Short latency somatosensory-evoked potentials in children--Part 1. Normative data.

Spinal, subcortical, and short latency cortical somatosensory-evoked potentials (SEPs) following electrical stimulation of the median or tibial nerve were studied in 100 children aged 4 weeks to 13 years. Standard neurophysiological methods of recording surface SEPs were used in sedated and nonsedated children. The morphology of the SEPs was similar to that obtained in adults; however, the initial components of the cortical SEP following median nerve stimulation did show maturational changes in both interpeak latencies and morphology. The negative peak latencies recorded over Erb's point (N9 equivalent) and the second cervical vertebra (N13 equivalent) following median nerve stimulation, and over the lumbothoracic junction (N14 equivalent) following tibial nerve stimulation were directly related to patient age and limb length. There was no correlation between age and the latencies of either the initial negativity (N18 equivalent) or the initial positivity (P28 equivalent) of the cortical SEPs following respective median and tibial nerve stimulation. The central somatosensory conduction time decreased slowly during the first decade and attained adult values after 8 years of age. The lumbar spine to scalp transit time showed no direct relationship to age. Comparisons of SEPs recorded in the same subject when awake and under general anesthesia showed that the latencies of the subcortical, spinal, and N1-P1 complex of the cortical SEP are identical; however, the later components of the cortical SEP vary both in latency and amplitude with anesthesia. This study represents normative data against which SEP in children with disorders of the central nervous system may be compared.