Somatosensory evoked potentials in full-term neonates with perinatal asphyxia.

Objective: To explore the capacity of somatosensory evoked potentials (SEP) to assess maturation processes in the development of the nervous system, and the characteristics of SEP in healthy full-term infants and full-term newborns with perinatal asphyxia and their follow up until the age of 14 months.

Materials And Methods: SEP were studied in 21 healthy full-term infants and 38 full-term newborns with perinatal asphyxia. The children with asphyxia were studied longitudinally until they were 14 months old. To assess the SEP we measured the latency of the P15, N20 and P25 components, the amplitude ratio N20/P25 and inter-peak intervals P15-N20 and N20-P25.

Results: The component that was most typically always found in the SEP recordings of both healthy infants and those with perinatal asphyxia was N20. The mean latency values of P15, N20 and P25 were higher in the children with perinatal asphyxia (p < 0.001). The SEP amplitude was highly variable (CoV% = 76.6%). The latencies became shorter with age in asphyxia patients aged 0 to 14 months, the shortening being the greatest in the first trimester, while they showed no statistically significant differences in infants aged 6 to 12 months.

Conclusions: SEPs in the neonatal period differ considerably from those of adults and older children in the morphology and longer potential latency, which can be accounted for by the incomplete myelination of nerve fibers. The changes in SEP latency in patients with HIE stages I and II follow the same pattern found in healthy children--latency became shorter with increasing age, which was most pronounced in the first 3 months. SEP latency was found to be correlated with height and age. No differences were found in the latency of potentials between healthy infants and infants with brain hemorrhage. Recording SEP is a sensitive method to assess the CNS in children with perinatal asphyxia and to monitor the maturation of the somatosensory pathway.