D. Dailey

Transcutaneous electrical nerve stimulation reduces pain, fatigue and hyperalgesia while restoring central inhibition in primary fibromyalgia

Summary Pain and fatigue during movement, but not at rest, are reduced by a onetime 30‐m treatment with active transcutaneous electrical nerve stimulation (TENS) in individuals with fibromyalgia. Abstract Because transcutaneous electrical nerve stimulation (TENS) works by reducing central excitability and activating central inhibition pathways, we tested the hypothesis that TENS would reduce pain and fatigue and improve function and hyperalgesia in people with fibromyalgia who have enhanced central excitability and reduced inhibition. The current study used a double‐blinded randomized, placebo‐controlled cross‐over design to test the effects of a single treatment of TENS with people with fibromyalgia. Three treatments were assessed in random order: active TENS, placebo TENS and no TENS. The following measures were assessed before and after each TENS treatment: pain and fatigue at rest and in movement; pressure pain thresholds, 6‐m walk test, range of motion; 5‐time sit‐to‐stand test, and single‐leg stance. Conditioned pain modulation was completed at the end of testing. There was a significant decrease in pain and fatigue with movement for active TENS compared to placebo and no TENS. Pressure pain thresholds increased at the site of TENS (spine) and outside the site of TENS (leg) when compared to placebo TENS or no TENS. During active TENS, conditioned pain modulation was significantly stronger compared to placebo TENS and no TENS. No changes in functional tasks were observed with TENS. Thus, the current study suggests TENS has short‐term efficacy in relieving symptoms of fibromyalgia while the stimulator is active. Future clinical trials should examine the effects of repeated daily delivery of TENS, similar to the way in which TENS is used clinically on pain, fatigue, function, and quality of life in individuals with fibromyalgia.

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.

Do Cognitive and Physical Fatigue Tasks Enhance Pain, Cognitive Fatigue, and Physical Fatigue in People With Fibromyalgia?

Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task, and a dual fatigue task.

Effect of Transcutaneous Electrical Nerve Stimulation on Pain, Function, and Quality of Life in Fibromyalgia: A Double-Blind Randomized Clinical Trial

Background Fibromyalgia is a common chronic pain condition that has a significant impact on quality of life and often leads to disability. To date, there have been few well-controlled trials assessing the utility of nonpharmacological treatment modalities such as transcutaneous electrical nerve stimulation (TENS) in the management of pain and improvement in function in individuals with fibromyalgia. Objectives The purpose of this study will be to complete a long-term, multicenter study to assess the effects of TENS in women with fibromyalgia. Design This will be a phase II randomized, double-blind, placebo-controlled, multicenter clinical trial. Participants Three hundred forty-three participants with fibromyalgia will be recruited for this study. Intervention Participants will be randomly assigned to 1 of 3 groups: the intervention (TENS), placebo, or no treatment. After completing the randomized period, all participants will receive the intervention for 1 month. The participants will be asked to use TENS at the highest tolerable level for at least 2 hours daily during physical activity. Measurements The primary outcome will be pain with movement, with secondary outcomes assessing functional abilities, patient-reported outcomes, and quantitative sensory testing. Limitations Because having participants refrain from their typical medications is not practical, their usage and any change in medication use will be recorded. Conclusions The results of this study will provide some of the first evidence from a large-scale, double-blind, placebo-controlled trial on the effectiveness of TENS on pain control and quality-of-life changes in patients with fibromyalgia.

Reliability and Construct Validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) Instruments in Women with Fibromyalgia.

ObjectivenThe Patient-Reported Outcomes Measurement Information System (PROMIS) was developed to standardize measurement of clinically relevant patient-reported outcomes. This study evaluated the reliability and construct validity of select PROMIS static short-form (SF) instruments in women with fibromyalgia.nnnDesignnAnalysis of baseline data from the Fibromyalgia Activity Study with TENS (FAST), a randomized controlled trial of the efficacy of transcutaneous electrical nerve stimulation.nnnSettingnDual site, university-based outpatient clinics.nnnSubjectsnWomen aged 20 to 67 years diagnosed with fibromyalgia.nnnMethodsnParticipants completed the Revised Fibromyalgia Impact Questionnaire (FIQR) and 10 PROMIS static SF instruments. Internal consistency was calculated using Cronbach alpha. Convergent validity was examined against the FIQR using Pearson correlation and multiple regression analysis.nnnResultsnPROMIS static SF instruments had fair to high internal consistency (Cronbach αu2009=u20090.58 to 0.94, P u2009<u20090.05). PROMIS physical function domain score was highly correlated with FIQR function score (ru2009=u2009-0.73). The PROMIS total score was highly correlated with the FIQR total score (ru2009=u2009-0.72). Correlations with FIQR total score of each of the three PROMIS domain scores were ru2009=u2009-0.65 for physical function, ru2009=u2009-0.63 for global, and ru2009=u2009-0.57 for symptom domain. PROMIS physical function, global, and symptom scores explained 58% of the FIQR total score variance.nnnConclusionsnSelect PROMIS static SF instruments demonstrate convergent validity with the FIQR, a legacy measure of fibromyalgia disease severity. These results highlight the potential utility of select PROMIS static SFs for assessment and tracking of patient-reported outcomes in fibromyalgia.

Meta-analysis of transcutaneous electrical nerve stimulation for relief of spinal pain

We conducted a systematic review and meta‐analysis analysing the existing data on transcutaneous electrical nerve stimulation (TENS) or interferential current (IFC) for chronic low back pain (CLBP) and/or neck pain (CNP) taking into account intensity and timing of stimulation, examining pain, function and disability. Seven electronic databases were searched for TENS or IFC treatment in non‐specific CLBP or CNP. Four reviewers independently selected randomized controlled trials (RCTs) of TENS or IFC intervention in adult individuals with non‐specific CLBP or CNP. Primary outcomes were for self‐reported pain intensity and back‐specific disability. Two reviewers performed quality assessment, and two reviewers extracted data using a standardized form. Nine RCTs were selected (eight CLBP; one CNP), and seven studies with complete data sets were included for meta‐analysis (655 participants). For CLBP, meta‐analysis shows TENS/IFC intervention, independent of time of assessment, was significantly different from placebo/control (p < 0.02). TENS/IFC intervention was better than placebo/control, during therapy (p = 0.02), but not immediately after therapy (p = 0.08), or 1–3 months after therapy (p = 0.99). Analysis for adequate stimulation parameters was not significantly different, and there was no effect on disability. This systematic review provides inconclusive evidence of TENS benefits in low back pain patients because the quality of the studies was low, and adequate parameters and timing of assessment were not uniformly used or reported. Without additional high‐quality clinical trials using sufficient sample sizes and adequate parameters and outcome assessments, the outcomes of this review are likely to remain unchanged.

Perceived function and physical performance are associated with pain and fatigue in women with fibromyalgia

BackgroundFibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue and associated with significant impairment in perceived function and reduced physical performance. The purpose of this study was to determine the degree to which pain and fatigue are associated with perceived function and physical performance in women with fibromyalgia.MethodsHierarchical linear regression determined the contribution of pain and fatigue (Numeric Rating Scale (NRS) for resting, movement and combined) to perceived function (Fibromyalgia Impact Questionnaire Revised - Function Subscale, FIQR-Function), Multidimensional Assessment of Fatigue - Activities of Daily Living (MAF-ADL) and SF-36 Physical Function Subscale (SF-36-PF) and physical performance (6-Minute Walk Test, 6MWT and Five Time Sit To Stand, 5TSTS) while controlling for age, body mass index, pain catastrophizing, fear of movement, anxiety, and depression in women with fibromyalgia (Nu2009=u200994).ResultsFor perceived function, movement pain and movement fatigue together better predicted FIQR-function (adjusted R2u2009=u20090.42, pu2009≤u20090.001); MAF-ADL (adjusted R2u2009=u20090.41, pu2009≤u20090.001); and SF-36-PF function (adjusted R2u2009=u20090.34, pu2009≤u20090.001). For physical performance measures, movement pain and fatigue together predicted 6MWT distance (adjusted R2u2009=u20090.42, pu2009≤u20090.001) and movement fatigue alone predicted performance time on the 5TSTS (adjusted R2u2009=u20090.20, pu2009≤u20090.001).ConclusionsPain and fatigue are significantly associated with and explain more than one-third of the variance in perceived function and physical performance in women with fibromyalgia.Trial registrationNIH Clinicaltrials.gov Registration: NCT01888640. Registered 13 June 2013.

Skin impedance is not a factor in transcutaneous electrical nerve stimulation effectiveness

Objective Transcutaneous electrical nerve stimulation (TENS) is a nonpharmacological intervention used to manage pain using skin surface electrodes. Optimal electrode placement is unclear. We hypothesized that better analgesia would occur if electrodes were placed over sites with lower skin impedance. Optimal site selection (OSS) and sham site selection (SSS) electrode sites on the forearm were identified using a standard clinical technique. Methods Experiment 1 measured skin impedance in the forearm at OSS and SSS. Experiment 2 was a crossover design double-blind randomized controlled trial comparing OSS-TENS, SSS-TENS, and placebo TENS (P-TENS) to confirm differences in skin impedance between OSS and SSS, and measure change in pressure pain threshold (PPT) following a 30-minute TENS treatment. Healthy volunteers were recruited (ten for Experiment 1 [five male, five female] and 24 for Experiment 2 [12 male, 12 female]). TENS was applied for 30 minutes at 100 Hz frequency, 100 µs pulse duration, and “strong but nonpainful” amplitude. Results Experiment 1 results demonstrate significantly higher impedance at SSS (17.69±1.24 Ω) compared to OSS (13.53±0.57 Ω) (P=0.007). For Experiment 2, electrode site impedance was significantly higher over SSS, with both the impedance meter (P=0.001) and the TENS unit (P=0.012) compared to OSS. PPT change was significantly greater for both OSS-TENS (P=0.024) and SSS-TENS (P=0.025) when compared to P-TENS. PPT did not differ between the two active TENS treatments (P=0.81). Conclusion Skin impedance is lower at sites characterized as optimal using the described technique of electrode site selection. When TENS is applied at adequate intensities, skin impedance is not a factor in attainment of hypoalgesia of the forearm in healthy subjects. Further investigation should include testing in patients presenting with painful conditions.

Somatic symptom presentations in women with fibromyalgia are differentially associated with elevated depression and anxiety

This study examined whether depression and anxiety differentially relate to fatigue, sleep disturbance, pain catastrophizing, fear of movement, and pain severity in women with fibromyalgia. Baseline data from the Fibromyalgia Activity Study with Transcutaneous Electrical Nerve Stimulation were analyzed. Of 191 participants, 50u2009percent reported high anxiety and/or depression (17% high anxiety, 9% high depression, and 24% both). Fatigue and sleep impairment were associated with high depression (pu2009<u20090.05). Pain severity, pain catastrophizing, and fear of movement were associated with high anxiety and high depression (pu2009<u20090.05). Possible implications for underlying mechanisms and the need for targeted treatments are discussed.

Development of a method to maximize the transcutaneous electrical nerve stimulation intensity in women with fibromyalgia

Introduction Transcutaneous electrical nerve stimulation (TENS) is a non-pharmacological intervention clinically used for pain relief. The importance of utilizing the adequate stimulation intensity is well documented; however, clinical methods to achieve the highest possible intensity are not established. Objectives Our primary aim was to determine if exposure to the full range of clinical levels of stimulation, from sensory threshold to noxious, would result in higher final stimulation intensities. A secondary aim explored the association of pain, disease severity, and psychological variables with the ability to achieve higher final stimulation intensity. Methods Women with fibromyalgia (N=143) were recruited for a dual-site randomized controlled trial – Fibromyalgia Activity Study with TENS (FAST). TENS electrodes and stimulation were applied to the lumbar area, and intensity was increased to sensory threshold (ST), then to “strong but comfortable” (SC1), then to “noxious” (N). This was followed by a reduction to the final stimulation intensity of “strong but comfortable” (SC2). We called this the Setting of Intensity of TENS (SIT) test. Results There was a significant increase from SC1 (37.5 mA IQR: 35.6–39.0) to SC2 (39.2 mA IQR: 37.1–45.3) (p<0.0001) with a mean increase of 1.7 mA (95% CI: 1.5, 2.2). Linear regression analysis showed that those with the largest increase between SC1 and N had the largest increase in SC2–SC1. Further, those with older age and higher anxiety were able to achieve greater increases in intensity (SC2–SC1) using the SIT test. Conclusion The SC2–SC1 increase was significantly associated with age and anxiety, with greater mean increases associated with older age and higher anxiety. Thus, although all patients may benefit from this protocol, older women and women with elevated anxiety receive the greatest benefit.