Functional electrical stimulation for walking in paraplegia (original) (raw)
Related papers
2001
The goal of rehabilitation for stroke patients in this research was to improve the volitional coordination of the swing phase and stance phases of gait. Functional neuromuscular stimulation (FNS) is a promising rehabilitation tool for restoring motor control. For our gait training protocols, FNS systems with surface electrodes were impractical. For the rehabilitation protocols that we defined, available implantable electrode designs did not meet desired criteria regarding fracture rate, invasiveness of placement procedures, and maintenance of position at the motor point. The criteria for the new intramuscular (IM) electrode design included minimally invasive electrode placement technique, accurate placement of electrodes, good muscle selectivity, consistency of muscle activation, good position maintenance of the electrode at the motor point, comfortable stimulus, and practical donning time for the system. A percutaneous electrode was designed for placement beneath the skin at the motor point of seven paralyzed or paretic muscles in the lower limb. A single-helical coil lead, a double-helical coil electrode, and fine wire barbs were design features that enhanced the anchoring capability of the electrode. A polypropylene core enhanced electrode durability. Implantation tools were custom-designed to enable accurate 513 electrode placement without incision. We studied 17 subjects with a total of 124 electrodes. With the use of IM electrodes, FNS was provided for 1,413.8 electrode months. During this time, no instances of infection occurred. The measure of electrode integrity showed a 99% electrode survival rate. Throughout the treatment protocols, 93% of the electrodes delivered a good muscle response; 7% (nine electrodes) moved from the motor point and delivered a poor muscle response during the treatment protocol. Anchoring performance was higher for electrodes implanted in muscles that moved the hip (96.0%) and ankle joints (97.45%) compared with electrodes implanted in muscles that moved the knee joint (88.5%). Ninety-seven percent of the electrodes delivered a comfortable stimulus. Three percent delivered a stimulus that was uncomfortable at therapeutic levels and therefore were not used. We achieved gains in subject impairment and disability measures. The system proved to be practical for use in both clinical and home environments.
Technology and Disability, 2005
Seven paraplegic Functional Electrical Stimulation (FES) experienced users volunteered to test a newly developed eight channel stimulation system. The goal was to discover the influence of various stimulation parameters on the gait quality. As additional task the usability should be improved and simplified as much as possible. Commercially available hydrogel electrodes were attached to quadriceps and gluteus muscles to achieve hip and knee extension, to peroneal nerve to elicit flexion reflex and later also to adductor muscles. All patients were positive about the handling of the stimulation system. Especially the wireless remote control was highly approved. First results demonstrate the importance of an amplitude ramp during stimulation onset (0.1-0.4 s) resulting in a smooth and more "natural" movement. For an adequate step length and walking speed the timing of quadriceps and peroneal nerve stimulation at the end of the swing phase are crucial. Experienced patients with a higher walking speed require a short swing phase and an overlap of quadriceps decay and peronaeus onset (0-0.2 s). Activation of the adductor muscles reduces knee abduction and lead to a better knee trajectory during standing up and better leg movement during the swing phase. Patients can perform 15-25 steps per minute with a step length of 20-30 cm. The walking distance until exhaustion or muscle fatigue occurs is 4-60 m. The analysis of the used stimulation sequences brought up guidelines for a fast and effective parameter optimization procedure.
Spinal Cord, 1995
In adult paraplegic subjects one tibialis anterior muscle received daily electrical stimulation for 4 weeks at twice the motor threshold to determine changes of morphological and histochemical profiles (this paper) and of contractile properties (preceding paperV Bilateral biopsies, obtained 4 weeks before, and immediately after, electrical stimulation, were studied for fibre type proportions, fibre diameters, oxidative capacity, microvascu lature and histopathology, Before stimulation the biopsies showed disuse with increased type 2 fibre proportions and decreased oxidative capacity (succinate dehydrogenase (SOH) activity). The effects of two stimulus patternsl were compared. Following stimulation SOH activity increased significantly in all stimulated muscles. Inconsistent changes occurred in fibre type proportions, fibre diameters, capillary density and capillary/fibre ratios, Both stimulus patterns evoked similar results. In five/seven subjects sub sarcolemmal vacuolation was observed, Electrical stimulation for 4 weeks at only twice motor threshold improves oxidative capacity, but different stimulus parameters are probably needed for significant fibre type conversion.
Surface electrical stimulation of skeletal muscle after spinal cord injury
Spinal Cord, 1999
Objective: Examine muscle contractile activity during electrical stimulation (ES) after spinal cord injury (SCI). Setting: General community of Athens, Georgia, USA. Methods: Eight clinically complete SCI adults (C6 to T12) 4+1 (mean+SE) years post injury and eight able-bodied adults were studied. Surface ES was applied to the left m. quadriceps femoris for three sets of 10, 1 s isometric actions (50 Hz trains, 400 ms biphasic pulses, 50 ms phase delay, 1 s : 1 s duty cycle) with 90 s of rest between sets. Current was set to evoke isometric torque that was (1) sucient to elicit knee extension with 2.3 kg attached to the ankle (low level ES), and (2) intended to equal 30% (mid level ES) or 60% of maximal voluntary torque of able-bodied adults (high level ES, able-bodied only). The absolute and relative cross-sectional area (CSA) of m. quadriceps femoris that was stimulated as re¯ected by contrast shift in magnetic resonance images and torque were measured. Results: Six+2, 20+2 and 38+4% of the average CSA of m. quadriceps was stimulated during low, mid and high level ES, respectively, for able-bodied. Corresponding values for SCI for low and mid level ES were greater (61+12 and 92+7%, P=0.0002). Torque was related to the CSA (cm 2 ) of stimulated muscle (Nm=3.536stimulated CSA+13, r 2 =0.68, P=0.0010), thus ES of a greater per cent of m. quadriceps femoris in SCI was attributed to their smaller muscle (24+3 vs 73+5 cm 2 , P=0.0001). The decline in torque ranged from 9+1 to 15+4% within and over sets for low, mid or high level ES in able-bodied. SCI showed greater (P=0.0001) fatigue (19+3 to 47+6%). Conclusion: The territory of muscle activation by surface electrical stimulation varies among SCI patients. Given sucient current, a large portion of the muscle of interest can be stimulated. The resulting torque is modest, however, compared to that attainable in ablebodied individuals due to the small size and limited fatigue resistance of skeletal muscle years after spinal cord injury.
European Journal of Translational Myology, 2014
We will here discuss the following points related to Home-based Functional Electrical Stimulation (h-b FES) as treatment for patients with permanently denervated muscles in their legs: 1. Upper (UMN) and lower motor neuron (LMN) damage to the lower spinal cord; 2. Muscle atrophy/hypertrophy versus processes of degeneration, regeneration, and recovery; 3. Recovery of twitch-and tetanic-contractility by h-b FES; 4. Clinical effects of h-b FES using the protocol of the "Vienna School"; 5. Limitations and perspectives. Arguments in favor of using the Vienna protocol include: 1. Increased muscle size in both legs; 2. Improved tetanic force production after 3-5 months of percutaneous stimulation using long stimulus pulses (> 100 msec) of high amplitude (> 80 mAmp), tolerated only in patients with no pain sensibility; 3. Histological and electron microscopic evidence that two years of h-b FES return muscle fibers to a state typical of two weeks denervated muscles with respect to atrophy, disrupted myofibrillar structure, and disorganized Excitation-Contraction Coupling (E-CC) structures; 4. The excitability never recovers to that typical of normal or reinnervated muscles where pulses less than 1 msec in duration and 25 mAmp in intensity excite axons and thereby muscle fibres. It is important to motivate these patients for chronic stimulation throughout life, preferably standing up against the load of the body weight rather than sitting. Only younger and low weight patients can expect to be able to stand-up and do some steps more or less independently. Some patients like to maintain the h-b FES training for decades. Limitations of the procedure are obvious, in part related to the use of multiple, large surface electrodes and the amount of time patients are willing to use for such muscle training.
Characterization of an electric stimulation protocol for muscular exercise
Annals of Physical and Rehabilitation Medicine, 2011
Objective. -The aim of this study is to evaluate the effect of rest time (ten minutes) on muscular strength production during a training session under electrical stimulation. Patients and methods. -The isometric force output of the quadriceps femoris muscle was recorded during four sessions of stimulation of five minutes (15 maximal contractions: five seconds on and 15 seconds of rest), on 13 healthy adults. These four sessions are spaced out of ten minutes of recovery. The frequency of current is 100 Hz.
Functional Electrical Stimulation of Denervated Muscles: Basic Issues
Artificial Organs, 2005
Spinal-cord injury (SCI) causes a rapid loss in both muscle mass and contractile force, and the process is especially severe when the injury involves spinal motoneurons. By using an adapted stimulation protocol with increased number of stimuli per day, thus increasing the amount of the muscle activity, we were able to improve the condition of the patient's thigh muscles. The perfusion was increased by 100% -480% and muscle fiber size increased by +53%. This is also confirmed by measuring the muscle cross sectional area with computed tomography (CT) of the thigh showing an increase in m. quadriceps area of 34.6%. The electrically induced contraction force was improved by 828% in patients which were paralyzed up to 2 years. An additional effect of this therapy was the better cosmetic appearance of the thigh, that is highly appreciated by the patients. Overall the above mentioned factors are an important contribution for preventing secondary diseases like decubitus ulcers in patients with permanent denervation of lower extremity.
The Journal of Rehabilitation Research and Development, 2008
Computer-controlled electrical stimulation (ES)induced leg cycle ergometer (ES-LCE) exercise can be beneficial for individuals with spinal cord injury (SCI), but exercise performance is often insufficient for eliciting continuous gains in cardiopulmonary training adaptations. The first purpose of this study was to determine whether a modified ES-LCE improved exercise performance and responses compared with the standard ES-LCE. Modifications to the ES-LCE included increased ES current amplitude (140-300 mA), added shank muscle activation, and increased ES firing angle ranges (+55°). The second purpose was to evaluate the effects of a 6-week interval training program (ITP) with this modified methodology on ES-LCE exercise performance, peak metabolic and cardiorespiratory responses, and muscle strength in experienced and novice riders. No significantly different peak values for power output and stroke volume were found for the two systems, but the modified ES-LCE elicited significantly higher peak values for oxygen uptake (+22%), carbon dioxide production (+51%), pulmonary ventilation (+37%), cardiac output (+32%), heart rate (+19%), and blood lactate concentration (+50%). Power output, metabolic rate, and lower-limb muscle strength increased significantly following training. This study showed that an ITP with the modified ES-LCE can elicit marked improvements in ES-LCE performance (peak power output), peak metabolic and cardiorespiratory responses, and muscle strength in men with SCI, even in those subjects whose performance has plateaued during training on the standard ES-LCE.
Functional electrical stimulation of permanently denervated muscles, updated 2020
Bulletin of Restorative Medicine, 2020
Spinal cord injury produces muscle wasting, which is especially severe after the complete and permanent damage of lower motor neurons that occurs in complete Cauda Equina Syndrome. Even in this worst-case scenario, we have shown that permanently denervated Quadriceps muscle can be rescued by surface Functional Electrical Stimulation and a purpose designed home-based rehabilitation regime. Here, our aim is to show that the effects are extended to both antagonist muscles and the skin of the thighs. Before and after 2 years of electrical stimulation, mass and structure of Quadriceps and Hamstrings muscles were quantitated by force measurements. Muscle gross cross section were evaluated using color computed tomography, muscle and skin biopsies by quantitative histology and immunohistochemistry. The treatment produced: a) an increase in cross-sectional area of stimulated muscles; b) an increase in muscle fiber mean diameter; c) improvements in ultrastructural organization; and d) increas...
Neuromuscular Electrical Stimulation for Mobility Support of Elderly
IFMBE Proceedings, 2014
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License (by-nc 3.0) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. The stimulator for neuromuscular electrical stimulation for mobility support of elderly is not very complicated, but for application within "MOBIL" we have some additional demands to fulfill. First we have specific safety issues for this user group. A powerful compliance management system is crucial not only to guide daily application, but for creating hard data for the scientific outcome. We also need to assure easy handling of the stimulator, because the subjects are generally not able to cope with too difficult and complex motor skills. So, we developed five generations of stimulators and optimizing solutions after field tests. We are already planning the sixth generation with wireless control of the stimulation units by the central main handheld control unit. In a prototype, we have implemented a newly available high capacity memory, a breakthrough in "compliance data storage" as they offer the necessary high storage capacity and fast data handling for an affordable prize. The circuit also contains a 3D accelerometer sensor which acts as a further important safety features: if the control unit drops, this event is detected automatically by the sensor and activates an emergency switch-off that disables the stimulation to avoid associated risks. Further, we have implemented a hardware emergence shutdown and other safety measures. Finally, in the last example muscle torque measurements are referenced with compliance data. In the study normalized maximum voluntary contraction (MVC) and maximum stimulation induced contraction (MSC) were assessed in regular checkups along the training period. With additional consideration of adjusted stimulation intensity for training out of the compliance data records we are able to estimate the induced contraction strength, which turned out to amount in average 11% of MVC. This value may seem on a first sight rather low, and ought to be considered in relation to the results at the end of the training period. Therefore the correlation between normalized MVC and normalized MSC was calculated. It is obvious that MVC can increase to strongly variable extent (3 to 65 %), but in few cases also decrease (-4 to 15 %) over the study period. The correlation suggests that an increase of roughly 1 % of normalized MSC can lead to an increase of about 10 % in MVC in the given training conditions. Overall, we can say that we have a stimulator that has turned out to work sufficiently. The most important feature is the integrated compliance recording because this is very useful for interpretation of the study outcome. The electrical stimulation training has shown that even with relatively small induced contraction intensity we still get some increase in the achievable voluntary extension torque.