Does TENS Reduce the Intensity of Acute and Chronic Pain? A Comprehensive Appraisal of the Characteristics and Outcomes of 169 Reviews and 49 Meta-Analyses

Background and Objectives: Uncertainty about the clinical efficacy of transcutaneous electric nerve stimulation (TENS) to alleviate pain spans half a century. There has been no attempt to synthesise the entire body of systematic review evidence. The aim of this comprehensive review was to critically appraise the characteristics and outcomes of systematic reviews evaluating the clinical efficacy of TENS for any type of acute and chronic pain in adults. Materials and Methods: We searched electronic databases for full reports of systematic reviews of studies, overviews of systematic reviews, and hybrid reviews that evaluated the efficacy of TENS for any type of clinical pain in adults. We screened reports against eligibility criteria and extracted data related to the characteristics and outcomes of the review, including effect size estimates. We conducted a descriptive analysis of extracted data. Results: We included 169 reviews consisting of eight overviews, seven hybrid reviews and 154 systematic reviews with 49 meta-analyses. A tally of authors’ conclusions found a tendency toward benefits from TENS in 69/169 reviews, no benefits in 13/169 reviews, and inconclusive evidence in 87/169 reviews. Only three meta-analyses pooled sufficient data to have confidence in the effect size estimate (i.e., pooled analysis of >500 events). Lower pain intensity was found during TENS compared with control for chronic musculoskeletal pain and labour pain, and lower analgesic consumption was found post-surgery during TENS. The appraisal revealed repeated shortcomings in RCTs that have hindered confident judgements about efficacy, resulting in stagnation of evidence. Conclusions: Our appraisal reveals examples of meta-analyses with ‘sufficient data’ demonstrating benefit. There were no examples of meta-analyses with ‘sufficient data’ demonstrating no benefit. Therefore, we recommend that TENS should be considered as a treatment option. The considerable quantity of reviews with ‘insufficient data’ and meaningless findings have clouded the issue of efficacy. We offer solutions to these issues going forward.

Shoulder transcutaneous electric nerve stimulation decreases heart rate via potentiating vagal tone

By enhancing vagal activity, auricle transcutaneous electric nerve stimulation (TENS) is developed as a non-invasive therapy for heart failure. Nevertheless, though shoulder TENS used for treating adhesive capsulitis could affect vagal tone, its potential impact on heart functions remains unclear. In this study, electrocardiogram (ECG) and heart rate (HR) of subjects in response to sham, right-sided, or left-sided shoulder TENS (TENS-S, TENS-R, and TENS-L, respectively; 5 min) were recorded and analyzed. During the stimulation period, TENS-R constantly and TENS-L transiently decreased the HR of subjects; both TENS-R and TENS-L increased powers of the low- and high-frequency spectra. While TENS-R exhibiting no effect, TENS-L increased the ratio of low/high-frequency power spectrum indicating TENS-R decreased the HR through potentiating cardiac vagal tone. Collectively, these results suggest TENS could be an early and non-invasive therapy for heart failure patients before considering implant devices or devices are not feasible; moreover, therapists/physicians need to carefully monitor the potential adverse events during treatment for patient safety.Trial registration: The study protocol was registered in ClinicalTrials.gov (NCT03982472; 11/06/2019).

Modest therapeutic effects of low-frequency transcutaneous electric nerve stimulation on insomnia among older adults: A 4-week multi-center, randomized controlled study

A 4-week, multi-center, randomized controlled study was conducted to evaluate the therapeutic efficacy and safety of low-frequency transcutaneous electric nerve stimulation (LF-TENS) for insomnia disorder. A total of 160 individuals aged 40 to 80 years with insomnia disorder were included and randomized to the experimental group receiving active device (n = 81) or control group receiving sham device (n = 79). Both groups used the device for four weeks, more than five days a week. The participants also completed pre- and post-intervention assessment with questionnaires, sleep diaries, wrist actigraphy, and blood tests. We found a significant improvement of subjective sleep quality, depressive/anxiety symptoms, and blood cortisol level in both experimental and control groups. Notably, among patients aged over 60 years, the experimental group showed better improvement after intervention in the change of PSQI score (2.60 ± 0.46 vs. 1.22 ± 0.46, p = 0.039; Cohen’s d = 0.99 vs 0.45) and blood cortisol level (-1.97 ± 0.53 µg/dl vs. -0.16 ± 0.53 µg/dl, p = 0.007; Cohen’s d = 0.56 vs 0.05). We found that LF-TENS was effective in improving subjective sleep quality in older adults aged over 60 years. The hypothalamic-pituitary-adrenal axis might be related to the therapeutic mechanism.

Peripheral Field Nerve Stimulation in Refractory Subcutaneous Persistent Postsurgical Pain

Background: The mechanistic underpinnings of nerve stimulation technology is an area of active debate in interventional pain literature. Whether the technology is transcutaneous, subcutaneous, or directly on the spinal cord/dorsal root ganglion, there are ample theories without substantive evidence. Although, these technologies have been proven to be invaluable for pain relief. Direct spinal cord stimulation is purported to be effective for peripheral pain through centrally mediated stimulation. However, in select cases, there is evidence for superior analgesia from a peripherally directed device, such as a subcutaneously placed peripheral field nerve stimulator (PFNS), when compared to spinal cord stimulators (SCS). Case Report: An 81-year-old man was referred for left upper thoracic pain exacerbated by lipoma excision with diagnostic imaging unsupportive of musculoskeletal etiology. The patient was found to have soft tissue tenderness to palpation worsened by activity. He failed numerous conservative treatments and procedures. An epidural SCS was trialed, with appropriate paresthesia mapping, but was unsuccessful in providing significant relief. Ultimately, a PFNS was trialed and found to provide adequate relief. A PFNS was later implanted, resulting in successful pain relief. Conclusion: The case demonstrates the importance of developing evidence-based guidelines for the application of PFNS. Additionally, it is important to delineate the shared and unique targets of nerve stimulator technologies so that patients may minimize risk through trial-and-error procedures. Key words: Surgical procedures, operative, spinal cord stimulation, refractory pain, paroxysmal nerve pain, intractable pain, electric stimulation therapy, back pain without radiation,transcutaneous electric nerve stimulation

Ultra-low-frequency-transcutaneous electric nerve stimulation for recording cameo surface and detachable cheek plumpers for enhanced complete denture esthetics

Severely resorbed completely edentulous maxillary and mandibular arches from long-term complete edentulism may pose a treatment challenge for the treating prosthodontist. The loss of teeth, over a period of time, can lead to gross facial disfigurement and also has great psychological effect. The loss of teeth also has effect on the musculature and supporting tissues which may lead to muscle wasting and dystrophy. Ever since its introduction in 1971, Transcutaneous Electrical Nerve Stimulation (TENS) has been used in dentistry for various treatment modalities and it is especially indicated in management of tempo-mandibular dysfunctions (TMDs). TENS being a non-invasive, non-technique sensitive, and easy to use technique has evolved rapidly over the years as an adjunct in management of various dental therapies. Two case reports of completely edentulous patients are presented here, where ultra-low-frequency-TENS (ULF-TENS) was used as an aid in cameo surface recording and customizing the magnet retained cheek plumper within the physiological and functional limits of the orofacial musculature complex for rehabilitation with complete denture prosthesis.

Transcutaneous electrical nerve stimulation (TENS) in the management of post-thoracotomy pain: A systematic review

Introduction: Thoracotomy is considered one of the most painful operative procedures in surgical practice, and postoperative pain control is a challenge. Objectives: To evaluate transcutaneous electrical nerve stimulation (TENS) as a form of treatment for post-thoracotomy pain. Design and setting: A systematic review conducted at the Pontifical Catholic University of Goiás. Methods: A systematic literature review was performed in the PubMed and Lilacs databases with the terms: “Post-thoracotomy pain AND (Transcutaneous Electric Nerve Stimulation OR TENS)”, being selected randomized controlled trials, clinical trials and case reports. Studies that did not fit the objectives were excluded. Results: TENS was shown to be a safe and effective therapy in the management of acute post-thoracotomy pain in the emergency department; however, the technique did not decrease the length of hospital stay or early pulmonary complications. One such study pointed to decreased shoulder flexion pain in patients undergoing axillary thoracotomy for lung resection, with pain sensation significantly decreased in the experimental group. In consonance, other trials emphasized the importance of the association of TENS with pharmacological therapy already employed in the emergency department, because patients who received fentanyl and bupivacaine associated with TENS perceived an immediate reduction in pain intensity at rest. Conclusion: TENS has proven to be a very effective and safe therapy in the treatment of postoperative pain in patients undergoing thoracotomy, improving their quality of life and reducing the consumption of analgesics.