Touchscreen-based assessment of upper limb kinematics after stroke: Reliability, validity and sensitivity to motor impairment

BACKGROUND

Conventional clinical tools for assessing upper limb motor function often lack the sensitivity and specificity needed to detect subtle changes in motor performance and may be subject to bias. Kinematic assessment offers a potential solution by providing objective, precise, and detailed data on movement quality. However, it is typically associated with high costs, complex equipment, time-consuming procedures, and the need for controlled environments, all of which limit its accessibility and practicality in clinical settings. This study aimed to evaluate the reliability, validity, and sensitivity of a low-cost, touchscreen-based kinematic assessment tool for measuring upper limb function in individuals post-stroke.

METHODS

Sixty-four individuals with stroke participated in this study. Participants performed a visually guided reaching task on a large touch screen that consisted in reaching from a central target to five outer targets arranged in a circular pattern, each at a time, and then returning to the central target. Their motor function was assessed using the Fugl-Meyer Assessment for Upper Extremity, the Box and Block Test, and the Nine Hole Peg Test. Kinematic measures of the trajectories performed during the reaching task were extracted and analyzed for reliability, convergent validity with clinical assessments, and sensitivity to impairment severity.

RESULTS

The kinematic measures demonstrated good to excellent test-retest reliability, with intraclass correlation coefficients ranging from moderate to excellent. The convergent validity analysis revealed multiple significant correlations between the kinematic parameters and clinical assessments, particularly in tests requiring higher skill and precision, such as the Coordination and Speed subscale of the Fugl-Meyer Assessment for Upper Extremity and the Nine Hole Peg Test. Additionally, the touchscreen-based assessment was sensitive to the severity of motor impairment, as reflected by notable differences in the kinematic measures among participants with varying levels of upper limb function.

CONCLUSIONS

The touchscreen-based kinematic assessment offered an affordable yet reliable, valid, and sensitive alternative for evaluating upper limb kinematics in individuals with stroke, which could complement clinical assessments by offering additional insights into motor performance. Furthermore, its low cost, high speed, and ease of use make it a practical option for widespread clinical adoption.

Reliability, Concurrent Validity, Responsiveness and Measurement Error of the Portuguese Version of Comprehensive Motor Coordination Scale in Individuals With Parkinson's Disease

INTRODUCTION

Assessment of motor coordination in patients with Parkinson's disease (PD) is based on motor performance and does not consider movement quality.

OBJECTIVE

To validate the Comprehensive Coordination Scale (CCS) in patients with PD and correlate it with motor impairment.

METHODS

This cross-sectional and case-control study included 15 individuals with PD and 15 healthy older individuals as controls. Motor impairments were measured using the MDS-UPDRS (Part III). Motor coordination (CCS) was evaluated by five examiners and classified into four domains: upper and lower limbs and unilateral and bilateral tasks. CCS scores were compared between the groups using the Mann-Whitney test; concurrent validity was evaluated using Spearman's correlation between CCS and PD scales; and the inter-rate reliability was calculated by intraclass correlation coefficient (ICC).

RESULTS

There was significant difference between the groups in the upper limb (p < 0.001), lower limb (p = 0.006), unilateral (p < 0.001), bilateral (p = 0.015), and total (p < 0.001) CCS scores. Total CCS score (ICC 0.78), upper limb (ICC 0.71), lower limb (ICC 0.86) and unilateral (ICC 0.74) showed high inter-rate reliability. Bilateral domain (ICC 0.92) showed very high inter-rate reliability. And, there was negative correlation between CCS upper limb and postural tremor of hands (r = -0.716; p = 0.008), unilateral CCS domain with postural tremor of hands (r = -0.687; p = 0.012), and CCS total score with postural tremor of hands (r = -0.804; p = 0.002).

CONCLUSION

There was high inter-rater agreement for all CCS items, mainly in the lower limb and bilateral tasks. And, there was a moderate-to-very strong correlation between the total and sub-items of the CCS and motor impairment.

A pilot study for assessing NAO humanoid robot assistance in shoulder rehabilitation

Purpose

This study aimed to explore the potential application of NAO in guiding patients through rehabilitative exercises using external audiovisual stimuli, focusing on temporospatial control in terms of range of motion (ROM), execution time and movement smoothness.

Methods

This is a preliminary analysis involving ten healthy volunteers and two patients with shoulder musculoskeletal disorders. The protocol was developed in two phases (III and IV) with different ROM limits and including flexion-extension (FE), external-rotation (ER) and internal-rotation (IR) exercises, performed at two speeds and both with and without NAO assistance. Simultaneously, upper limb kinematics were assessed using a stereophotogrammetric system as a reference. Performance was evaluated by mean absolute error (MAE) for ROM and execution time, with smoothness assessed through Log Dimensionless Jerk analysis.

Results

In phase III, results for volunteers showed ROM differences in FE and ER, while IR was unaffected by NAO presence. In phase IV, NAO assistance resulted in reduced MAE across nearly all exercises. Patients who only performed phase III exercises at lower speed stayed within ROM limits for all movements performed with NAO, except for ER. For all the participants, results showed a significant reduction in the time MAE when using NAO. Patients exhibit greater smoothness during FE performed with NAO.

Conclusions

NAO showed potential in aiding patients with shoulder musculoskeletal disorders to replicate rehabilitation exercises, guiding both ROM and timing while influencing movement smoothness. NAO imitation could lead to improved rehabilitation outcomes and enhanced motor learning of motor skills, fostering greater adherence to prescribed therapy.

Level of Evidence

Level V, diagnostic.

Evaluating inter- and intra-rater reliability in assessing upper limb compensatory movements post-stroke: creating a ground truth through video analysis?

BACKGROUND

Compensatory movements frequently emerge in the process of motor recovery after a stroke. Given their potential for unfavorable long-term effects, it is crucial to assess and document compensatory movements throughout rehabilitation. However, clinically applicable assessment tools are currently limited. Deep learning methods have shown promising potential for assessing movement quality and addressing this gap. A crucial prerequisite for developing an accurate measurement tool is ensuring reliability in assessing compensatory movements, which is essential for establishing a valid ground truth.

OBJECTIVE

The study aimed to assess inter- and intra-rater reliability of occupational and physical therapists' visual assessment of compensatory movements based on video analysis.

METHODS

Experienced therapists evaluated video-recorded performances of a standardized drinking task through an online labeling system. The standardized drinking task was performed by seven individuals with mild to moderate upper limb motor impairments after a stroke. The therapists rated compensatory movements in predetermined body segments and movement phases using a slider with a continuous scale ranging from 0 (no compensation) to 100 (maximum compensation). The collected data were analyzed using a generalized-linear mixed effects model with zero-inflated beta regression to estimate variance components. Intraclass correlation coefficients (ICC) were calculated to assess inter- and intra-rater reliability.

RESULTS

Twenty-two therapists participated in this study. Inter-rater reliability was good for the phases of reaching, drinking, and returning (ICC ≥ .0.75), and moderate for both phases of transporting. Intra-rater reliability was excellent for the drinking phase (ICC > 0.9) and moderate to good for the phases of reaching, transporting, and returning of our cohort. ICCs for smoothness and interjoint coordination were poor for both inter- and intra-rater reliability. The data analysis unveiled a wide range of credible intervals for the ICCs across all domains examined in this study.

CONCLUSIONS

While this study shows promising inter- and intra-rater reliability for the drinking phases within our sample, the wide credible intervals raise the possibility that these results may have occurred by chance. Consequently, we cannot recommend the establishment of a ground truth for the automatic assessment of compensatory movements during a drinking task based on therapists' ratings alone.

Age-related differences in behavioral outcomes of bimanual functional motor tasks in children and adolescents with cerebral palsy: a scoping review

AIM

The objective of this review is to determine age-related differences in behavioral outcomes of bimanual motor tasks in children and adolescents with cerebral palsy (CP).

METHOD

This review followed the 6-stage Joanna Briggs Institute methodology. The Embase, EBSCO CINAHL, and PubMed databases were searched on May 2024. We included studies that employed instrumented measures to assess bimanual tasks in individuals with CP aged between 3 and 19 years.

RESULTS

Twenty-eight studies were included after full-text screening. This review reported on 544 individuals with CP. Bimanual tasks were grouped in seven categories and their varying complexities were listed and analyzed. There are numerous methods for assessing bimanual performance. The listed methods have shown that the gap between children with CP and healthy peers widens as task complexity increases. The data suggest that age-related outcomes result from a complex interaction between atypical development, the severity of deficits, and the context-dependent nature of the protocols.

CONCLUSION

The lack of standardized reporting on age-related results limits our understanding of bimanual developmental functions in CP. Standardizing these measures will enhance our understanding of bimanual function and better define the principles guiding therapeutic interventions, ultimately improving outcomes for individuals with CP.

Using a tablet to understand the spatial and temporal characteristics of complex upper limb movements in chronic stroke

Robotic devices are commonly used to quantify sensorimotor function of the upper limb after stroke; however, the availability and cost of such devices make it difficult to facilitate implementation in clinical environments. Tablets (e.g. iPad) can be used as devices to facilitate rehabilitation but are rarely used as assessment tools for the upper limb. The current study aimed to implement a tablet-based Maze Navigation Task to examine complex upper-limb movement in individuals with chronic stroke. We define complex upper-limb movement as reaching movements that require multi-joint coordination in a dynamic environment. We predicted that individuals with stroke would have more significant spatial errors, longer movement times, and slower speeds compared to controls with increasing task complexity. Twenty individuals with chronic stroke who had a variety of arm and hand function (Upper extremity Fugl-Myer 52.8 ± 18.3) and twenty controls navigated eight pseudorandomized mazes on an iPad using a digitizing stylus. The task was designed to elicit reaching movements engaging both the shoulder and elbow joints. Each maze became increasingly complex by increasing the number of 90° turns. We instructed participants to navigate each maze as quickly and accurately as possible while avoiding the maze's boundaries. Sensorimotor behavior was quantified using the following metrics: Error Time (time spent hitting or outside boundaries), Peak Speed, Average Speed, and Movement Time, Number of Speed Peaks. We found that individuals with stroke had significantly greater Error Time for all maze levels (all, p < 0.01), while both speed metrics, Movement Time and Number of Speed Peaks were significantly lower for several levels (all, p < 0.05). As maze complexity increased, the performance of individuals with stroke worsened only for Error Time while control performance remained consistent (p < 0.001). Our results indicate that a complex movement task on a tablet can capture temporal and spatial impairments in individuals with stroke, as well as how task complexity impacts movement quality. This work demonstrates that a tablet is a suitable tool for the assessment of complex movement after stroke and can serve to inform rehabilitation after stroke.

Psychometric properties of the modified reaching performance scale in persons with multiple sclerosis

BACKGROUND

A valid and reliable assessment tool to describe the quality of the movement pattern of reaching can provide valuable insights into motor performance deficits in persons with MS (pwMS). The Reaching Performance Scale, developed for stroke, is a promising scale to assess movement patterns in pwMS. However, psychometric properties of the scale are lacking in pwMS.

OBJECTIVES

Firstly, to investigate the content validity of the modified Reaching Performance Scale for application in patients with MS (mRPS). Secondly, to investigate the psychometric properties (within- and between-session reliability and concurrent validity) of the mRPS for pwMS.

METHODS

Forty-five pwMS (mean EDSS 6.6 pt, IQR 6-7.5) executed the mRPS that rates the quality of movement patterns and compensations during reach to grasp tasks. The content validity was determined by an expert panel based on observations of subjects performing the RPS. The reliability was based on five repetitions within one day, and between two days. For the concurrent validity, outcome measures at two levels of the International Classification of Functioning were correlated with the mRPS: Body Structure and Function level: Fugl-Meyer Assessment of the Upper Limb (FMA-UL), maximal isometric hand grip strength (HGS; Activity level: Action Research Arm Test (ARAT), Box and Blocks Test (BBT), Nine Hole Peg Test (NHPT) and Trunk Impairment Scale 2.0 (TIS 2.0) as well as perceived performance by the Manual Ability Measure-36 (MAM-36).

RESULTS

Scale modifications were made only on the ratings of the trunk displacement subscale. The mRPS had excellent agreement scores for within-session reliability (range of Kappa between 0.85 and 0.98) and moderate-to-excellent agreement scores for between-session reliability (K: 0.66-1.00). Regarding validity, the mRPS was highly correlated with the ARAT (rho=0.74, p < 0.001), followed by moderate correlations with trunk performance (TIS 2.0, rho= 0.61, p < 0.001), hand function (BBT: rho=0.64, p < 0.001; NHPT: rho=-0.61, p < 0.001) and perceived performance (MAM36 rho= 0.53, p < 0.001).

CONCLUSION

The mRPS is a reliable measurement tool to describe the movement pattern quality and motor compensations used during reaching in pwMS. Concerning concurrent validity, the mRPS is partially related to other measures of upper limb and trunk performance.

Multimodal Framework for Fine and Gross Upper-Limb Motor Coordination Assessment Using Serious Games and Robotics

A critical element of neurological function is eye–hand coordination: the ability of our vision system to coordinate the information received through the eyes to control, guide, and direct the hands to accomplish a task. Recent evidence shows that this ability can be disturbed by strokes or other neurological disorders, with critical consequences for motor behaviour. This paper presents a system based on serious games and multimodal devices aimed at improving the assessment of eye–hand coordination. The system implements gameplay that involves drawing specific patterns (labyrinths) to capture hand trajectories. The user can draw the path using multimodal devices such as a mouse, a stylus with a tablet, or robotic devices. Multimodal input devices can allow for the evaluation of complex coordinated movements of the upper limb that involve the synergistic motion of arm joints, depending on the device. A preliminary test of technological validation with healthy volunteers was conducted in the laboratory. The Dynamic Time Warping (DTW) index was used to compare hand trajectories without considering time-series lag. The results suggest that this multimodal framework allows for measuring differences between fine and gross motor skills. Moreover, the results support the viability of this system for developing a high-resolution metric for measuring eye–hand coordination in neurorehabilitation.

Investigation of the reliability and validity of the Turkish version of the Comprehensive Coordination Scale in patients with Parkinson's disease

OBJECTIVE

The Comprehensive Coordination Scale (CCS) is a valid, reliable scale for evaluating motor coordination, described as the ability to produce context-dependent movements of multiple body parts in both spatial and temporal domains in patients with chronic stroke. The aim of this study was to develop a Turkish version of the CCS that can be used to evaluate coordination in Parkinson's disease patients and to test its validity and reliability.

METHODS

Thirty-four patients with Parkinson's disease (18 females, 16 males) with a mean age of 67.55± 10.93 years were included. The 9-Hole Peg Test (9 HPT), Timed Up and Go Test (TUG), Berg Balance Scale (BBS), Functional Reach Test (FRT), and Modified Hoehn and Yahr (H&Y) were administered to the patients.

RESULTS

In the correlation analysis for convergent validity, the CCS-TR showed a moderate negative correlation with both the 9 HPT and the TUG test (r=-0.684 and -0.641, respectively). There were also moderate positive correlations observed between the CCS-TR and the FRT and BBS (r=0.607 and 0.657, respectively). The total CCS-TR had excellent intrarater reliability (ICC=0.99; 95 % CI: 0.98-0.99) and interrater reliability (ICC=0.90; 95 % CI: 0.81-0.95). The CCS-TR subscales had excellent intrarater reliability (ICC: range 0.98 from 0.99). For intrarater agreement, the ICC was 0.99, and for interrater agreement, the ICC was 0.90 (excellent agreement).

CONCLUSION

The results of the present study indicate that the Turkish version of the CCS is a reliable and valid coordination scale that can be used in patients with Parkinson's disease.

Comparison of inter-joint coordination strategies during activities of daily living with prosthetic and anatomical limbs

While healthy individuals have redundant degrees of freedom of the joints, they coordinate their multi-joint movements such that the redundancy is effectively reduced. Achieving high inter-joint coordination may be difficult for upper limb prosthesis users due to the lack of proprioceptive feedback and limited motion of the terminal device. This study compared inter-joint coordination between prosthesis users and individuals without limb loss during different upper limb activities of daily living (ADLs). Nine unilateral prosthesis users (five males) and nine age- and sex-matched controls without limb loss completed three unilateral and three bilateral ADLs. Principal component analysis was applied to the three-dimensional motion trajectories of the trunk and arms to identify coordinative patterns. For each ADL, we quantified the cumulative variance accounted for (VAF) of the first five principal components (pcs), which was the lowest number of pcs that could achieve 90% VAF in control limb movements across all ADLs (5 ≤ n ≤ 9). The VAF was lower for movements involving a prosthesis compared to those completed by controls across all ADLs (p < 0.001). The pc waveforms were similar between movements involving a prosthesis and movements completed by control participants for pc1 (r > 0.78, p < 0.001). The magnitude of the relationship for pc2 and pc3 differed between ADLs, with the strongest correlation for symmetric bilateral ADLs (0.67 ≤ r ≤ 0.97, p < 0.001). Collectively, this study demonstrates that activities of daily living were completed with distinct coordination strategies in prosthesis users compared to individuals without limb loss. Future work should explore how device features, such as the availability of sensory feedback or motorized wrist joints influence multi-joint coordination.

Recommendations for Upper Limb Motor Recovery: An Overview of the UK and European Rehabilitation after Stroke Guidelines (2023)

Upper limb impairment is common after stroke, with a significant impact on the stroke survivor's function, social participation and quality of life. Clinical guidelines are needed to inform clinical practise, tailor interventions to improve outcomes and address unresolved research questions. This review contributes to the evidence guiding clinical practise for upper limb motor recovery after stroke by summarising the recommendations from the UK rehabilitation guidelines (National Institute for Health and Care Excellence (NICE) and the Intercollegiate Stroke Working Party (ISWP)) and the European Stroke Organisation (ESO) guidelines, all published in 2023. All three guidelines target researchers, clinical practitioners, stroke survivors and their social networks. An important feature in all three guidelines was therapeutic intensity, with all guidelines recommending increased therapeutic intensity. Unlike the ESO, the NICE and ISWP additionally include specific research recommendations. While the NICE guidelines seem more holistic and target a wider audience, the three guidelines are complimentary. We recommend that a future consensus statement should be developed in partnership between all three organisations, agreeing on scope and using the same terminology, on recommendations to improve stroke rehabilitation in the UK and Europe.

Quantitative Assessment via Multi-Domain Fusion of Muscle Synergy Associated With Upper-Limb Motor Function for Stroke Rehabilitation

Quantitative assessment of upper limb motor function aids therapists in providing appropriate rehabilitation strategies, which plays an essential role in post-stroke rehabilitation. Traditional assessments, relying on clinical scales or kinematic metrics, often involve subjective scores or are influenced by compensatory strategies. Recently, the use of muscle synergies, representing simplified neuromuscular control, has emerged as a promising approach for post-stroke assessment. In general, muscle synergies are decomposed into two components: synergy vectors and synergy activation. Synergy vectors represent the relative weighting of each muscle within each synergy, that is muscle coordination; synergy activation represents the recruitment of the muscle synergy over time, that is muscle activation strength. Both components are vital for adequately assessing patients' motor function. Therefore, we integrate the spatial domain and temporal domain features extracted from synergy vectors and synergy activation, constructing a multi-domain assessment system using a Random Forest classifier, which may provide great qualitative classification accuracy. Furthermore, a novel functional score is generated from the probabilities belonging to the pathological group. Finally, A study involving ten healthy subjects and ten post-stroke patients validates the proposed method. The experimental results show that the classification accuracy was enhanced to 98.56% by fusing the characteristics derived from different domains, which was higher than that based on spatial domain (94.90%) and temporal domain (91.08%), respectively. Furthermore, the assessment score generated by multi-domain fusion framework exhibited a significant correlation with the clinical score. These promising results show the potential of applying the proposed method to clinical assessments for post-stroke patients.

Spatiotemporal variability after stroke reflects more than just slow walking velocity

BACKGROUND

Increased spatiotemporal gait variability is considered a clinical biomarker of ageing and pathology, and a predictor of future falls. Nevertheless, it is unclear whether the increased spatiotemporal variability observed in persons with stroke is directly related to the pathology or simply reflects their choice of walking velocity.

RESEARCH QUESTION

Does increased spatiotemporal gait variability directly relate to motor coordination deficits after stroke?

METHODS

Forty persons with stroke participated in this cross-sectional study. Participants performed the lower-extremity motor coordination test (LEMOCOT) on an electronic mat equipped with force sensors. Then, participants walked for 120 s on a computerized treadmill at their comfortable walking velocity. For the LEMOCOT we used the traditional score of in-target touch count and computed the absolute and variable error around the targets. For gait variability, we extracted the standard deviation of step time, step length, step velocity, and step width. Using linear modeling, we tested the correlations of gait variability with the outcome measures from the LEMOCOT, after controlling for walking velocity.

RESULTS

The variability in step time, step length and step width correlated with walking velocity, while the variability in step velocity did not. After controlling for walking velocity, we observed that the LEMOCOT score correlated with the variance in step time, and the variable error in the LEMOCOT correlated with the variance in step length, in step width, and in step velocity. No significant correlation with any of the velocity-controlled step parameters was found for the absolute error in the LEMOCOT.

SIGNIFICANCE

Decreased performance in the LEMOCOT was associated with increased spatiotemporal variability in persons with stroke, regardless of their walking velocity. Our results demonstrate the connection between lower-extremity coordination impairments and deficits in gait function.

Upper limb motor dysfunction is associated with fragmented kinetics after brain injury

BACKGROUND

Characterization of motor deficits after brain injury is important for rehabilitation personalization. While studies reported abnormalities in the kinematics of paretic and non-paretic elbow extension for patients with brain injuries, kinematic analysis is not sufficient to explore how patients deal with musculoskeletal redundancy and the energetic aspect of movement execution. Conversely, interarticular coordination and movement kinetics can reflect patients' motor strategies. This study investigates motor strategies of paretic and non-paretic upper limb after brain injury to highlight motor deficits or compensation strategies.

METHODS

26 brain-injured hemiplegic patients and 24 healthy controls performed active elbow extensions in the horizontal plane, with both upper limbs for patients and, with the dominant upper limb for controls. Elbow and shoulder kinematics, interarticular coordination, net joint kinetics were quantified.

FINDINGS

Results show alterations in kinematics, and a strong correlation between elbow and shoulder angles, as well as time to reach elbow and shoulder peak angular velocity in both upper limbs of patients. Net joint kinetics were lower for paretic limb and highlighted a fragmented motor strategy with increased number of transitions between concentric and eccentric phases.

INTERPRETATION

In complement to kinematic results, our kinetic results confirmed patients' difficulties to manage both spatially and temporally the joint degrees of freedom redundancy but revealed a fragmented compensatory motor strategy allowing patients upper limb extension despite quality alteration and decrease in energy efficiency. Motor rehabilitation should improve the management of this fragmentation strategy to improve the performance and the efficiency of active movement after brain injury.

Intra-limb joint coordination measures of upper limb and hand movements: A systematic review

BACKGROUND

People with central nervous system disorders typically have difficulties in coordination of the upper limb and hand movements, which significantly impairs their activities of daily living. Laboratory-based measures can provide quantitative and objective information about intra-limb coordination to aid the rehabilitation process of this population. However, there is currently no comprehensive review of laboratory-based measures.

RESEARCH QUESTIONS

The aim of this review was to identify and summarize laboratory-based intra-limb coordination measures for different upper limb and hand movements.

METHODS

Searches were performed in the CINAHL, Embase, IEEE Xplore, MEDLINE, PubMed and Web of Science databases to identify studies published between 2013 and 2022. Two authors independently performed paper selection, data extraction and quality assessment.

RESULTS

21 papers were identified, and six types of coordination measures were classified. These included principal component analysis, continuous relative phase analysis, correlation analysis, regression analysis, uncontrolled manifold analysis, and uncorrelated surrogate data analysis, in descending order of occurrence. Regarding psychometric properties, all measures demonstrated good discriminative validity. However, only the principal component analysis approach and the continuous relative phase analysis approach were found to have good convergent validity and responsiveness, respectively. In terms of their practicality, these measures were primarily utilized for quantifying coordination in individuals with neurological disorders, with a greater emphasis on the coordination of upper limb movements rather than hand movements.

SIGNIFICANCE

This review summarized and critiqued the characteristics of six types of joint coordination measures. Researchers and clinicians should therefore select appropriate measures based on individual needs. Future research should continue on analysing coordination in individuals with pathological conditions and exploring the application of these measures in quantifying hand movement coordination, to advance current knowledge and inform rehabilitation practices.

Integrating Motor Variability Evaluation Into Movement System Assessment

Common assessment tools for determining therapeutic success in rehabilitation typically focus on task-based outcomes. Task-based outcomes provide some understanding of the individual's functional ability and motor recovery; however, these clinical outcomes may have limited translation to a patient's functional ability in the real world. Limitations arise because (1) the focus on task-based outcome assessment often disregards the complexity of motor behavior, including motor variability, and (2) mobility in highly variable real-world environments requires movement adaptability that is made possible by motor variability. This Perspective argues that incorporating motor variability measures that reflect movement adaptability into routine clinical assessment would enable therapists to better evaluate progress toward optimal and safe real-world mobility. The challenges and opportunities associated with incorporating variability-based assessment of pathological movements are also discussed. This Perspective also indicates that the field of rehabilitation needs to leverage technology to advance the understanding of motor variability and its impact on an individual's ability to optimize movement.

IMPACT

This Perspective contends that traditional therapeutic assessments do not adequately evaluate the ability of individuals to adapt their movements to the challenges faced when negotiating the dynamic environments encountered during daily life. Assessment of motor variability derived during movement execution can address this issue and provide better insight into a patient's movement stability and maneuverability in the real world. Creating such a shift in motor system assessment would advance understanding of rehabilitative approaches to motor system recovery and intervention.

A guide to inter-joint coordination characterization for discrete movements: a comparative study

Characterizing human movement is essential for understanding movement disorders, evaluating progress in rehabilitation, or even analyzing how a person adapts to the use of assistive devices. Thanks to the improvement of motion capture technology, recording human movement has become increasingly accessible and easier to conduct. Over the last few years, multiple methods have been proposed for characterizing inter-joint coordination. Despite this, there is no real consensus regarding how these different inter-joint coordination metrics should be applied when analyzing the coordination of discrete movement from kinematic data. In this work, we consider 12 coordination metrics identified from the literature and apply them to a simulated dataset based on reaching movements using two degrees of freedom. Each metric is evaluated according to eight criteria based on current understanding of human motor control physiology, i.e, each metric is graded on how well it fulfills each of these criteria. This comparative analysis highlights that no single inter-joint coordination metric can be considered as ideal. Depending on the movement characteristics that one seeks to understand, one or several metrics among those reviewed here may be pertinent in data analysis. We propose four main factors when choosing a metric (or a group of metrics): the importance of temporal vs. spatial coordination, the need for result explainability, the size of the dataset, and the computational resources. As a result, this study shows that extracting the relevant characteristics of inter-joint coordination is a scientific challenge and requires a methodical choice. As this preliminary study is conducted on a limited dataset, a more comprehensive analysis, introducing more variability, could be complementary to these results.

Shoulder complex and trunk coordination of individuals with severe hemiparesis following a constraint-induced movement therapy protocol: A case series

INTRODUCTION

Constraint Induced Movement Therapy (CIMT) has been shown to be an effective rehabilitation technique in individuals with mild and moderate upper limb (UL) hemiparesis. The aim was to evaluate the effect the CIMT for improving paretic UL use and interjoint coordination with individuals in severe hemiparesis.

METHODS

Six individuals with severe chronic hemiparesis (mean age = 55 ± 16 years) received a UL CIMT intervention for 2 weeks. UL clinical assessments were conducted five times: two assessments at pre-intervention and then, one assessment at post-intervention and 1- and 3-month follow-up using the Graded Motor Activity Log GMAL) and the Graded Wolf Motor Function Test (GWMFT). Scapula, humerus and trunk coordination variability were assessed using the 3-D kinematics during arm elevation, combing hair, turning on the switch and grasp a washcloth. A paired t-test was used to check differences between coordination variability and a one-way ANOVA repeated measures was used to check differences between GMAL and GWMFT scores.

RESULTS

There were no differences in GMAL and GWMFT between the patient screening and the baseline data collection (p > 0.05). GMAL scores increased at post-intervention and at follow-ups (p < 0.02). GWMFT performance time score decreased at post-intervention and at 1-month follow-up (p < 0.04). Improvements in kinematic variability of the paretic UL at pre and post-intervention were observed in all tasks, except in the activity of turn on the light switch.

CONCLUSION

Following the CIMT protocol, improvements in GMAL and GWMFT scores may reflect improvements in paretic UL performance, in real-life environment. Improvements in kinematic variability may reflect an improving of UL interjoint coordination for individuals with chronic severe hemiparesis.

Muscle synergies for evaluating upper limb in clinical applications: A systematic review

INTRODUCTION

Muscle synergies have been proposed as a strategy employed by the central nervous system to control movements. Muscle synergy analysis is a well-established framework to examine the pathophysiological basis of neurological diseases and has been applied for analysis and assessment in clinical applications in the last decades, even if it has not yet been widely used in clinical diagnosis, rehabilitative treatment and interventions. Even if inconsistencies in the outputs among studies and lack of a normative pipeline including signal processing and synergy analysis limit the progress, common findings and results are identifiable as a basis for future research. Therefore, a literature review that summarizes methods and main findings of previous works on upper limb muscle synergies in clinical environment is needed to i) summarize the main findings so far, ii) highlight the barriers limiting their use in clinical applications, and iii) suggest future research directions needed for facilitating translation of experimental research to clinical scenarios.

METHODS

Articles in which muscle synergies were used to analyze and assess upper limb function in neurological impairments were reviewed. The literature research was conducted in Scopus, PubMed, and Web of Science. Experimental protocols (e.g., the aim of the study, number and type of participants, number and type of muscles, and tasks), methods (e.g., muscle synergy models and synergy extraction methods, signal processing methods), and the main findings of eligible studies were reported and discussed.

RESULTS

383 articles were screened and 51 were selected, which involved a total of 13 diseases and 748 patients and 1155 participants. Each study investigated on average 15 ± 10 patients. Four to forty-one muscles were included in the muscle synergy analysis. Point-to-point reaching was the most used task. The preprocessing of EMG signals and algorithms for synergy extraction varied among studies, and non-negative matrix factorization was the most used method. Five EMG normalization methods and five methods for identifying the optimal number of synergies were used in the selected papers. Most of the studies report that analyses on synergy number, structure, and activations provide novel insights on the physiopathology of motor control that cannot be gained with standard clinical assessments, and suggest that muscle synergies may be useful to personalize therapies and to develop new therapeutic strategies. However, in the selected studies synergies were used only for assessment; different testing procedures were used and, in general, study-specific modifications of muscle synergies were observed; single session or longitudinal studies mainly aimed at assessing stroke (71% of the studies), even though other pathologies were also investigated. Synergy modifications were either study-specific or were not observed, with few analyses available for temporal coefficients. Thus, several barriers prevent wider adoption of muscle synergy analysis including a lack of standardized experimental protocols, signal processing procedures, and synergy extraction methods. A compromise in the design of the studies must be found to combine the systematicity of motor control studies and the feasibility of clinical studies. There are however several potential developments that might promote the use of muscle synergy analysis in clinical practice, including refined assessments based on synergistic approaches not allowed by other methods and the availability of novel models. Finally, neural substrates of muscle synergies are discussed, and possible future research directions are proposed.

CONCLUSIONS

This review provides new perspectives about the challenges and open issues that need to be addressed in future work to achieve a better understanding of motor impairments and rehabilitative therapy using muscle synergies. These include the application of the methods on wider scales, standardization of procedures, inclusion of synergies in the clinical decisional process, assessment of temporal coefficients and temporal-based models, extensive work on the algorithms and understanding of the physio-pathological mechanisms of pathology, as well as the application and adaptation of synergy-based approaches to various rehabilitative scenarios for increasing the available evidence.

The multi-grip and standard myoelectric hand prosthesis compared: does the multi-grip hand live up to its promise?

BACKGROUND

Multi-grip myoelectric hand prostheses (MHPs), with five movable and jointed fingers, have been developed to increase functionality. However, literature comparing MHPs with standard myoelectric hand prostheses (SHPs) is limited and inconclusive. To establish whether MHPs increase functionality, we compared MHPs with SHPs on all categories of the International Classification of Functioning, Disability, and Health-model (ICF-model).

METHODS

MHP users (N = 14, 64.3% male, mean age = 48.6 years) performed physical measurements (i.e., Refined Clothespin Relocation Test (RCRT), Tray-test, Box and Blocks Test, Southampton Hand Assessment Procedure) with their MHP and an SHP to compare the joint angle coordination and functionality related to the ICF-categories 'Body Function' and 'Activities' (within-group comparisons). SHP users (N = 19, 68.4% male, mean age = 58.1 years) and MHP users completed questionnaires/scales (i.e., Orthotics and Prosthetics Users' Survey-The Upper Extremity Functional Status Survey /OPUS-UEFS, Trinity Amputation and Prosthesis Experience Scales for upper extremity/TAPES-Upper, Research and Development-36/RAND-36, EQ-5D-5L, visual analogue scale/VAS, the Dutch version of the Quebec User Evaluation of Satisfaction with assistive technology/D-Quest, patient-reported outcome measure to assess the preferred usage features of upper limb prostheses/PUF-ULP) to compare user experiences and quality of life in the ICF-categories 'Activities', 'Participation', and 'Environmental Factors' (between-group comparisons).

RESULTS

'Body Function' and 'Activities': nearly all users of MHPs had similar joint angle coordination patterns with an MHP as when they used an SHP. The RCRT in the upward direction was performed slower in the MHP condition compared to the SHP condition. No other differences in functionality were found. 'Participation': MHP users had a lower EQ-5D-5L utility score; experienced more pain or limitations due to pain (i.e., measured with the RAND-36). 'Environmental Factors': MHPs scored better than SHPs on the VAS-item holding/shaking hands. The SHP scored better than the MHP on five VAS-items (i.e., noise, grip force, vulnerability, putting clothes on, physical effort to control) and the PUF-ULP.

CONCLUSION

MHPs did not show relevant differences in outcomes compared to SHPs on any of the ICF-categories. This underlines the importance of carefully considering whether the MHP is the most suitable option for an individual taking into account the additional costs of MHPs.

A Pilot Study of Compensatory Strategies for Reach-to-Grasp-Pen in Patients with Stroke

Coordinated reaching and grasping movements may be impaired in patients with poststroke hemiplegia. Patients frequently adopt compensatory strategies, which require investigation. This pilot study used kinematic parameters to examine compensatory strategies by assessing the reach-to-grasp-pen movements in patients with stroke and unaffected participants. Twelve patients with stroke with mild impairment (45.16 ± 12.62 years, 2.41 ± 1.97 months), twelve with moderate impairment (50.41 ± 12.92 years, 3.83 ± 3.58 months), and ten healthy individuals (20.6 ± 0.69 years) performed a reach-to-grasp-pen task. Kinematics parameters of upper limb and fingers, such as movement time, number of movement units, index of curvature, spectral arc length, trunk forward transition, trunk lateral transition, elbow extension, shoulder flexion, shoulder abduction, trunk rotation, arm-plane angle, the joint angles of interphalangeal joints of the thumb, index, middle, ring, and little fingers were examined in the study. These parameters were evaluated with two Microsoft Azure Kinect and Leap Motion, which belong to markerless motion capture systems. Patients with stroke showed longer reaching movement time, less smooth movement trajectories, and more trunk rotation (P < 0.05). In patients with stroke, the metacarpophalangeal joint (MCP) and proximal interphalangeal joint (PIP) of the thumb were flexed in the starting position; the MCP and PIP joints of the index finger in the stroke group were more extended during pen grasp; the range of motion of the MCP of the middle finger and the PIP joints of the middle, ring, and little fingers became greater, suggesting a larger peak aperture (P < 0.05). The more significant extension was observed in the index finger at the end of the grasp, suggesting inadequate flexion (P < 0.05). In clinical practice, the reach-to-grasp-pen task using markless sensing technology can effectively distinguish patients with stroke from healthy individuals and evaluate the recovery and compensation strategies of upper limb and hand functions. It can potentially become an evaluation tool in hospital and community scenes. Accurate identification of abnormal trunk, arm, and finger strategies is crucial for therapists to develop targeted upper limb treatment methods and evaluate treatment effects.

Clinical Motor Coordination Tests in Adult Neurology: A Scoping Review

Purpose: This scoping review aimed to identify which clinical tests are used to assess upper limb, lower limb, and trunk motor coordination, and their metric and measurement properties for adult neurological populations. Method: MEDLINE (1946-) and EMBASE (1996-) databases were searched using keywords such as movement quality, motor performance, motor coordination, assessment, and psychometrics. Data regarding the body part assessed, neurological condition, psychometric properties, and scored metrics of spatial and/or temporal coordination were independently extracted by two reviewers. Alternate versions of some tests such as the Finger-to-Nose Test were included. Results: Fifty-one included articles yielded 2 tests measuring spatial coordination, 7 tests measuring temporal coordination, and 10 tests measuring both. Scoring metrics and measurement properties differed between tests, with a majority of tests having good-to-excellent measurement properties. Conclusions: The metrics of motor coordination scored by current tests vary. Since tests do not assess functional task performance, the onus falls on clinicians to infer the connection between coordination impairments and functional deficits. Clinical practice would benefit from the development of a battery of tests that assesses the metrics of coordination related to functional performance.

Quantitative Assessment of Hand Motor Function for Post-Stroke Rehabilitation Based on HAGCN and Multimodality Fusion

Quantitative assessment of hand function can assist therapists in providing appropriate rehabilitation strategies, which plays an essential role in post-stroke rehabilitation. Conventionally, the assessment process relies heavily on clinical experience and lacks quantitative analysis. To quantitatively assess the hand motor function of patients with post-stroke hemiplegia, this study proposes a novel multi-modality fusion assessment framework. This framework includes three components: the kinematic feature extraction based on a graph convolutional network (HAGCN), the surface electromyography (sEMG) signal processing based on a multi-layer long short term memory (LSTM) network, and the quantitative assessment based on the multi-modality fusion. To the best of the authors' knowledge, this is the first study of applying a graph convolution network to assess the hand motor function. We also collect the kinematic data and sEMG data from 70 subjects who completed 28 types of hand movements. Therapists first graded patients using traditional motor assessment scales (Brunnstrom Scale and Fugl-Meyer Assessment Scale) and further refined the patient's motor assessment result by their experience. Then, we trained the HAGCN and LSTM networks and quantitatively assessed each patient based on the proposed assessment framework. Finally, the Spearman correlation coefficient (SC) between the assessment result of this study and the traditional scale are 0.908 and 0.967, demonstrating a significant correlation between the proposed assessment and the traditional scale scores. In addition, the SC value between the score of this study and the refined hand motor function is 0.997, indicating the "ceiling effect" of some traditional scales can be avoided.

Smoothness of movement in idiopathic cervical dystonia

Smoothness (i.e. non-intermittency) of movement is a clinically important property of the voluntary movement with accuracy and proper speed. Resting head position and head voluntary movements are impaired in cervical dystonia. The current work aims to evaluate if the smoothness of voluntary head rotations is reduced in this disease. Twenty-six cervical dystonia patients and 26 controls completed rightward and leftward head rotations. Patients’ movements were differentiated into “towards-dystonia” (rotation accentuated the torticollis) and “away-dystonia”. Smoothness was quantified by the angular jerk and arc length of the spectrum of angular speed (i.e. SPARC, arbitrary units). Movement amplitude (mean, 95% CI) on the horizontal plane was larger in controls (63.8°, 58.3°–69.2°) than patients when moving towards-dystonia (52.8°, 46.3°–59.4°; P = 0.006). Controls’ movements (49.4°/s, 41.9–56.9°/s) were faster than movements towards-dystonia (31.6°/s, 25.2–37.9°/s; P < 0.001) and away-dystonia (29.2°/s, 22.9–35.5°/s; P < 0.001). After taking into account the different amplitude and speed, SPARC-derived (but not jerk-derived) indices showed reduced smoothness in patients rotating away-dystonia (1.48, 1.35–1.61) compared to controls (1.88, 1.72–2.03; P < 0.001). Poor smoothness is a motor disturbance independent of movement amplitude and speed in cervical dystonia. Therefore, it should be assessed when evaluating this disease, its progression, and treatments.

Association between self-perceived activity performance and upper limb functioning in subacute stroke

BACKGROUND AND PURPOSE

This study aimed to investigate to what extent upper limb (UL) motor impairment, trunk compensation, and activity performance are related to self-perception of UL activity performance in subacute stroke.

METHODS

This was a prospective observational study. Twenty-four adults with subacute stroke (age: 65.4 ± 10.8 years) underwent clinical and kinematic assessments at baseline (33.9 ± 5.2 days after stroke onset) and 4 weeks after the baseline. The clinical assessment included the UL Fugl-Meyer motor assessment (FMA), Simple Test for Evaluating hand Function (STEF), and the performance and satisfaction scores of the Canadian Occupational Performance Measure (COPM). The kinematic measurement was performed using a motion capture system during a standardized reach-to-grasp task. Endpoint performance variables and trunk displacement were calculated as kinematic outcomes. An inpatient rehabilitation program of 3 h/day was provided every day for 4 weeks between the two measurement points. The relationships between COPM scores and clinical/kinematic outcomes were examined by multiple regression analysis. Significance levels of p < 0.05 were used.

RESULTS

The results of the multiple regression analysis showed that the changes in STEF (β = 0.520, p = 0.005) and trunk compensation (β = -0.398, p = 0.024) were moderately related to the change in the COPM satisfaction (R² _adj  = 0.426, p = 0.001), while the change in UL FMA was not.

DISCUSSION

The changes in activity performance and trunk compensation were related to improved self-perception of UL activity performance. Therapeutic management for activity performance and trunk compensation may be important for improving self-perception of UL activity performance after stroke.

Bilateral motor coordination during upper limb symmetric pushing movements at two levels of force resistance in healthy and post-stroke individuals

BACKGROUND

Impairments of the upper limb (UL) are common after a stroke and may affect bilateral coordination. A better understanding of UL bilateral coordination is required for designing innovative rehabilitation strategies.

OBJECTIVE

To assess bilateral coordination after stroke using time-distance, velocity and force parameters during an UL bilateral task performed by simultaneously pushing handles on a bilateral exerciser at two levels of force.

METHODS

Two groups were included to assess bilateral coordination on a newly designed bimanual exerciser- One group of individuals at least 3 months post-stroke (n = 19) with moderate impairment and one group of healthy individuals (n = 20). Participants performed linear movements by pushing simultaneously with both hands on instrumented handles. The task consisted of two one-minute trials performed in sitting at two levels of participants' maximum force (MF): 30% and 15%, with visual feedback. Time-distance parameters, spatial, velocity and force profiles were compared between groups, between levels of resistance and the first part (0-50%) and entire duration of the pushing cycles (0-100%).

RESULTS

The mean pushing time was longer at 30% MF compared to 15% MF in the stroke group. Spatial profiles, represented by hand positions on the rail, revealed that the paretic hand lagged slightly behind throughout the cycle. For velocity, both groups displayed good coordination. It was less coupled at 30% than 15% MF and a trend was observed toward more lag occurrence in the stroke group. Except for lower forces on the paretic side in the stroke group, the shape of the force profiles was similar between groups, sides and levels of resistance. For all parameters, the coordination was good up to 75% of the pushing cycle and decreased toward the end of the cycle.

CONCLUSIONS

Individuals after stroke presented with overall spatial and temporal coupling of the UL during bilateral pushing movements. The relay of information at different levels of the nervous system might explain the coordinated pushing movements and might be interesting for training UL coordination.

Motor learning in neurological rehabilitation

While most upper limb training interventions in neurological rehabilitation are based on established principles of motor learning and neural plasticity, recovery potential may be improved if the focus includes remediating an individual's specific motor impairment within the framework of a motor control theory. This paper reviews current theories of motor control and motor learning and describes how they can be incorporated into training programs to enhance sensorimotor recovery in patients with neurological lesions. An emphasis is placed on dynamical systems theory and the use of new technologies such as virtual, augmented and mixed reality applications for rehabilitation to facilitate learning.Implications for RehabilitationKinematic abundance allows the healthy nervous system to produce different combinations of joint rotations to perform a desired task.The structure of practice to improve the movement repertoire in rehabilitation should take into account the kinematic abundance of the system.Learning can be enhanced by varied practice with feedback about key movement elements.Virtual reality environments provide opportunities to manipulate the structure and schedule of practice and feedback.

Path Planning and Impedance Control of a Soft Modular Exoskeleton for Coordinated Upper Limb Rehabilitation

The coordinated rehabilitation of the upper limb is important for the recovery of the daily living abilities of stroke patients. However, the guidance of the joint coordination model is generally lacking in the current robot-assisted rehabilitation. Modular robots with soft joints can assist patients to perform coordinated training with safety and compliance. In this study, a novel coordinated path planning and impedance control method is proposed for the modular exoskeleton elbow-wrist rehabilitation robot driven by pneumatic artificial muscles (PAMs). A convolutional neural network-long short-term memory (CNN-LSTM) model is established to describe the coordination relationship of the upper limb joints, so as to generate adaptive trajectories conformed to the coordination laws. Guided by the planned trajectory, an impedance adjustment strategy is proposed to realize active training within a virtual coordinated tunnel to achieve the robot-assisted upper limb coordinated training. The experimental results showed that the CNN-LSTM hybrid neural network can effectively quantify the coordinated relationship between the upper limb joints, and the impedance control method ensures that the robotic assistance path is always in the virtual coordination tunnel, which can improve the movement coordination of the patient and enhance the rehabilitation effectiveness.

Construct Validity of the Upper-Limb Interlimb Coordination Test in Stroke

Background

Coordination impairments are under-evaluated in patients with stroke due to the lack of validated assessments resulting in an unclear relationship between coordination deficits and functional limitations.

Objective

Determine the construct validity of the new clinical upper-limb (UL) Interlimb Coordination test (ILC2) in individuals with chronic stroke.

Methods

Thirteen individuals with stroke, ≥40 years, with ≥30° isolated supination of the more-affected (MAff) arm, who could understand instructions and 13 healthy controls of similar age participated in a cross-sectional study. Participants performed synchronous bilateral anti-phase forearm rotations for 10 seconds in 4 conditions: self-paced internally-paced (IP1), fast internally-paced (IP2), slow externally-paced (EP1), and fast externally-paced (EP2). Primary (continuous relative phase-CRP, cross-correlation, lag) and secondary outcome measures (UL and trunk kinematics) were compared between groups.

Results

Participants with stroke made slower UL movements than controls in all conditions, except EP1. Cross-correlation coefficients were lower (i.e., closer to 0) in stroke in IP1, but CRP and lag were similar between groups. In IP1 and matched-speed conditions (IP1 for healthy and IP2 for stroke), stroke participants used compensatory trunk and shoulder movements. The synchronicity sub-scale and total scores of ILC2 were related to temporal coordination in IP2. Interlimb Coordination test total score was related to greater shoulder rotation of the MAff arm. Interlimb Coordination test scores were not related to clinical scores.

Conclusion

Interlimb Coordination test is a valid clinical measure that may be used to objectively assess UL interlimb coordination in individuals with chronic stroke. Further reliability testing is needed to determine the clinical utility of the scale.

Insights into motor performance deficits after stroke: an automated and refined analysis of the lower-extremity motor coordination test (LEMOCOT)

Background

The lower-extremity motor coordination test (LEMOCOT) is a performance-based measure used to assess motor coordination deficits after stroke. We aimed to automatically quantify performance on the LEMOCOT and to extract additional performance parameters based on error analysis in persons with stroke (PwS) and healthy controls. We also aimed to explore whether these parameters provide additional information regarding motor control deficit that is not captured by the traditional LEMOCOT score. In addition, the associations between the LEMOCOT score, parameters of error and performance-based measures of lower-extremity impairment and gait were tested.

Methods

Twenty PwS (age: 62 ± 11.8 years, time after stroke onset: 84 ± 83 days; lower extremity Fugl-Meyer: 30.2 ± 3.7) and 20 healthy controls (age: 42 ± 15.8 years) participated in this cross-sectional exploratory study. Participants were instructed to move their big toe as fast and accurately as possible between targets marked on an electronic mat equipped with force sensors (Zebris FDM-T, 60 Hz). We extracted the contact surface area of each touch, from which the endpoint location, the center of pressure (COP), and the distance between them were computed. In addition, the absolute and variable error were calculated.

Results

PwS touched the targets with greater foot surface and demonstrated a greater distance between the endpoint location and the location of the COP. After controlling for the number of in-target touches, greater absolute and variable errors of the endpoint were observed in the paretic leg than in the non-paretic leg and the legs of controls. Also, the COP variable error differentiated between the paretic, non-paretic, and control legs and this parameter was independent of in-target counts. Negative correlations with moderate effect size were found between the Fugl Meyer assessment and the error parameters.

Conclusions

PwS demonstrated lower performance in all outcome measures than did controls. Several parameters of error indicated differences between legs (paretic leg, non-paretic leg and controls) and were independent of in-target touch counts, suggesting they may reflect motor deficits that are not identified by the traditional LEMOCOT score.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00950-z.

The impact of experimental pain on shoulder movement during an arm elevated reaching task in a virtual reality environment

BACKGROUND

People with chronic shoulder pain have been shown to present with motor adaptations during arm movements. These adaptations may create abnormal physical stress on shoulder tendons and muscles. However, how and why these adaptations develop from the acute stage of pain is still not well-understood.

OBJECTIVE

To investigate motor adaptations following acute experimental shoulder pain during upper limb reaching.

METHODS

Forty participants were assigned to the Control or Pain group. They completed a task consisting of reaching targets in a virtual reality environment at three time points: (1) baseline (both groups pain-free), (2) experimental phase (Pain group experiencing acute shoulder pain induced by injecting hypertonic saline into subacromial space), and (3) Post experimental phase (both groups pain-free). Electromyographic (EMG) activity, kinematics, and performance data were collected.

RESULTS

The Pain group showed altered movement planning and execution as shown by a significant increased delay to reach muscles EMG peak and a loss of accuracy, compared to controls that have decreased their mean delay to reach muscles peak and improved their movement speed through the phases. The Pain group also showed protective kinematic adaptations using less shoulder elevation and elbow flexion, which persisted when they no longer felt the experimental pain.

CONCLUSION

Acute experimental pain altered movement planning and execution, which affected task performance. Kinematic data also suggest that such adaptations may persist over time, which could explain those observed in chronic pain populations.

Exoskeleton-Assisted Anthropomorphic Movement Training (EAMT) for Poststroke Upper Limb Rehabilitation: A Pilot Randomized Controlled Trial

OBJECTIVE

To investigate the feasibility of exoskeleton-assisted anthropomorphic movement training (EAMT) and its effects on upper extremity motor impairment, function, and kinematics after stroke.

DESIGN

A single-blind pilot randomized controlled trial.

SETTING

Stroke rehabilitation inpatient unit.

PARTICIPANTS

Participants with a hemiplegia (N=20) due to a first-ever, unilateral, subacute stroke who had a score of 8-47 on the Fugl-Meyer Assessment for Upper Extremity (FMA-UE).

INTERVENTIONS

The exoskeleton group received EAMT therapy that provided task-specific training under anthropomorphic trajectories and postures. The control group received conventional upper limb therapy. For both groups, therapy was delivered at the same intensity, frequency, and duration: 45 minutes daily, 5 days per week, for 4 weeks.

MAIN OUTCOME MEASURES

Primary outcome: feasibility analysis.

SECONDARY OUTCOMES

FMA-UE, Action Research Arm Test (ARAT), modified Barthel Index (MBI), and kinematic metrics during exoskeleton therapy.

RESULTS

Twenty participants with subacute stroke were recruited and completed all therapy sessions. EAMT therapy was feasible and acceptable for the participants. The recruitment rate, retention rate, and number of therapists required for EAMT therapy were acceptable compared with other robotic trials. EAMT was determined to be safe, as no adverse event occurred except tolerable muscle fatigue in 2 participants. There were significant between-group differences in the change scores of FMA-UE (difference, 4.30 points; P=.04) and MBI (difference, 8.70 points; P=.03) in favor of EAMT therapy. No significant between-group difference was demonstrated for the change scores of ARAT (P=.18). Participants receiving EAMT showed significant improvements in kinematic metrics after treatment (P<.01).

CONCLUSIONS

Our results indicate that EAMT is a feasible approach and may improve upper extremity motor impairment, activities of daily living, and kinematics after stroke. However, fully powered randomized controlled trials are warranted to confirm the results of this pilot study and explore the underlying mechanisms by which EAMT therapy might work.

Validity, reliability, and sensitivity to motor impairment severity of a multi-touch app designed to assess hand mobility, coordination, and function after stroke

BACKGROUND

The assessment of upper-limb motor impairments after stroke is usually performed using clinical scales and tests, which may lack accuracy and specificity and be biased. Although some instruments exist that are capable of evaluating hand functions and grasping during functional tasks, hand mobility and dexterity are generally either not specifically considered during clinical assessments or these examinations lack accuracy. This study aimed to determine the convergent validity, reliability, and sensitivity to impairment severity after a stroke of a dedicated, multi-touch app, named the Hand Assessment Test.

METHODS

The hand mobility, coordination, and function of 88 individuals with stroke were assessed using the app, and their upper-limb functions were assessed using the Fugl-Meyer Assessment for Upper Extremity, the Jebsen-Taylor Hand Function Test, the Box and Block Test, and the Nine Hole Peg Test. Twenty-three participants were further considered to investigate inter- and intra-rater reliability, standard error of measurement, and the minimal detectable change threshold of the app. Finally, participants were categorized according to motor impairment severity and the sensitivity of the app relative to these classifications was investigated.

RESULTS

Significant correlations, of variable strengths, were found between the measurements performed by the app and the clinical scales and tests. Variable reliability, ranging from moderate to excellent, was found for all app measurements. Exercises that involved tapping and maximum finger-pincer grasp were sensitive to motor impairment severity.

CONCLUSIONS

The convergent validity, reliability, and sensitivity to motor impairment severity of the app, especially of those exercises that involved tapping and the maximum extension of the fingers, together with the widespread availability of the app, could support the use of this and similar apps to complement conventional clinical assessments of hand function after stroke.

Fatigue, induced via repetitive upper-limb motor tasks, influences trunk and shoulder kinematics during an upper limb reaching task in a virtual reality environment

BACKGROUND

Efficient shoulder movement depends on the ability of central nervous system to integrate sensory information and to create an appropriate motor command. Various daily encountered factors can potentially compromise the execution of the command, such as fatigue. This study explored how fatigue influences shoulder movements during upper limb reaching.

METHODS

Forty healthy participants were randomly assigned to one of two groups: Control or Fatigue Group. All participants completed an upper limb reaching task at baseline and post-experimental, during which they reached four targets located at 90° of shoulder abduction, 90° external rotation at 90° abduction, 120° scaption, and 120° flexion in a virtual reality environment. Following the baseline phase, the Fatigue Group completed a shoulder fatigue protocol, while Controls took a 10-minute break. Thereafter, the reaching task was repeated. Upper limb kinematic (joint angles and excursions) and spatiotemporal (speed and accuracy) data were collected during the reaching task. Electromyographic activity of the anterior and middle deltoids were also collected to characterize fatigue. Two-way repeated-measures ANOVA were performed to determine the effects of Time, Group and of the interaction between these factors.

RESULTS

The Fatigue group showed decreased mean median power frequency and increased electromyographic amplitudes of the anterior deltoid (p < 0.05) following the fatigue protocol. Less glenohumeral elevation, increased trunk flexion and rotation and sternoclavicular elevation were also observed in the Fatigue group (Group x Time interaction, p < 0.05). The Control group improved their movement speed and accuracy in post-experimental phase, while the Fatigue group showed a decrease of movement speed and no accuracy improvement (Group x Time interaction, p < 0.05).

CONCLUSION

In a fatigued state, changes in movement strategy were observed during the reaching task, including increased trunk and sternoclavicular movements and less glenohumeral movement. Performance was altered as shown by the lack of accuracy improvement over time and a decrease in movement speed in the Fatigue group.

Shoulder function after constraint-induced movement therapy assessed with 3D kinematics and clinical and patient reported outcomes: A prospective cohort study

INTRODUCTION

We hypothesised that reduced shoulder function post stroke improves during constraint-induced movement therapy and that improvement in scapula upward rotation measured with three-dimensional kinematics is associated with improvements in clinical and patient reported outcomes.

METHODS

Thirty-seven patients were tested pre and post constraint-induced movement therapy and again at three-month follow-up. Kinematic outcome measures - with scapula upward rotation as the primary outcome - during tasks 5 (ReachLow) and 6 (ReachHigh) from the Wolf Motor Function Test were included together with clinical and patient reported outcomes. Changes in outcome measures were analysed with linear mixed models and logistic regression analysis.

FINDINGS

Scapula upward rotation was reduced from 16.2° pre intervention through 15.9° post intervention to 15.6° at three-month follow-up during ReachHigh. Statistically significant reductions of <2° were also found for shoulder flexion during ReachLow and trunk lateral flexion during ReachHigh. The clinical and patient reported outcomes showed improvements post constraint-induced movement therapy, and at follow-up, the outcomes resembled post values.

INTERPRETATION

The minimal improvements in selected 3D kinematic measures of upper extremity movements did not reflect any clinically meaningful changes. Therefore, the clinical and patient reported improvements could not be related to restitution of shoulder function.

Measures of Interjoint Coordination Post-stroke Across Different Upper Limb Movement Tasks

Background: Deficits in interjoint coordination, such as the inability to move out of synergy, are frequent symptoms in stroke subjects with upper limb impairments that hinder them from regaining normal motor function. Kinematic measurements allow a fine-grained assessment of movement pathologies, thereby complementing clinical scales, like the Fugl–Meyer Motor Assessment of the Upper Extremity (FMMA-UE). The study goal was to investigate the effects of the performed task, the tested arm, the dominant affected hand, upper limb function, and age on spatiotemporal parameters of the elbow, shoulder, and trunk. The construct validity of the metrics was examined by relating them with each other, the FMMA-UE, and its arm section.

Methods: This is a cross-sectional observational study including chronic stroke patients with mild to moderate upper limb motor impairment. Kinematic measurements were taken using a wearable sensor suit while performing four movements with both upper limbs: (1) isolated shoulder flexion, (2) pointing, (3) reach-to-grasp a glass, and (4) key insertion. The kinematic parameters included the joint ranges of shoulder abduction/adduction, shoulder flexion/extension, and elbow flexion/extension; trunk displacement; shoulder–elbow correlation coefficient; median slope; and curve efficiency. The effects of the task and tested arm on the metrics were investigated using a mixed-model analysis. The validity of metrics compared to clinically measured interjoint coordination (FMMA-UE) was done by correlation analysis.

Results: Twenty-six subjects were included in the analysis. The movement task and tested arm showed significant effects (p < 0.05) on all kinematic parameters. Hand dominance resulted in significant effects on shoulder flexion/extension and curve efficiency. The level of upper limb function showed influences on curve efficiency and the factor age on median slope. Relations with the FMMA-UE revealed the strongest and significant correlation for curve efficiency (r = 0.75), followed by shoulder flexion/extension (r = 0.68), elbow flexion/extension (r = 0.53), and shoulder abduction/adduction (r = 0.49). Curve efficiency additionally correlated significantly with the arm subsection, focusing on synergistic control (r = 0.59).

Conclusion: The kinematic parameters of the upper limb after stroke were influenced largely by the task. These results underpin the necessity to assess different relevant functional movements close to real-world conditions rather than relying solely on clinical measures.

Study Registration: clinicaltrials.gov, identifier NCT03135093 and BASEC-ID 2016-02075.

Development of a Comprehensive Outcome Measure for Motor Coordination, Step 2: Reliability and Construct Validity in Chronic Stroke Patients

BACKGROUND

A comprehensive scale assessing motor coordination of multiple body segments was developed using a 3-phase content validation process. The Comprehensive Coordination Scale (CCS) evaluates motor coordination defined as the ability to produce context-dependent movements of multiple effectors in both spatial and temporal domains. The scale assesses motor coordination in individuals with neurological injuries at 2 levels of movement description: the motor performance level describes end point movements (ie, hand, foot), and the movement quality level describes limb joints/trunk movements contributing to end point movement.

OBJECTIVE

To determine measurement properties of the scale in people with chronic stroke.

METHODS

Standardized approaches determined the internal consistency (factor loadings), intrarater and interrater reliability (interclass correlation coefficient), measurement error (SEM; minimal detectable change [MDC]), construct validity, and interpretability (ie, ceiling and floor effects) of the CCS.

RESULTS

Data from 30 patients with chronic stroke were used for the analysis. The internal consistency of the scale was high (0.94), and the scale consisted of separate factors characterizing end point motor performance and movement quality. Intrarater (intraclass correlation coefficient [ICC] = 0.97-0.97) and interrater (ICC=0.76-0.98) reliability of the whole scale and subscales were good to excellent. The CCS had an SEM of 1.80 points (total score = 69 points) and an MDC₉₅ of 4.98 points. The CCS total score was related to Fugl-Meyer Assessment total and motor scores and had no ceiling or floor effects.

CONCLUSIONS

The CCS scale has strong measurement properties and may be a useful measure of spatial and temporal coordination deficits in chronic stroke survivors.

Development of a Comprehensive Outcome Measure for Motor Coordination; Step 1: Three-Phase Content Validity Process

BACKGROUND

Motor coordination, the ability to produce context-dependent organized movements in spatial and temporal domains, is impaired after neurological injuries. Outcome measures assessing coordination mostly quantify endpoint performance variables (ie, temporal qualities of whole arm movement) but not movement quality (ie, trunk and arm joint displacements).

OBJECTIVE

To develop an outcome measure to assess coordination of multiple body segments at both endpoint trajectory and movement quality levels, based on observational kinematics, in adults with neurological injuries.

METHODS

A 3-phase study was used to develop the Comprehensive Coordination Scale (CCS): instrument development, Delphi process, and focus group meeting. The CCS was constructed from common tests used in clinical practice and research. Rating scales for different behavioral elements were developed to guide analysis. For content validation, 8 experts (ie, neurological clinicians/researchers) answered questionnaires about relevance, comprehension, and feasibility of each test and rating scale. A focus group conducted with 6 of 8 experts obtained consensus on rating scale and instruction wording, and identified gaps. Three additional experts reviewed the revised CCS content to obtain a final version.

RESULTS

Experts identified a gap regarding assessment of hand/finger coordination. The CCS final version is composed of 6 complementary tests of coordination: finger-to-nose, arm-trunk, finger, lower extremity, and 2- and 4-limb interlimb coordination. Constructs include spatial and temporal variables totaling 69 points. Higher scores indicate better performance.

CONCLUSIONS

The CCS may be an important, understandable and feasible outcome measure to assess spatial and temporal coordination. CCS measurement properties are presented in the companion article.

Movement Quality: A Novel Biomarker Based on Principles of Neuroscience

A major problem in neurorehabilitation is the lack of objective outcomes to measure movement quality. Movement quality features, such as coordination and stability, are essential for everyday motor actions. These features allow reacting to continuously changing environment or to resist external perturbations. Neurological disorders affect movement quality, leading to functionally impaired movements. Recent findings suggest that the central nervous system organizes motor elements (eg, muscles, joints, fingers) into task-specific ensembles to stabilize motor tasks performance. A method to quantify this feature has been previously developed based on the uncontrolled manifold (UCM) hypothesis. UCM quantifies movement quality in a spatial-temporal domain using intertrial analysis of covariation between motor elements. In this point-of-view article, we first describe major obstacles (eg, the need for group analysis) that interfere with UCM application in clinical settings. Then, we propose a process of quantifying movement quality for a single individual with a novel use of bootstrapping simulations and UCM analysis. Finally, we reanalyze previously published data from individuals with neurological disorders performing a wide range of motor tasks, that is, multi-digit pressing and postural balance tasks. Our method allows one to assess motor quality impairments in a single individual and to detect clinically important motor behavior changes. Our solution may be incorporated into a clinical setting to assess sensorimotor impairments, evaluate the effects of specific neurological treatments, or track movement quality recovery over time. We also recommended the proposed solution to be used jointly with a typical statistical analysis of UCM parameters in cohort studies.

A Reaching Performance Scale for 2 Wolf Motor Function Test Items

OBJECTIVE

To adapt the Reaching Performance Scale for Stroke (RPSS) for the Wolf Motor Function Test (WMFT) "Lift Can" (Can) and "Hand to Box" (Box) items.

DESIGN

Retrospective analysis of video-recorded WMFT assessment performed by 3 raters on 2 occasions.

SETTING

Not applicable.

PARTICIPANTS

Participants (N=29) with mild to moderate upper extremity impairment less than 3 months after stroke.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Inter- and intra-rater agreement, concurrent validity of WMFT-RPSS.

RESULTS

Mean ± SD inter-rater Gwet's agreement coefficient (AC₂) was 0.61±0.05 for Can WMFT-RPSS and 0.56 (0.03) for Box. Mean ± SD intra-rater AC₂ for Can was 0.63±0.05 and 0.70±0.04 for Box. WMFT-RPSS Can and Box scores correlated with log mean WMFT time (C, -0.73; B, -0.48), Functional Ability Scale (C, 0.87; B, 0.62), Upper Extremity Fugl-Meyer Motor Score (C, 0.69; B, 0.51), and item movement rate (C, 0.74; B, 0.71) (P<.05 for all). Mean ± SD WMFT-RPSS score across the 29 participants was 12.7±3.5 for Can (max score, 19) and 11.4±3.0 for Box (max score, 16).

CONCLUSIONS

WMFT-RPSS demonstrated moderate intra-rater and weak-to-moderate inter-rater agreement for individuals with mild-moderate impairment. For construct validity, Can and Box WMFT-RPSS were significantly correlated with 4 standardized measures. Average WMFT-RPSS scores revealed that some participants may have relied on compensatory movements to complete the task, a revelation not discernable from movement rate alone. The WMFT-RPSS is potentially useful as a valid and reliable tool to examine longitudinal changes in movement quality after stroke.

Stability of reaching during standing in stroke

Reaching from standing requires simultaneous adjustments of focal and postural task elements. We investigated the ability of people with stroke to stabilize the endpoint trajectory while maintaining balance during standing reaches. Nineteen stroke and 11 age-equivalent healthy subjects reached toward a target (n = 30 trials) located beyond arm length from standing. Endpoint and center-of-mass (COM) trajectories were analyzed using the uncontrolled manifold (UCM) approach, with segment angles as elemental variables. A synergy index (SI) represented the normalized difference between segment angle combinations, leading to endpoint or COM trajectory stabilization (V_UCM) and lack of stabilization (in an orthogonal space; V_ORT). A higher SI reflects greater stability. In both groups, the endpoint SI (SI_END) decreased in parallel with endpoint velocity and returned close to baseline at the end of the movement. The range of SI_END was significantly greater in stroke (median: 0.87; QR:0.54) compared with healthy subjects (median: 0.58; QR: 0.33; P = 0.009). In both groups, the lowest SI_END occurred at the endpoint peak velocity, whereas the minimal SI_END of the stroke group (median: 0.51; QR:0.41) was lower than the healthy group (median: 0.25; QR: 0.50; P = 0.033). The COM SI (SI_COM) remained stable in both groups (~0.8). The maintenance of a high SI_COM despite a large reduction of SI_END in stroke subjects suggests that kinematic redundancy was effectively used to stabilize the COM position, but less so for endpoint position stabilization. Both focal and postural task elements should be considered when analyzing whole body reaching deficits in patients with stroke.NEW & NOTEWORTHY Reaching from standing requires simultaneous adjustments of endpoint and center-of-mass (COM) positions. We used uncontrolled manifold analysis to investigate the impact of stroke on the ability to use kinematic redundancy in this task. Our results showed that COM position was stabilized, whereas endpoint trajectory was more variable in stroke than healthy subjects. Enhancing the capacity to meet multiple task goals may be beneficial for motor recovery after stroke.

Motor-Equivalent Intersegmental Coordination Is Impaired in Chronic Stroke

Background. Kinematic abundance permits using different movement patterns for task completion. Individuals poststroke may take advantage of abundance by using compensatory trunk displacement to overcome upper limb (UL) movement deficits. However, movement adaptation in tasks requiring specific intersegment coordination may remain limited. Objective. We tested movement adaptation in both arms of individuals with chronic stroke (n = 16) and nondominant arms of controls (n = 12) using 2 no-vision reaching tasks involving trunk movement (40 trials/arm). Methods. In the "stationary hand task" (SHT), subjects maintained the hand motionless over a target while leaning the trunk forward. In the "reaching hand task" (RHT), subjects reached to the target while leaning forward. For both tasks, trunk movement was unexpectedly blocked in 40% of trials to assess the influence of trunk movement on adaptive arm positioning or reaching. UL sensorimotor impairment, activity, and sitting balance were assessed in the stroke group. The primary outcome measure for SHT was gain (g), defined as the extent to which trunk displacement contributing to hand motion was offset by appropriate changes in UL movements (g = 1: complete compensation) and endpoint deviation for RHT. Results. Individuals poststroke had lower gains and greater endpoint deviation using the more-affected compared with less-affected UL and controls. Those with less sensorimotor impairment, greater activity levels, and better sitting balance had higher gains and smaller endpoint deviations. Lower gains were associated with diminished UL adaptability. Conclusions. Tests of condition-specific adaptability of interjoint coordination may be used to measure UL adaptability and changes in adaptability with treatment.

Kinematic Synergy of Multi-DoF Movement in Upper Limb and Its Application for Rehabilitation Exoskeleton Motion Planning

It is important for rehabilitation exoskeletons to move with a spatiotemporal motion patterns that well match the upper-limb joint kinematic characteristics. However, few efforts have been made to manipulate the motion control based on human kinematic synergies. This work analyzed the spatiotemporal kinematic synergies of right arm reaching movement and investigated their potential usage in upper limb assistive exoskeleton motion planning. Ten right-handed subjects were asked to reach 10 target button locations placed on a cardboard in front. The kinematic data of right arm were tracked by a motion capture system. Angular velocities over time for shoulder flexion/extension, shoulder abduction/adduction, shoulder internal/external rotation, and elbow flexion/extension were computed. Principal component analysis (PCA) was used to derive kinematic synergies from the reaching task for each subject. We found that the first four synergies can explain more than 94% of the variance. Moreover, the joint coordination patterns were dynamically regulated over time as the number of kinematic synergy (PC) increased. The synergies with different order played different roles in reaching movement. Our results indicated that the low-order synergies represented the overall trend of motion patterns, while the high-order synergies described the fine motions at specific moving phases. A 4-DoF upper limb assistive exoskeleton was modeled in SolidWorks to simulate assistive exoskeleton movement pattern based on kinematic synergy. An exoskeleton Denavit-Hartenberg (D-H) model was established to estimate the exoskeleton moving pattern in reaching tasks. The results further confirmed that kinematic synergies could be used for exoskeleton motion planning, and different principal components contributed to the motion trajectory and end-point accuracy to some extent. The findings of this study may provide novel but simplified strategies for the development of rehabilitation and assistive robotic systems approximating the motion pattern of natural upper-limb motor function.

Relationship Between Spasticity and Upper-Limb Movement Disorders in Individuals With Subacute Stroke Using Stochastic Spatiotemporal Modeling

BACKGROUND

Spasticity is common in patients with stroke, yet current quantification methods are insufficient for determining the relationship between spasticity and voluntary movement deficits. This is partly a result of the effects of spasticity on spatiotemporal characteristics of movement and the variability of voluntary movement. These can be captured by Gaussian mixture models (GMMs).

OBJECTIVES

To determine the influence of spasticity on upper-limb voluntary motion, as assessed by the bidirectional Kullback-Liebler divergence (BKLD) between motion GMMs.

METHODS

A total of 16 individuals with subacute stroke and 13 healthy aged-equivalent controls reached to grasp 4 targets (near-center, contralateral, far-center, and ipsilateral). Two-dimensional GMMs (angle and time) were estimated for elbow extension motion. BKLD was computed for each individual and target, within the control group and between the control and stroke groups. Movement time, final elbow angle, average elbow velocity, and velocity smoothness were computed.

RESULTS

Between-group BKLDs were much larger than within control-group BKLDs. Between-group BKLDs for the near-center target were lower than those for the far-center and contralateral targets, but similar to that for the ipsilateral target. For those with stroke, the final angle was lower for the near-center target, and the average velocity was higher. Velocity smoothness was lower for the near-center than for the ipsilateral target. Elbow flexor and extensor passive muscle resistance (Modified Ashworth Scale) strongly explained BKLD values.

CONCLUSIONS

Results support the view that individuals with poststroke spasticity have a velocity-dependent reduction in active elbow joint range and that BKLD can be used as an objective measure of the effects of spasticity on reaching kinematics.