Chronic motor dysfunction after stroke: recovering wrist and finger extension by electromyography-triggered neuromuscular stimulation

Myoelectrically controlled wrist robot for stroke rehabilitation

BACKGROUND

Robot-assisted rehabilitation is an advanced new technology in stroke rehabilitation to provide intensive training. Post-stroke motor recovery depends on active rehabilitation by voluntary participation of patient's paretic motor system as early as possible in order to promote reorganization of brain. However, voluntary residual motor efforts to the affected limb have not been involved enough in most robot-assisted rehabilitation for patients after stroke. The objective of this study is to evaluate the feasibility of robot-assisted rehabilitation using myoelectric control on upper limb motor recovery.

METHODS

In the present study, an exoskeleton-type rehabilitation robotic system was designed to provide voluntarily controlled assisted torque to the affected wrist. Voluntary intention was involved by using the residual surface electromyography (EMG) from flexor carpi radialis(FCR) and extensor carpi radialis (ECR)on the affected limb to control the mechanical assistance provided by the robotic system during wrist flexion and extension in a 20-session training. The system also applied constant resistant torque to the affected wrist during the training. Sixteen subjects after stroke had been recruited for evaluating the tracking performance and therapeutical effects of myoelectrically controlled robotic system.

RESULTS

With the myoelectrically-controlled assistive torque, stroke survivors could reach a larger range of motion with a significant decrease in the EMG signal from the agonist muscles. The stroke survivors could be trained in the unreached range with their voluntary residual EMG on the paretic side. After 20-session rehabilitation training, there was a non-significant increase in the range of motion and a significant decrease in the root mean square error (RMSE) between the actual wrist angle and target angle. Significant improvements also could be found in muscle strength and clinical scales.

CONCLUSIONS

These results indicate that robot-aided therapy with voluntary participation of patient's paretic motor system using myoelectric control might have positive effect on upper limb motor recovery.

A feasibility study of the effect of multichannel electrical stimulation and gravity compensation on hand function in stroke patients: a pilot study

Many stroke patients have to cope with impaired arm and hand function. As a feasibility study, gravity compensation (GC) and multichannel electrical stimulation (ES) were applied to the forearm of eight stroke patients to study potential effects on dexterity. ES was triggered by positional data of the subject's hand relative to the objects that had to be grasped. Dexterity was evaluated by means of the Box and Blocks Test (BBT). The BBT was performed with four combinations of support; with and without GC and with and without ES. In all patients, it was possible to induce sufficient hand opening for grasping a block of the BBT by means of ES. There was no significant increase in dexterity as measured with the BBT. GC and/or ES did not improve instantaneous dexterity in a small sample of stroke patients although sufficient hand opening was reached in all patients. More research in a larger sample of stroke patients with more specific and more sophisticated control algorithms is needed to explore beneficial effects of GC and ES on hand function in post stroke rehabilitation.

The effects of electromyography-controlled functional electrical stimulation on upper extremity function and cortical perfusion in stroke patients

OBJECTIVE

The relation was investigated between hemiparetic arm function improvement and brain cortical perfusion (BCP) change during voluntary muscle contraction (VOL), EMG-controlled FES (EMG-FES) and simple electrical muscle stimulation (ES) before and after EMG-FES therapy in chronic stroke patients.

METHODS

Sixteen chronic stroke patients with moderate residual hemiparesis underwent 5 months of task-orientated EMG-FES therapy of the paretic arm once or twice a week. Before and after treatment, arm function was clinically evaluated and BCP during VOL, ES and EMG-FES were assessed using multi-channel near-infrared spectroscopy.

RESULTS

BCP in the ipsilesional sensory-motor cortex (SMC) was greater during EMG-FES than during VOL or ES; therefore, EMG-FES caused a shift in the dominant BCP from the contralesional to ipsilesional SMC. After EMG-FES therapy, arm function improved in most patients, with some individual variability, and there was significant improvement in Fugl-Meyer (FM) score and maximal grip strength (GS). Clinical improvement was accompanied by an increase in ipsilesional SMC activation during VOL and EMG-FES condition.

CONCLUSION

The EMG-FES may have more influence on ipsilesional BCP than VOL or ES alone.

SIGNIFICANCE

The sensory motor integration during EMG-FES therapy might facilitate BCP of the ipsilesional SMC and result in functional improvement of hemiparetic upper extremity.

Breathing-controlled Electrical Stimulation (BreEStim) for management of neuropathic pain and spasticity

Electrical stimulation (EStim) refers to the application of electrical current to muscles or nerves in order to achieve functional and therapeutic goals. It has been extensively used in various clinical settings. Based upon recent discoveries related to the systemic effects of voluntary breathing and intrinsic physiological interactions among systems during voluntary breathing, a new EStim protocol, Breathing-controlled Electrical Stimulation (BreEStim), has been developed to augment the effects of electrical stimulation. In BreEStim, a single-pulse electrical stimulus is triggered and delivered to the target area when the airflow rate of an isolated voluntary inspiration reaches the threshold. BreEStim integrates intrinsic physiological interactions that are activated during voluntary breathing and has demonstrated excellent clinical efficacy. Two representative applications of BreEStim are reported with detailed protocols: management of post-stroke finger flexor spasticity and neuropathic pain in spinal cord injury.

Functional Electrical Therapy (FET): Clinical Trial in Chronic Hemiplegic Subjects

Results from a clinical evaluation of Functional Electrical Therapy (FET) in chronic hemiplegic subjects are presented. FET is an intensive exercise that integrates voluntary maximized manipulation and augmented grasping by electrical stimulation of forearm and hand muscles. A total of 16 chronic hemiplegic subjects participated in a six-month long study. The subjects were divided into lower and higher functioning groups based on their capacity to voluntarily extend the wrist and fingers against gravity. Functional Electrical Therapy comprised 30-min electrically assisted daily exercise of the paretic arm for three consecutive weeks. The outcome measures included Upper Extremity Function Test (UEFT), the Drawing Test (DT), and Modified Ashworth Scale (MAS) of spasticity. The UEFT objectively measured the abilities to grasp and manipulate objects during typical daily activities. The DT measured the ability to coordinate shoulder and elbow joints. The MAS assessed the tone of the paretic arm muscles. The control group was formed from hemiplegic subjects that received FET in their acute phase of hemiplegia and were evaluated in our earlier study. The results showed that FET slightly increases the ability to reach and grasp, and decreases absolute mean spasticity of chronic hemiplegic subjects. The gains in UEFT and DT were measurable, yet not statistically significant. The trends of UEFT and DT scores during the therapy (three weeks) were steeper when compared with the trend during follow-up (23 weeks). The changes of the trends during the study suggest that prolonged treatment could lead to bigger gains. We found standard deviations were increased towards the end of follow-up suggesting individual differences in response to either the treatment or the disablement process.

A novel myoelectric pattern recognition strategy for hand function restoration after incomplete cervical spinal cord injury

This study presents a novel myoelectric pattern recognition strategy towards restoration of hand function after incomplete cervical spinal cord Injury (SCI). High density surface electromyogram (EMG) signals comprised of 57 channels were recorded from the forearm of nine subjects with incomplete cervical SCI while they tried to perform six different hand grasp patterns. A series of pattern recognition algorithms with different EMG feature sets and classifiers were implemented to identify the intended tasks of each SCI subject. High average overall accuracies (> 97%) were achieved in classification of seven different classes (six intended hand grasp patterns plus a hand rest pattern), indicating that substantial motor control information can be extracted from partially paralyzed muscles of SCI subjects. Such information can potentially enable volitional control of assistive devices, thereby facilitating restoration of hand function. Furthermore, it was possible to maintain high levels of classification accuracy with a very limited number of electrodes selected from the high density surface EMG recordings. This demonstrates clinical feasibility and robustness in the concept of using myoelectric pattern recognition techniques toward improved function restoration for individuals with spinal injury.

Afferent and efferent activity control in the design of brain computer interfaces for motor rehabilitation

Stroke is a cardiovascular accident within the brain resulting in motor and sensory impairment in most of the survivors. A stroke can produce complete paralysis of the limb although sensory abilities are normally preserved. Functional electrical stimulation (FES), robotics and brain computer interfaces (BCIs) have been used to induce motor rehabilitation. In this work we measured the brain activity of healthy volunteers using electroencephalography (EEG) during FES, passive movements, active movements, motor imagery of the hand and resting to compare afferent and efferent brain signals produced during these motor related activities and to define possible features for an online FES-BCI. In the conditions in which the hand was moved we limited the movement range in order to control the afferent flow. Although we observed that there is a subject dependent frequency and spatial distribution of efferent and afferent signals, common patterns between conditions and subjects were present mainly in the low beta frequency range. When averaging all the subjects together the most significant frequency bin comparing each condition versus rest was exactly the same for all conditions but motor imagery. These results suggest that to implement an on-line FES-BCI, afferent brain signals resulting from FES have to be filtered and time-frequency-spatial features need to be used.

Changes in descending motor pathway connectivity after corticospinal tract lesion in macaque monkey

Damage to the corticospinal tract is a leading cause of motor disability, for example in stroke or spinal cord injury. Some function usually recovers, but whether plasticity of undamaged ipsilaterally descending corticospinal axons and/or brainstem pathways such as the reticulospinal tract contributes to recovery is unknown. Here, we examined the connectivity in these pathways to motor neurons after recovery from corticospinal lesions. Extensive unilateral lesions of the medullary corticospinal fibres in the pyramidal tract were made in three adult macaque monkeys. After an initial contralateral flaccid paralysis, motor function rapidly recovered, after which all animals were capable of climbing and supporting their weight by gripping the cage bars with the contralesional hand. In one animal where experimental testing was carried out, there was (as expected) no recovery of fine independent finger movements. Around 6 months post-lesion, intracellular recordings were made from 167 motor neurons innervating hand and forearm muscles. Synaptic responses evoked by stimulating the unlesioned ipsilateral pyramidal tract and the medial longitudinal fasciculus were recorded and compared with control responses in 207 motor neurons from six unlesioned animals. Input from the ipsilateral pyramidal tract was rare and weak in both lesioned and control animals, suggesting a limited role for this pathway in functional recovery. In contrast, mono- and disynaptic excitatory post-synaptic potentials elicited from the medial longitudinal fasciculus significantly increased in average size after recovery, but only in motor neurons innervating forearm flexor and intrinsic hand muscles, not in forearm extensor motor neurons. We conclude that reticulospinal systems sub-serve some of the functional recovery after corticospinal lesions. The imbalanced strengthening of connections to flexor, but not extensor, motor neurons mirrors the extensor weakness and flexor spasm which in neurological experience is a common limitation to recovery in stroke survivors.

Effects of integrated volitional control electrical stimulation (IVES) on upper extremity function in chronic stroke

We evaluated the efficacy of a novel electromyogram (EMG)-controlled electrical stimulation system, called the integrated volitional control electrical stimulator (IVES), on the recovery of upper extremity motor functions in patients with chronic hemiparetic stroke. Ten participants in the chronic stage (more than 12 months post-stroke with partial paralysis of their wrist and fingers) received treatment with IVES to the extensor carpi radialis and extensor digitorum communis 6 h/day for 5 days. Before and after the intervention, participants were assessed using upper-extremity Fugl-Meyer motor assessment (FMA), the active range of motion (A-ROM), the nine-hole peg test (NHPT), and surface EMG recordings. The upper extremity FMA showed a statistically significant increase from 50.8 ± 5.8 to 56.8 ± 6.2 after the intervention (P < 0.01). The A-ROM of wrist extension was also significantly improved from 36.0° ± 15.4° to 45.0° ± 15.5° (P < 0.01). The NHPT significantly decreased from 85.3 ± 52.0 to 63.3 ± 29.7 (P = 0.04). EMG measurements demonstrated statistically significant improvements in the coactivation ratios for the wrist flexor and extensor muscles after the intervention. This study suggested that 5 days of IVES treatment yields a noticeable improvement in upper extremity motor functions in patients with chronic hemiparetic stroke.

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.

Subject-specific myoelectric pattern classification of functional hand movements for stroke survivors

In this study, we developed a robust subject-specific electromyography (EMG) pattern classification technique to discriminate intended manual tasks from muscle activation patterns of stroke survivors. These classifications will enable volitional control of assistive devices, thereby improving their functionality. Twenty subjects with chronic hemiparesis participated in the study. Subjects were instructed to perform six functional tasks while their muscle activation patterns were recorded by ten surface electrodes placed on the forearm and hand of the impaired limb. In order to identify intended functional tasks, a pattern classifier using linear discriminant analysis was applied to the EMG feature vectors. The classification accuracy was mainly affected by the impairment level of the subject. Mean classification accuracy was 71.3% for moderately impaired subjects (Chedoke Stage of Hand 4 and 5), and 37.9% for severely impaired subjects (Chedoke Stage of Hand 2 and 3). Most misclassification occurred between grip tasks of similar nature, for example, among pinch, key, and three-fingered grips, or between cylindrical and spherical grips. EMG signals from the intrinsic hand muscles significantly contributed to the inter-task variability of the feature vectors, as assessed by the inter-task squared Euclidean distance, thereby indicating the importance of intrinsic hand muscles in functional manual tasks. This study demonstrated the feasibility of the EMG pattern classification technique to discern the intent of stroke survivors. Future work should concentrate on the construction of a subject-specific EMG classification paradigm that carefully considers both functional and physiological impairment characteristics of each subject in the target task selection and electrode placement procedures.

Improving poststroke recovery: neuroplasticity and task-oriented training

Neurorehabilitation is a critical part of the overall process to achieve optimal outcome after stroke. Presently, the field of neurorehabilitation is in transition. New research suggesting novel approaches to optimize functional recovery after stroke is on the horizon, but clear knowledge of the underlying mechanisms of this recovery is still being unraveled. In practice, many rehabilitation centers continue to provide traditional compensatory rehabilitation training while many others are practicing newer, "task-oriented" approaches. A few centers are incorporating new technology, such as computer-based training devices or robotics, into rehabilitation care. This transition is happening because neuroscientific research has shown that neuroplastic changes in the cerebral cortex and in other parts of the central nervous system (CNS) are necessarily linked to motor skill retraining in the affected limbs. Task-oriented training that focuses on the practice of skilled motor performance is the critical link to facilitating neural reorganization and "rewiring" in the CNS. Therefore, whenever possible, task-oriented training at an intense level should be incorporated into the rehabilitation program of any patient with stroke-related motor deficits. Two such task-oriented therapies that should be available at all neurorehabilitation centers are constraint-induced movement therapy and body weight-supported treadmill training. The optimal intensity of training (frequency and duration) is still not clear but is certainly greater than that available in clinical programs. Therefore, the incorporation of automated training devices will be necessary in the future. However, the engineering necessary to make these devices effective, easy to use, affordable, and portable remains a challenge for the next decade of neurologic bioengineering research.

The synergic effects of mirror therapy and neuromuscular electrical stimulation for hand function in stroke patients

Objective

To investigate the synergic effects of mirror therapy and neuromuscular electrical stimulation (NMES) for hand function in stroke patients.

Method

Sixty patients with hemiparesis after stroke were included (41 males and 19 females, average age 63.3 years). Twenty patients had NMES applied and simultaneously underwent mirror therapy. Twenty patients had NMES applied only, and twenty patients underwent mirror therapy only. Each treatment was done five days per week, 30 minutes per day, for three weeks. NMES was applied on the surface of the extensor digitorum communis and extensor pollicis brevis for open-hand motion. Muscle tone, Fugl-Meyer assessment, and power of wrist and hand were evaluated before and after treatment.

Results

There were significant improvements in the Fugl-Meyer assessment score in the wrist, hand and coordination, as well as power of wrist and hand in all groups after treatment. The mirror and NMES group showed significant improvements in the Fugl-Meyer scores of hand, wrist, coordination and power of hand extension compared to the other groups. However, the power of hand flexion, wrist flexion, and wrist extension showed no significant differences among the three groups. Muscle tone also showed no significant differences in the three groups.

Conclusion

Our results showed that there is a synergic effect of mirror therapy and NMES on hand function. Therefore, a hand rehabilitation strategy combined with NMES and mirror therapy may be more helpful for improving hand function in stroke patients than NMES or mirror therapy only.

Interaction of electrical stimulation and voluntary hand movement in SII and the cerebellum during simulated therapeutic functional electrical stimulation in healthy adults

The therapeutic application of functional electrical stimulation (FES) has shown promising clinical results in the rehabilitation of post-stroke hemiplegia. It appears that the effect is optimal when the patterned electrical stimulation is used in close synchrony with voluntary movement, although the neural mechanisms that underlie the clinical successes reported with therapeutic FES are unknown. One possibility is that therapeutic FES takes advantage of the sensory consequences of an internal model. Here, we investigate fMRI cortical activity when FES is combined with voluntary effort (FESVOL) and we compare this activity to that produced when FES and voluntary activity (VOL) are performed alone. FESVOL revealed greater cerebellar activity compared with FES alone and reduced activity bilaterally in secondary somatosensory areas (SII) compared with VOL alone. Reduced activity was also observed for FESVOL compared with FES alone in the angular gyrus, middle frontal gyrus and inferior frontal gyrus. These findings indicate that during the VOL condition the cerebellum predicts the sensory consequences of the movement and this reduces the subsequent activation in SII. The decreased SII activity may reflect a better match between the internal model and the actual sensory feedback. The greater cerebellar activity coupled with reduced angular gyrus activity in FESVOL compared with FES suggests that the cortex may interpret sensory information during the FES condition as an error-like signal due to the lack of a voluntary component in the movement.

Enhanced detection threshold for in vivo cortical stimulation produced by Hebbian conditioning

Normal brain function requires constant adaptation, as an organism learns to associate important sensory stimuli with the appropriate motor actions. Neurological disorders may disrupt these learned associations and require the nervous system to reorganize itself. As a consequence, neural plasticity is a crucial component of normal brain function and a critical mechanism for recovery from injury. Associative, or Hebbian, pairing of pre- and post-synaptic activity has been shown to alter stimulus-evoked responses in vivo; however, to date, such protocols have not been shown to affect the animal's subsequent behavior. We paired stimulus trains separated by a brief time delay to two electrodes in rat sensorimotor cortex, which changed the statistical pattern of spikes during subsequent behavior. These changes were consistent with strengthened functional connections from the leading electrode to the lagging electrode. We then trained rats to respond to a microstimulation cue, and repeated the paradigm using the cue electrode as the leading electrode. This pairing lowered the rat's ICMS-detection threshold, with the same dependence on intra-electrode time lag that we found for the functional connectivity changes. The timecourse of the behavioral effects was very similar to that of the connectivity changes. We propose that the behavioral changes were a consequence of strengthened functional connections from the cue electrode to other regions of sensorimotor cortex. Such paradigms might be used to augment recovery from a stroke, or to promote adaptation in a bidirectional brain-machine interface.

Stimulus-driven changes in sensorimotor behavior and neuronal functional connectivity application to brain-machine interfaces and neurorehabilitation

Normal brain function requires constant adaptation as an organism interacts with the environment and learns to associate important sensory stimuli with appropriate motor actions. Neurological disorders may disrupt these learned associations, potentially requiring new functional pathways to be formed to replace the lost function. As a consequence, neural plasticity is a critical aspect of both normal brain function as well as the response to neurological injury. A brain-machine interface (BMI) represents a unique adaptive challenge to the nervous system. Efferent BMIs have been developed, which harness signals recorded from a tiny proportion of the motor cortex (M1) to effect control of an external device. There is also interest in the development of an afferent BMI that would supply information directly to the brain (e.g., the somatosensory cortex-S1) via electrical stimulation. If a bidirectional BMI that combined these interfaces were to be successful, new functional pathways would be necessary between the artificial inputs and outputs. Indeed, stimulation of S1 that is contingent upon the consequences of motor command signals recorded from M1 might form the basis for artificial Hebbian associations not unlike those driving learning in the normal brain. In this chapter, we review recent developments in both efferent and afferent BMIs, as well as experimental attempts to understand and mimic the Hebbian processes that give rise to plastic changes within the cortex. We have used a rat model to develop the computational and experimental tools necessary to describe changes in the way small networks of sensorimotor neurons interact and process information. We show that by repetitively pairing the recorded spikes of one neuron with electrical stimulation of another or by repetitively pairing electrical stimulation of two neurons, we can strengthen the inferred functional connection between the pair of neurons. We have also used the dual-stimulation protocol to enhance the ability of a trained rat to detect intracortical microstimulation behavioral cues. These results provide an important proof of concept, demonstrating the feasibility of Hebbian conditioning protocols to alter information flow in the brain. In addition to their possible application to BMI research, techniques like this may improve the efficacy of traditional rehabilitation for patients with neurologic injury.

Robotic lower limb exoskeletons using proportional myoelectric control

Robotic lower limb exoskeletons have been built for augmenting human performance, assisting with disabilities, studying human physiology, and re-training motor deficiencies. At the University of Michigan Human Neuromechanics Laboratory, we have built pneumatically-powered lower limb exoskeletons for the last two purposes. Most of our prior research has focused on ankle joint exoskeletons because of the large contribution from plantar flexors to the mechanical work performed during gait. One way we control the exoskeletons is with proportional myoelectric control, effectively increasing the strength of the wearer with a physiological mode of control. Healthy human subjects quickly adapt to walking with the robotic ankle exoskeletons, reducing their overall energy expenditure. Individuals with incomplete spinal cord injury have demonstrated rapid modification of muscle recruitment patterns with practice walking with the ankle exoskeletons. Evidence suggests that proportional myoelectric control may have distinct advantages over other types of control for robotic exoskeletons in basic science and rehabilitation.

Motor recovery after stroke: a systematic review

Loss of functional movement is a common consequence of stroke for which a wide range of interventions has been developed. In this Review, we aimed to provide an overview of the available evidence on interventions for motor recovery after stroke through the evaluation of systematic reviews, supplemented by recent randomised controlled trials. Most trials were small and had some design limitations. Improvements in recovery of arm function were seen for constraint-induced movement therapy, electromyographic biofeedback, mental practice with motor imagery, and robotics. Improvements in transfer ability or balance were seen with repetitive task training, biofeedback, and training with a moving platform. Physical fitness training, high-intensity therapy (usually physiotherapy), and repetitive task training improved walking speed. Although the existing evidence is limited by poor trial designs, some treatments do show promise for improving motor recovery, particularly those that have focused on high-intensity and repetitive task-specific practice.

‘Factors contributing to upper limb recovery after stroke: A survey of stroke survivors in Queensland Australia’

PURPOSE

To identify factors which contribute to upper limb recovery, from the perspective of stroke survivors.

METHOD

A retrospective cross-sectional survey was administered by post to 220 stroke survivors with upper limb impairment who were more than 3 months post-stroke. The content and language for the questionnaire were drawn from a series of focus groups and in-depth interviews with stroke survivors (n = 29). Where possible items or composite scales were replicated or adapted from existing surveys.

RESULTS

Many factors regarding the stroke survivors' commitment to recovery, the type and amount of exercise undertaken and their knowledge of how to progress were associated with self-reported upper limb recovery. The single most important factor was 'use of the arm in everyday tasks', which was independently responsible for more than 12% of the variance in recovery. 'Not enough movement to work with' was the second most important factor, representing the greatest barrier to recovery.

CONCLUSIONS

The findings of this survey highlight many practical day to day factors that may contribute to a stroke survivor's ability to advance the recovery of their upper limb. Stroke recovery services can use this information to tailor their services to ensure these practical concerns are addressed.

A home-based rehabilitation program for the hemiplegic upper extremity by power-assisted functional electrical stimulation

PURPOSE

To assess the effects of daily power-assisted functional electrical stimulation (FES) home program therapy in chronic stroke.

METHODS

A total of 20 consecutively enrolled stroke patients with spastic upper-extremity impairments > 1 year after stroke were recruited for this non-blinded randomized controlled trial. Subjects were assigned to control and FES groups and followed for 5 months. The FES group used a power-assisted FES device to induce greater muscle contraction by electrical stimulation in proportion to the integrated electromyography (EMG) signal picked up on surface electrodes. Target muscles were the extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB), extensor digitorum communis (EDC), extensor indicis proprius (EIP), and deltoid (Del). Patients underwent 30 approximately 60 min FES sessions at home about 6 days/week. Root mean square (RMS) of ECRL, EDC and Del maximum voluntary EMGs, active range of motion (ROM) of wrist and finger extension and shoulder flexion, modified Ashworth scale (MAS), and clinical tests were investigated before and after FES training.

RESULTS

The FES group displayed significantly greater improvements in RMS, active ROM, MAS and functional hand tests, and was able to smoothly perform activities of daily life using the hemiplegic upper extremities.

CONCLUSIONS

Daily power-assisted FES home program therapy can effectively improve wrist and finger extension and shoulder flexion. Proprioceptional sensory feedback might play an important role in power-assisted FES therapy.

Invasive cortical stimulation to promote recovery of function after stroke: a critical appraisal

BACKGROUND AND PURPOSE

Residual motor deficits frequently linger after stroke. Search for newer effective strategies to promote functional recovery is ongoing. Brain stimulation, as a means of directing adaptive plasticity, is appealing. Animal studies and Phase I and II trials in humans have indicated safety, feasibility, and efficacy of combining rehabilitation and concurrent invasive cortical stimulation. However, a recent Phase III trial showed no advantage of the combination. We critically review results of various trials and discuss the factors that contributed to the distinctive result.

SUMMARY OF REVIEW

Regarding cortical stimulation, it is important to determine the (1) location of peri-infarct representations by integrating multiple neuroanatomical and physiological techniques; (2) role of other mechanisms of stroke recovery; (3) viability of peri-infarct tissue and descending pathways; (4) lesion geometry to ensure no alteration/displacement of current density; and (5) applicability of lessons generated from noninvasive brain stimulation studies in humans. In terms of combining stimulation with rehabilitation, we should understand (1) the principle of homeostatic plasticity; (2) the effect of ongoing cortical activity and phases of learning; and (3) that subject-specific intervention may be necessary.

CONCLUSIONS

Future cortical stimulation trials should consider the factors that may have contributed to the peculiar results of the Phase III trial and address those in future study designs.

Disorders of swallowing: palliative care

This article defines palliative care for swallowing disorders as treatment for severe and chronic dysphagia or intractable aspiration when the recovery of normal swallowing is not anticipated and attempts to restore normal swallowing have been unsuccessful. Palliative treatment for dysphagia is not only for the dying patient because patients with difficulty swallowing can live for a long time. Palliative care for dysphagia is aimed at maximizing swallowing function, maintaining pulmonary health, and supporting healthy nutrition despite the impaired ability to swallow. When despite all attempts at intervention a patient becomes totally unable to swallow, the goal of therapy changes toward finding ways to provide adequate nutrition for the patient.

Chronic stroke and aging: the impact of acoustic stimulus intensity on fractionated reaction time

In control samples, intense acoustic "go" stimuli accelerate the central and peripheral motor processes that compose simple reaction time movements. The goal of the current study was to determine whether movements that are initiated to intense acoustic cues facilitate simple reaction times in (1) adults with chronic stroke as compared to age matched controls and (2) in older as compared to younger adults. EMG and force data were collected from three groups (stroke, older adults, and younger adults) during a ballistic wrist and finger extension task. Movements were made to the onset of 80 dB and 107 dB acoustic cues and simple reaction times were fractionated into premotor and motor components. The present findings offer two important contributions to the literature. First, increases in stimulus intensity led to faster motor times in the impaired limb of stroke subjects. Second, increased stimulus intensity led to faster premotor reaction times across all groups, although an age rather than a stroke-specific motor deficit was evidenced, with the younger control group displaying significantly faster premotor times. Findings are integrated with previous evidence concerning post stroke corticospinal tract integrity and are interpreted via mechanisms which address stroke and age-related changes in motoneurons and activity in motor units.

Intramuscular Electrical Stimulation for Upper Limb Recovery in Chronic Hemiparesis: An Exploratory Randomized Clinical Trial

Background. Surface electrical stimulation (ES) has been shown to improve the motor impairment of stroke survivors. However, surface ES can be painful and motor activation can be inconsistent from session to session. Percutaneous intramuscular ES may be an effective alternative. Objective. Evaluate the effectiveness of percutaneous intramuscular ES in facilitating the recovery of the hemiparetic upper limb of chronic stroke survivors. Methods. A total of 26 chronic stroke survivors were randomly assigned to percutaneous intramuscular ES for hand opening (n = 13) or percutaneous ES for sensory stimulation only (n = 13). The intramuscular ES group received cyclic, electromyography (EMG)-triggered or EMG-controlled ES depending on baseline motor status. All participants received 1 hour of stimulation per day for 6 weeks. After completion of ES, participants received 18 hours of task-specific functional training. The primary outcome measure was the Fugl-Meyer Motor Assessment. Secondary measures included the Arm Motor Ability Test and delay and termination of EMG activity. Outcomes were assessed in a blinded manner at baseline, at the end of ES, at the end of functional training, and at 1, 3, and 6 months follow-up. Results. Repeated measure analysis of variance did not yield any significant treatment, or time by treatment interaction effects for any of the outcome measures. Conclusion. Percutaneous intramuscular ES does not appear to be any more effective than sensory ES in enhancing the recovery of the hemiparetic upper limb among chronic stroke survivors. However, because of the exploratory nature of the study and its inherent limitations, conclusions must be drawn with caution.

A novel functional electrical stimulation treatment for recovery of hand function in hemiplegia: 12-week pilot study

BACKGROUND

Loss of finger extension is common after stroke and can severely limit hand function. Contralaterally controlled functional electrical stimulation (CCFES) is a new treatment aimed at restoring volitional finger and thumb extension. A previous pilot study showed reductions in hand impairment after 6 weeks of CCFES, but the effect did not persist after end of treatment.

OBJECTIVE

This study aimed to evaluate the feasibility of achieving greater and more persistent gains with CCFES by increasing the treatment period to 12 weeks.

METHODS

CCFES uses neuromuscular electrical stimulation to open the paretic hand in direct proportion to the degree of volitional opening of the unimpaired contralateral hand, which is detected by an instrumented glove. Three subjects with chronic hemiplegia participated in a 12-week CCFES treatment, which consisted of daily CCFES-assisted active repetitive hand-opening exercises and twice weekly functional task practice with CCFES.

RESULTS

Maximum voluntary finger extension increased by 101 degrees and 68 degrees for subjects 1 and 2, respectively, but subject 3 had no improvement in finger extension. Box and Block score increased by 6, 15, and 7 blocks, and upper extremity Fugl-Meyer score increased by 11, 15, and 7 points for subjects 1, 2, and 3, respectively. The finger extension gains declined at the 1-month and 3-month follow-up for subjects 1 and 2, but the gains in Box and Block and Fugl-Meyer scores persisted at follow-up.

CONCLUSIONS

Greater reductions in hand impairment were achieved by extending the treatment period. The effect and its longevity may be related to baseline impairment level.

Upper extremity improvements in chronic stroke: coupled bilateral load training

BACKGROUND

The current treatment intervention study determined the effect of coupled bilateral training (i.e., bilateral movements and EMG-triggered neuromuscular stimulation) and resistive load (mass) on upper extremity motor recovery in chronic stroke.

METHODS

Thirty chronic stroke subjects were randomly assigned to one of three behavioral treatment groups and completed 6 hours of rehabilitation in 4 days: (1) coupled bilateral training with a load on the unimpaired hand, (2) coupled bilateral training with no load on the unimpaired hand, and (3) control (no stimulation assistance or load).

RESULTS

Separate mixed design ANOVAs revealed improved motor capabilities by the coupled bilateral groups. From the pretest to the posttest, both the coupled bilateral no load and load groups moved a higher number of blocks and demonstrated more regularity in the sustained contraction task. Faster motor reaction times across test sessions for the coupled bilateral load group provided additional evidence for improved motor capabilities.

CONCLUSIONS

Together these behavioral findings lend support to the contribution of coupled bilateral training with a load on the unimpaired arm to improved motor capabilities on the impaired arm. This evidence supports a neural explanation in that simultaneously moving both limbs during stroke rehabilitation training appears to activate balanced interhemispheric interactions while an extra load on the unimpaired limb provides stability to the system.

Neuromuscular electrical stimulation for motor restoration in hemiplegia

Clinical applications of neuromuscular electrical stimulation (NMES) in stroke rehabilitation provide both therapeutic and functional benefits. Therapeutic applications include upper and lower limb motor relearning and reduction of poststroke shoulder pain. There is growing evidence that NMES, especially those approaches that incorporate task-specific strategies, is effective in facilitating upper and lower limb motor relearning. There is also strong evidence that NMES reduces poststroke shoulder subluxation and pain. Functional applications include upper and lower limb neuroprostheses. Lower limb neuroprostheses in the form of peroneal nerve stimulators is effective in enhancing the gait speed of stroke survivors with foot-drop. The development of hand neuroprostheses is in its infancy and must await additional fundamental and technical advances before reaching clinical viability. The limitations of available systems and future developments are discussed.

O envelhecimento cortical e a reorganização neural após o acidente vascular encefálico (AVE): implicações para a reabilitação

Este artigo apresenta uma síntese sobre o envelhecimento do córtex cerebral humano e uma revisão das abordagens para a reabilitação do controle motor após o acidente vascular encefálico (AVE). Na discussão sobre as implicações clínicas na compensação das perdas, é enfatizado que os profissionais de reabilitação devem incentivar os pacientes idosos a usarem os dois membros superiores para a realização das atividades da vida diária (AVDs) ao invés de reforçarem o uso do membro superior não afetado.

Assistive control system using continuous myoelectric signal in robot-aided arm training for patients after stroke

In some stroke rehabilitation programs, robotic systems have been used to aid the patient to train. In this study, a myoelectrically controlled robotic system with 1 degree-of-freedom was developed to assist elbow training in a horizontal plane with intention involvement for people after stroke. The system could provide continuous assistance in extension torque, which was proportional to the amplitude of the subject's electromyographic (EMG) signal from the triceps, and could provide resistive torques during movement. This study investigated the system's effect on restoring the upper limb functions of eight subjects after chronic stroke in a twenty-session rehabilitation training program. In each session, there were 18 trials comprising different combinations of assistive and resistive torques and an evaluation trial. Each trial consisted of five cycles of repetitive elbow flexion and extension between 90 degrees and 0 degrees at a constant velocity of 10 degrees/s. With the assistive extension torque, subjects could reach a more extended position in the first session. After 20 sessions of training, there were statistically significant improvements in the modified Ashworth scale, Fugl-Meyer scale for shoulder and elbow, motor status scale, elbow extension range, muscle strength, and root mean square error between actual elbow angle and target angle. The results showed that the twenty-session training program improved upper limb functions.

Impact of EMG-triggered neuromuscular stimulation of the wrist and finger extensors of the paretic hand after stroke: a systematic review of the literature

OBJECTIVE

To assess whether EMG-triggered neuromuscular electrical stimulation (EMG-NMES) applied to the extensor muscles of the forearm improves hand function after stroke.

DESIGN

Systematic review of randomized controlled trials.

METHODS

A computer-aided literature search up to June 2006 identified articles comparing EMG-NMES of the upper extremity with usual care. Methodological quality was rated on the Physiotherapy Evidence Database scale (PEDro), and the Hedges' g model was used to calculate the summary effect sizes (SES) using fixed or random models depending on heterogeneity.

RESULTS

Eight studies, selected out of 192 hits and presenting 157 patients, were included in quantitative and qualitative analyses. The methodological quality ranged from 2 to 6 points. The meta-analysis revealed non-significant effect sizes in favour of EMG-NMES for reaction time, sustained contraction, dexterity measured with the Box and Block manipulation test, synergism measured with the Fugl-Meyer Motor Assessment Scale and manual dexterity measured with the Action Research Arm test.

CONCLUSION

No statistically significant differences in effects were found between EMG-NMES and usual care. Most studies had poor methodological quality, low statistical power and insufficient treatment contrast between experimental and control groups. In addition, all studies except two investigated the effects of EMG-NMES in the chronic phase after stroke, whereas the literature suggests that an early start, within the time window in which functional outcome of the upper limb is not fully defined, is more appropriate.

Electrical stimulation of the upper extremity in stroke: cyclic versus EMG-triggered stimulation

Objective: To compare the effect of cyclic and electromyography (EMG)-triggered electrical stimulation on motor impairment and function of the affected upper extremity in chronic stroke.

Design: Randomized controlled trial.

Setting: Outpatient clinic of a rehabilitation centre.

Subjects and intervention: Twenty-two subjects in the chronic stage after stroke were randomly assigned to receive either cyclic (n = 11) or EMG-triggered electrical stimulation (n = 11) of the wrist and finger extensor muscles for a six-week period.

Outcome measures: The primary outcome measure was the Action Research Arm test (0—57 points) to assess arm function. Grip strength, Fugl-Meyer Motor Assessment and Motricity Index were secondary outcome measures. Assessments were made at the start of the treatment and after 4, 6 and 12 weeks.

Results: Both groups improved on the Action Research Arm test. The group receiving cyclic stimulation improved by 2.3 points, and the group receiving EMG-triggered stimulation improved by 4.2 points. The difference in functional gain was not statistically significant. Differences in gain on the secondary outcome measures were not significant either.

Conclusion: The present study did not detect a significant difference between EMG-triggered and cyclic electrical stimulation with respect to improvement of motor function of the affected arm in chronic stroke.

Cortical effect and functional recovery by the electromyography-triggered neuromuscular stimulation in chronic stroke patients

We investigated the effect of electromyography (EMG)-triggered neuromuscular electrical stimulation (NMES; EMG-stim) on functional recovery of the hemiparetic hand and the related cortical activation pattern in chronic stroke patients. We enrolled 14 stroke patients, who were randomly assigned to the EMG-stim (n=7) or the control groups (n=7). The EMG-stim was applied to the wrist extensor of the EMG-stim group for two sessions (30 min/session) a day, five times per week for 10 weeks. Four functional tests (box and block, strength, the accuracy index, and the on/offset time of muscle contraction) and functional MRI (fMRI) were performed before and after treatment. fMRI was measured at 1.5 T in parallel with timed finger flexion-extension movements at a fixed rate. Following treatment, the EMG-stim group showed a significant improvement in all functional tests. The main cortical activation change with such functional improvement was shifted from the ipsilateral sensorimotor cortex (SMC) to the contralateral SMC. We demonstrated that 10-week EMG-stim can induce functional recovery and change of cortical activation pattern in the hemiparetic hand of chronic stroke patients.

Design and evaluation of a functional electrical stimulation system for hand sensorimotor augmentation

The aim of this study was to perform a preliminary evaluation of a new method for therapeutic exercise of grasping in patients with upper limb disability. The new method combines active voluntary exercise augmented with electrical stimulation and controlled by using force feedback. The feedback has two functions: automatic control of the intensity of electrical stimulation by minimizing the tracking error, and biofeedback to the patient on the computer screen. The force feedback is realized by the use of a newly designed adjustable hand force measuring device, which comprises two force sensors. The therapy requires from patients to volitionally try to open and close the hand while tracking the target on the screen. The system was evaluated in a pilot study in five healthy and two chronic incomplete tetraplegic subjects. Results in healthy subjects were used for reference and for stimulation controller evaluation. The therapy in incomplete tetraplegic subjects of 45-min daily session delivered during four weeks. The results of pilot study show that augmentation of voluntary grip force control with presented system is possible.

Neurorehabilitation with new functional electrical stimulation for hemiparetic upper extremity in stroke patients

In recent years, our understanding of motor learning, neuroplasticity, and functional recovery after the occurrence of brain lesion has grown significantly. New findings in basic neuroscience have stimulated research in motor rehabilitation. Repeated motor practice and motor activity in a real-world environment have been identified in several prospective studies as favorable for motor recovery in stroke patients. Electrical stimulation can be applied in a variety of ways to the hemiparetic upper extremity following stroke. In this paper, an overview of current research into clinical and therapeutic applications of functional electrical stimulation (FES) is presented. In particular, electromyography (EMG)-initiated electrical muscle stimulation--but not electrical muscle stimulation alone--improves the motor function of the hemiparetic arm and hand. Triggered electrical stimulation is reported to be more effective than untriggered electrical stimulation in facilitating upper extremity motor recovery following stroke. Power-assisted FES induces greater muscle contraction by electrical stimulation in proportion to the voluntary integrated EMG signal picked up, which is regulated by a closed-loop control system. Power-assisted FES and motor point block for antagonist muscles have been applied with good results as a new hybrid FES therapy in an outpatient rehabilitation clinic for patients with stroke. Furthermore, a daily home program therapy with power-assisted FES using new equipment has been able to effectively improve wrist and finger extension and shoulder flexion. Proprioceptive sensory feedback might play an important role in power-assisted FES therapy. Although many physiotherapeutic modalities have been established, conclusive proof of their benefit and physiological models of their effects on neuronal structures and processes are still missing. A multichannel near-infrared spectroscopy study to noninvasively and dynamically measure hemoglobin levels in the brain during functional activity has shown that cerebral blood flow in the sensory-motor cortex on the injured side is higher during a power-assisted FES session than during simple active movement or simple electrical stimulation. Nevertheless, evidence-based strategies for motor rehabilitation are more easily available, particularly for patients with hemiparesis.

The therapeutic effects of myoelectrically controlled robotic system for persons after stroke--a pilot study

In this study, a myoelectrically controlled robotic system with one degree of freedom was developed to assist elbow training in the horizontal plane for patients after stroke. The system could provide assistive extension torque which was proportional to the amplitude of the subject's processed and normalized electromyograhpic (EMG) signal from triceps. The system also provided different resistive torques during movement, which were based on the maximum isometric voluntary extension (MIVE) and flexion (MIVF) torques. A study investigated its effect after 20-session of training for four weeks on the functional improvement of the affected arm in 3 subjects after stroke. Outcome measurements on the muscle strength at the elbow joint showed that there were increases in the MIVE and MIVF torques of the affected arms of all the subjects after the four-week rehabilitation training. The subjects could also reach a more extended position without the assistance of the robotic system than that before the four-week training.

New multi-channel transcutaneous electrical stimulation technology for rehabilitation

Transcutaneous (surface) electrical stimulation (TES) is a widely applied technique for muscle atrophy treatment, muscle force training, endurance training, pain treatment, functional movement therapy, and the restoration of motor functions. We present a new TES technology based on a multi-channel stimulation approach, which allows us to perform real-time spatial and temporal variations of the electrical current density on the skin surface and in deeper tissue layers. This new approach can generate a better muscle selectivity and improved muscle activation patterns compared to state of art TES systems, which operate with predetermined electrode positions. In simulations using a finite element model (FEM) of the distal arm we could show that the nerve activation in the muscle layer is not significantly influenced by the structure of the multi-channel electrode, if the gap between elements is less than 2 mm. Experiments in healthy volunteers allowed us to measure the selectivity of single finger activations. We could also show in stroke subjects that this novel multi-channel approach was able to generate selective finger and wrist extension movements that were strong enough to overcome flexion hyperactivity. For future applications in rehabilitation a full integration of the stimulation hardware into a garment sleeve would be helpful. Once fully integrated, this new technology has a high potential to increase the ease of use, stimulation and wear comfort. It is able to improve muscle selectivity compared to state of the art TES systems, and allows the implementation of a variety of new applications for the medical and consumer market.

Ultrasound evaluation in combination with finger extension force measurements of the forearm musculus extensor digitorum communis in healthy subjects

Background

The aim of this study was to evaluate the usefulness of an ultrasound-based method of examining extensor muscle architecture, especially the parameters important for force development. This paper presents the combination of two non-invasive methods for studying the extensor muscle architecture using ultrasound simultaneously with finger extension force measurements.

Methods

M. extensor digitorum communis (EDC) was examined in 40 healthy subjects, 20 women and 20 men, aged 35–73 years. Ultrasound measurements were made in a relaxed position of the hand as well as in full contraction. Muscle cross-sectional area (CSA), pennation angle and contraction patterns were measured with ultrasound, and muscle volume and fascicle length were also estimated. Finger extension force was measured using a newly developed finger force measurement device.

Results

The following muscle parameters were determined: CSA, circumference, thickness, pennation angles and changes in shape of the muscle CSA. The mean EDC volume in men was 28.3 cm³ and in women 16.6 cm³. The mean CSA was 2.54 cm² for men and 1.84 cm² for women. The mean pennation angle for men was 6.5° and for women 5.5°. The mean muscle thickness for men was 1.2 cm and for women 0.76 cm. The mean fascicle length for men was 7.3 cm and for women 5.0 cm. Significant differences were found between men and women regarding EDC volume (p < 0.001), CSA (p < 0.001), pennation angle (p < 0.05), muscle thickness (p < 0.001), fascicle length (p < 0.001) and finger force (p < 0.001). Changes in the shape of muscle architecture during contraction were more pronounced in men than women (p < 0.01). The mean finger extension force for men was 96.7 N and for women 39.6 N. Muscle parameters related to the extension force differed between men and women. For men the muscle volume and muscle CSA were related to extension force, while for women muscle thickness was related to the extension force.

Conclusion

Ultrasound is a useful tool for studying muscle architectures in EDC. Muscle parameters of importance for force development were identified. Knowledge concerning the correlation between muscle dynamics and force is of importance for the development of new hand training programmes and rehabilitation after surgery.