Effects of age, gender, and stimulus side on the scalp topography of somatosensory evoked potentials following posterior tibial nerve stimulation.

This is the first thorough study to evaluate the effects of age, gender, and stimulus side on the scalp topographies of somatosensory evoked potentials (SEPs) following stimulation of the posterior tibial nerve by using computerized bit-mapped color images and the significance probability mapping method. Seventy-four normal subjects whose ages ranged from 7 to 88 years were studied. Topographic mappings 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. However, scalp distribution of each component did not show a large difference among different age groups. There was a tendency that amplitudes in women were larger than those in men, and the gender differences of some components were significantly larger for some age groups. Stimulus side and handedness caused no significant difference in amplitudes and topographies of the components. These results were very similar to our previous results of the scalp topographies of SEPs following median nerve stimulation.