Impairments in Cognitive Control Using a Reverse Visually Guided Reaching Task Following Stroke.

BACKGROUND: Cognitive and motor function must work together quickly and seamlessly to allow us to interact with a complex world, but their integration is difficult to assess directly. Interactive technology provides opportunities to assess motor actions requiring cognitive control. OBJECTIVE: To adapt a reverse reaching task to an interactive robotic platform to quantify impairments in cognitive-motor integration following stroke. METHODS: Participants with subacute stroke (N=59) performed two tasks using the Kinarm: Reverse Visually Guided Reaching (RVGR) and Visually Guided Reaching (VGR). Tasks required subjects move a cursor "quickly and accurately" to virtual targets. In RVGR, cursor motion was reversed compared to finger motion (i.e., hand moves left, cursor moves right). Task parameters and Task Scores were calculated based on models developed from healthy controls, and accounted for the influence of age, sex, and handedness. RESULTS: Many stroke participants (86%) were impaired in RVGR with their affected arm (Task Score > 95% of controls). The most common impairment was increased movement time. Seventy-three percent were also impaired with their less affected arm. The most common impairment was larger initial direction angles of reach. Impairments in RVGR improved over time, but 71% of participants tested longitudinally were still impaired with the affected arm ∼6 months post-stroke. Importantly, although 57% were impaired with the less affected arm at 6 months, these individuals were not impaired in VGR. CONCLUSIONS: Individuals with stroke were impaired in a reverse reaching task but many did not show similar impairments in a standard reaching task, highlighting selective impairment in cognitive-motor integration.

A postural unloading task to assess fast corrective responses in the upper limb following stroke.

BACKGROUND: Robotic technologies to measure human behavior are emerging as a new approach to assess brain function. Recently, we developed a robot-based postural Load Task to assess corrective responses to mechanical disturbances to the arm and found impairments in many participants with stroke compared to a healthy cohort (Bourke et al, J NeuroEngineering Rehabil 12: 7, 2015). However, a striking feature was the large range and skewed distribution of healthy performance. This likely reflects the use of different strategies across the healthy control sample, making it difficult to identify impairments. Here, we developed an intuitive "Unload Task". We hypothesized this task would reduce healthy performance variability and improve the detection of impairment following stroke. METHODS: Performance on the Load and Unload Task in the KINARM exoskeleton robot was directly compared for healthy control (n = 107) and stroke (n = 31) participants. The goal was to keep a cursor representing the hand inside a virtual target and return "quickly and accurately" if the robot applied (or removed) an unexpected load to the arm (0.5-1.5 Nm). Several kinematic parameters quantified performance. Impairment was defined as performance outside the 95% of controls (corrected for age, sex and handedness). Task Scores were calculated using standardized parameter scores reflecting overall task performance. RESULTS: The distribution of healthy control performance was smaller and less skewed for the Unload Task compared to the Load Task. Fewer task outliers (outside 99.9 percentile for controls) were removed from the Unload Task (3.7%) compared to the Load Task (7.4%) when developing normative models of performance. Critically, more participants with stroke failed the Unload Task based on Task Score with their affected arm (68%) compared to the Load Task (23%). More impairments were found at the parameter level for the Unload (median = 52%) compared to Load Task (median = 29%). CONCLUSIONS: The Unload Task provides an improved approach to assess fast corrective responses of the arm. We found that corrective responses are impaired in persons living with stroke, often equally in both arms. Impairments in generating rapid motor corrections may place individuals at greater risk of falls when they move and interact in the environment.

A robot-based behavioural task to quantify impairments in rapid motor decisions and actions after stroke.

BACKGROUND: Stroke can affect our ability to perform daily activities, although it can be difficult to identify the underlying functional impairment(s). Recent theories highlight the importance of sensory feedback in selecting future motor actions. This selection process can involve multiple processes to achieve a behavioural goal, including selective attention, feature/object recognition, and movement inhibition. These functions are often impaired after stroke, but existing clinical measures tend to explore these processes in isolation and without time constraints. We sought to characterize patterns of post-stroke impairments in a dynamic situation where individuals must identify and select spatial targets rapidly in a motor task engaging both arms. Impairments in generating rapid motor decisions and actions could guide functional rehabilitation targets, and identify potential of individuals to perform daily activities such as driving. METHODS: Subjects were assessed in a robotic exoskeleton. Subjects used virtual paddles attached to their hands to hit away 200 virtual target objects falling towards them while avoiding 100 virtual distractors. The inclusion of distractor objects required subjects to rapidly assess objects located across the workspace and make motor decisions about which objects to hit. RESULTS: As many as 78 % of the 157 subjects with subacute stroke had impairments in individual global, spatial, temporal, or hand-specific task parameters relative to the 95 % performance bounds for 309 non-disabled control subjects. Subjects with stroke and neglect (Behavioural Inattention Test score <130; n = 28) were more often impaired in task parameters than other subjects with stroke. Approximately half of subjects with stroke hit proportionally more distractor objects than 95 % of controls, suggesting they had difficulty in attending to and selecting appropriate objects. This impairment was observed for affected and unaffected limbs including some whose motor performance was comparable to controls. The proportion of distractors hit also significantly correlated with the Montreal Cognitive Assessment scores for subjects with stroke (r s < = - 0.48, P < 10-9). CONCLUSIONS: A simple robot-based task identified that many subjects with stroke have impairments in the rapid selection and generation of motor responses to task specific spatial goals in the workspace.

Impaired corrective responses to postural perturbations of the arm in individuals with subacute stroke.

BACKGROUND: Stroke is known to alter muscle stretch responses following a perturbation, but little is known about the behavioural consequences of these altered feedback responses. Characterizing impairments in people with stroke in their interactions with the external environment may lead to better long term outcomes. This information can inform therapists about rehabilitation targets and help subjects with stroke avoid injury when moving in the world. METHODS: In this study, we developed a postural perturbation task to quantity upper limb function of subjects with subacute stroke (n = 38) and non-disabled controls (n = 74) to make rapid corrective responses with the arm. Subjects were instructed to maintain their hand at a target before and after a mechanical load was applied to the limb. Visual feedback of the hand was removed for half of the trials at perturbation onset. A number of parameters quantified subject performance, and impairment in performance was defined as outside the 95th percentile performance of control subjects. RESULTS: Individual subjects with stroke showed increased postural instability (44%), delayed motor responses (79%), delayed returns towards the spatial target (79%), and greater endpoint errors (74%). Several subjects also showed impairments in the temporal coordination of the elbow and shoulder joints when responding to the perturbation (47%). Interestingly, impairments in task parameters were often found for both arms of individual subjects with stroke (up to 58% for return time). Visual feedback did not improve performance on task parameters except for decreasing endpoint error for all subjects. Significant correlations between task performance and clinical measures were dependent on the arm assessed. CONCLUSIONS: This study used a simple postural perturbation task to highlight that subjects with stroke commonly have difficulties responding to mechanical disturbances that may have important implications for their ability to perform daily activities.

A robotic object hitting task to quantify sensorimotor impairments in participants with stroke.

BACKGROUND: Existing clinical scores of upper limb function often use observer-based ordinal scales that are subjective and commonly have floor and ceiling effects. The purpose of the present study was to develop an upper limb motor task to assess objectively the ability of participants to select and engage motor actions with both hands. METHODS: A bilateral robotic system was used to quantify upper limb sensorimotor function of participants with stroke. Participants performed an object hit task that required them to hit virtual balls moving towards them in the workspace with virtual paddles attached to each hand. Task difficulty was initially low, but increased with time by increasing the speed and number of balls in the workspace. Data were collected from 262 control participants and 154 participants with recent stroke. RESULTS: Control participants hit ~60 to 90% of the 300 balls with relatively symmetric performance for the two arms. Participants with recent stroke performed the task with most participants hitting fewer balls than 95% of healthy controls (67% of right-affected and 87% of left-affected strokes). Additionally, nearly all participants (97%) identified with visuospatial neglect hit fewer balls than healthy controls. More detailed analyses demonstrated that most participants with stroke displayed asymmetric performance between their affected and non-affected limbs with regards to number of balls hit, workspace area covered by the limb and hand speed. Inter-rater reliability of task parameters was high with half of the correlations above 0.90. Significant correlations were observed between many of the task parameters and the Functional Independence Measure and/or the Behavioural Inattention Test. CONCLUSIONS: As this object hit task requires just over two minutes to complete, it provides an objective and easy approach to quantify upper limb motor function and visuospatial skills following stroke.

The independence of deficits in position sense and visually guided reaching following stroke.

BACKGROUND: Several studies have found correlations between proprioception and visuomotor function during stroke recovery, however two more recent studies have found no correlation. Unfortunately, most of the studies to date have been conducted with clinical assessments of sensation that are observer-based and have poor reliability. We have recently developed new tests to assess position sense and motor function using robotic technology. The present study was conducted to reassess the relationship between position sense and upper limb movement following stroke. METHODS: We assessed position sense and motor performance of 100 inpatient stroke rehabilitation subjects and 231 non-disabled controls. All subjects completed quantitative assessments of position sense (arm-position matching task) and motor performance (visually-guided reaching task) using the KINARM robotic device. Subjects also completed clinical assessments including handedness, vision, Purdue Pegboard, Chedoke-McMaster Stroke Assessment-Impairment Inventory and Functional Independence Measure (FIM). Neuroimaging documented lesion localization. Fisher's exact probability tests were used to determine the relationship between performances on the arm-position matching and visually-guided reaching task. Pearson's correlations were conducted to determine the relationship between robotically measured parameters and clinical assessments. RESULTS: Performance by individual subjects on the matching and reaching tasks was statistically independent (Fisher's test, P<0.01). However, performance on the matching and reaching tasks both exhibited relationships with abilities in daily activities as measured by the FIM. Performance on the reaching task also displayed strong relationships with other clinical measures of motor impairment. CONCLUSIONS: Our data support the concept that position sense deficits are functionally relevant and point to the importance of assessing proprioceptive and motor impairments independently when planning treatment strategies.

Assessment of upper-limb sensorimotor function of subacute stroke patients using visually guided reaching.

OBJECTIVE: Using robotic technology, we examined the ability of a visually guided reaching task to assess the sensorimotor function of patients with stroke. METHODS: Ninety-one healthy participants and 52 with subacute stroke of mild to moderate severity (26 with left- and 26 with right-affected body sides) performed an unassisted reaching task using the KINARM robot. Each participant was assessed using 12 movement parameters that were grouped into 5 attributes of sensorimotor control. RESULTS: A number of movement parameters individually identified a large number of stroke participants as being different from 95% of the controls-most notably initial direction error, which identified 81% of left-affected patients. We also found interlimb differences in performance between the arms of those with stroke compared with controls. For example, whereas only 31% of left-affected participants showed differences in reaction time with their affected arm, 54% showed abnormal interlimb differences in reaction time. Good interrater reliability (r > 0.7) was observed for 9 of the 12 movement parameters. Finally, many stroke patients deemed impaired on the reaching task had been scored 6 or less on the arm portion of the Chedoke-McMaster Stroke Assessment Scale, but some who scored a normal 7 were also deemed impaired in reaching. CONCLUSIONS: Robotic technology using a visually guided reaching task can provide reliable information with greater sensitivity about a patient's sensorimotor impairments following stroke than a standard clinical assessment scale.

Quantitative assessment of limb position sense following stroke.

BACKGROUND: Impairment of position sense of the upper extremity (UE) may impede activities of daily living and limit motor gains after stroke. Most clinical assessments of position sense rely on categorical or ordinal ratings by clinicians that lack sensitivity to change or the ability to discriminate subtle deficits. OBJECTIVE: Use robotic technology to develop a reliable, quantitative technique with a continuous scale to assess UE position sense following stroke. METHODS: Forty-five patients recruited from an inpatient stroke rehabilitation service and 65 age-matched healthy controls performed an arm position matching task. Each UE was fitted in the exoskeleton of a KINARM device. One UE was passively placed in one of 9 positions, and the subject was told to match his or her position with the other UE. Patients were compared with statistical distributions of control data to identify those with deficits in UE position sense. Test-retest sessions using 2 raters established interrater reliability. RESULTS: Two thirds of left hemiparetic and one third of right hemiparetic patients had deficits in limb position sense. Left-affected stroke subjects demonstrated significantly more trial-to-trial variability than right-affected or control subjects. The robotic assessment technique demonstrated good interrater reliability but limited agreement with the clinical thumb localizing test. CONCLUSIONS: Robotic technology can provide a reliable quantitative means to assess deficits in limb position sense following stroke.

A comparison of studies on the quality of life of primary caregivers of stroke survivors: a systematic review of the literature.

BACKGROUND AND PURPOSE: Few studies have been conducted on the quality of life (QOL) of primary caregivers of stroke survivors (with and without aphasia), with little consistency in the methods of evaluation. The purpose of this systematic review of the literature was to determine the appropriateness of study designs and instruments used to assess QOL in caregivers of stroke survivors. METHOD: A comprehensive literature review was conducted to identify peer-reviewed articles of caregiver's QOL where CINAHL, MEDLINE, and PsycINFO databases were searched. RESULTS: Nine studies that met the inclusion criteria used different QOL instruments and study designs. None of the instruments were specific to caregivers of stroke survivors. CONCLUSION: Future studies are warranted to assess the quality of life of caregivers of stroke survivors with and without aphasia.

Toward benchmarks for stroke rehabilitation in Ontario, Canada.

OBJECTIVE: Canadian benchmarking data do not exist for stroke rehabilitation services. This study used the FIM-function-related group (FIM-FRG) classification system to group patients and to describe the outcomes within each group. The intent was to begin to develop benchmarks for persons recovering from stroke in Canadian rehabilitation facilities. DESIGN: 561 patients were stratified into the nine categories of the FIM-FRG system. Length of stay (LOS), total FIM gain, total FIM at discharge, and discharge location were described for each category. RESULTS: Mean waiting time to rehabilitation admission was 29.7 days. Mean LOS was 49.2 days. Mean admission and discharge total FIM ratings were 78.1 and 103.1, respectively. FIM gain ranged from 8 to 37. Seventeen percent of patients were discharged to nursing homes, with rates ranging from a low of 0% (FRG 8 and 9) to a high of 60% (FRG 2). CONCLUSIONS: For the nine FIM-FRG groups, LOS was considerably longer in the Canadian facility than in the United States, and total FIM score at discharge was higher in Canada. This is likely related to differences in the healthcare systems of the two countries and confirms the need to develop benchmarks based on Canadian data.

First Clinical Experience with BION Implants for Therapeutic Electrical Stimulation.

The objective of this study was to assess the usability and safety of BION injectable neuromuscular microstimulators for therapeutic electrical stimulation (TES) to treat two conditions involving disuse atrophy: poststroke shoulder subluxation in hemiplegic subjects and knee osteoarthritis. Clinicians were provided with PC-based software to track implants and to design the exercise programs. Subjects self-administered TES (3 sessions/day, 10-30 min/session) for 6 or 12 weeks. Outcome measures included subluxation for the shoulder study and knee function and pain for the osteoarthritis study. All subjects were comfortable with the BION equipment and therapy; eight of 10 experimental subjects elected to continue treatment after the study period. Shoulder subluxation was reduced by 55% ± 54%; knee function was enhanced by 65% ± 24%; and knee pain decreased by 78% ± 18%. The devices did not migrate and did not cause inflammation or pain. Thresholds were stable over time. We conclude that the use of BION implants to exercise atrophic muscles was well-accepted and provided effective rehabilitation in these two clinical conditions.