Posts Tagged Functional electrical stimulation (FES)
[Abstract] sEMG Bias-driven Functional Electrical Stimulation System for Upper Limb Stroke Rehabilitation
[ARTICLE] Brain-actuated functional electrical stimulation elicits lasting arm motor recovery after stroke – Full Text
Brain-computer interfaces (BCI) are used in stroke rehabilitation to translate brain signals into intended movements of the paralyzed limb. However, the efficacy and mechanisms of BCI-based therapies remain unclear. Here we show that BCI coupled to functional electrical stimulation (FES) elicits significant, clinically relevant, and lasting motor recovery in chronic stroke survivors more effectively than sham FES. Such recovery is associated to quantitative signatures of functional neuroplasticity. BCI patients exhibit a significant functional recovery after the intervention, which remains 6–12 months after the end of therapy. Electroencephalography analysis pinpoints significant differences in favor of the BCI group, mainly consisting in an increase in functional connectivity between motor areas in the affected hemisphere. This increase is significantly correlated with functional improvement. Results illustrate how a BCI–FES therapy can drive significant functional recovery and purposeful plasticity thanks to contingent activation of body natural efferent and afferent pathways.
Despite considerable efforts over the last decades, the quest for novel treatments for arm functional recovery after stroke remains a priority1. Synergistic efforts in neural engineering and restoration medicine are demonstrating how neuroprosthetic approaches can control devices and ultimately restore body function2,3,4,5,6,7. In particular, non-invasive brain-computer interfaces (BCI) are reaching their technological maturity8,9 and translate neural activity into meaningful outputs that might drive activity-dependent neuroplasticity and functional motor recovery10,11,12. BCI implies learning to modify the neuronal activity through progressive practice with contingent feedback and reward —sharing its neurobiological basis with rehabilitation13.
Most attempts to use non-invasive BCI systems for upper limb rehabilitation after stroke have coupled them with other interventions, although not all trials reported clinical benefits. The majority of these studies are case reports of patients who operated a BCI to control either rehabilitation robots14,15,16,17,18,19 or functional electrical stimulation (FES)20,21,22,23. A few works have described changes in functional magnetic resonance imaging (fMRI) that correlate with motor improvements17,18,22.
Recent controlled trials have shown the potential benefit of BCI-based therapies24,25,26,27. Pichiorri et al.26recruited 28 subacute patients and studied the efficacy of motor imagery with or without BCI support via visual feedback, reporting a significant and clinically relevant functional recovery for the BCI group. As a step forward in the design of multimodal interventions, BCI-aided robotic therapies yielded significantly greater motor gains than robotic therapies alone24,25,27. In the first study, involving 30 chronic patients24, only the BCI group exhibited a functional improvement. In the second study, involving 14 subacute and chronic patients, both groups improved, probably reflecting the larger variance in subacute patients’ recovery and a milder disability25. The last study27 showed that in a mixed population of 74 subacute and chronic patients, the percentage of patients who achieved minimally clinical important difference in upper limb functionality was higher in the BCI group. The effect in favor of the BCI group was only evident in the sub-population of chronic patients. Moreover, the conclusions of this study are limited due to differences between experimental and control groups prior to the intervention, such as number of patients and FMA-UE scores, which were always in favor of the BCI group.
In spite of promising results achieved so far, BCI-based stroke rehabilitation is still a young field where different works report variable clinical outcomes. Furthermore, the efficacy and mechanisms of BCI-based therapies remain largely unclear. We hypothesize that, for BCI to boost beneficial functional activity-dependent plasticity able to attain clinically important outcomes, the basic premise is contingency between suitable motor-related cortical activity and rich afferent feedback. Our approach is designed to deliver associated contingent feedback that is not only functionally meaningful (e.g., via virtual reality or passive movement of the paretic limb by a robot), but also tailored to reorganize the targeted neural circuits by providing rich sensory inputs via the natural afferent pathways28, so as to activate all spare components of the central nervous system involved in motor control. FES fulfills these two properties of feedback contingent on appropriate patterns of neural activity; it elicits functional movements and conveys proprioceptive and somatosensory information, in particular via massive recruitment of Golgi tendon organs and muscle spindle feedback circuits. Moreover, several studies suggest that FES has an impact on cortical excitability29,30.
To test our hypothesis, this study assessed whether BCI-actuated FES therapy targeting the extension of the affected hand (BCI–FES) could yield stronger and clinically relevant functional recovery than sham-FES therapy for chronic stroke patients with a moderate-to-severe disability, and whether signatures of functional neuroplasticity would be associated with motor improvement. Whenever the BCI decoded a hand-extension attempt, it activated FES of the extensor digitorum communis muscle that elicited a full extension of the wrist and fingers. Patients in the sham-FES group wore identical hardware and received identical instructions as BCI–FES patients, but FES was delivered randomly and not driven by neural activity.
As hypothesized, our results confirm that only the BCI group exhibit a significant functional recovery after the intervention, which is retained 6–12 months after the end of therapy. Besides the main clinical findings, we have also attempted to shed light on possible mechanisms underlying the proposed intervention. Specifically, electroencephalography (EEG) imaging pinpoint significant differences in favor of the BCI group, mainly an increase in functional connectivity between motor areas in the affected hemisphere. This increase is significantly correlated with functional improvement. Furthermore, analysis of the therapeutic sessions substantiates that contingency between motor-related brain activity and FES occurs only in the BCI group and contingency-based metrics correlate with the functional improvement and increase in functional connectivity, suggesting that our BCI intervention might have promoted activity-dependent plasticity.[…]
Findings Suggest Potential for Brain Implants to Treat Stroke Patients
UC San Francisco scientists have improved mobility in rats that had experienced debilitating strokes by using electrical stimulation to restore a distinctive pattern of brain cell activity associated with efficient movement. The researchers say they plan to use the new findings to help develop brain implants that might one day restore motor function in human stroke patients.
After a stroke, roughly one-third of patients recover fully, one-third have significant lingering movement problems, and one-third remain virtually paralyzed, said senior author Karunesh Ganguly, MD, PhD, associate professor of neurology and a member of the UCSF Weill Institute for Neurosciences. Even patients who experience partial recovery often continue to struggle with “goal-directed” movements of the arms and hands, such as reaching and manipulating objects, which can be crucial in the workplace and in daily living.
“Our main impetus was to understand how we can develop implantable neurotechnology to help stroke patients,” said Ganguly, who conducts research at the San Francisco VA Health Care System. “There’s an enormous field growing around the idea of neural implants that can help neural circuits recover and improve function. We were interested in trying to understand the circuit properties of an injured brain relative to a healthy brain and to use this information to tailor neural implants to improve motor function after stroke.”
Over the past 20 years, neuroscientists have presented evidence that coordinated patterns of neural activity known as oscillations are important for efficient brain function. More recently, low-frequency oscillations (LFOs)—which were first identified in studies of sleep—have been specifically found to help organize the firing of neurons in the brain’s primary motor cortex. The motor cortex controls voluntary movement, and LFOs chunking the cells’ activity together to ensure that goal-directed movements are smooth and efficient.
In the new study, published in the June 18, 2018 issue of Nature Medicine, the researchers first measured neural activity in rats while the animals reached out to grab a small food pellet, a task designed to emulate human goal-directed movements. They detected LFOs immediately before and during the action, which inspired the researchers to investigate how these activity patterns might change after stroke and during recovery.
To explore these questions, they caused a stroke in the rats that impaired the animals’ movement ability, and found that LFOs diminished. In rats that were able to recover, gradually making faster and more precise movements, the LFOs also returned. There was a strong correlation between recovery of function and the reemergence of LFOs: animals that fully recovered had stronger low-frequency activity than those that partially recovered, and those that didn’t recover had virtually no low-frequency activity at all.
To try to boost recovery, the researchers used electrodes to both record activity and to deliver a mild electrical current to the rats’ brains, stimulating the area immediately surrounding the center of the stroke damage. This stimulation consistently enhanced LFOs in the damaged area and appeared to improve motor function: when the researchers delivered a burst of electricity right before a rat made a movement, the rat was up to 60 percent more accurate at reaching and grasping for a food pellet.
“Interestingly, we observed this augmentation of LFOs only on the trials where stimulation was applied,” said Tanuj Gulati, PhD, a postdoctoral researcher in the Ganguly lab who is co-first author of the study, along with Dhakshin Ramanathan, MD, PhD, now assistant professor of psychiatry at UC San Diego, and Ling Guo, a neuroscience graduate student at UCSF.
“We are not creating a new frequency, we are amplifying the existing frequency,” added Ganguly. “By amplifying the weak low-frequency oscillations, we are able to help organize the task-related neural activity. When we delivered the electrical current in step with their intended actions, motor control actually got better.”
The researchers wanted to know whether their findings might also apply to humans, so they analyzed recordings made from the surface of the brain of an epilepsy patient who had suffered a stroke that had impaired the patient’s arm and hand movements. The recordings revealed significantly fewer LFOs than recordings made in two epilepsy patients who hadn’t had a stroke. These findings suggest that, just like in rats, the stroke had caused a loss of low-frequency activity that impaired the patient’s movement.
Physical therapy is the only treatment currently available to aid stroke patients in their recovery. It can help people who are able to recover neurologically get back to being fully functional more quickly, but not those whose stroke damage is too extensive. Ganguly hopes that electrical brain stimulation can offer a much-needed alternative for these latter patients, helping their brain circuits to gain better control of motor neurons that are still functional. Electrical brain stimulation is already widely used to help patients with Parkinson’s disease and epilepsy, and Ganguly believes stroke patients may be the next to benefit.
Other UCSF contributors to the work included Gray Davidson; April Hishinuma; Seok-Joon Won, PhD, associate adjunct professor of neurology; Edward Chang, MD, professor of neurosurgery and William K. Bowes Jr. Biomedical Investigator; and Raymond Swanson, MD, professor of neurology. They were joined by Robert T. Knight, MD, professor of psychology and neuroscience at UC Berkeley.
The research was supported in part by funding from the National Institute of Neurological Disorders and Stroke; the National Institute of Mental Health; the Agency for Science, Technology, and Research (A*STAR), in Singapore; the U.S. Department of Veterans Affairs, and the Burroughs Wellcome Fund.
Published on Jan 25, 2018
Video from http://www.medfaxxinc.com explains what is muscle stimulator,correctly a Functional Electrical Stimulator(FES),is for rehab.following stroke,to retard disuse atrophy,reduce swelling&edema&help patients regain function. TNS is not a MS unit but a pain machine. Some FES units can be functional restoration machines.
[ARTICLE] The immediate effect of FES and TENS on gait parameters in patients after stroke – Full Text PDF
[Purpose] This study was conducted to compare the immediate effects of different electrotherapies on the gait parameters for stroke patients.
[Subjects and Methods] Thirty patients with stroke were randomly assigned either to the functional electrical stimulation group or the transcutaneous electrical nerve stimulation group, with 15 patients in each group. Each electrotherapy was performed for 30 minutes simultaneously with the therapeutic exercise, and the changes in the spatial and temporal parameters of gait were measured.
[Results] After the intervention, a significant, immediate improvement in cadence and speed was observed only in the functional electrical stimulation group.
[Conclusion] Based on this study, functional electrical stimulation that stimulates motor nerves of the dorsiflexor muscles on the paretic side is recommended to achieve immediate improvement in the gait ability of stroke patients.[…]
Available from: https://www.researchgate.net/publication/321478935_EMG_based_FES_for_post-stroke_rehabilitation [accessed Dec 09 2017].
[ARTICLE] Arm rehabilitation in post stroke subjects: A randomized controlled trial on the efficacy of myoelectrically driven FES applied in a task-oriented approach – Full Text
Motor recovery of persons after stroke may be enhanced by a novel approach where residual muscle activity is facilitated by patient-controlled electrical muscle activation. Myoelectric activity from hemiparetic muscles is then used for continuous control of functional electrical stimulation (MeCFES) of same or synergic muscles to promote restoration of movements during task-oriented therapy (TOT). Use of MeCFES during TOT may help to obtain a larger functional and neurological recovery than otherwise possible.
Eighty two acute and chronic stroke victims were recruited through the collaborating facilities and after signing an informed consent were randomized to receive either the experimental (MeCFES assisted TOT (M-TOT) or conventional rehabilitation care including TOT (C-TOT). Both groups received 45 minutes of rehabilitation over 25 sessions. Outcomes were Action Research Arm Test (ARAT), Upper Extremity Fugl-Meyer Assessment (FMA-UE) scores and Disability of the Arm Shoulder and Hand questionnaire.
Sixty eight subjects completed the protocol (Mean age 66.2, range 36.5–88.7, onset months 12.7, range 0.8–19.1) of which 45 were seen at follow up 5 weeks later. There were significant improvements in both groups on ARAT (median improvement: MeCFES TOT group 3.0; C-TOT group 2.0) and FMA-UE (median improvement: M-TOT 4.5; C-TOT 3.5). Considering subacute subjects (time since stroke < 6 months), there was a trend for a larger proportion of improved patients in the M-TOT group following rehabilitation (57.9%) than in the C-TOT group (33.2%) (difference in proportion improved 24.7%; 95% CI -4.0; 48.6), though the study did not meet the planned sample size.
This is the first large multicentre RCT to compare MeCFES assisted TOT with conventional care TOT for the upper extremity. No adverse events or negative outcomes were encountered, thus we conclude that MeCFES can be a safe adjunct to rehabilitation that could promote recovery of upper limb function in persons after stroke, particularly when applied in the subacute phase.
Stroke is the leading cause of disability in adults in the world and can result in highly complex clinical situations. The insult often involves the sensory-motor system leading to hemiparesis and impairment of the upper limb in over 50% of survivors [1,2]. Although some structural recovery is possible, especially in the first months after stroke, only a small percentage of persons recover pre-morbid movement patterns and functionality .
Limitations in reaching and grasping have an important role in determining the level of independence of the person in their daily activities and the subsequent impact on their quality of life. Tailored goal oriented rehabilitation is therefore an essential factor in reducing impairment and augmenting functionality of a hemiplegic arm. A plurality of interventions may help the subject to restore participation and adapt to the new clinical status including task oriented therapy (TOT) that has been shown to be effective for motor recovery [4,5], as well as constraint induced movement therapy (CIMT) , biofeedback and robot assisted therapy [7–9]. Moreover, electrostimulation has been applied to improve muscle recruitment and aid motor recovery. Since resources and time in rehabilitation are limited it is important to identify and employ effective interventions .
The inability to use the arm in an efficient way may lead to non use of the arm and hand that can lead to changes also at the neural level . It is therefore essential that arm use is facilitated in meaningful activities. Approaches that assist the person during purposeful voluntarily activated movement could be important for inducing neuroplasticity and increasing function. Neuromuscular electrical stimulation (NMES) has been employed in rehabilitation of stroke patients either to generate muscle contraction or be a support during movements; however, with inconsistent results [11–20]. A prerequisite for neuroplasticity through training is the volitional intent and attention of the person and it therefore follows that the user should participate consciously in the rehabilitative intervention [21,22].
Through the use of EMG it is technically possible to register the myoelectric activity from voluntary contraction of a muscle while its motor nerve is being stimulated by electrical impulses . MeCFES is a method where the FES is directly controlled by volitional EMG activity. In contrast to EMG triggered FES, the controlling muscle is continuously controlling the stimulation intensity. Thus the resulting movement and intrinsic multisensory activation is synchronized with the active attention and intention of the subject and the muscle contraction can be gradually modulated by the subject himself facilitating motor learning and recovery of function. This has been demonstrated to be possible in spinal cord injured subjects [24,25] and a pilot study has shown that when the controlling and stimulated muscles are homologous or they are synergistic it may lead to a marked increase in motor function of the hemiparetic forearm of selected stroke patients . Motor learning principles required for CNS-activity-dependent plasticity, in fact, include task-oriented movements, muscle activation driving practice of movement, focused attention, repetition of desired movements, and training specificity [21,22,27]. The use of MeCFES during active challenging goal oriented movements should help the patient and the therapist overcome the effect of learned non use by turning attempts to move the arm into successful movements.
We hypothesize that applying MeCFES in a task oriented paradigm to assist normal arm movements during rehabilitation of the upper limb in persons with stroke will improve the movement quality and success and thus induce recovery at the body functions level (impairment) and the activity level (disability) of the International Classification of Function, Disability and Health (ICF)  superior to that induced by usual care task-oriented rehabilitation.[…]
[Abstract] Effectiveness of Functional Electrical Stimulation (FES) versus Conventional Electrical Stimulation in Gait Rehabilitation of Patients with Stroke.
PLACE AND DURATION OF STUDY: Armed Forces Institute of Rehabilitation Medicine, Rawalpindi, from July to December 2016.
METHODOLOGY: Subjects with foot drop due to stroke were allotted randomly into 1 of 2 groups receiving standard rehabilitation with Functional Electrical Stimulation (FES) or Electrical Muscle Stimulation (EMS). FES was applied on tibialis anterior 30 minutes/day, five days/week for six weeks. EMS was also applied on the tibialis anterior five days/week for six weeks. Outcome measures included Fugl-Meyer Assessment Scale, Modified Ashworth Scale, Berg Balance Scale (BBS), Time Up and Go Test (TUG) and Gait Dynamic Index (GDI). They were recorded at baseline, after 3 and 6 weeks. Pre- and post-treatment scores were analyzed between two groups on SPSS-20.
RESULTS: After six weeks of intervention, significant improvement was recorded in Fugl-Meyer Assessment score (p<0.001), modified Ashworth Scale score (p=0.027), Berg Balance Scale score (p<0.001), Time Up and Go Test (p<0.001) and Gait Dynamic Index (p=0.012) of the group subjected to FES.
CONCLUSION: Gait training with FES is more effective than EMS in improving mobility, balance, gait performance and reducing spasticity in stroke patients. The research will help clinicians to select appropriate treatment of foot drop in stroke patients.
Innovative new technologies are helping patients who have suffered a stroke get back to performing everyday tasks like walking and drinking from a cup.
Watching someone who has suffered a stroke try to perform everyday actions such as walking down the sidewalk or even bringing a cup to their lips can serve as a sobering reminder of how fragile full and robust health is, and also serves as an inspiration for those dedicated to improving the lives of those patients.
Steven Plymale, recently named CEO of Toronto-based MyndTec, said his reaction to watching videos of patients using the company’s MyndMove functional electrical stimulation (FES) rehabilitation system was one of the reasons he joined MyndTec.
“They are very compelling,” Plymale said of the demonstration videos, “and, to be honest with you, were one of the visceral reasons why I took this job. It really is technology we have to get out there.”
MyndMove’s potential market just increased exponentially with recent 510(k) marketing clearance from the U.S. Food and Drug Administration. Plymale said MyndTec has already sent several units of the MyndMove system—which uses an eight-channel electrode array programmable with more than 30 protocols to specifically target muscles in the arm—to a partner institution in the U.S. for a pilot.
“Meanwhile, we have had lots of facilities reach out once they heard of the FDA clearance actively trying to get us to work with them both in terms of further research and also in the commercial setting,” Plymale said.
The MyndMove technology, which received Health Canada approval for clinical use in 2014, is based on repeated stimulation of targeted muscles by the FES system (activated by a therapist who has asked a patient to try a specific movement, such as lifting a cup to the mouth or grasping a pen). The stimulation causes muscles to contract and the movement sends a signal from the muscle to the brain.
Based on the concept of neuroplasticity, this coordinated effort trains a new neural pathway that enables improvement and recovery of voluntary movement. The technology was born nearly a decade ago in the research lab of Milos Popovic at the University of Toronto; it is just one example of cutting-edge technology aiding stroke patients, plus some with spinal cord and traumatic brain injuries, to regain more normal function in everyday movements.
From Battlefield To Rehab
While MyndMove aims to improve arm and hand function, another emerging, early-stage technology, is attempting to help stroke patients regain a more natural walking gait. The technology, a soft “exosuit” from Marlborough, Mass.-based ReWalk Robotics, will be entering pre-clinical trials early in 2018.
The exosuit is the product of a collaborative agreement between ReWalk and Harvard University’s Wyss Institute for Biologically Inspired Engineering, and a salient example of how publicly-funded research for one idea can be re-purposed in other areas. The exosuit research began in 2012 as a Defense Advanced Research Projects Agency (DARPA) project intended for the battlefield.
“We started to call it the exosuit because there is no rigid component,” Kathleen O’Donnell, the program lead for Wyss Institute’s medical exosuit program, said. “It does not restrict movement like an exoskeleton might. The first suits were developed to help able-bodied soldiers carry heavy loads and walk long distances. The purpose was to reduce the metabolic burden on them. They often carry 100 or more pounds of equipment on long marches and the goal was to make them less fatigued when they got to their destination.
“About a year or so into that program, we started looking at where we could find more medical applications of this same technology. We talked to clinicians in the Boston area, and it seemed like stroke was a really good application area that could benefit from this type of technology. The reason for that is that a stroke patient who could benefit from this has some residual walking capacity – it’s not somebody who requires total support in order to walk, but they need a little help in learning how to walk better.”
The exosuit is powered by a motor unit worn on a waist belt, which activates sheathed Bowden cables anchored in two spots: one in a calf-worn fabric sleeve and one in the insole of the shoe the unit is activating to achieve a more natural gait.
ReWalk already markets a rigid exoskeleton for people who have suffered a spinal cord injury who are unable to walk unassisted, and O’Donnell said the exosuit collaboration is meant for a different market—”with the exosuit we’re taking somebody with some underlying ability to walk and we are injecting small levels of assistance at critical times in their gait cycle to improve their walking ability and coordination rather than taking over for them.”
ReWalk CEO Larry Jasinski said the upcoming trial is not expected to enroll a large number of patients – comparable trials have consisted of 40 patients or so – and also said the trial is in the middle of IRB approval at four top research institutions nationwide.
Jasinski said the Wyss Institute researchers had shown the device worked, but didn’t have a product that would meet commercial requirements.
“It could not have gotten past the FDA, would not have been durable enough for a rehab lab and use by 100 patients, and it wasn’t really designed for home use,” he said. “And that’s why this relationship is so ideal. They are doing a high level of fundamental research that, generally, small companies can not afford to do. They are making it work for that individual situation. We are going to be able to take it through the FDA, through the reimbursement processes, and manufacture it at a price point with the quality control and functional level that can meet a mass audience. That is why it’s a good marriage.”