. There was no interaction between rate and appropriateness for gestational age, although SGA infants had shorter wave V and interwave latencies. Our data indicate a slight but significant right ear advantage in the processing of auditory signals. Gender differences were apparent as well. While research on adults and older children have reported similar findings, no other studies to date have observed these results in neonates. The present work also lends support to the view that accelerated neurological development occurs in growth-retarded infants.

An improved procedure for assessing ABR latency in young subjects based on a new normative data set

Auditory brainstem response (ABR) latencies in normal young and very young subjects are longer than in mature subjects. Use of adult norms in the assessment of young subjects may therefore result in the erroneous reporting of abnormalities in subjects who are in no way impaired. In this study a new normative data set was established by measuring ABR absolute and interpeak latencies in 374 subjects in different age groups with normal ABR and no risk factor for hearing impairment or neurological abnormality. Double exponential functions were fitted to a number of latency measures derived from the data and from those functions a table of correction values was computed. The variability in the measurements of the children is greater than that of the adults. Procedures are proposed which enable the assessment of abnormality of ABR latencies to be made for all subjects regardless of age.

Auditory brainstem response to bone-conducted clicks in adults and infants with normal hearing and conductive hearing loss

Knowledge concerning auditory brainstem response (ABR) by bone conduction (BC) is limited, and occasionally controversial. The present study was aimed at further elaboration of this issue. The research population consisted of 107 subjects. Four groups were investigated: group 1, normal-hearing adults aged 20-37 years; group 2, 10 children aged 5.6-8.4 years, with confirmed middle ear effusion (MEE); groups 3 and 4, 22 infants, matched by pairs, aged 5-18 months, 11 with normal otoscopy and 11 with suspected MEE. Comparison between ABR by AC and BC for all four groups is discussed. We observed that the AC-ABR threshold of group 2 was statistically significantly elevated compared to group 1. The same tendency was observed for group 4 compared to group 3. In AC ABR, the mean latency of wave V was significantly prolonged, compared to that of BC ABR in children with confirmed MEE, and infants with suspected MEE. We strongly suggest that by combining AC and BC ABR, more information concerning cochlear reserve status can be obtained in infants and young children who are difficult to test, or wherever a behavioral audiogram cannot be achieved.