Evaluation of TENS during screening flexible sigmoidoscopy. Feasibility study of Transcutaneous Electrical Nerve Stimulation (TENS) for cancer bone pain. TENS for children's procedural pain. A randomized controlled study on the effect of two different treatments (FREMS AND TENS) in myofascial pain syndrome. An evaluation of transcutaneous electrical nerve stimulation for pain relief in labour. Randomization is important in studies with pain outcomes: systematic review of transcutaneous electrical nerve stimulation in acute postoperative pain. A controlled trial of transcutaneous electrical nerve stimulation (TENS) and exercise for chronic low back pain. Use of transcutaneous electrical nerve stimulation for postoperative pain. Pain reducing effect of three types of transcutaneous electrical nerve stimulation in patients with chronic pain: a randomized crossover trial. Results of a randomized controlled trial to examine the efficacy of a chronic pain self-management group for older adults [ISRCTN11899548]. Outcome of transcutaneous electrical nerve stimulation in chronic pain: short-term results of a double-blind, randomised, placebo-controlled trial. Transcutaneous nerve stimulation (TENS) during the first stage of labour: a randomized clinical trial. Transcranial DC stimulation coupled with TENS for the treatment of chronic pain: a preliminary study. Repetitive magnetic stimulation: a novel therapeutic approach for myofascial pain syndrome. Efficacy of transcutaneous electrical nerve stimulation (tens) for chronic low-back pain in a multiple sclerosis population: a randomized, placebo-controlled clinical trial. Randomised controlled trial comparing the effectiveness of electroacupuncture and TENS for low back pain: a preliminary study for a pragmatic trial. A comparison of high- versus low-intensity, high-frequency transcutaneous electric nerve stimulation for painful postpartum uterine contractions. Pain relief in labour using transcutaneous electrical nerve stimulation (TENS). A TENS/TENS placebo controlled study in two parity groups. Combined neuromuscular electrical stimulation and transcutaneous electrical nerve stimulation for treatment of chronic back pain: a double-blind, repeated measures comparison. Chronic pain self-management for older adults: a randomized controlled trial [ISRCTN11899548].
The expectation of pain is a statistically significant factor negatively affecting patient compliance with current screening flexible sigmoidoscopy recommendations. Numerous pain reduction modalities have been studied with limited success. Transcutaneous electrical nerve stimulation (TENS) has been used to treat pain of various origins. The purpose of this pilot study was to determine the efficacy of TENS in reducing discomfort experienced during screening flexible sigmoidoscopy.A double-blind study was conducted in which 90 subjects were randomized to receive TENS, sham TENS, or control (standard care). The same pulse frequency and intensity were used for all subjects in the TENS group. Subjects completed preprocedural and postprocedural questionnaires, and the endoscopist completed a postprocedural questionnaire. A slight, but statistically insignificant (p =.526) reduction in the mean pain score reported by the TENS group was noted when compared with the sham TENS and control groups (2.00, 2.27, and 2.23 respectively). In light of the fact that only one pulse frequency and intensity of the TENS intervention were used in this study, further study with this safe and cost-effective modality is warranted. This multicenter study assessed the feasibility of conducting a phase III trial of transcutaneous electrical nerve stimulation (TENS) in patients with cancer bone pain recruited from palliative care services. Eligible patients received active and placebo TENS for 1 hour at site of pain in a randomized crossover design; median interval between applications 3 days. Responses assessed at 30 and 60 minutes included numerical and verbal ratings of pain at rest and on movement, and pain relief. Recruitment, tolerability, adverse events, and effectiveness of blinding were also evaluated. Twenty-four patients were randomised and 19 completed both applications. The intervention was well tolerated. Five patients withdrew: 3 due to deteriorating performance status, and 2 due to increased pain (1 each following active and placebo TENS). Confidence interval estimation around the differences in outcomes between active and placebo TENS suggests that TENS has the potential to decrease pain on movement more than pain on rest. Nine patients did not consider that a placebo was used; the remaining 10 correctly identified placebo TENS. Feasibility studies are important in palliative care prior to undertaking clinical trials. Our findings suggest that further work is required on recruitment strategies and refining the control arm before evaluating TENS in cancer bone pain.
                Cancer bone pain is common and severe, and partly mediated by hyperexcitability. Animal studies suggest that Transcutaneous Electrical Nerve Stimulation can reduce hyperalgesia. This study examined the feasibility of evaluating TENS in patients with cancer bone pain in order to optimize methods before a phase III trial.
                Copyright 2010 American Pain Society. Published by Elsevier Inc. All rights reserved. A 3 x 6 factorial design with a double blind and placebo control was employed to investigate the effect of TENS treatment on pain produced by venipuncture. The three treatment groups consisted of TENS, placebo-TENS and control. Subjects were blocked into six 2-year age groups (ages: 5-17 years). During the period of the study, 896 children attending the outpatient laboratory of a general hospital were screened and 514 children completed the study. The data which were collected before venipuncture included expected pain and state anxiety. Following venipuncture, pain intensity was measured with a vertical visual analogue scale (VAS) and pain affect was assessed with McGrath's faces scale. Significant main effects for treatment and age groups were obtained. Pain intensity and affect were lowest for the TENS group and highest for the control group. The pain scores were greatest for lower age groups and lowest for higher age groups. The results of this study support the use of TENS for children's pain and the need for interventions for children's procedural pain. Myofascial pain syndrome (MPS) is a frequent cause of chronic muscoloskeletal pain. Transcutaneous electrical nerve stimulation (TENS) is one of the most frequently employed treatments in MPS. The aim of this study is to compare the short and medium-term effects of frequency modulated neural stimulation (FREMS) to those of TENS in MPS.
                Forty subjects with upper trapezius MPS were randomly allocated to 1 of 2 groups, treated with either FREMS (n=19) or TENS (n=21). Each treatment consisted in 10 sessions lasting 20 min each. Patients were evaluated before treatment, at 1 week, and at 1 and 3 months after the end of treatment. Clinical evaluation included parameters for measurement of pain levels using the neck pain and disability visual analogue scale (NPDVAS) and algometry, evaluation of myofascial trigger point characteristics and measurement of the range of cervical movement (range of motion, ROM).
                The FREMS group showed a significant improvement in the NPDVAS, algometry, in myofascial trigger point characteristics, and in the ROM (homolateral rotation, controlateral rotation, bending and extension) after the end of treatment and at 1 and 3 months follow-up evaluation. The TENS group showed significant improvement in the same outcome measures except for algometry and cervical extension, but these improvements were maintained only at the 1 month follow-up evaluation. However, were not observed statistically significant differences between FREMS of TENS in many of outcome measures.
                Both FREMS and TENS have positive short-term effects on MPS. But, medium-term effects were achieved only with FREMS. The effectiveness of transcutaneous nerve stimulation (TENS) for pain relief in labour was evaluated by randomizing 280 patients in early labour into 2 groups. Inoperative sham machines were applied to patients in the control group and active units to those in the test group. Neither patients nor attending labour ward staff were aware of which group the patient was in. The intensity of low back pain and abdominal pain was assessed by the patient each hour on a visual analogue pain scale. Each patient served as her own control by switching off the machine for 2 contractions every hour and then recording the intensity of pain. The amount of conventional analgesia each patient received was recorded by labour ward staff. There was no difference in the intensity of pain recorded by each group. Nor was there any difference between the 2 groups in the change of pain experienced when the machine was switched off. Moreover there was no difference in the amount of other analgesia required. Some differences were found when those with little low back pain were excluded from the study. We conclude that TENS is ineffective as a routine method of pain relief in labour. It is likely to benefit only those with severe back pain and then only to a modest degree. We set out to examine the evidence for the importance of randomization of transcutaneous electrical nerve stimulation (TENS) in acute postoperative pain. Controlled studies were sought; randomization and analgesic and adverse effect outcomes were summarized. Forty-six reports were identified by searching strategies. Seventeen reports with 786 patients could be regarded unequivocally as randomized controlled trials (RCT) in acute postoperative pain. No meta-analysis was possible. In 15 of 17 RCT, we judged there to be no benefit of TENS compared with placebo. Of the 29 excluded trials, 19 had pain outcomes but were not RCT; in 17 of these 19 TENS studies, the authors concluded that TENS had a positive analgesic effect. No adverse effects were reported. Non-randomized studies overestimated treatment effects. A number of treatments are widely prescribed for chronic back pain, but few have been rigorously evaluated. We examined the effectiveness of transcutaneous electrical nerve stimulation (TENS), a program of stretching exercises, or a combination of both for low back pain. Patients with chronic low back pain (median duration, 4.1 years) were randomly assigned to receive daily treatment with TENS (n = 36), sham TENS (n = 36), TENS plus a program of exercises (n = 37), or sham TENS plus exercises (n = 36). After one month no clinically or statistically significant treatment effect of TENS was found on any of 11 indicators of outcome measuring pain, function, and back flexion; there was no interactive effect of TENS with exercise. Overall improvement in pain indicators was 47 percent with TENS and 42 percent with sham TENS (P not significant). The 95 percent confidence intervals for group differences excluded a major clinical benefit of TENS for most outcomes. By contrast, after one month patients in the exercise groups had significant improvement in self-rated pain scores, reduction in the frequency of pain, and greater levels of activity as compared with patients in the groups that did not exercise. The mean reported improvement in pain scores was 52 percent in the exercise groups and 37 percent in the nonexercise groups (P = 0.02). Two months after the active intervention, however, most patients had discontinued the exercises, and the initial improvements were gone. We conclude that for patients with chronic low back pain, treatment with TENS is no more effective than treatment with a placebo, and TENS adds no apparent benefit to that of exercise alone. This study examined the effects of transcutaneous electrical nerve stimulation (TENS) on incisional pain caused by the procedure of cleaning and packing an abdominal surgical wound. Seventy-five subjects (mean age 56.9 years) were randomly assigned to one of three intervention groups: TENS, placebo-TENS, or no-treatment control. The appropriate experimental treatment was administered during the routine dressing change which took place two mornings after surgery. Using an 11-point, visual analogue pain scale, subjects described pain experienced during the dressing change. Subjects who received TENS reported a significantly lower level of pain after dressing change than did those subjects who received either placebo-TENS or no-treatment. Drug administration variables did not contribute significantly to level of reported pain. Transcutaneous electrical nerve stimulation (TENS) is a frequently applied therapy in chronic pain although evidence for effectiveness is inconclusive. Several types of TENS, based on different combinations of frequency, pulse duration and intensity, exist. The precise mechanism of action and the relevance of combinations of stimulus parameters are still unclear. To compare the effectiveness of three types of TENS we conducted a randomized, single blinded crossover trial. Patients received two times a 2-week period of daily TENS treatment, separated by a washout period of 2 weeks. In total, 180 chronic pain patients were randomized into three groups. In group 1, high frequency, low intensity TENS (HFT) was compared with high frequency, high intensity TENS (HIT). In groups 2 and 3, HFT and HIT were compared with a control TENS (COT). The order of applying the different modalities of TENS in each group was also randomized. Primary outcome was the patient's overall assessment of effectiveness and pain reduction (VAS). No differences were found in patient's assessment or pain reducing effect between the three groups, indicating no superiority of one type of TENS. In total, 56% continued TENS after the 2-week treatment period. At 6 months, 42% of all patients still used TENS. We concluded that there were no differences in effectiveness for the three types of TENS used in this study. Because no placebo group was included, no definite conclusions on effectiveness of TENS in general in the treatment of chronic pain could be made. Chronic pain is a common, disabling problem in older adults. Pain self-management training is a multimodal therapy that has been found to be effective in young to middle-aged adult samples; however, few studies have examined the effectiveness of this therapy in older adults. In this randomized, controlled trial, we evaluated a pain self-management training group (SMG) intervention as compared with an education-only (BOOK) control condition. Participants, 65 years of age or older who experienced persistent, noncancer pain that limited their activities, were recruited from 43 retirement communities in the Pacific Northwest of the United States. The primary outcome was physical disability, as measured by the Roland-Morris Disability Questionnaire. Secondary outcomes were depression (Geriatric Depression Scale), pain intensity (Brief Pain Inventory), and pain-related interference with activities (Brief Pain Inventory). Randomization occurred by facility to minimize cross-contamination between groups. Two-hundred and fifty-six individuals, mean age=81.8 (SD: 6.5), enrolled and 218 completed the study. No significant differences in outcomes were found between groups at post-intervention, 6-month follow-up, or 12-month follow-up. The SMG group showed a significantly greater increase over time, relative to the BOOK group, in two process measures, as measured by the Chronic Pain Coping Inventory: use of relaxation and use of exercise/stretching. In both cases, the increase was greatest from baseline to the post-intervention assessment. Study findings indicate that additional research is needed to determine the most effective content and delivery methods for self-management therapies targeted at older adults with chronic pain. The aim of this study was to test the efficacy of shortterm transcutaneous electrical nerve stimulation (TENS) treatment in chronic pain with respect to pain intensity and patients' satisfaction with treatment results. We therefore performed a randomised controlled trial comparing TENS and sham TENS. Patients, researchers and therapists were blinded for treatment allocation. One hundred and sixty-three patients with chronic pain referred to the Pain Centre entered the study. Conventional TENS and sham TENS were applied in the segments of pain, for a period of ten days. Outcome measures were pain intensity (visual analogue scale) and patients' satisfaction with treatment result (yes or no). The proportions of patients satisfied with treatment result differed significantly for TENS compared to sham TENS (58 and 42.7% respectively, chi(2)=3.8, p=0.05). However, no differences in pain intensity were found for patients treated with TENS or sham TENS. Only for patients satisfied with treatment results pain intensity gradually decrease equally both for TENS and sham TENS with repeated treatment application. Our objective was to study the efficacy of transcutaneous electrical nerve stimulation (TENS) in reducing pain during the first stage of labour. Using a prospective randomized placebo-controlled, double blind clinical trial, a patient-controlled analgesia system was used to measure differences in outcome. Trials took place in a labour unit at the St. Antonius Hospital, Nieuwegein, The Netherlands, during a period of 18 months. Forty-six patients, during the first stage of labour, were treated with TENS, and 48 with a placebo apparatus. Main outcome measures were pain relief, amount of administered analgesics, obstetrical and neonatal outcome, and side effects. No significant differences occurred between groups in the number of requests for pethidine/promethazine. The foetal outcome in both groups was the same. TENS and placebo were considered equally effective by both patients and staff. In conclusion, TENS was not more effective than a placebo apparatus in relieving pain during the first stage of labour. No adverse side-effects occurred. Based on evidence showing that electrical stimulation of the nervous system is an effective method to decrease chronic neurogenic pain, we aimed to investigate whether the combination of 2 methods of electrical stimulation-a method of peripheral stimulation [transcutaneous electrical nerve stimulation (TENS)] and a method of noninvasive brain stimulation [transcranial direct current stimulation (tDCS)]-induces greater pain reduction as compared with tDCS alone and sham stimulation.
                We performed a preliminary, randomized, sham-controlled, crossover, clinical study in which 8 patients were randomized to receive active tDCS/active TENS ("tDCS/TENS" group), active tDCS/sham TENS ("tDCS" group), and sham tDCS/sham TENS ("sham" group) stimulation. Assessments were performed immediately before and after each condition by a blinded rater.
                The results showed that there was a significant difference in pain reduction across the conditions of stimulation (P=0.006). Post hoc tests showed significant pain reduction as compared with baseline after the tDCS/TENS condition [reduction by 36.5% (+/-10.7), P=0.004] and the tDCS condition [reduction by 15.5% (+/-4.9), P=0.014], but not after sham stimulation (P=0.35). In addition, tDCS/TENS induced greater pain reduction than tDCS (P=0.02).
                The results of this pilot study suggest that the combination of TENS with tDCS has a superior effect compared with tDCS alone. The aim of this study was to evaluate the short, medium and long-term effects of peripheral repetitive magnetic stimulation (rMS) on myofascial pain compared with transcutaneous electrical nerve stimulation (TENS).Fifty-three subjects with myofascial trigger points (TPs) at the level of the superior trapezius muscle were allocated randomly to three groups. The first group (n=17) was treated with rMS, the second (n=18) with TENS and the third (n=18) received a placebo treatment. Each treatment consisted of ten daily 20-minute sessions. Patients were evaluated before and immediately following treatment, and at one and three months after the end of treatment. Outcome measures were: the "neck pain and disability visual analogue scale" (NPDVAS), an algometric evaluation of pain, an evaluation of the TP characteristics, and the range of cervical bending and rotation contralateral to the affected trapezius muscle. At the end of treatment, the rMS group showed a significant improvement in the NPDVAS, algometry, TP characteristics, and cervical contralateral rotation. This improvement also persisted at one and three months post-therapy. After treatment, the TENS group showed significant improvement in the same outcome measures except for algometry. At the one month follow-up visit, this improvement had returned to non significant levels in all outcome measures with the exception of NPDVAS. No significant effect of TENS was seen at the three-month follow-up visit. The placebo group showed no significant improvement in any measure. Our results strongly suggest that at medium and longer term intervals peripheral rMS may be more effective than TENS for the treatment of myofascial pain. This study was designed to investigate the hypoalgesic effects of self-applied transcutaneous electrical nerve stimulation (TENS) on chronic low-back pain (LBP) in a multiple sclerosis (MS) population.
                Ninety participants with probable or definite MS (aged 21 to 78 y) presenting with chronic LBP were recruited and randomized into 3 groups (n=30 per group): (1) low-frequency TENS group (4 Hz, 200 micros); (2) high-frequency TENS group (110 Hz, 200 micros); and (3) placebo TENS. Participants self-applied TENS for 45 minutes, a minimum of twice daily, for 6 weeks. Outcome measures were recorded at weeks 1, 6, 10, and 32. Primary outcome measures included: Visual Analog Scale for average LBP and the McGill Pain Questionnaire. Secondary outcome measures included: Visual Analog Scale for worst and weekly LBP, back and leg spasm; Roland Morris Disability Questionnaire; Barthel Index; Rivermead Mobility Index; Multiple Sclerosis Quality of Life-54 Instrument, and a daily logbook. Data were analyzed blind using parametric and nonparametric tests, as appropriate.
                Results indicated a statistically significant interactive effect between groups for average LBP (P=0.008); 1-way analysis of covariance did not show any significant effects at any time point once a Bonferonni correction was applied (P>0.05). However, clinically important differences were observed in some of the outcome measures in both active treatment groups during the treatment and follow-up periods.
                Although not statistically significant, the observed effects may have implications for the clinical prescription and the use of TENS within this population. The objective of this study was to compare the effectiveness of electroacupuncture and TENS for low back pain when the electroacupuncture is applied in a clinically realistic manner. The study was designed as an evaluator-blinded randomised controlled trial (RCT). The study was performed at the Tsukuba College of Technology Clinic in Japan. Twenty subjects, who suffered from low back pain (LBP) without sciatica, were recruited, using leaflets in Tsukuba city. Subjects were allocated to either an electroacupuncture (EA) group (10 patients) or a transcutaneous electrical nerve stimulation (TENS) group (10 patients). The procedure for EA was in accordance with standard practice at our clinic. The main outcome measures were a pain relief scale (100 mm visual analogue scale: VAS) and a LBP score recommended by the Japanese Orthopaedic Association (JOA Score). Mean VAS value during the 2-weeks experimental period of the EA group was significantly smaller than that of the TENS group (65 mm vs 86 mm; 95% CI, 4.126 - 37.953). JOA Score in the EA group improved significantly while that in the TENS group showed no change. Although some placebo effect may be included, EA appeared more useful than TENS in the short-term effect on low back pain. We suggest that more realistic acupuncture interventions based on standard practice should be employed in pragmatic RCTs. Breast-feeding in the postpartum period is known to induce intense uterine contractions with pain in the lower abdomen.
                The primary aim of this study was to compare the effects of high and low intensity, high frequency Transcutaneous Electric Nerve Stimulation (TENS) on pain and discomfort of postpartum uterine contractions. The secondary aim was to evaluate discomfort experienced from the stimulation itself.
                Twenty-one newly delivered women participated in this single-blind trial, 12 women received high intensity, high-frequency TENS (HI TENS) and 9 women received low intensity, high-frequency TENS (LI TENS). The electrodes were placed abdominally on each side of the uterus. Stimulation was done during one minute. Visual analogue scales were used to evaluate the intensity of the pain before and after stimulation. A verbal scale was used to estimate sensation of discomfort before, during and after stimulation.
                The median decrease in pain ratings before and after treatment by VAS was larger in the HI TENS group -49 mm (95% CI -66.5--33.2) than in the LI TENS group -21 mm (95% CI -39.0--20.0). The reduction of pain was most pronounced in the HI TENS group (median difference 28 (95% CI was 14.0-53.0). Furthermore, the HI TENS group experienced significantly less discomfort of the uterine contractions after stimulation (p<0.01) but they also experienced more discomfort of the stimulation than women in the LI TENS group (p<0.01).
                The women treated with HI TENS, experienced significantly less postpartum pain and discomfort to those treated with LI TENS even though the discomfort from the stimulation with HI TENS was greater. The analgesic effects of transcutaneous electrical nerve stimulation (TENS) in labour and effects on outcome were investigated in a double-blind TENS/TENS placebo controlled trial in 100 primigravidae and 50 women in their third labour. There were no differences between the TENS and the TENS placebo users in terms of pain concept or relief, and only 12 and 13% of primigravidae and 48 and 39% of the para 2 women completed labour without requiring other analgesia in their respective groups. The primigravidae who used either TENS or TENS placebo alone had shorter labours than those who required further analgesia. Although the outcome of labour for mother and infant were similar in the two groups, there was a higher operative delivery rate in women who also had epidural analgesia. There were highly significant differences between the TENS and the TENS placebo users in terms of favourable and unfavourable comments by the mothers and the midwives at 1 and 24 h after delivery. The evident consumer satisfaction for TENS suggests TENS has a part to play in analgesia in labour but the equivocal findings in terms of factors associated with pain relief points to the need for apparatus more specifically designed to cope with the special characteristics of the pain of labour. A preliminary examination of NMES and combined NMES/TENS for the management of chronic back pain.
                Double-blind, placebo-controlled, randomized repeated measures.
                Consecutive sample of 24 chronic back pain patients (16 women and 8 men) attending an outpatient pain clinic (mean age 51.67 years, mean pain duration 3.83 years). All treatments were administered at home.
                Subjects self-administered NMES, combined NMES/TENS, TENS, and placebo treatments. Each treatment had a duration of 5 consecutive hours per day over 2 consecutive days, with a 2-day hiatus between treatments to minimize carryover effects.
                Pain reduction was assessed through pretreatment to posttreatment differences on the Present Pain Intensity (PPI) scale, and a visual analogue scale of Pain Intensity (VAS-I). Posttreatment pain relief was assessed using a visual analogue scale of Pain Relief (VAS-R).
                Combined treatment, NMES, and TENS each produced significant pretreatment to posttreatment reductions in pain intensity as measured by both the PPI and VAS-I (p < .05). Combined treatment was superior to placebo on pain reduction (p = .001, p = .016) as well as pain relief (p < .001). Combined treatment was also superior to both TENS and NMES for pain reduction and pain relief (p < .01). NMES and TENS were superior only to placebo for pain relief (p < .001).
                Combined NMES/TENS treatment consistently produced greater pain reduction and pain relief than placebo, TENS, or NMES. NMES alone, although less effective, did produce as much pain relief as TENS. Although preliminary, this pattern of results suggests that combined NMES/TENS may be a valuable adjunct in the management of chronic back pain. Further research investigating the effectiveness of both NMES and combined NMES/TENS seems warranted. Chronic pain is a common and frequently disabling problem in older adults. Clinical guidelines emphasize the need to use multimodal therapies to manage persistent pain in this population. Pain self-management training is a multimodal therapy that has been found to be effective in young to middle-aged adult samples. This training includes education about pain as well as instruction and practice in several management techniques, including relaxation, physical exercise, modification of negative thoughts, and goal setting. Few studies have examined the effectiveness of this therapy in older adult samples.
                This is a randomized, controlled trial to assess the effectiveness of a pain self-management training group intervention, as compared with an education-only control condition. Participants are recruited from retirement communities in the Pacific Northwest of the United States and must be 65 years or older and experience persistent, noncancer pain that limits their activities. The primary outcome is physical disability, as measured by the Roland-Morris Disability Questionnaire. Secondary outcomes are depression (Geriatric Depression Scale), pain intensity (Brief Pain Inventory), and pain-related interference with activities (Brief Pain Inventory). Randomization occurs by facility to minimize cross-contamination between groups. The target sample size is 273 enrolled, which assuming a 20% attrition rate at 12 months, will provide us with 84% power to detect a moderate effect size of.50 for the primary outcome.
                Few studies have investigated the effects of multimodal pain self-management training among older adults. This randomized controlled trial is designed to assess the efficacy of a pain self-management program that incorporates physical and psychosocial pain coping skills among adults in the mid-old to old-old range.
Since the last version of this review, new relevant studies have not provided additional information to change the conclusions. Published literature on the subject lacks the methodological rigour or robust reporting needed to make confident assessments of the role of TENS in chronic pain management. Large multi-centre RCTs of TENS in chronic pain are still needed.