A novel method of eliciting pain-related potentials by transcutaneous electrical stimulation

Background.-Electrophysiological techniques such as laser and contact heat evoked pain-related potentials are very useful for studying trigeminal and somatic pain transmission in humans. These methods are, however, partly invasive, expensive, and therefore not available for broad clinical use. We recently proposed a novel technique of noninvasive transcutaneous electrical stimulation. Objective.-To elicit pain-related evoked potentials (PREP) by using a concentric planar electrode and demonstrate their nociceptive specificity. Methods.-We registered PREP following stimulation of the forehead and hand in 14 healthy volunteers. Latencies, peak-to-peak amplitudes, and conduction velocities of nociceptive fibers have been estimated. Effects of temporal and spatial summation and of cutaneous anesthesia were evaluated. Results.-Stimulation with the concentric planar electrode produced pinprick-like painful sensation. Cutaneous anesthesia led to abolishment of PREP responses. Estimated mean conduction velocity was 11.61 +/- 5.12 m/s, which corresponded well with conduction via A-delta fibers. Spatial,as well as temporal summation resulted in a parallel increase of perceived pain intensity and PREP amplitudes. Conclusion.-The technique is noninvasive, affordable, and easy to perform and allows quantitative assessment of human nociceptive pathways.