Effects of age, gender, and stimulus side on scalp topography of somatosensory evoked potentials following median nerve stimulation

This is the first study to evaluate the effects of age, gender, and stimulus side on scalp topography of somatosensory evoked potentials (SEPs) following stimulation of the median nerve by using computerized bit-mapped color images. Seventy-four normal subjects whose ages ranged from 7 to 88 years were studied, and Student's t test was performed on averaged mean maps and their standard deviations of each recognizable component by using the significance probability mapping method. Topographic maps of most components in aged subjects were significantly different from those in young subjects, mainly because of higher amplitudes of the components in the aged group. This difference was particularly significant for later components with the peak latencies of longer than 40 ms. Gender and stimulus side caused no significant differences in amplitude and topography of the components. Therefore, for clinical application of topographic maps of median nerve SEPs, a difference of gender and stimulus side could be disregarded, but it is necessary to consider the age effect.