Extrauterine maturation of somatosensory pathways in preterm infants: a somatosensory evoked potential study

To evaluate the reliability of somatosensory evoked potential (SEP) recordings in preterm infants to monitor the intra-uterine and extrauterine maturation of somatosensory pathways.

We performed SEPs in 35 neurologically normal preterm babies (range 23-35 weeks gestational age--GA). Twenty-four of all infants were evaluated after the first 2 weeks of life, at a minimum post-menstrual age (PMA) of 31 weeks, and 31 at term corrected age. In 15 infants we obtained longitudinal recordings at both epochs. Cross-sectional and longitudinal values of first cortical potential (N1) were analyzed in relation of PMA and matched with those measured in a group of 11 fullterm babies.

Reproducible cortical SEPs were found in 92% of preterm babies at first recording, and in all 31 neonates at follow-up. A significant inverse correlation between the latency values of N1 and PMA at the time of first recording was observed, showing that latencies of these components rapidly decrease with increasing PMA. Regression analysis showed no significant effect on N1 latency at term correct age in dependence of GA, suggesting that extrauterine life does not affect maturation of somatosensory pathways. Interestingly, the occurrence of idiopathic respiratory distress (RDS) during clinical course after birth correlated with a delayed N1 latency at term corrected age.

Extrauterine life does not affect maturation of somatosensory pathways in preterms without neurological deficit. Finally, the mild negative influence of RDS on maturational changes was evident.

SEPs could be considered a useful tool for a non-invasive assessment of somatosensory pathways integrity in preterm infants.