A study of the maturation of the somatosensory pathway by evoked potentials

We investigated the somatosensory evoked potentials (SSEPs) in 62 healthy children, ten days to twelve years old. Our control group consisted of ten healthy adults, sixteen to thirty-six years old. The stimulus was applied at the median nerve at the wrist and the cerebral SSEPs were recorded by electrodes placed on the contralateral parietal scalp region, while for the cervical SSEP recording the electrodes were placed over the skin at the C6-C7 vertebral region. The reference electrode was placed at the FZ according to the 10-20 system. Our study revealed a significant change in the early components of the SSEPs (NI and PI) between groups of different ages. The latency and duration of the NI wave form and the latency of PI were inversely correlated with age. These changes in the early components of the SSEPs are most likely due to the gradual maturation of the afferent nervous system with age. From the difference in latencies between the peak of NI and the cervical SSEP we were able to calculate the sensory conduction time in the central nervous system and found a progressive decrease in relation to the increase of age. This is most likely due to the development of postnatal myelination of the sensory fibres of the central somatosensory pathway.