Somatosensory cortical and dermatome evoked potentials: a study conducted on 60 normal subjects. Results and their correlation relative to height and age.

The somatosensory cerebral evoked potentials of the median and tibial nerves (N 20, P 38), as well as dermatome evoked potentials by stimulation of specific dermatomes corresponding to the roots C5, C6, C7, C8-T1, L3, L4, L5 and S1, were recorded on the scalps of 73 normal subjects. The height and age of each subject were noted. Of the 73 subjects studied, 60 were withheld for the protocol. The technique and constants used for recording are explained, as well as the results obtained. A statistical analysis was undertaken, using parametric and non-parametric methods. The latter enabled us to determine the averages, standard deviation, median and percentile for each of the latencies. A study by correlation allows for a comparison between the left and the right sides, and between the various dermatomes. For median and tibial nerves and for each dermatome latency values are correlated to subjects' height and age. Thus, it is possible to show the absence of correlation between the median nerve, the dermatomes of upper limbs with age and height, whereas there exists a perfect correlation with age and height for the tibial nerves and the dermatomes of lower limbs. All normal results adjusted to height and age are given.