Stroke Survivors Control the Temporal Structure of Variability During Reaching in Dynamic Environments

Learning to control forces is known to reduce the amount of movement variability (e.g., standard deviation; SD) while also altering the temporal structure of movement variability (e.g., approximate entropy; ApEn). Such variability control has not been explored in stroke survivors during reaching movements in dynamic environments. Whether augmented feedback affects such variability control, is also unknown. Chronic stroke survivors, assigned randomly to a control/experimental group, learned reaching movements in a dynamically changing environment while receiving either true feedback of their movement (control) or augmented visual feedback (experimental). Hand movement variability was analyzed using SD and ApEn. A significant change in variability was determined for both SD and ApEn. Post hoc tests revealed that the significant decrease in SD was not retained after a week. However, the significant increase in ApEn, determined on both days of training, showed significant retention effects. In dynamically changing environments, chronic stroke survivors reduced the amount of movement variability and made their movement patterns less repeatable and possibly more flexible. These changes were not affected by augmented visual feedback. Moreover, the learning patterns characteristically involved the control of the nonlinear dynamics rather than the amount of hand movement variability. The absence of transfer effects demonstrated that variability control of hand movement after a stroke is specific to the task and the environment

Kinematic changes following robotic-assisted upper extremity rehabilitation in children with hemiplegia : dosage effects on movement time

Indiana University-Purdue University Indianapolis (IUPUI)Background: Rehabilitation Robotics (RR) has become a more widely used and better understood treatment intervention and research tool in the last 15 years. Traditional research involves pre and post-test outcomes, making it difficult to analyze changes in behavior during the treatment process. Harnessing kinematics captured throughout each treatment allows motor learning to be quantified and questions of application and dosing to be answered. Objective: The aims of this secondary analysis were: (i) to investigate the impact of treatment presentation during RR on upper extremity movement time (mt) in children with hemiplegic cerebral palsy (CP) and (ii) to investigate the impact of training structure (dose and intensity) on mt in children with CP participating in RR. Methods: Subjects completed 16 intervention sessions of RR (2 x week; 8 weeks) with a total of 1,024 repetitions of movement per session and three assessments: pre, post and 6 month f/u. During each assessment and intervention, subjects completed “one-way record” assessments tracking performance on a planar task without robotic assistance. Kinematics from these records were extracted to assess subject performance over the course of and within sessions. Results: For all participants, a significant decrease in mt was found at post-test and follow-up. No significant differences were found in mt for age, severity or group placement. A significant interaction was found between treatment day, block and group (p = .033). Significant mt differences were found between the three blocks of intervention within individual days (p = .001). Specifically, significant differences were found over the last block of treatment (p = .032) and between successive treatment days (p = .001). Conclusion: The results indicate that for children with CP participating in RR, the number of repetitions per session is important. We hypothesized that children’s performance would plateau during a treatment day as attention waned, the opposite proved to be true. Despite the high-number of repetitions and associated cognitive demand, subjects’ performance actually trended upwards throughout the 1,024 repetitions suggesting that children were able to tolerate and learn from a high volume of repetitions

Effect Of Error Augmentation Training Strategy On Engagement In Rehabilitation Therapy

There are numerous strategies in the field of stroke rehabilitation which help to enhance the patients’ engagement in the rehabilitation exercises. One of the most updated strategies for improving an individual’s motor rehabilitation includes a robotic interface known as error augmentation. The goal of this study was to evaluate three error augmentation training strategies (error amplification (EA), random forces disturbances (RD) and training without perturbations (NP)) based on the engagement level during the rehabilitation exercise of healthy individuals. This will form the framework for future application to sub-acute stroke survivors using the developed lower limb stroke rehabilitation system (LLSRS). Five healthy subjects (5 males; age: 22.8 ± 0.45) performed the experiment using the designed LLSRS. The training task consisted of tracking a targeted visual indicator bar presented on a LabVIEW graphic user interface by controlling the amplitude of force applied by the leg. The brain response and sustained engagement of the subject when responding to the different training strategies are studied using electroencephalogram (EEG) obtained from the measured signals of the brain activities based on the Emotiv EPOC+ headset during the exercise. The results demonstrated that the error-augmentation training paradigms can improve the engagement level (p0.05) between the effectiveness of the training strategies in enhancing the engagement of a subject. A clinical trial will be required to further investigate the efficacy of the rehabilitation treatment using LLSRS in providing similar training advantage to sub-acute stroke patients

Upper limb soft robotic wearable devices: a systematic review

Introduction: Soft robotic wearable devices, referred to as exosuits, can be a valid alternative to rigid exoskeletons when it comes to daily upper limb support. Indeed, their inherent flexibility improves comfort, usability, and portability while not constraining the user’s natural degrees of freedom. This review is meant to guide the reader in understanding the current approaches across all design and production steps that might be exploited when developing an upper limb robotic exosuit. Methods: The literature research regarding such devices was conducted in PubMed, Scopus, and Web of Science. The investigated features are the intended scenario, type of actuation, supported degrees of freedom, low-level control, high-level control with a focus on intention detection, technology readiness level, and type of experiments conducted to evaluate the device. Results: A total of 105 articles were collected, describing 69 different devices. Devices were grouped according to their actuation type. More than 80% of devices are meant either for rehabilitation, assistance, or both. The most exploited actuation types are pneumatic (52%) and DC motors with cable transmission (29%). Most devices actuate 1 (56%) or 2 (28%) degrees of freedom, and the most targeted joints are the elbow and the shoulder. Intention detection strategies are implemented in 33% of the suits and include the use of switches and buttons, IMUs, stretch and bending sensors, EMG and EEG measurements. Most devices (75%) score a technology readiness level of 4 or 5. Conclusion: Although few devices can be considered ready to reach the market, exosuits show very high potential for the assistance of daily activities. Clinical trials exploiting shared evaluation metrics are needed to assess the effectiveness of upper limb exosuits on target users

Muscle Coordination Contributes to Function after Stroke; Proprioception Contributes to Control of Posture, Movement

More than half of stroke survivors experience persistent upper extremity motor impairments that can negatively impact quality of life and independence. Effective use of the upper extremity requires coordination of agonist/antagonist muscle pairs, as well as coordination of multiple control actions for stabilizing and moving the arm. In this dissertation, I present three studies in which I recorded isometric torque production, single joint movement and stabilization, and clinical measures of function and impairments after stroke to evaluate the extent to which changes in coordination of agonist/antagonist muscles and of sequential control actions contribute to deficits after stroke. In Aim 1, I quantified the extent to which stroke-related deficits in the coordination of agonist/antagonist muscle pairs degraded the ability to generate, maintain, and relax cued torques about the elbow. Participants who survived stroke (SP) and neurologically intact participants (NI) performed pursuit tracking of step-changes in isomeric torque targets to investigate coordination of activation magnitude in elbow agonist/antagonist muscle pairs. SP had marked hypertonia of the primary flexor muscles, which led to increased compensatory activity in the primary extensor muscles. These stroke-related deficits of muscle coordination degraded ability to generate, maintain, and relax cued torque production. In Aim 2, SP and NI performed sequential combinations of elbow stabilization and movements to investigate impairments in execution and coordination of these fundamental control actions. Impaired proprioception in SP was associated with increased impairments in stabilizing the arm against a perturbation compared with SP with intact proprioception. Surprisingly, SP with intact proprioception had greater impairments when moving than did SP with impaired proprioception. These results support the supposition that deficits of somatosensation can differentially impact neural control of limb stabilization and movement. Aim 3 used correlation and forward regression to compare deficits of muscle coordination (Aim 1) and control (Aim 2) to one another in order to quantify the extent to which each could explain deficits of motor function after stroke. Taken together, the three studies revealed that stroke-related deficits in coordination timing and magnitude of muscle activation impact clinically-measured function, and that somatosensory deficits can differentially impair neuromotor stabilization and movement control

Design and Development of a Low Cost Platform to Facilitate Post-Stroke Rehabilitation of the Elbow/Shoulder Region

For post-stroke rehabilitation of the upper limbs, increased amounts of therapy are directly related to improved rehabilitation outcomes. As such, a low cost therapy platform is proposed suitable for facilitating active therapy and administering activeassist therapy to the shoulder/elbow region of the upper limbs of individuals post-stroke in a local clinic or domestic setting. Enabling a person to undergo intensive rehabilitation therapy outside of a rehabilitation hospital setting permits the amount of therapy administered to be maximised. While studies have shown that technological approaches to post-stroke rehabilitation do not produce better outcomes than equal amounts of traditional therapy in a rehabilitation hospital setting, a technological approach has the potential to have significant benefits when that therapy is being undertaken in a local clinic or domestic setting, where the individual undergoing therapy is relatively unsupervised. These benefits largely relate to a technological approach being more motivational for the person than an equivalent manual approach. However, for such an approach to be economically viable, effective, low cost devices are required. This document presents and critically discusses the design of this proposed low cost therapy platform along with possible routes for its further development

Motor control-based assessment of therapy effects in individuals post-stroke: implications for prediction of response and subject-specific modifications

Producing a coordinated motion such as walking is, at its root, the result of healthy communication pathways between the central nervous system and the musculoskeletal system. The central nervous system produces an electrical signal responsible for the excitation of a muscle, and the musculoskeletal system contains the necessary equipment for producing a movement-driving force to achieve a desired motion. Motor control refers to the ability an individual has to produce a desired motion, and the complexity of motor control is a mathematical concept stemming from how the electrical signals from the central nervous system translate to muscle activations. Exercising a high-level complexity of motor control is critical to producing a smooth motion. However, the occurrence of a sudden, detrimental neurological event like a stroke damages these connecting pathways between these two systems, and the result is a motion that is uncoordinated and energy-inefficient due to diminished motor control complexity. Stroke is a leading cause of disability with nearly 800,000 stroke victims each year in the U.S. alone, amounting to an estimated cost of $45.5B. Impaired mobility following a stroke is a widespread effect, with more than half of survivors over the age of 65 affected in this way, and up to 80% of survivors at some point experiencing hemiparesis during post-stroke recovery. As such, given the importance of independent mobility for quality of life, improving gait mechanics and mobility of stroke survivors has been the goal of rehabilitation efforts for decades. In this work, we mold together the forefronts of statistics and computational physics-based modeling to obtain insight and information about post-stroke hemiparetic gait mechanics and what drives them that would otherwise be unavailable. We expand upon previous work to quantify motor control complexity as it relates to the health of the neuromuscular system and analyze the effect of a specific therapy on motor control of individuals post-stroke. Secondly, we aim to develop a predictive model to conclude whether an individual will respond to the therapy based on kinematic and dynamic features from pre-therapy recordings. Lastly, we will determine how to individually tailor this therapy in order to achieve maximum improvement in motor control complexity in order to improve gait mechanics in individuals post-stroke

Fifteen years of wireless sensors for balance assessment in neurological disorders

Balance impairment is a major mechanism behind falling along with environmental hazards. Under physiological conditions, ageing leads to a progressive decline in balance control per se. Moreover, various neurological disorders further increase the risk of falls by deteriorating specific nervous system functions contributing to balance. Over the last 15 years, significant advancements in technology have provided wearable solutions for balance evaluation and the management of postural instability in patients with neurological disorders. This narrative review aims to address the topic of balance and wireless sensors in several neurological disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, stroke, and other neurodegenerative and acute clinical syndromes. The review discusses the physiological and pathophysiological bases of balance in neurological disorders as well as the traditional and innovative instruments currently available for balance assessment. The technical and clinical perspectives of wearable technologies, as well as current challenges in the field of teleneurology, are also examined

A portable robotic rehabilitation system towards improving impaired function of the hand due to stroke

Background: Stroke is the leading cause of adult disability with 70 to 85% of initial strokes resulting in hemiparesis. Physical imparity as a result of stroke tends to be severe and majority of impairments are upper limb-related. Impairment is usually accompanied by long term functional loss which requires dedicated post-stroke rehabilitation to regain motor function. The incidence of stroke is increasing rapidly while there remains a shortage of therapists to provide sufficient rehabilitation. There is therefore a high demand for therapists to attend to the rising number of stroke survivors. Robot-aided therapy has emerged as a beneficial tool for providing continuous rehabilitation of the upper limb and is widely being implemented. With this technology, there is great potential to reduce the ill-effects brought about by the low therapist-patient ratio which has hindered sufficient rehabilitation and consequently the effective recovery of motor function among stroke survivors. Hypothesis: The use of a portable robotic rehabilitation system, as a complementary tool, in hand therapy, would promote continuous rehabilitation by encouraging repetition of task oriented exercises which would enhance motor function of an impaired hand. Task-oriented writing practice would potentially improve hand coordination and result in better accuracy while repetitive training would potentially increase hand motor strength. Objectives: 1.To design and manufacture a portable robotic rehabilitation system. 2. To test the performance and usability of the system. Methods: The system was manufactured and its performance tested in a pilot pre-clinical trial involving three participants. The system's ease of use was assessed using a standardised usability scale. Writing accuracy and hand motor strength were also assessed and the results analysed at the end of the study. Results: The average overall score of usability for the rehabilitation system was a few points higher than the average score. The users of the system also experienced increased motivation whilst performing the repetitive and task oriented exercises. There was an improvement in the completion time of the writing accuracy test and the tasks of the trace sample test. The variation in grip strength of the non-dominant hand during the rehabilitation period was small for each of the participants. Conclusion: The rehabilitation system motivated its users to repetitively perform rehabilitative training which may have improved writing accuracy