The effects of stimulus rates on the amplitude of median nerve somatosensory evoked potentials: the developmental change

We examined the effects of stimulus rates on the somatosensory evoked poten tial (SEP) amplitudes following median nerve stimulation at the wrist in 42 children. We divided these subjects into five groups according to their ag e (0-6 months, 7-12 months, 1-3 years, 4-6 years and more than 7 years) and measured the peak-to-peak amplitude of every component (N9, P10, N11, P13/ 14, N18, N20, P23, N30) at stimulus rates of 1.0, 3.5 and 5.5 Hz. From N9 t o N18, there was no significant change in amplitude nor latency with stimul us rate change in all groups. The amplitude attenuation was found at the N2 0 and N30 peaks in the young group (0 months to 3 years) and at P23 in all groups with an increasing stimulus rate. The attenuation rate of P23 amplit ude was influenced by the age of subjects, being greater in younger groups and greatest in the youngest group (0-6 months). The differences of amplitu de attenuation rate between this group and the rest were statistically sign ificant. The results of this study indicate that the amplitudes of the cort ical components of SEP in children are greatly influenced by the stimulus r ate. Thus when we discuss the amplitude of cortical waves in childhood, we should also pay attention to the stimulus rates. (C) 1999 Elsevier Science B.V. All rights reserved.