Article
Peripheral nerve stimulation inhibits nociceptive processing in man
Periphere Nervenstimulation hemmt die nozizeptive Signalverarbeitung beim Menschen
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Published: | April 23, 2004 |
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Outline
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Objective
The gate control theory suggests the inhibition of pain processing by the activation of thick-myelinated, non-nociceptive peripheral nerve fibers. Therefore, electric peripheral nerve stimulation (PNS) was introduced into neuromodulatory pain therapy as a validation of this concept. The rationale of this study was to evaluate the effect of innocuous PNS on nociceptive processing in healthy volunteers.
Methods
Cortical potentials were evoked by painful heat stimuli applied by a thulium-YAG laser to the left dorsal hand in 14 healthy subjects. The laser evoked potentials (LEP) and the subjective ratings were recorded in three blocks (T0, T1, T2) of 50 laser pulses each with 15 min intervals. The PNS was performed by transcutaneous electric stimulation of the left superficial radial nerve (200 µs, 30 Hz) for 23 min eliciting tingling sensations on the dorsal hand. The volunteers participated in two sessions: In the PNS session the conditioning PNS started after T0 and lasted until the end of T1 whereas no PNS was applied in the control session.
Results
Both the laser evoked cortical potentials and the subjective ratings significantly changed during PNS. In the PNS session the T0 N2-P2 amplitude of 29.4±3.3 µV (mean±sem) reduced to 20.2±2.3 µV during PNS (T1) (p<0.001). The N2 latency increased from 194.5±7.5 ms (T0) to 207.3±9.4 ms under PNS (p<0.05). The subjective ratings decreased during PNS (T1) to 89.5±3.1% as compared to T0 (p<0.01). Subjective ratings, LEP latencies and amplitudes did not differ significantly among the three blocks in the control session.
Conclusions
These experiments showed indeed a significant reduction of laser evoked cortical potentials and subjective pain perception by innocuous PNS in healthy volunteers. So far, this is the only study assessing the antinociceptive effect of PNS objectively in man.