Somatosensory evoked potentials in very preterm infants

Objective: Cross-sectional and longitudinal reference values of cortical N-1 peak latency of the median nerve SEP in very preterm infants. Methods: In infants in a placebo control group within an L-thyroxine supplementation trial, born at less than 30 weeks' gestation, cortical N-1 peak latency was measured at 2 weeks, at term and at 6 months corrected age. Cross-sectional N-1 latency values obtained in 50 infants and complete series of longitudinal values obtained in 15 infants were analyzed in relation to postmenstrual age (PMA). Results: Mean N-1 latency decreased from 66 ms at 2 weeks to 38 ms at term and 20 ms at 6 months corrected age. Possible confounding factors did not have any significant effect on N-1 latency at 2 weeks or at term age except cranial ultrasound abnormalities at 2 weeks of age. Conclusions: Longitudinal N-1 latency values were consistent with cross-sectional N-1 latency values. The observed N-1 latency at term and at 6 months corrected age suggest that extrauterine maturation of the somatosensory pathway in infants born at less than 30 weeks' gestation is delayed by extrauterine life. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.