Low-frequency Transcutaneous Electrical Nerve Stimulation Research Articles

Electrical stimulation for pain relief in knee osteoarthritis: systematic review and network meta-analysis

To investigate the efficacy of different electrical stimulation (ES) therapies in pain relief of patients with knee osteoarthritis (OA). Electronic databases including MEDLINE, Embase and Cochrane Library were searched through for randomized controlled trials (RCTs) comparing any ES therapies with control interventions (sham or blank) or with each other. Bayesian network meta-analysis was used to combine both the direct and indirect evidence on treatment effectiveness. 27 trials and six kinds of ES therapies, including high-frequency transcutaneous electrical nerve stimulation (h-TENS), low-frequency transcutaneous electrical nerve stimulation (l-TENS), neuromuscular electrical stimulation (NMES), interferential current (IFC), pulsed electrical stimulation (PES), and noninvasive interactive neurostimulation (NIN), were included. IFC is the only significantly effective treatment in terms of both pain intensity and change pain score at last follow-up time point when compared with the control group. Meanwhile, IFC showed the greatest probability of being the best option among the six treatment methods in pain relief. These estimates barely changed in sensitivity analysis. However, the evidence of heterogeneity and the limitation in sample size of some studies could be a potential threat to the validity of results. IFC seems to be the most promising pain relief treatment for the management of knee OA. However, evidence was limited due to the heterogeneity and small number of included trials. Although the recommendation level of the other ES therapies is either uncertain (h-TENS) or not appropriate (l-TENS, NMES, PES and NIN) for pain relief, it is likely that none of the interventions is dangerous. LevelⅡ, systematic review and network meta-analysis of RCTs.

Low- and high-frequency transcutaneous electrical nerve stimulation have no deleterious or teratogenic effects on pregnant mice

ObjectiveTo evaluate the effects of application of transcutaneous electrical nerve stimulation (TENS) at low and high frequencies to the abdomens of Swiss mice throughout pregnancy. DesignExperimental animal study. SettingResearch laboratory. ParticipantsThirty Swiss mice received TENS throughout pregnancy. They were divided into three groups (n=10): placebo, low-frequency TENS (LF group) and high-frequency TENS (HF group). InterventionsIn the placebo group, the electrodes were applied to the abdominal region without any electrical current. In the LF group, the frequency was 10Hz, pulse duration was 200μs and intensity started at 2mA. In the HF group, the same parameters were applied and the frequency was 150Hz. All stimulation protocols were applied for 20min/day from Day 0 until Day 20. Main outcome measuresThe pregnant mice were weighed on Days 0, 7, 14 and 20 to verify weekly weight gain by two-way analysis of variance. The numbers of fetuses, placentas, implantations, resorptions and major external fetal malformations on Day 20 were analysed using the Kruskal–Wallis test. ResultsNo significant differences were found between the placebo and TENS groups (P>0.05). ConclusionApplication of low- and high-frequency TENS to the abdomens of pregnant mice did not cause any deleterious or major teratogenic effects.

High and low frequency transcutaneous electrical nerve stimulation in post-cesarean pain intensity

The current study aim was evaluate the analgesic effect of TENS modulation for high (100 Hz) and low (4 Hz) frequency in post-cesarean pain. 34 postpartum women were randomly divided into three treatment groups: 100 Hz (G100), 4 Hz (G4) and Placebo (GP) (appliance off). Pain intensity was assessed by the NRS (Numeric Rating Scale) before, immediately after application of TENS, and every 20 minutes until an hour after the eletroanalgesia session. We used the Friedman test and Mann-Whitney U test (p<0.05) for statistical analysis. The results showed significant reduction of NRS in G100 only relative to pretreatment condition (p<0.05). At intervals after treatment, the G100 had a significant reduction of pain during all intervals (p<0.05). The G4 has significantly decreased only in intervals of 40' and 60', and the GP, only in the range of 60' (p<0.05). Modulation of TENS for high pulse rate showed greater analgesic effect than the low frequency TENS in post-cesarean mothers.

High-Frequency Transcutaneous Electrical Nerve Stimulation Alleviates Spasticity After Spinal Contusion by Inhibiting Activated Microglia in Rats

Background. Transcutaneous electrical nerve stimulation (TENS) can be used as a physical therapy for spasticity, but the effects of TENS on spasticity and its underlying mechanisms remain unclear. Objective. The purpose of this study was to test the effects of TENS on spasticity and the role of activated microglia as underlying mechanisms of TENS treatment for spasticity in rats with a 50-mm contusive spinal cord injury (SCI). Methods. A spinal contusion was made at the T12 spinal segment in adult male Sprague-Dawley rats using the NYU impactor. Behavioral tests for motor function were conducted before and after SCI and before and after TENS application. To assess spasticity, the modified Ashworth scale (MAS) was used before and after SCI, high-frequency (HF)/low-frequency (LF) TENS application at 3 different intensities (motor threshold [MT], 50% and 90% MT) or minocycline administration. Immunohistochemistry for microglia was performed at the lumbar spinal segments. Results. Motor recovery reached a plateau approximately 28 days after SCI. Spasticity was well developed and was sustained above the MAS grade of 3, beginning at 28 days after SCI. HF-TENS at 90% MT significantly alleviated spasticity. Motor function did not show any significant changes with LF- or HF-TENS treatment. HF-TENS significantly reduced the proportion of activated microglia observed after SCI. Minocycline, the microglia inhibitor, also significantly alleviated spasticity with the reduction of activated microglia expression. Conclusions. These results suggest that HF-TENS at 90% MT alleviates spasticity in rats with SCI by inhibiting activated microglia.

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.

Placebo-Induced Changes in Excitatory and Inhibitory Corticospinal Circuits during Motor Performance

Despite behavioral evidence showing placebo modulations of motor performance, the neurophysiological underpinnings of these effects are still unknown. By applying transcranial magnetic stimulation (TMS) over the primary motor cortex, we investigated whether a placebo modulation of force could change the excitability of the corticospinal system. Healthy human volunteers performed a motor task by pressing a piston as strongly as possible with the right index finger. Two experimental groups were instructed that treatment with peripheral low-frequency transcutaneous electrical nerve stimulation (TENS) applied on the first dorsal interosseus would induce force enhancement. One experimental group was conditioned about the effects of TENS with a surreptitious amplification of the visual feedback signaling the force level. The other group, instead, was only verbally influenced, without conditioning. At the end of the instructive placebo procedure, the two experimental groups reached higher levels of force, believed that TENS had been effective and expected to perform better compared with two control groups, who were not influenced about TENS. Moreover, the experimental groups presented enhanced excitability of the corticospinal system in the muscle specifically involved in the task (first dorsal interosseus), as shown by increased amplitude of the motor evoked potentials and decreased duration of the cortical silent period (the latter only in the conditioned group). Crucially, the TMS pulse was delivered when all the subjects exerted the same amount of force, ruling out bottom-up influences. These findings hint at a top-down, cognitive enhancement of corticospinal excitability as a neural signature of placebo modulation of motor performance.

The effects of ULF–TENS stimulation on gnathology: the state of the art

Aims: The aim of this study was to evaluate the state of the art in the current literature regarding the effect of ultra low frequency–transcutaneous electrical nerve stimulation (ULF–TENS) on patients with temporomandibular disorders (TMD).Methodology: The authors reviewed the literature through a thorough manual and electronic research on PubMed database (using the Medical Subject Headings thesaurus) and subsequent analysis of all the found papers regarding the effect of TENS on TMD patients. No randomized controlled trials on the investigated topic were found. Only eight papers regarding controlled clinical trials (CCT) were selected according to the search strategy selection criteria.Results: According to the available literature and the authors’ experience, ULF–TENS seems to be a valid support in the management of TMD patients, but also a ‘provocative’ tool, so its application should always be monitored by electromyographic and electrognathographic analysis (before and after TENS). Conclusions: Further clinical studies (mainly randomized controlled trials) on ULF–TENS application in neuromuscular gnathology are needed.

Low and high-frequency TENS in post-episiotomy pain relief: a randomized, double-blind clinical trial

ObjectiveTo evaluate the effectiveness of low-frequency TENS (LFT) and high-frequency TENS (HFT) in post-episiotomy pain relief. MethodA randomized, controlled, double-blind clinical trial with placebo composed of 33 puerperae with post-episiotomy pain. TENS was applied for 30 minutes to groups: HFT(100 Hz; 100 µs), LFT (5 Hz; 100 µs), and placebo (PT). Four electrodes were placed in parallel near the episiotomy and four pain evaluations were performed with the numeric rating scale. The first and the second evaluation took place before TENS application and immediately after its removal and were done in the resting position and in the activities of sitting and ambulating. The third and fourth evaluation took place 30 and 60 minutes after TENS removal, only in the resting position. Intragroup differences were verified using the Friedman and Wilcoxon tests, and the intergroup analysis employed the Kruskal-Wallis test. ResultsIn the intragroup analysis, there was no significant difference in the PT during rest, sitting, and ambulation (P>0.05). In the HFT and LFT, a significant difference was observed in all activities (P<0.001). In the intergroup analysis, there was a significant difference in the resting position in the HFT and LFT (P<0.001). In the sitting activity, a significant difference was verified in the second evaluation in the HFT and LFT (P<0.008). No significant difference was verified among the groups in ambulation (P<0.20). ConclusionsLFT and HFT are an effective resource that may be included in the routine of maternity wards.

Wound healing effect of TENS in rodents.

The aim of this study was to investigate the wound healing activity of low frequency and high frequency TENS on excision wound model in rats.Excision wound:Thirty rats, Wistar, 250–300 g were anesthetized and an excisional wound was performed. The animals was treated with placebo ‐ TENS simulation (equipment off), low‐frequency TENS (2 Hz) and high‐frequency TENS (100 Hz) for 7 days. The residual wounds were analyzed and removed. Experimental protocols were approved by the animal care and use committee at Federal University of Sergipe (CEPA 69/2011). Serial histological sections were obtained and stained by histochemical techniques (Hematoxilin‐Eosin – HE and Sirius red) and immunohistochemical techniques. The results suggest that the high‐frequency TENS reduced (p &lt; 0.05) wound areas. This evidence shows that high‐frequency TENS modulates the wound healing process.

Effect of transcutaneous electrical stimulation on nociception and edema induced by peripheral serotonin

Transcutaneous electrical nerve stimulation (TENS) is defined as the application of an electrical current to the skin through surface electrodes for pain relief. Various theories have been proposed in order to explain the analgesic mechanism of TENS. Recent studies have demonstrated that part of this analgesia is mediated through neurotransmitters acting at peripheral sites. The aim of this study was to investigate the effects of low frequency (LF: 10 HZ) TENS and high frequency (HF: 130 HZ) TENS on hyperalgesia and edema when applied before the serotonin (5-HT) administered into the rat paw. LF and HF TENS were applied to the right paw for 20 min, and 5-HT was administered immediately after TENS. The Hargreaves method was used to measure nociception, while the hydroplethysmometer (Ugo Basile®) was used to measure edema. Neither HF nor LF TENS inhibited 5-HT-induced edema. However, LF TENS, but not HF TENS, completely reduced 5-HT-induced hyperalgesia. Pre-treatment of the paw with naltrexone, prior to application of TENS, (Nx: 50μg; I.pl.) showed a complete blockade of the analgesic effect induced by low frequency TENS. Thus, our results confirmed the lack of an anti-inflammatory effect through the use of TENS as well as the participation of peripheral endogenous opioid receptors in LF TENS analgesia in addition to its central action.

The effect of low-frequency TENS in the treatment of neuropathic pain in patients with spinal cord injury

Prospective, randomized and controlled study. The aim of the study was to investigate the effect of low-frequency transcutaneous electrical nerve stimulation (LF-TENS) in the treatment of neuropathic pain in patients with spinal cord injury (SCI). A total of 33 SCI patients with neuropathic pain were included in the study. History, duration, localization and characteristics of pain were recorded. Visual analog scale (VAS) was used to investigate the effect of LF-TENS four times during the day. Patients were randomly assigned to study and control groups. The study group was treated with 30 min of LF-TENS daily for 10 days while the placebo group with 30 min of sham TENS. The mean age of the patients was 36.55±10.36 years. Out of 33 patients, 7 were tetraplegic and 26 were paraplegic. Twenty-three patients had complete SCI while 10 patients had incomplete injuries. Two groups were similar with respect to age, gender, duration, level and severity of injury. In the LF-TENS treatment group, a statistically significant reduction of the VAS values was observed, however, such an effect was not evident in the control group. This study revealed that in treatment of neuropathic pain of SCI patients, LF-TENS may be effective. This article presents LF-TENS may effectively complement pharmacological treatment in patients with SCI and neuropathic pain.

Comparative Study: Analgesic effect of Al-TENS in Variation of Treatment Time on Experimentally Induced Ischaemic Pain in Healthy Young Adult

Objective: To evaluate the effectiveness of acupuncture like-TENS in variation of time on experimentally induced ischaemic pain. Methods: 80 healthy subjects (40 female and 40 male) of age group between 18 to 28 years were randomly allocated to four groups A, B, C and placebo group D. After experimentally inducing ischaemic pain by sub maximal effort tourniquet technique (SMETT), followed by hand grip exercises, AL-TENS applied for 10 min in group A, 16 min in group B, 20 min in group C and 20 min placebo in group D. Baseline data obtained after induction of ischaemic pain. Measurements of pain intensity were obtained via the visual analogue scale (VAS). Result: The one-way analysis of variance (ANOVA) and post hoc ANOVA performed between groups comparison of the variables showed significant decrease in pain intensity score on VAS at 10 min and 16 min with placebo group but revealed no significant differences between groups at 18th and 20th minutes. Thus indicating application of AL-TENS for 10 minutes or 16 minutes is sufficient to produce hypoalgesic effect. Conclusion: Results of this study have indicated that low-frequency TENS (AL-TENS) has a greater hypoalgesic effect compared to placebo TENS on an experimental pain model which closely resemble to acute clinical pain. This study has also demonstrated that 10 minutes and 16 minutes are sufficient for application of acupuncture like TENS in producing its hypoalgesic effect.

Comparative evaluation of the direct analgesic efficacy of selected physiotherapeutic methods in subjects with knee joint degenerative disease – preliminary report.

The goals of the study were to evaluate the efficacy of two physiotherapeutic procedures: low energy laser therapy and low frequency transcutaneous electric nerve stimulation (TENS) and to compare these modalities with regard to their therapeutic effects in patients with knee osteoarthritis. Fifty (50) subjects were enrolled into the study and divided into two groups of 25 subjects. Group A received 10 MLS laser therapy sessions with a synchronised laser beam at doses of 12 J per treated site. Group B received ten sessions of low frequency TENS. The procedures were carried out every day for two weeks (5 times a week). All patients completed a personal data questionnaire and underwent an examination of knee joint motion range and circumference. Subjective pain intensity was assessed using the VAS pain scale and the modified Laitinen questionnaire. An analysis of the results of the treatment demonstrated statistically significant pain reduction in both groups. This improvement was significantly higher in the two-phase laser therapy group vs. the LF-TENS group. No statistically significant improvement was noted in either of the groups regarding the knee joint range of motion. 1. Synchronised laser beam (MLS) therapy and low-frequency TENS contribute to direct pain relief effects in subjects with knee osteoarthritis. 2. The study confirmed better analgesic effects of two-phase laser therapy vs. LF-TENS.

Functional Magnetic Resonance Imaging of the Effects of Low-frequency Transcutaneous Electrical Nerve Stimulation on Central Pain Modulation

Transcutaneous electrical nerve stimulation (TENS) is an analgesic current that is used in many acute and chronic painful states. The aim of this study was to investigate central pain modulation by low-frequency TENS. Twenty patients diagnosed with subacromial impingement syndrome of the shoulder were enrolled in the study. Patients were randomized into 2 groups: low-frequency TENS and sham TENS. Painful stimuli were delivered during which functional magnetic resonance imaging scans were performed, both before and after treatment. Ten central regions of interest that were reported to have a role in pain perception were chosen and analyzed bilaterally on functional magnetic resonance images. Perceived pain intensity during painful stimuli was evaluated using visual analog scale (VAS). In the low-frequency TENS group, there was a statistically significant decrease in the perceived pain intensity and pain-specific activation of the contralateral primary sensory cortex, bilateral caudal anterior cingulate cortex, and of the ipsilateral supplementary motor area. There was a statistically significant correlation between the change of VAS value and the change of activity in the contralateral thalamus, prefrontal cortex, and the ipsilateral posterior parietal cortex. In the sham TENS group, there was no significant change in VAS value and activity of regions of interest. We suggest that a 1-session low-frequency TENS may induce analgesic effect through modulation of discriminative, affective, and motor aspects of central pain perception.

Antihypertensive effect of low-frequency transcutaneous electrical nerve stimulation (TENS) in comparison with drug treatment

Hypertension is a major risk factor for vascular disease, yet blood pressure (BP) control is unsatisfactory low, partly due to side-effects. Transcutaneous electrical nerve stimulation (TENS) is well tolerated and studies have demonstrated BP reduction. In this study, we compared the BP lowering effect of 2.5 mg felodipin once daily with 30 min of bidaily low-frequency TENS in 32 adult hypertensive subjects (mean office BP 152.7/90.0 mmHg) in a randomized, crossover design. Office BP and 24-h ambulatory BP monitoring (ABPM) were performed at baseline and at the end of each 4-week treatment and washout period. Felodipin reduced office BP by 10/6 mmHg (p <0.001 respectively) and after washout BP rose to a level still significantly lower than at baseline. TENS reduced office BP by 5/1.5 mmHg (p <0.01, ns). After TENS washout, BP was further reduced and significantly lower than at baseline, but at levels similar to BP after felodipin washout and therefore reasonably caused by factors other than the treatment per se. ABPM revealed a significant systolic reduction of 3 mmHg by felodipin, but no significant changes were noted after TENS. We conclude that our study does not present any solid evidence of BP reduction of TENS.

Increase intensity in TENS prevent tolerance in rats

Transcutaneous electrical nerve stimulation (TENS) reduces hyperalgesia and pain through release of endogenous opioids in the central nervous system. Both low frequency (LF) and high frequency (HF) TENS, delivered at the same intensity (90% motor threshold (MT)) daily, results in analgesic tolerance with repeated use by the 5th day of treatment. Animals with TENS tolerance show a cross tolerance to opioid agonists in the spinal cord. The current study tested if 1) increasing intensity by 10% per day prevents the development of tolerance to repeated TENS, and 2) if lower intensity TENS produces an equivalent reduction in hyperalgesia when compared to 90% MT TENS.

TENS de alta e baixa frequência para dismenorreia primária: estudo preliminar

Introdução: Dismenorreia primária é conceituada como dor menstrual sem associação de patologias. Objetivo: Avaliar o efeito da eletroestimulação nervosa transcutânea (TENS) de alta e baixa frequência na redução do quadro álgico de mulheres com dismenorreia primária. Métodos: Realizou-se ensaio clínico preliminar, randomizado, controlado e duplo cego com 15 voluntárias com dismenorreia primária, divididas em três grupos: TENS alta frequência (TAF), TENS baixa frequência (TBF) e TENS placebo (TP). Na avaliação da dor e da limitação nas atividades diárias, utilizou-se a escala de categoria numérica. A avaliação da dor foi realizada antes e após a aplicação da TENS, que teve duração de 30 minutos. Foram utilizados testes estatísticos não paramétricos. O nível de significância foi p

Effects of Transcutaneous Electrical Nerve Stimulation on Pain, Pain Sensitivity, and Function in People With Knee Osteoarthritis: A Randomized Controlled Trial

Transcutaneous electrical nerve stimulation (TENS) is commonly used for the management of pain; however, its effects on several pain and function measures are unclear. The purpose of this study was to determine the effects of high-frequency TENS (HF-TENS) and low-frequency TENS (LF-TENS) on several outcome measures (pain at rest, movement-evoked pain, and pain sensitivity) in people with knee osteoarthritis. The study was a double-blind, randomized clinical trial. The setting was a tertiary care center. Seventy-five participants with knee osteoarthritis (29 men and 46 women; 31-94 years of age) were assessed. Participants were randomly assigned to receive HF-TENS (100 Hz) (n=25), LF-TENS (4 Hz) (n=25), or placebo TENS (n=25) (pulse duration=100 microseconds; intensity=10% below motor threshold). The following measures were assessed before and after a single TENS treatment: cutaneous mechanical pain threshold, pressure pain threshold (PPT), heat pain threshold, heat temporal summation, Timed "Up & Go" Test (TUG), and pain intensity at rest and during the TUG. A linear mixed-model analysis of variance was used to compare differences before and after TENS and among groups (HF-TENS, LF-TENS, and placebo TENS). Compared with placebo TENS, HF-TENS and LF-TENS increased PPT at the knee; HF-TENS also increased PPT over the tibialis anterior muscle. There was no effect on the cutaneous mechanical pain threshold, heat pain threshold, or heat temporal summation. Pain at rest and during the TUG was significantly reduced by HF-TENS, LF-TENS, and placebo TENS. This study tested only a single TENS treatment. Both HF-TENS and LF-TENS increased PPT in people with knee osteoarthritis; placebo TENS had no significant effect on PPT. Cutaneous pain measures were unaffected by TENS. Subjective pain ratings at rest and during movement were similarly reduced by active TENS and placebo TENS, suggesting a strong placebo component of the effect of TENS.

Comparison of Postoperative Analgesic Effects of Low Frequency TENS and Conventional TENS Used After Abdominal Hysterectomy

Comparison of Postoperative Analgesic Effects of Low Frequency TENS and Conventional TENS Used After Abdominal Hysterectomy

Transcutaneous electrical nerve stimulation at different frequencies on heart rate variability in healthy subjects

Sympathetic and parasympathetic nervous system imbalance has been strongly associated to sudden cardiac death. Among the non-pharmacological treatment, transcutaneous electrical nerve stimulation (TENS) represents a possible therapeutic intervention to reduce sympathetic excitation and improve the sympatho-vagal balance in different clinical conditions. We aimed to verify acute effects of high and low transcutaneous electrical nerve stimulation (TENS) frequencies by the evaluation of heart rate variability. Seven healthy volunteers received an application of low frequency (10-Hz) and high frequency (100-Hz) TENS. After 10-Hz, there was decrease of LF normalized units (n.u.) component (32.7±5.9 vs 18.3±3.4, p<0.002) and increase of HF n.u. (60.9±4.3 vs 72.6±8.9, p<0.016). In contrast, after 100-Hz there was increase of LF n.u. (31.5±16.1 vs 41.6±12.2, p<0.019) and reduction of HF n.u. (63.9±15.3 vs 53.7±12.3, p<0.031). In conclusion, TENS modulates sympathetic and parasympathetic activity in a frequency dependent manner.