Subcortical somatosensory evoked potentials after median nerve stimulation in children.

We report our normative data of subcortical somatosensory evoked potentials (SEPs) after median nerve stimulation from a group of 55 children 4-15 years of age and 18 young adults 18-29 years of age. We recorded near-field potentials from the brachial plexus, the cervical cord and the somatosensory cortex. The far-field potentials P13, P14 and N18 from the brainstem were recorded from the scalp electrodes, when a non-cephalic reference at the contralateral Erb's point or an ear reference was used. The N9 (brachial plexus), N13a (dorsal horn), P13 (caudal medulla oblongata), N18 (medulla oblongata) and N20 (somatosensory cortex) were present in all subjects. The N13b (dorsal column near the foramen magnum or cuneate nucleus) was observed in all children and in 16 adults, P14 (medial lemniscus) in 52 children and 17 adults. The median nerve SEPs provide reliable information about the function of the somatosensory pathway from the upper limb. The subcortical median nerve SEPs should be particularly useful to detect lesions of the upper cervical cord and the cervicomedullary junction. The subcortical SEPs remain unchanged during sleep and facilitate reliable SEP recordings, when sedation is necessary in infants and children.