Auditory event-related potentials and cognitive outcome after very preterm birth
Children born before 32 gestational weeks have a high incidence of neuropsychological deficits. The structural and functional correlates of such impairments in preterm infants are incompletely understood, and early diagnostic tools are needed, but still lacking. Auditory event-related potentials (AERPs) are neurophysiological measures of cortical sound detection, encoding, discrimination, and attentional processes. Abnormal AERPs have been associated with cognitive and behavioral problems. To date, there has been very little research into AERP in preterm infants. Therefore, our aim was to investigate if AERPs in infants and children born very preterm correlate with cognitive outcome, and whether AERPs are related to findings on magnetic resonance imaging (MRI) at term. We investigated 70 children at 4-5 years of age who had been born very preterm, using AERPs and psychological testing, and compared them with more mature preterm and full-term children of the same age. Furthermore, we performed AERPs and MRI in another 42 very preterm infants at term, and these infants had a follow-up testing at 2 years of age. AERPs at preschool age in children born very preterm showed abnormalities in comparison with more maturely born children. Similar abnormalities have been reported in full-term children with cognitive and behavioral problems (especially smaller amplitudes of early AERP deflections). Within the very preterm group, faster early sound processing was associated with better psychological test results, and sound differentiation was different between children with normal and abnormal test results. We showed that immaturity at birth, neonatal morbidity, and neonatal brain damage had an impact on different aspects of auditory processing, and that this impact still was present at 5 years of age. In the infants investigated at term age, we showed that later sound processing as well as sound differentiation has a high correlation with both cognitive and neurological outcome. Neonatal morbidity rather than prematurity itself had a strong impact on sound differentiation. AERPs showed stronger associations with outcome than brain volumes. We conclude that AERPs are promising as a prognostic tool for outcome in very preterm infants. They can add considerably to established anatomical methods such as MRI. However, more research is needed before AERPs can be applicable in clinical praxis.
Pediatrics, Preterm, Event-related potentials, Mismatch negativity, Magnetic resonance imaging, developmental outcome
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