The application of precisely controlled functional electrical stimulation to the shoulder, elbow and wrist for upper limb stroke rehabilitation: a feasibility study.

BACKGROUND: Functional electrical stimulation (FES) during repetitive practice of everyday tasks can facilitate recovery of upper limb function following stroke. Reduction in impairment is strongly associated with how closely FES assists performance, with advanced iterative learning control (ILC) technology providing precise upper-limb assistance. The aim of this study is to investigate the feasibility of extending ILC technology to control FES of three muscle groups in the upper limb to facilitate functional motor recovery post-stroke. METHODS: Five stroke participants with established hemiplegia undertook eighteen intervention sessions, each of one hour duration. During each session FES was applied to the anterior deltoid, triceps, and wrist/finger extensors to assist performance of functional tasks with real-objects, including closing a drawer and pressing a light switch. Advanced model-based ILC controllers used kinematic data from previous attempts at each task to update the FES applied to each muscle on the subsequent trial. This produced stimulation profiles that facilitated accurate completion of each task while encouraging voluntary effort by the participant. Kinematic data were collected using a Microsoft Kinect, and mechanical arm support was provided by a SaeboMAS. Participants completed Fugl-Meyer and Action Research Arm Test clinical assessments pre- and post-intervention, as well as FES-unassisted tasks during each intervention session. RESULTS: Fugl-Meyer and Action Research Arm Test scores both significantly improved from pre- to post-intervention by 4.4 points. Improvements were also found in FES-unassisted performance, and the amount of arm support required to successfully perform the tasks was reduced. CONCLUSIONS: This feasibility study indicates that technology comprising low-cost hardware fused with advanced FES controllers accurately assists upper limb movement and may reduce upper limb impairments following stroke.

Functional electrical stimulation with exercises for standing balance and weight transfer in acute stroke patients: a feasibility randomized controlled trial.

OBJECTIVES: To test parameters needed for the design of a larger trial including the following: 1) identifying eligible participants, recruitment, and retention rates; 2) the feasibility and acceptability of delivering functional electrical stimulation (FES) to the gluteus maximus and quadriceps femoris for acute stroke patients in a hospital rehabilitation setting; 3) the outcome measures; 4) obtaining initial estimates of effect size; and 5) clarifying the relevant control group. MATERIALS AND METHODS: Twenty-one people with acute stroke-mean age = 68 (min to max: 33-87) years; weeks postonset = 4.6 (min to max: 1-14)-were randomized to three groups to receive two weeks of balance training with FES, balance training alone, or usual care. Symmetry in normal standing, weight transfer onto the affected limb, balance, mobility, and speed of walking were assessed before, shortly after the end of training, and two weeks later by a blinded assessor. RESULTS: 1) FES was successfully delivered but not with the planned eight sessions; 2) no trends in favor of FES were found; and 3) 4% of those screened took part but approaching 20% might be recruited in the future, no single outcome measure was suitable for all participants, and more routine physiotherapy was delivered to the control group. CONCLUSIONS: FES is feasible in this patient group but further feasibility and definitive trials are required.

A personalized sensor-controlled microstimulator system for arm rehabilitation poststroke. Part 1: System architecture.

OBJECTIVES: For rehabilitation of the poststroke upper limb in seven subjects, an external sensor-based system controls the timing of five to seven microstimulators implanted near radial nerve branches or their motor points to sequentially extend the elbow, wrist, and fingers with thumb extension and abduction, enabled at the subject's own pace. We hypothesize this system will support sequential activation of affected upper limb muscles intended to improve functional recovery. MATERIALS AND METHODS: Presented here is a personalized sensor-controlled stimulation system, including its architecture, sensor design, and testing of equipment specific to this study, including coils and sensors. RESULTS: All electrical and magnetic tests, and safety tests per International Electrotechnical Commission 60601-1 passed. One sensor type displayed a vulnerability to drop. CONCLUSIONS: The new control system tested safe, met requirements, and allowed each subject to activate the system at their own pace, making the rehabilitation process more acceptable and efficient.

A personalized sensor-controlled microstimulator system for arm rehabilitation poststroke. Part 2: Objective outcomes and patients' perspectives.

OBJECTIVE: To examine the effect of home-based electrical stimulation using closed-loop control of implanted microstimulators on upper limb function and impairment, and subjects' perception of the system. MATERIALS AND METHODS: Six subjects with poststroke hemiparesis, and reduced upper limb function, who had taken part in Phase 1 of the study, were fitted with a personalized closed-loop control system (Phase 2) and used it at home during performance of functional tasks for 12 weeks (Phase 3). Main outcome measures were: Action Research Arm Test (ARAT), Fugl-Meyer upper limb assessment (FMA), and motor control (Tracking Index). Subjects' perception of the system was assessed in a structured interview. RESULTS: Improvement in ARAT (p=0.05), FMA (p=0.02), and Tracking Index (p=0.03) during Phase 3. Five subjects said using the system had changed their lives and improved their function, all performed functional tasks with the system, but external components were inconvenient. CONCLUSIONS: Closed-loop control improved in function. Subjective assessment identified that the external sensors were effective.

Potential for new technologies in clinical practice.

PURPOSE OF REVIEW: Cost-effective neurorehabilitation is essential owing to financial constraints on healthcare resources. Technologies have the potential to contribute but without strong clinical evidence are unlikely to be widely reimbursed. This review presents evidence of new technologies since 2008 and identifies barriers to translation of technologies into clinical practice. RECENT FINDINGS: Technology has not been shown to be superior to intensively matched existing therapies. Research has been undertaken into the development and preliminary clinical testing of novel technologies including robotics, electrical stimulation, constraint-induced movement therapy, assistive orthoses, noninvasive brain stimulation, virtual reality and gaming devices. Translation of the research into clinical practice has been impeded by a lack of robust evidence of clinical effectiveness and usability. Underlying mechanisms associated with recovery are beginning to be explored, which may lead to more targeted interventions. Improvements in function have been demonstrated beyond the normal recovery period, but few trials demonstrate lasting effects. SUMMARY: Technologies, alone or combined, may offer a cost-effective way to deliver intensive neurorehabilitation therapy in clinical and community environments, and have the potential to empower patients to take more responsibility for their rehabilitation and continue with long-term exercise.

A model of the upper extremity using FES for stroke rehabilitation.

A model of the upper extremity is developed in which the forearm is constrained to lie in a horizontal plane and electrical stimulation is applied to the triceps muscle. Identification procedures are described to estimate the unknown parameters using tests that can be performed in a short period of time. Examples of identified parameters obtained experimentally are presented for both stroke patients and unimpaired subjects. A discussion concerning the identification's repeatability, together with results confirming the accuracy of the overall representation, is given. The model has been used during clinical trials in which electrical stimulation is applied to the triceps muscle of a number of stroke patients for the purpose of improving both their performance at reaching tasks and their level of voluntary control over their impaired arm. Its purpose in this context is threefold: Firstly, changes occurring in the levels of stiffness and spasticity in each subject's arm can be monitored by comparing frictional components of models identified at different times during treatment. Secondly, the model is used to calculate the moments applied during tracking tasks that are due to a patient's voluntary effort, and it therefore constitutes a useful tool with which to analyze their performance. Thirdly, the model is used to derive the advanced controllers that govern the level of stimulation applied to subjects over the course of the treatment. Details are provided to show how the model is applied in each case, and sample results are shown.

Therapeutic effectiveness of electric stimulation of the upper-limb poststroke using implanted microstimulators.

OBJECTIVE: To investigate the therapeutic effect of functional exercise augmented by programmable implanted microstimulators on arm and hand function. DESIGN: Before and after study. SETTING: Implantation was performed in a neurosurgery unit, systems were programmed, and tests were conducted in a university laboratory and subjects exercised at home. PARTICIPANTS: Hemiparetic subjects (N=7) with reduced upper-limb function who were at least 12 months poststroke were recruited from the community. No subjects withdrew. INTERVENTION: Microstimulators were implanted into the arms and forearms to activate elbow, wrist, and finger extension, and thumb abduction. After training and programming of the system, subjects underwent 12 weeks of functional home-based exercise with stimulation. MAIN OUTCOME MEASURES: The primary functional measure was the Action Research Arm Test (ARAT). Impairment measures included upper-limb Fugl-Meyer Assessment (FMA) and tests of motor control (tracking index), spasticity (electromyography stretch index) strength, and active range of motion (AROM). The assessor was not blinded, but scores were validated by an independent blinded observer. RESULTS: All subjects were able to perform functional activities at home by using the system. Compliance was excellent, and there were no serious adverse events. Statistically significant improvements were measured (P<.05) in the tracking index (57.3 degrees(2)+/-48.65 degrees(2)), FMA score (6.3+/-3.59), wrist-extensor strength (5.5+/-4.37 N), and wrist AROM (19.3 degrees +/-18.96 degrees). The mean improvement in ARAT score +/- SD of 4.9+/-7.89 was not statistically significant. CONCLUSIONS: This study has shown the feasibility of a programmable implanted microstimulator system used at home to perform functional exercises and a reduction in impairment after 12 weeks.

Poststroke upper-limb rehabilitation using 5 to 7 inserted microstimulators: implant procedure, safety, and efficacy for restoration of function.

OBJECTIVE: To investigate the feasibility of implanting microstimulators to deliver programmed nerve stimulation for sequenced muscle activation to recover arm-hand functions. DESIGN: By using a minimally invasive procedure and local anesthesia, 5 to 7 microstimulators can be safely and comfortably implanted adjacent to targeted radial nerve branches in the arm and forearm of 7 subjects with poststroke paresis. The microstimulators' position should remain stable with no tissue infection and can be programmed to produce effective personalized functional muscle activity with no discomfort for a preliminary 12-week study. Clinical testing, before and after the study, is reported in the accompanying study. SETTING: Microstimulator implantations in a sterile operating room. PARTICIPANTS: Seven adults, with poststroke hemiparesis of 12 months or more. INTERVENTION: Under local anesthesia, a stimulating probe was inserted to identify radial nerve branches. Microstimulators were inserted by using an introducer and were retrievable for 6 days by attached suture. Each device was powered via a radiofrequency link from 2 external cuff coils connected to a control unit. MAIN OUTCOME MEASURES: To achieve low threshold values at the target sites with minimal implant discomfort. Microstimulators and external equipment were monitored over 12 weeks of exercise. RESULTS: Seven subjects were implanted with 41 microstimulators, 5 to 7 per subject, taking 3.5 to 6 hours. Implantation pain levels were 20% more than anticipated. No infections or microstimulator failures occurred. Mean nerve thresholds ranged between 4.0 to 7.7 microcoulomb/cm(2)/phase over 90 days, indicating that cathodes were within 2 to 4 mm of target sites. In 1 subject, 2 additional microstimulators were inserted. CONCLUSIONS: Microstimulators were safely implanted with no infection or failure. The system was reliable and programmed effectively to perform exercises at home for functional restoration.

Patients' perceptions of the benefits and problems of using the ActiGait implanted drop-foot stimulator.

OBJECTIVE: To evaluate patients' perceptions of the benefits and problems associated with using the ActiGait implanted drop-foot stimulator. METHOD: Thirteen participants who had suffered a stroke at least 6 months prior to recruitment, had a drop-foot that affected walking and had taken part in a trial in which an ActiGait drop-foot stimulator had been implanted, completed a postal questionnaire. RESULTS: Users agreed that the ActiGait had a positive effect on walking; they used it regularly and had little difficulty with putting it on and taking it off. Reliability was a greater problem at 90 days than at the final assessment. Ten of the 13 responders either agreed or strongly agreed with the statement that the ActiGait improved their quality of life at 90 days and 9 out of 12 at the final assessment: 11 of the 12 respondents would recommend the ActiGait to others. DISCUSSION AND CONCLUSION: From the users' perspective the ActiGait improved walking, it was reported to be used regularly and it appeared to be easier to use than a surface system. Users were equivocal about the reliability of the system at 90 days, but at the final assessment reliability had improved.

Phase II trial to evaluate the ActiGait implanted drop-foot stimulator in established hemiplegia.

OBJECTIVE: To evaluate a selective implantable drop foot stimulator (ActiGait) in terms of effect on walking and safety. DESIGN: A phase II trial in which a consecutive sample of participants acted as their own controls. SUBJECTS: People who had suffered a stroke at least 6 months prior to recruitment and had a drop-foot that affected walking were recruited from 3 rehabilitation centres in Denmark. METHODS: Stimulators were implanted into all participants. Outcome measures were range of ankle dorsiflexion with stimulation and maximum walking speed and distance walked in 4 minutes. Measurements were applied before implantation, at 90 days and at a long-term follow-up assessment. Changes over time and with and without stimulation are reported. Safety was evaluated by nerve conduction velocity and adverse events. RESULTS: Fifteen participants were implanted and 13 completed the trial. Long-term improvements were detected in walking speed and distance walked in 4 minutes when stimulated, and the orthotic effect of stimulation showed statistically significant improvement. The device did not compromise nerve conduction velocity and no serious device-related adverse events were reported. Technical problems were resolved by the long-term follow-up assessment at which further improvement in walking was observed. CONCLUSION: This trial has evaluated the safety and performance of the device, which was well accepted by patients and did not compromise safety.

The effect of combined use of botulinum toxin type A and functional electric stimulation in the treatment of spastic drop foot after stroke: a preliminary investigation.

OBJECTIVE: To investigate the effect of combined botulinum toxin type A (BTX) and functional electric stimulation (FES) treatment on spastic drop foot in stroke. DESIGN: Nonblinded randomized controlled trial. SETTING: Hospitals. PARTICIPANTS: Consecutive sample of 21 ambulant adults within 1 year after stroke with a spastic drop foot, of whom 18 completed the study. INTERVENTIONS: The treatment group received BTX injections (Dysport) on 1 occasion into the medial and lateral heads of the gastrocnemius (200U each) and tibialis posterior (400U each) muscles and FES, used on a daily basis for 16 weeks to assist walking. Both groups continued with physiotherapy at the same rate. MAIN OUTCOME MEASURES: Walking speed, Physiological Cost Index, Modified Ashworth Scale, Rivermead Motor Assessment, and Medical Outcomes Study 36-Item Short-Form Health Survey. RESULTS: Walking speed increased over 12 weeks in both control (P=.020) and treatment groups (nonstimulated, P=.004; stimulated, P=.042). The baseline corrected (analysis of covariance) increase in mean walking speed at 12 weeks, relative to controls, was.04m/s (95% confidence interval [CI],.003-.090) without stimulation, and.09m/s (95% CI,.031-.150) with stimulation. CONCLUSIONS: Combined treatment effectively improved walking and function. A larger study is needed to quantify the treatment effect and to investigate its impact on quality of life.

A pilot study to investigate the combined use of botulinum neurotoxin type a and functional electrical stimulation, with physiotherapy, in the treatment of spastic dropped foot in subacute stroke.

The objective was to inform sample size calculations for a full randomized controlled trial (RCT). The design included an RCT pilot trial with a 16 week study period, including a 4 week baseline phase. The subjects were adults within 1 year of first stroke, ambulant with a spastic dropped foot. Twenty-one participants were recruited from the stroke services of 4 centers. For intervention all participants received physiotherapy; the treatment group also received botulinum neurotoxin Type A (BoNTA) intramuscular injections to triceps surae (800 U Dysport) and functional electrical stimulation (FES) of the common peroneal nerve to assist walking. The main outcome measure was walking speed. The result was a significant upward trend in median walking speed for both the control (p = 0.02) and treatment groups (nonstimulated p = 0.004, stimulated p = 0.042). Trend lines were different in location (p = 0.04 and p = 0.009, respectively). In conclusion, there is evidence of an additional, beneficial effect of BoNTA and FES. Sufficient information has been gained on the variability of the primary outcome measure to inform sample size calculations for a full RCT to quantify the treatment effect with precision.

A review of portable FES-based neural orthoses for the correction of drop foot.

This paper reviews the technological developments in neural orthoses for the correction of upper motor neurone drop foot since 1961, when the technique was first proposed by Liberson and his co-workers. Drop foot stimulator (DFS) developments are reviewed starting with hard-wired single-channel and multichannel surface functional electrical stimulation (FES) systems, followed by implanted drop foot stimulators, and then continuing with microprocessor-based surface and implanted drop foot stimulators. The review examines the role of artificial and "natural" sensors as replacements for the foot-switch as the primary control sensor in drop foot stimulators. DFS systems incorporating real-time control of FES and completely implanted DFS systems finish the review.