Evaluation of upper extremity robot-assistances in subacute and chronic stroke subjects

<p>Abstract</p> <p>Background</p> <p>Robotic systems are becoming increasingly common in upper extremity stroke rehabilitation. Recent studies have already shown that the use of rehabilitation robots can improve recovery. This paper evaluates the effect of different modes of robot-assistances in a complex virtual environment on the subjects' ability to complete the task as well as on various haptic parameters arising from the human-robot interaction.</p> <p>Methods</p> <p>The MIMICS multimodal system that includes the haptic robot HapticMaster and a dynamic virtual environment is used. The goal of the task is to catch a ball that rolls down a sloped table and place it in a basket above the table. Our study examines the influence of catching assistance, pick-and-place movement assistance and grasping assistance on the catching efficiency, placing efficiency and on movement-dependant parameters: mean reaching forces, deviation error, mechanical work and correlation between the grasping force and the load force.</p> <p>Results</p> <p>The results with groups of subjects (23 subacute hemiparetic subjects, 10 chronic hemiparetic subjects and 23 control subjects) showed that the assistance raises the catching efficiency and pick-and-place efficiency. The pick-and-place movement assistance greatly limits the movements of the subject and results in decreased work toward the basket. The correlation between the load force and the grasping force exists in a certain phase of the movement. The results also showed that the stroke subjects without assistance and the control subjects performed similarly.</p> <p>Conclusions</p> <p>The robot-assistances used in the study were found to be a possible way to raise the catching efficiency and efficiency of the pick-and-place movements in subacute and chronic subjects. The observed movement parameters showed that robot-assistances we used for our virtual task should be improved to maximize physical activity.</p

An adaptive 4-week robotic training program of the upper limb for persons with multiple sclerosis

It is suggested that repetitive movements can initiate motor recovery and improve motor learning in populations with neurological impairments and this process can be optimized with robotic devices. The repetitive, reproducible and high dose motor movements that can be delivered by robotics have shown positive results in functional outcomes in stroke patients. However, there is little research on robotic neurorehabilitation for persons with multiple sclerosis (PwMS), more specifically there is lack of literature with focus on the upper extremity. Therefore, the purpose of this work was to use a robotic device to implement an adaptive training program of the forearm and wrist for PwMS. This approach is unique, as it incorporates real time learning from the robotic device to alter the level of assistance/resistance to the individual. This methodology is novel and could prove to be an effective way to properly individualize the therapy process with correct dosage and prescription. 7 individuals with varying levels of MS, placed their most affected limb (forearm) on a robotic device (Wristbot), grasped the handle, and using real-time visual feedback, traced a Lissajous curve allowing the wrist to move in flexion/extension, radial/ulnar directions. Robotic training occurred 3 times per week for 4 consecutive weeks and included 40 minutes of work. Robotic software was adaptive and updated every 3 laps to evaluate the average kinematic performance which modified the robotic assistance/resistance. Outcome measures were taken pre and post intervention. Improvements in performance were quantified by average tracking and figural error, which was significantly reduced from pre – post intervention. Isometric wrist strength and grip force endurance also significantly improved from pre to post intervention. However, maximum grip force, joint position matching, 9-hole peg test, and patient-rated wrist evaluation did not show any significant improvements. To our knowledge, this study was the first adaptive and individualized robotic rehabilitation program providing two opposing forces to the hand/wrist for PwMS. Results of this 4-week training intervention, provide a proof-of-concept that motor control and muscular strength can be improved by this rehabilitation modality. This work acts as a stepping-stone into future investigations of robotic rehabilitation for an MS population

A haptic robot reveals the adaptation capability of individuals with Multiple Sclerosis

A prerequisite for rehabilitation is that patients preserve their ability to adapt to novel dynamic environments, an ability that has been associated with the cerebellar system. In this study, we use a robot manipulandum to assess the ability of multiple sclerosis (MS) sub- jects in the early phase of the disease to adapt to a speed-dependent force field. Their performance is compared with an equal number of age-matched controls. We found that MS subjects display subtle in- coordination problems but do not significantly differ from controls in their ability to adapt to the force field. These findings are discussed in terms of the possible benefits that MS subjects might receive from robot-assisted therapy that is specifically aimed at impaired visuomo- tor coordination

The Influence of Dopamine Replacement on Movement Impairments During Bimanual Coordination in Parkinson’s Disease (PD)

The purpose of the current thesis was to investigate the influence of dopamine replacement on performance during bimanual coordination in individuals with Parkinson’s disease (PD) There has been conflicting research on the cause of movement impairments such as coordination deficits, slowed switching and upper limb freezing that occur during coordinated movements It is unclear whether decreased function of the dopaminergic system after withdrawal from dopamine replacement is responsible for these deficits Healthy age-matched control participants were compared to PD participants in two experiments to determine the movement impairments that occurred during three-dimensional wrist flexion-extension bimanual coordination as a result of PD. In addition, individuals with PD were compared without (‘off’) and with (‘on’) dopamine replacement in both experiments to determine whether modulation of the dopaminergic system influenced coordinated movements. In Experiment 1, continuous bimanual coordination was performed in m-phase (simultaneous wrist flexion and extension) and anti-phase (flexion of one wrist while extending other wrist) with movements externally paced with increasing across seven cycle frequencies (0.75 to 2 Hz). Visual feedback was also manipulated in one of three sensory conditions no vision, normal vision or augmented vision. Visual feedback, phase and cycle frequency manipulation was performed to determine whether other deficits (e.g. sensory and/or attentional deficits) may influence coordinated movements Despite reduced amplitude of movements in both limbs of individuals with PD (PD ‘off’), coordination deficits were not observed in PD compared to healthy control participants. In addition, there was an increased occurrence of upper limb freezing (ULF) when cycle frequency demand was greater Dopamine replacement did increase the amplitude of movements in individuals with PD but did not influence coordination performance or the occurrence of ULF. In Experiment 2, coordinated movements were initiated in either m-phase or antiphase and participants were required to voluntarily switch to the other phase pattern when an auditory cue was presented Trials were performed at one of two cycle frequencies (1 or 2 Hz) and one of two sensory conditions (no vision or normal vision) to determine whether other deficits (e.g. sensory and/or attentional deficits) may influence coordinated movement. In addition, a separate block of trials were performed in anti-phase coordination with an auditory cue that did not require a switch Non-switching trials were included to investigate whether the presence of a distracting cue could evoke ULF comparable to when switching between movements was required PD ‘off’ participants demonstrated slower switching, more delayed responses and deficits in coordination performance when compared to healthy control participants. The increased demand of cycle frequency particularly when initiating anti-phase coordination, after voluntary switching and with the presence of the auditory cue without switching contributed to a large occurrence of ULF in individuals with PD. Dopamine replacement improved the ability to switch between phase patterns but had no overall influence on coordination performance or the occurrence of ULF. Overall, the results of the current thesis demonstrated that dopamine replacement can improve motor symptoms during coordinated movements (e g hypometna and bradykinesia) but does not contribute to coordination performance or ULF in individuals with PD. As a consequence, it was concluded that coordination deficits and ULF are not caused by the dysfunctional dopaminergic system but rather associated to secondary impairment caused by PD. The movement impairments caused by secondary dysfunction of PD were proposed to be associated with increased attentional demands and possible executive dysfunction related to fronto-stnatal pathways that cannot be modulated by dopamine replacement. Thus, treatment of complex movement impairments such as coordination deficits and ULF may benefit from rehabilitation or non-dopamine therapies that focus on the global dysfunction caused by PD

Investigating sensory-motor interactions to shape rehabilitation

Over the last decades, robotic devices for neurorehabilitation have been developed with the aim of providing better and faster improvement of motor performance. These devices are being used to help patients repeat movements and (re)learn different dynamic tasks. Over the years, these devices have become bigger and more complex, so as to provide the end user with a more realistic and sophisticated stimuli while still allowing the experimenter to have control over the interaction forces that can potentially shape the motor behaviour. However, experimental results have shown no clear advantage of these complex devices over simpler versions. In this context, this thesis investigates sensory-motor processes of human interaction, which can help us understand the main issues for rehabilitation devices and how to overcome the limitations of simple devices to train particular motor behaviours. Conventional neurorehabilitation of motor function relies on haptic interaction between the patient and physiotherapist. However, how humans deal with human-human interactions is largely unknown, and has been little studied. In this regard, experiments of the first section of the thesis investigate the mechanisms of interaction during human-human collaborative tasks. It goes from identifying the different strategies that dyads can take to proposing methods to measure and understand redundancy and synchrony in haptic interactions. It also shows that one can shape the interaction between partners by modifying only the visual information provided to each agent. Learning a novel skill requires integration of different sensory modalities, in particular vision and proprioception. Hence, one can expect that learning will depend on the mechanical characteristics of the device. For instance, a device with limited degrees of freedom will reduce the amount of information about the environment, modify the dynamics of the task and prevent certain error-based corrections. To investigate this, the second section of the thesis examines whether the lack of proprioceptive feedback that is created due to mechanical constraints or haptic guidance can be substituted with visual information. Psychophysical experiments with healthy subjects and some preliminary experiments with stroke patients presented in this thesis support the idea that by incorporating task-relevant visual feedback into simple devices, one could deliver effective neurorehabilitation protocols. The contributions of the thesis are not limited to the role of visual feedback to shape motor behaviour, but also advance our understanding on the mechanisms of learning and human-human interaction