Transcutaneous Electrical Stimulation on the Submental Area: The Relations of Biopsychological Factors with Maximum Amplitude Tolerance and Perceived Discomfort Level.

Transcutaneous electrical stimulation (TES) is a frequently used adjunctive modality in dysphagia rehabilitation. Stimulating deeper swallowing muscles requires higher TES amplitude. However, TES amplitude is limited by maximum amplitude tolerance (MAT). Previous studies have reported high interindividual variability regarding MAT and perceived discomfort. This variability might be one of the potential reasons of conflicting outcomes in TES-based swallowing studies. MAT and perceived discomfort are influenced by a variety of biopsychological factors. The influence of these factors related to swallow applications is poorly understood. This study explored the relation of biopsychological factors with MAT and perceived discomfort related to TES in the submental area. A convenience sample of thirty community-dwelling older adults between 60 and 70 years of age provided data for this study. Gender, submental adipose tissue thickness, perceptual pain sensitivity, and pain-coping strategies were evaluated for each subject. Subsequently, MAT and perceived discomfort level were determined using TES on the submental area. Relation of different biopsychological variables with MAT and discomfort level was examined using Pearson and Spearman correlation, and Mann-Whitney U test. Results indicated that neither gender nor adipose thickness was related to MAT and perceived discomfort. Among studied pain-coping strategies, catastrophizing was significantly related to MAT(r = - 0.552, p < .002). Distraction was significantly related to perceived discomfort level (r = - 0.561, p < 0.002). Given the negative impact of pain catastrophizing on MAT and the positive impact of distraction on perceiving discomfort, these coping strategies should be considered as amplitude-limiting and discomfort-moderating factors in TES-based dysphagia rehabilitation.

Factors Affecting and Adjustments for Sex Differences in Current Perception Threshold With Transcutaneous Electrical Stimulation in Healthy Subjects.

OBJECTIVE: Current perception threshold (CPT) measurement is a noninvasive, easy, and semi-objective method for determining sensory function using transcutaneous electrical stimulation. Previous studies have shown that CPT is determined by physical characteristics, such as sex, age, physical sites, and presence of neuropathy. Although the CPT reported in males is clearly higher than that in females, the reason for this difference remains unclear. This study investigates the cause of sex-based differences in CPT and suggests an adjustment method, which may suppress the sex difference in CPT. MATERIALS AND METHODS: Electrical stimulation was applied with PainVision® via five sizes of circular surface electrodes. Seventy healthy participants were examined thrice under each electrode. The relationship among body water percentage, body fat percentage, and CPT was then analyzed. RESULTS: CPT values are higher in males than that in females, with statistically significant sex differences with each electrode pairs (EL 1: p < 0.001; EL 2: p = 0.006; EL 3: p < 0.001; EL 4: p < 0.001; EL 5: p < 0.001). By adjusting for body fat percentage or body water percentage, the log-transformation values (CPT values) no longer exhibit sex differences with any electrode pairs (body fat: p = 0.09; body water: p = 0.08). CONCLUSION: We conclude that sensitivity for perceiving electrical stimulation can be influenced by the subjects' characteristics, such as body fat or body water percentages.

Randomized study of the impact of a therapeutic education program on patients suffering from chronic low-back pain who are treated with transcutaneous electrical nerve stimulation.

BACKGROUND: Transcutaneous electrical nerve stimulation (TENS) is often used for the treatment of low-back pain (LBP). However, its effectiveness is controversial. OBJECTIVE: To determine the efficacy of TENS in the treatment LBP when associated to a therapeutic education program (TEP). DESIGN: Open randomized monocentric study. SETTING: University hospital between 2010 and 2014. PATIENTS: A total of 97 patients suffering from LBP. INTERVENTIONS: Routine care (TENS group) or routine care plus a therapeutic education program (TENS-TEP group) based on consultation support by a pain resource nurse. MAIN OUTCOME MEASURES: EIFEL and Dallas Pain Questionnaire scores. RESULTS: Twenty-two patients (44%) were still assessable at the end-of-study visit, whereas 33 (70%) were assessable at the same time point in the TENS-TEP group (P = .013). The EIFEL score and the Dallas score had a similar evolution over time between groups (P = .18 and P = .50 respectively). Similarly, there were no significant differences between the groups with respect to resting pain scores (P = .94 for back pain and P = .16 for leg pain) and movement pain scores (P = .52 for back pain and P = .56 for leg pain). At Month 6, there was no significant difference between the groups (P = .85) with regard to analgesics and social impact. Two patients presented a serious adverse event during the study (one in each group) but non-attributable to the treatment studied. CONCLUSION: This study does not support the use of TENS in the treatment of patients with chronic LBP even though patients benefited from a therapeutic education program by a pain resource nurse. However, the higher number of premature withdrawals in the TENS group may be due to early withdrawal of patients who did not experience improvement of their symptoms.

Autonomic Arousal as a Mechanism of the Persistence of Nocebo Hyperalgesia.

Placebo and nocebo mechanisms can lead to clinically significant modulation of pain. Although learning is considered to be the broad mechanism underlying placebo analgesia as well as nocebo hyperalgesia, critical differences have emerged in their specific mechanisms. One of the most interesting of these is that whereas placebo analgesia seems to be relatively short-lived, nocebo hyperalgesia appears more resistant to extinction, often persisting indefinitely. The current study examined why nocebo hyperalgesia persists longer than placebo analgesia. Sixty healthy volunteers were randomized to receive placebo conditioning, nocebo conditioning, or no conditioning using an experimental pain model with surreptitious decreases (placebo group) and increases (nocebo group) in pain stimulation paired with sham treatment during training. Pain was then assessed in a test phase with and without the sham treatment at equal pain stimulation. The conditioning procedure successfully induced placebo analgesia as well as nocebo hyperalgesia in the relevant groups, with nocebo hyperalgesia outlasting placebo analgesia, confirming nocebo hyperalgesia's resistance to extinction. Most interestingly, nocebo treatment led to heightened anticipatory anxiety ratings and autonomic arousal. Further, autonomic arousal completely mediated the effect of nocebo versus placebo training on extinction, suggesting that heightened autonomic arousal may be an important mechanism in the persistence of nocebo hyperalgesia. PERSPECTIVE: Heightened anticipatory anxiety in the form of elevated autonomic arousal may explain why nocebo hyperalgesia persists relative to placebo analgesia. As such, interventions that reduce anticipatory anxiety could reduce the burden of persistent nocebo hyperalgesia.

[The non-pharmacological management of chronic pain]. / La prise en charge non médicamenteuse de la douleur chronique.

Pain management is not limited to the putting in place of pharmacological, surgical, physiotherapy or psychological strategies. Non-pharmacological therapies can also be proposed, notably in relation to chronic pain. Appreciated by patients and developed by caregivers, they require appropriate regulatory guidelines and specific training in order for them to be implemented safely.

Modulation of temporal summation threshold of the nociceptive withdrawal reflex by transcutaneous spinal direct current stimulation in humans.

OBJECTIVE: Transcutaneous spinal direct current stimulation (tsDCS) modulates spinal cord pain pathways. The study is aimed to clarify the neurophysiology of the tsDCS-induced modulation of the spinal cord pain processing by evaluating the effect of the tsDCS on temporal summation threshold (TST) of the nociceptive withdrawal reflex (NWR). METHODS: In a randomized, double-blind, crossover study the effects of anodal, cathodal and sham tsDCS (2 mA, 15 min) applied on the skin overlying the thoracic spinal cord were investigated in 10 healthy subjects. RESULTS: Anodal tsDCS induced a long-lasting (up to 60 min) increase in TST of the NWR as well as a parallel decrease in related psychophysical temporal summation of pain, while cathodal and sham tsDCS resulted ineffective. CONCLUSIONS: Anodal tsDCS represents a non-invasive tool able to induce an early and long-lasting depression of the transitory facilitation of the wide dynamic range neurons activity at the basis of both the temporal summation of the NWR and the related temporal summation of pain sensation. SIGNIFICANCE: The modulation of the temporal processing of nociceptive stimuli could be effective in treating clinical pain conditions in which pain is generated by spinal cord structures.

Partial reinforcement, extinction, and placebo analgesia.

Numerous studies indicate that placebo analgesia can be established via conditioning procedures. However, these studies have exclusively involved conditioning under continuous reinforcement. Thus, it is currently unknown whether placebo analgesia can be established under partial reinforcement and how durable any such effect would be. We tested this possibility using electrocutaneous pain in healthy volunteers. Sixty undergraduates received placebo treatment (activation of a sham electrode) under the guise of an analgesic trial. The participants were randomly allocated to different conditioning schedules, namely continuous reinforcement (CRF), partial reinforcement (PRF), or control (no conditioning). Conditioning was achieved by surreptitiously reducing pain intensity during training when the placebo was activated compared with when it was inactive. For the CRF group, the placebo was always followed by a surreptitious reduction in pain during training. For the PRF group, the placebo was followed by a reduction in pain stimulation on 62.5% of trials only. In the test phase, pain stimulation was equivalent across placebo and no placebo trials. Both CRF and PRF produced placebo analgesia, with the magnitude of initial analgesia being larger after CRF. However, although the placebo analgesia established under CRF extinguished during test phase, the placebo analgesia established under PRF did not. These findings indicate that PRF can induce placebo analgesia and that these effects are more resistant to extinction than those established via CRF. PRF may therefore reflect a novel way of enhancing clinical outcomes via the placebo effect.

A double blind randomised controlled clinical trial on the effect of transcutaneous spinal electroanalgesia (TSE) on low back pain.

A double blind randomised controlled clinical trial on the effect of transcutaneous spinal electroanalgesia (TSE) on low back pain was carried out in 58 patients attending a Pain Management Unit. Four TSE instruments, two active and two sham, were used and each patient was assigned randomly to one of these. Low back pain was rated by each patient using a visual analogue scale (VAS) immediately before and immediately after a single 20 min treatment of TSE and also daily for the week prior to, and the week following, the treatment. No significant difference in mean pain score was detected between the active and sham treated groups immediately after treatment or during the subsequent week. The Hospital, Anxiety and Depression scale (HAD) and the General Health Questionnaire (GHQ) were completed by each patient and there was a positive correlation between the scores achieved on these scales and the mean pain scores in both the active and sham treated groups. A post-trial problem was the discovery that the specification of the two active TSE machines differed from the manufacturer's specification. Thus, the output frequencies were either more (+10%) or less (-17%) while the maximum output voltages were both less (-40% and -20%), respectively. However, additional statistical analysis revealed no significant differences between the results obtained with the two active machines.

Reductions in self-injury produced by transcutaneous electrical nerve stimulation.

Transcutaneous electrical nerve stimulation is used to reduce pain but also may be useful for self-injurious behavior (SIB). In the current investigation, a microcurrent electromedical device, classified as a transcutaneous electrical nerve stimulator (TENS), was applied with a man with Down syndrome who displayed SIB that persisted in the absence of social contingencies. Although clinically significant results were not maintained, a clear difference in the rates of SIB during active and inactive TENS was observed.

Dentist and patient evaluation of an electronic dental analgesia system.

Questionnaires were used to evaluate operators' and patients' attitudes to a recently introduced electronic dental analgesia system. Five participating dentists were given 30 minutes' instruction in the use of the system and asked to offer the use of the system to patients who expressed an interest in using the system or anxiety to administration of local anesthesia. The system, used for 113 patients, was considered most useful for placement of Class I and Class V restorations and procedures such as crown or prosthesis insertion. The system was considered most suitable for patients who disliked needles or numbness. Principal difficulties encountered were the time-consuming nature of the system and the differing electrode sites required for different patients. Major benefits identified were the absence of drugs, needles, residual numbness, and invasiveness and a reduction in anxiety in needle phobics. Forty-one percent of patients indicated that the system controlled discomfort more effectively than did local anesthesia. Seventy-two percent of respondent patients stated that they would request its use for future treatment.

Electronic anesthesia versus topical anesthesia for the control of injection pain.

The ability of a dental transcutaneous electronic nerve stimulator to control pain from injection of local anesthesia was compared to the pain-controlling ability of topical anesthesia. Two maxillary infiltration injections were completed on 21 patients, one injection after electronic anesthesia, the other after topical anesthesia. Patients reported the level of pain caused when the needle pierced their tissue and the solution was injected and their overall evaluation of the injection. No difference was reported for piercing of the tissue; however, the level of pain was very low. Significantly less pain was reported for the injection of local anesthesia solution and the overall evaluation of the injection was more favorable when electronic anesthesia was used. The patients preferred the electronic technique three to one over the topical anesthesia.

A study of discomfort with electrical stimulation.

The primary purpose of this study was to investigate the influence of personality variables and contractile forces on magnitude estimates of pain unpleasantness and pain intensity during varying levels of neuromuscular electrical stimulation (NMES). Thirty volunteers, according to their scores on a preferred coping-style questionnaire, were assigned to one of two groups, one designated "monitors" (information seekers) and the other designated "blunters" (information avoiders). All subjects were administered varying levels of two types of NMES, one causing both afferent stimulation and muscle contraction and one causing only afferent stimulation. Subjects judged the intensity and unpleasantness of each current type using magnitude estimation. Data were analyzed using a 2 x 2 x 2 x 3 (coping style x current type x pain descriptor x current level) analysis of variance. The results indicated that the rate of increase of magnitude estimates for unpleasantness and pain intensity that corresponded to increases in current were dependent on (1) the preferred coping style of the subject, (2) whether the stimulus caused a muscle contraction, and (3) whether the subject was judging the intensity or the unpleasantness of the applied stimulus. Behavioral styles appear to affect how subjects characterize the discomfort associated with NMES, and involuntary muscle contractions contribute to the discomfort felt from NMES. These results suggest that interventions tailored to a preferred coping style may increase a subject's level of tolerance to NMES and thus provide a more beneficial treatment.

Effects of humorous stimuli and sense of humor on discomfort.

The effects of humor on increasing discomfort thresholds were tested with Transcutaneous End Nerve Stimulation (TENS). Undergraduate students (n = 31) with high or low scores on Martin and Lecourt's Situational Humor Questionnaire were randomly assigned to a humor or nonhumor condition. Discomfort thresholds for TENS were assessed before and during treatment. There was a significant increase in discomfort thresholds in the humorous treatment compared to the nonhumorous condition. Evidence was found for subjects to smile "wryly" (an increase in zygomatic and corrugator tensions) more during humorous stimuli than nonhumorous stimuli when they were waiting to be stimulated with the TENS.

Personality traits in the mechanisms of interferential therapy for osteoarthritic knee pain.

The role of hypochondriacal, depressive, and hysterical personality traits in response to interferential therapy (IFT) was studied in 50 patients with chronic knee osteoarthrosis. Personality traits were assessed through the Minnesota Multiphasic Personality Inventory. Each patient received ten sessions of IFT during two weeks. Pain relief was assessed subjectively (with a numerical pain-relief scale) at the end of treatment and one week later in a single-blind method. Patients who experienced pain relief of 50% or more were considered responders (n = 22). Those who experienced pain relief of 25% or less were considered nonresponders (n = 24). No statistically significant difference was found between the two groups on any of the personality traits studied. These personality traits apparently have no effect on the response of osteoarthritic knee pain to IFT.

A comparison of memory for induced ischaemic pain and chronic rheumatoid pain.

Ischaemic pain was induced in two groups of subjects. The pain was initially assessed using the McGill Pain Questionnaire and then by recall 7 days later. The pain experienced by a group of patients suffering from rheumatoid arthritis was similarly assessed before and after rehabilitatory surgery. Memory for the single episode of ischaemic pain was superior to that for the chronic rheumatoid pain.