Transcutaneous Electrical Nerve Stimulation Stimulation Research Articles

Regulation of Cerebral Blood Flow Velocity by Transcutaneous Electrical Nerve Stimulation: A Preliminary Study

Objectives: An excessive and abrupt increase in cerebral blood flow may cause blood vessel damage, leading to stroke. Therefore, appropriate methods to immediately regulate blood flow velocity are important. Through an analysis of 31 healthy adults, we therefore investigated whether stimulating the common carotid artery (CCA) using transcutaneous electrical nerve stimulation (TENS) could modulate blood flow velocity in the CCA. Methods: Three stimulation intensities (below-threshold, threshold, and above-threshold) were applied in a random order. Blood velocity changes were examined by the measurement of peak systolic velocity (PSV) with Doppler ultrasound before, during, and after TENS stimulation. To evaluate arterial stiffness, pulse wave velocity (PWV) was calculated using CCA diameter, and blood pressure was measured before and after stimulation. Results: PSV changes in the below-threshold level were significant (p = 0.028). The PSV after below-threshold stimulation was significantly decreased by 2.23% compared to that before stimulation (p = 0.031). PWV showed no significant differences; however, a nonsignificant increase was observed immediately after stimulation only in the above-threshold condition. Above-threshold stimulation can increase vascular tone by activating the sympathetic nerve, possibly triggering vasoconstriction. Conclusions: A decrease in blood flow velocity may not be expected upon the above-threshold stimulation. In contrast, the below-threshold stimulation immediately reduces blood flow velocity, without significantly affecting hemodynamic function, such as arterial flexibility. Therefore, this short-term and low electrical stimulation technique can help to lower vascular resistance and prevent vascular damage from rapid blood flow velocity.

Decreasing the blood flow of non-compressible intra-abdominal organs with non-invasive transcutaneous electrical stimulation

Non-invasive neuromodulation of non-compressible internal organs has significant potential for internal organ bleeding and blood-shift in aero/space medicine. The present study aims to investigate the potential influences of the non-invasive transcutaneous electrical nerve stimulation (TENS) on multiple non-compressible internal organs’ blood flow. Porcine animal model (n = 8) was randomized for a total of 48 neuromodulation sessions with two different TENS stimulation frequencies (80 Hz, 10 Hz) and a placebo stimulation. A combination of two different electrode configurations (Abdominal-only or Abdominal and hind limb) were also performed. Intraarterial blood flow measurements were taken during pre and post-stimulation periods at the left renal artery, common hepatic artery, and left coronary artery. Intracranial, and extracranial arterial blood flows were also assessed with digital subtraction angiography. TENS with abdominal-only electrode configurations at 10 Hz demonstrated significant reductions in average peak blood flow velocity (APV) of the common hepatic artery (p = 0.0233) and renal arteries (p = 0.0493). Arterial pressures (p = 0.0221) were also significantly lower when renal APV was reduced. The outcome of the present study emphasises the potential use of TENS in decreasing the blood flow of non-compressible internal organs when the correct combination of electrodes configuration and frequency is used.

Impact of TENS stimulation on acute postoperative pain after abdominal surgery—a pubmed review

Transcutaneous electrical nerve stimulation (TENS) is a technique in which pulsed low-voltage electrical currents are delivered through electrodes applied on the intact skin surface of the painful area of the body, by using a special device in order to stimulate peripheral nerves including those for pain relief. This method is used to manage acute and chronic pain, conditions of nociceptive or neuropathic origin. All clinical trials with TENS for postoperative acute pain were included. Case reports, reviews, protocols, letters to the editor, animal experimental research, guidelines, and ongoing or uncompleted trials were excluded. Two hundred fifty-two articles involving postoperative pain and transcutaneous electric nerve stimulation were identified by applying the aforementioned search strategy which resulted in including 18 articles in the analysis. The number of patients assessed for eligibility in each article varies from a maximum of 800 to a minimum of 3. In 88.89% of the articles the frequency of the TENS applied in the patients was mentioned. In half of the research performed in the selected articles pain was evaluated with the visual analogue scale. Immediate postoperative active mobilization of the patient is a key point of shortening the convalescence period and hospitalisation, the one individual in cause being able to attend work and social activities as soon as possible therefore being able to discover non-invasive, simple to use methods that reduce pain overall and the consumption of pharmaceutical analgesics is mandatory. The TENS technique is a non-invasive, safe, complementary technique used in order to reduce acute postoperative pain and improve pulmonary function, especially deep breathing, facilitating active movement and recovery of the patient and significant morbidity reduction.

Evaluation of TENS Based Biofeedback and Warning for Improvement of Seated Balance on a Trunk Rehabilitation Robot

Provision of visual feedback under unstable and forcefully perturbed seat conditions can help improve seated balance performance. However, due to visual limitations, some patients may require use of a different modality. Additionally, warning about an upcoming perturbation may improve balance reactions, and use of a system that provides such warnings and balance biofeedback through different modalities may result in further improvement. Transcutaneous electrical nerve stimulation (TENS), which can generate electro-tactile stimulation, may be useful in this regard. Therefore, in this study with 21 healthy subjects, we have used our recently developed trunk rehabilitation robot to evaluate the performance of TENS as a feedback and perturbation warning modality against visual and vibrotactile stimulation. The center of pressure (COP) and trunk acceleration results show that both TENS and vibrotactile stimulation may serve as viable alternatives for visual feedback under unstable condition. Under perturbation condition, provision of warning improves balancing performance, and TENS shows the overall best performance as a warning modality, with vibrotactile showing the lowest performance. Thus, TENS may be considered a feasible feedback/warning modality for use during seated balance rehabilitation.

EEG Features of Evoked Tactile Sensation: Two Cases Study.

Purpose: Sensory feedback for prosthetics is an important issue. The area of forearm stump skin that has evoked tactile sensation (ETS) of fingers is defined as the projected finger map (PFM), and the area close to the PFM region that does not have ETS is defined as the non-projected finger map (NPFM). Previous studies have confirmed that ETS can restore the tactile pathway of the lost finger, which was induced by stimulation of transcutaneous electrical nerve stimulation (TENS) on the end of stump skin. This study aims to reveal EEG features between the PFM and the NPFM regions of the stumps under the same TENS stimulation condition.Methods: The PFM and NPFM regions of the two subjects were stimulated with the same intensity of TENS, respectively. TENS as target stimuli are modulated according to the Oddball paradigm to evoke the P300 components.Result: The PFM regions of both subjects were able to elicit P300 components, while their NPFM regions were not able to elicit P300 components. However, this P300 appears early (249 ms for subject 1,230 ms for subject 2) and has continuous positive peaks (peak 1,139 ± 3 ms, peak 2,194 ± 0.5 ms) in front of it.Discussion: N30 and P300 can prove that the two subjects with PFM can perceive and recognize ETS. The heteromorphisms of the P300 waveform may be related to the difficulty in subjects’ cognition of ETS or caused by the fusion of P150, P200, and P300.

Somatosensory Cortex Repetitive Transcranial Magnetic Stimulation and Associative Sensory Stimulation of Peripheral Nerves Could Assist Motor and Sensory Recovery After Stroke.

BackgroundWe investigated whether transcranial magnetic stimulation (rTMS) over the primary somatosensory cortex (S1) and sensory stimulation (SS) could promote upper limb recovery in participants with subacute stroke.MethodsParticipants were randomized into four groups: rTMS/Sham SS, Sham rTMS/SS, rTMS/SS, and control group (Sham rTMS/Sham SS). Participants underwent ten sessions of sham or active rTMS over S1 (10 Hz, 1,500 pulses, 120% of resting motor threshold, 20 min), followed by sham or active SS. The SS involved active sensory training (exploring features of objects and graphesthesia, proprioception exercises), mirror therapy, and Transcutaneous electrical nerve stimulation (TENS) in the region of the median nerve in the wrist (stimulation intensity as the minimum intensity at which the participants reported paresthesia; five electrical pulses of 1 ms duration each at 10 Hz were delivered every second over 45 min). Sham stimulations occurred as follows: Sham rTMS, coil was held while disconnected from the stimulator, and rTMS noise was presented with computer loudspeakers with recorded sound from a real stimulation. The Sham SS received therapy in the unaffected upper limb, did not use the mirror and received TENS stimulation for only 60 seconds. The primary outcome was the Body Structure/Function: Fugl-Meyer Assessment (FMA) and Nottingham Sensory Assessment (NSA); the secondary outcome was the Activity/Participation domains, assessed with Box and Block Test, Motor Activity Log scale, Jebsen-Taylor Test, and Functional Independence Measure.ResultsForty participants with stroke ischemic (n = 38) and hemorrhagic (n = 2), men (n = 19) and women (n = 21), in the subacute stage (10.6 ± 6 weeks) had a mean age of 62.2 ± 9.6 years, were equally divided into four groups (10 participants in each group). Significant somatosensory improvements were found in participants receiving active rTMS and active SS, compared with those in the control group (sham rTMS with sham SS). Motor function improved only in participants who received active rTMS, with greater effects when active rTMS was combined with active SS.ConclusionThe combined use of SS with rTMS over S1 represents a more effective therapy for increasing sensory and motor recovery, as well as functional independence, in participants with subacute stroke.Clinical Trial Registration[clinicaltrials.gov], identifier [NCT03329807].

Effectiveness of Transcutaneous Electrical Nerve Stimulation with Taping for Stroke Rehabilitation

Background Spasticity is a factor that impairs the independent functional ability of stroke patients, and noninvasive methods such as electrical stimulation or taping have been reported to have antispastic effects. The purpose of this study was to investigate the effects of transcutaneous electrical nerve stimulation (TENS) combined with taping on spasticity, muscle strength, and gait ability in stroke patients. Methods From July to October 2020, 46 stroke patients with moderate spasticity in the plantar flexors participated and were randomly assigned to the TENS group (n = 23) and the TENS+taping group (n = 23). All subjects performed a total of 30 sessions of functional training for 30 min/session, 5 days/week, for 6 weeks. For therapeutic exercise, sit-to-standing, indoor walking, and stair walking were performed for 10 min each. In addition, all participants in both groups received TENS stimulation around the peroneal nerve for 30 min before performing functional training. In the TENS+taping group, taping was additionally applied to the feet, ankles, and shin area after TENS, and the taping was replaced once a day. The composite spasticity score and handheld dynamometer measurements were used to assess the intensity of spasticity and muscle strength, respectively. Gait ability was measured using a 10 m walk test. Results The spasticity score and muscle strength were significantly improved in the TENS+taping group compared to those in the TENS group (p < 0.05). A significant improvement in gait speed was observed in the TENS+taping group relative to that in the TENS group (p < 0.05). Conclusions Thus, TENS combined with taping may be useful in improving spasticity, muscle strength, and gait ability in stroke patients. Based on these results, an additional application of taping could be used to enhance the antispastic effect of TENS or other electrical stimulation treatments in the clinic. A long-term follow-up study is needed to determine whether the spasticity relieving effect persists after taping is removed.

Electroacupuncture and Transcutaneous Electrical Nerve Stimulation Induced Sensations in Bell's Palsy Patients: A Quantitative Current Intensity Analysis.

BackgroundThe intensity of electrical acupoint stimulation such as electroacupuncture (EA) and transcutaneous electrical nerve stimulation (TENS) is regulated by the observation of skin shivering or the participant’s comfort response. However, the specific intensity and spatial scope following EA or TENS stimulation are unclear.ObjectiveThis study aimed to test the stimulatory current intensities of lower and upper sensation thresholds in TENS- and EA-based treatment of Bell’s palsy patients. Also, the spatial scope of the stimulation at these current intensities was simulated and measured quantitatively.MethodsA total of 19 Bell’s palsy patients were recruited. Six acupoints on the affected side of the face were stimulated by TENS and EA successively at 30-min intervals. During the stimulation, the current intensity was regulated gradually from 0 to 20 mA, and we simultaneously measured the lower (sensory) and upper (tolerability) sensations. After the treatment by TENS and EA, the modified Chinese version of the Massachusetts General Hospital Acupuncture Sensation Scales (C-MMASS) was applied to survey the de-qi sensations during stimulation. Additionally, we analyzed the correlation between current intensities and C-MMASS and comfort scores. Finite element models were established to depict the spatial distribution of electric field gradients at the lower and upper thresholds.ResultsThe mean sensory and tolerability thresholds of TENS were 3.91–4.37 mA and 12.33–16.35 mA, respectively. The median sensory and tolerability thresholds of EA were 0.2 mA and 2.0–3.2 mA, respectively. We found a significant correlation between total C-MMASS scores and the current intensities at the tolerability threshold of TENS. The finite element model showed that the activated depths of TENS and EA at the lower threshold were 3.8 and 7 mm, respectively, whereas those at the upper threshold were both 13.8 mm. The cross-sectional diameter of the activated area during TENS was 2.5–4 times larger than that during EA.ConclusionThis pilot study provided a method for exploring the current intensity at which the de-qi sensations can be elicited by TENS or EA. The finite element analysis potentially revealed the spatial scope of the electrical stimulation at a specific current intensity.

Immediate effects of TENS and HVPS on pain and range of motion in subacromial pain syndrome: A randomized, placebo-controlled, crossover trial.

Transcutaneous electrical nerve stimulation (TENS) is one of the most common methods for managing shoulder pain, and high voltage pulsed currents (HVPS) may be used for reducing pain. However, their immediate effects on resting pain and pain-free active range of shoulder motion (pfROM) in patients with subacromial pain syndrome (SAPS) have not been studied comparatively, yet. The aim of this study was to compare the immediate effects of TENS, HVPS and placebo stimulation on shoulder resting pain and pfROM in patients with SAPS. Randomized, placebo-controlled, double-blind, crossover study. One hundred and six patients with SAPS received placebo (predetermined 1st day application), TENS and HVPS with 1-day interval, in a random sequence. Before and after each application, resting pain and pfROM were evaluated by 0-10 cm visual analogue scales and a digital inclinometer, respectively. Intensity of pain decreased significantly after TENS, HVPS and placebo interventions (p< 0.05). While pfROMs increased significantly after TENS and HVPS (p< 0.05), remained unchanged after placebo, except for internal and external rotations (p> 0.05). The most obvious effects on pain and pfROMs occurred after HVPS (p< 0.05). In patients with SAPS, both HVPS and TENS, but preferably HVPS can be used effectively to decrease pain and increase pfROM.

Effectiveness of Low-Frequency Stimulation in Proprioceptive Neuromuscular Facilitation Techniques for Post Ankle Sprain Balance and Proprioception in Adults: A Randomized Controlled Trial.

Stretching is an important part of post ankle sprain rehabilitation, as well as an effective exercise for improving general ankle-joint performance. But the combination of stretching alongside low-frequency stimulation has not yet been extensively studied. Therefore, the purpose of the present randomized controlled trial was to compare the combined effects of low-frequency transcutaneous electrical nerve stimulation (TENS) with proprioceptive neuromuscular facilitation (PNF) on strength, balance, and proprioception among individuals with post ankle sprain. Sixty male subjects with lateral ankle sprain were selected and randomly allocated to three groups: group 1, group 2, and the control group (CG). Subjects in group 1 received the PNF stretching technique combined with TENS. TENS stimulation was provided using two electrodes placed 5 cm apart directly on the triceps sural muscle of the affected leg and a biphasic current with a symmetrical waveform at 50 Hz for 15 seconds, tuned for a 3-second ramp up time and a 30-second rest time with a 250-microsecond pulse duration was given with PNF stretching. Subjects in group 2 received the PNF stretching technique alone. Both group 1 and group 2 received these treatments for 4 weeks (4 days/week); follow-up assessments were administered in the third and fifth weeks. CG received no treatment; outcome measures alone were assessed. Outcome measures comprised pain, balance, flexibility, proprioception, range of motion, muscle strength, and functional limitation. A mixed-model ANOVA showed significant interaction (time and group) and the time effect for all the outcome measures (p ≤ 0.05). Group 1 (PNF-TENS) showed significant improvement for all the outcome variables compared to the other groups. The present study showed PNF stretching combined with TENS for the triceps sural muscle to trigger muscle contraction during the muscle contraction phase of the PNF stretch, compared against PNF stretching alone, produced significant improvements in ankle function for post ankle sprain subjects.

Cortical connectivity and spectral perturbations underlying TENS stimulation of hand nerves: a case study.

The major challenge in upper limbs neuroprosthetic improvement is the implementation of effective sensory feedback. Transcutaneous electrical nerve stimulation (TENS) of the median and ulnar nerves confirmed, with electroencephalographic (EEG) recordings, the presence of appropriate responses in relevant cortical areas with induced sensation successfully located in the innervation regions of each nerve. The characterization of these elicited responses could be used to recreate precise somatotopic feedback from hand protheses. Using TENS and EEG, the purpose of this study was to detect distinctions in time-frequency cortical dynamics and connectivity occurring after stimulation of hand nerves. Region of interest (ROI) were selected according to topographical distributions and Somatosensory Evoked Potentials (SEP) localization and were named Contralateral Parietal (Cont P), Central Frontal (Cent F) and Superior Parietal (Sup P). The analysis of cortical oscillations showed spectral inflections in theta [4-7 Hz] and alpha [7.5-12.5 Hz] band which occurred at 60 ms in Cont P and 300 ms in Sup P and prominent for the ulnar condition over the median one. The beta band decrease [16-30 Hz] which occurred in the same ROIs was especially significant after ulnar stimulation too. Effective connectivity measures did not differ significantly across conditions but exhibited some slight difference in the alpha-band causal flow coming from Cent F in direction to Cont P and Sup P. Although pending completion of multiple-subjects study, these results already suggest magnitude differences in somatosensory spectral fluctuations and sensorimotor interactions flows.

Sensory Sub- and Suprathreshold TENS Exhibit No Immediate Effect on Postural Steadiness in Older Adults with No Balance Impairments.

Transcutaneous electrical nerve stimulation (TENS) has been reported to attenuate postural sway; however, the results are inconclusive, with some indicating the effect and others not. The study aimed to evaluate the effect of sensory sub- and suprathreshold low-frequency TENS applied through the plantar surface and posterior aspect of shanks on postural sway. In a group of healthy community-dwelling older adults, TENS was delivered with two different current intensities: (1) subsensory which is below conscious perception and (2) suprasensory threshold which is within the range of conscious perception. Frequencies of the TENS stimulation were sweeping from 5 to 180 Hz and were delivered through the plantar surface and posterior shanks of both legs. Postural sway was measured with a force platform in eyes-open and eyes-closed conditions. To evaluate potential fast adaptability to TENS stimuli, the results were evaluated in two time intervals: 30 seconds and 60 seconds. The results indicated that TENS with the chosen frequencies and electrode placement did not affect postural sway in both the sub- and suprathreshold intensities of TENS, in eyes-open and eyes-closed conditions, and in 30-second and 60-second time intervals. In conclusion, given that in this study sub- and suprathreshold TENS applied via the plantar surface of the feet did not attenuate postural sway, it would be easy to conclude that this type of electrical stimuli is ineffective and no further research is required. We must caution against this, given the specificity of the electrode placements. We recommend that future research be performed consisting of individuals with balance impairments and with different positions of electrodes.

Design and Evaluation of a Modulated TENS Stimulation in Medical Pain Therapy

Background: Transcutaneous Electrical Nerve Stimulation (TENS) is a non-invasive pain therapy that uses the sensory effects of an electrical current applied to the skin. Some clinical studies demonstrated that this treatment helps to reduce acute and chronic pains, while others gave sometimes contradictory or uncertain conclusions about the performances of this strategy according to pathology classification. The purpose of this study is the development and evaluation of a new modulated version of transcutaneous electrical nerve stimulation called PWM-TENS. The principle is based on an automatic variation of the stimulation parameters (frequency, amplitude, duration, shape, cyclic ratio) according to the pain evolution. Methods: The study was a controlled clinical trial involving 15 participants, divided into 2 groups. The first experimental group performed modulated PWM-TENS electro-stimulation sessions applied to the painful areas 3 to 4 times a day, for one month. The second control group did parallel treatments by Placebo. The evaluation of the pain intensity is done with the Visual Analog Scale (EVA), the DN4 and SF36 questionnaires. Results: The tests and measurements with our embedded PWM-TENS technique demonstrated that we succeeded to increase the analgesic effect after stopping the stimulation and reduced the pain sensation by about 60%. An improvement in pain intensity scores and questionnaires (EVA, DN4), as well as the quality of life score (SF36), was observed. Also, a reduction of the treatment period from 3 to 1 month was also obtained. Conclusion: The first results clinically observed in the PWM-TENS technique are encouraging. The findings of this study confirm that this noninvasive strategy is suitable and useful for acute pains coming from the nociceptive, neuropathic and musculoskeletal origin. However, its efficiency is moderated and less adapted for low back pain. The experiments make it possible to estimate whether this modulated TENS method could improve existing anti-pain therapies, taking into account objective and subjective evaluation criteria. But this study must be followed by large population samples to answer all the problems of acute and chronic pains.

Soleus H-reflex modulation following transcutaneous high- and low-frequency spinal stimulation in healthy volunteers

The main aim of this work was to investigate the difference in the excitability of the soleus H-reflex in healthy volunteers following spinal transcutaneous electrical nerve stimulation (TENS) and high-frequency alternating current (HFAC) at a frequency of 10 kHz applied at the lower thoracic spinal level (T10–T12). A double-blind, randomized, crossover, controlled clinical trial was designed. Participants received three randomized interventions (TENS, 10 kHz, and sham stimulation) during 40 min. The amplitude and latency of the soleus H-reflex were registered prior to, during, and 10 min following stimulation. Twenty-four participants completed the study. A significant inhibition of H-reflex amplitude was observed following transcutaneous spinal TENS (12.7%; 95% CI 1.5–22.2%) when compared with sham stimulation (5.5%; 95% CI 3.6–14.5%; p = 0.03). An increase in H-reflex latency was also observed following transcutaneous spinal stimulation at 10 kHz (2%; 95% CI 1.4–2.5%) as compared with sham stimulation (0.7%; 95% CI 0.07–1.3%; p < 0.01). No differences were found between TENS and 10 kHz for H-reflex modulation. Transcutaneous spinal TENS and HFAC at a frequency of 10 kHz had a modulatory effect on the soleus H-reflex when compared to sham stimulation; however, no differences were found between these two interventions.

Effect of different doses of low-intensity laser therapy on total active range of motion after hand flexor tendon repair

Objective To investigate the difference between the effects of different doses of low-level laser therapy (4 or 1 J/cm2) on the return of hand active range of motion (ROM) after flexor tendon repair. Participants and methods A small trial was conducted on 33 patients with 45 injured fingers of both sexes who underwent primary repair after complete cut of hand flexor tendon. Their age ranged from 20 to 40 years old. They were recruited from the plastic surgery department. The treatment began the first day postoperatively after permission by surgeons using Duran protocol and splinting. Transcutaneous electrical nerve stimulation (TENS), as well as LASER therapy, was started the seventh day after surgery. Laser treatment lasted for 3 weeks only, whereas other modalities lasted for 3 months. The sample was randomly divided into three groups each of 15 injured tendons. Group A received the conventional treatment plus laser therapy (1 J/cm2), three sessions/week for 3 weeks. Group B received the traditional treatment plus laser therapy (4 J/cm2), three sessions/week for 3 weeks. Control group received the conventional treatment only. All patients received the early conventional physical therapy after permission by the surgeon: TENS plus early therapeutic exercises following Duran protocol, three sessions/week for 3 months. The ROM was measured at eighth and 12th week after the commencement of treatment. Results At second month after commencement of treatment, there was a positive effect of laser therapy with either doses 1 or 4 J/cm2 on total hand active ROM after flexor tendons repair, with more effect noticed in group B (4 J/cm2). At third month after commencement of treatment, best results in hand active ROM were seen in group B (4 J/cm2), with prognosis being excellent in 46.7% of patients, good in 33.3% and fair in 20.0% according to the modified Strickland classification. Conclusion The 4-J/cm2 laser dose is more efficient than laser dose of 1 J/cm2 in the treatment of repaired hand flexor tendons in addition to conventional treatment (TENS stimulation plus Duran protocol therapeutic exercises) in early regain of active ROM that can affect return of early better hand function.

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

IntroductionTranscutaneous 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.ObjectivesOur 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.MethodsWomen 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.ResultsThere 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.ConclusionThe 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.

Intensity matters: Therapist-dependent dose of spinal transcutaneous electrical nerve stimulation.

The intensity used during transcutaneous electrical nerve stimulation (TENS) in both, clinical practice and research studies, is often based on subjective commands such as “strong but comfortable sensation”. There is no consensus regarding the effectiveness dose of TENS. The objective was to determine the difference in the effect of spinal TENS on soleus H-reflex modulation when applied by two therapists instructed to apply the stimulation at a “strong but comfortable” intensity. Twenty healthy volunteers divided into two groups: Therapist 1 (n = 10) and Therapist 2 (n = 10). Both therapist applied spinal TENS and sham stimulation at the T10–12 spinal level for 40min in random order to each subject, at an intensity designed to produce a “strong but comfortable” sensation. To avoid habituation, the intensity was adjusted every 2min. Soleus H-reflex was recorded before, during, and 10min after TENS by an observer blinded to the stimulus applied. Despite the instruction to apply TENS at a “strong comfortable” level, a significant difference in current density was identified: Therapist 1 (0.67mA/cm2, SD 0.54) applied more than Therapist 2 (0.53mA/cm2, SD 0.57; p<0.001) at the onset of the intervention. Maximal peak-to-peak H-reflex amplitude was inhibited significantly more 10min following TENS applied by Therapist 1 (-0.15mV, SD 0.16) compared with Therapist 2 (0.04mV, SD 0.16; p = 0.03). Furthermore, current density significantly correlated with the inhibitory effect on peak-to-peak Soleus H-reflex amplitude 10 min after stimulation (Rho = -0.38; p = 0.04). TENS intensity dosage by the therapist based on the subjective perception of the participants alone is unreliable and requires objective standardization. In addition, higher current density TENS produced greater inhibition of the Soleus H-reflex.

Nocebo-induced modulation of cerebral itch processing – An fMRI study

It has been shown repeatedly that perceiving itch-related pictures or listening to a lecture on itch can enhance itch sensation and scratching behaviour (Niemeier and Gieler, 2000; Holle et al., 2012; Lloyd et al., 2013), indicating that itch is strongly influenced by expectations. Using fMRI, we investigated the neural correlates of the itch-related nocebo effect in healthy male and female human subjects. Itch sensation on the left forearm was induced by cutaneous histamine application and thermally modulated, with cooling leading to higher itch. Nocebo-induced aggravation of histaminergic itch was achieved by ostensibly treating volunteers with “transcutaneous electrical nerve stimulation (TENS)” about which subjects were instructed that it would increase itch. During a conditioning phase subjects indeed experienced stronger itch due to slightly altered cooling and histamine concentrations, but attributed it to the alleged “TENS stimulation”. Importantly, in the subsequent test phase where no “TENS” or electrical stimulation was applied, volunteers significantly reported stronger itch during the nocebo as compared to the control condition.Comparing BOLD responses during nocebo in contrast to control, we observed increased activity in contralateral (right) rolandic operculum. Opercular involvement was repeatedly reported in studies related to the expectation of stimulus intensification and might thus represent an early area integrating expectation information with somatosensory information. Finally, functional coupling between the insula and the periaqueductal gray (PAG) was enhanced specifically in the nocebo condition. This cortex-PAG interaction indicates that context-dependent top-down modulation during itch might represent a shared mechanism with other modalities such as pain.

Differential efficiency of transcutaneous electrical nerve stimulation in dominant versus nondominant hands in fibromyalgia: placebo-controlled functional near-infrared spectroscopy study.

Using functional near-infrared spectroscopy (fNIRS), modulation of hemodynamic responses by transcutaneous electrical nerve stimulation (TENS) during delivery of nociceptive stimulation was investigated in fibromyalgia (FM) patients and healthy controls for both hands. Two experiments were conducted: (1)median nerve stimulation with TENS and (2)painful stimulation using electronic von Frey filaments with TENS/placebo TENS. Mean [Formula: see text] brain activity was compared across groups and conditions using factorial ANOVA. Dominant (right) hand stimulation indicated significant interactions between group and condition in both hemispheres. Post hoc results revealed that FM patients showed an increased activation in "pain + TENS" condition compared to the "pain + placebo TENS" condition while the brain activity patterns for these conditions in controls were reversed. Left-hand stimulation resulted in similar TENS effects (reduced activation for "pain + TENS" than "pain + placebo TENS") in both groups. TENS effects in FM patients might be manipulated by the stimulation side. While the nondominant hand was responsive to TENS treatment, the dominant hand was not. These results indicate that stimulation side might be an effective factor in FM treatment by using TENS. Future studies are needed to clarify the underlying mechanism for these findings.

The Effect of Frequency of Transcutaneous Electrical Nerve Stimulation (TENS) on Maximum Multi-finger Force Production

Objective: The purpose of this study was to investigate the effect of transcutaneous electrical nerve stimulation (TENS) treatment on maximum voluntary force (MVF) production. Methods: Ten healthy, young subjects (5 males and 5 females) participated in the study. MVF was recorded after a fifteen minute session of TENS stimulation under two conditions: low frequency (4 Hz) at maximum tolerable level and high frequency (110 Hz) at maximum tolerable level. TENS was provided simultaneously via self-adhesive electrodes placed on the finger pads of the index, middle, ring and little fingers. MVF was also recorded in a baseline condition with no TENS treatment. Data were collected in three different sessions on three consecutive days at the sametime of the day. Results: Results from the study show that on an average, MVF increasesby 25% for the index, middle and little fingers for TENS treatment with 4 Hz frequency as compared to the baseline condition. However, the 110 Hz condition did not result in a significantly different MVF than the baseline condition during individual finger pressing tasks. In addition, while producing MVF with all the four finger stogether, MVF was 30% higher for the 4 Hz conditionin comparison to the baseline condition, and 15% higher for the 110 Hz condition in comparison to the baseline condition respectively. Conclusion: The results suggest that stimulation ofafferent fibers onthe glabrous skinwith TENS could have a net facilitatory effect on the maximum motoroutput.