Functional Electrical Stimulation Of Muscles Research Articles

Сlinico-biomechanical foundation of necessity of rehabilitation in adult patients with hereditary limb-girdle muscular dystrophy, type I: clinical case

Modern approach to rehabilitation of patients with limb girdle muscular dystrophy of type I are discussed in this article. Authors thoroughly investigated the clinical picture of limb-girdle muscular dystrophy, pathogenesis of this disease and the main principles of its treatment. On the example of the concrete patient authors considered the clinical picture of the limb-girdle muscle dystrophy and also the biomechanical and energetic parameters of walking. Authors demonstrated, that essential disturbance of the locomotor function is seen in this patient, what is revealed in remarkable diminution of the mean walking velocity, in severe transformation of the temporal structure of walking, in reduction of amplitude of movements at some joints of the lower extremities and increase of amplitude at the other joints, in displacement of all extreme values to the right along the temporal axis, in remarkable weakening of the support and push functions of the lower extremities, in change of the form of the vertical component Rz of ground reaction force from two-peaked to the triangular, in expressed diminution of moments of muscle forces at the joints of the lower extremities. Authors also point out, that it is necessary to carry out regular courses of rehabilitation in such patients with the purpose to improve the locomotor function. Besides, it is very expedient to retrace systematically changes of the biomechanical and innervative structure of walking. On the grounds of investigation of structure of walking of patient with limb girdle muscular dystrophy authors revealed necessity of ortheses and the subsequent application of functional electrical stimulation of muscles during walking. On the basis of realization of the trial sessions authors for the first time determined the main correctional influences, necessary for these patients and also peculiarities of the amplitude and, especially, temporal programs of functional electrical stimulation of muscles in such patients. Patient herself notes greater stability during walking, possibility of walking greater distance without fatigability. The received results give foundation for the further planning of the course of rehabilitation in such patients.

BCI-FES With Multimodal Feedback for Motor Recovery Poststroke.

An increasing number of research teams are investigating the efficacy of brain-computer interface (BCI)-mediated interventions for promoting motor recovery following stroke. A growing body of evidence suggests that of the various BCI designs, most effective are those that deliver functional electrical stimulation (FES) of upper extremity (UE) muscles contingent on movement intent. More specifically, BCI-FES interventions utilize algorithms that isolate motor signals—user-generated intent-to-move neural activity recorded from cerebral cortical motor areas—to drive electrical stimulation of individual muscles or muscle synergies. BCI-FES interventions aim to recover sensorimotor function of an impaired extremity by facilitating and/or inducing long-term motor learning-related neuroplastic changes in appropriate control circuitry. We developed a non-invasive, electroencephalogram (EEG)-based BCI-FES system that delivers closed-loop neural activity-triggered electrical stimulation of targeted distal muscles while providing the user with multimodal sensory feedback. This BCI-FES system consists of three components: (1) EEG acquisition and signal processing to extract real-time volitional and task-dependent neural command signals from cerebral cortical motor areas, (2) FES of muscles of the impaired hand contingent on the motor cortical neural command signals, and (3) multimodal sensory feedback associated with performance of the behavioral task, including visual information, linked activation of somatosensory afferents through intact sensorimotor circuits, and electro-tactile stimulation of the tongue. In this report, we describe device parameters and intervention protocols of our BCI-FES system which, combined with standard physical rehabilitation approaches, has proven efficacious in treating UE motor impairment in stroke survivors, regardless of level of impairment and chronicity.

Formulation and exploration of novel, intramuscular pressure based, muscle activation strategies in a spine model

Optimization models are often devised to assess spinal stability via estimating individual muscle forces. However, neglecting muscles' fluidic behavior remains an approximation due to the role of muscle pressure in force transmission. The purpose of this study was to leverage a validated Finite Element (FE) model of the spine, inclusive of Intra-Muscular Pressure (IMP), to explore muscle activation strategies towards maintaining equilibrium spinal stability. Three conventional strategies governing minimizing muscle effort, minimizing IVD compressive forces, and maintaining stability at all costs were first investigated to explore model's validity. Thereafter, two novel IMP-based strategies were devised and explored, specifically minimizing and maximizing IMP. The model was previously shown valid in light of in vivo and in silico observations with an average discrepancy of 6%. This being the case, the conventional strategies dictated efficacy in muscular activations whilst maintaining an equilibrium stable position, as quantified in the present paper, with a difference of 9.8% from documented data. In addition, the explored novel IMP-based strategies suggested the presence of a threshold individual muscles IMP, approximately 272 mmHg for the longissimus muscle for example, beyond which muscles potentially start to share radial loads with surrounding tissues, whilst limiting the contraction of the underlying muscles. In conclusion, this study theoretically supports the possibility of activation strategies based on muscular pressure, which the developed, verified, and validated FE spine model was leveraged to investigate. The explored novel IMP-based strategies may have significance in informing clinical applications such as motion analysis and functional electrical stimulation of muscles.

Functional changes in neural networks of the brain in patients with spastic diplegia after translingual neurostimulation

Introduction. Rehabilitation of children with cerebral palsy is one of the most difficult tasks in modern neurology. One of the promising areas is the combination of physiotherapy with methods of stimulation of various parts of the nervous system, among which functional electrical stimulation of muscles and nerves (FES) is distinguished.Purpose of research. Assessment of changes in the functional connectivity of neural networks in the brain in patients with cerebral palsy before and after translingual neurostimulation using functional MRI at rest.Materials and methods. Analyzed the results of changes in the functional connectivity of neural networks in the brain in 25 patients with cerebral palsy before and after translingual neurostimulation. A clinical examination was carried out with an assessment of complaints, anamnesis and an assessment on neurological scales, followed by standard and functional MRI of the brain at rest.Summary. In children with spastic diplegia, functional changes in neural networks with a predominance of processes of strengthening intra- and interhemispheric connections (p<0,05) were revealed, which correlates with clinical changes in the form of a decrease in spasticity and an improvement in motor skills.

Structural reorganization of the white matter pathways of the brain in patients with spastic diplegia after translingual neurostimulation

Background. Spastic diplegia (Little’s disease) is the most common form of infantile cerebral palsy (ICP), leading to persistent motor and functional impairments. One promising area of rehabilitation is a combination of physical therapy with methods of stimulation of various parts of the nervous system, among which functional electrical stimulation of muscles and nerves is the most prominent.Objective. To study structural changes of cerebral white matter conduction pathways in patients with spastic diplegia after translingual neurostimulation using magnetic resonance tractography.Materials and Methods. An open single center-controlled study was conducted. A total of 18 children were examined. All patients underwent comprehensive MRI in two time points, before and after a course of translingual neurostimulation, on a tomograph with magnetic field induction 3.0 Tesla, which included a traditional protocol in 3 mutually perpendicular planes), and diffusion-weighted imaging — DWI (Diffusion-Weight Imaging).Results. All patients after neurostimulation showed clinical improvement of movement coordination and decrease of muscle tone with formation of new motor skills, improvement of limb motor function. Statistically significant decrease of spasticity index was revealed up to 17% for arms and 23% for legs, improvement of motor skills on all three scales.Conclusion. Translingual neurostimulation allows to affect all components of motor activity, as a result of which neuroplasticity processes are activated and the brain of patients with spastic diplegia becomes more receptive to motor rehabilitation aimed at restoration of motor control and formation of new motor skills.

Breath-synchronized electrical stimulation of the expiratory muscles in mechanically ventilated patients: a randomized controlled feasibility study and pooled analysis

BackgroundExpiratory muscle weakness leads to difficult ventilator weaning. Maintaining their activity with functional electrical stimulation (FES) may improve outcome. We studied feasibility of breath-synchronized expiratory population muscle FES in a mixed ICU population (“Holland study”) and pooled data with our previous work (“Australian study”) to estimate potential clinical effects in a larger group.MethodsHolland: Patients with a contractile response to FES received active or sham expiratory muscle FES (30 min, twice daily, 5 days/week until weaned). Main endpoints were feasibility (e.g., patient recruitment, treatment compliance, stimulation intensity) and safety. Pooled: Data on respiratory muscle thickness and ventilation duration from the Holland and Australian studies were combined (N = 40) in order to estimate potential effect size. Plasma cytokines (day 0, 3) were analyzed to study the effects of FES on systemic inflammation.ResultsHolland: A total of 272 sessions were performed (active/sham: 169/103) in 20 patients (N = active/sham: 10/10) with a total treatment compliance rate of 91.1%. No FES-related serious adverse events were reported. Pooled: On day 3, there was a between-group difference (N = active/sham: 7/12) in total abdominal expiratory muscle thickness favoring the active group [treatment difference (95% confidence interval); 2.25 (0.34, 4.16) mm, P = 0.02] but not on day 5. Plasma cytokine levels indicated that early FES did not induce systemic inflammation. Using a survival analysis approach for the total study population, median ventilation duration and ICU length of stay were 10 versus 52 (P = 0.07), and 12 versus 54 (P = 0.03) days for the active versus sham group. Median ventilation duration of patients that were successfully extubated was 8.5 [5.6–12.2] versus 10.5 [5.3–25.6] days (P = 0.60) for the active (N = 16) versus sham (N = 10) group, and median ICU length of stay was 10.5 [8.0–14.5] versus 14.0 [9.0–19.5] days (P = 0.36) for those active (N = 16) versus sham (N = 8) patients that were extubated and discharged alive from the ICU. During ICU stay, 3/20 patients died in the active group versus 8/20 in the sham group (P = 0.16).ConclusionExpiratory muscle FES is feasible in selected ICU patients and might be a promising technique within a respiratory muscle-protective ventilation strategy. The next step is to study the effects on weaning and ventilator liberation outcome.Trial registration: ClinicalTrials.gov, ID NCT03453944. Registered 05 March 2018—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03453944.

Decoding unconstrained arm movements in primates using high-density electrocorticography signals for brain-machine interface use

Motor deficit is among the most debilitating aspects of injury to the central nervous system. Despite ongoing progress in brain-machine interface (BMI) development and in the functional electrical stimulation of muscles and nerves, little is understood about how neural signals in the brain may be used to potentially control movement in one’s own unconstrained paralyzed limb. We recorded from high-density electrocorticography (ECoG) electrode arrays in the ventral premotor cortex (PMv) of a rhesus macaque and used real-time motion tracking techniques to correlate spatial-temporal changes in neural activity with arm movements made towards objects in three-dimensional space at millisecond precision. We found that neural activity from a small number of electrodes within the PMv can be used to accurately predict reach-return movement onset and directionality. Also, whereas higher gamma frequency field activity was more predictive about movement direction during performance, mid-band (beta and low gamma) activity was more predictive of movement prior to onset. We speculate these dual spatiotemporal signals may be used to optimize both planning and execution of movement during natural reaching, with prospective relevance to the future development of neural prosthetics aimed at restoring motor control over one’s own paralyzed limb.

A Control Scheme That Uses Dynamic Postural Synergies to Coordinate a Hybrid Walking Neuroprosthesis: Theory and Experiments.

A hybrid walking neuroprosthesis that combines functional electrical stimulation (FES) with a powered lower limb exoskeleton can be used to restore walking in persons with paraplegia. It provides therapeutic benefits of FES and torque reliability of the powered exoskeleton. Moreover, by harnessing metabolic power of muscles via FES, the hybrid combination has a potential to lower power consumption and reduce actuator size in the powered exoskeleton. Its control design, however, must overcome the challenges of actuator redundancy due to the combined use of FES and electric motor. Further, dynamic disturbances such as electromechanical delay (EMD) and muscle fatigue must be considered during the control design process. This ensures stability and control performance despite disparate dynamics of FES and electric motor. In this paper, a general framework to coordinate FES of multiple gait-governing muscles with electric motors is presented. A muscle synergy-inspired control framework is used to derive the controller and is motivated mainly to address the actuator redundancy issue. Dynamic postural synergies between FES of the muscles and the electric motors were artificially generated through optimizations and result in key dynamic postures when activated. These synergies were used in the feedforward path of the control system. A dynamic surface control technique, modified with a delay compensation term, is used as the feedback controller to address model uncertainty, the cascaded muscle activation dynamics, and EMD. To address muscle fatigue, the stimulation levels in the feedforward path were gradually increased based on a model-based fatigue estimate. A Lyapunov-based stability approach was used to derive the controller and guarantee its stability. The synergy-based controller was demonstrated experimentally on an able-bodied subject and person with an incomplete spinal cord injury.

Comparison of Muscle Functional Electrical Stimulation to Conventional Bicycle Exercise on Endothelium and Functional Status Indices in Patients With Heart Failure

The aim of this prospective, open-label, cohort study was to compare the effect of muscle functional electrical stimulation (FES) on endothelial function to that of conventional bicycle training. Eligible patients were those with New York Heart Association class II or III heart failure symptoms and ejection fractions ≤ 0.35. Two physical conditioning programs were delivered: FES of the muscles of the lower limbs and bicycle training, each lasting for 6 weeks, with a 6-week washout period between them. Brachial artery flow-mediated dilation (FMD) and other parameters were assessed before and after FES and the bicycle training program. FES resulted in a significant improvement in FMD, which increased from 5.9 ± 0.5% to 7.7 ± 0.5% (95% confidence interval for the difference 1.5% to 2.3%, p < 0.001). Bicycle training also resulted in a substantial improvement of endothelial function. FMD increased from 6.2 ± 0.4% to 9.2 ± 0.4% (95% confidence interval for the difference 2.5% to 3.5%, p < 0.001). FES was associated with a 41% relative increase in FMD, compared to 57% with bicycle exercise (95% confidence interval for the difference between the relative changes 1.2% to 30.5%, p = 0.034). This resulted in attaining a significantly higher FMD value after bicycle training compared to FES (9.2 ± 0.4% vs 7.7 ± 0.5%, p < 0.001). In conclusion, the effect of muscle FES in patients with heart failure on endothelial function, although not equivalent to that of conventional exercise, is substantial. Muscle FES protocols may prove very useful in the treatment of patients with heart failure who cannot or will not adhere to conventional exercise programs.

Novel Patterns of Functional Electrical Stimulation Have an Immediate Effect on Dorsiflexor Muscle Function During Gait for People Poststroke

Foot drop is a common gait impairment after stroke. Functional electrical stimulation (FES) of the ankle dorsiflexor muscles during the swing phase of gait can help correct foot drop. Compared with constant-frequency trains (CFTs), which typically are used during FES, novel stimulation patterns called variable-frequency trains (VFTs) have been shown to enhance isometric and nonisometric muscle performance. However, VFTs have never been used for FES during gait. The purpose of this study was to compare knee and ankle kinematics during the swing phase of gait when FES was delivered to the ankle dorsiflexor muscles using VFTs versus CFTs. A repeated-measures design was used in this study. Thirteen individuals with hemiparesis following stroke (9 men, 4 women; age=46-72 years) participated in the study. Participants completed 20- to 40-second bouts of walking at their self-selected walking speeds. Three walking conditions were compared: walking without FES, walking with dorsiflexor muscle FES using CFTs, and walking with dorsiflexor FES using VFTs. Functional electrical stimulation using both CFTs and VFTs improved ankle dorsiflexion angles during the swing phase of gait compared with walking without FES (X+/-SE=-2.9 degrees +/- 1.2 degrees). Greater ankle dorsiflexion in the swing phase was generated during walking with FES using VFTs (X+/-SE=2.1 degrees +/- 1.5 degrees) versus CFTs (X+/-SE=0.3+/-1.3 degrees). Surprisingly, dorsiflexor FES resulted in reduced knee flexion during the swing phase and reduced ankle plantar flexion at toe-off. The findings suggest that novel FES systems capable of delivering VFTs during gait can produce enhanced correction of foot drop compared with traditional FES systems that deliver CFTs. The results also suggest that the timing of delivery of FES during gait is critical and merits further investigation.

Functional Electrostimulation of Muscles as a Method for Restoring Motor Functions

The main functions of a method of functional electrical stimulation of muscles (FES) are described: diagnostic, prognostic, and therapeutic. The main indication for using the FES method is a deficiency of muscle function, which may be organic (due to lesions to neuromuscular structures) or functional (associated with relaxation of the muscular apparatus). The five most significant functions of the FES method were established: 1) identification of correctable movements and stimulable muscles; 2) identification of the amplitude and time program for stimulation; 3) stimulation regimes for pathological gaits; 4) stimulation parameters; 5) positioning of skin electrodes on the human body. Using the example of two severe central nervous system pathologies (spinal cord lesions in the lumbosacral area and hemiparesis of cerebral origin), the positive effects of FES on the process of motor rehabilitation of this category of patients were demonstrated.

Neural prosthetic devices for quadriplegia.

Research into the use of neural prosthetic devices to treat paralysing disorders is expanding rapidly. Functional electrical stimulation of muscles is now used to activate electrically paralysed muscles to restore movements such as the hand-grasp. Sensory feedback signals recorded from peripheral nerves are used to improve the control of functional electrical stimulation systems. Functional electrical stimulation may also be used to stimulate neural circuits in the spinal cord. Electrical recordings from the brain will soon improve patients' control of neural prostheses. Non-invasive electroencephalographic recordings can currently be used to move a cursor across a computer screen. The restoration of near-to-normal limb movement control will, however, require recordings from large numbers of neurons within the brain. Preliminary feasibility has been demonstrated in experimental animals.

The bionic glove: An electrical stimulator garment that provides controlled grasp and hand opening in quadriplegia

Objective: This report describes the operation of the Bionic Glove, a new functional electrical stimulation (FES) device designed to improve the function of the paralyzed hand after spinal cord injury (SCI) or stroke. Design: Signals from a sensor in the glove detecting voluntary wrist movement are used to control FES of muscles either to produce hand-grasp or to open the hand. When the glove is donned, conductive areas on its inside surface automatically make contact with self-adhesive electrodes on the skin. Setting and Patients: This report concerns nine people with SCI who have used the device in their daily lives for up to a year or more. Measurements were made at clinics in Edmonton, Miami, and Chicago as part of a multicenter clinical trial. Outcome Measures and Results: The mean peak force of tenodesis grasp in the nine subjects increased from 2.6N (passive) to 11.3N (glove active). Active force was significantly greater than passive grasp force even when muscles were fatigued after repetitive grasp-release cycles. Most manual tasks improved significantly with the use of the glove, as judged by the number of tasks completed in a minute or the subjects' qualitative ratings of task difficulty. Conclusion: The Bionic Glove can provide significant improvement of hand function in people with C6-C7 SCI.

Functional Electrical Stimulation to Enhance Cough in Quadriplegia

Respiratory problems are a major cause of death in the acute and chronic phases of cervical spinal cord injury (CSCI); CSCI paralyzes the intercostal and abdominal muscles, reducing ability to cough and clear secretions. Impaired cough due to neuromuscular disorders can be assessed with the maximum expiratory pressure (MEP). This study consists of two experiments with CSCI patients. In the first, MEP measurements were recorded with the following maneuvers performed: (1) spontaneous cough attempts, (2) manually assisted cough, and (3) cough attempts with functional electrical stimulation (FES) applied to the abdominal wall. In the second, spontaneous cough attempts and cough attempts with a portable FES unit were recorded. These CSCI patients were found to have a greatly reduced MEP when they coughed spontaneously. Either FES-assisted or manually assisted coughing increased the MEP in all patients studied. By increasing the MEP, abdominal muscle FES could enhance cough in quadriplegics.

Properties of implanted electrodes for functional electrical stimulation

Implanted wire electrodes are increasingly being used for the functional electrical stimulation of muscles in partially paralysed patients, yet many of their basic characteristics are poorly understood. In this study we investigated the selectivity, recruitment characteristics and range of control of several types of electrode in triceps surae and plantaris muscles of anaesthetized cats. We found that nerve cuffs are more efficient and selective (i.e., cause less stimulus spread to surrounding muscles) than intramuscular electrodes. Bipolar intramuscular stimulation was more efficient and selective than monopolar stimulation, but only if the nerve entry point was between the electrodes. Monopolar electrodes are efficient and selective if located close to the nerve entry point, but their performance declines with distance from it. Nonetheless, for a variety of reasons monopolar stimulation provides the best compromise in many current applications. Short duration pulses offer the best efficiency (least charge per pulse to elicit force) but high peak currents, increasing the risk of electrode corrosion and tissue damage. Electrode size has little effect on recruitment and should therefore be maximised because this minimises current density.

Experimental and Theoretical Investigations on the Control of Limbs by the Functional Electrical Stimulation of Muscles

Problems occuring during the development of control systems within orthoses for paralyzed patients are analysed. Experimental results obtained from a simple closed-loop position control system showed that more sophisticated control stratenies are necessary to remove the deficiencies of actual control systems.With regard to the implication of appropriate control strategies a model for the “electrically stimulated musc1es-limb-load” system is derived. An adaptive control strategy for the Functional Electrical Stimulation is then described and, in view of the implementation on a digital computer, a feasible performance of this strategy is presented. The effects of different modulation techniques on the feasibility of control systems were also investigated. Pulse frequency modulation systems are found more robust than pulse amplitude modulation systems.

Variability of electrically evoked muscle contractions with special regard to closed-loop controlled orthosis

One of the essential deficiencies of functional electrical stimulation (FES) as a method of rehabilitation of hemiplegic patients is the great variability of responses. This paper treats quantitatively the variability of isometric responses. The parameters chosen for the evaluation of variability were the dynamics of isometric moment and the static value of the moment during maintained stimulation. Experiments were performed to evaluate both surface and implanted stimulation, as both of these methods have reached the stage of clinical application. It was established that the variability is quite large, relative dispersion being ν≐0.35. Using a closed-loop controller of FES of muscles it was shown that such an actuator is too variable to be used as an efficient orthosis. No significant difference was found between surface and implanted FES. The comparison of data obtained without electrode shifting and with readjustment of the electrodes to the same premarked position has convinced us that one of the main causes for the variability is the unpredictable displacement of different tissues between the electrodes and the stimulated nerve. The influence of reflex action and supraspinal centers was studied on a patient with compression of the peroneal nerve. It was found that this influence is strongly subjective. In some hemiplegics this influence was detectable, though on the average less important than the technological-anatomical properties of the contact between the electrodes and the nerve. Better reproducibility is expected with the introduction of improved electrode technology.