PERIPHERAL NERVE NEUROSTIMULATION EVOKES ANALGESIC AND ANTINOCICEPTIVE EFFECTS IN A HUMAN EXPERIMENTAL MODEL.

Electrical peripheral neurostimulation (PNS) is reported to be an effective pain treatment. Due to lacking objective proof of antinociceptive effects, this experimental study addressed the effect of PNS on nociception and pain by electrophysiological and psychophysical means in an advanced human experimental model. Thirty-nine experiments were performed in 23 healthy volunteers (three experimental groups: ipsi-, contralateral, no PNS; n=13). Conditioning PNS (100 Hz, 200 ms) of left (ipsi-) or right (contralateral) superficial radial nerve trunk evoked tingling paresthesia on the hand dorsum. Local cutaneous anesthesia at PNS site provided for selective nerve trunk stimulation. Late vertex potentials (LEP) evoked by painful laser heat stimulation in the innervation territory of the left radial nerve were recorded together with laser pain ratings and mechanical detection thresholds at the same site before, during and after PNS or no conditioning. LEP amplitude decreased independent of PNS side (p<0.001). Only with ipsilateral PNS, N2 latency increased (p<0.01), pain perception (p<0.05) and mechanical perception (p<0.001) decreased transiently. Divergent results document locally specific and unspecific effects of PNS on nociception and pain in an advanced experimental model.