An investigation into the effect of electrode placement of transcutaneous electrical nerve stimulation (TENS) on experimentally induced ischemic pain in healthy human participants

Introduction: It is claimed that transcutaneous electrical nerve stimulation (TENS) operates via a segmental mechanism by reducing ongoing transmission and sensitization of nociceptive dorsal horn neurons. Hence, TENS electrodes are usually placed at the site of pain. Objective: This study compared TENS administered at the site of experimentally induced ischemic pain (ipsilateral forearm) with TENS administered at a location not related to pain (contralateral lower leg). Methods: Ten healthy, pain free volunteers took part in a crossover study during which ischemic pain was induced in the nondominant arm using a modified version of submaximal effort tourniquet technique. Pain intensity was taken at 1-minute interval/s for 5 minutes while receiving TENS either at the ipsilateral arm or contralateral leg. Results: There were no statistically significant differences in pain intensity or McGill Pain Questionnaire ratings between TENS given at the arm compared with the leg. Discussion: Taken at face value, the findings suggest that TENS effects were nonspecific and that electrode location does not affect outcome. However, this study should be seen as a call for further research rather than a definitive conclusion.