Electrodermal Mapping of an Acupuncture Point and a Non-Acupuncture Point

Dear Editor:

Due to controversially discussed results in the scientific literature (Ahn and Martinsen ¹ and Quintanilha et al. ² ) concerning electrical skin impedance at acupuncture points and nonacupuncture points, a new measurement system was developed recently. ^3,4 Using this new electrodermal mapping system, a pilot study was performed at the Medical University of Graz (supported by the Federal Ministries of Health and of Science and Research and Eurasia-Pacific Uninet). This study was performed in 10 male volunteers, ages 20–30 years (mean age±standard deviation: 24.6±2.5 years) and of Caucasian descent. The aim of this study was to measure the skin resistance of an acupuncture point compared to a placebo point. The sensor of the system consists of an 8×6 electrode array with spring-mounted electrodes of gold-plated beryllium copper with a diameter of 0.9 mm. The point Kǒngzuì (Lu6) and a placebo point on the same level of the acupoint but located on the ulnar side of the heart meridian were used. These points were determined by an experienced acupuncture practitioner. Two (2) measurements were carried out per person. The results of the electrical characterization (skin resistance) of the areas surrounding the acupuncture point and the placebo point were then compared. The measurements of skin resistance at the acupuncture point showed lower impedance values than those taken from the placebo point on the same arm (Fig. 1). A significant (p<0.01; analysis of variance on ranks) difference of the values was found. Measured values on the acupuncture point were significantly lower (by 106 kΩ; mean values placebo point: 1218 kΩ, mean values acupuncture point 1112 kΩ). In the future, attention should be paid especially to possible confounders such as the pressure of electrodes as described by Ahn and Martinsen ¹ and Quintanilha et al. ² In this study, we investigated only male volunteers, since it was shown by Fogari et al. ⁵ that there are differences between the sexes, characterized by the lower external resistance in males than in females. With more subjects and points and avoiding the most common confounders, studies with higher quality may be achieved.

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FIG. 1.

Graphical analysis of 48 channels of electrodermal skin impedance (average values of n=10 persons) at an acupuncture point (below) and a nonacupuncture point (placebo point; above). Note the mean difference between the two surrounding areas is about 100 kΩ.