Cortical Neurophysiological Modification after Peripheral Neuronal Sensitization

Comparison of the effective intensity of transcutaneous electrical nerve stimulation contralateral to a pain site for analgesia

[Purpose] This study aimed to compare the effectiveness of transcutaneous electrical nerve stimulation contralateral to the pain site for analgesia to identify the effective stimulation intensity. [Participants and Methods] Ten healthy adult females were recruited for the study. The same heat stimulation was applied to the left wrist joint of each participant to induce pain, serving as the control. Transcutaneous electrical nerve stimulation was then randomly administered to the right wrist, corresponding to the same dermatome contralateral to the painful site, at the intensities of comfortable stimulation, pain threshold, and maximum pain. The effect of transcutaneous electrical nerve stimulation was assessed using a Visual Analogue Scale and by analysis of heart rate variability. [Results] The Visual Analogue Scale score was significantly lower after stimulation with the maximum pain intensity than that for control, and there were no significant differences among the intensities of comfortable stimulation, pain threshold, and maximum pain. No significant differences were found among the groups in terms of high and low-to-high frequency components. [Conclusion] Transcutaneous electrical nerve stimulation at the maximum pain intensity to the dermatome area contralateral to that of the dorsal pain site of the left wrist was considered effective.

Comparison of the pain-relieving effects of transcutaneous electrical nerve stimulation applied at the same dermatome levels as the site of pain in the wrist joint

[Purpose] The purpose of this study was to develop a proposal for an effective interventional option for therapeutic stimulation sites by comparing the pain-relieving effect of transcutaneous electrical nerve stimulation (TENS) applied to the same dermatome level of the contralateral sites of the dorsal wrist joint with the pain or the neck, or both sites simultaneously. [Subjects and Methods] A control was first established by triggering pain in the left dorsal wrist joints of adult females by using heat stimulation. Three interventions were then performed, comprising the TENS to the contralateral wrist joint (CW) and to the neck (N) at the same dermatome level as the site of pain, and the TENS to both CW and N simultaneously (CWN). Levels of pain and cerebral blood flow were also measured. [Results] The pain levels of three interventions were found to be significantly decreased compared with the control; however, no significant differences in the levels of pain were seen between any combinations of three interventions. Furthermore, no significant differences were seen between any interventions in terms of cerebral blood flow. [Conclusion] The results suggest that in order for TENS to be effective, it is necessary to make effective use of the dermatome.