Electrical Stimulation Of Tibial Nerve Research Articles

Posterior tibial nerve electrical stimulation in chronic constipation: a systematic review and meta-analysis.

A systematic review and meta-analysis were performed to investigate posterior tibial nerve electrical stimulation application methods in patients with chronic constipation. Posterior tibial nerve electrical stimulation is a management procedure for chronic constipation. A comprehensive search was conducted on Ovid, PubMed, Scopus, ProQuest, Web of Science, and The Cochrane Library based on the PICO formation of the study. All randomized controlled trials and quasi-experimental studies in which patients with chronic constipation were treated with transcutaneous tibial nerve stimulation (TTNS) or percutaneous tibial nerve stimulation (PTNS) were included in this study. Two independent reviewers screened all titles, abstracts, and full texts. The selected studies' quality was assessed critically using the Joanna Briggs Institute checklists. The data synthesis was conducted using Review Manager Software. Out of 1016 records, 11 studies were included in this study. The results showed that TTNS was effective in improving constipation symptoms (SMD: -1.52, CI 95%: -2.81 to -0.22, p< 0.0001) and reducing defecation time of patients with chronic constipation (SMD: -0.86, CI 95%: -1.60 to -0.13, p= 0.17). Additionally, PTNS was found to improve the quality of life of these patients (SMD: -1.32, CI 95%: -2.05 to -0.59, p< 0.00001). Both TTNS and PTNS can be effective interventions for chronic constipation. To suggest a definitive and standard treatment plan, further research is needed to determine optimal parameters for TTNS and PTNS applications.

Relation of leg phase angle from bioelectrical impedance analysis with voluntary and evoked contractile properties of the plantar flexors

Introduction: Bioelectrical impedance analysis (BIA) can noninvasively and quickly assess electrical properties of the body, such as the phase angle. Phase angle is regarded as the quantity and/or quality of skeletal muscle and is associated with exercise performance, such as jump height and walking speed. Although the phase angle derived from BIA is assumed to be a useful way to assess muscle function, the relationship between the phase angle and neuromuscular properties has not been fully investigated. The purpose of this study was to investigate the association of phase angle with voluntary and evoked contractile properties in 60 adults (age, 21–83 years; 30 females and 30 males).Methods: The phase angle of the right leg at 50 kHz was evaluated using BIA. The twitch contractile properties (peak twitch torque [PTtwitch], rate of twitch torque development [RTDtwitch], and time-to-PTtwitch [TPTtwitch]) of the plantar flexors were measured using tibial nerve electrical stimulation. Maximal voluntary isometric contractions (MVICs) were performed to measure the maximal muscle strength and explosive muscle strength, from which the peak MVIC torque (PTMVIC) and rate of torque development (RTD) over a time interval of 0–200 ms were assessed, respectively. The root mean square (RMS) values of electromyographic (EMG) activity during the PTMVIC and RTD measurements (EMG-RMSMVIC and EMG-RMSRTD, respectively) were calculated. The RTD and EMG-RMSRTD were normalized using PTMVIC and EMG-RMSMVIC, respectively.Results and discussion: Phase angle significantly correlated with twitch contractile properties (|r| ≥ 0.444, p &amp;lt; 0.001), PTMVIC (r = 0.532, p &amp;lt; 0.001), and RTD (r = 0.514, p &amp;lt; 0.001), but not with normalized RTD (r = 0.242, p = 0.065) or normalized EMG-RMSRTD (r = −0.055, p = 0.676). When comparing measurement variables between the low- and high-phase angle groups while controlling for sex and age effects, the high-phase angle group showed greater PTtwitch, RTDtwitch, PTMVIC, and RTD (p &amp;lt; 0.001) and shorter TPTtwitch (p &amp;lt; 0.001) but not normalized RTD (p = 0.184) or normalized EMG-RMSRTD (p = 0.317). These results suggest that the leg phase angle can be an indicator of voluntary and evoked muscle contractile properties but not the neuromuscular activity of the plantar flexors, irrespective of sex and age.

Transcutaneous tibial nerve electrical stimulation versus vaginal electrical stimulation in women with overactive bladder syndrome: Is there a role for short-term interventions?

To assess the efficacy of vaginal electrical stimulation (VS) versus transcutaneous tibial nerve electrical stimulation (TTNS) in women with overactive bladder syndrome (OAB). Sixty-nine patients were randomized to receive 12 sessions of VS versus TTNS, or no treatment (control group-CG), over 6 weeks. OAB impact according to international consultation on incontinence questionnaire overactive bladder module (ICIQ-OAB), symptoms discomfort scores and voiding diaries were evaluated at baseline, 6 weeks and 1-month post-treatment. Both TTNS (mean difference = -4.2; 95% confidence interval [CI] = -6.5 to -1.9) and VS (-3.8; -6.0 to -1.6) were associated with significant reduction of ICIQ-OAB scores, as well as discomfort sensation (-3.9; -6.2 to -1,7; p < 0.001 for the TTNS and -2.8; -5.0 to -0.6; p = 0.01 for the VS) at 6 weeks when compared to CG (p < 0.001). ICIQ-OAB score remained low only in the TTNS group when compared to the CG (-3.6; -6.0 to -1.2/p = 0.00) 1 month after treatment. Discomfort symptoms improved in both active groups when compared to CG (TTNS [-3.2; -5.2 to -1.2; p < 0.001] and VS groups [-2.6; -4.7 to -0.6; p = 0.01]). No statistically differences were found in primary outcomes comparing TTNS and VS Secondary analysis showed significant improvement in urinary urgency incontinence episodes (UUI) in both TTNS and VS, but CG. UUI episodes were still reduced in the VS group and urgency in the TTNS group 1-month post-treatment. Short-term interventions (6 weeks) of TTNS and VS were both effective in treating women with OAB. TTNS provided residual effects at one-month postintervention on ICIQ-OAB score.

Disinhibition of short-latency but not long-latency afferent inhibition of the lower limb during upper-limb muscle contraction.

Research has demonstrated that motor and sensory functions of the lower limbs can be modulated by upper-limb muscle contractions. However, whether sensorimotor integration of the lower limb can be modulated by upper-limb muscle contractions is still unknown. [AQ: NR Original articles do not require structured abstracts. Hence, abstract subsections have been deleted. Please check.]Human sensorimotor integration has been studied using short- or long-latency afferent inhibition (SAI or LAI, respectively), which refers to inhibition of motor-evoked potentials (MEPs) elicited via transcranial magnetic stimulation by preceding peripheral sensory stimulation. In the present study, we aimed to investigate whether upper-limb muscle contractions could modulate the sensorimotor integration of the lower limbs by examining SAI and LAI. Soleus muscle MEPs following electrical tibial nerve stimulation (TSTN) during rest or voluntary wrist flexion were recorded at inter-stimulus intervals (ISIs) of 30 (i.e. SAI), 100, and 200 ms (i.e. LAI). The soleus Hoffman reflex following TSTN was also measured to identify whether MEP modulation occurred at the cortical or the spinal level. Results showed that lower-limb SAI, but not LAI, was disinhibited during voluntary wrist flexion. Furthermore, the soleus Hoffman reflex following TSTN during voluntary wrist flexion was unchanged when compared with that during the resting state at any ISI. Our findings suggest that upper-limb muscle contractions modulate sensorimotor integration of the lower limbs and that disinhibition of lower-limb SAI during upper-limb muscle contractions is cortically based.

Effects of Tibial Nerve Electrical Stimulation on Bowel Dysfunction in Multiple Sclerosis: A Systematic Review

Background: This study set out to conduct a thorough review of the effects of electrical tibial nerve stimulation in multiple sclerosis (MS) patients with bowel dysfunction. Methods: Several medical databases were searched comprehensively from inception to September 2023. Studies with available English full texts and results for bowel dysfunction following percutaneous tibial nerve stimulation (PTNS) or transcutaneous tibial nerve stimulation (TTNS) were considered. The publications that were included underwent a comprehensive assessment by two independent reviewers, and pertinent data were retrieved. The quality of the included studies was evaluated using Cochrane guidelines. Results: From a total of 200 studies, only 2 prospective interventional studies were eligible for entering this systematic review with no control arm. A total of 93 patients diagnosed with MS (44 females and 49 males) with a median age of 48.32 years were included. Both studies applied PTNS in 30-minute sessions for a maximum of 12 weeks and reported an overall improvement following PTNS in MS-associated bowel dysfunction. Conclusion: This systematic review demonstrated that PTNS can be an effective way of minimizing fecal incontinence in MS patients. However, due to the highly limited number of available publications on this issue, we cannot generalize these findings to larger populations.

Tibial nerve electrical stimulation for fecal incontinence: a systematic review and meta-analysis.

Tibial nerve stimulation (TNS) therapy is widely used to treat fecal incontinence (FI), but still, some controversy exists. This study aimed to determine whether TNS could improve FI from different evaluation angles. A systematic review and meta-analysis were conducted to provide indirect evidence of TNS treatment for FI. We searched for the original studies in PubMed, Embase, Web of Science, Ebsco Medline, Ovid Medline, and Cochrane Central Register of Controlled Trials published before November 31, 2021. The standardized mean difference was the efficacy analysis statistic, and the effect was expressed by the 95% confidence interval (CI). For the case series, we calculated the mean difference of the number of patients evaluated at baseline and last follow-up. Four randomized controlled trials (RCTs, four hundred and sixty participants) and eighteen case series (eight hundred and thirty-eight participants) were included in the study. The results of the RCTs showed that the number of weekly episodes of FI significantly reduced in the TNS group compared with the sham stimulation group. The results of the case series showed that TNS reduced the number of patients with FI per week. The Cleveland Clinic Florida FI Score significantly reduced. The post-treatment results of maximum squeeze pressure and maximum resting pressure were significantly different from baseline. This study showed that TNS to some extent reduced the number of patients with FI, reduced clinical symptoms, and improved anal physiological function. Despite the low quality of overall evidence, TNS still shows some potential as a safe treatment for FI.

Posterior tibial nerve stimulation as a neuromodulation therapy in treatment of neurogenic overactive bladder in multiple sclerosis: A prospective randomized controlled study

Backgroundone of the major annoying disorders occurring in people with multiple sclerosis is lower urinary tract disorders (LUT). Urgency is considered the main one seriously influencing the quality of life. Neurogenic detrusor over activity (DOAB) is characterized by a hyperreflexic, overactive detrusor that responds quickly to low-intensity sensory input from general visceral afferent fibers. Overactivity has been claimed to induce random, uncontrolled contractions of the detrusor muscle, leading to intravesicular pressure rise, producing urgency, frequency, and consequently incontinence AimTo demonstrate the therapeutic efficacy for posterior tibial nerve stimulation (PTNS) in neurogenic over active bladder (NOAB) in people with multiple sclerosis MethodsThe current trial is a prospective, randomized controlled study. Forty remitting relapsing males with MS with moderate NOAB symptoms were randomly assigned into two equal groups; control group (C) treated by selected therapeutic exercises program for strengthening pelvic floor muscles and an intervention group (ES) receiving an additional posterior tibial nerve electrical stimulation. Each session ranged from 45- 50 minutes, three days weekly for a month. Outcome measures were recorded before starting the treatment and after termination of the study intervention and included over active bladder symptoms score (OVBS) score, urodynamic parameters (uroflow, filling and voiding cystometry), and post voiding residual volume by abdominal ultrasound ResultsThere was a significant improvement of all voiding parameters compared to baseline and the group C except frequency of urgency incontinence. A significant decrease was detected in post-treatment mean episodes number of nighttime frequency, urgency, urgency incontinence (1.65 ± 0.93, 1.2 ± 0.52 and 1.5 ± 0.76) respectively of the ES group compared to that of group C (3.05 ± 1.09, 2.25 ± 0.71 and 2.25 ± 1.06) (P < 0.01). There was a significant decrease in median post-treatment OVBS score 3 (3-3) compared to group C median score 5 (6-4). A statistically significant improvement was observed of all urodynamic parameters (bladder capacity and compliance, Detrusor overactivity (DO), maximum flow rate and post voidal residual volume in the ES group compared to the group C ConclusionPTNS is a promising and potentially beneficial treatment option for NOAB symptoms in males with MS and superior to pelvic floor muscle training alone.

A feasibility study on the clinical use of noninvasive tibial nerve stimulation towards neurogenic bladder in spinal cord injured individuals

Abstract This research assesses the effect of tibial nerve electrical stimulation on urinary incontinence in individuals with spinal cord injury (SCI) being a prospective noncontrolled intervention study. 8 individuals with SCI were recruited from the outpatient clinic. This study demonstrates results of tibial nerve stimulation (TNS) applied to the tibial nerves for 12 weeks. Two questionnaires were applied (Neurogenic Bladder Symptom Score-NBSS and Qualiveen- SF) and presented a tendency to improve symptoms and quality of life, however, without statistical significance. With the urodynamic data: maximum cystometric capacity increased with a mean of 285.6 ml pre, to 314.8 ml post TNS (P-Value: 0.554); compliance increased from 26.38ml/cmH2O pre TNS to 29.88ml/cmH2O post TNS (PValue: 0.461); detrusor hyperactivity in the filling phase occurred in all patients in the pre TNS assessment; the maximum amplitude of the detrusor pressure in mean detrusor overactivity after TNS increased from 62.0 to 66.6 cmH2 (PValue: 0.674); urinary leakage pressure during detrusor overactivity pre TNS were mean of 54.0 and 53.2 after (PValue: 1). The implications for rehabilitation practice and the positive effects of TNS are fundamental to improving the quality of life and reducing urinary incontinence on these individuals. Clinical outcomes, i.e., improvement on urinary incontinence can be achieved within a short period of intervention.

Biofeedback pelvic floor muscle training and posterior tibial nerve electrostimulation for treatment of faecal incontinence: monotherapy versus combined therapy: a prospective randomized trial

BackgroundFaecal incontinence is a common anorectal medical trouble among adult population. The aim was to compare the efficacy of biofeedback pelvic floor muscle training versus posterior tibial nerve electrical stimulation versus combination of both of them in treatment of patients with faecal incontinence. The study included 71 randomly selected patients with faecal incontinence. Eleven patients had one or more exclusion criteria were excluded from the study. Sixty patients were included in the trial. They were randomly assigned to receive biofeedback pelvic floor muscle training (biofeedback group), posterior tibial nerve electrostimulation (posterior tibial nerve electrostimulation group) or combined therapy (combined group). Primary outcome measure was Wexner Faecal Continence scale. Secondary outcome measures were maximal squeezing anal pressure, maximal voluntary anal contraction time and patient global assessment of effect of faecal incontinence on quality of life. The outcome measures were recorded twice, before treatment and after treatment by six weeks.ResultsNo statistical significant differences were present between the three groups regarding different baseline clinical characteristics. Significant differences were present between the initial and follow-up assessment of the outcome measures within the three groups. However, there were significant differences between the three groups regarding the outcome measures within follow-up assessment. There were 14 patients (70%) showed successful outcome in the combined group versus 11 patients (55%) in the biofeedback group and 6 patients (30%) in the posterior tibial nerve electrostimulation group.ConclusionsCombination therapy of biofeedback pelvic floor muscle training and posterior tibial nerve electrostimulation in the treatment of patient with faecal incontinence is quantitatively better than biofeedback pelvic floor muscle training therapy alone and superior to posterior tibial nerve electrostimulation therapy alone, as well as biofeedback pelvic floor muscle training therapy is superior to posterior tibial nerve electrostimulation therapy. This combination could be recommended as an effective treatment for faecal incontinence. It increases the anal sphincter squeezing pressure with improvement in the patients’ quality of life.Trial registration: Pan African Clinical Trials Registry, PACTR202008862941254. Registered 24 August 2020—Retrospectively registered, https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=12291.

Central fatigue aetiology in prolonged trail running races.

What is the central question of this study? Are spinal and/or supraspinal perturbations implicated in central fatigue induced in the plantar flexor muscles following prolonged trail running races? What is the main finding and its importance? The study confirmed the presence of central fatigue following various trail running distances from 40 to 170km. The reduction in the V-wave in conjunction with the lack of change in the H-reflex suggests that a major component of this central fatigue may arise from supraspinal mechanisms in the plantar flexor muscles. Trail running races are known to induce considerable impairments in neuromuscular function of which central mechanisms are a substantial component. However, the loci of this central fatigue (i.e. supraspinal and/or spinal) is not well identified. The aim of this study was to better understand central fatigue aetiology induced in the plantar flexor muscles by various trail running distances from 40 to 170km. Eighteen runners participated in the study and neuromuscular function of their plantar flexors was tested before (PRE) and after (POST) various races during the Ultra-Trail du Mont Blanc. Neuromuscular function was evaluated with voluntary and evoked contractions using electrical tibial nerve stimulation. H-reflex and V-wave responses were also measured during submaximal and maximal voluntary contraction, respectively. Reductions in maximal voluntary contraction torque (-29%; P<0.001) and voluntary activation level (-12%; P<0.001) were observed after trail running races. The V-wave was reduced in soleus (-35%; P=0.003) and gastrocnemius medialis (-28%; P=0.031), with no changes for the H-reflex in soleus (P=0.577). The present study confirmed the presence of central fatigue following trail running exercise. The reduction in the V-wave in conjunction with the lack of change in the H-reflex suggests that a major component of this central fatigue may arise from supraspinal mechanisms.

Comparison of transcutaneous electrical tibial nerve stimulation for the treatment of overactive bladder: a multi-arm randomized controlled trial with blinded assessment

OBJECTIVE:To compare the effectiveness of tibial nerve transcutaneous electrical nerve stimulation (TENS) for an overactive bladder, considering the sites of application and frequency of attendance.METHODS:This multi-arm randomized controlled trial enrolled 137 adult women (61.0±9.0 years) with overactive bladder from a university hospital. They underwent 12 sessions of 30-min TENS application and were assigned to five groups: one leg, once a week (n=26); one leg, twice a week (n=27); two legs, once a week (n=26); two legs, twice a week (n=28); and placebo (n=30). Symptoms of overactive bladder and its impact on quality of life were evaluated before and after 6 or 12 weeks of treatment using the Overactive Bladder Questionnaire-V8 and voiding diary. ClinicalTrials.gov: NCT01912885.RESULTS:The use of one leg, once a week TENS application reduced the frequency of urgency episodes compared with the placebo (1.0±1.6 vs. 1.4±1.9; p=0.046) and frequency of incontinence episodes compared with the placebo (0.7±1.4 vs.1.4±2.2; p<0.0001). The one-leg, twice a week protocol decreased the urinary frequency compared with the two legs, once a week protocol (8.2±3.5 vs. 9.0±5.1; p=0.026) and placebo (8.2±3.5 vs. 7.9±2.7; p=0.02). Nocturia improved using the two legs, once a week protocol (1.5±1.8) when compared with the one leg, twice a week protocol (1.9±2.0) and placebo (1.7±1.6) (p=0.005 and p=0.027, respectively). Nocturia also improved using the two legs, twice a week protocol when compared with the one leg, twice a week protocol (1.3±1.2 vs.1.9±2.0; p=0.011).CONCLUSION:One-leg stimulation improved the daily urinary frequency, urgency, and incontinence, and the two-leg stimulation once and twice weekly improved nocturia.

Is the addition of vaginal electrical stimulation to transcutaneous tibial nerve electrical stimulation more effective for overactive bladder treatment? A randomized controlled trial

Introduction and objectivesOveractive bladder (OAB) is a prevalent disorder that increases with age and impairs patients’ quality of life. Guidelines recommend behavior modifications as the first-line treatment; however, physiotherapy has also been used with success, safety, and low cost. Transcutaneous tibial nerve electrical stimulation (TTNS) and vaginal electrical stimulation (VS) are being used in clinical physiotherapy practice. This study aimed to verify whether the addition of VS to TTNS is more beneficial than TTNS alone for women with OAB. Patients and methodsIn all, 106 women aged >18 years diagnosed with OAB or mixed urinary incontinence with prevalent OAB symptoms were randomly divided into 2 groups: Group 1: TTNS (n=52); Group 2: TTNS+VS (n=54). The 3 day voiding diary, pelvic floor muscle strength (Ortiz scale), King's Health Questionnaire, and Overactive Bladder Questionnaire were assessed before and after treatment. Urinary frequency was considered the primary outcome, and a reduction of ≥3micturitions/day was considered clinically relevant. Mixed linear models were used to compare the 2 groups. ResultsInitially, the groups were similar in age, body mass index, number of pregnancies, time of OAB onset, and prevalence of OAB symptoms. After treatment, a reduction in urinary frequency of 1.5 micturitions was observed in Group 2, which was not clinically relevant despite being statistically significant. ConclusionsThe addition of VS to TTNS for the treatment of OAB was not more effective than TTNS as a single therapy.

The role of tibial nerve stimulation for enhanced postoperative recovery after colorectal surgery: a double-blind, parallel-group, randomized controlled trial.

Postoperative ileus (POI) is the most common cause of prolonged hospital stay following abdominal surgery, despite an optimized enhanced recovery after surgery (ERAS) program. The aim of the study was to evaluate the role of postoperative transcutaneous electrical tibial nerve stimulation (TTNS) in the recovery of bowel function and in shortening hospital stay after colonic resection. Patients having elective laparoscopic colonic surgery within an ERAS program at our institution between June 2016 and June 2019 were enrolled and randomly assigned to a treatment protocol with TTNS or sham electrical stimulation. The primary endpoint was the time of recovery of gastrointestinal motility, measured as the first passage of stool. Secondary endpoints included: first passage of flatus, length of hospital stay, and complication rate related to the use of TTNS. One hundred and seventy patients who had right hemicolectomy (median age 71years (range 43-89years); 47.5% women) and 170 patients who had left colectomy (median age 67years range (37-92years); 41.5% women) were enrolled. The only factor significantly affected by TTNS was time to first passage of flatus after right hemicolectomy (reduced from 46 to 33h, p = 0.04). However, if only patients with low compliance to early oral nutrition (63 of 340; 18.5%) were considered, a statistically significant difference in time until first flatus (p < 0.01) and first bowel movement (p < 0.0001) and a shorter time until discharge (median 5 vs 7days) were found in both left and right colectomies groups, respectively. TTNS may have a positive effect on gastrointestinal tract motility and recovery from POI after colorectal surgery in a selected group, who has low compliance with an ERAS program, without increasing the risk of complications.

¿Es más efectivo el tratamiento combinado de electroestimulación transcutánea del nervio tibial y electroestimulación vaginal que el tratamiento en monoterapia de electroestimulación del nervio tibial para la vejiga hiperactiva? Un ensayo controlado aleatorizado

Introduction and objectivesOveractive bladder (OAB) is a prevalent disorder that increases with age and impairs patients’ quality of life. Guidelines recommend behavior modifications as the first-line treatment; however, physiotherapy has also been used with success, safety, and low cost. Transcutaneous tibial nerve electrical stimulation (TTNS) and vaginal electrical stimulation (VS) are being used in clinical physiotherapy practice. This study aimed to verify whether the addition of VS to TTNS is more beneficial than TTNS alone for women with OAB. Patients and methodsIn all, 106 women aged >18 years diagnosed with OAB or mixed urinary incontinence with prevalent OAB symptoms were randomly divided into 2 groups: Group 1: TTNS (n = 52); Group 2: TTNS + VS (n = 54). The 3 day voiding diary, pelvic floor muscle strength (Ortiz Scale), King's Health Questionnaire, and Overactive Bladder Questionnaire were assessed before and after treatment. Urinary frequency was considered the primary outcome, and a reduction of ≥ 3 micturitions/day was considered clinically relevant. Mixed linear models were used to compare the 2groups. ResultsInitially, the groups were similar in age, body mass index, number of pregnancies, time of OAB onset, and prevalence of OAB symptoms. After treatment, a reduction in urinary frequency of 1.5 micturitions was observed in Group 2, which was not clinically relevant despite being statistically significant. ConclusionsThe addition of VS to TTNS for the treatment of OAB was not more effective than TTNS as a single therapy.

Vibration-induced depression in spinal loop excitability revisited.

While it has been well described that prolonged vibration locally applied to a muscle or its tendon (up to 1h) decreases spinal loop excitability between homonymous Ia afferents and motoneurons, the involved mechanisms are not fully understood. By combining electrophysiological methods, this study aimed to provide new insights into the mechanisms involved in soleus decreased spinal excitability after prolonged local vibration. We report that prolonged vibration induces a decrease in motoneuron excitability rather than an increase in presynaptic mechanisms (as commonly hypothesized in the current literature). The present results may help to design appropriate clinical intervention and could reinforce the interest in vibration as a treatment for spastic patients who are characterized by spinal hyper-excitability responsible for spasms and long-lasting reflexes. The mechanisms that can explain the decreased spinal loop excitability in response to prolonged local vibration (LV), as assessed by the H-reflex, remain to be precisely determined. This study provides new insights into how prolonged Achilles' tendon LV (30min, 100Hz) acutely interacts with the spinal circuitry. The roles of presynaptic inhibition exerted on Ia afferents (ExperimentA, n=15), neurotransmitter release at the synapse level (ExperimentB, n=11) and motoneuron excitability (ExperimentC, n=11) were investigated in soleus. Modulation of presynaptic inhibition was assessed by conditioning the soleus H-reflex (tibial nerve electrical stimulation) with fibular nerve (D1 inhibition) and femoral nerve (heteronymous facilitation, HF) electrical stimulations. Potential vibration-induced changes in neurotransmitter depletion at the Ia afferent terminals was assessed through paired stimulations applied over the tibial nerve (HD). Intrinsic motoneuron excitability was assessed with thoracic motor evoked potentials (TMEPs) in response to electrical stimulation over the thoracic spine. Non-conditioned H-reflex was depressed by ∼60% after LV (P<0.001), while D1 and HF H-reflexes increased by ∼75% after LV (P=0.03 and 0.06, respectively). In ExperimentB, HD remained unchanged after LV (P=0.80). In ExperimentC, TMEPs were reduced by ∼13% after LV (P=0.01). Overall, presynaptic mechanisms do not seem to be involved in the depression of spinal excitability after LV. It rather seems to rely, at least in part, on a decrease in intrinsic motoneuron excitability. These results may have implications in reducing spinal hyper-excitability in spastic patients.

Effect of Paired Associative Stimulation on Motor Cortex Excitability in Rats.

Paired associative stimulation (PAS), combining transcranial magnetic stimulation (TMS) with electrical peripheral nerve stimulation (PNS) in pairs with an optimal interstimulus interval (ISI) in between, has been shown to influence the excitability of the motor cortex (MC) in humans. However, the underlying mechanisms remain unclear. This study was designed to explore an optimal protocol of PAS, which can modulate the excitability of MC in rats, and to investigate the underlying mechanisms. The resting motor thresholds (RMTs) of TMS-elicited motor evoked potentials (MEPs) recorded from the gastrocnemius muscle and the latency of P1 component of somatosensory evoked potentials (SEPs) induced by electrical tibial nerve stimulation were determined in male Sprague-Dawley rats (n=10). Sixty rats were then randomly divided into 3 groups: a PAS group (further divided into 10 subgroups at various ISIs calculated by using the latency of P1, n=5, respectively), a TMS (only) group (n=5) and a PNS (only) group (n=5). Ninety repetitions of PAS, TMS and PNS were administered to the rats in the 3 groups, respectively, at the frequency of 0.05 Hz and the intensity of TMS at 120% RMT and that of PNS at 6 mA. RMTs and motor evoked potentials' amplitude (MEPamp) were recorded before and immediately after the interventions. It was found that the MEPamp significantly decreased after PAS at ISI of 5 ms (P<0.05), while the MEPamp significantly increased after PAS at ISI of 15 ms, as compared with those before the intervention (P<0.05). However, the RMT did not change significantly after PAS at ISI of 5 ms or 15 ms (P>0.05). PAS at other ISIs as well as the sole use of TMS and PNS induced no remarkable changes in MEPamp and RMT. In conclusion, PAS can influence motor cortex excitability in rats. Neither TMS alone nor PNS alone shows significant effect.

Reduction of Postoperative Ileus by Perioperative Transcutaneous Electrical Tibial Nerve Stimulation.

Reduction of Postoperative Ileus by Perioperative Transcutaneous Electrical Tibial Nerve Stimulation.

Modulation of Hoffmann reflex excitability during action observation of walking with and without motor imagery

Action observation (AO) and motor imagery (MI) are used for motor impairment rehabilitation after neurological disorders, such as spinal cord injuries or strokes. Clinical studies have reported that rehabilitation using AO and MI is effective in restoring motor function. Our previous study showed a difference in the modulation of corticospinal excitability only during action observation (AO) of walking and AO of walking combined with motor imagery (AO + MI). However, it is unclear whether AO and AO + MI can modulate spinal reflex excitability as well as corticospinal excitability. Thus, the purpose of this study was to investigate the modulation of the Hoffmann reflex (H-reflex) during AO and AO + MI.We measured H-reflex in the soleus muscle under the following conditions: (1) control, (2) AO, and (3) AO + MI. Posterior tibial nerve electrical stimulation, which induces H-reflex, was applied at the following four walking phases: 1) mid-stance, 2) terminal-stance, 3) early-swing, and 4) terminal-swing. Our results showed that AO + MI significantly increases H-reflex over AO alone, regardless of phase and that AO significantly modulates H-reflex depending on the observed phase. These findings suggested that spinal reflex excitability can be modulated during AO and AO + MI and that neural effects are different in AO and AO + MI.

Movement-Related Somatosensory Activity Is Altered in Patients with Multiple Sclerosis.

During active movement the somatosensory cortical responses are often attenuated. This attenuation is referred to as movement-related sensory gating. It is well known that patients with multiple sclerosis (MS) have sensory processing deficits, and recent work has also suggested that these patients display impaired motor control of the ankle musculature. The primary goal of the current study was to: (1) examine the movement-related somatosensory gating in patients with MS and demographically-matched controls, and (2) identify the relationship between the sensory gating and motor control of the ankle musculature. To this end, we used magnetoencephalography brain imaging to assess the neural responses to a tibial nerve electrical stimulation that was applied at rest (passive) and during an ankle plantarflexion motor task (active condition). All participants also completed an ankle isometric motor control task that was performed outside the scanner. Our results indicated that the controls, but not patients with MS, exhibited significantly reduced somatosensory responses during the active relative to passive conditions, and that patients with MS had stronger responses compared with controls during the active condition. Additionally, control of the ankle musculature was related to the extent of movement-related sensory attenuation, with poor motor control being associated with reduced gating. Overall, these results show that patients with MS do not attenuate the somatosensory cortical activity during motor actions, and that the inability to modulate somatosensory cortical activity is partially related to the poor ankle motor control seen in these patients.

Age-related erosion of obstacle avoidance reflexes evoked with electrical stimulation of tibial nerve during walking.

In young healthy adults, characteristic obstacle avoidance reflexes have been demonstrated in response to electrical stimulation of cutaneous afferents of the foot during walking. It is unknown whether there is an age-related erosion of this obstacle avoidance reflex evoked with stimulation to the tibial nerve innervating the sole of the foot. The purpose of this study was to identify age-dependent differences in obstacle avoidance reflexes evoked with electrical stimulation of the tibial nerve at the ankle during walking in healthy young and older (70 yr and older) adults with no history of falls. Toe clearance, ankle and knee joint displacement and angular velocity, and electromyograms (EMG) of the tibialis anterior, medial gastrocnemius, biceps femoris, and vastus lateralis were measured. A significant erosion of kinematic and EMG obstacle avoidance reflexes was seen in the older adults compared with the young. Specifically, during swing phase, there was reduced toe clearance, ankle dorsiflexion, and knee flexion angular displacement in older adults compared with the young as well as changes in muscle activation. These degraded reflexes were superimposed on altered kinematics seen during unperturbed walking in the older adults including reduced toe clearance and knee flexion and increased ankle dorsiflexion compared with the young. Notably, during mid-swing the toe clearance was reduced in the older adults compared with the young by 2 cm overall, resulting from a combination of 1-cm reduced reflex response in the older adults superimposed on 1-cm less toe clearance during unperturbed walking. Together, these age-related differences could represent the prodromal phase of fall risk. NEW & NOTEWORTHY This study demonstrated age-dependent erosion of obstacle avoidance reflexes evoked with electrical stimulation of the tibial nerve at the ankle during walking. There was significant reduction in toe clearance, ankle dorsiflexion, and knee flexion reflexes as well as changes in muscle activation during swing phase in older adults with no history of falls compared with the young. These degraded reflexes, superimposed on altered kinematics seen during unperturbed walking, likely represent the prodromal phase of fall risk.