[Somatosensory evoked potentials in children and adolescents during stimulation of the median nerve. Anthropological measurements: Part I].

Somatosensory evoked potentials (SEP) are responses which appear under the influence of sensory stimuli, producing a series of bioelectric changes in the peripheral and central nervous system. Particular components of SEP are recorded from the stimulation point-at the wrist--of the examined median nerve through the brachial plexus, spinal cord and subcortical structures to gyrus postcentralis in the brain. The source of N 20 wave is found in the primary sensory cortex, while P 25 is the response from the somatosensory region of the cerebral cortex in the parietal lobe, in the region responsible for the upper limb. N9 deflection is generated by the stimulation wave, going along the brachial plexus (Erb's point). 50 children and adolescents at the age of 8-16 were examined. In the analysis of the obtained results the influence of sex, age, height, the length of upper limbs, head circumference and temperature of the examined patients' skin was taken into consideration. SEP recording was performed with the use of Multiliner equipment, (Toennies, Germany) according to the recommendation of the International Federation of Clinical Neurophysiology. The responses obtained during the stimulation of median nerves were recorded with the use of surface electrodes located at the head according to 10-20 system in C'3 and C'4 points and from the active electrode EP situated at Erb's point above the brachial plexus. Latencies and amplitude, component of short latency (N20, P25, N9) time differences of their appearance and the speed of nerve impulse conduction along stimulated fibres were analysed. There were significant relations found between latency of N9 and N20 waves and age, height and the length of limbs in examined patients but there were no relations found between P 25 appearance and the elements mentioned above. It was stated that the head circumference did not influence time of cortical waves appearance. Moreover, it was not found that growth of skin temperature within the range of 30-36 degrees C significantly influenced the acceleration of nerve impulse conduction along stimulated fibres. It was proved that SEP is a precise and non-invasive method which may be applied in children and adolescents. Interpretation of the obtained results requires consideration of anthropological parameters that change during the developmental age.