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Auditory brain stem responses in preterm infants: evidence of peripheral maturity
D M Schwartz1, R E Pratt, J A Schwartz
1Department of Otorhinolaryngology, University of Pennsylvania Medical Center, Philadelphia.
Insights
Peripheral auditory systems in preterm infants are mature, as shown by auditory brain stem response (ABR) testing. Infant ABR wave I measures were comparable to adults, indicating robust peripheral auditory function.
Area of Science:
- Neuroscience
- Audiology
- Developmental Biology
Background:
- Auditory maturation involves both peripheral (cochlea, auditory nerve) and central (brainstem) components.
- Auditory brainstem response (ABR) is a key tool for assessing auditory pathway function.
- Previous studies suggested delayed maturation in infants' auditory pathways.
Purpose of the Study:
- To investigate peripheral and central auditory system maturation in preterm infants using ABR.
- To compare ABR findings in preterm infants with those in adults.
Main Methods:
- Auditory brainstem responses were recorded in preterm infants and adults.
- Rarefaction and condensation click stimuli were delivered via insert earphones.
- Analysis focused on wave I, III, and V latencies, amplitudes, and variability.
Main Results:
- Infant ABRs showed a triphasic waveform preceding wave I, similar to adult electrocochleography.
- Wave I latency, amplitude, and variability in infants were equivalent to adult values.
- Latencies for waves III and V differed between infants and adults as expected.
Conclusions:
- The findings strongly support peripheral auditory electromaturity in preterm infants.
- ABR wave I consistency in infants challenges prior attributions of delayed maturation to cochlear or neural immaturity.
Abstract:
This study explored further the relationship between peripheral and central auditory maturation on the basis of the auditory brain stem response. Auditory brain stem responses were recorded in preterm infants and adults to rarefaction and condensation click stimuli transduced through insert Tubephones. Infant recordings presented a triphasic waveform preceding wave I similar to that of the cochlear receptor potentials seen with adults during electrocochleography. Wave I latency and amplitude were found to be equivalent to those of adult subjects. Moreover, neither latency nor amplitude variability among infant wave I responses was found to be any greater than adults. Latencies of waves III and V, however, exhibited the expected differences relative to the adult comparison group. When the indirect evidence of cochlear receptor potentials in the infant are viewed adjacent to the observations that their ABR wave I latency, amplitude, and variability were entirely consistent with those of young adults, the data lend strong support for peripheral auditory electromaturity. These data are discussed relative to previously published reports of prolonged wave I latency in the infant which was attributed either to middle ear effects or immaturity of the cochlea and first order VIIIth nerve neurons.