Gender differences in electrical pain threshold responses to transcutaneous electrical nerve stimulation (TENS).

Gender differences in pain perception have been frequently discussed, but the documented gender-related pain-alleviating effects of non-pharmacological methods are sparse. In this study we aimed to investigate changes in electrical sensory thresholds and electrical pain thresholds, in response to high frequency transcutaneous electrical nerve stimulation, TENS, for 20 min in healthy women (n=29) and men (n=29). The thresholds were assessed pre-, during-, and post-TENS. The pattern of change in thresholds was evaluated with a rank-based statistical method regarding the level of systematic change, expressed as relative position (RP) and additional individual changes, expressed as relative rank variance (RV), with its 95% confidence intervals. Equal levels of systematic changes towards increased electrical sensory thresholds were seen in women and men post-TENS (RP, 0.35; 95% CI, 0.07, 0.63, and RP, 0.36; 95% CI, 0.17, 0.53, respectively). At the same point of time, systematic changes towards increased electrical pain thresholds were only seen in women (RP, 0.43; 95% CI, 0.27, 0.60), while they were unchanged in men (RP, -0.01; 95% CI, -0.13, 0.10). Significant additional individual variations were found in the women's responses of assessed electrical sensory and pain thresholds but not in the men's. It is concluded that both women and men responded with a significant increase of the electrical sensory threshold to high frequency TENS, but only women responded with increase of the electrical pain thresholds. The individual variation of the responses was greater in the women than in the men.