Low-level Electrical Stimulation Research Articles

Effects of Varied Stimulation Parameters on Adipose-Derived Stem Cell Response to Low-Level Electrical Fields.

Exogenous electrical fields have been explored in regenerative medicine to increase cellular expression of pro-regenerative growth factors. Adipose-derived stem cells (ASCs) are attractive for regenerative applications, specifically for neural repair. Little is known about the relationship between low-level electrical stimulation (ES) and ASC regenerative potentiation. In this work, patterns of ASC expression and secretion of growth factors (i.e., secretome) were explored across a range of ES parameters. ASCs were stimulated with low-level stimulation (20 mV/mm) at varied pulse frequencies, durations, and with alternating versus direct current. Frequency and duration had the most significant effects on growth factor expression. While a range of stimulation frequencies (1, 20, 1000 Hz) applied intermittently (1 h × 3 days) induced upregulation of general wound healing factors, neural-specific factors were only increased at 1 Hz. Moreover, the most optimal expression of neural growth factors was achieved when ASCs were exposed to 1 Hz pulses continuously for 24 h. In evaluation of secretome, apparent inconsistencies were observed across biological replications. Nonetheless, ASC secretome (from 1 Hz, 24 h ES) caused significant increase in neurite extension compared to non-stimulated control. Overall, ASCs are sensitive to ES parameters at low field strengths, notably pulse frequency and stimulation duration.

Noisy Galvanic Vestibular Stimulation Combined With a Multisensory Balance Program in Older Adults With Moderate to High Fall Risk: Protocol for a Feasibility Study for a Randomized Controlled Trial.

BackgroundReduced mobility and falls are common among older adults. Balance retraining programs are effective in reducing falls and in improving balance and mobility. Noisy galvanic vestibular stimulation is a low-level electrical stimulation used to reduce the threshold for the firing of vestibular neurons via a mechanism of stochastic resonance.ObjectiveThis study aims to determine the feasibility of using noisy galvanic vestibular stimulation to augment a balance training program for older adults at risk of falls. We hypothesize that noisy galvanic vestibular stimulation will enhance the effects of balance retraining in older adults at risk of fallsMethodsIn this 3-armed randomized controlled trial, community dwelling older adults at risk of falling will be randomly assigned to a noisy galvanic vestibular stimulation plus balance program (noisy galvanic vestibular stimulation group), sham plus balance program (sham group), or a no treatment group (control). Participants will attend the exercise group twice a week for 8 weeks with assessment of balance and gait pretreatment, posttreatment, and at 3 months postintervention. Primary outcome measures include postural sway, measured by center of pressure velocity, area and root mean square, and gait parameters such as speed, step width, step variability, and double support time. Spatial memory will also be measured using the triangle completion task and the 4 Mountains Test.ResultsRecruitment began in November 2020. Data collection and analysis are expected to be completed by December 2022.ConclusionsThis study will evaluate the feasibility of using noisy galvanic vestibular stimulation alongside balance retraining in older adults at risk of falls and will inform the design of a fully powered randomized controlled trial.Trial RegistrationNew Zealand Clinical Trials Registry (ACTRN12620001172998); https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=379944International Registered Report Identifier (IRRID)DERR1-10.2196/32085

Anti-arrhythmic and anti-heart failure effects of low-level electrical stimulation on aortic root ventricular ganglionated plexi.

It remains uncertain whether low-level electrical stimulation (LL-ES) of the ventricular ganglionated plexi (GP) improves heart function. This study investigated the anti-arrhythmic and anti-heart failure effects of LL-ES of the aortic root ventricular GP (ARVGP). Thirty dogs were divided randomly into control, drug, and LL-ES groups after performing rapid right ventricular pacing to establish a heart failure (HF) model. The inducing rate of arrhythmia; levels of bioactive factors influencing HF, including angiotensin II type I receptor (AT-1R), transforming growth factor-beta (TGF-β), matrix metalloproteinase (MMP), and phosphorylated extracellular signal-regulated kinase (p-ERK1/2); left ventricular stroke volume (LVSV), and left ventricular ejection fraction (LVEF)were measured after treatment with placebo, drugs, and LL-ES. The inducing rate of atrial arrhythmia decreased from 60% in the control group to 50% in the drug group and 10% in the LL-ES group (p=.033vs. drug group) after 1week of treatment. The ventricular effective refractory period was prolonged from 139 ± 8ms in the drug group to 166 ± 13ms in the LL-ES group (p=.001). Compared to the drug group, the expressions of AT-1R, TGF-β, and MMP proteins were down-regulated in the LL-ES group, whereas that of p-ERK1/2 was significantly increased (all p=.001). Moreover, in the LL-ES group, LVSV increased markedly from 13.16 ± 0.22 to 16.86 ± 0.27mL, relative to that in the drug group (p=.001), and LVEF increased significantly from 38.48% ± 0.53% to 48.94% ± 0.57% during the same time frame (p=.001). Short-term LL-ES of ARVGP had both anti-arrhythmic and anti-inflammatory effects and contributed to the treatment of tachycardia-induced HF and its associated arrhythmia.

Vagus nerve stimulation paired with tones for tinnitus suppression: Effects on voice and hearing.

ObjectiveIn individuals with chronic tinnitus, our interest was to determine whether daily low‐level electrical stimulation of the vagus nerve paired with tones (paired‐VNSt) for tinnitus suppression had any adverse effects on motor‐speech production and physiological acoustics of sustained vowels. Similarly, we were also interested in evaluating for changes in pure‐tone thresholds, word‐recognition performance, and minimum‐masking levels. Both voice and hearing functions were measured repeatedly over a period of 1 year.Study designLongitudinal with repeated‐measures.MethodsDigitized samples of sustained frontal, midline, and back vowels (/e/, /o/, /ah/) were analyzed with computer software to quantify the degree of jitter, shimmer, and harmonic‐to‐noise ratio contained in these waveforms. Pure‐tone thresholds, monosyllabic word‐recognition performance, and MMLs were also evaluated for VNS alterations. Linear‐regression analysis was the benchmark statistic used to document change over time in voice and hearing status from a baseline condition.ResultsMost of the regression functions for the vocal samples and audiometric variables had slope values that were not significantly different from zero. Four of the nine vocal functions showed a significant improvement over time, whereas three of the pure tone regression functions at 2‐4 kHz showed some degree of decline; all changes observed were for the left ear, all were at adjacent frequencies, and all were ipsilateral to the side of VNS. However, mean pure‐tone threshold changes did not exceed 4.29 dB from baseline and therefore, would not be considered clinically significant. In some individuals, larger threshold shifts were observed. No significant regression/slope effects were observed for word‐recognition or MMLs.ConclusionQuantitative voice analysis and assessment of audiometric variables showed minimal if any evidence of adverse effects using paired‐VNSt over a treatment period of 1 year. Therefore, we conclude that paired‐VNSt is a safe tool for tinnitus abatement in humans without significant side effects.Level of evidenceLevel IV.

Anti-arrhythmic and anti-inflammatory effect of low-level electrical stimulation of aortic root ventricular ganglionated plexi in dogs with heart failure

Anti-arrhythmic and anti-inflammatory effect of low-level electrical stimulation of aortic root ventricular ganglionated plexi in dogs with heart failure

The Effect of Low-Level Electrical Stimulation of the Aortic Root Ventricular Ganglionated Plexi on the Treatment of Heart Failure

The Effect of Low-Level Electrical Stimulation of the Aortic Root Ventricular Ganglionated Plexi on the Treatment of Heart Failure

Effect of Low-Level Electrical Stimulation of the Arotic Root Ventricular Ganglionated Plexi on Electrical and Structural Remodling in Dogs with Heart Failure

Low-level electrical stimulation (LL-ES) of aortic root ventricular ganglionated plexi (GP) was proved to be antiarrhythmic in the initiation of AF mediated by autonomic nervous system. However,it is still uncertain whether LL-ES of the ventricular GP can reverse the structural remodeling of myocardial fibrosis and atrial enlargement following heart failure by attenuating the sympathetic tone. Therefore,this review will give an general argument on this topic.

Whole-eye electrical stimulation therapy preserves visual function and structure in P23H-1 rats

Low-level electrical stimulation to the eye has been shown to be neuroprotective against retinal degeneration in both human and animal subjects, using approaches such as subretinal implants and transcorneal electrical stimulation. In this study, we investigated the benefits of whole-eye electrical stimulation (WES) in a rodent model of retinitis pigmentosa. Transgenic rats with a P23H-1 rhodopsin mutation were treated with 30 min of low-level electrical stimulation (4 μA at 5 Hz; n = 10) or sham stimulation (Sham group; n = 15), twice per week, from 4 to 24 weeks of age. Retinal and visual functions were assessed every 4 weeks using electroretinography and optokinetic tracking, respectively. At the final time point, eyes were enucleated and processed for histology. Separate cohorts were stimulated once for 30 min, and retinal tissue harvested at 1 h and 24 h post-stimulation for real-time PCR detection of growth factors and inflammatory and apoptotic markers. At all time-points after treatment, WES-treated rat eyes exhibited significantly higher spatial frequency thresholds than untreated eyes. Inner retinal function, as measured by ERG oscillatory potentials (OPs), showed significantly improved OP amplitudes at 8 and 12 weeks post-WES compared to Sham eyes. Additionally, while photoreceptor segment and nuclei thicknesses in P23H-1 rats did not change between treatment groups, WES-treated eyes had significantly greater numbers of retinal ganglion cell nuclei than Sham eyes at 20 weeks post-WES. Gene expression levels of brain-derived neurotrophic factor (BDNF), caspase 3, fibroblast growth factor 2 (FGF2), and glutamine synthetase (GS) were significantly higher at 1 h, but not 24 h after WES treatment. Our findings suggest that WES has a beneficial effect on visual function in a rat model of retinal degeneration and that post-receptoral neurons may be particularly responsive to electrical stimulation therapy.

Low-Level Electrical Stimulation of Aortic Root Ventricular Ganglionated Plexi Attenuates Autonomic Nervous System–Mediated Atrial Fibrillation

ObjectivesThis study investigated the effect of electrical stimulation of aortic root ventricular ganglionated plexi (GP) on atrial fibrillation (AF) inducibility. BackgroundThe ventricular GP are interconnected with atrial GP to govern heart function, although the effect of ventricular GP modification on control of AF remains unknown. MethodsEffective refractory periods (ERPs) of test pulmonary veins (PVs) were measured at baseline and during high-level (HL-ES) and low-level (LL-ES) electrical stimulation of the aortic root GP. The arrhythmogenic threshold of acetylcholine and isoproterenol was determined at baseline and during HL-ES and LL-ES. Moreover, AF was induced at PVs by programmed electrical stimulation after HL-ES or LL-ES. Immunohistochemistry staining was performed to examine the autonomic activity from aortic root GP to the PVs. ResultsCompared with the baseline group, HL-ES of aortic root GP significantly shortened atrial ERP (95 ± 13 ms vs. 122 ± 9 ms) and PV ERP (104 ± 11 ms vs. 131 ± 12 ms); decreased the threshold concentration of AF by both acetylcholine (1.3 ± 0.2 μmol/l vs. 3.2 ± 0.3 μmol/l) and isoproterenol (0.3 ± 0.1 μmol/l vs. 1.3 ± 0.2 μmol/l); and increased the AF-inducing rate from PVs (90% vs. 30%). In contrast, LL-ES of the GP prevented the shortening of ERP and PV ERP to 125 ± 10 ms and 133 ± 11 ms, respectively; increased threshold levels of acetylcholine and isoproterenol to 5.7 ± 0.4 μmol/l and 3.2 ± 0.3 μmol/l; and decreased the AF-inducing rate to 5%. We also found that the biotinylated dextran amine–containing varicose fibers projected directly from the aortic root GP to the left PVs. ConclusionsThese findings suggest that autonomic innervations of left PVs partly originated from aortic root ventricular GP. Moreover, LL-ES of aortic root ventricular GP suppressed AF inducibility and arose from PVs mediated by the autonomic nervous system.

Assessment of Efficiency of the Use of Transcutaneous Electrical Nerve Stimulation in Labor Pain Relief

Objective To determine the efficiency of low‐level electrical stimulation applied by a transcutaneous electrical nerve stimulation (TENS) unit on labor pain relief. Design A prospective randomized controlled trial study. Setting The study was conducted at the obstetrics and gynecology clinic of a university hospital. Sample The sample included women who volunteered and met necessary criteria for each group: 64 women in the intervention group and 60 women in the control group. Methods A demographic data collection form, visual analog scale (VAS), labor observation form, neonatal observation form, and satisfaction form on TENS application were used as data collection tools. All data were analyzed using a statistical program. Chi‐squared test was used for the descriptive data, t test was used for the quantitative data, and regression analysis was used to determine the effect of independent variables on dependent variables. Results The VAS score means were calculated as 5.49 ± 0.98 for the intervention group and 7.71 ± 0.64 for the control group. VAS mean of the intervention group were less than the control group, which was statistically significant (p < .05). The duration of labor was 6.54 ± 2.34 hours for the TENS applied group and 8.11 ± 0.27 hours for the control group, and the difference was statistically significant (p < .05). As a result, it was determined that TENS reduces VAS scores regarding labor pain, shortens duration of labor, its efficiency is independent of other variables, and it has no side effects. Conclusion/Implications for Nursing Practice The low level electrical stimulation TENS unit reduces the VAS scores relating to labor pain, shortens the period of delivery, has no adverse effects, and its efficiency is independent from other variables. With these features, TENS application may reduce negative effects of severe labor pain on the health of the mother and infant and help pregnant women have satisfactory birth experiences. To determine the efficiency of low‐level electrical stimulation applied by a transcutaneous electrical nerve stimulation (TENS) unit on labor pain relief. A prospective randomized controlled trial study. The study was conducted at the obstetrics and gynecology clinic of a university hospital. The sample included women who volunteered and met necessary criteria for each group: 64 women in the intervention group and 60 women in the control group. A demographic data collection form, visual analog scale (VAS), labor observation form, neonatal observation form, and satisfaction form on TENS application were used as data collection tools. All data were analyzed using a statistical program. Chi‐squared test was used for the descriptive data, t test was used for the quantitative data, and regression analysis was used to determine the effect of independent variables on dependent variables. The VAS score means were calculated as 5.49 ± 0.98 for the intervention group and 7.71 ± 0.64 for the control group. VAS mean of the intervention group were less than the control group, which was statistically significant (p < .05). The duration of labor was 6.54 ± 2.34 hours for the TENS applied group and 8.11 ± 0.27 hours for the control group, and the difference was statistically significant (p < .05). As a result, it was determined that TENS reduces VAS scores regarding labor pain, shortens duration of labor, its efficiency is independent of other variables, and it has no side effects. The low level electrical stimulation TENS unit reduces the VAS scores relating to labor pain, shortens the period of delivery, has no adverse effects, and its efficiency is independent from other variables. With these features, TENS application may reduce negative effects of severe labor pain on the health of the mother and infant and help pregnant women have satisfactory birth experiences.

Effects of sensory level electrical stimulation on muscle cross-sectional area, strength and metabolite production in children with cerebral palsy

Background: Threshold electrical stimulation (TES) is a method of stimulating muscle at a very low level for a long period of time. Successful use of TES has been described in children with cerebral palsy and spina bifida, however, researchers are sharply divided in their assessment of the effect of TES. The effect of long term, low level electrical stimulation on the muscles of children with cerebral palsy has not been studied as previous researchers have studied functional outcomes of use of TES.

Abstract 11392: Chronic Low-Level Transcutaneous Electrical Stimulation of the Auricular Branch of the Vagus Nerve: A New Approach to Attenuate Neural Remodeling and Reduce Ventricular Arrhythmias in a Post-Infarction Canine Model

Introduction: Left stellate ganglion (LSG) and cardiac neural remodeling, which are associated with ventricular arrhythmias (VAs) in post-infarction model, can be attenuated by low-level vagus nerve stimulation. However, whether chronic low-level transcutaneous electrical stimulation at the tragus, where the auricular branch of vagus nerve innervate, can attenuate neural remodeling both in heart and LSG and then reduce VAs is unknown. Hypothesis: We hypothesized that chronic low-level tragus stimulation (LL-TS) would attenuate cardiac and LSG nerve remodeling and then reduce inducibility of VAs in a post-infarction model. Methods: Twenty beagles after ligating coronary artery were randomly divided into normal control (NC, n=4), MI treated with LL-TS (MI-TS n=8)and MI treated with shame LL-TS (MI-NTS, n=8)groups. LL-TS was performed at 80% below the threshold, at which sinus rate or atrioventricular conduction slowing can be initially induced, for 2 hours a day for 2 months. Left stellate ganglionic nerve activity (SGNA) and left thoracic vagal nerve activity (VNA) was recorded. Slope of ventricular restitution curves (Smax) and programmed ventricular stimulation were performed to evaluate VAs. Nerve sprouting, nerve synaptic density and associated protein expression both in LSG and hearts were evaluated by immunostaining or Western blotting. Results: Two months later, the increased SGNA induced by MI was attenuated by LL-TS. However, the increased VNA was strengthened.In the MI-TS group, the number of sympathetic nerves both in peri-infarct zone and LSG were reduced, while the parasympathetic nerve fibers were increased compared to MI-NTS group. Moreover, the expression of synaptophysin, NGF in peri-infarct as well as in LSG in the MI-TS group was significantly lower than the MI-NTS group, while the level of SK2 was much higher.Chronic LL-TS also significantly decreased the Smax, LF/HF ratio and arrhythmia score of programmed ventricular stimulation induced VAs. Conclusions: These findings suggested that chronic LL-TS augmented cardiac vagal and reduced sympathetic tone, attenuated cardiac and LSG nerve remodeling, regulated nerve associated protein expression and potentially contributed to reducing vulnerability to VAs.

Abstract 11460: Chronic Intermittent Low Level Transcutaneous Electrical Stimulation of the Auricular Branch of the Vagus Nerve Improves Left Ventricular Remodeling in Conscious Dogs With Healed Myocardial Infarction

Introduction: Vagus nerve stimulation (VNS) attenuates left ventricular remodeling after myocardial infarction (MI) by improving the imbalance of autonomic nervous system. Our previous study found Low-level tragus stimulation (LL-TS) had the same antiarrhythmic effects as VNS by regulation of the autonomic nervous system. Hypothesis: Chronic intermittent LL-TS could attenuate left ventricular remodeling in conscious dogs with healed myocardial infarction. Methods: Thirty beagle dogs were randomly divided into three groups. LL-TS group (n=10) and MI group (n=10) underwent left anterior descending coronary artery and all major diagonal branches ligation to introduce MI under general anesthesia. Control group (n=10) underwent sham surgery. Auricular vagus nerve stimulation (frequency 20Hz, pulse width 1ms) with duty cycle of 5s on and 5s off was delivered to the bilateral tragus in external auditory canal with ear-clips connected to a custom-made stimulator. The voltage slowing sinus rate was used as the threshold for setting LL-TS at 80% below that. The actual voltage of stimulation was in the range of 16 to 24V that did not cause any heart rate changes. LL-TS group was given four hours of LL-TS at 7-9AM and 4-6PM on conscious dogs from the day of MI introduction to the end of 90-day follow-up, MI group and control group were given no stimulations. Results: At the end of 90-days follow-up LL-TS group significantly reduced left ventricular dilatation, improve left ventricular contractile and diastolic function, reduced mean infarct size by about 50% compared with MI group. Also LL-TS treatment alleviated cardiac fibrosis around infarction border and significantly decreased protein level of collagen I, collagen III, TGF-β1, MMP-9 in noninfarcted left ventricular free wall tissue after MI. Moreover, the plasma level of hs-CRP, NE and NT-proBNP in LL-TS group was significantly lower than MI group from the 7th day to the end of follow-up. Conclusions: Chronic intermittent low-level transcutaneous electrical stimulation of the auricular branch of the vagus nerve can attenuate left ventricular remodeling and improve cardiac function in conscious dogs with healed myocardial infarction.

2. Amygdala kindled seizures in suspend rats: A reanalysis

Background There has been a controversy concerning the motor substrate for kindled convulsions. Dr. Daniel McIntyre of Carlton University has argued that kindled motor seizures are driven from the anterior (motor) neocortex in rats, whereas our group at the University of Toronto has argued that they are driven from the brain-stem core. Neocortical convulsions in rats tend to be clonic in nature, whereas brain-stem convulsions can be either clonic or tonic. Methods Adult, male, Long–Evans rats were suspended in harnesses that allowed visualization of both fore- and hindlimbs. The development of their motor seizures was videotaped as subjects were kindled from the right basolateral amygdala. The question was whether the developing motor seizures would resemble the convulsions triggered from the neocortex or the convulsions triggered from the brain stem. Results All subjects developed motor seizures as a result of daily, low level electrical stimulation of the right amygdala. As previously reported, motor seizures did not develop incrementally, but rather evolved in a stepwise manner - as if separate motor substrates were being recruited. Early in development, motor seizures largely involved face and forelimb clonus, which resembled a “cortical” pattern. Later in kindling, motor seizures developed tonic elements, including forelimb tonic extensions, which resembled a “brain-stem” pattern. Of interest, the clonic convulsions seen early in stimulation were accompanied by stiffening of the body and hindlimbs – which did not resemble a typical tonic hindlimb extension. This stiffening – of unknown substrate – seems to correspond to the “rearing” seen in “Stage 3–5” kindled seizures. Conclusions As they develop, kindled convulsions display elements that resemble both cortical and brain-stem convulsive behavior. Future experiments might use pharmacological tools to investigate the drug response of these convulsions. Kindled convulsions, however, also contain an element of body stiffening (rearing?) which is not traditionally associated with either cortical or brain-stem convulsions.

The adrenergic regulation of proximal tubular Na+/H+ exchanger 3 in the rat

This study in the anaesthetized rat investigated how renal sympathetic nerve activity and catecholamine release influenced NHE3 abundance and activity in proximal tubular brush border membranes using both in vivo and in vitro approaches. Renal excretory function and brush border NHE3 abundance and activity were measured in rat kidneys which underwent renal denervation, renal nerve electrical stimulation and renal infusion of phenylephrine and the NHE3 inhibitor S1661. NHE3 activity and cell surface abundance were also measured in primary cultures of proximal tubular cells treated with noradrenaline and prazosin. Acute renal denervation caused a natriuresis and diuresis, which occurred with a reduction in NHE3 abundance and activity in the brush border membranes. By contrast, low-level electrical stimulation of the renal innervation causing an antinatriuresis and antidiuresis increased NHE3 activity in the brush border membranes. Intrarenal infusion of phenylephrine caused an antinatriuresis and antidiuresis, while blockade of NHE3 activity, using local infusion of the blocker S1661, caused a natriuresis and diuresis. Exposure of primary cultures of proximal tubular cells to noradrenaline increased brush border NHE3 abundance and activity which was blocked by prior exposure to prazosin, indicating it as an α1 -adrenoceptor-mediated mechanism. Together, these findings demonstrate that the renal sympathetic nerves not only have a direct action to modulate tubular sodium reabsorption via stimulation of the NHE transporter, but also have an indirect effect, whereby NHE3 abundance is increased within the brush border membrane, thereby increasing the capacity for fluid reabsorption.

Galvanic zinc–copper microparticles produce electrical stimulation that reduces the inflammatory and immune responses in skin

The human body has its own innate electrical system that regulates the body's functions via communications among organs through the well-known neural system. While the effect of low-level electrical stimulation on wound repair has been reported, few studies have examined the effect of electric potential on non-wounded, intact skin. A galvanic couple comprised of elemental zinc and copper was used to determine the effects of low-level electrical stimulation on intact skin physiology using a Dermacorder device. Zn-Cu induced the electrical potential recorded on intact skin, enhanced H(2)O(2) production and activated p38 MAPK and Hsp27 in primary keratinocytes. Treatment with Zn-Cu was also found to reduce pro-inflammatory cytokines, such as IL-1α, IL-2, NO and TNF-α in multiple cell types after stimulation with PHA or Propionibacterium acnes bacteria. The Zn-Cu complex led to a dose-dependent inhibition of TNF-α-induced NF-κB levels in keratinocytes as measured by a dual-luciferase promoter assay, and prevented p65 translocation to the nucleus observed via immunofluorescence. Suppression of NF-κB activity via crosstalk with p38 MAPK might be one of the potential pathways by which Zn-Cu exerted its inflammatory effects. Topical application of Zn-Cu successfully mitigated TPA-induced dermatitis and oxazolone-induced hypersensitivity in mice models of ear edema. Anti-inflammatory activity induced by the Zn-Cu galvanic couple appears to be mediated, at least in part, by production of low level of hydrogen peroxide since this activity is reversed by the addition of Catalase enzyme. Collectively, these results show that a galvanic couple containing Zn-Cu strongly reduces the inflammatory and immune responses in intact skin, providing evidence for the role of electric stimulation in non-wounded skin.

Balance control enhancement using sub-sensory stimulation and visual-auditory biofeedback strategies for amputee subjects

Sub-sensory electrical or mechanical stimulation can enhance the sensitivity of the human somatosensory system to improve the balance control capabilities of elderly. In addition, clinical studies suggest that visual-auditory biofeedback can improve sensory compensation for the elderly. This study hypothesizes that the static balance and gait performance of single leg quiet standing and treadmill walking could be improved for providing proprioceptive neuromuscular facilitation using sub-sensory stimulation and visual-auditory biofeedback in amputee subjects. To test this, a computerized foot pressure biofeedback sensory compensation system using sub-threshold low-level electrical stimulation combined with visual-auditory biofeedback was developed. Seven unilateral trans-tibial amputees who wore prostheses over 2 years were recruited. The subjects performed multiple single leg quiet standing trials with sub-sensory electrical stimulation applied at the quadriceps muscle during half of the trials. Static balance performance was characterized by using a Zebris motion analysis system to measure the sway distance and duration of the centre of mass on the second sacral (S2) of the subjects. In addition, multiple treadmill ambulatory trials with or without visual-auditory biofeedback was performed. Dynamic gait performance was characterized with a Zebris instrumented insole to measure the temporal responses of foot pressure sensors. Experimental results showed an improvement in three balance performance indices (Holding Time Index, HTI, Maximum Sway Distance Index, MSDI, and Average Sway Distance Index, ASDI) during single leg quiet standing by applying sub-sensory stimulation. The improvement ratio of these balance performance indices across subjects for single leg quiet standing tests resulted in 132.34% in HTI, 44.61% in MSDI, and 61.45% in ASDI. With visual-auditory biofeedback as a cue for heel contact and toe push-off condition during treadmill ambulation, the improvement of four dynamic gait performance measures (Double Support Period, DSP, Constant Time Cadence, CTC, Single Support Period, SSP, and Stance/Swing Ratio, SSR) in amputees was verified. This resulted in 7.89% in DSP (affected side), 5.09% in CTC, 16.67% in SSP (sound side), 45.30% in SSR (sound side), and 40.30% in SSR (affected side) respectively. These findings suggest that sub-threshold electrical stimulation and visual-auditory biofeedback rehabilitation strategies may be effective in compensating sensory loss and improving static balance and dynamic ambulation performance for amputees.

Static Standing Trunk Sway Assessment in Amputees – Effects of Sub-Threshold Stimulation

Sub-threshold electrical stimulation can enhance the sensitivity of the human somatosensory system to improve the balance control capability of elderly was shown in recent rehabilitation articles. The purpose of this study was to evaluate the postural sway of trans-tibial amputees when performing single leg quiet standing on firm surface. Four unilateral trans-tibial amputees who consecutively wore prosthetics over 2 years were recruited in this study. Subjects performed single leg quiet standing trails with sub-threshold electrical stimulation applied at the quadriceps muscle during the trails. Spatial co-ordinates for the determination kinematic data (sway distance) of the center of mass (COM) on second sacral (S2) were collected using an ultrasound-based Zebris CMS-HS system. The single leg quiet standing test is measure considered to assess postural steadiness in a static position by a spatial measurement. The common notion is that a better postural steadiness, i.e. less postural sway, allows for longer time single leg quiet standing. However, there is lack of evidence how postural steadiness during single leg quiet standing changes over time. In this article, we hypothesized that the static balance of single leg quiet standing could be improved for providing proprioceptive neuromuscular facilitation using sub-sensory stimulation in amputees. To test this hypothesis, a computerized sub-threshold low-level electrical stimulation device was developed and proposed for clinical study. Experimental results show that reduction in all of the postural sway indices (constant time sway length, max sway distance and average sway distance) and increase in single leg support time index during single leg quiet standing by applying sub-sensory stimulation. The single leg quiet standing test findings suggest that sub-threshold electrical stimulation rehabilitation strategies may be effective in improving static balance performance for amputees.

Nitric oxide inhibition and the impact on renal nerve-mediated antinatriuresis and antidiuresis in the anaesthetized rat.

The contribution of nitric oxide (NO) to the antinatriuresis and antidiuresis caused by low-level electrical stimulation of the renal sympathetic nerves (RNS) was investigated in rats anaesthetized with chloralose-urethane. Groups of rats, n= 6, were given i.v. infusions of vehicle, l-NAME (10 microg kg(-1) min(-1)), 1400W (20 microg kg(-1) min(-1)), or S-methyl-thiocitrulline (SMTC) (20 microg kg(-1) min(-1)) to inhibit NO synthesis non-selectively or selectively to block the inducible or neuronal NOS isoforms (iNOS and nNOS, respectively). Following baseline measurements of blood pressure (BP), renal blood flow (RBF), glomerular filtration rate (GFR), urine flow (UV) and sodium excretion (U(Na)V), RNS was performed at 15 V, 2 ms duration with a frequency between 0.5 and 1.0 Hz. RNS did not cause measurable changes in BP, RBF or GFR in any of the groups. In untreated rats, RNS decreased UV and U(Na)V by 40-50% (both P < 0.01), but these excretory responses were prevented in l-NAME-treated rats. In the presence of 1400W i.v., RNS caused reversible reductions in both UV and U(Na)V of 40-50% (both P < 0.01), while in SMTC-treated rats, RNS caused an inconsistent fall in UV, but a significant reduction (P < 0.05) in U(Na)V of 21%. These data demonstrated that the renal nerve-mediated antinatriuresis and antidiuresis was dependent on the presence of NO, generated in part by nNOS. The findings suggest that NO importantly modulates the neural control of fluid reabsorption; the control may be facilitatory at a presynaptic level but inhibitory on tubular reabsorptive processes.

A review of sacral nerve stimulation for the treatment of faecal incontinence.

Sacral nerve stimulation is an emerging surgical technique that uses chronic low-level electrical stimulation, applied to the nerves of the sacral plexus, to produce a clinically beneficial physiological effect on the lower bowel, pelvic floor and anal canal. Faecal incontinence is common, maximal conservative therapy may improve some patients but many require surgery. Results are variable and often unsatisfactory and further options are limited, the traditional end-point being the formation of a colostomy. Sacral nerve stimulation appears to be an alternative treatment that is successful, has low morbidity, is maintained in the medium term and associated with an improved quality of life. The technique has the advantage of a minimally invasive test procedure with high predictive value and the surgery is minor. The underlying mechanism of action although predominately neurological in nature remains to be determined. Precise patient selection is currently unclear however, results are superior to other techniques.