In this clinical trial of Japanese-style and sham acupuncture for chronic pelvic pain, subjects had elevated Hibiki-7 measures at the Liver, Spleen, and Kidney Jing-Well points at baseline. These abnormal values decreased over time with the active, but not sham, acupuncture treatments. These changes were reflected in the dispersion and asymmetry electrodermal measures. In univariable analyses, electrodermal imbalance measures were associated with pelvic pain and quality of life measures, but with multivariable modeling, the associations with the clinical outcomes were narrowed to designated treatment and to one of two asymmetry variables: yin–yang or right–left asymmetry. Other than a single meridian (left Kidney or right Stomach), electrodermal measures were not associated with IL-6 or TNF-α levels.
The clinical significance of the increased Hibiki values at the Liver, Spleen, and Kidney points is unclear. These Jing-Well points and their associated meridians are located on the inner aspect of the lower extremity. Consequently, the results can be interpreted as a technical effect stemming from the placement of the electrodes on the inner toes or the current trajectory from the probe tip (toes) to the passive electrode (hands). However, the temporal reductions observed in these Hibiki values with the active and not sham interventions argue for a physiologic rationale that is not yet elaborated.
The idea that certain diseases or conditions are attached to particular electrodermal patterns is not new and is used to advocate for the clinical utility of these electrodermal devices. For instance, in 1973, Bergsmann described statistically different voltage-current measurements at right Liver 9 in patients with “liver disturbances” compared to measurements at adjacent skin areas, the left Liver 9, or at right Liver 9 in healthy controls.24
Saku also described statistically significant differences in electrical impedance at auricular Heart points in patients with acute or old myocardial infarctions compared to healthy controls.25
Other studies have similarly reported distinct electrodermal patterns in certain medical conditions, but, like these two studies, were limited by the lack of objective confirmation for the disease.26–35
Although patients in our study were laparoscopically diagnosed with endometriosis, the lack of a healthy or nonhealthy control precludes any reliable assessment of whether our observed electrodermal patterns are specific to women with endometriosis and chronic pelvic pain.
The decrease in asymmetry and dispersion seen with active acupuncture and not sham treatments is revealing and is significant for a number of reasons. These electrodermal measures are fundamentally rooted in Eastern medicine principles and aim to assess the activities of a theoretical meridian system. To observe quantitative changes in these measures with acupuncture compared to sham treatments suggests that there is a physiologic effect of acupuncture that likely goes beyond placebo. These effects are seen over a span of weeks and appear to peak and stabilize at 4 weeks (). Furthermore, these documented changes are consistent with the schema espoused by acupuncture theory, namely, that acupuncture restores balance and eliminates asymmetries.4
To see these intentional effects result from interventions performed on sites far from the Jing-Well points is intriguing and prompts further questions about the biological mechanisms of acupuncture. Nevertheless, the existence of a measure that is both quantitative and consistent with acupuncture theory may be helpful for basic research and needs further evaluation before any conclusions can be drawn.
Whether these electrodermal measures translate into meaningful clinical assessments, on the other hand, is a different question. Based on the graphical representation of electrodermal measures over time, clinical “responders” had a negative trend in both dispersion and asymmetry measures while “non-responders” had a positive trend (except for yin–yang asymmetry). These differences, however, were not as robust as the ones seen between acupuncture and sham groups and could be interpreted as being confounded by treatment designation. In other words, “responders” are more likely to be designated to the acupuncture group than “nonresponders” and thus demonstrate reductions in imbalance measures. The multivariable analyses, however, show that asymmetry measures—specifically, the left–right and yin–yang variables—are independently associated with clinical outcomes even after accounting for treatment effects. In Pediatric QOL, yin–yang was the only significant variable. Because the general estimating equations model accounts for repeated measures in study participants, the timing of the test (at baseline, 4 weeks, and 8 weeks), the quantitative level of both clinical outcome and the Hibiki-7 measures, and multiple covariates, it is better suited to capture significant associations than a dichotomized analysis that arbitrarily chooses a single cutoff at a particular time-point (30% improvement at 8 weeks).
Based on the univariable analyses, pelvic pain is more commonly associated with electrodermal measures than the other clinical outcome measures. This may stem from components within the various Quality of Life assessments that have indirect relevance to the physiologic state of the body. For instance, the control/powerlessness, self-image, and social support subscales within the Endometriosis HRQOL-30 or the social health and school participation subscales within the Pediatric QOL may be poorly linked with electrodermal measures and thus contribute to fewer univariable associations. However, the fact that these QOL scores were significantly associated with general imbalance variables and not with specific meridian measures denotes the specificity of these imbalance variables (dispersion and asymmetry) to more global/qualitative assessments of health. Pain level can also theoretically reflect global health because there are psychologic and emotional components to it as well. This link between the general imbalance variables and global health is further supported by the lack of statistical association between any of the imbalance measures and inflammatory cytokine levels (a more specific outcome measure). The electrodermal measures of imbalance may play a surrogate role for qualitative measures, but additional studies are needed to further assess the clinical validity of these electrodermal measures and the relative importance of the various imbalance measures.
This study has a number of limitations. First, with 14 participants, it has limited sample size and power. In addition, with the highly specific inclusion/exclusion criteria, the findings cannot be generalized to other stages of endometriosis or other causes of chronic pelvic pain. The second limitation, as mentioned in a related publication,11
is that some of the instruments used to assess outcomes have not been specifically validated in adolescent populations. The Endometriosis Health Profile, for instance, has been validated for populations of adults older than 18 years, but not younger adolescents. Third, the derived imbalance measures in this study used simple statistics. It is possible that more complex, even nonlinear measures would better reflect clinical outcomes. Fourth, the results cannot be generalized to other clinical conditions or to other electrodermal devices. Fifth, the acupuncturists were not blinded to treatment designation and may have biased the electrodermal measurements. Sixth, the acupuncture group had higher electrodermal dispersion and asymmetry values at baseline compared to the sham group. It is conceivable that the observed temporal differences in electrodermal measurements between treatment groups could be attributed to this disparity. Finally, the technical limitations of the Hibiki-7 device remain largely unaddressed. How do stratum corneum moisture, electrode pressure, and variations in point localization affect the electrodermal readings? How do these factors affect interrater and intrarater reliability? Is there substantial temporal variability? In addition, the technical details of the Hibiki-7 device were not fully assessed, and the precision and proper calibration of the device have not been fully evaluated. While the device used for this study was not built specifically for scientific research, its use in this pilot study has generated findings that are interesting and suggestive enough (despite the problems discussed) to support further research into this area with a more technically sound electrodermal measurement device such as the Apparatus for Meridian Identification (AMI-Motoyama Institute of Life Physics, Tokyo, Japan) or the Prognos device (MedPrevent, Walderschorf, Germany). The measurements should be made by a technician blinded to treatment and patient outcomes.