<i>Skin Impedance in Relation to Pain Threshold Testing by Electrical Means</i>

Mueller, Emily E.; Loeffel, Robert; Mead, Sedgwick

doi:10.1152/jappl.1953.5.12.746

Cited by 28 publications

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“…26,27 Electrical stimulation may introduce local physiological changes which may modify the ionic microenvironment and result in changes in skin resistance or impedance. 28,29 Similar to previous experiments, this study used constant current stimuli; hence, the intensity of the stimulating current was independent of skin resistance but not of impedance. 20 Tursky and Greenblatt 30 describe the electrode-skin circuit as two high impedance electrode-skin junctions connected by a subsurface low impedance network, whose configuration changes to a low impedance cir-Fig.…”

Section: Discussionmentioning

confidence: 94%

Stability and Reliability of Detection Thresholds for Human A-Beta and A-Delta Sensory Afferents Determined by Cutaneous Electrical Stimulation

Sang

Max

Gracely

2003

Journal of Pain and Symptom Management

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Activity in primary afferent fibers that usually mediate fine touch can evoke sensations of pain in conditions in which there is sensitization of central neurons. Input from these large diameter Abeta afferents may also sustain and exacerbate these central mechanisms. The role of these fibers in clinical pain syndromes can be evaluated by applications of electrical stimuli that preferentially activate Abeta axons. This study assessed the stability and reliability of a method of electrical stimulation (ES) useful for clinical evaluation. Monopolar constant-current rectangular pulses were delivered to 5 equi-spaced sites on the volar aspect of the left forearm along a transverse line 5 cm distal to the antecubital crease. Current intensity was gradually increased to determine detection threshold and pain detection threshold. This study determined: 1) Effect of pulse duration (1, 2, and 5 msec); 2) the variation of detection threshold and pain threshold over repeated stimulation; 3) the effect of electrode position with respect to distance from the trunk of underlying ulnar or median nerves; and 4) the effect of re-positioning the electrode on variability of detection threshold and pain threshold. There was no significant variability over time for either detection threshold (DT) or pain threshold (PT) at any of the 3 pulse durations tested. There was also no significant effect on variability of shifting the electrode between sites, nor was there a significant difference in variability between sites when placed either over or adjacent to peripheral nerves. Under simulated clinical conditions of electrode re-positioning, the mean detection threshold in 300 trials and ten subjects was 0.30 mA with an overall standard error of 0.007, standard errors of 0.014 over the 10 subjects, 0.003 over the 6 trials, and 0.012 over the 5 locations. Similarly, mean pain threshold in these 300 trials was 3.24 +/- 0.093, with standard errors of 0.12 over the 10 subjects, 0.023 over the 6 trials, and 0.13 over the 5 locations. Mean ratio of pain threshold divided by detection threshold ratio was 10.9 +/- 0.25 with a range of 2.0-28.3. Single pulse, constant current electrical stimulation of the skin at threshold levels is a quantifiable and reliable sensory method that is repeatable within and between testing sessions. Our results suggest that in skin unaffected by allodynia, a ratio of the two sensory thresholds (pain threshold and detection threshold) of less than 2.0 is uncommon. We propose that, in the presence of mechanical allodynia, a pain threshold/detection threshold of less than 2.0 suggests that altered central nervous system processing of Abeta input may contribute to allodynia.

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Section: Discussionmentioning

confidence: 94%

Stability and Reliability of Detection Thresholds for Human A-Beta and A-Delta Sensory Afferents Determined by Cutaneous Electrical Stimulation

Sang

Max

Gracely

2003

Journal of Pain and Symptom Management

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“…These factors are likely to facilitate recruitment of afferents at low intensity levels (low THR levels, hence tongue's high sensitivity to ETS). Similarly, as electrical stimulation is likely to more uniformly spread through the tissue due to the presence of saliva, more mechanoreceptor afferents will be activated without producing pain caused by high density spots (higher MAX levels; Mueller et al 1953). Only the lips have shown similar THR levels, but these are inconveniently accompanied by lower DR dB s (Liu and Tang 2005).…”

Section: Discussionmentioning

confidence: 99%

Electrotactile stimulation on the tongue: Intensity perception, discrimination, and cross-modality estimation

Lozano

Kaczmarek

Santello

2009

Somatosensory & Motor Research

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Due to its high sensitivity and conductivity, electrotactile stimulation (ETS) on the tongue has proven to be a useful and technically convenient tool to substitute and/or augment sensory capabilities. However, most of its applications have only provided spatial attributes and little is known about (a) the ability of the tongue's sensory system to process electrical stimuli of varying magnitudes and (b) how modulation of ETS intensity affects subjects' ability to decode stimulus intensity. We addressed these questions by quantifying: (1) the magnitude of the dynamic range (DR; maximal comfortable intensity/perception threshold) and its sensitivity to prolonged exposure; (2) subjects' ability to perceive intensity changes; and (3) subjects' ability to associate intensity with angular excursions of a protractor's handle. We found that the average DR (17 dB) was generally large in comparison with other tactile loci and of a relatively constant magnitude among subjects, even after prolonged exposure, despite a slight but significant upward drift (P < 0.001). Additionally, our results showed that as stimulus intensity increased, subjects' ability to discriminate ETS stimuli of different intensities improved (P < 0.05) while estimation accuracy, in general, slightly decreased (increasing underestimation). These results suggest that higher ETS intensity may increase recruitment of rapidly adapting mechanoreceptor fibers, as these are specialized for coding stimulus differences rather than absolute intensities. Furthermore, our study revealed that the tongue's sensory system can effectively convey electrical stimuli despite minimal practice and when information transfer is limited by memory and DR drift.

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“…Using electrical stimulation to determine cutaneous pain thresholds, MUller, Loeffel & Mead (44), concluded that prick, the only clear-cut pain end point, cannot be evoked when skin impedance is low. They suggest that prick is not an index of pain threshold but occurs during the breakdown of skin impedance and is, therefore, dependent on the di-electric properties of skin.…”

Section: The Recent Paper By Henselmentioning

confidence: 99%

Somesthesis and the Chemical Senses

Weddell¹

1955

Annu. Rev. Psychol.

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Experimental work in the fields of somesthesis and the chemical senses has been and is still [Adrian (1)] dominated by certain concepts which have proved so convenient that they have come to be accepted without serious question by the majority of physiologists and by many psychologists. These concepts are Muller's so-called "law" of specific nervous energies, and von Frey's extrapolation of this law into the theory of punctate representation of primary sensory modalities. In other words, it is commonly accepted that there are mo ; phologically specific pain, warmth, cold, and touch nerve end ings, specific nerve fibres, and specific nerve pathways.It is for this reason that so much emphasis has been laid on the analysis of somesthesis and the chemical senses in terms of the activity of single nerve fibres, which has resulted in reviews that consist of collations of literature reporting the results of e1ectrophysiological experiments.Recent anatomical and psycho-physiological work, however, has seri ously challenged the validity of Muller's law and von Frey's theory with re gard to cutaneous sensibility, and has made it necessary to re-examine all the experimental observations on the sensory nervous system from a wholly different point of view. This revieJ.V will, therefore, take a somewhat unconventional form. In the first place, we shall examine and collate the evidence which seeks to refute the accepted concepts and then, in the light of these new observations, ex amine some of the literature in the field of somesthesis which has appeared in the course of the past year. The literature on the chemical senses was ably reviewed in Volume 5 of the Annual Review of Psychology and for this reason has been dealt with less exhaustively on this occasion. The review is intended to be provocative and critical, and necessarily reflects the author's personal opinion of the evidence before him. SOMESTHESISRecent observations on the mechanism of cutaneous sensibility.-The state ments which follow are based on a series of publications by Weddell and his co-workers (2 to 21) , some of which appeared before 1953. Reference should be made to all of these publications if exhaustive examination of the evi dence is desired.Neurohistological observations have shown that in the skin of the human ear and in hairy skin from elsewhere, i.e., abdomen and forearm, there are but two morphologically separable types of nerve termination: unencapsu lated (free) nerve endings and nerves ending in hair follicles of different

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Skin Impedance in Relation to Pain Threshold Testing by Electrical Means

Cited by 28 publications

References 0 publications

Stability and Reliability of Detection Thresholds for Human A-Beta and A-Delta Sensory Afferents Determined by Cutaneous Electrical Stimulation

Stability and Reliability of Detection Thresholds for Human A-Beta and A-Delta Sensory Afferents Determined by Cutaneous Electrical Stimulation

Electrotactile stimulation on the tongue: Intensity perception, discrimination, and cross-modality estimation

Somesthesis and the Chemical Senses

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