Can we evaluate electrodermal testing?

Food Allergy: Unproven diagnostics and therapeutics

Food allergy or intolerance is often attributed by patients as the cause of many symptoms unknown to be directly related to food ingestion. For immunoglobulin E (IgE) mediated food allergy, diagnostic modalities are currently limited to the combination of clinical history, evidence of sensitization with food-specific IgE testing and skin-prick testing, and oral food challenge. Many patients find an appeal in the promise of identification of the etiology of their symptoms through alternative food allergy or intolerance diagnostic modalities. These patients may seek guidance from allergists or their general providers as to the legitimacy of these tests or interpretation of results. These tests include food-specific serum IgG or IgG4 testing, flow cytometry to measure the change in leukocyte volume after exposure to food, intradermal or sublingual provocation-neutralization, electrodermal testing, applied kinesiology, hair analysis, and iridology. In addition, there are some unconventional therapeutic modalities for adverse reactions to foods, including rotary diets. None of these have been supported by scientific evidence, and some even carry the risk of severe adverse reactions. It is important that we offer our patients evidence-based, accurate counseling of these unproven modalities by understanding their methods, their paucity of credible scientific support, and their associated risks.

Unproven Diagnostic Tests for Food Allergy

The gold standard for diagnosis of immunoglobulin E (IgE)-mediated food allergy remains the oral food challenge, with serum IgE testing and skin prick testing serving as acceptable alternatives. However, the increase in prevalence of food allergy (both physician diagnosed and patient suspected) has led patients to pursue a variety of other alternative diagnostic procedures for suspected food allergy, which are reviewed in this article. These procedures (IgG testing, electrodermal testing, cytotoxic testing, provocation/neutralization, and applied kinesiology) have largely been unproven and may lead to unnecessary elimination diets.

Impact of Surgical Intervention and Postoperative Pain on Electrical Skin Resistance at Acupuncture Points: An Exploratory Study

Objectives

One theory about acupuncture suggests that pathological processes can cause measurable changes in electrical skin resistance (ESR) at acupuncture points (APs). Although the theory has yet to be proven, ESR measurements (ESRMs) form a frequently used part of contemporary acupuncture. The aim of this study was to test the so-called ‘electrical responsiveness’ of APs in the setting of a defined operative trauma.

Methods

ESRMs (n=424) were performed at the APs and surrounding skin of GB34 and ST38 in 163 participants using an impedance meter array developed for the purpose of ESRMs. For each group the percentage of measurements with a significantly different ESR between the APs and the surrounding skin was calculated and compared with each other. Measurements of four groups were compared: healthy control subjects (n=30) and patients after ophthalmic (n=29), hip (n=42) and shoulder (n=30) surgery. The influence of postoperative pain intensity was also assessed.

Results

Group comparison showed no significant differences for ST38. The ESRMs at GB34 had a significantly higher percentage of measurements with an increased ESR after ophthalmic (23.2%) and hip (22.2%) surgery, but not after shoulder surgery (7.5%). Subgroup analysis showed that an increase in pain intensity tended to lead to a decrease in the number of APs with ESR changes.

Conclusion

These results suggest that reactive changes in ESR at APs might exist. Pain and alertness seem to have an impact on ESR at APs. However, the current data do not allow for conclusions to be drawn concerning the clinical use of ESRMs.

Lung meridian acupuncture point skin impedance in asthma and description of a mathematical relationship with FEV1

Alteration in acupoint skin impedance is purportedly associated with health impairment. This study examined lung meridian acupoint skin impedance in healthy individuals and patients with controlled asthma and the relationship if any with Forced Expiratory Volume in 1s (FEV(1)). Twenty-eight subjects diagnosed with asthma and 28 age and gender-matched healthy subjects had their FEV(1) and skin impedance, at acupoints LU 7 (Lieque) and LU 9 (Taiyuan) on the lung meridian, measured. Skin impedance was significantly higher in subjects with asthma (p<0.05) and negatively correlated with percent predicted FEV(1) (r=-0.34 to -0.40, p<0.005). The Receiver Operating Characteristic (ROC) suggested the cutoff point for logarithm-transformed mean of skin impedance for asthma was ≥3.59 unit (sensitivity=82.1%, specificity=82.1%) (AUC=0.878, p<0.001). A regression prediction equation of asthma was derived. This study suggests that acupoint skin impedance on the lung meridian may reflect the asthma condition. The use of skin impedance as an adjunctive, objective assessment in asthma screening and treatment monitoring, warrants further investigation.

Skin impedance measurements for acupuncture research: development of a continuous recording system

Skin impedance at acupuncture points (APs) has been used as a diagnostic/therapeutic aid for more than 50 years. Currently, researchers are evaluating the electrophysiologic properties of APs as a possible means of understanding acupuncture's mechanism. To comprehensively assess the diagnostic, therapeutic and mechanistic implications of acupuncture point skin impedance, a device capable of reliably recording impedances from 100 kΩ to 50 MΩ at multiple APs over extended time periods is needed. This article describes design considerations, development and testing of a single channel skin impedance system (hardware, control software and customized electrodes). The system was tested for accuracy against known resistors and capacitors. Two electrodes (the AMI and the ORI) were compared for reliability of recording over 30 min. Two APs (LU 9 and PC 6) and a nearby non-AP site were measured simultaneously in four individuals for 60 min. Our measurement system performed accurately (within 5%) against known resistors (580 kΩ–10 MΩ) and capacitors (10 nF–150 nF). Both the AMI electrode and the modified ORI electrode recorded skin impedance reliably on the volar surface of the forearm (r = 0.87 and r = 0.79, respectively). In four of four volunteers tested, skin impedance at LU 9 was less than at the nearby non-AP site. In three of four volunteers skin impedance was less at PC 6 than at the nearby non-AP site. We conclude that our system is a suitable device upon which we can develop a fully automated multi-channel device capable of recording skin impedance at multiple APs simultaneously over 24 h.

Use of complementary and alternative medicine by food-allergic patients

BACKGROUND

Interest in complementary and alternative medicine (CAM) is increasing. Use of CAM in food-allergic patients has not previously been evaluated.

OBJECTIVES

To determine the prevalence of CAM use, the types of CAM modalities used, and opinions about CAM in food-allergic patients.

METHODS

A questionnaire was distributed to attendees at a patient conference in 2002 and to patients at pediatric food allergy clinics in 2005.

RESULTS

Surveys were completed by 380 families. Respondents were mainly white, parents of children with multiple food allergies, and from the tri-state (New York, New Jersey, Connecticut) area. Diagnostic modalities considered unproven or disproven (such as serum IgG4, electrodermal skin testing, and kinesiology) were used by 22% of respondents; CAM therapies were used by 18%. Participants used several types of CAM practitioners, the most common being chiropractors, homeopaths, and acupuncturists. Only 49% of patients using CAM disclosed this to their physicians. Efficacy ratings for CAM were poor. Regarding participants' opinions, an herbal therapy of equal efficacy, safety, and cost was preferred to a pharmaceutical drug (37% vs 12%; P = .001), but most participants (51%) had no preference or were unsure.

CONCLUSION

Unproven or disproven diagnostic methods and CAM treatments were used by approximately 1 in 5 respondents. Those using CAM noted poor efficacy, but if given a choice, many would prefer herbal therapies to pharmaceutical drugs. Education regarding reliable testing for food allergy and further research on CAM therapies are warranted.

[A new sensor technique for measurements of electrical potential profiles of human skin at acupuncture points]

From an electro-physiological point of view human skin shows an inhomogeneous pattern regarding its electrical resistance: in certain areas a decreased electrical resistance can be observed. It has been postulated that these areas correspond to acupuncture points. Subsequently, devices have been developed as detectors for acupuncture points which are used for diagnosis and treatment in acupuncture. However, most of these devices are inconsistent: they show a remarkable inaccuracy in their measurements and are poorly evaluated. Further analyses have shown that the measuring pens often used are subject to various disturbances such as pressure, angle of measurement, humidity of the skin, different thickness of stratum corneum of the skin and external disturbances such as temperature and humidity in the measuring room.

MATERIAL AND METHODS

We present a new device for standardized measuring of electrical skin resistance. It consists of a field of 64 electrodes (measuring array) on a surface of 60 x 60 mm(2) and a distance of 8 mm between electrodes. For a more precise spatial resolution a field of 32 electrodes on a surface of 3.5 x 3.5 mm(2) with a distance of 0.65 mm is available. A high, precise, temporal resolution of electric potentials in human skin is realized by fast scanning of the electrodes. Technical details are described.

CONCLUSIONS

First analyses of collected data show that reliable and valid measurements are possible. Using this device in a controlled and blinded study design will help elucidate the issue of altered skin resistance at acupuncture points and clarify if this phenomenon is unique at acupuncture points.