Over the last decade, there's been an explosion of "alternative" diagnostic methods purporting to identify nutrient deficiencies, detect environmental toxins, predict serious diseases, and help guide health conscious individuals in their diet and supplementation choices.
The popularity of things like iridology, bio-impedance testing, hair analysis, applied kinesiology, meridian analysis, oxidative stress measurement and others is part of the broader movement toward patient self-empowerment, self-care and personal responsibility. Many people know they're not eating healthy diets and living health-engendering lifestyles. Their concerns are warranted, and their impulses to better their health should be encouraged.
But are these testing methods valid? Can they really provide the guidance our patients seek? In this second part of our series exploring some of the most common "over-the-counter" alternative diagnostic methods, I will take a closer look at Electrodermal Testing.
Electrodermal testing (ET) has its roots in acupuncture as practiced in Europe in the 1950s, and is based on the principle of galvanometric skin differentials combined with classical Chinese acupuncture theory. In short, the underlying idea is that there is a connection between the skin's electrical characteristics and the health of the internal organs, and that the electrical signals measurable on the skin surface can provide useful diagnostic information.
Reinhold Voll, MD, a German physician, developed the first electrodermal system, called the Dermatron, in the 1950's and laid the groundwork for what became known as Electroacupuncture of Voll (EAV). One of Voll's physician students simplified this system creating a second model called the Vegatest. They were developed with an eye toward modernizing and standardizing acupuncture practice by providing clinicians with "objective" measures to help guide acupuncture point selection.
A Plethora of Methods
Since Voll's time, electrodermal testing has been adopted by a wide range of "alternative" healthcare practitioners using it for many different things, including nutrition counseling and prescription of homeopathic remedies. Today it goes by many different names, including Electrodermal Screening (EDS), Bioelectric Functions Diagnosis (BFD), Bio Resonance Therapy (BRT), Bioenergy Regulatory Technique (BER), Biocybernetic Medicine (BM), Computerized Electrodermal Screening (CEDS), and electrodiagnosis.
There is an equally dizzying roster of different devices in use, such as the Accupath 1000, Asyra, Biotron, BICOM, Computron, Diagnose, Elision, e-Lybra 8, Last, Interro, Interactive Query System (IQS), LISTEN System, MORA, Matrix Physique System, Omega Vision, Orion System. The FDA classifies these as Class III devices requiring approval prior to marketing.
But all of these are based on the same core principle, grounded in the Chinese medical theory that the skin surface contains specific acu-points, referred to as "organ projection" areas by ET practitioners.
Acupoints & "Organ Projection Areas"
The skin's galvanic resistance is measured with the use of positively and negatively polarized electrodes (i.e., electrical current rectification). The theory holds that if an internal organ is diseased, the organ projection areas corresponding to that organ will "rectify" an applied electrical current from the probe. The organ projection areas of a diseased organ will show a higher resistance measured by the positive electrode compared with the negatively charged electrode. Finally, with diseased internal organs, impedance of the corresponding organ projection areas is increased. These changes are not seen for healthy organs.
In summary, the degree of skin rectification and the change in skin impedance are thought to be proportional to the extent of disease in involved organs. In a sense, the idea is not so different from the core principles of electrocardiography or electroencephalography, which use skin surface electrical patterns to assess heart or brain function.
Electrodermal devices emit direct electrical current that will flow through a wire from the machine to a brass cylinder covered by moist cloth held by the patient in one hand. Another wire connects from the device to a probe, touched by the technician to acupuncture points on the other hand or ear, etc. The diagnostic information is relayed on a printout with a scale of 0 to 100 microamperes.
According to Voll's original work, readings above 55 indicate inflammation of the organ associated with the acupoint tested. Readings below 45 may indicate organ degeneration. Most of the modern systems convert the numerical values to more qualitative "organ" readings, using nomenclature like "healthy," "within normal limits," "subacute," "acute," etc.
One could make a strong argument that the central principle of ET is sound: there's no doubt that there are measurable galvanic currents along the skin surface. The question is whether the patterns of these currents are reflective of the functional condition of various organ systems.
Questions & Uncertainties
There are many uncertainties associated with ET, such as the accuracy of the organ projection points posited by ET theory (and the classical Chinese acupuncture theory before it) and the degree to which they actually correlate with organ systems. Assuming there is a reliable correlation, there's still the question of whether galvanic currents on the skin surface can really detect the specific conditions some ET practitioners claim to be able to diagnose.
These days, ET is being used to identify "energy imbalances," detect hay fever and other allergies, food sensitivities, vitamin deficiencies, and mercury toxicities due to mercury amalgam dental fillings. Depending on test results, the ET practitioner may recommend (or sell) a range of homeopathic products, dietary supplements or other treatment interventions.
I am not aware of any clinical data supporting ET as diagnostic for any of the aforementioned conditions. In fact, there are only a few well-designed human clinical trials looking at this techique at all.
Lewith and colleagues (total of 4 operators) conducted a double blind study comparing the Vegatest to skin prick testing for allergies to cat dander or dust mites. The study was powered at 90% to detect the presence or absence of allergy for each subject at a 5% level of significance. The authors concluded that ET did not correlate with skin prick testing and should not be used to diagnose these allergies (Lewith G. BMJ. 2001; 322: 131–134). The Australian College of Allergy concurred with Lewith's recommendation.
Detecting Problems, But Not Their Causes
Dr. Jan Z. Szopinski and colleagues at the Mayo Medical Centre and University of the Witwatersrand, Johannesburg, studied the diagnostic accuracy of an electrodermal device manufactured by Diagnotronics (South Africa). The study was designed to test the ability of ET to correctly detect the presence and extent of disease in 200 hospital inpatients with known or highly suspected pathologies of the esophagus, stomach, gallbladder, pancreas, colon, kidneys, urinary bladder and prostate. The investigators took auricular electrodermal readings for a total of 714 subject organ sites.
They reported that 630 of the 714 readings were deemed to be "true" and reflective of specific organ pathology, an overall detection rate of 88% (95% CI: 85.6–90.5%). They note that, "the degree of rectification or difference in impedance is proportional to the extent of the pathological process within the tested organ," a finding that seems to be in accord with the principles of ET (Szopkinski JZ, et al. SAMJ. 2004; 94: 547–551).
Testing sensitivity was 89.5% (CI: 85.2–92.8%), specificity was 87.5% (CI: 84–90.4%), and predictive value for positive results was 81.7% (CI: 76.9–85.9%) and for negative results, 93% (CI: 90.1–95.2%). The negative predictive for healthy organs was stronger than the positive value. Of note, only internal organs with proven clinical conditions were included in statistical analysis.
This study has its limitations: For one, we are not told how many investigators took part; Secondly, the authors reported that pressure of the measuring electrode had some influence on reported results while at the same time claiming that this did not affect final diagnoses. The published report does not outline the power calculation needed to match clinical diagnoses and electrodermal results to an a priori (p < 0.05) level of statistical significance.
That said, Dr. Szopinski's research does seem to validate the basics of ET. "So-called OPAs (organ projection areas) do exist on the skin surface. Pathology of a particular organ causes a related OPA to rectify electrical currents once the resistance 'breakthrough effect' has been induced in the skin." He adds that, "Healthy organs usually produced the … result 'healthy' or 'within normal limits', while subacute pathology displayed 'subcute' and acute pathology 'acute.'"
But Dr. Szopinski makes one more very important point: "The results were not affected by either the type or the aetiology of disease, that is, OED (organ electrodermal diagnostics) estimated the actual extent of pathological process activity within particular organs but did not directly explain the cause of pathology." Yet this is precisely what many ET practitioners will claim to do: detect specific causes for organ pathology.
Accuracy & Reproducibility
There are several other small studies of ET in the literature, showing equivocal outcomes. It is difficult to draw strong conclusions, because there are many variables that could affect the accuracy of ET measurements. These include: incorrect medical theory regarding organ projection areas upon the skin; lack of validated comparisons of different skin locations for the probe placement; inter-operator variability; a patient's skin hydration status; environmental humidity; the amount of moisture on the cloth covering the ET probe held by the patient; the patient's use of skin creams or other cosmetics that might interfere with current flow; and the amount of pressure used with the probe (e.g., higher pressure increases the flow of electrical current between the device and the skin).
Practitioner credentialing is also an important issue. Currently there are no widely recognized standards for ET practitioner training and certification.
We certainly need more clinical trials before we can definitively accept or refute the diagnostic value of ET. Absence of these studies, however, will probably not quell the enthusiasm of either patients or practitioners of ET. The danger is that incorrect diagnoses based on ET may cause harm, waste healthcare dollars, unduly frighten people with conditions they do not actually have, or prevent them from seeking medical attention for a condition that was missed because of a false-negative ET.
Still, ET may yet prove to hold valuable information about an individual's functional status, overall health or emerging disorders. At minimum, it should be combined with a medical history, general physical exam, and appropriate lab testing by a well-trained physician.
As is always the case with "alternative" diagnostic tests, the fact that a patient is seeking ET is a signal that he or she wants to move in the direction of health and is seeking to understand what is happening in his or her body. So while there may be big questions about the specific testing method, the motive is a good one and should be honored.
At the same time, clinicians should be aware that regulations on the use of experimental techniques like ET vary widely from state to state, as can interpretation or enforcement of stated regulations. In one highly publicized case in 2004, Geoffrey Ames, MD, of Redland, WA, faced a 5 year suspension of his medical license just for demonstrating, but not actually using EAV on a patient.