Electrical stimulation in the measurement of cutaneous sensibility

A portable constant current electrical stimulator with bipolar felt disk electrodes was developed for quantitative assessment of cutaneous sensibility. The new method was used in the measurement of thresholds for perception and pain in healthy volunteers. The mean values of the threshold for perception in different areas of the body varied between 1.0 and 2.0 mA (S.D. +/- 0.2-0.6 mA) and those of the threshold for pain between 2.5 and 4.3 mA (S.D. +/- 0.5-1.7 mA). There was no difference between the left and the right side. The interindividual range of the perception threshold varied from 0.4 to 3.0 mA and that of the pain threshold from 1.2 to 6.0 mA. Within a limited area of the body the reproducibility of the measurements was high both for the thresholds for perception and for pain. Anterolateral cordotomy caused a marked rise in the threshold for pain in the analgesic area of the body, whereas the threshold for perception did not change. It is hypothesized that the threshold for perception reflects an activation of A beta fibers and the threshold for pain an activation of A delta fibers. The new method is considered to be valuable in clinical neurology and neurosurgery.