Somatosensory evoked potentials to posterior tibial nerve stimulation in children.

The somatosensory evoked potentials (SEPs) to stimulation of the tibial nerve were studied in 88 children ranging in age from 1 day to 16 years. SEPs were not evidenced in 10 out of 44 infants less than 1 year old. In others it was a major positive wave (P) with a variable topographic distribution on the midline. The onset and peak latencies of this P were highly variable in different subjects of the same age or body-size, and in the same subject with the active electrode placed in different locations. The lowest values for latency were in subjects about 3 years old. The ascending time of P was the only parameter strictly correlated with age. The results are compared with SEPs to upper limb stimulation, which are constant and more reliable. These results indicate: that the maturation of the peripheral somatosensory pathway proceeds at a faster rate than that of the central somatosensory pathway; that the maturation of the somatosensory pathway of the upper limb precedes that of the lower limb; and that the ascending time of P is a good index of thalamo-cortical maturation. The clinical utility of these SEPs in pediatrics is discussed.