Transcutaneous electrical nerve stimulation activates peripherally located alpha-2A adrenergic receptors

Efficacy of cranial electrotherapy stimulation in patients with burning mouth syndrome: a randomized, controlled, double-blind pilot study

Background

The Burning mouth syndrome (BMS) is a chronic pain syndrome characterized by a burning sensation in the oral mucous membranes. The etiology and pathophysiology of BMS is largely unexplained. To date, there is no evidence-based treatment strategy for BMS. Cranial electrical stimulation (CES) represents a non-invasive treatment option with a low side effect profile that is approved for the treatment of pain, depression, anxiety disorder and insomnia. It has shown efficacy in studies for chronic pain such as fibromyalgia and neuropathic pain after spinal cord injury. This study aimed to investigate the therapeutic effectiveness of CES in combination with local transcutaneous electrical nerve stimulation (TENS) as an adjunct therapy in patients with BMS compared to sham stimulation.

Methods

This randomized, double-blind, sham-controlled pilot study enrolled 22 patients, aged 18 years and over, with the diagnosis of BMS meeting the ICHD-3 criteria from August 2020 to June 2021. The study duration was 4 weeks (28 days) per participant. After randomization, the active group participants (n = 11) received a 100 μA CES treatment for 60 min a day whereas the devices in the Sham group did not emit electricity. Simple linear regression was used to determine whether the interventions promoted significant differences in pain intensity.

Results

The linear regression showed that the period of stimulation significantly predicted decrease in the intensity of pain in the active group [β = -0.036; t(26) = -7.219; p < 0.001] as in the sham group [β = -0.026; t(26) = -2.56; p < 0.017]. With the applied cutoff of 30% pain reduction within the stimulation period, both the active and sham groups had 36% responders (n = 4) (Fisher's exact test, p = 1.00). In both groups (active stimulation and sham group), a significant decrease in the intensity of pain, somatic symptoms and an improvement in sleep quality over the study period was observed. Subjects reported no adverse events during the study.

Conclusion

Although CES is an easily applicable and safe therapeutic option for chronic facial pain, active stimulation was not superior to sham stimulation. Among other reasons, this could be due to the short double-blinded treatment period, duration of the daily stimulation session or the small sample size.

Prevalence, diagnosis and management of musculoskeletal disorders in elite athletes: A mini-review

Musculoskeletal injuries in elite sports are ones of the most impact issue because their remarkable impact on performance caused by drastic absence of training and competition and a progressive deterioration in physical health, emotional and social athletes' dimensions. Also, the prevalence of epidemiologic research found an incidence of musculoskeletal disorders vary within sports and in elite athletes which is even higher as a consequence of higher demand physical performance. This way, the loss of physical performance due to an sport injury impacts not only the individual economic sphere of the professional but also that ofsports entities, reaching, according to some studies, a loss estimated in the range of 74.7 million pounds. Thus, the purpose of this article is to review and to provide an overview of the most common musculoskeletal injuries in elite sports precipitating factors, clinical presentation, evidence-based diagnostic evaluation, and treatment recommendations with a view to preventing medical conditions or musculoskeletal injuries that may alter performance and general health in the elite athletes.

Transcutaneous Electric Nerve Stimulation in Animal Model Studies: From Neural Mechanisms to Biological Effects for Analgesia

OBJECTIVE

This systematic and meta-analysis review evaluated the transcutaneous electrical nerve stimulation (TENS)-induced action mechanisms for animal analgesia.

MATERIALS AND METHODS

Two independent investigators identified relevant articles published until February 2021 through a literature review, and a random-effects meta-analysis was performed to synthesize the results.

RESULTS

Of the 6984 studies found in the data base search, 53 full-text articles were selected and used in the systematic review. Most studies used Sprague Dawley rats (66.03%). High-frequency TENS was applied to at least one group in 47 studies, and most applications were performed for 20 minutes (64.15%). Mechanical hyperalgesia was analyzed as the primary outcome in 52.83% of the studies and thermal hyperalgesia in 23.07% of studies using a heated surface. More than 50% of the studies showed a low risk of bias on allocation concealment, random housing, selective outcome reporting, and acclimatization before the behavioral tests. Blinding was not performed in only one study and random outcome assessment in another study; acclimatization before the behavioral tests was not performed in just one study. Many studies had an uncertain risk of bias. Meta-analyses indicated no difference between low-frequency and high-frequency TENS with variations among the pain models.

CONCLUSIONS

This systematic review and meta-analysis suggests that TENS has presented a substantial scientific foundation for its hypoalgesic effect in preclinical studies for analgesia.

Neuropathic pain: From actual pharmacological treatments to new therapeutic horizons

Neuropathic pain, caused by a lesion or disease affecting the somatosensory system, affects between 3 and 17% of the general population. The treatment of neuropathic pain is challenging due to its heterogeneous etiologies, lack of objective diagnostic tools and resistance to classical analgesic drugs. First-line treatments recommended by the Special Interest Group on Neuropathic Pain (NeuPSIG) and European Federation of Neurological Societies (EFNS) include gabapentinoids, tricyclic antidepressants (TCAs) and selective serotonin noradrenaline reuptake inhibitors (SNRIs). Nevertheless these treatments have modest efficacy or dose limiting side effects. There is therefore a growing number of preclinical and clinical studies aim at developing new treatment strategies to treat neuropathic pain with better efficacy, selectivity, and less side effects. In this review, after a brief description of the mechanisms of action, efficacy, and limitations of current therapeutic drugs, we reviewed new preclinical and clinical targets currently under investigation, as well as promising non-pharmacological alternatives and their potential co-use with pharmacological treatments.

A Review of Chronic Pain and Device Interventions: Benefits and Future Directions

Chronic pain is a debilitating condition with a growing prevalence both in the USA and globally. The complex nature of this condition necessitates a multimodal approach to pain management that extends beyond the established pharmaceutical interventions currently employed. A variety of devices comprising both invasive and noninvasive approaches are available to patients, serving as adjuvants to existing regimens. The benefits of these interventions are notable for their lack of addiction potential, potential for patient autonomy regarding self-administration, minimal to no drug interaction, and overall relative safety. However, there remains a need for further research and more robust clinical trials to assess the true efficacy of these interventions and elucidate if there is an underlying physiological mechanism to their benefit in treating chronic pain or if their effect is predominantly placebo in nature. Regardless, the field of device-based intervention and treatment remains an evolving field with much promise for the future chronic pain management.

Using TENS for Pain Control: Update on the State of the Evidence

Transcutaneous electrical nerve stimulation (TENS) is a non-pharmacological intervention used in the treatment of acute and chronic pain conditions. The first clinical studies on TENS were published over 50 years ago, when effective parameters of stimulation were unclear and clinical trial design was in its infancy. Over the last two decades, a better understanding of the mechanisms underlying TENS efficacy has led to the development of an adequate dose and has improved outcome measure utilization. The continued uncertainty about the clinical efficacy of TENS to alleviate pain, despite years of research, is related to the quality of the clinical trials included in systematic reviews. This summary of the evidence includes only trials with pain as the primary outcome. The outcomes will be rated as positive (+), negative (-), undecided (U), or equivalent to other effective interventions (=). In comparison with our 2014 review, there appears to be improvement in adverse events and parameter reporting. Importantly, stimulation intensity has been documented as critical to therapeutic success. Examinations of the outcomes beyond resting pain, analgesic tolerance, and identification of TENS responders remain less studied areas of research. This literature review supports the conclusion that TENS may have efficacy for a variety of acute and chronic pain conditions, although the magnitude of the effect remains uncertain due to the low quality of existing literature. In order to provide information to individuals with pain and to clinicians treating those with pain, we suggest that resources for research should target larger, high-quality clinical trials including an adequate TENS dose and adequate timing of the outcome and should monitor risks of bias. Systematic reviews and meta-analyses should focus only on areas with sufficiently strong clinical trials that will result in adequate sample size.

Electrical stimulation of referred sensation area alleviates phantom limb pain

BACKGROUND

Patients with brachial plexus avulsion (BPA) usually experience phantom sensations and phantom limb pain (PLP) in the deafferented limb. It has been suggested that evoking the sensation of touch in the deafferented limb by stimulating referred sensation areas (RSAs) on the cheek or shoulder might alleviate PLP. However, feasible rehabilitation techniques using this approach have not been reported.

OBJECTIVE

The present study sought to examine the analgesic effects of simple electrical stimulation of RSAs in BPA patients with PLP.

METHODS

Study 1: Electrical stimulation of RSAs for 60 minutes was conducted for six BPA patients suffering from PLP to examine short-term analgesic effects. Study 2: A single case design experiment was conducted with two BPA patients to investigate whether electrical stimulation of RSAs was more effective for alleviating PLP than control electrical stimulation (electrical stimulation of sites on side opposite to the RSAs), and to elucidate the long-term effects of electrical stimulation of RSAs.

RESULTS

Study 1: Electrical stimulation of RSAs evoked phantom touch sensations in the deafferented limb, and significantly alleviated PLP (p < 0.05). Study 2: PLP was alleviated more after electrical stimulation on RSAs compared with control electrical stimulation (p < 0.05). However, the analgesic effects of electrical stimulation on RSAs were observed only in the short term, not in the long term (p > 0.05).

CONCLUSIONS

Electrical stimulation of RSAs not only evoked phantom touch sensation but also alleviated PLP in the short term. The results indicate that electrical stimulation of RSAs may provide a useful practical rehabilitation technique for PLP. Future studies will be required to clarify the mechanisms underlying immediate PLP alleviation via electrical stimulation of RSAs.

Resolving Long-Standing Uncertainty about the Clinical Efficacy of Transcutaneous Electrical Nerve Stimulation (TENS) to Relieve Pain: A Comprehensive Review of Factors Influencing Outcome

Pain is managed using a biopsychosocial approach and pharmacological and non-pharmacological treatments. Transcutaneous electrical nerve stimulation (TENS) is a technique whereby pulsed electrical currents are administered through the intact surface of the skin with the intention of alleviating pain, akin to 'electrically rubbing pain away'. Despite over 50 years of published research, uncertainty about the clinical efficacy of TENS remains. The purpose of this comprehensive review is to critically appraise clinical research on TENS to inform future strategies to resolve the 'efficacy-impasse'. The principles and practices of TENS are described to provide context for readers unfamiliar with TENS treatment. The findings of systematic reviews evaluating TENS are described from a historical perspective to provide context for a critical evaluation of factors influencing the outcomes of randomized controlled trials (RCTs); including sample populations, outcome measures, TENS techniques, and comparator interventions. Three possibilities are offered to resolve the impasse. Firstly, to conduct large multi-centered RCTs using an enriched enrolment with randomized withdrawal design, that incorporates a 'run-in phase' to screen for potential TENS responders and to optimise TENS treatment according to individual need. Secondly, to meta-analyze published RCT data, irrespective of type of pain, to determine whether TENS reduces the intensity of pain during stimulation, and to include a detailed assessment of levels of certainty and precision. Thirdly, to concede that it may be impossible to determine efficacy due to insurmountable methodological, logistical and financial challenges. The consequences to clinicians, policy makers and funders of this third scenario are discussed. I argue that patients will continue to use TENS irrespective of the views of clinicians, policy makers, funders or guideline panel recommendations, because TENS is readily available without prescription; TENS generates a pleasant sensory experience that is similar to easing pain using warming and cooling techniques; and technological developments such as smart wearable TENS devices will improve usability in the future. Thus, research is needed on how best to integrate TENS into existing pain management strategies by analyzing data of TENS usage by expert-patients in real-world settings.

Effect of Acupuncture on the p38 Signaling Pathway in Several Nervous System Diseases: A Systematic Review

Acupuncture is clinically used to treat various diseases and exerts positive local and systemic effects in several nervous system diseases. Advanced molecular and clinical studies have continually attempted to decipher the mechanisms underlying these effects of acupuncture. While a growing understanding of the pathophysiology underlying several nervous system diseases shows it to be related to inflammation and impair cell regeneration after ischemic events, the relationship between the therapeutic mechanism of acupuncture and the p38 MAPK signal pathway has yet to be elucidated. This review discusses the latest advancements in the identification of the effect of acupuncture on the p38 signaling pathway in several nervous system diseases. We electronically searched databases including PubMed, Embase, and the Cochrane Library from their inception to April 2020, using the following keywords alone or in various combinations: "acupuncture", "p38 MAPK pathway", "signaling", "stress response", "inflammation", "immune", "pain", "analgesic", "cerebral ischemic injury", "epilepsy", "Alzheimer's disease", "Parkinson's disease", "dementia", "degenerative", and "homeostasis". Manual acupuncture and electroacupuncture confer positive therapeutic effects by regulating proinflammatory cytokines, ion channels, scaffold proteins, and transcription factors including TRPV1/4, Nav, BDNF, and NADMR1; consequently, p38 regulates various phenomena including cell communication, remodeling, regeneration, and gene expression. In this review article, we found the most common acupoints for the relief of nervous system disorders including GV20, GV14, ST36, ST37, and LI4. Acupuncture exhibits dual regulatory functions of activating or inhibiting different p38 MAPK pathways, contributing to an overall improvement of clinical symptoms and function in several nervous system diseases.

Investigation of the Involvement of the Endocannabinoid System in TENS-Induced Antinociception

Transcutaneous electrical nerve stimulation (TENS) promotes antinociception by activating the descending pain modulation pathway and consequently releasing endogenous analgesic substances. In addition, recent studies have shown that the endocannabinoid system controls pain. Thus, the present study investigated the involvement of the endocannabinoid system in TENS-induced antinociception of cancer pain using a cancer pain model induced by intraplantar (i.pl.) injections of Ehrlich tumor cells in male Swiss mice. Low- and high-frequency TENS was applied for 20 minutes to the mice's paws, and to investigate the involvement of the endocannabinoid system were used the N-(peperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pitazole-3-carboixamide (AM251), a cannabinoid CB₁ receptor antagonist and (5Z,8Z,11Z,14Z)-5,8,11,14-eicosatetraenyl-methylester phosphonofluoridic acid (MAFP), an inhibitor of the endocannabinoid metabolizing enzyme fatty acid amide hydrolase, injected by via i.pl., intrathecal (i.t.), and intradorsolateral periaqueductal gray matter (i.dl.PAG). Furthermore, liquid chromatography-tandem mass spectrometry, western blot, and immunofluorescence assays were used to evaluate the endocannabinoid anandamide levels, cannabinoid CB₁ receptor protein levels, and cannabinoid CB₁ receptor immunoreactivity, respectively. Low- and high-frequency TENS reduced the mechanical allodynia induced by Ehrlich tumor cells and this effect was reversed by AM251 and potentiated by MAFP at the peripheral and central levels. In addition, TENS increased the endocannabinoid anandamide levels and the cannabinoid CB₁ receptor protein levels and immunoreactivity in the paw, spinal cord, and dorsolateral periaqueductal gray matter. These results suggest that low- and high-frequency TENS is effective in controlling cancer pain, and the endocannabinoid system is involved in this effect at both the peripheral and central levels. PERSPECTIVE: TENS is a nonpharmacological strategy that may be used to control cancer pain. Identification of a new mechanism involved in its analgesic effect could lead to the development of clinical studies as well as an increase in its application, lessening the need for pharmacological treatments.

Critical Care Pain Management in Patients Affected by the Opioid Epidemic: A Review

The rapid rise in the opioid epidemic has had a deleterious impact across the United States. This increase has drawn the attention of the critical care community not only because of the surge in acute opioid overdose-related admissions, but also due to the increase in the number of opioid-dependent and opioid-tolerant patients being treated in the intensive care unit (ICU). Opioid-related issues relevant to the critical care physician include direct care of patients with opioid overdoses, the provision of sufficient analgesia to patients with opioid dependence and tolerance, and the task of preventing long-term opioid dependence in patients who survive ICU care. This review identifies the challenges facing the ICU physician working with patients presenting with opioid-related complications, discusses current solutions, and suggests future areas of research and heightened ICU clinician attention.

Coping with Phantom Limb Pain

Phantom limb pain is a chronic neuropathic pain that develops in 45-85% of patients who undergo major amputations of the upper and lower extremities and appears predominantly during two time frames following an amputation: the first month and later about 1 year. Although in most patients the frequency and intensity of pain diminish over time, severe pain persists in about 5-10%. It has been proposed that factors in both the peripheral and central nervous systems play major roles in triggering the development and maintenance of pain associated with extremity amputations. Chronic pain is physically and mentally debilitating, affecting an individual's capacity for self-care, but also diminishing an individual's daily capacity for personal and economic independence. In addition, the pain may lead to depression and feelings of hopelessness. A National Center for Biotechnology Information study found that in the USA alone, the annual cost of dealing with neuropathic pain is more than $600 billion, with an estimated 20 million people in the USA suffering from this condition. Although the pain can be reduced by antiepileptic drugs and analgesics, they are frequently ineffective or their side effects preclude their use. The optimal approach for eliminating neuropathic pain and improving individuals' quality of life is the development of novel techniques that permanently prevent the development and maintenance of neuropathic pain, or that eliminate the pain once it has developed. What is still required is understanding when and where an effective novel technique must be applied, such as onto the nerve stump of the transected peripheral axons, dorsal root ganglion neurons, spinal cord, or cortex to induce the desired influences. This review, the second of two in this journal volume, examines the techniques that may be capable of reducing or eliminating chronic neuropathic pain once it has developed. Such an understanding will improve amputees' quality of life by blocking the mechanisms that trigger and/or maintain PLP and chronic neuropathic pain.

Low-intensity muscle contraction exercise following the onset of arthritis improves hyperalgesia via reduction of joint inflammation and central sensitization in the spinal cord in a rat model

We examined the effect of immobilization, low-intensity muscle contraction exercise, and transcutaneous electrical nerve stimulation (TENS) on tissue inflammation and acute pain following the onset of arthritis in a rat model. Sixty Wistar rats were divided into five groups: (1) Arthritis group, (2) arthritis and immobilization (Immobilization group), (3) arthritis and low intensity muscle contraction (Exercise group), (4) arthritis and TENS (TENS group), and (5) sham arthritis (Sham group). Arthritis was induced in the right knee joints by single injection of 3% kaolin and carrageenan. Immobilization of the right hindlimb was conducted by full extension of the right knee joints and full plantar flexion of the ankle joints using a plaster cast for 7 days after injection. The right quadriceps muscles were subjected to electrical stimulation (frequency: 50 Hz; intensity: 2-3 mA) for 20 min/day as contraction exercise for one week. TENS was delivered at 20 min/day for one week (frequency: 50 Hz; intensity: 1 mA). The pressure pain threshold (PPT) and paw withdrawal response (PWR) were evaluated at 1 and 7 days after injection. We also analyzed the number of CD68-positive cells in the synovium by immunohistochemistry and determined the expression level of calcitonin gene-related peptide (CGRP) in the spinal dorsal horn with immunofluorescence. Improvements of both PPT and PWR were observed in the Exercise group at 7 days after injection compared to those of the Arthritis and Immobilization groups, although only improvement of PPT was observed in the TENS group. The number of CD68-positive cells in the synovium and CGRP expression in the dorsal horn decreased only in the Exercise group. These results suggested that low-intensity muscle contraction exercise might be a better treatment for reduction of arthritis-induced inflammation and acute pain compared to immobilization and TENS.

Immediate effects of transcutaneous electrical nerve stimulation (TENS) administered during resistance exercise on pain intensity and physical performance of healthy subjects: a randomized clinical trial

PURPOSE

Exercise-induced muscle pain is a self-limiting condition which impacts physical activity habits. Transcutaneous electrical nerve stimulation (TENS) promotes pain reduction and functional improvement in different pain conditions. We propose that applying TENS during exercise might reduce pain and improve physical performance. Thus, we aimed to investigate immediate effects of TENS applied during resistance exercise.

METHODS

Healthy subjects of both sexes, irregularly active or sedentary were assigned into two groups: active (n = 24) or placebo (n = 22) TENS. The study was conducted over five moments: on day 0, subjects were recruited, on day 1 subjects performed the one-repetition maximum test (1RM); 72 h later, on day 2, 1RM was retested; 48 h later, on day 3, TENS was applied during a functional-resisted exercise protocol for upper limbs (bench press and rowing), with an intensity of 80% of 1RM; and 24 h after, on day 4, subjects were reevaluated. Assessment included pain intensity at rest and with movement, pressure pain thresholds, and muscle fatigue.

RESULTS

TENS did not reduce pain intensity when compared to placebo (p > 0.05). TENS reduce PPT in the latissmus dorsi: p = 0.02 and anterior tibialis: p = 0.04 in immediate reassessment. Immediate effects of TENS were significant for fatigue perception at rest (p = 0.01) and number of maximum repetitions during exercise sets, starting from the 5th set of rowing exercise (p = 0.002).

CONCLUSION

Our results show that TENS did not reduce pain perception in healthy individuals, but its use induced increased muscle action, contributing to a greater fatigue perception.

A Mechanism-Based Approach to Physical Therapist Management of Pain

Pain reduction is a primary goal of physical therapy for patients who present with acute or persistent pain conditions. The purpose of this review is to describe a mechanism-based approach to physical therapy pain management. It is increasingly clear that patients need to be evaluated for changes in peripheral tissues and nociceptors, neuropathic pain signs and symptoms, reduced central inhibition and enhanced central excitability, psychosocial factors, and alterations of the movement system. In this Perspective, 5 categories of pain mechanisms (nociceptive, central, neuropathic, psychosocial, and movement system) are defined, and principles on how to evaluate signs and symptoms for each mechanism are provided. In addition, the underlying mechanisms targeted by common physical therapist treatments and how they affect each of the 5 categories are described. Several different mechanisms can simultaneously contribute to a patient's pain; alternatively, 1 or 2 primary mechanisms may cause a patient's pain. Further, within a single pain mechanism, there are likely many possible subgroups. For example, reduced central inhibition does not necessarily correlate with enhanced central excitability. To individualize care, common physical therapist interventions, such as education, exercise, manual therapy, and transcutaneous electrical nerve stimulation, can be used to target specific pain mechanisms. Although the evidence elucidating these pain mechanisms will continue to evolve, the approach outlined here provides a conceptual framework for applying new knowledge as advances are made.

Transcutaneous electrical nerve stimulation for postoperative pain relief after arthroscopic rotator cuff repair: a prospective double-blinded randomized trial

BACKGROUND

Arthroscopic rotator cuff repair (ARCR) can be associated with significant postoperative pain. Concern for opioid abuse has led surgeons to identify alternative, efficacious methods of postoperative analgesia. To determine whether transcutaneous electrical nerve stimulation (TENS) can have a similarly beneficial effect after shoulder procedures, we conducted a prospective double-blinded randomized trial in patients undergoing outpatient ARCR.

METHODS

All patients undergoing ARCR of a full-thickness rotator cuff tear by the senior authors were identified. Patients with a history of recent narcotic use or prior narcotic abuse and those under management of a pain control specialist were excluded. Patients were randomized into 2 groups, active or placebo TENS, and used the device for 4 sessions/day for 45 minutes/session for the first postoperative week. All patients received Percocet 5/325 mg (oxycodone/acetaminophen) for use as rescue pain pills. One-week narcotic consumption and visual analog scale pain scores were compared between groups.

RESULTS

The final analysis included 37 patients (21 active,16 placebo). Baseline and procedural differences were not different between groups. At 1 week postoperatively, patients in the active group had significantly lower pain scores (3.6 ± 2.1 vs. 5.8 ± 1.2; P= .008). Postoperative Percocet consumption during the initial 48 hours (12.8 ± 4.7 vs. 17.2 ± 6.3; P = .020) and during the first week (25.2 ± 9.9 vs. 33.8 ± 14.3; P = .037) was also significantly lower in the active group.

CONCLUSION

Results from this prospective double-blinded randomized trial demonstrate that compared with placebo TENS, active TENS can result in significantly less pain and reduced opioid use in the immediate postoperative period after ARCR, suggesting that TENS may be potentially useful in a multimodal approach to managing postoperative pain.

Does electrode placement influence tens-induced antihyperalgesia in experimental inflammatory pain model?

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This study challenges the notion that TENS can only be applied at the site of pain.

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The study supports the use of TENS in patients with significant skin injuries.

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This helps to understand the action of TENS in edema.

Background

Transcutaneous electrical nerve stimulation (TENS) is a treatment commonly used for managing pain; however, the ideal placement of the electrodes is not fully understood.

Objective

To investigate the best way to apply TENS electrodes in an experimental inflammatory pain model.

Method

Knee joint inflammation was induced in rats, followed by administration of low-frequency TENS (4 Hz) under anesthesia for five days. Animals were randomly allocated to five groups according to electrode placement (n = 6, each): dermatome, contralateral, paraspinal, acupoint, and control. Interventions: Low-frequency TENS at sensory intensity and 100 μs pulse duration. Withdrawal thresholds to mechanical (von Frey) and thermal stimuli and joint edema were assessed before induction of inflammation and immediately before and after application of TENS.

Results

Reduced paw withdrawal threshold and thermal latency that occur 24 h after the induction of inflammation were significantly reversed by the administration of TENS in all groups when compared with sham treatment or with the condition before TENS treatment. No difference was observed in the edema measurement.

Conclusion

These results offer more options for practitioners to choose the area of the body most commodious for electrode placement, depending on the clinical condition of the patient, because the effect was similar at all sites. In addition, there was a loss of the effectiveness of TENS in reversing mechanical and thermal hyperalgesia on the fifth day, suggesting the development of the tolerance phenomenon.

TENS effects on dysesthesia and quality of life after breast cancer surgery with axilectomy: randomized controlled trial

Abstract Introduction: After breast cancer surgery, many women may present quality of life (QOL) impairment due to the presence of discomfort as dysesthesia in the anterolateral region of the chest, armpit and/or medial part of the arm caused by intercostobrachial nerve injury (ICBN). Objective: To investigate the effects of Transcutaneous Electrical Nerve Stimulation (TENS) on dysesthesia intensity at the intercostobrachial nerve (ICBN) dermatome and QOL in women after breast cancer surgery. Methods: A randomized, double-blinded, placebo controlled clinical trial was conducted. Women undergoing axillary lymphadenectomy (AL), with dysesthesia on ICBN dermatome were included. Patients were divided into active and placebo TENS groups. TENS was applied with a frequency of 100 Hz, pulse duration of 100 µs and amplitude at the highest sensory intensity tolerable for 20 minutes during 20 sessions, three times a week, on alternating days. In the placebo TENS group, electrical current was delivered only during the first 45 seconds of application. Skin sensitivity was assessed by esthesiometry. Dysesthesia intensity was assessed with a visual analogue scale (VAS) and QOL with the EORTC QLQ-C30 and the specific EORTC QLQ-BR23 which is the Breast Cancer Module. Results: VAS decreased significantly over the 20 sessions in the active TENS group (p<0.006) and no difference was found between groups. There weren’t significant differences in EORTC QLQ-C30 and EORTC QLQ-BR23 after 20 sessions or between groups. Conclusion: TENS decreased dysesthesia intensity in the ICBN dermatome after breast cancer surgery, but did not improve quality of life.

Analgesia in the surgical intensive care unit

Critically ill patients are a heterogeneous group with diverse comorbidities and physiological derangements. The management of pain in the critically ill population is emerging as a standard of care in the intensive care unit (ICU). Pain control of critically ill patients in the ICU presents numerous challenges to intensivists. Inconsistencies in pain assessment, analgesic prescription and variation in monitoring sedation and analgesia result in suboptimal pain management. Inadequate pain control can have deleterious effects on several organ systems in critically ill patients. Therefore, it becomes incumbent on physicians and nurses caring for these patients to carefully evaluate their practice on pain management and adopt an optimal pain management strategy that includes a reduction in noxious stimuli, adequate analgesia and promoting education regarding sedation and analgesia to the ICU staff. Mechanistic approaches and multimodal analgesic techniques have been clearly demonstrated to be the most effective pain management strategy to improve outcomes. For example, recent evidence suggests that the use of short acting analgesics and analgesic adjuncts for sedation is superior to hypnotic based sedation in intubated patients. This review will address analgesia in the ICU, including opioid therapy, adjuncts, regional anaesthesia and non-pharmacological options that can provide a multimodal approach to treating pain.

Immediate and short-term effects of the combination of dry needling and percutaneous TENS on post-needling soreness in patients with chronic myofascial neck pain

Background

Dry needling (DN) and percutaneous electrical nerve stimulation (PENS) are widely used techniques in the treatment of myofascial pain.

Objective

To investigate the immediate and short-term effects of the combination of DN and PENS compared to DN alone on the upper trapezius muscle.

Method

This is a 72-hour follow-up single-blinded randomized controlled trial. Sixty-two volunteer patients with chronic myofascial neck pain with active Myofascial Trigger Points (MTrPs) in the upper trapezius muscle were recruited. Randomization was performed, and 31 patients received DN treatment (DN group) and 31 received DN and PENS (DN+PENS group). The primary outcomes were neck disability index (NDI) and visual analog scale for pain for both post-needling soreness (PNS) and neck pain intensity (NPI). Pressure pain threshold (PPT) and cervical range of motion (CROM) were the secondary outcomes.

Results

We detected between-group differences in NPI and PNS in favor of the DN+PENS group immediately after treatment. No between-group differences in NDI were observed.

Conclusion

PENS application after dry needling treatment is more effective than dry needling alone for decreasing soreness in the short term and improving neck pain intensity immediately in patients with myofascial chronic neck pain.

The use of conventional transcutaneous electrical nerve stimulation in chronic facial myalgia patients

OBJECTIVES

The aim of this study was to evaluate the efficacy of conventional TENS in women affected by chronic facial myalgia.

MATERIALS AND METHODS

The study was performed on 49 women affected by chronic facial myalgia randomly allocated in the TENS group (34 women) and the control group (15 women). The subjective level of pain was assessed by the Visual Analogue Scale indicating the mean (VAS MEAN), the maximum (VAS MAX) and the current intensity of pain (VAS NOW). The level of pain at the muscular palpation sites was assessed by the Pericranial Muscle Tenderness Score (PTS) and the Cervical Muscle Tenderness Score (CTS). The TENS therapy lasted for 10 weeks, and data were collected at baseline, after 5, 10, 15 and 25 weeks. The differences between groups before and after treatment were compared with the Mann-Whitney and the Kolmogorov-Smirnov tests. The intra-group differences were compared with the one-way ANOVA test.

RESULTS

The results showed that the VAS MEAN, VAS MAX, PTS and CTS were significantly reduced in the TENS group compared to the control group after 10 weeks of TENS (p < 0.05). The intra-group analysis revealed a decreasing tendency of VAS MEAN, VAS MAX, VAS NOW, PTS and CTS in the TENS group in a 25-week period (p < 0.05).

CONCLUSIONS

The study demonstrated the efficacy of conventional TENS in patients with chronic facial myalgia and the decrease in both subjective and objective pain.

CLINICAL RELEVANCE

Conventional TENS is a safe, non-invasive, easy-to-administer therapy for chronic facial myalgia.

Effects of Noxious Electrical Stimulation and Eccentric Exercise on Pain Sensitivity in Asymptomatic Individuals

BACKGROUND

Achilles tendinopathy is a common overuse injury in running and jumping athletes. Currently, we do not understand why some conservative interventions (eg, noxious electrical stimulation and eccentric training) may reduce the pain associated with tendinopathy.

OBJECTIVE

To determine whether noxious electrical stimulation (NES) or eccentric contractions would alter pain sensitivity around the asymptomatic Achilles tendon.

DESIGN

A double-blind trial with block-randomization by gender into 3 intervention arms: NES, eccentric contractions, or low-intensity cycling.

PARTICIPANTS

A total of 40 volunteers with no current pain conditions started the study, and 39 completed follow-up testing.

METHODS

Participants underwent 2 baseline sessions to assess pain sensitivity response stability of pressure pain threshold (PPT), heat pain threshold (HPT), and heat temporal summation (HTS) over the Achilles tendon. Immediately after the second baseline session, participants performed 1 session of an intervention and were tested immediately postintervention and the next morning. Eccentric-only plantarflexor exercise was performed (4 sets of 15 repetitions) using full bodyweight and slow, 5-second contractions. Noxious electrical stimulation was applied to the Achilles for 20 minutes and dosed to the subjects' pain tolerance. Low-intensity cycling was dosed (60-70 W for 20 minutes) to minimize occurrence of exercise-induced hypoalgesia. The PPT was the primary outcome measure.

RESULTS

For PPT, both NES (P < .001) and eccentric (P = .003) groups were less sensitive to pressure immediately posttreatment, and the eccentric group maintained this effect through the next morning (P = .043). No group differences were seen for HPT, but the NES (P = .031) and eccentric (P = .036) groups had less HTS the next morning.

CONCLUSIONS

A single session of eccentric exercise and NES can produce immediate and next-day reductions in pain sensitivity in asymptomatic adults. The immediacy of these effects points toward a neurophysiologic mechanism. Future research needs to be performed in clinical populations and to assess any cumulative effects to repetitive intervention.

Using TENS for pain control: the state of the evidence

Transcutaneous electrical nerve stimulation (TENS) is a nonpharmacological intervention that activates a complex neuronal network to reduce pain by activating descending inhibitory systems in the central nervous system to reduce hyperalgesia. The evidence for TENS efficacy is conflicting and requires not only description but also critique. Population-specific systemic reviews and meta-analyses are emerging, indicating both HF and LF TENS being shown to provide analgesia, specifically when applied at a strong, nonpainful intensity. The purpose of this article is to provide a critical review of the latest basic science and clinical evidence for TENS. Additional research is necessary to determine if TENS has effects specific to mechanical stimuli and/or beyond reduction of pain and will improve activity levels, function and quality of life.

The New Portable Transcutaneous Electrical Nerve Stimulation Device Was Efficacious in the Control of Primary Dysmenorrhea Cramp Pain

INTRODUCTION

Transcutaneous electrical nerve stimulation (TENS) is an established method for pain relief in dysmenorrhea. A feasible advantage would be the study of a portable device. The purpose of the study was to evaluate the effectiveness and safety of a new portable TENS device (TANYX®) for menstruation cramps.

MATERIALS AND METHODS

Forty women were evaluated in a double-blind, prospective, randomized fashion, divided into sham and active groups. TENS was applied medially at the suprapubic region, for 30-min duration at eight-hour intervals, up to seven days. The placebo group (PG) received sham device. The TENS group (TG) applied an active 85 Hz frequency TENS. Efficacy measures were pain relief evaluated on a visual analog scale (VAS) and diclofenac intake, and quality of life represented by: 1) capacity to get out of the bed, 2) food or drink intake, 3) missing routine daily activities such as work or school, and 4) quality of sleep.

RESULTS

The active TENS device induced a prompt onset of pain relief in a strictly segmental manner nearby the dermatomes where the TENS was applied at the skin, and there was a drop in mean pain score from 8 to 2 cm (p < 0.001). Diclofenac consumption was also significantly reduced (p < 0.01), compared with the PG. Quality of life improved significantly in TG when compared with PG (p < 0.05). Three months after the beginning of the study, 14/20 of the women were still using the active device regularly. No adverse effects were observed.

CONCLUSIONS

The portable, disposable, active TENS device induced a prompt onset of pain relief and improved the quality of life, without adverse effects, in patients with painful cramps associated with dysmenorrhea.

Transcutaneous electrical nerve stimulation for the control of pain during rehabilitation after total knee arthroplasty: A randomized, blinded, placebo-controlled trial

This study evaluated the efficacy of transcutaneous electrical nerve stimulation (TENS) in reducing pain and hyperalgesia and increasing function after total knee arthroplasty (TKA). We hypothesized that participants using TENS during rehabilitation exercises would report significantly lower pain during range-of-motion (ROM) activity and fast walking but not at rest, would have less hyperalgesia, and would have better function than participants receiving placebo-TENS or standard care. We also hypothesized that change in ROM pain would differ based on psychological characteristics (trait anxiety, pain catastrophizing, and depression) and treatment group. This prospective, randomized study used intent-to-treat analyses in 317 participants after primary, unilateral TKA. Assessors, blinded to treatment allocation, measured pain, function (ROM and gait speed), and hyperalgesia (quantitative sensory tests) postoperatively and 6 weeks after surgery. Analgesic intake, anxiety, depression, and pain catastrophizing were also assessed. TENS participants used it 1 to 2 times per day at 42 mA (on average) and had less pain postoperatively during active knee extension (P=.019) and fast walking (P=.006) than standard care participants. TENS and placebo-TENS were not significantly different. TENS participants who scored low on anxiety and pain catastrophizing had a greater reduction in ROM pain at 6 weeks than those who scored high on these factors (P=.002 and P=.03). Both TENS and placebo-TENS participants had less postoperative mechanical hyperalgesia (P=.03-.01) than standard care participants. Supplementing pharmacologic analgesia with TENS during rehabilitation exercises reduces movement pain postoperatively, but a placebo influence exists and the effect is gone by 6 weeks. Patients with low anxiety and pain catastrophizing may benefit most from TENS.

A selective α2 B adrenoceptor agonist (A-1262543) and duloxetine modulate nociceptive neurones in the medial prefrontal cortex, but not in the spinal cord of neuropathic rats

BACKGROUND

The noradrenergic system contributes to pain modulation, but the roles of its specific adrenoceptors are still being defined. We have identified a novel, potent (rat EC50  = 4.3 nM) and selective α2B receptor agonist, A-1262543, to further explore this adrenoceptor subtype's contribution to pathological nociception.

METHODS

Systemic administration of A-1262543 (1-10 mg/kg, intraperitoneal) dose-dependently attenuated mechanical allodynia in animals with a spinal nerve ligation injury. To further explore its mechanism of action, the activity of nociceptive neurones in the spinal cord and medial prefrontal cortex (mPFC) were examined after injection of 3 mg/kg of A-1262543 (intravenous, i.v.). These effects were compared with duloxetine (3 mg/kg, i.v.), a dual noradrenaline (NA) and serotonin (5-HT) reuptake inhibitor.

RESULTS

Systemic administration of A-1262543 or duloxetine did not alter the spontaneous or evoked firing of spinal wide dynamic range and nociceptive-specific neurones in the neuropathic rats, indicating that neither compound engaged spinal, peripheral or descending pathways. In contrast to the lack of effect on spinal neurones, both A-1262543 and duloxetine reduced the evoked and spontaneous firing of 'pain-responsive' (PR) neurones in the mPFC. Duloxetine, but not A-1262543, also inhibited the firing of pain non-responsive (nPR) neurones in the mPFC probably reflecting duloxetine's contribution to modulating non-pain endpoints.

CONCLUSIONS

These data highlight that activation of the α2B adrenoceptor as well as inhibiting NA and 5-HT reuptake can result in modulating the ascending nociceptive system, and in particular, dampening the firing of PR neurones in the mPFC.

Acupuncture for Pediatric Pain

Chronic pain is a growing problem in children, with prevalence as high as 30.8%. Acupuncture has been found to be useful in many chronic pain conditions, and may be of clinical value in a multidisciplinary treatment program. The basic principles of acupuncture are reviewed, as well as studies exploring basic mechanisms of acupuncture and clinical efficacy. Conditions commonly treated in the pediatric pain clinic, including headache, abdominal pain, fibromyalgia, juvenile arthritis, complex regional pain syndrome, cancer pain, as well as perioperative pain studies are reviewed and discussed. Areas in need of further research are identified, and procedural aspects of acupuncture practice and safety studies are reviewed. Acupuncture can be an effective adjuvant in the care of pediatric patients with painful conditions, both in a chronic and an acute setting. Further studies, including randomized controlled trials, as well as trials of comparative effectiveness are needed.

Effects of different frequencies of transcutaneous electrical nerve stimulation on venous vascular reactivity

Transcutaneous electrical nerve stimulation (TENS) is a type of therapy used primarily for analgesia, but also presents changes in the cardiovascular system responses; its effects are dependent upon application parameters. Alterations to the cardiovascular system suggest that TENS may modify venous vascular response. The objective of this study was to evaluate the effects of TENS at different frequencies (10 and 100 Hz) on venous vascular reactivity in healthy subjects. Twenty-nine healthy male volunteers were randomized into three groups: placebo (n=10), low-frequency TENS (10 Hz, n=9) and high-frequency TENS (100 Hz, n=10). TENS was applied for 30 min in the nervous plexus trajectory from the superior member (from cervical to dorsal region of the fist) at low (10 Hz/200 μs) and high frequency (100 Hz/200 μs) with its intensity adjusted below the motor threshold and intensified every 5 min, intending to avoid accommodation. Venous vascular reactivity in response to phenylephrine, acetylcholine (endothelium-dependent) and sodium nitroprusside (endothelium-independent) was assessed by the dorsal hand vein technique. The phenylephrine effective dose to achieve 70% vasoconstriction was reduced 53% (P<0.01) using low-frequency TENS (10 Hz), while in high-frequency stimulation (100 Hz), a 47% increased dose was needed (P<0.01). The endothelium-dependent (acetylcholine) and independent (sodium nitroprusside) responses were not modified by TENS, which modifies venous responsiveness, and increases the low-frequency sensitivity of α1-adrenergic receptors and shows high-frequency opposite effects. These changes represent an important vascular effect caused by TENS with implications for hemodynamics, inflammation and analgesia.

Transcutaneous electrical nerve stimulation and conditioned pain modulation influence the perception of pain in humans

BACKGROUND

Research in animal models suggests that transcutaneous electrical nerve stimulation (TENS) and conditioned pain modulation (CPM) produce analgesia via two different supraspinal pathways. No known studies have examined whether TENS and CPM applied simultaneously in human subjects will enhance the analgesic effect of either treatment alone. The purpose of the current study was to investigate whether the simultaneous application of TENS and CPM will enhance the analgesic effect of that produced by either treatment alone.

METHODS

Sixty healthy adults were randomly allocated into two groups: (1) CPM plus active TENS; (2) CPM plus placebo TENS. Pain threshold for heat (HPT) and pressure (PPT) were recorded from subject's left forearm at baseline, during CPM, during active or placebo TENS, and during CPM plus active or placebo TENS. CPM was induced by placing the subjects' contralateral arm in a hot water bath (46.5 °C) for 2 min. TENS (100 μs, 100 Hz) was applied to the forearm for 20 min at a strong but comfortable intensity.

RESULTS

Active TENS alone increased PPT (but not HPT) more than placebo TENS alone (p = 0.011). Combining CPM and active TENS did not significantly increase PPT (p = 0.232) or HPT (p = 0.423) beyond CPM plus placebo TENS. There was a significant positive association between PPT during CPM and during active TENS (r(2)  = 0.46; p = 0.003).

CONCLUSIONS

TENS application increases PPT; however, combining CPM and TENS does not increase the CPM's hypoalgesic response. CPM effect on PPT is associated with the effects of TENS on PPT.

High-frequency transcutaneous electrical nerve stimulation reduces pain and cardio-respiratory parameters in an animal model of acute pain: participation of peripheral serotonin

The objective of this study was to investigate the effect of high-frequency transcutaneous electrical nerve stimulation (HF-TENS) in antihyperalgesia, assessed through changes of sciatic nerve activity and its effects on cardiorespiratory parameters, using formalin-induced nociception in anesthetized rats. The animals were divided into formalin (FORM) and HF-TENS groups. All rats received injections of 5% formalin (50 μl, right hind-paw). The sciatic nerve activity and cardiopulmonary parameters (mean arterial pressure, heart rate, and respiratory frequency) were measured, and then the serum levels of serotonin (5-HT) were determined by an enzyme-linked immunosorbent assay kit. The formalin injection was able to increase the sciatic nerve activity, heart rate, and respiratory frequency. The treatment with HF-TENS significantly reduced the sciatic nerve activity and respiratory frequency 20 minutes after formalin injection and was able to increase serum 5-HT. Furthermore, when comparing the groups, reductions in the mean arterial pressure, heart rate, respiratory frequency, and sciatic nerve activity were shown at different times. Thus, we concluded that HF-TENS was capable of inducing analgesia, which was most likely related to increased serotonin release. Moreover, we demonstrated that TENS was able to block the adverse cardiovascular and respiratory changes induced by pain. Further neurophysiological studies are necessary to clarify the intrinsic mechanisms underlying HF-TENS-induced analgesia.

Pain relief by transcutaneous electric nerve stimulation with bidirectional modulated sine waves in patients with chronic back pain: a randomized, double-blind, sham-controlled study

Objectives.  Newly developed bidirectional modulated sine waves (BMW) might provide some derived benefit to patients with low back pain. Pain relief by transcutaneous electric nerve stimulation (TENS) with BMWs was tested. Materials and Methods.  Analgesic effects of BMWs and conventional bidirectional pulsed waves on chronic back pain in 28 patients were compared, and effects of repeated TENS using BMWs on chronic back pain were investigated in 21 patients by means of a randomized double-blind, sham-controlled, parallel-group method. Pain intensity was assessed using numerical rating scale (NRS). Results.  There was significant immediate reduction in NRS in patients receiving BMWs, and 60 min after treatment compared to sham TENS. Weekly repeated treatments using massage and TENS with BMWs for 5 weeks resulted in a decrease of NRS, but there were no significant differences between the TENS plus massage and sham TENS plus massage groups. Conclusions.  This study shows that TENS with BMWs significantly inhibits chronic back pain, and treatment effects are attained within a day. The results also suggest that there were no statistically significant long-term effects of TENS with BMW in the repeated treatment.

Temporal regularity determines the impact of electrical stimulation on tactile reactivity and response to capsaicin in spinally transected rats

Nociceptive plasticity and central sensitization within the spinal cord depend on neurobiological mechanisms implicated in learning and memory in higher neural systems, suggesting that the factors that impact brain-mediated learning and memory could modulate how stimulation affects spinal systems. One such factor is temporal regularity (predictability). The present paper shows that intermittent hindleg shock has opposing effects in spinally transected rats depending upon whether shock is presented in a regular or irregular (variable) manner. Variable intermittent legshock (900 shocks) enhanced mechanical reactivity to von Frey stimuli (hyperreactivity), whereas 900 fixed-spaced legshocks produced hyporeactivity. The impact of fixed-spaced shock depended upon the duration of exposure; a brief exposure (36 shocks) induced hyperreactivity whereas an extended exposure (900 shocks) produced hyporeactivity. The enhanced reactivity observed after variable shock was most evident 60-180 min after treatment. Fixed and variable intermittent stimulation applied to the sciatic nerve, or the tail, yielded a similar pattern of results. Stimulation had no effect on thermal reactivity. Exposure to fixed-spaced shock, but not variable shock, attenuated the enhanced mechanical reactivity (EMR) produced by treatment with hindpaw capsaicin. The effect of fixed-spaced stimulation lasted 24h. Treatment with fixed-spaced shock also attenuated the maintenance of capsaicin-induced EMR. The results show that variable intermittent shock enhances mechanical reactivity, while an extended exposure to fixed-spaced shock has the opposite effect on mechanical reactivity and attenuates capsaicin-induced EMR.

Acid-sensing ion channel 3 mediates peripheral anti-hyperalgesia effects of acupuncture in mice inflammatory pain

Background

Peripheral tissue inflammation initiates hyperalgesia accompanied by tissue acidosis, nociceptor activation, and inflammation mediators. Recent studies have suggested a significantly increased expression of acid-sensing ion channel 3 (ASIC3) in both carrageenan- and complete Freund's adjuvant (CFA)-induced inflammation. This study tested the hypothesis that acupuncture is curative for mechanical hyperalgesia induced by peripheral inflammation.

Methods

Here we used mechanical stimuli to assess behavioral responses in paw and muscle inflammation induced by carrageenan or CFA. We also used immunohistochemistry staining and western blot methodology to evaluate the expression of ASIC3 in dorsal root ganglion (DRG) neurons.

Results

In comparison with the control, the inflammation group showed significant mechanical hyperalgesia with both intraplantar carrageenan and CFA-induced inflammation. Interestingly, both carrageenan- and CFA-induced hyperalgesia were accompanied by ASIC3 up-regulation in DRG neurons. Furthermore, electroacupuncture (EA) at the ST36 rescued mechanical hyperalgesia through down-regulation of ASIC3 overexpression in both carrageenan- and CFA-induced inflammation.

Conclusions

In addition, electrical stimulation at the ST36 acupoint can relieve mechanical hyperalgesia by attenuating ASIC3 overexpression.

Transcutaneous electrical nerve stimulation for the management of painful conditions: focus on neuropathic pain

The management of neuropathic pain is challenging, with medication being the first-line treatment. Transcutaneous electrical nerve stimulation (TENS) is an inexpensive, noninvasive, self-administered technique that is used as an adjunct to medication. Clinical experience suggests that TENS is beneficial providing it is administered at a sufficiently strong intensity, close to the site of pain. At present, there are too few randomized controlled trials on TENS for neuropathic pain to judge effectiveness. The findings of systematic reviews of TENS for other pain syndromes are inconclusive because trials have a low fidelity associated with inadequate TENS technique and infrequent treatments of insufficient duration. The use of electrode arrays to spatially target stimulation more precisely may improve the efficacy of TENS in the future.

Evaluation of Transcutaneous Electrical Nerve Stimulation as a Treatment of Neck Pain due to Musculoskeletal Disorders

BACKGROUND

This study was designed to evaluate transcutaneous electrical nerve stimulation (TENS) as a treatment for neck pain due to musculoskeletal disorders within the context of a physiotherapy treatment.

METHODS

Thirty subjects with neck pain were randomly allocated to two groups, treated with either TENS (n = 15) or placebo (n = 15). Each subject received one session for one hour. All subjects were evaluated before, during treatment, after switch off and again a week after by using Myometer machine. All subjects completed the follow-up assessment. Subjects referred for out-subjects' physiotherapy department, fulfilling the inclusion and exclusion criteria, took part in the study.

RESULTS

The assessments were compared and used to measure outcome treatment. Improvement in their condition was measured in terms of a reduction in the individual's level of pain during the week after the end of the first session. At the end of the first session, the study showed that 11 subjects (73%) in the treatment and 7 subjects (43%) in the control groups had gained marked improvement. These results are statistically highly significant, (P = 0.01) at the end of the follow-up assessment.

CONCLUSIONS

A conclusion could be drawn that a single intense TENS treatment is an effective treatment for neck pain due to musculoskeletal disorders. On the other hand, TENS showed an effective pain relief with subjects who have a mild neck pain rather than those with severe symptoms.

KEYWORDS

Musculoskeletal disorders; Transcutaneous electrical nerve stimulation; Neck pain.

Ação da TENS acupuntural em acupontos na dor induzida pela hipotermia local (0-2º C)

INTRODUÇÃO: A dor é um fenômeno multidimensional que dificulta o desenvolvimento das atividades cotidianas. A aplicação de estimulação elétrica nervosa transcutânea (transcutaneous electrical nerve stimulation - TENS) está entre uma das modalidades mais usadas para o tratamento da dor. OBJETIVO: O objetivo deste estudo foi verificar se a TENS acupuntural (baixa frequência) influencia a dor aguda produzida pela hipotermia local em indivíduos saudáveis, quando os eletrodos estão localizados nos acupontos TA5 e CS6 e na aplicação placebo. MÉTODOS: Trinta e dois voluntários, de ambos os gêneros, foram alocados, aleatoriamente, nos grupos TENS e placebo. O estudo consistiu em três momentos: hipotermia sem eletroanalgesia, hipotermia com eletroanalgesia ou placebo, e hipotermia pós-eletroanalgesia ou placebo, para avaliar o efeito da TENS e do placebo na latência do limiar de dor e na intensidade da dor. RESULTADOS: Os resultados mostraram que a latência do limiar de dor aumenta significativamente quando comparados os momentos antes e depois do uso da TENS, enquanto o grupo placebo não mostrou significância entre seus ciclos de experimentação. A intensidade da dor não sofreu influencia da TENS e do placebo. CONCLUSÃO: Nossos resultados sugerem que a TENS acupuntural aplicada sobre a área dos acupontos TA5 e CS6 é eficaz em aumentar a latência do limiar de dor, mas não interfere na intensidade da dor.

Transcutaneous electrical nerve stimulation at both high and low frequencies activates ventrolateral periaqueductal grey to decrease mechanical hyperalgesia in arthritic rats

Transcutaneous electric nerve stimulation (TENS) is widely used for the treatment of pain. TENS produces an opioid-mediated antinociception that utilizes the rostroventromedial medulla (RVM). Similarly, antinociception evoked from the periaqueductal grey (PAG) is opioid-mediated and includes a relay in the RVM. Therefore, we investigated whether the ventrolateral or dorsolateral PAG mediates antinociception produced by TENS in rats. Paw and knee joint mechanical withdrawal thresholds were assessed before and after knee joint inflammation (3% kaolin/carrageenan), and after TENS stimulation (active or sham). Cobalt chloride (CoCl(2); 5 mM) or vehicle was microinjected into the ventrolateral periaqueductal grey (vlPAG) or dorsolateral periaqueductal grey (dlPAG) prior to treatment with TENS. Either high (100 Hz) or low (4 Hz) frequency TENS was then applied to the inflamed knee for 20 min. Active TENS significantly increased withdrawal thresholds of the paw and knee joint in the group microinjected with vehicle when compared to thresholds prior to TENS (P<0.001) or to sham TENS (P<0.001). The increases in withdrawal thresholds normally observed after TENS were prevented by microinjection of CoCl(2) into the vlPAG, but not the dlPAG prior to TENS and were significantly lower than controls treated with TENS (P<0.001). In a separate group of animals, microinjection of CoCl(2) into the vlPAG temporarily reversed the decreased mechanical withdrawal threshold suggesting a role for the vlPAG in the facilitation of joint pain. No significant difference was observed for dlPAG. We hypothesize that the effects of TENS are mediated through the vlPAG that sends projections through the RVM to the spinal cord to produce an opioid-mediated analgesia.

Transcutaneous Electrical Nerve Stimulation (TENS) A Possible Aid for Pain Relief in Developing Countries?

Transcutaneous electrical nerve stimulation (TENS) refers to the delivery of electrical currents through the skin to activate peripheral nerves. The technique is widely used in developed countries to relieve a wide range of acute and chronic pain conditions, including pain resulting from cancer and its treatment. There are many systematic reviews on TENS although evidence is often inconclusive because of shortcomings in randomised control trials methodology. In this overview the basic science behind TENS will be discussed, the evidence of its effectiveness in specific clinical conditions analysed and a case for its use in pain management in developing countries will be made.

Effectiveness of transcutaneous electrical nerve stimulation for treatment of hyperalgesia and pain

Transcutaneous electrical nerve stimulation (TENS) is a nonpharmacologic treatment for pain relief. TENS has been used to treat a variety of painful conditions. This review updates the basic and clinical science regarding the use of TENS that has been published in the past 3 years (ie, 2005-2008). Basic science studies using animal models of inflammation show changes in the peripheral nervous system, as well as in the spinal cord and descending inhibitory pathways, in response to TENS. Translational studies show mechanisms to prevent analgesic tolerance to repeated application of TENS. This review also highlights data from recent randomized, placebo-controlled trials and current systematic reviews. Clinical trials suggest that adequate dosing, particularly intensity, is critical to obtaining pain relief with TENS. Thus, evidence continues to emerge from both basic science and clinical trials supporting the use of TENS for the treatment of a variety of painful conditions while identifying strategies to increase TENS effectiveness.