Milos R. Popovic

Functional Electrical Stimulation

It is important to evaluate closed-loop FES (functional electrical stimulation) control systems using standard time- and frequency-domain performance metrics to facilitate the discussion of results between research groups. Moreover, uniform reporting of the performance of control methods expedites the process of developing clinically useful controllers by concentrating research efforts on promising control designs. In this article, we have focused on FES applications that benefit individuals who have spinal cord injury. However, this technology is also used for rehabilitation after stroke and traumatic brain injury and can potentially be useful for managing the effects of other neuromuscular diseases and conditions.

Rehabilitation of Reaching and Grasping Function in Severe Hemiplegic Patients Using Functional Electrical Stimulation Therapy

Objective. The aim of this study was to establish the efficacy of a therapeutic intervention based on functional electrical stimulation (FES) therapy to improve reaching and grasping function after severe hemiplegia due to stroke. Methods. A total of 21 subjects with acute stroke were randomized into 2 groups, FES plus conventional occupational and physiotherapy (FES group) or only conventional therapy (control group) 5 days a week for 12 to 16 weeks. A third group of 7 subjects with chronic hemiplegia (at least 5 months poststroke) received only FES therapy (chronic group) and pre—post training changes were compared. FES was applied to proximal and then distal muscle groups during specific motor tasks. At baseline and at the end of treatment, grasping function was assessed using the Rehabilitation Engineering Laboratory Hand Function Test, along with more standard measures of rehabilitation outcome. Results. The FES group improved significantly more than the control group in terms of object manipulation, palmar grip torque, pinch grip pulling force, Barthel Index, Upper Extremity Fugl—Meyer scores, and Upper Extremity Chedoke—McMaster Stages of Motor Recovery. The chronic stroke subjects demonstrated improvements in most categories, but the changes were not statistically significant. Conclusions. FES therapy with upper extremity training may be an efficacious intervention in the rehabilitation of reaching and grasping function during acute stroke rehabilitation.

Neuroprostheses for grasping

Abstract In recent years a number of neuroprostheses have been developed and used to assist stroke and spinal cord injured subjects to restore or improve grasping function. These neuroprostheses clearly demonstrated that the targeted group of subjects can significantly benefit from this technology and that functional electrical stimulation (FES) is a viable method for restoring or improving grasping function. In this article the FES technology is briefly explained and some of the better known neuroprostheses for grasping are discussed. Furthermore, a typical population of subjects that can benefit from this technology is indicated as well as the methodology to select and train these subjects to apply the neuroprosthesis in daily living activities. This article also provides a brief summary of the achieved results with the existing neuroprostheses for grasping and discusses some of the challenges this technology is currently facing. [Neurol Res 2002; 24: 443-452]

Functional electrical therapy: retraining grasping in spinal cord injury

Objective:To determine the clinical efficacy of functional electrical therapy in the rehabilitation of grasping function for quadriplegics.Study design:Randomized intervention-versus-control trial.Setting:Rehabilitation hospital for spinal cord injury in Toronto, Canada.Methods:A total of 21 people with new spinal cord injuries ranging from C3 to C7 were randomly assigned to two groups: Control (N=9) and Intervention (N=12). The intervention was functional electrical therapy, which consisted of repetitive grasping exercises using a neuroprosthesis that applied surface electrical stimulation to the arm to generate and/or assist grasping movements. It was applied by registered Occupational Therapists in a clinical setting. Main outcome measures were: Functional Independence Measure (FIM), Spinal Cord Independence Measure (SCIM), and the Rehabilitation Engineering Laboratory Hand Function Test. Consumer perceptions of functional electrical therapy were assessed via qualitative interviews.Results:Differences between the Control and Intervention groups could be observed although they are not significant due to an insufficient number of participants. Consumer perceptions were positive, including improved Activities of Daily Living and self-satisfaction.Conclusion:Functional electrical therapy has the potential to be an effective treatment modality to restore grasping function in quadriplegia. It can be implemented by occupational therapists in a clinical setting. Further research is required to establish suitable indications for participant selection. In addition, a larger number of participants is needed to demonstrate statistical significance of the Functional Electrical Therapy.

Functional Electrical Stimulation for Grasping and Walking: Indications and Limitations

This review describes the state of art in the field of Functional Electrical Stimulation (FES) and its impact on improving grasping and walking functions in acute and chronic Spinal Cord Injured (SCI) patients. It is argued that during the early rehabilitation period the FES systems with surface stimulation electrodes should be used to assist training of hand and leg movements in SCI patients. Our clinical trials have shown that a number of acute SCI patients with impaired walking and grasping functions could improve these functions due to training with an adjustable FES system to the point that they finally did not need the FES system to carry out these tasks. Other acute SCI patients, who did not recover the desired function, were enabled to perform either walking or grasping with the FES assistance. We believe that the subjects who can perform grasping or walking with the help of FES, and still use the neuroprosthesis 6 months after being subjected to the FES training, should consider the FES system as a prosthetic device in Activities of Daily Living (ADL). Despite the significant technical progress achieved in the last 10 to 15 years in the FES field, there is a general consensus that these systems are not sufficiently advanced and that they need further development. The limited acceptance of the FES technology can be in part explained by the fact that it is not completely mature and that the patients still require daily assistance to use the FES systems. Nevertheless the present FES treatments combined with conventional occupational and physical therapy still remain the most promising approach in rehabilitating SCI patients. In this review, advantages and limitations of different FES systems that are used to restore grasping and walking functions are discussed.Spinal Cord (2001) 39, 403–412.

Larger center of pressure minus center of gravity in the elderly induces larger body acceleration during quiet standing.

When an inverted pendulum approximates quiet standing, it is assumed that the distance between the center of pressure and the vertical projection of the center of mass on the ground (COP-COG) reflects the relationship between the controlling and controlled variables of the balance control mechanism, and that the center of mass acceleration (ACC) is proportional to COP-COG. As aging affects the control mechanism of balance during quiet standing, COP-COG must be influenced by aging and, as a result, ACC is influenced by aging as well. The purpose of this study was to test the hypotheses that aging results in an increased COP-COG amplitude and, as a consequence, that ACC becomes larger in the elderly than the young. Fifteen elderly and 11 young subjects stood quietly on a force platform with their eyes open or closed. We found that (1) the standard deviations of COP-COG and ACC were larger in the elderly than in the young, irrespective of the eye condition; (2) COP-COG is proportional to ACC in both age groups, i.e., the inverted pendulum assumption holds true for quiet standing. The results suggest that a change in the control strategy that is due to aging causes a larger COP-COG in the elderly and, as a consequence, that ACC becomes larger as well.

Gait training regimen for incomplete spinal cord injury using functional electrical stimulation

Study design:Case series, and repeated assessments of the same individuals.Objective:To demonstrate the feasibility and efficacy of a multiweek intervention on walking function in people with chronic, incomplete spinal cord injuries.Setting:Rehabilitation hospital for spinal cord injury (SCI) in Toronto, Canada.Methods:A convenience sample of five subjects with chronic, incomplete SCI trained for 12–18 weeks using a new multichannel neuroprosthesis for walking. The following outcome measures were recorded throughout the training period: walking speed, step frequency and average stride length based on a 2-min walk test. Also identified were which walking aids and orthoses subjects preferred to use, and whether they employed a step-to or step-through gait strategy. Follow-up measurements of three subjects were made up to 10 weeks after treatment.Results:All subjects demonstrated significant improvements in walking function over the training period. Four of the subjects achieved significantly increased walking speeds, which were due to increases in both stride length and step frequency. The fifth subject experienced a significant reduction in preferred assistive devices. Follow-up measurements revealed that two subjects walked slightly slower several weeks after treatment, but they still walked significantly faster than at the start of treatment.Conclusion:The gait training regimen was effective for improving voluntary walking function in a population for whom significant functional changes are not expected. This application of functional electrical therapy is viable for rehabilitation of gait in incomplete SCI.

Functional Electrical Stimulation Therapy of Voluntary Grasping Versus Only Conventional Rehabilitation for Patients With Subacute Incomplete Tetraplegia A Randomized Clinical Trial

Background. Functional electrical stimulation therapy (FET) has a potential to improve voluntary grasping among individuals with tetraplegia secondary to traumatic spinal cord injury (SCI). Objective. This single-site, randomized controlled trial examined the efficacy of 40 hours of FET with conventional occupational therapy (COT) compared with COT alone to improve grasping. Methods. Twenty-four subjects with subacute traumatic incomplete SCI (C4-C7, AIS B-D) consented to participate in 40 hours of therapy over 8 weeks, beyond the conventional rehabilitation program. Subjects were randomized to receive FET + COT (n = 9) or COT (n = 12). The key outcomes were changes in Functional Independence Measure (FIM) self-care subscores, Spinal Cord Independence Measure (SCIM) self-care subscores, and Toronto Rehabilitation Institute Hand Function Test (TRI-HFT) performed at baseline and follow-up. Results. At the end of the treatments, the change in mean FIM self-care subscore for the FET + COT group was 20.1 versus 10 (P = .015) for the COT group. Subjects randomized to FET + COT also had greater improvements in the SCIM and TRI-HFT. No longer term follow-up was feasible. Conclusion. FET significantly reduced disability and improved voluntary grasping beyond the effects of considerable conventional upper extremity therapy in individuals with tetraplegia.

Functional electrical stimulation of walking : Function, exercise and rehabilitation

For nearly half a century, functional electrical stimulation (FES) has been used to restore walking for people with paralysis and muscle weakness due to stroke and spinal cord injury. The first applications of the technology were intended to permanently replace lost neuromuscular function. Later, FES-assisted walking was found to have therapeutic benefits that include increased muscle strength, cardiovascular fitness and improved gait function that could be maintained after use of FES was terminated. In this review, we examine some of the major FES-assisted walking systems that have been developed for experimental and commercial purposes over the last four and a half decades, including foot drop stimulators, multichannel stimulators and hybrid orthotic systems.

The Graded Redefined Assessment of Strength Sensibility and Prehension: reliability and validity.

With the advent of new interventions targeted at both acute and chronic spinal cord injury (SCI), it is critical that techniques and protocols are developed that reliably evaluate changes in upper limb impairment/function. The Graded Redefined Assessment of Strength Sensibility and Prehension (GRASSP) protocol, which includes five subtests, is a quantitative clinical upper limb impairment measure designed for use in acute and chronic cervical SCI. The objectives of this study were to: (1) establish the inter-rater and test-retest reliability, and (2) establish the construct and concurrent validity with the International Standards of Neurological Classification of Spinal Cord Injury (ISNCSCI), Spinal Cord Independence Measure II (SCIM), and the Capabilities of Upper Extremity Questionnaire (CUE). The study protocol included repeated administration of the GRASSP to a cross-section of individuals with tetraplegia who were neurologically stable (n=72). ISNCSCI, CUE, and SCIM assessments were also administered. Two assessors examined the individuals over a 7-day period. Reliability was tested with intra-class correlation coefficients; construct validity was established with agreement/discordance analysis between the GRASSP and ISNCSCI sensory and motor items; and concurrent validity was tested with Spearman correlation coefficients. Inter-rater and test-retest reliability for all subtests within the GRASSP were above the hypothesized value of 0.80 (0.84-0.96 and 0.86-0.98, respectively). The GRASSP is about 50% more sensitive (construct validity) than the ISNCSCI when defining sensory and motor integrity of the upper limb; the subtests showed concurrence with the SCIM, SCIM self-care subscale, and CUE. The strongest concurrence to impairment was with self-perception of function (CUE) (0.57-0.83, p<0.0001). The GRASSP was found to demonstrate reliability, construct validity, and concurrent validity for use as a standardized upper limb impairment measure for individuals with tetraplegia.