Artikel
Changes in peripheral and central components of the brainstem auditory evoked response in newborn lambs after perinatal asphyxia
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Veröffentlicht: | 19. April 2011 |
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Introduction: Perinatal asphyxia occurs in 1–6 per 1,000 full-term births and is considered as a major risk for auditory impairment in childhoood. Limited functional information is available about the effects of perinatal asphyxia to the auditory pathways. Because of the similarities between humans and sheeps in the course of neural development, a sheep model was used in our experiment.
Methods: Time-mated ewes were randomly assigned to an asphyxia or sham group. Gestation was termed by elective caesarean section (gestational age 129–136 days, term 145 days). The asphyxia group (n=12) received an umbilical cord occlusion directly before delivery and were compared whith a sham treated group (n=11). After delivery serially ABR were recorded during 8 hours.
Results: Hearing threshold in the first time interval after birth was significantly higher in the asphyxia group compared to the control group (mean 34.2±1.4 vs 28.6±1.8) (p=0.02). In the 3th interval the amplitudes of wave II and III had the tendancy to be lower then the control group (wave II mean 0.15±0.02 vs 0.25±0.04 (p=0.06), wave III 0.56±0.04 vs 0.76±0.07 p=0.03).
Discussion: The event of perinatal asphyxia by umbilical cord occlusion resulted in a temporary elevation of the hearing threshold in the preterm lamb. The severity of the hypoxic event, its effect to circulatory disturbances and the rate of acidosis will be of great importance to the extend of central and peripheral damage and its potential to recover. In the third interval the amplitude of early and late waveform peaks was reduced. Our research highlights the early phase of the hypoxic effect of perinatal asphyxia to the auditory pathways which will help in the understanding of the detailed process of hearing impairment in infants.