Maturational changes in the brainstem auditory evoked response in very low birth weight infants

Abstract

Background: Brainstem auditory evoked response (BAER) is a sensitive test of the functional integrity of the auditory pathway. Latencies and amplitudes of measured waveforms reflect maturation of this brainstem pathway and may allow a prediction for neurological outcome. Patients and methods: BAER were measured prospectively in preterm infants with a birthweight less than 1500 g at 3 to 4 day following birth and during treatment on neonatal intensive care unit (NICU) every two weeks. Pre- and postnatal risk factors and frequency of apnea were evaluated. Outcome was scored after 1 year corrected age by neurological examination. Results: There were no significant differences in latencies of waves between 5 children with severe asphyxia and/or IVH resulting in major neurological handicaps after 1 year. However, two of these children have bilateral abnormalities. The slope of decay of wave latencies decreased between 30 and 32 weeks gestational age, while the number of registrated apnea increased. In follow up investigations during treatment on NICU there was a decrease in interpeak latencies wave V to wave III from 24/25 weeks gestational age to term infants and increase in amplitudes. Conclusion: Early performed BAER alone is not a good predictor for neurological outcome of preterm infants because of great interindividual varibility of normal neonates and the anatomical site of cerebral lesions. The method contributes information on the brainstem maturation and may also reflect the different maturational stages of the respiratory system.