Predictors of Arm Nonuse in Chronic Stroke: A Preliminary Investigation

Reaching the cognitive-motor interface: effects of cognitive load on arm choice and motor performance after stroke

A vexing characteristic of motor disability after stroke is that many individuals fail to use their affected arm effectively despite having the capacity to do so, a phenomenon termed arm nonuse. Based on the hypothesis that nonuse is influenced by the competing cognitive demands of many daily activities, we examined the effects of cognitive load on arm choice and motor performance in individuals with stroke using a novel virtual reality paradigm that mimics the demands of real-life visual search, object selection, and reaching to targets. Twenty individuals with single left or right hemispheric chronic stroke (11 left cerebrovascular accident; 9 right cerebrovascular accident) and 10 age-matched neurotypical participants completed the Virtual Reality Arm Choice task, in which they reached for target objects in an array under varied cognitive demand. To manipulate cognitive demand, we varied the semantic similarity of objects in the reaching space and the presence or absence of a secondary task. The results showed reduced use of the paretic arm under increased demand. Under cognitive load, participants with stroke also showed slower reach initiation, slower movements, increased reach curvature, and increased performance differences between the paretic and non-paretic arms. The arm choice of neurotypical individuals was also modulated under cognitive load. These data indicate that cognitive factors influence arm choice and motor performance in naturalistic reaching tasks in individuals with chronic stroke. Performance decrements under cognitive load may in turn influence reduced paretic arm use during daily activities.

The feasibility of the adapted H-GRASP program for perceived and actual daily-life upper limb activity in the chronic phase post-stroke

PURPOSE

Assessing feasibility and initial impact of the Home-Graded Repetitive Arm Supplementary Program combined with in-home accelerometer-based feedback (AH-GRASP) on perceived and actual daily-life upper limb (UL) activity in stroke survivors during the chronic phase with good UL motor function but low perceived daily-life activity.

MATERIAL AND METHODS

A 4-week intervention program (4 contact hours, 48 h self-practice) encompassing task-oriented training, behavioral techniques, phone-based support, monitoring, and weekly feedback sessions using wrist-worn accelerometery was implemented using a pre-post double baseline repeated measures design. Feasibility, clinical assessments, patient-reported outcomes, and accelerometer data were investigated.

RESULTS

Of the 34 individuals approached, nineteen were included (recruitment rate 56%). Two dropped out, one due to increased UL pain (retention rate 89%). Seven (41%) achieved the prescribed exercise target (120 min/day, six days/week). Positive patient experiences and improvements in UL capacity, self-efficacy, and contribution of the affected UL to overall activity (p < 0.05, small to large effect sizes) were observed. Additionally, seven participants (41%) surpassed the minimal clinically important difference in perceived UL activity.

CONCLUSIONS

A home-based UL exercise program with accelerometer-based feedback holds promise for enhancing perceived and actual daily-life UL activity for our subgroup of chronic stroke survivors.

Diminished sense of agency inhibits paretic upper-limb use in patients with post-stroke motor deficits

Post-stroke motor deficits often disrupt the voluntary control of body movements, leading to abnormal feelings. Among these, alterations in the sense of agency (SoA), the feeling of controlling one's movement, are notable because SoA facilitates actions. However, whether patients with more severe motor deficits experience poorer SoA and SoA's clinical impact on motor activity remain unclear. To address these questions, this longitudinal study quantified SoA in 156 post-stroke patients through factor analyses with multiple question items to differentiate SoA from potentially confounding discomfort. Structural equation modeling revealed that SoA decreased significantly with upper-limb motor deficit severity and that reduced SoA correlated significantly with decreased paretic upper-limb use. Notably, this effect persisted after controlling for motor deficit severity, suggesting a direct clinical impact of SoA on motor activity. Further, improvements in SoA were significantly associated with increased upper-limb use in patients with moderate or severe motor deficits, emphasizing the role of SoA in maintaining or increasing paretic upper-limb activity. These findings highlight the importance of rehabilitation treatments that consider patients' subjective experiences, particularly agency attribution.

Chronic stroke survivors underestimate their upper limb motor ability in a simple 2D motor task

BACKGROUND

Stroke survivors can exhibit a mismatch between the actual motor ability of their affected upper limb and how much they use it in daily life. The resulting non-use of the affected upper limb has a negative impact on participation in neurorehabilitation and functional independence. The factors leading to non-use of the affected upper limb are poorly understood. One possibility is that non-use comes about through inappropriately low confidence in their own upper limb motor abilities.

OBJECTIVE

We asked whether chronic stroke survivors underestimate the motor ability of their affected upper limb.

METHODS

20 chronic stroke survivors (Mean FM: 28.2 ± 10.5) completed a 2D reaching task using an exoskeleton robot. Target sizes were individually altered to ensure success rates were similar for both upper limbs. Prior to each reaching movement, participants rated their confidence about successfully hitting the target (estimated upper limb motor ability).

RESULTS

Confidence ratings were significantly lower for the affected upper limb (estimated ability), even though it was equally successful in the reaching task in comparison to the less affected upper limb (actual ability). Furthermore, confidence ratings did not correlate with level of impairment.

CONCLUSIONS

Our results demonstrate that chronic stroke survivors can underestimate the actual motor abilities of their affected upper limb, independent of impairment level. Low confidence in affected upper limb motor abilities should be considered as a therapeutic target to increase the incorporation of the affected upper limb into activities of daily living.

Therapeutic effect of adjuvant therapy added to constraint-induced movement therapy in patients with subacute to chronic stroke: a systematic review and meta-analysis

PURPOSE

This review investigated the effectiveness of adjuvant therapy combined with constraint-induced movement therapy (CIMT) in improving the paretic upper limb functionality in adults with stroke sequelae during the subacute to chronic rehabilitation phase.

MATERIALS AND METHODS

In this systematic review and meta-analysis of randomized controlled trials (RCT), electronic databases, including PubMed, Web of Science, CINAHL, and MEDLINE, were searched. We included RCTs that investigated the outcomes of adjuvant therapy (i.e. other therapies) added to CIMT compared with CIMT alone. Key trial findings were qualitatively synthesized and analyzed. This meta-analysis examined variables, such as mean scores and standard deviations, using the following outcome measures: Fugl-Meyer Assessment (FMA) upper limb items, Action Research Arm Test (ARAT), Amount of Use (AOU) of Motor Activity Log (MAL), and Quality of Movement (QOM) of MAL.

RESULTS

Eighteen eligible RCTs were included in the analysis. Adding CIMT to adjunctive therapy significantly improved FMA compared with CIMT alone (mean difference [MD] 4.02, 95% confidence interval [CI] 2.60-5.44; I2 = 85%; 15 studies; 330 participants). Similarly, the ARAT and MAL-AOU scores improved significantly.

CONCLUSIONS

CIMT combined with several adjunctive therapies effectively improved upper limb function.

Feasibility and efficacy of an early sensory-motor rehabilitation program on hand function in patients with stroke: a pilot, single-subject experimental design

OBJECTIVE

Hand and upper limb functional impairments following stroke lead to limitations in performing activities of daily living. We aimed to investigate feasibility and efficacy of an early sensory-motor rehabilitation program on hand and upper limb function in patients with acute stroke.

DESIGN

A pilot, single-subject experimental, A-B-A study.

SETTING

Stroke unit of an educational hospital and an outpatient occupational therapy clinic.

PARTICIPANTS

A convenience sample including five people with acute stroke.

PROCEDURES

Participants received 3 h of an intensive hand and upper limb sensory and motor rehabilitation program, 5 days per week for 3 months (15-min mental imagery, 15-min action observation, 30-min mirror therapy, 1.5-h constraint-induced movement therapy, and 30-min bilateral arm training). Activities were chosen based on the task-oriented occupational therapy approach.

OUTCOME MEASURES

An assessor blinded to intervention program measured sensory and motor functions using action research arm test, box and block test, Semmes-Weinstein monofilaments, and upper extremity section of Fugl-Meyer assessment.

RESULTS

Assessment data points in intervention and follow-up phases compared to baseline were in higher levels, sloped upwardly, and increased significantly for all participants in all outcome measures.

CONCLUSIONS

The present pilot study showed that a package of nowadays evidence-based rehabilitation methods including mental imagery, action observation, mirror therapy, modified constraint-induced movement therapy, bilateral arm training, and task-oriented occupational therapy approach is able to improve sensory and motor functions of the hand and upper limb in patients with acute stroke.

Wearable Technology to Capture Arm Use of People With Stroke in Home and Community Settings: Feasibility and Early Insights on Motor Performance

OBJECTIVE

The objectives of this study were to establish the short-term feasibility and usability of wrist-worn wearable sensors for capturing the arm and hand activity of people with stroke and to explore the association between factors related to the use of the paretic arm and hand.

METHODS

Thirty people with chronic stroke were monitored with wrist-worn wearable sensors for 12 hours per day for a 7-day period. Participants also completed standardized assessments to capture stroke severity, arm motor impairments, self-perceived arm use, and self-efficacy. The usability of the wearable sensors was assessed using the adapted System Usability Scale and an exit interview. Associations between motor performance and capacity (arm and hand impairments and activity limitations) were assessed using Spearman correlations.

RESULTS

Minimal technical issues or lack of adherence to the wearing schedule occurred, with 87.6% of days procuring valid data from both sensors. The average sensor wear time was 12.6 (standard deviation [SD] = 0.2) hours per day. Three participants experienced discomfort with 1 of the wristbands, and 3 other participants had unrelated adverse events. There were positive self-reported usability scores (mean = 85.4/100) and high user satisfaction. Significant correlations were observed for measures of motor capacity and self-efficacy with paretic arm use in the home and the community (Spearman correlation coefficients = 0.44-0.71).

CONCLUSIONS

This work demonstrates the feasibility and usability of a consumer-grade wearable sensor for capturing paretic arm activity outside the laboratory. It provides early insight into the everyday arm use of people with stroke and related factors, such as motor capacity and self-efficacy.

IMPACT

The integration of wearable technologies into clinical practice offers new possibilities to complement in-person clinical assessments and to better understand how each person is moving outside of therapy and throughout the recovery and reintegration phase. Insight gained from monitoring the arm and hand use of people with stroke in the home and community is the first step toward informing future research with an emphasis on causal mechanisms with clinical relevance.

A metric for characterizing the arm nonuse workspace in poststroke individuals using a robot arm

An overreliance on the less-affected limb for functional tasks at the expense of the paretic limb and in spite of recovered capacity is an often-observed phenomenon in survivors of hemispheric stroke. The difference between capacity for use and actual spontaneous use is referred to as arm nonuse. Obtaining an ecologically valid evaluation of arm nonuse is challenging because it requires the observation of spontaneous arm choice for different tasks, which can easily be influenced by instructions, presumed expectations, and awareness that one is being tested. To better quantify arm nonuse, we developed the bimanual arm reaching test with a robot (BARTR) for quantitatively assessing arm nonuse in chronic stroke survivors. The BARTR is an instrument that uses a robot arm as a means of remote and unbiased data collection of nuanced spatial data for clinical evaluations of arm nonuse. This approach shows promise for determining the efficacy of interventions designed to reduce paretic arm nonuse and enhance functional recovery after stroke. We show that the BARTR satisfies the criteria of an appropriate metric for neurorehabilitative contexts: It is valid, reliable, and simple to use.

Post-stroke deficits in the anticipatory control and bimanual coordination during naturalistic cooperative bimanual action

BACKGROUND

Unilateral stroke leads to asymmetric deficits in movement performance; yet its effects on naturalistic bimanual actions, a key aspect of everyday functions, are understudied. Particularly, how naturalistic bimanual actions that require the two hands to cooperatively interact with each other while manipulating a single common object are planned, executed, and coordinated after stroke is not known. In the present study, we compared the anticipatory planning, execution, and coordination of force between individuals with left and right hemisphere stroke and neurotypical controls in a naturalistic bimanual common-goal task, lifting a box.

METHOD

Thirty-three individuals with chronic stroke (15 LCVA, 18 RCVA) and 8 neurotypical age-matched controls used both hands to lift a box fitted with force transducers under unweighted and weighted conditions. Primary dependent variables included measures of anticipation (peak grip and load force rate), execution (peak grip force, load force), and measures of within-hand (grip-load force coordination) and between-hand coordination (force rate cross-correlations). Primary analyses were performed using linear mixed effects modeling. Exploratory backward stepwise regression examined predictors of individual variability within participants with stroke.

RESULTS

Participants with stroke, particularly the RCVA group, showed impaired scaling of grip and load force rates with the addition of weight, indicating deficits in anticipatory control. While there were no group differences in peak grip force, participants with stroke showed significant impairments in peak load force and in grip-load force coordination with specific deficits in the evolution of load force prior to object lift-off. Finally, there were differences in spatial coordination of load force rates for participants with stroke, and especially the RCVA group, as compared to controls. Unimanual motor performance of the paretic arm and hemisphere of lesion (right hemisphere) were the key predictors of impairments in anticipatory planning of grip force and bimanual coordination among participants with stroke.

CONCLUSIONS

These results suggest that individuals with stroke, particularly those with right hemisphere damage, have impairments in anticipatory planning and interlimb coordination of symmetric cooperative bimanual tasks.

Autonomy support encourages use of more-affected arm post-stroke

BACKGROUND

Autonomy support, which involves providing individuals the ability to control their own behavior, is associated with improved motor control and learning in various populations in clinical and non-clinical settings. This study aimed to investigate whether autonomy support combined with an information technology (IT) device facilitated success in using the more-affected arm during training in individuals with stroke. Consequently, we examined whether increased success influenced the use of the more-affected arm in mild to moderate subacute to chronic stroke survivors.

METHODS

Twenty-six participants with stroke were assigned to the autonomy support or control groups. Over a 5-week period, training and test sessions were conducted using the Individualized Motivation Enhancement System (IMES), a device developed specifically for this study. In the autonomy support group, participants were able to adjust the task difficulty parameter, which controlled the time limit for reaching targets. The control group did not receive this option. The evaluation of the more-affected arm's use, performance, and impairment was conducted through clinical tests and the IMES. These data were then analyzed using mixed-effect models.

RESULTS

In the IMES test, both groups showed a significant improvement in performance (p < 0.0001) after the training period, without any significant intergroup differences (p > 0.05). However only the autonomy support group demonstrated a significant increase in the use of the more-affected arm following the training (p < 0.001). Additionally, during the training period, the autonomy support group showed a significant increase in successful experiences with using the more-affected arm (p < 0.0001), while the control group did not exhibit the same level of improvement (p > 0.05). Also, in the autonomy support group, the increase in the use of the more-affected arm was associated with the increase in the successful experience significantly (p = 0.007).

CONCLUSIONS

Combining autonomy support with an IT device is a practical approach for enhancing performance and promoting the use of the more-affected upper extremity post-stroke. Autonomy support facilitates the successful use of the more-affected arm, thereby increasing awareness of the training goal of maximizing its use.

TRIAL REGISTRATION

The study was registered retrospectively with the Clinical Research Information Service (KCT0008117; January 13, 2023; https://cris.nih.go.kr/cris/search/detailSearch.do/23875 ).

Predicting Arm Nonuse in Individuals with Good Arm Motor Function after Stroke Rehabilitation: A Machine Learning Study

Many stroke survivors demonstrate arm nonuse despite good arm motor function. This retrospective secondary analysis aims to identify predictors of arm nonusers with good arm motor function after stroke rehabilitation. A total of 78 participants were categorized into 2 groups using the Fugl-Meyer Assessment Upper Extremity Scale (FMA-UE) and the Motor Activity Log Amount of Use (MAL-AOU). Group 1 comprised participants with good motor function (FMA-UE ≥ 31) and low daily upper limb use (MAL-AOU ≤ 2.5), and group 2 comprised all other participants. Feature selection analysis was performed on 20 potential predictors to identify the 5 most important predictors for group membership. Predictive models were built with the five most important predictors using four algorithms. The most important predictors were preintervention scores on the FMA-UE, MAL-Quality of Movement, Wolf Motor Function Test-Quality, MAL-AOU, and Stroke Self-Efficacy Questionnaire. Predictive models classified the participants with accuracies ranging from 0.75 to 0.94 and areas under the receiver operating characteristic curve ranging from 0.77 to 0.97. The result indicates that measures of arm motor function, arm use in activities of daily living, and self-efficacy could predict postintervention arm nonuse despite good arm motor function in stroke. These assessments should be prioritized in the evaluation process to facilitate the design of individualized stroke rehabilitation programs to reduce arm nonuse.

Predicting later categories of upper limb activity from earlier clinical assessments following stroke: an exploratory analysis

BACKGROUND

Accelerometers allow for direct measurement of upper limb (UL) activity. Recently, multi-dimensional categories of UL performance have been formed to provide a more complete measure of UL use in daily life. Prediction of motor outcomes after stroke have tremendous clinical utility and a next step is to explore what factors might predict someone's subsequent UL performance category.

PURPOSE

To explore how different machine learning techniques can be used to understand how clinical measures and participant demographics captured early after stroke are associated with the subsequent UL performance categories.

METHODS

This study analyzed data from two time points from a previous cohort (n = 54). Data used was participant characteristics and clinical measures from early after stroke and a previously established category of UL performance at a later post stroke time point. Different machine learning techniques (a single decision tree, bagged trees, and random forests) were used to build predictive models with different input variables. Model performance was quantified with the explanatory power (in-sample accuracy), predictive power (out-of-bag estimate of error), and variable importance.

RESULTS

A total of seven models were built, including one single decision tree, three bagged trees, and three random forests. Measures of UL impairment and capacity were the most important predictors of the subsequent UL performance category, regardless of the machine learning algorithm used. Other non-motor clinical measures emerged as key predictors, while participant demographics predictors (with the exception of age) were generally less important across the models. Models built with the bagging algorithms outperformed the single decision tree for in-sample accuracy (26-30% better classification) but had only modest cross-validation accuracy (48-55% out of bag classification).

CONCLUSIONS

UL clinical measures were the most important predictors of the subsequent UL performance category in this exploratory analysis regardless of the machine learning algorithm used. Interestingly, cognitive and affective measures emerged as important predictors when the number of input variables was expanded. These results reinforce that UL performance, in vivo, is not a simple product of body functions nor the capacity for movement, instead being a complex phenomenon dependent on many physiological and psychological factors. Utilizing machine learning, this exploratory analysis is a productive step toward the prediction of UL performance. Trial registration NA.

Upper extremity self-efficacy correlates with daily hand-use of individuals with high functional capacity post-stroke

PURPOSE

To understand the role of affected upper extremity (UE) self-efficacy for explaining daily-hand-use in individuals post-stroke. Specifically, to describe UE self-efficacy and to assess the associations between UE self-efficacy to UE motor and functional capacity and daily hand-use.

MATERIALS AND METHODS

This cross-sectional study included individuals post-stroke receiving rehabilitation with high UE functional capacity [Action Research Arm Test (ARAT) > 50]. The Rating of Everyday Arm-Use in the Community and Home (REACH) assessed perceived UE daily use and the Confidence in Arm and Hand Movement scale (CAHM) assessed UE self-efficacy. Functional capacity was assessed by the ARAT and the Fugl-Meyer-motor-assessment assessed motor impairment. Correlations between measures were assessed.

RESULTS

Twenty-two individuals, aged 19-80, with high UE functional capacity [median (IQR) ARAT-56.5 (54-57)] and varying UE self-efficacy [median (IQR) CAHM-76.7 (58-84.4)], were included. UE self-efficacy was significantly correlated with the ARAT (r_s = 0.53, p < 0.01) and REACH (r_s = 0.51, p < 0.01) but ARAT was not significantly correlated with REACH.

CONCLUSIONS

UE self-efficacy is correlated with perceived daily hand-use in individuals with high functional capacity. Further research and a deeper understanding of the clinical implications of UE self-efficacy are warranted. UE self-efficacy should perhaps be assessed during rehabilitation. IMPLICATIONS FOR REHABILITATIONIndividuals with stroke with high affected upper extremity functional capacity do not necessarily use this hand for daily living.Upper extremity self-efficacy is correlated with perceived daily hand-use in individuals with high functional capacity; participants with higher upper extremity self-efficacy also reported more daily hand-use.Upper extremity self-efficacy seems to be upper extremity task or situation-specific.Upper extremity self-efficacy should be assessed during rehabilitation and the clinical implications of (low) upper extremity self-efficacy should be further researched.

Virtuous and Vicious Cycles of Arm Use and Function Post-stroke

Large doses of movement practice have been shown to restore upper extremities' motor function in a significant subset of individuals post-stroke. However, such large doses are both difficult to implement in the clinic and highly inefficient. In addition, an important reduction in upper extremity function and use is commonly seen following rehabilitation-induced gains, resulting in "rehabilitation in vain". For those with mild to moderate sensorimotor impairment, the limited spontaneous use of the more affected limb during activities of daily living has been previously proposed to cause a decline of motor function, initiating a vicious cycle of recovery, in which non-use and poor performance reinforce each other. Here, we review computational, experimental, and clinical studies that support the view that if arm use is raised above an effective threshold, one enters a virtuous cycle in which arm use and function can reinforce each other via self-practice in the wild. If not, one enters a vicious cycle of declining arm use and function. In turn, and in line with best practice therapy recommendations, this virtuous/vicious cycle model advocates for a paradigm shift in neurorehabilitation whereby rehabilitation be embedded in activities of daily living such that self-practice with the aid of wearable technology that reminds and motivates can enhance paretic limb use of those who possess adequate residual sensorimotor capacity. Altogether, this model points to a user-centered approach to recovery post-stroke that is tailored to the participant's level of arm use and designed to motivate and engage in self-practice through progressive success in accomplishing meaningful activities in the wild.

Determinants of Different Aspects of Upper-Limb Activity after Stroke

We examined factors associated with different aspects of upper-limb (UL) activity in chronic stroke to better understand and improve UL activity in daily life. Three different aspects of UL activity were represented by four sensor measures: (1) contribution to activity according to activity ratio and magnitude ratio, (2) intensity of activity according to bilateral magnitude, and (3) variability of activity according to variation ratio. We combined data from a Belgian and Danish patient cohort (n = 126) and developed four models to determine associated factors for each sensor measure. Results from standard multiple regression show that motor impairment (Fugl−Meyer assessment) accounted for the largest part of the explained variance in all sensor measures (18−61%), with less motor impairment resulting in higher UL activity values (p < 0.001). Higher activity ratio, magnitude ratio, and variation ratio were further explained by having the dominant hand affected (p < 0.007). Bilateral magnitude had the lowest explained variance (adjusted R2 = 0.376), and higher values were further associated with being young and female. As motor impairment and biological aspects accounted for only one- to two-thirds of the variance in UL activity, rehabilitation including behavioral strategies might be important to increase the different aspects of UL activity.

Hand dominance in the performance and perceptions of virtual reach control

PURPOSE

Efforts to optimize human-computer interactions are becoming increasingly prevalent, especially with virtual reality (VR) rehabilitation paradigms that utilize engaging interfaces. We hypothesized that motor and perceptional behaviors within a virtual environment are modulated uniquely through different modes of control of a hand avatar depending on limb dominance. This study investigated the effects of limb dominance on performance and concurrent changes in perceptions, such as time-based measures for intentional binding, during virtual reach-to-grasp.

METHODS

Participants (n = 16, healthy) controlled a virtual hand through their own hand motions with control adaptations in speed, noise, and automation.

RESULTS

A significant (p < 0.01) positive relationship between performance (reaching pathlength) and binding (time-interval estimation of beep-sound after grasp contact) was observed for the dominant hand. Unique changes in performance (p < 0.0001) and binding (p < 0.0001) were observed depending on handedness and which control mode was applied.

CONCLUSIONS

Developers of VR paradigms should consider limb dominance to optimize settings that facilitate better performance and perceptional engagement. Adapting VR rehabilitation for handedness may particularly benefit unilateral impairments, like hemiparesis or single-limb amputation.

Upper extremity motor abilities and cognitive capability mediate the causal dependency between somatosensory capability and daily function in stroke individuals

Stroke individuals’ daily function has been demonstrated to be influenced by their somatosensory capability, cognitive capability, and upper extremity (UE) motor abilities. However, the structural relationships among these abilities on stroke individuals’ independence in daily function remain unclear. We analyzed the pretest measures of 153 stroke individuals in outpatient rehabilitation settings by structural equation modeling to determine the structural relationship among somatosensory capability, UE muscle strength, UE motor function, and cognitive capability that influences independence in daily function. The standardized results indicated somatosensory capability negatively influenced UE muscle strength, but positively influenced UE muscle strength mediated by UE motor function. UE muscle strength, then, positively influenced individuals’ independence in daily function. On the other hand, somatosensory capability positively influenced cognitive capability, which marginally and positively affected the performance of independence in daily function. To the best of our knowledge, this is the first study to demonstrate the influence of somatosensory capability on the daily function is mediated mainly by motor functions and marginally by cognitive capability. This structural model may allow future clinical therapists to design more effective task-related training protocols to promote the independence in daily function for stroke individuals.

Evolution and prediction of mismatch between observed and perceived upper limb function after stroke: a prospective, longitudinal, observational cohort study

BACKGROUND

A previously shown 'mismatch' group of patients with good observed upper limb (UL) motor function but low perceived UL activity at six months post stroke tends to use the affected UL less in daily life than would be expected based on clinical tests, and this mismatch may also be present at 12 months. We aimed to confirm this group in another cohort, to investigate the evolution of this group from six to 12 months, and to determine factors on admission to inpatient rehabilitation and at 6 months that can discriminate between mismatch and good match groups at 12 months.

METHODS

Persons after stroke were recruited on rehabilitation admission and re-assessed at six and 12 months. Observed UL function was measured with the upper extremity subscale of the Fugl-Meyer Assessment (FMA-UE) and perceived UL activity by the hand subscale of the Stroke Impact Scale 3.0 (SIS-Hand). We defined mismatch as good observed UL function (FMA-UE > 50/66) but low perceived activity (SIS-Hand≤75/100). Potential discriminators at admission and 6 months (demographic characteristics, stroke characteristics, UL somatosensory function, cognitive deficits, mental function and activity) were statistically compared for match and mismatch groups at 12 months.

RESULTS

We included 60 participants (female: 42%) with mean (SD) age of 65 (12) years. We confirmed a mismatch group of 11 (18%) patients at 6 months, which increased to 14 (23%) patients at 12 months. In the mismatch group compared to the good match group at 12 months, patients had a higher stroke severity and more somatosensory impairments on admission and at 6 months.

CONCLUSIONS

We confirmed a group of patients with good observed UL function but low perceived activity both at six and at 12 months post stroke. Assessment of stroke severity and somatosensory impairments on admission into rehabilitation could determine mismatch at 12 months and might warrant intervention. However, large differences in clinical outcomes between patients in the mismatch group indicate the importance of tailoring training to the individual needs.

Daily Life Upper Limb Activity for Patients with Match and Mismatch between Observed Function and Perceived Activity in the Chronic Phase Post Stroke

We investigated actual daily life upper limb (UL) activity in relation to observed UL motor function and perceived UL activity in chronic stroke in order to better understand and improve UL activity in daily life. In 60 patients, we collected (1) observed UL motor function (Fugl-Meyer Assessment (FMA-UE)), (2) perceived UL activity (hand subscale of the Stroke Impact Scale (SIS-Hand)), and (3) daily life UL activity (bilateral wrist-worn accelerometers for 72 h) data. Data were compared between two groups of interest, namely (1) good observed (FMA-UE >50) function and good perceived (SIS-Hand >75) activity (good match, n = 16) and (2) good observed function but low perceived (SIS-Hand ≤75) activity (mismatch, n = 15) with Mann-Whitney U analysis. The mismatch group only differed from the good match group in perceived UL activity (median (Q1-Q3) = 50 (30-70) versus 93 (85-100); p < 0.001). Despite similar observed UL motor function and other clinical characteristics, the affected UL in the mismatch group was less active in daily life compared to the good match group (p = 0.013), and the contribution of the affected UL compared to the unaffected UL for each second of activity (magnitude ratio) was lower (p = 0.022). We conclude that people with chronic stroke with low perceived UL activity indeed tend to use their affected UL less in daily life despite good observed UL motor function.

Prediction of Upper Limb use Three Months after Stroke: A Prospective Longitudinal Study

BACKGROUND

A major goal of upper limb (UL) rehabilitation after stroke is to facilitate the use of the paretic arm in daily life activities.

PURPOSE

To examine if UL impairment two weeks after stroke can predict real-life UL use at three months. Furthermore, to identify additional factors which contribute to future UL use, and characteristics of patients who do not achieve normal UL use.

METHODS

This study included patients with stroke ≥ 18 years. UL impairment was assessed by Fugl-Meyer upper extremity motor assessment (FM). Use ratio between affected and unaffected UL was assessed with accelerometers at three months after stroke. The association between FM score and UL use ratio was investigated with linear regression models and adjusted for secondary variables. Non-normal use was examined by a logistic regression.

RESULTS

Eighty-seven patients were included. FM score two weeks after stroke predicted 38% of the variance in UL use ratio three months after stroke. A multivariate regression model predicted 55%, and the significant predictors were FM, motor-evoked potential (MEP) status, and neglect. Non-normal use could be predicted with a high accuracy based on MEP and/or neglect. In a logistic regression sensitivity for prediction of non-normal use was 0.93 and specificity was 0.75.

CONCLUSION

Better baseline capacity of the paretic UL predicted increased use of the arm and hand in daily life. Non-normal UL use could be predicted reliably based on the absence of MEPs and/or presence of neglect.

Challenges and Opportunities for the Future of Brain-Computer Interface in Neurorehabilitation

Brain-computer interfaces (BCIs) provide a unique technological solution to circumvent the damaged motor system. For neurorehabilitation, the BCI can be used to translate neural signals associated with movement intentions into tangible feedback for the patient, when they are unable to generate functional movement themselves. Clinical interest in BCI is growing rapidly, as it would facilitate rehabilitation to commence earlier following brain damage and provides options for patients who are unable to partake in traditional physical therapy. However, substantial challenges with existing BCI implementations have prevented its widespread adoption. Recent advances in knowledge and technology provide opportunities to facilitate a change, provided that researchers and clinicians using BCI agree on standardisation of guidelines for protocols and shared efforts to uncover mechanisms. We propose that addressing the speed and effectiveness of learning BCI control are priorities for the field, which may be improved by multimodal or multi-stage approaches harnessing more sensitive neuroimaging technologies in the early learning stages, before transitioning to more practical, mobile implementations. Clarification of the neural mechanisms that give rise to improvement in motor function is an essential next step towards justifying clinical use of BCI. In particular, quantifying the unknown contribution of non-motor mechanisms to motor recovery calls for more stringent control conditions in experimental work. Here we provide a contemporary viewpoint on the factors impeding the scalability of BCI. Further, we provide a future outlook for optimal design of the technology to best exploit its unique potential, and best practices for research and reporting of findings.

Left hemisphere damage produces deficits in predictive control of bilateral coordination

Previous research has demonstrated hemisphere-specific motor deficits in ipsilesional and contralesional unimanual movements in patients with hemiparetic stroke due to MCA infarct. Due to the importance of bilateral motor actions on activities of daily living, we now examine how bilateral coordination may be differentially affected by right or left hemisphere stroke. To avoid the caveat of simply adding unimanual deficits in assessing bimanual coordination, we designed a unique task that requires spatiotemporal coordination features that do not exist in unimanual movements. Participants with unilateral left (LHD) or right hemisphere damage (RHD) and age-matched controls moved a virtual rectangle (bar) from a midline start position to a midline target. Movement along the long axis of the bar was redundant to the task, such that the bar remained in the center of and parallel to an imaginary line connecting each hand. Thus, to maintain midline position of the bar, movements of one hand closer to or further away from the bar midline required simultaneous, but oppositely directed displacements with the other hand. Our findings indicate that left (LHD), but not right (RHD) hemisphere-damaged patients showed poor interlimb coordination, reflected by significantly lower correlations between displacements of each hand along the bar axis. These left hemisphere-specific deficits were only apparent prior to peak velocity, likely reflecting predictive control of interlimb coordination. In contrast, the RHD group bilateral coordination was not significantly different than that of the control group. We conclude that predictive mechanisms that govern bilateral coordination are dependent on left hemisphere mechanisms. These findings indicate that assessment and training in cooperative bimanual tasks should be considered as part of an intervention framework for post-stroke physical rehabilitation.

The probability of choosing both hands depends on an interaction between motor capacity and limb-specific control in chronic stroke

A goal of rehabilitation after stroke is to promote pre-stroke levels of arm use for every day, frequently bimanual, functional activities. We reasoned that, after a stroke, the choice to use one or both hands for bimanual tasks might depend not only on residual motor capacity, but also the specialized demands imposed by the task on the paretic hand. To capture spontaneous, task-specific choices, we covertly observed 50 pre-stroke right-handed chronic stroke survivors (25 each of left, LHD, and right-hemisphere damage, RHD) and 11 age-similar control adults and recorded their hand use strategies for two pairs of bimanual tasks with distinct demands: one with greater precision requirements (photo-album tasks), and another with greater stabilization requirements (letter-envelope tasks). The primary outcome was the choice to use one or both hands. Logistic regression was used to test the two hypotheses that the probability of choosing a bimanual strategy would be greater in those with less severe motor impairment and also in those with LHD. When collapsed across the four tasks, we found support for these hypotheses. Notably, however, the influence of these factors on bimanual choice varied based on task demands. For the photo-album pair, the probability of a bimanual strategy was greater for those with LHD compared to RHD, regardless of the degree of motor impairment. For the letter-envelope pair, we found a significant interaction between impairment and side of lesion in determining the likelihood of choosing both hands. Therefore, the manner in which side of lesion moderates the effect of impairment on hand use depends on the task.