Advances in the Understanding and Treatment of Stroke Impairment Using Robotic Devices

Rehabilitation of gait after stroke: a review towards a top-down approach

This document provides a review of the techniques and therapies used in gait rehabilitation after stroke. It also examines the possible benefits of including assistive robotic devices and brain-computer interfaces in this field, according to a top-down approach, in which rehabilitation is driven by neural plasticity.The methods reviewed comprise classical gait rehabilitation techniques (neurophysiological and motor learning approaches), functional electrical stimulation (FES), robotic devices, and brain-computer interfaces (BCI).From the analysis of these approaches, we can draw the following conclusions. Regarding classical rehabilitation techniques, there is insufficient evidence to state that a particular approach is more effective in promoting gait recovery than other. Combination of different rehabilitation strategies seems to be more effective than over-ground gait training alone. Robotic devices need further research to show their suitability for walking training and their effects on over-ground gait. The use of FES combined with different walking retraining strategies has shown to result in improvements in hemiplegic gait. Reports on non-invasive BCIs for stroke recovery are limited to the rehabilitation of upper limbs; however, some works suggest that there might be a common mechanism which influences upper and lower limb recovery simultaneously, independently of the limb chosen for the rehabilitation therapy. Functional near infrared spectroscopy (fNIRS) enables researchers to detect signals from specific regions of the cortex during performance of motor activities for the development of future BCIs. Future research would make possible to analyze the impact of rehabilitation on brain plasticity, in order to adapt treatment resources to meet the needs of each patient and to optimize the recovery process.

Efficacy of a hybrid assistive limb in post-stroke hemiplegic patients: a preliminary report

Background

Robotic devices are expected to be widely used in various applications including support for the independent mobility of the elderly with muscle weakness and people with impaired motor function as well as support for nursing care that involves heavy laborious work. We evaluated the effects of a hybrid assistive limb robot suit on the gait of stroke patients undergoing rehabilitation.

Methods

The study group comprised 16 stroke patients with severe hemiplegia. All patients underwent gait training. Four patients required assistance, and 12 needed supervision while walking. The stride length, walking speed and physiological cost index on wearing the hybrid assistive limb suit and a knee-ankle-foot orthosis were compared.

Results

The hybrid assistive limb suit increased the stride length and walking speed in 4 of 16 patients. The patients whose walking speed decreased on wearing the hybrid assistive limb suit either had not received sufficient gait training or had an established gait pattern with a knee-ankle-foot orthosis using a quad cane. The physiological cost index increased after wearing the hybrid assistive limb suit in 12 patients, but removal of the suit led to a decrease in the physiological cost index values to equivalent levels prior to the use of the suit.

Conclusions

Although the hybrid assistive limb suit is not useful for all hemiplegic patients, it may increase the walking speed and affect the walking ability. Further investigation would clarify its indication for the possibility of gait training.

Rehabilitation--emerging technologies, innovative therapies, and future objectives

Stroke is the leading cause of long-term disability. The goal of stroke rehabilitation is to improve recovery in the years after a stroke and to decrease long-term disability. This article, titled "Rehabilitation--Emerging Technologies, Innovative Therapies, and Future Objectives" gives evidence-based information on the type of rehabilitation approaches that are effective to improve functional mobility and to address cognitive impairments. We review the importance of taking a translational approach to neurorehabilitation, considering the interaction of motor and cognitive systems, skilled learned purposeful limb movement, and spatial navigation ability. Known biologic mechanisms of neurorecovery are targeted in relation to technology implemented by members of the multidisciplinary team. Results from proof-of-concept, within subjects, and randomized controlled trials are presented, and the implications for optimal stroke rehabilitation strategies are discussed. Developing clinical practices are highlighted and future research directions are proposed with goals to provide insight on what the next steps are for this burgeoning discipline.

The development of an adaptive upper-limb stroke rehabilitation robotic system

Background

Stroke is the primary cause of adult disability. To support this large population in recovery, robotic technologies are being developed to assist in the delivery of rehabilitation. This paper presents an automated system for a rehabilitation robotic device that guides stroke patients through an upper-limb reaching task. The system uses a decision theoretic model (a partially observable Markov decision process, or POMDP) as its primary engine for decision making. The POMDP allows the system to automatically modify exercise parameters to account for the specific needs and abilities of different individuals, and to use these parameters to take appropriate decisions about stroke rehabilitation exercises.

Methods

The performance of the system was evaluated by comparing the decisions made by the system with those of a human therapist. A single patient participant was paired up with a therapist participant for the duration of the study, for a total of six sessions. Each session was an hour long and occurred three times a week for two weeks. During each session, three steps were followed: (A) after the system made a decision, the therapist either agreed or disagreed with the decision made; (B) the researcher had the device execute the decision made by the therapist; (C) the patient then performed the reaching exercise. These parts were repeated in the order of A-B-C until the end of the session. Qualitative and quantitative question were asked at the end of each session and at the completion of the study for both participants.

Results

Overall, the therapist agreed with the system decisions approximately 65% of the time. In general, the therapist thought the system decisions were believable and could envision this system being used in both a clinical and home setting. The patient was satisfied with the system and would use this system as his/her primary method of rehabilitation.

Conclusions

The data collected in this study can only be used to provide insight into the performance of the system since the sample size was limited. The next stage for this project is to test the system with a larger sample size to obtain significant results.

Effective Game use in Neurorehabilitation

Games possess highly favourable attributes to bring to the field of neurorehabilitation by means of providing motivation and goal-directed exercise tasks. For the use of games to be effectively integrated in the commercial and clinical rehabilitation marketplace, it is necessary that a unified and comprehensive rehabilitation gaming platform be developed following principles of user-centered design. The needed platform must contain compatible modules for the planning and execution of treatment as well as progress assessment, and its development must take into consideration the needs and viewpoints of the involved stakeholders and the required supporting factors, including: patient, prescriber, therapist, care-provider, family, clinic, as well as supporting scientific evidence, technology, and policy. A proposed platform and needed components are explained and an example prototype rehabilitation platform is provided for discussion.

Assessment of the assistive performance of an ankle exerciser using electromyographic signals

This paper presents the design of an admittance-based assistive controller and preliminary experimental results for a high performance parallel robot used for ankle rehabilitation. The goal of this work was to design a suitable control algorithm for diagnosis, training and rehabilitation of the ankle in presence of musculoskeletal injuries. An admittance control technique is used to perform patient-active exercises with and without motion assistance. Electromyographic (EMG) signals are used to evaluate patient's effort during training/exercising. The results indicate the great potential of the rehabilitation device as a tool to fasten and improve the ankle therapies outcome.

Interventions to promote upper limb recovery in stroke survivors with severe paresis: a systematic review

PURPOSE

To investigate the effect of interventions that promote upper limb (UL) recovery in stroke survivors with severe paresis.

METHODS

A systematic search of the scientific literature from January 1970 to March 2009 was conducted using CINAHL, Cochrane, PEDro, Pubmed and Web of Science. keywords used included stroke, severe, hemiplegia, UL, task-oriented, robot, non-robot and electrical stimulation. Methodological quality of the studies was assessed using the PEDro rating scale. Studies were grouped into one of three intervention categories: robotic therapy, electrical stimulation or 'other' therapy.

RESULTS

Seventeen randomised controlled trials met the inclusion criteria. A 'best evidence synthesis' indicated strong evidence that robotic therapy provides a large beneficial effect and limited evidence that electrical stimulation and 'other' interventions provide a large beneficial effect on function. There is no evidence that these interventions influence use of the arm in everyday tasks.

CONCLUSION

There are a number of newly developed interventions that enable stroke survivors with severe paresis to actively participate in task-oriented practice to promote UL recovery. While these interventions offer some promise for stroke survivors with severe paresis, ultimately, the effectiveness of these interventions will be dependent on whether they lead to restoration of function to the point at which the stroke survivor can practice everyday tasks.

Translating research into clinical practice: integrating robotics into neurorehabilitation for stroke survivors

Technological advances continue to infuse the field of neurorehabilitation with both excitement and apprehension. A challenge for clinicians is to determine which of the growing number of devices or interventions available should be incorporated into their clinical practice, and when and with whom they should be offered, in order to best assist their patients in attaining the highest level of function and quality of life. Robotics is one area of technology that has seen robust growth in rehabilitation applications, so much so that the presence of robotic devices in rehabilitation centers has become an expectation among patients, their caregivers, and therapists. Although rehabilitation robotic devices afford the opportunity to provide high doses of repetitive movement in a reliable and controllable manner, the role they play in the continuum of clinical care remains uncertain. The focus of this article is on translating the empirical evidence related to the application of rehabilitation robotics for improving lower limb and walking function in a manner that the clinician, or any stakeholder, will be able to incorporate relevant findings into clinical practice. A process is outlined and applied to a recent review of the literature related to the use of robotics for the treatment of lower limb and walking function in persons with stroke. This process provides the reader with a tool that can be applied to the translation and implementation of evidence related to any intervention for any client with neurological injury or disease.

Design of a series visco-elastic actuator for multi-purpose rehabilitation haptic device

Background

Variable structure parallel mechanisms, actuated with low-cost motors with serially added elasticity (series elastic actuator - SEA), has considerable potential in rehabilitation robotics. However, reflected masses of a SEA and variable structure parallel mechanism linked with a compliant actuator result in a potentially unstable coupled mechanical oscillator, which has not been addressed in previous studies.

Methods

The aim of this paper was to investigate through simulation, experimentation and theoretical analysis the necessary conditions that guarantee stability and passivity of a haptic device (based on a variable structure parallel mechanism driven by SEA actuators) when in contact with a human. We have analyzed an equivalent mechanical system where a dissipative element, a mechanical damper was placed in parallel to a spring in SEA.

Results

The theoretical analysis yielded necessary conditions relating the damping coefficient, spring stiffness, both reflected masses, controller's gain and desired virtual impedance that needs to be fulfilled in order to obtain stable and passive behavior of the device when in contact with a human. The validity of the derived passivity conditions were confirmed in simulations and experimentally.

Conclusions

These results show that by properly designing variable structure parallel mechanisms actuated with SEA, versatile and affordable rehabilitation robotic devices can be conceived, which may facilitate their wide spread use in clinical and home environments.

Towards brain-robot interfaces in stroke rehabilitation

A neurorehabilitation approach that combines robot-assisted active physical therapy and Brain-Computer Interfaces (BCIs) may provide an additional mileage with respect to traditional rehabilitation methods for patients with severe motor impairment due to cerebrovascular brain damage (e.g., stroke) and other neurological conditions. In this paper, we describe the design and modes of operation of a robot-based rehabilitation framework that enables artificial support of the sensorimotor feedback loop. The aim is to increase cortical plasticity by means of Hebbian-type learning rules. A BCI-based shared-control strategy is used to drive a Barret WAM 7-degree-of-freedom arm that guides a subject's arm. Experimental validation of our setup is carried out both with healthy subjects and stroke patients. We review the empirical results which we have obtained to date, and argue that they support the feasibility of future rehabilitative treatments employing this novel approach.

Role of Robotics in Neurorehabilitation

Over the past decade, rehabilitation hospitals have begun to incorporate robotics technologies into the daily treatment schedule of many patients. These interventions hold greater promise than simply replicating traditional therapy, because they allow therapists an unprecedented ability to specify and monitor movement features such as speed, direction, amplitude, and joint coordination patterns and to introduce controlled perturbations into therapy. We argue that to fully realize the potential of robotic devices in neurorehabilitation, it is necessary to better understand the specific aspects of movement that should be facilitated in rehabilitation. In this article, we first discuss neurorecovery in the context of motor control and learning principles that can provide guidelines to rehabilitation professionals for enhancing recovery of motor function. We then discuss how robotic devices can be used to support such activities.

Clinical training and competency guidelines for using robotic devices

With the increasing popularity of robotic devices in rehabilitation centers worldwide (e.g. Lokomat(®), ZeroG(®), ReoGo, InMotion 2.0, and Biodex System 4), there is a need for guidelines to ensure proper training and evaluation of therapists on the safe and effective use of these devices. Here, we present training tools and guidelines that were based on the recommendations of several device manufacturers and a user-group made up of clinicians and therapists. The training tools consist of a detailed user manual, clinical manual, hand-on training, video training and web based training tools. We also present procedures for evaluating user competency after they have completed detailed training. We believe that the comprehensive training and competency evaluation guidelines presented here will help ensure that rehabilitation robotic devices are used properly. This in turn will lead to more effective interventions and reduce the likelihood of injury.

Universal haptic drive: a robot for arm and wrist rehabilitation

In this paper we present a universal haptic drive (UHD), a device that enables rehabilitation of either arm ("ARM" mode) or wrist ("WRIST" mode) movement in two degrees-of-freedom. The mode of training depends on the selected mechanical configuration, which depends on locking/unlocking of a passive universal joint. Actuation of the device is accomplished by utilizing a series elastic actuation principle, which enables use of off-the-shelf mechanical and actuation components. A proportional force control scheme, needed for implementation of impedance control based movement training, was implemented. The device performance in terms of achievable lower and upper bound of viable impedance range was evaluated through adequately chosen sinusoidal movement in eight directions of a planar movement for the "ARM" mode and in eight directions of a combined wrist flexion/extension and forearm pronation/supination movement for the "WRIST" mode. Additionally, suitability of the universal haptic drive for movement training was tested in a series of training sessions conducted with a chronic stroke subject. The results have shown that reliable and repeatable performance can be achieved in both modes of operation for all tested directions.

Stroke rehabilitation: strategies to enhance motor recovery

Recent evidence indicates that the brain can remodel after stroke, primarily through synaptogenesis. Task-specific and repetitive exercise appear to be key factors in promoting synaptogenesis and are central elements in rehabilitation of motor weakness following stroke. Expert medical management ensures a patient is well enough to participate in rehabilitation with minimal distractions due to pain or depression. Contraint-induced motor therapy and body-weight-supported ambulation are forms of exercise that "force use" of an impaired upper extremity. Technologies now in common use include robotics, functional electrical stimulation, and, to a lesser degree, transcranial magnetic stimulation and virtual reality. The data on pharmacological interventions are mixed but encouraging; it is hoped such treatments will directly stimulate brain tissue to recovery. Mitigation of factors preventing movement, such as spasticity, might also play a role. Research evaluating these motor recovery strategies finds them generally good at the movement level but somewhat less robust when looking at functional performance. It remains unclear whether inconsistent evidence for functional improvement is a matter of poor treatment efficacy or insensitive outcome measures.

Kinematic trajectories while walking within the Lokomat robotic gait-orthosis

Background One of the most popular robot assisted rehabilitation devices used is the Lokomat. Unfortunately, not much is known about the behaviors exhibited by subjects in this device. The goal of this study was to evaluate the kinematic patterns of individuals walking inside the Lokomat compared to those demonstrated on a treadmill. Methods Six healthy subjects walked on a treadmill and inside the Lokomat while the motions of the subject and Lokomat were tracked. Joint angles and linear motion were determined for Lokomat and treadmill walking. We also evaluated the variability of the patterns, and the repeatability of measuring techniques. Findings The overall kinematics in the Lokomat are similar to those on a treadmill, however there was significantly more hip and ankle extension, and greater hip and ankle range of motion in the Lokomat (P<0.05). Additionally, the linear movement of joints was reduced in the Lokomat. Subjects tested on repeated sessions presented consistent kinematics, demonstrating the ability to consistently setup and test subjects. Interpretation The reduced degrees of freedom in the Lokomat are believed to be the reason for the specific kinematic differences. We found that despite being firmly attached to the device there was still subject movement relative to the Lokomat. This led to variability in the patterns, where subjects altered their gait pattern from step to step. These results are clinically important as a variable step pattern has been shown to be a more effective gait training strategy than one which forces the same kinematic pattern in successive steps.

Multicenter Randomized Clinical Trial Evaluating the Effectiveness of the Lokomat in Subacute Stroke

Objective. To compare the efficacy of robotic-assisted gait training with the Lokomat to conventional gait training in individuals with subacute stroke. Methods. A total of 63 participants <6 months poststroke with an initial walking speed between 0.1 to 0.6 m/s completed the multicenter, randomized clinical trial. All participants received twenty-four 1-hour sessions of either Lokomat or conventional gait training. Outcome measures were evaluated prior to training, after 12 and 24 sessions, and at a 3-month follow-up exam. Self-selected overground walking speed and distance walked in 6 minutes were the primary outcome measures, whereas secondary outcome measures included balance, mobility and function, cadence and symmetry, level of disability, and quality of life measures. Results. Participants who received conventional gait training experienced significantly greater gains in walking speed ( P = .002) and distance ( P = .03) than those trained on the Lokomat. These differences were maintained at the 3-month follow-up evaluation. Secondary measures were not different between the 2 groups, although a 2-fold greater improvement in cadence was observed in the conventional versus Lokomat group. Conclusions. For subacute stroke participants with moderate to severe gait impairments, the diversity of conventional gait training interventions appears to be more effective than robotic-assisted gait training for facilitating returns in walking ability.

Abnormal joint torque patterns exhibited by chronic stroke subjects while walking with a prescribed physiological gait pattern

Background

It is well documented that individuals with chronic stroke often exhibit considerable gait impairments that significantly impact their quality of life. While stroke subjects often walk asymmetrically, we sought to investigate whether prescribing near normal physiological gait patterns with the use of the Lokomat robotic gait-orthosis could help ameliorate asymmetries in gait, specifically, promote similar ankle, knee, and hip joint torques in both lower extremities. We hypothesized that hemiparetic stroke subjects would demonstrate significant differences in total joint torques in both the frontal and sagittal planes compared to non-disabled subjects despite walking under normal gait kinematic trajectories.

Methods

A motion analysis system was used to track the kinematic patterns of the pelvis and legs of 10 chronic hemiparetic stroke subjects and 5 age matched controls as they walked in the Lokomat. The subject's legs were attached to the Lokomat using instrumented shank and thigh cuffs while instrumented footlifters were applied to the impaired foot of stroke subjects to aid with foot clearance during swing. With minimal body-weight support, subjects walked at 2.5 km/hr on an instrumented treadmill capable of measuring ground reaction forces. Through a custom inverse dynamics model, the ankle, knee, and hip joint torques were calculated in both the frontal and sagittal planes. A single factor ANOVA was used to investigate differences in joint torques between control, unimpaired, and impaired legs at various points in the gait cycle.

Results

While the kinematic patterns of the stroke subjects were quite similar to those of the control subjects, the kinetic patterns were very different. During stance phase, the unimpaired limb of stroke subjects produced greater hip extension and knee flexion torques than the control group. At pre-swing, stroke subjects inappropriately extended their impaired knee, while during swing they tended to abduct their impaired leg, both being typical abnormal torque synergy patterns common to stroke gait.

Conclusion

Despite the Lokomat guiding stroke subjects through physiologically symmetric kinematic gait patterns, abnormal asymmetric joint torque patterns are still generated. These differences from the control group are characteristic of the hip hike and circumduction strategy employed by stroke subjects.

The Effects on Kinematics and Muscle Activity of Walking in a Robotic Gait Trainer During Zero-Force Control

"Assist as needed" control algorithms promote activity of patients during robotic gait training. Implementing these requires a free walking mode of a device, as unassisted motions should not be hindered. The goal of this study was to assess the normality of walking in the free walking mode of the LOPES gait trainer, an 8 degrees-of-freedom lightweight impedance controlled exoskeleton. Kinematics, gait parameters and muscle activity of walking in a free walking mode in the device were compared with those of walking freely on a treadmill. Average values and variability of the spatio-temporal gait variables showed no or small (relative to cycle-to-cycle variability) changes and the kinematics showed a significant and relevant decrease in knee angle range only. Muscles involved in push off showed a small decrease, whereas muscles involved in acceleration and deceleration of the swing leg showed an increase of their activity. Timing of the activity was mainly unaffected. Most of the observed differences could be ascribed to the inertia of the exoskeleton. Overall, walking with the LOPES resembled free walking, although this required several adaptations in muscle activity. These adaptations are such that we expect that Assist as Needed training can be implemented in LOPES.

Effects of robot-assisted therapy on upper limb recovery after stroke: a systematic review

OBJECTIVE

The aim of the study was to present a systematic review of studies that investigate the effects of robot-assisted therapy on motor and functional recovery in patients with stroke.

METHODS

A database of articles published up to October 2006 was compiled using the following Medline key words: cerebral vascular accident, cerebral vascular disorders, stroke, paresis, hemiplegia, upper extremity, arm, and robot. References listed in relevant publications were also screened. Studies that satisfied the following selection criteria were included: (1) patients were diagnosed with cerebral vascular accident; (2) effects of robot-assisted therapy for the upper limb were investigated; (3) the outcome was measured in terms of motor and/or functional recovery of the upper paretic limb; and (4) the study was a randomized clinical trial (RCT). For each outcome measure, the estimated effect size (ES) and the summary effect size (SES) expressed in standard deviation units (SDU) were calculated for motor recovery and functional ability (activities of daily living [ADLs]) using fixed and random effect models. Ten studies, involving 218 patients, were included in the synthesis. Their methodological quality ranged from 4 to 8 on a (maximum) 10-point scale.

RESULTS

Meta-analysis showed a nonsignificant heterogeneous SES in terms of upper limb motor recovery. Sensitivity analysis of studies involving only shoulder-elbow robotics subsequently demonstrated a significant homogeneous SES for motor recovery of the upper paretic limb. No significant SES was observed for functional ability (ADL).

CONCLUSION

As a result of marked heterogeneity in studies between distal and proximal arm robotics, no overall significant effect in favor of robot-assisted therapy was found in the present meta-analysis. However, subsequent sensitivity analysis showed a significant improvement in upper limb motor function after stroke for upper arm robotics. No significant improvement was found in ADL function. However, the administered ADL scales in the reviewed studies fail to adequately reflect recovery of the paretic upper limb, whereas valid instruments that measure outcome of dexterity of the paretic arm and hand are mostly absent in selected studies. Future research into the effects of robot-assisted therapy should therefore distinguish between upper and lower robotics arm training and concentrate on kinematical analysis to differentiate between genuine upper limb motor recovery and functional recovery due to compensation strategies by proximal control of the trunk and upper limb.

Poststroke upper extremity rehabilitation: a review of robotic systems and clinical results

Although the use of robotic devices to address neuromuscular rehabilitative goals represents a promising technological advance in medical care, the large number of systems being developed and varying levels of clinical study of the devices make it difficult to follow and interpret the results in this new field. This article is a review of the current state-of-the-art in robotic applications in poststroke therapy for the upper extremity, written specifically to help clinicians determine the differences between various systems. We concentrate primarily on systems that have been tested clinically. Robotic systems are grouped by rehabilitation application (e.g., gross motor movement, bilateral training, etc.), and, where possible, the neurorehabilitation strategies employed by each system are described. We close with a discussion of the benefits and concerns of using robotics in rehabilitation and an indication of challenges that must be addressed for therapeutic robots to be applied practically in the clinic.

A haptic knob for rehabilitation of hand function

This paper describes a novel two-degree-of-freedom robotic interface to train opening/closing of the hand and knob manipulation. The mechanical design, based on two parallelogram structures holding an exchangeable button, offers the possibility to adapt the interface to various hand sizes and finger orientations, as well as to right-handed or left-handed subjects. The interaction with the subject is measured by means of position encoders and four force sensors located close to the output measuring grasping and insertion forces. Various knobs can be mounted on the interface, including a cone mechanism to train a complete opening movement from a strongly contracted and closed hand to a large opened position. We describe the design based on measured biomechanics, the redundant safety mechanisms as well as the actuation and control architecture. Preliminary experiments show the performance of this interface and some of the possibilities it offers for the rehabilitation of hand function.

Modified constraint-induced therapy extension: using remote technologies to improve function

OBJECTIVE

To determine efficacy of a modified constraint-induced therapy extension (mCITE) protocol, in which persons with stroke participated in therapy sessions via the Internet.

DESIGN

Pre-post, single-blinded case series.

SETTING

Outpatient clinic.

PARTICIPANTS

Four people with stroke who experienced stroke more than 1 year prior to study entry exhibiting upper-limb hemiparesis and nonuse.

INTERVENTION

Subjects participated in online, 30-minute therapy sessions, 3 times a week for 10 weeks using personal computer-based cameras and free network meeting software. During the same period, subjects' less affected hands and wrists were restrained every weekday for 5 hours. Patients completed online logs to document restraint use and activities practiced at home.

MAIN OUTCOME MEASURES

The Motor Activity Log (MAL) and Wolf Motor Function Test (WMFT). We also used a structured interview to ask patients about their satisfaction with the protocol.

RESULTS

After intervention, subjects exhibited marked improvements in more affected arm use (+2.7, +2.06, +1.7, +2,83, respectively), quality of movement (+2.1, +2.1, +2.03, +1.9, respectively), as measured by the MAL, and speed increases while performing WMFT tasks. Subjects' mCITE satisfaction and adherence were high, and motor changes translated to ability to perform valued activities.

CONCLUSIONS

A home-based, modified constraint-induced movement therapy program is feasible and appears to increase more affected arm use and function using commercially available, inexpensive technologies.

Greater reliance on impedance control in the nondominant arm compared with the dominant arm when adapting to a novel dynamic environment

This study investigated differences in adaptation to a novel dynamic environment between the dominant and nondominant arms in 16 naive, right-handed, neurologically intact subjects. Subjects held onto the handle of a robotic manipulandum and executed reaching movements within a horizontal plane following a pseudo-random sequence of targets. Curl field perturbations were imposed by the robot motors, and we compared the rate and quality of adaptation between dominant and nondominant arms. During the early phase of the adaptation time course, the rate of motor adaptation between both arms was similar, but the mean peak and figural error of the nondominant arm were significantly smaller than those of the dominant arm. Also, the nondominant limb's aftereffects were significantly smaller than in the dominant arm. Thus, the controller of the nondominant limb appears to have relied on impedance control to a greater degree than the dominant limb when adapting to a novel dynamic environment. The results of this study imply that there are differences in dynamic adaptation between an individual's two arms.

Pathophysiology of stroke rehabilitation: the natural course of clinical recovery, use-dependent plasticity and rehabilitative outcome

Even though the disruption of motor activity and function caused by stroke is at times severe, recovery is often highly dynamic. Recuperation reflects the ability of the neuronal network to adapt. Next to an unmasking of latent network representations, other adaptive processes, such as excitatory metabolic stress, an imbalance in activating and inhibiting transmission, leading to salient hyperexcitability, or the consolidation of novel connections, prime the plastic capabilities of the system. Rehabilitative interventions may modulate mechanisms of neurofunctional plasticity and influence the natural course after stroke, both positively, but potentially also acting detrimentally. Though routine rehabilitative procedures are an integral part of stroke care, evidence as to their effectiveness remains equivocal. The present review describes the natural course of motor recovery, focusing on ischemic stroke, and discusses use- and training-dependent adaptive effects. It complements a prior article which highlighted the pathophysiology of plasticity. Though the interaction between rehabilitation and plasticity remains elusive, an attempt is made to clarify how and to what extent rehabilitative therapy shapes motor recovery.

Recent trends in robot-assisted therapy environments to improve real-life functional performance after stroke

Upper and lower limb robotic tools for neuro-rehabilitation are effective in reducing motor impairment but they are limited in their ability to improve real world function. There is a need to improve functional outcomes after robot-assisted therapy. Improvements in the effectiveness of these environments may be achieved by incorporating into their design and control strategies important elements key to inducing motor learning and cerebral plasticity such as mass-practice, feedback, task-engagement, and complex problem solving.

This special issue presents nine articles. Novel strategies covered in this issue encourage more natural movements through the use of virtual reality and real objects and faster motor learning through the use of error feedback to guide acquisition of natural movements that are salient to real activities. In addition, several articles describe novel systems and techniques that use of custom and commercial games combined with new low-cost robot systems and a humanoid robot to embody the " supervisory presence" of the therapy as possible solutions to exercise compliance in under-supervised environments such as the home.

Design of a compliantly actuated exo-skeleton for an impedance controlled gait trainer robot

We have designed and built a lower extremity powered exo-skeleton (LOPES) for the training of post-stroke patients. This paper describes the philosophy behind the design of LOPES, motivates the choices that have been made and gives some exemplary results of the ranges of mechanical impedances that can be achieved.