Movement Kinematics During a Drinking Task Are Associated With the Activity Capacity Level After Stroke

Feature analysis of joint motion in paralyzed and non-paralyzed upper limbs while reaching the occiput: A cross-sectional study in patients with mild hemiplegia

The reaching motion to the back of the head with the hand is an important movement for daily living. The scores of upper limb function tests used in clinical practice alone are difficult to use as a reference when planning exercises for movement improvements. This cross-sectional study aimed to clarify in patients with mild hemiplegia the kinematic characteristics of paralyzed and non-paralyzed upper limbs reaching the occiput. Ten patients with post-stroke hemiplegia who attended the Department of Rehabilitation Medicine of the Jikei University Hospital and met the eligibility criteria were included. Reaching motion to the back of the head by the participants' paralyzed and non-paralyzed upper limbs was measured using three-dimensional motion analysis, and the motor time, joint angles, and angular velocities were calculated. Repeated measures multivariate analysis of covariance was performed on these data. After confirming the fit to the binomial logistic regression model, the cutoff values were calculated using receiver operating characteristic curves. Pattern identification using random forest clustering was performed to analyze the pattern of motor time and joint angles. The cutoff values for the movement until the hand reached the back of the head were 1.6 s for the motor time, 55° for the maximum shoulder joint flexion angle, and 145° for the maximum elbow joint flexion angle. The cutoff values for the movement from the back of the head to the hand being returned to its original position were 1.6 s for the motor time, 145° for the maximum elbow joint flexion angle, 53°/s for the maximum angular velocity of shoulder joint abduction, and 62°/s for the maximum angular velocity of elbow joint flexion. The numbers of clusters were three, four, and four for the outward non-paralyzed side, outward and return paralyzed side, and return non-paralyzed side, respectively. The findings obtained by this study can be used for practice planning in patients with mild hemiplegia who aim to improve the reaching motion to the occiput.

Upper limb movement quality measures: comparing IMUs and optical motion capture in stroke patients performing a drinking task

Introduction

Clinical assessment of upper limb sensorimotor function post-stroke is often constrained by low sensitivity and limited information on movement quality. To address this gap, recent studies proposed a standardized instrumented drinking task, as a representative daily activity combining different components of functional arm use. Although kinematic movement quality measures for this task are well-established, and optical motion capture (OMC) has proven effective in their measurement, its clinical application remains limited. Inertial Measurement Units (IMUs) emerge as a promising low-cost and user-friendly alternative, yet their validity and clinical relevance compared to the gold standard OMC need investigation.

Method

In this study, we conducted a measurement system comparison between IMUs and OMC, analyzing 15 established movement quality measures in 15 mild and moderate stroke patients performing the drinking task, using five IMUs placed on each wrist, upper arm, and trunk.

Results

Our findings revealed strong agreement between the systems, with 12 out of 15 measures demonstrating clinical applicability, evidenced by Limits of Agreement (LoA) below the Minimum Clinically Important Differences (MCID) for each measure.

Discussion

These results are promising, suggesting the clinical applicability of IMUs in quantifying movement quality for mildly and moderately impaired stroke patients performing the drinking task.

Age- and sex-related differences in upper-body joint and endpoint kinematics during a drinking task in healthy adults

Background

The objective kinematic assessments of activities of daily living are desired. However, the limited knowledge regarding age- and sex-related differences prevents the adaptation of these measurements to clinical settings and in-home exercises. Therefore, this study aimed to determine the effects of age and sex on joint and endpoint kinematics during a common activity of daily living, specifically, drinking from a glass.

Methods

In total, 32 healthy adults (18 males and 14 females) aged 22-77 years performed a drinking task comprising reaching for a glass, bringing it forward and sipping, returning it, and placing the hand back to the starting position, which was recorded using a three-dimensional motion-capturing system. A two-way analysis of variance was used to statistically compare joint angles at five different time points and endpoint kinematic variables in the four drinking phases between older and younger age groups and sexes.

Results

Wrist radial deviation was greater in older adults than in younger participants at all five different time points (F = 5.16-7.34, p ≤ 0.03, η2 = 0.14-0.21). Moreover, lesser shoulder abduction and greater shoulder internal rotation and forearm pronation when moving and returning the hand to the starting position were observed in the female group than in the male group (F = 4.21-20.03, p ≤ 0.0497, η2 = 0.13-0.41). Trunk flexion was lower in the female group than in the male group at all time points (F = 4.25-7.13, p ≤ 0.0485, η2 = 0.12-0.19). Regarding endpoint kinematics, the performance time in the reaching phase was longer in older adults than in younger individuals (F = 4.96, p = 0.03, η2 = 0.14). Furthermore, a shorter time while returning the hand to the starting position was observed in the female group than in the male group (F = 9.55, p < 0.01, η2 = 0.22).

Conclusions

The joint kinematics of drinking were partially characterized by an age effect, whereas endpoint kinematics were scattered in all drinking phases. Sex-related effects in most upper-body motions and postures may cause rapid motions in females. Therefore, clinicians could use this knowledge for precise assessments and to suggest feasible in-home exercises.

Effects of bihemispheric transcranial direct current stimulation on motor recovery in subacute stroke patients: a double-blind, randomized sham-controlled trial

BACKGROUND

Bihemispheric transcranial direct current stimulation (tDCS) of the primary motor cortex (M1) can simultaneously modulate bilateral corticospinal excitability and interhemispheric interaction. However, how tDCS affects subacute stroke recovery remains unclear. We investigated the effects of bihemispheric tDCS on motor recovery in subacute stroke patients.

METHODS

We enrolled subacute inpatients who had first-ever ischemic stroke at subcortical regions and moderate-to-severe baseline Fugl-Meyer Assessment of Upper Extremity (FMA-UE) score 2-56. Participants between 14 and 28 days after stroke were double-blind, randomly assigned (1:1) to receive real (n = 13) or sham (n = 14) bihemispheric tDCS (with ipsilesional M1 anode and contralesional M1 cathode, 20 min, 2 mA) during task practice twice daily for 20 sessions in two weeks. Residual integrity of the ipsilesional corticospinal tract was stratified between groups. The primary efficacy outcome was the change in FMA-UE score from baseline (responder as an increase ≥ 10). The secondary measures included changes in the Action Research Arm Test (ARAT), FMA-Lower Extremity (FMA-LE) and explorative resting-state MRI functional connectivity (FC) of target regions after intervention and three months post-stroke.

RESULTS

Twenty-seven participants completed the study without significant adverse effects. Nineteen patients (70%) had no recordable baseline motor-evoked potentials (MEP-negative) from the paretic forearm. Compared with the sham group, the real tDCS group showed enhanced improvement of FMA-UE after intervention (p < 0.01, effect size η² = 0.211; responder rate: 77% vs. 36%, p = 0.031), which sustained three months post-stroke (p < 0.01), but not ARAT. Interestingly, in the MEP-negative subgroup analysis, the FMA-UE improvement remained but delayed. Additionally, the FMA-LE improvement after real tDCS was not significantly greater until three months post-stroke (p < 0.01). We found that the individual FMA-UE improvements after real tDCS were associated with bilateral intrahemispheric, rather than interhemispheric, FC strengths in the targeted cortices, while the improvements after sham tDCS were associated with predominantly ipsilesional FC changes after adjustment for age and sex (p < 0.01).

CONCLUSIONS

Bihemispheric tDCS during task-oriented training may facilitate motor recovery in subacute stroke patients, even with compromised corticospinal tract integrity. Further studies are warranted for tDCS efficacy and network-specific neuromodulation.

TRIAL REGISTRATION

This study is registered with ClinicalTrials.gov: (ID: NCT02731508).

Clinical interpretation and cutoff scores for manual ability measured by the ABILHAND questionnaire in people with stroke

BACKGROUND

The ABILHAND questionnaire is recommended to assess perceived manual ability after stroke; however, more knowledge on interpretability is needed to improve the clinical applicability.

OBJECTIVES

To determine clinically meaningful cutoff scores for different levels of perceived manual ability, assessed by ABILHAND, corresponding to established observed and perceived upper extremity assessments post stroke.

METHODS

This cross-sectional study, part of the Stroke Arm Longitudinal Study (SALGOT) at the University of Gothenburg, included 80 participants with upper extremity impairments after stroke. The self-reported upper extremity functioning was assessed with ABILHAND and Stroke Impact Scale Hand (SIS Hand), and the observed functioning was assessed by Fugl-Meyer Assessment for Upper Extremity (FMA-UE) and Action Research Arm Test (ARAT) at 3 months after stroke. Receiver operating characteristic curve, sensitivity, and specificity analyses were used to determine the cutoffs.

RESULTS

The overall discriminating accuracy was excellent (AUC > 0.90) for most of the cutoffs and sensitivity and specificity values ranged from 0.73 to 1.0. The ABILHAND cutoff score 1.78 discriminated well between low and good functioning resulting in a 95% match with SIS Hand and 87.5% match with ARAT and FMA-UE.

CONCLUSIONS

The determined cutoff scores of the ABILHAND, validated through established upper extremity assessments, will provide a useful tool to clinicians when interpreting the logit scores and when selecting individualized treatment options. ABILHAND matched well with self-reported SIS Hand, but discrepancies found with observed scales implies that self-perceived assessments should be complemented with observed assessments.

Psychometric Properties of a New Measure of Upper Limb Performance in Post-Stroke Individuals: Trunk-Based Index of Performance

BACKGROUND

Several measures of upper limb (UL) motor tasks have been developed to characterize recovery. However, UL performance and movement quality measures in isolation may not provide a true profile of functional recovery.

OBJECTIVE

To investigate the measurement properties of a new trunk-based Index of Performance (IPt) of the UL combining endpoint performance (accuracy and speed) and movement quality (trunk displacement) in stroke.

METHODS

Participants with stroke (n = 25, mean time since stroke: 18.7 ± 17.2 months) performed a reaching task over 3 evaluation sessions. The IPt was computed based on Fitts' Law that incorporated endpoint accuracy and speed corrected by the amount of trunk displacement. Test-retest reliability was analyzed using intraclass correlation coefficient (ICC) and Bland-Altman plots. Standard error of measurement (SEM) and Minimal Detectable Change (MDC) were determined. Validity was investigated through the relationship between IPt, Fugl-Meyer Assessment (FMA-UE), and Action Research Arm Test (ARAT), as well as the ability of IPt to distinguish between levels of UL motor impairment severity.

RESULTS

Test-retest reliability was excellent (ICC = .908, 95% CI: 0.807-0.96). Bland-Altman did not show systematic differences. SEM and MDC₉₅ were 14% and 39%, respectively. Construct validity was satisfactory. The IPt showed low-to-moderate relationships with FMA-UE (R² ranged from .236 to .428) and ARAT (R² ranged from .277 to .306). IPt scores distinguished between different levels of UL severity.

CONCLUSIONS

The IPt showed evidence of good reliability, and initial validity. The IPt may be a promising tool for research and clinical settings. Further research is warranted to investigate its validity with additional comparator instruments.

Using Wearable Inertial Sensors to Estimate Clinical Scores of Upper Limb Movement Quality in Stroke

Neurorehabilitation is progressively shifting from purely in-clinic treatment to therapy that is provided in both clinical and home-based settings. This transition generates a pressing need for assessments that can be performed across the entire continuum of care, a need that might be accommodated by application of wearable sensors. A first step toward ubiquitous assessments is to augment validated and well-understood standard clinical tests. This route has been pursued for the assessment of motor functioning, which in clinical research and practice is observation-based and requires specially trained personnel. In our study, 21 patients performed movement tasks of the Action Research Arm Test (ARAT), one of the most widely used clinical tests of upper limb motor functioning, while trained evaluators scored each task on pre-defined criteria. We collected data with just two wrist-worn inertial sensors to guarantee applicability across the continuum of care and used machine learning algorithms to estimate the ARAT task scores from sensor-derived features. Tasks scores were classified with approximately 80% accuracy. Linear regression between summed clinical task scores (across all tasks per patient) and estimates of sum task scores yielded a good fit (R 2 = 0.93; range reported in previous studies: 0.61-0.97). Estimates of the sum scores showed a mean absolute error of 2.9 points, 5.1% of the total score, which is smaller than the minimally detectable change and minimally clinically important difference of the ARAT when rated by a trained evaluator. We conclude that it is feasible to obtain accurate estimates of ARAT scores with just two wrist worn sensors. The approach enables administration of the ARAT in an objective, minimally supervised or remote fashion and provides the basis for a widespread use of wearable sensors in neurorehabilitation.

Kinematic analysis of activities of daily living performance in frail elderly

Background

Frailty is accompanied by limitations of activities of daily living (ADL) and frequently associated with reduced quality of life, institutionalization, and higher health care costs. Despite the importance of ADL performance for the consequence of frailty, movement analyses based on kinematic markers during the performance of complex upper extremity-based manual ADL tasks in frail elderly is still pending.

The main objective of this study was to evaluate if ADL task performance of two different tasks in frail elderlies can be assessed by an activity measurement based on an acceleration sensor integrated into a smartwatch, and further to what degree kinematic parameters would be task independent.

Methods

ADL data was obtained from twenty-seven elderly participants (mean age 81.6 ± 7.0 years) who performed two ADL tasks. Acceleration data of the dominant hand was collected using a smartwatch. Participants were split up in three groups, F (frail, n = 6), P (pre-frail, n = 13) and R (robust, n = 8) according to a frailty screening. A variety of kinematic measures were calculated from the vector product reflecting activity, agility, smoothness, energy, and intensity.

Results

Measures of agility, smoothness, and intensity revealed significant differences between the groups (effect sizes combined over tasks η²_p = 0.18 – 0.26). Smoothness was particularly affected by frailty in the tea making task, while activity, agility, a different smoothness parameter and two intensity measures were related to frailty in the gardening task. Four of nine parameters revealed good reliability over both tasks (r = 0.44 – 0.69). Multiple linear regression for the data combined across tasks showed that only the variability of the magnitude of acceleration peaks (agility) contributed to the prediction of the frailty score (R² = 0.25).

Conclusion

The results demonstrate that ADL task performance can be assessed by smartwatch-based measures and further shows task-independent differences between the three levels of frailty. From the pattern of impaired and preserved performance parameters across the tested tasks, we concluded that in persons with frailty ADL performance was more impaired by physiological deficiencies, i.e., physical power and endurance, than by cognitive functioning or sensorimotor control.

Usability of Functional Electrical Stimulation in Upper Limb Rehabilitation in Post-Stroke Patients: A Narrative Review

Stroke leads to significant impairment in upper limb (UL) function. The goal of rehabilitation is the reestablishment of pre-stroke motor stroke skills by stimulating neuroplasticity. Among several rehabilitation approaches, functional electrical stimulation (FES) is highlighted in stroke rehabilitation guidelines as a supplementary therapy alongside the standard care modalities. The aim of this study is to present a comprehensive review regarding the usability of FES in post-stroke UL rehabilitation. Specifically, the factors related to UL rehabilitation that should be considered in FES usability, as well a critical review of the outcomes used to assess FES usability, are presented. This review reinforces the FES as a promising tool to induce neuroplastic modifications in post-stroke rehabilitation by enabling the possibility of delivering intensive periods of treatment with comparatively less demand on human resources. However, the lack of studies evaluating FES usability through motor control outcomes, specifically movement quality indicators, combined with user satisfaction limits the definition of FES optimal therapeutical window for different UL functional tasks. FES systems capable of integrating postural control muscles involving other anatomic regions, such as the trunk, during reaching tasks are required to improve UL function in post-stroke patients.

European evidence-based recommendations for clinical assessment of upper limb in neurorehabilitation (CAULIN): data synthesis from systematic reviews, clinical practice guidelines and expert consensus

BACKGROUND

Technology-supported rehabilitation can help alleviate the increasing need for cost-effective rehabilitation of neurological conditions, but use in clinical practice remains limited. Agreement on a core set of reliable, valid and accessible outcome measures to assess rehabilitation outcomes is needed to generate strong evidence about effectiveness of rehabilitation approaches, including technologies. This paper collates and synthesizes a core set from multiple sources; combining existing evidence, clinical practice guidelines and expert consensus into European recommendations for Clinical Assessment of Upper Limb In Neurorehabilitation (CAULIN).

METHODS

Data from systematic reviews, clinical practice guidelines and expert consensus (Delphi methodology) were systematically extracted and synthesized using strength of evidence rating criteria, in addition to recommendations on assessment procedures. Three sets were defined: a core set: strong evidence for validity, reliability, responsiveness and clinical utility AND recommended by at least two sources; an extended set: strong evidence OR recommended by at least two sources and a supplementary set: some evidence OR recommended by at least one of the sources.

RESULTS

In total, 12 measures (with primary focus on stroke) were included, encompassing body function and activity level of the International Classification of Functioning and Health. The core set recommended for clinical practice and research: Fugl-Meyer Assessment of Upper Extremity (FMA-UE) and Action Research Arm Test (ARAT); the extended set recommended for clinical practice and/or clinical research: kinematic measures, Box and Block Test (BBT), Chedoke Arm Hand Activity Inventory (CAHAI), Wolf Motor Function Test (WMFT), Nine Hole Peg Test (NHPT) and ABILHAND; the supplementary set recommended for research or specific occasions: Motricity Index (MI); Chedoke-McMaster Stroke Assessment (CMSA), Stroke Rehabilitation Assessment Movement (STREAM), Frenchay Arm Test (FAT), Motor Assessment Scale (MAS) and body-worn movement sensors. Assessments should be conducted at pre-defined regular intervals by trained personnel. Global measures should be applied within 24 h of hospital admission and upper limb specific measures within 1 week.

CONCLUSIONS

The CAULIN recommendations for outcome measures and assessment procedures provide a clear, simple, evidence-based three-level structure for upper limb assessment in neurological rehabilitation. Widespread adoption and sustained use will improve quality of clinical practice and facilitate meta-analysis, critical for the advancement of technology-supported neurorehabilitation.

Kinematic descriptions of upper limb function using simulated tasks in activities of daily living after stroke

Assessment of upper limb function poststroke is critical for clinical management and determining the efficacy of interventions. We designed a unilateral upper limb task to simulate activities of daily living to examine how chronic stroke survivors manage reaching, grasping and handling skills simultaneously to perform the functional task using kinematic analysis. The aim of the study was to compare the motor strategies for performing a functional task between paretic and nonparetic arms. Sixteen chronic stroke survivors were instructed to control an ergonomic spoon to transfer liquid from a large bowl to a small bowl using paretic or nonparetic arm. Kinematic data were recorded using a Vicon motion capture system. Outcome measures included movement duration, relative timing, path length, joint excursions, and trial-to-trial variability. Results showed that movement duration, spoon path length, and trunk path length increased significantly when participants used paretic arm to perform the task. Participants tended to reduce shoulder and elbow excursions, and increase trunk excursions to perform the task with paretic arm and altered the relative timing of the task. Although participants used different motor strategies to perform the task with their paretic arms, we did not find the significant differences in trial-to trial variability of joint excursions between paretic and nonparetic arms. The results revealed differences in temporal and spatial aspects of motor strategies between paretic and nonparetic arms. Clinicians should explore the underlying causes of pathological movement patterns and facilitate preferred movement patterns of paretic arm.

Impairment and Compensation in Dexterous Upper-Limb Function After Stroke. From the Direct Consequences of Pyramidal Tract Lesions to Behavioral Involvement of Both Upper-Limbs in Daily Activities

Impairments in dexterous upper limb function are a significant cause of disability following stroke. While the physiological basis of movement deficits consequent to a lesion in the pyramidal tract is well demonstrated, specific mechanisms contributing to optimal recovery are less apparent. Various upper limb interventions (motor learning methods, neurostimulation techniques, robotics, virtual reality, and serious games) are associated with improvements in motor performance, but many patients continue to experience significant limitations with object handling in everyday activities. Exactly how we go about consolidating adaptive motor behaviors through the rehabilitation process thus remains a considerable challenge. An important part of this problem is the ability to successfully distinguish the extent to which a given gesture is determined by the neuromotor impairment and that which is determined by a compensatory mechanism. This question is particularly complicated in tasks involving manual dexterity where prehensile movements are contingent upon the task (individual digit movement, grasping, and manipulation…) and its objective (placing, two step actions…), as well as personal factors (motivation, acquired skills, and life habits…) and contextual cues related to the environment (presence of tools or assistive devices…). Presently, there remains a lack of integrative studies which differentiate processes related to structural changes associated with the neurological lesion and those related to behavioral change in response to situational constraints. In this text, we shall question the link between impairments, motor strategies and individual performance in object handling tasks. This scoping review will be based on clinical studies, and discussed in relation to more general findings about hand and upper limb function (manipulation of objects, tool use in daily life activity). We shall discuss how further quantitative studies on human manipulation in ecological contexts may provide greater insight into compensatory motor behavior in patients with a neurological impairment of dexterous upper-limb function.

Optimal multi-field functional electrical stimulation parameters for the "drinking task - reaching phase" and related upper limb kinematics repeatability in post stroke subjects

BACKGROUND

No specific guidelines for the management of functional electrical stimulation (FES) parameters in post stroke patients have been defined yet, despite its frequent use. The purpose of this study is to characterize the optimal FES parameters that assist the reaching phase of drinking task ("drinking task - reaching phase") on post stroke subjects and to analyze the related upper limb (UL) movement quality indicators repeatability.

METHODS

An observational study with a test and re-test design involving ten post stroke subjects with UL dysfunction was performed. End-point and joint kinematics of contralesional UL were assessed during the "drinking task - reaching phase" with FES through a test and retest design. FES parameters were adjusted to improve UL function according to a consensus between physiotherapists and patients' perspective.

FINDINGS

It was possible to establish reliable FES parameters that assisted the "drinking task - reaching phase". All FES parameters presented high to very high repeatability and led to moderate to very high repeatability in almost UL movement quality indicators during the "drinking task - reaching phase".

INTERPRETATION

These findings show that the main characteristics of FES parameters that improves patient perception of change are quite stable, which facilitate its implementation in clinical practice by allowing consistence between intervention sessions.

Association Between Finger-to-Nose Kinematics and Upper Extremity Motor Function in Subacute Stroke: A Principal Component Analysis

Background

Kinematic analysis facilitates interpreting the extent and mechanisms of motor restoration after stroke. This study was aimed to explore the kinematic components of finger-to-nose test obtained from principal component analysis (PCA) and the associations with upper extremity (UE) motor function in subacute stroke survivors.

Methods

Thirty-seven individuals with subacute stroke and twenty healthy adults participated in the study. Six kinematic metrics during finger-to-nose task (FNT) were utilized to perform PCA. Clinical assessments for stroke participants included the Fugl-Meyer Assessment for Upper Extremity (FMA-UE), Action Research Arm Test (ARAT), and Modified Barthel Index (MBI).

Results

Three principal components (PC) accounting for 91.3% variance were included in multivariable regression models. PC1 (48.8%) was dominated by mean velocity, peak velocity, number of movement units (NMU) and normalized integrated jerk (NIJ). PC2 (31.1%) described percentage of time to peak velocity and movement time. PC3 (11.4%) profiled percentage of time to peak velocity. The variance explained by principal component regression in FMA-UE (R² = 0.71) were higher than ARAT (R² = 0.59) and MBI (R² = 0.29) for stroke individuals.

Conclusion

Kinematic components during finger-to-nose test identified by PCA are associated with UE motor function in subacute stroke. PCA reveals the intrinsic association among kinematic metrics, which may add value to UE assessment and future intervention targeted for kinematic components for stroke individuals.

Clinical Trial Registration

Chinese Clinical Trial Registry (http://www.chictr.org.cn/) on 17 October 2019, identifier: ChiCTR1900026656.

Reaching performance scale for stroke - Test-retest reliability, measurement error, concurrent and discriminant validity

INTRODUCTION

Post-stroke upper limb motor improvement can be better quantified by describing movement patterns characterizing movement quality and use of compensations. Movement patterns can be described using both kinematic and clinical outcomes. One clinical outcome that assesses movement quality and compensations used for reaching a Close (18 points) and Far target (18 points) is the Reaching Performance Scale for Stroke (RPSS).

OBJECTIVE

To estimate the pilot test-retest reliability and validity (concurrent, discriminant) of the RPSS in individuals with chronic stroke.

DESIGN

Retrospective data analysis.

SETTING

Research laboratory.

PARTICIPANTS

Seventy-two individuals with upper limb hemiparesis ≥6 months prior to participation.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURE

RPSS Close and Far Target scores. Intraclass correlation coefficients (ICCs) helped assess pilot test-retest reliability on a subset of 14 participants. Concurrent validity was assessed for individual RPSS items with corresponding kinematic outcomes (trunk displacement, shoulder flexion, shoulder horizontal adduction, elbow extension, trajectory straightness) using Pearson correlations. We also ran multiple regression analyses with the RPSS total scores and used kinematic outcomes as the criterion standard. Logistic regression analyses estimated discriminant validity. We divided participants into two groups based on the Fugl-Meyer Assessment (FMA) scores (mild: ≥50/66; moderate-to-severe: ≤49/66).

RESULTS

Test-retest reliability was excellent for Close (ICC = 0.98, 95% confidence interval [CI] 0.94-0.99) and Far targets (ICC = 0.98, 95% CI 0.95-0.99). Individual RPSS items for both targets were mildly to moderately correlated with corresponding kinematic values. A combination of trajectory straightness, elbow extension, and trunk displacement explained the majority of the variance in RPSS scores (47%) for both targets. The RPSS scores discriminated between individuals with mild and moderate-to-severe motor impairment for both Close (ExpB = 3.33, P < .001; 95% CI 1.70-6.52) and Far targets (ExpB = 2.59, P < .001, 95% CI 1.65-4.07). Cutoff points for transition between groups were 15.5 (Close target) and 14 (Far target).

CONCLUSION

The RPSS is a valid clinical measure with excellent pilot results of test-retest reliability for assessing movement patterns and compensations used for reaching.

Compensatory Trunk Movements in Naturalistic Reaching and Manipulation Tasks in Chronic Stroke Survivors

Impairment of arm movements poststroke often results in the use of compensatory trunk movements to complete motor tasks. These compensatory movements have been mostly observed in tightly controlled conditions, with very few studies examining them in more naturalistic settings. In this study, the authors quantified the presence of compensatory movements during a set of continuous reaching and manipulation tasks performed with both the paretic and nonparetic arm (in 9 chronic stroke survivors) or the dominant arm (in 20 neurologically unimpaired control participants). Kinematic data were collected using motion capture to assess trunk and elbow movement. The authors found that trunk displacement and rotation were significantly higher when using the paretic versus nonparetic arm (P = .03). In contrast, elbow angular displacement was significantly lower in the paretic versus nonparetic arm (P = .01). The reaching tasks required significantly higher trunk compensation and elbow movement than the manipulation tasks. These results reflect increased reliance on compensatory trunk movements poststroke, even in everyday functional tasks, which may be a target for home rehabilitation programs. This study provides a novel contribution to the rehabilitation literature by examining the presence of compensatory movements in naturalistic reaching and manipulation tasks.

Optimal Multifield Functional Electrical Stimulation Parameters for the "Turn on the Light" Task and Related Upper Limb Kinematics Repeatability in Poststroke Subjects

OBJECTIVE

To characterize the optimal functional electrical stimulation (FES) parameters that assist the turn on the light task (TOTL) on poststroke participants and to analyze the related upper limb (UL) kinematics repeatability.

DESIGN

Cross-sectional study.

SETTING

Human movement research center.

PARTICIPANTS

Poststroke individuals (N=11) with history of a single unilateral stroke that resulted in a motor control dysfunction of the contralesional UL.

INTERVENTIONS

FES based on surface multifield technology applied to the contralesional wrist and finger extensors during the TOTL.

MAIN OUTCOME MEASURES

FES outcome metrics (virtual electrodes, stimulation duration, intensity) and kinematic metrics (end-point kinematics [absolute and relative duration, mean and peak velocities, relative instant of peak velocity, index of curvature, number of movement units] and joint kinematics [shoulder, elbow, wrist end position and range of movement]). Outcome measures were assessed 2 times with a 72-hour maximum time interval.

CONCLUSION

It was possible to establish reliable FES parameters that assisted the TOTL on poststroke participants. These stimulation parameters led to high to very high repeatability in terms of UL kinematics for most of the cases.

Commercial head-mounted display virtual reality for upper extremity rehabilitation in chronic stroke: a single-case design study

Background

Rehabilitation is crucial for maximizing recovery after stroke. Rehabilitation activities that are fun and rewarding by themselves can be more effective than those who are not. Gamification with virtual reality (VR) exploits this principle. This single-case design study probes the potential for using commercial off-the-shelf, room-scale head-mounted virtual reality for upper extremity rehabilitation in individuals with chronic stroke, the insights of which can inform further research.

Methods

A heterogeneous volunteer sample of seven participants living with stroke were recruited through advertisement. A single-case design was employed with a 5-week baseline (A), followed by a 10-week intervention (B) and a 6-month follow-up. Upper extremity motor function was assessed with validated kinematic analysis of drinking task. Activity capacity was assessed with Action Research Arm Test, Box and Block Test and ABILHAND questionnaire. Assessments were done weekly and at follow-up. Playing games on a VR-system with head-mounted display (HTC Vive) was used as rehabilitation intervention. Approximately 300 games were screened and 6 tested. Visual analysis and Tau-U statistics were used to interpret the results.

Results

Visual analysis of trend, level shift and overlap as well as Tau-U statistics indicated improvement of Action Research Arm Test in six participants. Four of these had at least a moderate Tau-U score (0.50–0.92), in at least half of the assessed outcomes. These four participants trained a total of 361 to 935 min. Two out of four participants who were able to perform the drinking task, had the highest training dose (> 900 min) and showed also improvements in kinematics. The predominant game played was Beat Saber. No serious adverse effects related to the study were observed, one participant interrupted the intervention phase due to a fall at home.

Conclusions

This first study of combining commercial games, a commercial head-mounted VR, and commercial haptic hand controls, showed promising results for upper extremity rehabilitation in individuals with chronic stroke. By being affordable yet having high production values, as well as being an easily accessible off-the-shelf product, this variant of VR technology might facilitate widespread adaption. Insights garnered in this study can facilitate the execution of future studies.

Trial registration The study was registered at researchweb.org (project number 262331, registered 2019-01-30, https://www.researchweb.org/is/vgr/project/262331) prior to participant enrolment.

Technology-aided assessment of functionally relevant sensorimotor impairments in arm and hand of post-stroke individuals

BACKGROUND

Assessing arm and hand sensorimotor impairments that are functionally relevant is essential to optimize the impact of neurorehabilitation interventions. Technology-aided assessments should provide a sensitive and objective characterization of upper limb impairments, but often provide arm weight support and neglect the importance of the hand, thereby questioning their functional relevance. The Virtual Peg Insertion Test (VPIT) addresses these limitations by quantifying arm and hand movements as well as grip forces during a goal-directed manipulation task requiring active lifting of the upper limb against gravity. The aim of this work was to evaluate the ability of the VPIT metrics to characterize arm and hand sensorimotor impairments that are relevant for performing functional tasks.

METHODS

Arm and hand sensorimotor impairments were systematically characterized in 30 chronic stroke patients using conventional clinical scales and the VPIT. For the latter, ten previously established kinematic and kinetic core metrics were extracted. The validity and robustness of these metrics was investigated by analyzing their clinimetric properties (test-retest reliability, measurement error, learning effects, concurrent validity).

RESULTS

Twenty-three of the participants, the ones with mild to moderate sensorimotor impairments and without strong cognitive deficits, were able to successfully complete the VPIT protocol (duration 16.6 min). The VPIT metrics detected impairments in arm and hand in 90.0% of the participants, and were sensitive to increased muscle tone and pathological joint coupling. Most importantly, significant moderate to high correlations between conventional scales of activity limitations and the VPIT metrics were found, thereby indicating their functional relevance when grasping and transporting objects, and when performing dexterous finger manipulations. Lastly, the robustness of three out of the ten VPIT core metrics in post-stroke individuals was confirmed.

CONCLUSIONS

This work provides evidence that technology-aided assessments requiring goal-directed manipulations without arm weight support can provide an objective, robust, and clinically feasible way to assess functionally relevant sensorimotor impairments in arm and hand in chronic post-stroke individuals with mild to moderate deficits. This allows for a better identification of impairments with high functional relevance and can contribute to optimizing the functional benefits of neurorehabilitation interventions.

Can kinematic parameters of 3D reach-to-target movements be used as a proxy for clinical outcome measures in chronic stroke rehabilitation? An exploratory study

BACKGROUND

Despite numerous trials investigating robot-assisted therapy (RT) effects on upper-extremity (UE) function after stroke, few have explored the relationship between three-dimensional (3D) reach-to-target kinematics and clinical outcomes. The objectives of this study were to 1) investigate the correlation between kinematic parameters of 3D reach-to-target movements and UE clinical outcome measures, and 2) examine the degree to which differences in kinematic parameters across individuals can account for differences in clinical outcomes in response to RT.

METHODS

Ten chronic stroke survivors participated in a pilot RT intervention (eighteen 1-h sessions) integrating cognitive skills training and a home-action program. Clinical outcome measures and kinematic parameters of 3D reach-to-target movements were collected pre- and post-intervention. The correlation between clinical outcomes and kinematic parameters was investigated both cross-sectionally and longitudinally (i.e., changes in response to the intervention). Changes in clinical outcomes and kinematic parameters were tested for significance in both group and subject-by-subject analyses. Potential associations between individual differences in kinematic parameters and differences in clinical outcomes were examined.

RESULTS

Moderate-to-strong correlation was found between clinical measures and specific kinematic parameters when examined cross-sectionally. Weaker correlation coefficients were found longitudinally. Group analyses revealed significant changes in clinical outcome measures in response to the intervention; no significant group changes were observed in kinematic parameters. Subject-by-subject analyses revealed changes with moderate-to-large effect size in the kinematics of 3D reach-to-target movements pre- vs. post-intervention. Changes in clinical outcomes and kinematic parameters varied widely across participants.

CONCLUSIONS

Large variability was observed across subjects in response to the intervention. The correlation between changes in kinematic parameters and clinical outcomes in response to the intervention was variable and not strong across parameters, suggesting no consistent change in UE motor strategies across participants. These results highlight the need to investigate the response to interventions at the individual level. This would enable the identification of clusters of individuals with common patterns of change in response to an intervention, providing an opportunity to use cluster-specific kinematic parameters as a proxy of clinical outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02747433 . Registered on April 21st, 2016.

A data-driven framework for selecting and validating digital health metrics: use-case in neurological sensorimotor impairments

Digital health metrics promise to advance the understanding of impaired body functions, for example in neurological disorders. However, their clinical integration is challenged by an insufficient validation of the many existing and often abstract metrics. Here, we propose a data-driven framework to select and validate a clinically relevant core set of digital health metrics extracted from a technology-aided assessment. As an exemplary use-case, the framework is applied to the Virtual Peg Insertion Test (VPIT), a technology-aided assessment of upper limb sensorimotor impairments. The framework builds on a use-case-specific pathophysiological motivation of metrics, models demographic confounds, and evaluates the most important clinimetric properties (discriminant validity, structural validity, reliability, measurement error, learning effects). Applied to 77 metrics of the VPIT collected from 120 neurologically intact and 89 affected individuals, the framework allowed selecting 10 clinically relevant core metrics. These assessed the severity of multiple sensorimotor impairments in a valid, reliable, and informative manner. These metrics provided added clinical value by detecting impairments in neurological subjects that did not show any deficits according to conventional scales, and by covering sensorimotor impairments of the arm and hand with a single assessment. The proposed framework provides a transparent, step-by-step selection procedure based on clinically relevant evidence. This creates an interesting alternative to established selection algorithms that optimize mathematical loss functions and are not always intuitive to retrace. This could help addressing the insufficient clinical integration of digital health metrics. For the VPIT, it allowed establishing validated core metrics, paving the way for their integration into neurorehabilitation trials.

Comparison of upper limb kinematics in two activities of daily living with different handling requirements

INTRODUCTION

Recently, kinematic analysis of the drinking task (DRINK) has been recommended to assess the quality of upper limb (UL) movement after stroke, but the accomplishment of this task may become difficult for poststroke patients with hand impairment. Therefore, it is necessary to study ADLs that involve a simpler interaction with a daily life target, such as the turning on a light task (LIGHT). As the knowledge of movement performed by healthy adults becomes essential to assess the quality of movement of poststroke patients, the main goal of this article was to compare the kinematic strategies used by healthy adults in LIGHT with those that are used in DRINK.

METHODS

63 adults, aged 30 to 69 years old, drank water and turned on a light, using both ULs separately, while seated. The movements of both tasks were captured by a 3D motion capture system. End-point and joint kinematics of reaching and returning phases were analysed. A multifactorial analysis of variance with repeated measures was applied to the kinematic metrics, using age, sex, body mass index and dominance as main factors.

RESULTS

Mean and peak velocities, index of curvature, shoulder flexion and elbow extension were lower in LIGHT, which suggests that the real hand trajectory was smaller in this task. In LIGHT, reaching was less smooth and returning was smoother than DRINK. The instant of peak velocity was similar in both tasks. There was a minimal anterior trunk displacement in LIGHT, and a greater anterior trunk displacement in DRINK. Age and sex were the main factors which exerted effect on some of the kinematics, especially in LIGHT.

CONCLUSION

The different target formats and hand contact in DRINK and LIGHT seem to be responsible for differences in velocity profile, efficiency, smoothness, joint angles and trunk displacement. Results suggest that the real hand trajectory was smaller in LIGHT and that interaction with the switch seems to be less demanding than with the glass. Accordingly, LIGHT could be a good option for the assessment of poststroke patients without grasping ability. Age and sex seem to be the main factors to be considered in future studies for a better match between healthy and poststroke adults.

Virtual reality interventions to enhance upper limb motor improvement after a stroke: commonly used types of platform and outcomes

Introduction: Virtual Reality (VR) based platforms are useful in enhancing post-stroke sub-optimal upper limb (UL) motor improvement. A variety of options are available from expensive highly customizable platforms to low cost turnkey solutions. Clinical outcomes primarily help assess the effects of VR-based platforms. These outcomes mainly quantify how much improvement has occurred. Very few outcomes characterize the type (i.e. how) of recovery. We categorized the types of VR-based platforms and outcome measures commonly used for post-stroke UL motor improvement.Methods: We reviewed the published literature in English from 2000-2019. Different types of VR-based platforms were grouped into those available commercially and those developed by the various research groups. We initially classified outcomes from the retrieved studies under the appropriate International Classification of Functioning categories. Then, we divided the outcomes as those quantifying the type or extent of improvement.Results: We found a total of 125 studies. Majority of the studies used commercially available platforms. A total of 42 different outcome measures were used. Seventeen different outcomes were used to assess body structure and functions as well as in activity limitations. Eight outcomes assessed the effects of contextual factors and participation restrictions. The Fugl Meyer Assessment, Wolf Motor Function Test and Stroke Impact Scale were most often used across the three categories. Of the 125 studies, 52 used outcomes characterizing the type of recovery. Although a smaller proportion, 24 studies included movement patterns outcomes.Conclusion: A standardized set of outcomes can promote better comparisons between studies using different VR-based platforms for post-stroke UL motor improvement.Implications for RehabilitationA wide variety of commercially available systems are present from expensive customizable systems to low-cost turnkey systems.The Fugl-Meyer Assessment and Wolf Motor Function Test along with the Stroke Impact Scale-Social Participation subscale were used most often across all studies as assessments of body structure and function, activity limitations and participation restriction.It is essential to include movement pattern outcomes addressing whether recovery of compensation occurs with the use of VR-based platforms.

An interactive motion-tracking system for home-based assessing and training reach-to-target tasks in stroke survivors-a preliminary study

Quantitative evaluation and training of the reach-to-target ability in stroke patients are needed for postdischarge rehabilitation, which can be achieved using a motion-tracking system. However, most of these systems are either costly, involve sophisticated parameter interpretation, or are not designed for rehabilitation. We developed an interactive reach-to-target assessment and training system (IRTATS) based on a camera and three marker straps to detect tracking signals. IRTATS supports audiovisual feedback, personal goal setting, and use in a small clinic or home without the internet. This study aims to evaluate the reliability, validity of IRTATS, and its measurement accuracy of the range of motion (ROM). Ninety-nine stroke patients and 20 healthy adults were recruited for the study. Kinematic variables and active joint ROM (AROM) were assessed using IRTATS. The AROM was measured by a universal goniometer, and scores from multiple clinical scales concerning motor and activity capability were calculated. Although the AROMs measured by IRTATS and the goniometer did not agree, IRTATS has clinically acceptable reliability and validity. Three variables in IRTATS could discriminate the motor performance of patients and healthy subjects. IRTATS may provide a new supplement to conventional physiotherapy in the assessment of the reach-to-target ability in stroke patients. Graphical abstract System configuration • The system is based on an infrared camera and the adjustable marker straps as a sensor module. • It is portable and compact, and has clinically acceptable reliability and validity. • It supports audiovisual feedback, personal goal setting, and use in regions without the internet. • It can be used as an adjunct to conventional physiotherapy in the assessment of the reach-to-target ability.

Relationship between self-reported and objectively measured manual ability varies during the first year post-stroke

Self-reported outcomes provide unique insights about an individual’s perceived manual ability after stroke. This study aimed at determining how the relationship between objective kinematic variables obtained from the target-to-target pointing task and self-reported manual ability varies during the first year in individuals after stroke. Sixty-six individuals from the Stroke Arm Longitudinal study at the University of Gothenburg (SALGOT) cohort were assessed using ABILHAND questionnaire and kinematic analysis at five timepoints between the 10^th day and 12^th month after stroke. Kinematic analysis was performed using a target-to-target pointing task in a virtual environment. Spearman’s correlation was used to determine the extent of correlation between ABILHAND logits and kinematic variables. The correlations varied with time within the first year after stroke. The correlations were low or very low early after stroke and became moderate to high after 6 months for objective measures of movement time and smoothness, but remained low to moderate for mean velocity and low for peak velocity. Due to this discrepancy between self-perceived and objective assessments of arm function, a combination of self-reported and objective assessments of upper limb should be used as outcome measures, especially in the acute and subacute stages after stroke.

Fugl-Meyer Assessment Scores Are Related With Kinematic Measures in People with Chronic Hemiparesis after Stroke

BACKGROUND

Stroke often results in motor impairment and limited functional capacity. This study aimed to verify the relationship between widely used clinical scales and instrumented measurements to evaluate poststroke individuals with mild, moderate, and severe motor impairment.

METHODS

This cross-sectional study included 34 participants with chronic hemiparesis after stroke. Fugl-Meyer Assessment and Modified Ashworth Scale were used to quantify upper and lower limb motor impairment and the resistance to passive movement (i.e., spasticity), respectively. Upper limb Motor performance (movement time and velocities) and movement quality (range of motion, smoothness and trunk displacement) were analyzed during a reaching forward task using an optoelectronic system (instrumented measurement). Lower limb motor performance (gait and functional mobility parameters) was assessed by using an inertial measurement unit system.

FINDINGS

Fugl-Meyer Assessment correlated with motor performance (upper and lower limbs) and with movement quality (upper limb). Modified Ashworth scale correlated with movement quality (upper limb). Cutoff values of 9.0 cm in trunk anterior displacement and .57 m/s in gait velocity were estimated to differentiate participants with mild/moderate and severe compromise according to the Fugl-Meyer Assessment.

CONCLUSIONS

These results suggest that the Fugl-Meyer Assessment can be used to infer about motor performance and movement quality in chronic poststroke individuals with different levels of impairment.

Dynamics of post-stroke hand paresis kinematic pattern during rehabilitation

According to the literature data, only 5–20% of post-stroke patients are able to restore the hand motor function completely. Correct goal setting and individual approach to the patient's functional recovery are important. Our study aimed to develop an algorithm of impaired hand motor functioning assessment for post-stroke patients and to determine the principles of the rehabilitation tactics choosing based on the biomechanical analysis. Twenty five patients with hemispheric stroke and 10 healthy volunteers participated in the study. Formal clinical observation scales (Fugl-Meyer Assessment, Ashworth Scale, ARAT) and video motion analysis were used for evaluation of the hand motor function. Patients were divided into 2 groups according to the hand paresis severity (mild/moderate and pronounced/severe). Rehabilitation was carried out in both groups, including mechanotherapy, massage and physical therapy. It was revealed that in the 1st group of patients the motor function recovery in the paretic hand was due to movement performance recovery: biomechanical parameters restoration directly correlated with a decrease in the paresis degree according to the Fugl-Meyer Assessment Scale (r = 0.94; p = 0.01). In the 2nd group of patients, the motor function recovery in the paretic hand was due to motor deficit compensation: according to biomechanical analysis, the pathological motor synergies inversely correlated with a decrease in the paresis degree (r = –0.9; p = 0.03). As a result of the study, an algorithm for selecting the patient management tactics based on the baseline clinical indicators was developed.

End-point kinematics using virtual reality explaining upper limb impairment and activity capacity in stroke

BACKGROUND

For evaluation of upper limb impairment and activity capacity, Fugl-Meyer Assessment of Upper Extremity (FMA-UE) and Action Research Arm Test (ARAT) are recommended to be included in stroke trials. To improve the understanding of mechanisms of motor recovery, and differentiate between restitution and compensation, kinematic analysis is also recommended for assessment of upper limb function after stroke.

AIM

To determine the extent to which end-point kinematic variables obtained from the target-to-target pointing task were associated with upper limb impairment or activity limitation as assessed by traditional clinical scales in individuals with stroke.

METHODS

Sixty-four individuals, from acute stage up to one year after stroke, were included from the Stroke Arm Longitudinal study at the University of Gothenburg (SALGOT) cohort. They performed a target-to-target pointing task in a virtual environment using a haptic stylus which also captured the kinematic parameters. Multiple linear regression was done to determine the amount of variance explained by kinematic variables on FMA-UE and ARAT scores after controlling for confounding variables.

RESULTS

Mean velocity and number of velocity peaks explained 11 and 9% of the FMA-UE score uniquely and 16% when taken together. Movement time and number of velocity peaks explained 13 and 10% of the ARAT score respectively.

CONCLUSION

The kinematic variables of movement time, velocity and smoothness explain only a part of the variance captured by using clinical observational scales, reinforcing the importance of multi-level assessment using both kinematic analysis and clinical scales in upper limb evaluation after stroke.

TRIAL REGISTRATION

The trial was registered with register number NCT01115348 at clinicaltrials.gov , on May 4, 2010. URL: https://clinicaltrials.gov/ct2/show/NCT01115348 .

Relationship Between Clinical Measures of Upper Limb Movement Quality and Activity Poststroke

Background. Understanding the relationship between movement quality (impairment) and performance (activity) in poststroke patients is important for rehabilitation intervention studies. This has led to an interest in kinematic characterization of upper limb motor impairment. Since instrumented motion analysis is not readily clinically available, observational kinematics may be a viable alternative. Objective. To determine if upper limb movement quality during a reach-to-grasp task identified by observation could be used to describe the relationship between motor impairments and the time to perform functional tasks. Methods. Cross-sectional, secondary analysis of baseline data from 141 participants with stroke, age 18 to 85 years, who participated in a multicenter randomized controlled trial. Clinical assessment of movement quality using the Reaching Performance Scale for Stroke (RPSS-Close and Far targets) and of performance (activity) from the Wolf Motor Function Test (WMFT-7 items) was assessed. The degree to which RPSS component scores explained scores on WMFT items was determined by multivariable regression. Results. Clinically significant decreases (>2 seconds) in performance time for some of the more complex WMFT tasks involving prehension were predicted from RPSS-Close and Far target components. Trunk compensatory movements did not predict either increases or decreases in performance time for the WMFT tasks evaluated. Overall, the strength of the regression models was low. Conclusions. In lieu of kinematic analysis, observational clinical movement analysis may be a valid and accessible method to determine relationships between motor impairment, compensations and upper limb function in poststroke patients. Specific relationships are unlikely to generalize to all tasks due to kinematic redundancy and task specificity.

Methodological considerations for kinematic analysis of upper limbs in healthy and poststroke adults Part II: a systematic review of motion capture systems and kinematic metrics

Background and purpose: To review the methods used to analyze the kinematics of upper limbs (ULs) of healthy and poststroke adults, namely the motion capture systems and kinematic metrics. Summary of review: A database of articles published in the last decade was compiled using the following search terms combinations: ("upper extremity" OR "upper limb" OR arm) AND (kinematic OR motion OR movement) AND (analysis OR assessment OR measurement). The articles included in this review: (1) had the purpose to analyze objectively three-dimension kinematics of ULs, (2) studied functional movements or activities of daily living involving ULs, and (3) studied healthy and/or poststroke adults. Fourteen articles were included (four studied a healthy sample, three analyzed poststroke patients, and seven examined both poststroke and healthy participants). Conclusion: Most articles used optoelectronic systems with markers; however, the presentation of laboratory and task-specific errors is missing. Markerless systems, used in some studies, seem to be promising alternatives for implementation of kinematic analysis in hospitals and clinics, but the literature proving their validity is scarce. Most articles analyzed "joint kinematics" and "end-point kinematics," mainly related with reaching. The different stroke locations of the samples were not considered in their analysis and only three articles described their psychometric properties. Implication of key findings: Future research should validate portable motion capture systems, document their specific error at the acquisition place and for the studied task, include grasping and manipulation analysis, and describe psychometric properties.

Upper-limb movement smoothness after stroke and its relationship with measures of body function/structure and activity - A cross-sectional study

INTRODUCTION

After a stroke, upper limb (UL) motor impairments interfere with functional activities and quality of life. Even though a range of assessment tools has been developed to assess UL, few studies explore the interfaces between different levels of functioning after stroke.

OBJECTIVES

(a) verify the correlation between movement smoothness and other measures of body function/structure [UL - Fugl-Meyer Assessment (FMA), and handgrip strength]; (b) verify which body function/structure [UL-FMA and/or handgrip strength] could predict UL movement smoothness; and (c) verify if movement smoothness could predict levels of activity, as assessed by the Box and Block Test (BBT).

MATERIALS AND METHODS

Cross-sectional study. Thirty-four individuals with chronic hemiparesis after stroke were enrolled. Measurements of body function/structure included FMA, handgrip strength and kinematic measure of movement smoothness. Levels of activity were measured using the Box and Block Test (BBT).

RESULTS

Movement smoothness showed strong correlation with FMA (r = 0.70, p < .001) and moderate correlation with handgrip strength (r = 0.63, p < .001). FMA explained 46.4% of the variation in movement smoothness. Movement smoothness was moderately correlated with BBT (r = -0.560, p < .005) and predicted 31% of the variation in BBT.

CONCLUSION

We recommend the use of UL-FMA to predict movement smoothness in chronic post-stroke subjects. This study also showed that movement smoothness influences the level of activity. Then, movement smoothness may be emphasized during stroke rehabilitation to enhance the UL level of activity in chronic post-stroke subjects.

A modified standardized nine hole peg test for valid and reliable kinematic assessment of dexterity post-stroke

BACKGROUND

Impairments in dexterity after stroke are commonly assessed by the Nine Hole Peg Test (NHPT), where the only outcome variable is the time taken to complete the test. We aimed to kinematically quantify and to compare the motor performance of the NHPT in persons post-stroke and controls (discriminant validity), to compare kinematics to clinical assessments of upper extremity function (convergent validity), and to establish the within-session reliability.

METHODS

The NHPT was modified and standardized (S-NHPT) by 1) replacing the original peg container with an additional identical nine hole pegboard, 2) adding a specific order of which peg to pick, and 3) specifying to insert the peg taken from the original pegboard into the corresponding hole of the target pegboard. Eight optical cameras registered upper body kinematics of 30 persons post-stroke and 41 controls during the S-NHPT. Four sequential phases of the task were identified and analyzed for kinematic group differences. Clinical assessments were performed.

RESULTS

The stroke group performed the S-NHPT slower (total movement time; mean diff 9.8 s, SE diff 1.4), less smoothly (number of movement units; mean diff 0.4, SE diff 0.1) and less efficiently (path ratio; mean diff 0.05, SE diff 0.02), and used increased scapular/trunk movements (acromion displacement; mean diff 15.7 mm, SE diff 3.5) than controls (P < 0.000, r ≥ 0.32), indicating discriminant validity. The stroke group also spent a significantly longer time grasping and releasing pegs relative to the transfer phases of the task compared to controls. Within the stroke group, kinematics correlated with time to complete the S-NHPT and the Fugl-Meyer Assessment (rs 0.38-0.70), suggesting convergent validity. Within-session reliability for the S-NHPT was generally high to very high for both groups (ICCs 0.71-0.94).

CONCLUSIONS

The S-NHPT shows adequate discriminant validity, convergent validity and within-session reliability. Standardization of the test facilitates kinematic analysis of movement performance, which in turn enables identification of differences in movement control between persons post-stroke and controls that may otherwise not be captured through the traditional time-based NHPT. Future research should ascertain further psychometric properties, e.g. sensitivity, of the S-NHPT.

Methodological considerations for kinematic analysis of upper limbs in healthy and poststroke adults. Part I: A systematic review of sampling and motor tasks

BACKGROUND AND PURPOSE

The purpose of this study was to review the methods used to analyze the kinematics of upper limbs (ULs) of healthy and poststroke adults, namely specificities of sampling and motor tasks.

SUMMARY OF REVIEW

A database of articles published in the last decade was compiled using the following search terms combinations: ("upper extremity" OR "upper limb" OR arm) AND (kinematics OR motion OR movement) AND (analysis OR assessment OR measurement). The articles included in this review (1) had the purpose to analyze objectively a three-dimension kinematics of ULs, (2) studied functional movements or activities of daily living (ADL) involving uppers limbs, and (3) studied healthy and/or poststroke adults. Fourteen articles were included (four studied a healthy sample, three analyzed poststroke patients, and seven examined both poststroke and healthy participants).

CONCLUSION

Most of the recommended demographic and stroke information, such as some preexisting conditions to stroke, initial stroke severity, and stroke location, were not collected by all or most of the articles. Time poststroke onset was presented in all articles but showed great variability. Few articles identified anthropometric characteristics and adjusted task environment to them. Most of the samples were composed mainly by males and had a low mean age, which does not represent poststroke population. Most articles analyzed "functional movements", namely simulations of ADL. Implication of key findings: Future research should identify the recommended information to allow an adequate stratification. Acute phase after stroke, real ADL with different complexities, and ipsilesional UL should be studied.

Smoothness Metrics in Complex Movement Tasks

Smoothness is a main characteristic of goal-directed human movements. The suitability of approaches quantifying movement smoothness is dependent on the analyzed signal's structure. Recently, activities of daily living (ADL) received strong interest in research on aging and neurorehabilitation. Such tasks have complex signal structures and kinematic parameters need to be adapted. In the present study we examined four different approaches to quantify movement smoothness in ADL. We tested the appropriateness of these approaches, namely the number of velocity peaks per meter (NoP), the spectral arc length (SAL), the speed metric (SM) and the log dimensionless jerk (LDJ), by comparing movement signals from eight healthy elderly (67.1a ± 7.1a) with eight healthy young (26.9a ± 2.1a) participants performing an activity of daily living (making a cup of tea). All approaches were able to identify group differences in smoothness (Cohen's d NoP = 2.53, SAL = 1.95, SM = 1.69, LDJ = 4.19), three revealed high to very high sensitivity (z-scores: NoP = 1.96 ± 0.55, SAL = 1.60 ± 0.64, SM = 3.41 ± 3.03, LDJ = 5.28 ± 1.52), three showed low within-group variance (NoP = 0.72, SAL = 0.60, SM = 0.11, LDJ = 0.71), two showed strong correlations between the first and the second half of the task execution (intra-trial R2s: NoP = 0.22 n.s., SAL = 0.33, SM = 0.36, LDJ = 0.91), and one was independent of other kinematic parameters (SM), while three showed strong models of multiple linear regression (R2s: NoP = 0.61, SAL = 0.48, LDJ = 0.70). Based on our results we make suggestion toward use examined smoothness measures. In total the log dimensionless jerk proved to be the most appropriate in ADL, as long as trial durations are controlled.

Translational effects of robot-mediated therapy in subacute stroke patients: an experimental evaluation of upper limb motor recovery

Robot-mediated therapies enhance the recovery of post-stroke patients with motor deficits. Repetitive and repeatable exercises are essential for rehabilitation following brain damage or other disorders that impact the central nervous system, as plasticity permits to reorganize its neural structure, fostering motor relearning. Despite the fact that so many studies claim the validity of robot-mediated therapy in post-stroke patient rehabilitation, it is still difficult to assess to what extent its adoption improves the efficacy of traditional therapy in daily life, and also because most of the studies involved planar robots. In this paper, we report the effects of a 20-session-rehabilitation project involving the Armeo Power robot, an assistive exoskeleton to perform 3D upper limb movements, in addition to conventional rehabilitation therapy, on 10 subacute stroke survivors. Patients were evaluated through clinical scales and a kinematic assessment of the upper limbs, both pre- and post-treatment. A set of indices based on the patients' 3D kinematic data, gathered from an optoelectronic system, was calculated. Statistical analysis showed a remarkable difference in most parameters between pre- and post-treatment. Significant correlations between the kinematic parameters and clinical scales were found. Our findings suggest that 3D robot-mediated rehabilitation, in addition to conventional therapy, could represent an effective means for the recovery of upper limb disability. Kinematic assessment may represent a valid tool for objectively evaluating the efficacy of the rehabilitation treatment.

Design and Study of a Smart Cup for Monitoring the Arm and Hand Activity of Stroke Patients

This paper presents a new platform to monitor the arm and hand activity of stroke patients during rehabilitation exercises in the hospital and at home during their daily living activities. The platform provides relevant data to the therapist in order to assess the patients physical state and adapt the rehabilitation program if necessary. The platform consists of a self-contained smart cup that can be used to perform exercises that are similar to everyday tasks such as drinking. The first smart cup prototype, the design of which was based on interviews regarding the needs of therapists, contains various sensors that collect information about its orientation, the liquid level, its position compared to a reference target and tremors. The prototype also includes audio and visual displays that provide feedback to patients about their movements. Two studies were carried out in conjunction with healthcare professionals and patients. The first study focused on collecting feedback from healthcare professionals to assess the functionalities of the cup and to improve the prototype. Based on this paper, we designed an improved prototype and created a visualization tool for therapists. Finally, we carried out a preliminary study involving nine patients who had experienced an ischemic or hemorrhagic stroke in the previous 24 months. This preliminary study focused on assessing the usability and acceptability of the cup to the patients. The results showed that the cup was very well accepted by eight of the nine patients in monitoring their activity within a rehabilitation center or at home. Moreover, these eight patients had almost no concerns about the design of the cup and its usability.

Strong relations of elbow excursion and grip strength with post-stroke arm function and activities: Should we aim for this in technology-supported training?

Objective

To investigate the relationships between an extensive set of objective movement execution kinematics of the upper extremity and clinical outcome measures in chronic stroke patients: at baseline and after technology-supported training at home.

Methods

Twenty mildly to severely affected chronic stroke patients participated in the baseline evaluation, 15 were re-evaluated after six weeks of intensive technology-supported or conventional arm/hand training at home. Grip strength, 3D motion analysis of a reach and grasp task, and clinical scales (Fugl-Meyer assessment (FM), Action Research Arm Test (ARAT) and Motor Activity Log (MAL)) were assessed pre- and post-training.

Results

Most movement execution parameters showed moderate-to-strong relationships with FM and ARAT, and to a smaller degree with MAL. Elbow excursion explained the largest amount of variance in FM and ARAT, together with grip strength. The only strong association after training was found between changes in ARAT and improvements in hand opening (conventional) or grip strength (technology-supported).

Conclusions

Elbow excursion and grip strength showed strongest association with post-stroke arm function and activities. Improved functional ability after training at home was associated with increased hand function. Addressing both reaching and hand function are indicated as valuable targets for (technological) treatment applications to stimulate functional improvements after stroke.

Recovery of kinematic arm function in well-performing people with subacute stroke: a longitudinal cohort study

BACKGROUND

Most motor function improvements in people who have experienced strokes occur within the first 3 months. However, individuals showing complete or nearly complete arm function recovery, as assessed using clinical scales, still show certain movement kinematic deficits at 3 months, post-stroke. This study evaluated the changes in upper extremity kinematics, in individuals demonstrating minor clinical motor impairments, 3-12 months post-stroke, and also examined the association between kinematics and the subjects's self-perceived hand abilities during the chronic stage, 12 months post-stroke.

METHODS

Forty-two subjects recovering from strokes and having Fugl-Meyer upper extremity motor assessment scores ≥60 were included from the Stroke Arm Longitudinal Study at the University of Gothenburg (SALGOT). Kinematic analyses of a drinking task, performed 3, 6, and 12 months post-stroke, were compared with kinematic analyses performed in 35 healthy controls. The Stroke Impact Scale-Hand domain was evaluated at the 12-month follow-up.

RESULTS

There were no significant changes in kinematic performance between 3 and 12 months, post-stroke. The patients recovering from stroke showed lower peak elbow extension velocities, and increased shoulder abduction and trunk displacement during drinking than did healthy controls, at all time points. At 12 months, post-stroke, better self-perceived arm functions correlated with improved trunk displacements, movement times, movement units, and time to peak velocity percentages.

CONCLUSION

Kinematic movement deficits, observed at 3 months post-stroke, remained unchanged at 12 months. Movement kinematics were associated with the patient's self-perceived ability to use their more affected hand.

TRIAL REGISTRATION

ClinicalTrials: NCT01115348 .

Kinematic Analysis Using 3D Motion Capture of Drinking Task in People With and Without Upper-extremity Impairments

Kinematic analysis is a powerful method for objective assessment of upper extremity movements in a three-dimensional (3D) space. Three-dimensional motion capture with an optoelectronic camera system is considered as golden standard for kinematic movement analysis and is increasingly used as outcome measure to evaluate the movement performance and quality after an injury or disease involving upper extremity movements. This article describes a standardized protocol for kinematic analysis of drinking task applied in individuals with upper extremity impairments after stroke. The drinking task incorporates reaching, grasping and lifting a cup from a table to take a drink, placing the cup back, and moving the hand back to the edge of the table. The sitting position is standardized to the individual's body size and the task is performed in a comfortable self-paced speed and compensatory movements are not constrained. The intention is to keep the task natural and close to a real-life situation to improve the ecological validity of the protocol. A 5-camera motion capture system is used to gather 3D coordinate positions from 9 retroreflective markers positioned on anatomical landmarks of the arm, trunk, and face. A simple single marker placement is used to ensure the feasibility of the protocol in clinical settings. Custom-made Matlab software provides automated and fast analyses of movement data. Temporal kinematics of movement time, velocity, peak velocity, time of peak velocity, and smoothness (number of movement units) along with spatial angular kinematics of shoulder and elbow joint as well as trunk movements are calculated. The drinking task is a valid assessment for individuals with moderate and mild upper extremity impairment. The construct, discriminative and concurrent validity along with responsiveness (sensitivity to change) of the kinematic variables obtained from the drinking task have been established.

Step by Step: Kinematics of the Reciprocal Trail Making Task Predict Slowness of Activities of Daily Living Performance in Alzheimer's Disease

Dementia impairs the ability to perform everyday activities. Reduced motor capacity and executive functions as well as loss of memory function and forms of apraxia and action disorganization syndrome can be reasons for such impairments. In this study, an analysis of the hand trajectories during the sequential movements in an adapted version of the trail making task, the reciprocal trail making task (RTMT), was used to predict performance in activities of daily living (ADL) of patients suffering from mild cognitive impairment and dementia. 1 patient with dementia of the Alzheimer’s type and 15 healthy, age-matched adults were tested in the standardized ADL of tea making and document filing. The characteristics of the kinematic performance in the RTMT were assessed, and models of multiple linear regression were computed to predict the durations of the ADL. Patients showed increased trial durations (TDs) in the ADL (Cohen’s d: tea making 1.64, document filing 1.25). Parameters and explained variability differed across patients and control as well as between different activities. The models for the patient sample were stronger and particularly high for the document filing task for which kinematics explained 71% of the variance (Radjusted2: tea making 0.62, document filing 0.71; both tasks combined patients 0.55, controls 0.25). The most relevant factors for the models were the TD and a parameter characterizing movement fluency and variability (“movement harmonicity”) in the RTMT. The models of multiple linear regression suggested that the patients’ activity of daily living performance was limited by cognitive demands, namely, identifying the varying targets during sequencing and the healthy controls’ performance by their motor capacity. Such models could be used to estimate the severity of ADL impairments in patients.

Effects of Wrist Weights on Kinematic and Myographic Movement Characteristics During a Reaching Task in Individuals With Parkinson Disease

OBJECTIVE

To investigate the kinematic and myographic effects of weighted wrist cuffs on individuals with Parkinson disease (PD) during a reaching task.

DESIGN

Cross-sectional study.

SETTING

Biomechanics research laboratory.

PARTICIPANTS

Individuals (N=39) with PD (n=19) and healthy age-matched control subjects (n=20).

INTERVENTIONS

Participants were instructed to reach and grasp a can at a distance of 80% of their arm length without a wrist cuff, while wearing separate 0.5- and 1.0-kg wrist cuffs, and subsequently without a wrist cuff.

MAIN OUTCOME MEASURES

Movement time, kinematic, and electromyographic data were recorded during all reach and grasp movements. Four end point coordinate strategy variables, 3 joint recruitment variables, and 2 co-contraction indices were derived from the raw data for analysis.

RESULTS

Significant interaction effects were found in the trunk and index finger movement time as the weight of the cuff increased from 0.5 to 1.0kg. The group of individuals with PD showed decreased movement times in both instances, whereas the control group showed increased movement times as the weight of the wrist cuff increased from baseline to 0.5 and 1.0kg. No group difference was observed in the co-contraction index of the upper arm and forearm.

CONCLUSIONS

Adoption of weighted wrist cuffs in the clinic should be cautiously undertaken because compensatory movements may be induced in the trunk of individuals with PD.

A Short and Distinct Time Window for Recovery of Arm Motor Control Early After Stroke Revealed With a Global Measure of Trajectory Kinematics

BACKGROUND

Studies demonstrate that most arm motor recovery occurs within three months after stroke, when measured with standard clinical scales. Improvements on these measures, however, reflect a combination of recovery in motor control, increases in strength, and acquisition of compensatory strategies.

OBJECTIVE

To isolate and characterize the time course of recovery of arm motor control over the first year poststroke.

METHODS

Longitudinal study of 18 participants with acute ischemic stroke. Motor control was evaluated using a global kinematic measure derived from a 2-dimensional reaching task designed to minimize the need for antigravity strength and prevent compensation. Arm impairment was evaluated with the Fugl-Meyer Assessment of the upper extremity (FMA-UE), activity limitation with the Action Research Arm Test (ARAT), and strength with biceps dynamometry. Assessments were conducted at: 1.5, 5, 14, 27, and 54 weeks poststroke.

RESULTS

Motor control in the paretic arm improved up to week 5, with no further improvement beyond this time point. In contrast, improvements in the FMA-UE, ARAT, and biceps dynamometry continued beyond 5 weeks, with a similar magnitude of improvement between weeks 5 and 54 as the one observed between weeks 1.5 and 5.

CONCLUSIONS

Recovery after stroke plateaued much earlier for arm motor control, isolated with a global kinematic measure, compared to motor function assessed with clinical scales. This dissociation between the time courses of kinematic and clinical measures of recovery may be due to the contribution of strength improvement to the latter. Novel interventions, focused on the first month poststroke, will be required to exploit the narrower window of spontaneous recovery for motor control.

Effects of Stroke on Ipsilesional End-Effector Kinematics in a Multi-Step Activity of Daily Living

Background: Stroke frequently impairs activities of daily living (ADL) and deteriorates the function of the contra- as well as the ipsilesional limbs. In order to analyze alterations of higher motor control unaffected by paresis or sensory loss, the kinematics of ipsilesional upper limb movements in patients with stroke has previously been analyzed during prehensile movements and simple tool use actions. By contrast, motion recording of multi-step ADL is rare and patient-control comparisons for movement kinematics are largely lacking. Especially in clinical research, objective quantification of complex externally valid tasks can improve the assessment of neurological impairments. Methods: In this preliminary study we employed three-dimensional motion recording and applied kinematic analysis in a multi-step ADL (tea-making). The trials were examined with respect to errors and sub-action structure, durations, path lengths (PLs), peak velocities, relative activity (RA) and smoothness. In order to check for specific burdens the sub-actions of the task were extracted and compared. To examine the feasibility of the approach, we determined the behavioral and kinematic metrics of the (ipsilesional) unimanual performance of seven chronic stroke patients (64a ± 11a, 3 with right/4 with left brain damage (LBD), 2 with signs of apraxia, variable severity of paresis) and compared the results with data of 14 neurologically healthy age-matched control participants (70a ± 7a). Results: T-tests revealed that while the quantity and structure of sub-actions of the task were similar. The analysis of end-effector kinematics was able to detect clear group differences in the associated parameters. Specifically, trial duration (TD) was increased (Cohen's d = 1.77); the RA (Cohen's d = 1.72) and the parameters of peak velocities (Cohen's d = 1.49/1.97) were decreased in the patient group. Analysis of the task's sub-actions repeated measures analysis of variance (rmANOVA) revealed no impact of the different demands of the sub-actions on the relative performance of the patient group. Conclusion: The analyses revealed kinematic peculiarities in the performance with the ipsilesional hand. These deficits apparently arose from the cognitive demands like sequencing rather than motor constraints. End-effector kinematics proved as a sensitive method to detect and quantify aspects of disturbed multi-step ADL performance after stroke. If standardized, the examination and the analysis are quick and deliver objective data supporting clinical research.

Movement Kinematics of the Ipsilesional Upper Extremity in Persons With Moderate or Mild Stroke

BACKGROUND

An increasing number of studies have indicated that the ipsilesional arm may be impaired after stroke. There is, however, a lack of knowledge whether ipsilesional deficits influence movement performance during purposeful daily tasks.

OBJECTIVE

The aim of this study was to investigate whether, and to what extent, movement impairments are present while performing an ipsilesional upper extremity task during the first 3 months after stroke.

METHODS

Movement kinematics describing movement time, smoothness, velocity, strategy, and pattern were captured during a standardized drinking task in 40 persons with first-ever stroke and 20 controls. Kinematics were measured early and at 3 months poststroke, and sensorimotor impairment was assessed with Fugl-Meyer Assessment in stroke.

RESULTS

Half of the ipsilesional kinematics showed significant deficits early after stroke compared to controls, and the stroke severity had a significant impact on the kinematics. Movements of the ipsilesional arm were slower, less smooth, demonstrated prolonged relative time in deceleration, and increased arm abduction during drinking. Kinematics improved over time and reached a level comparable with controls at 3 months, except for angular velocity of the elbow and deceleration time in reaching for those with more severe motor impairment.

CONCLUSIONS

This study demonstrates that movements of the ipsilesional arm, during a purposeful daily task, are impaired after stroke. These deficits are more prominent early after stroke and when the motor impairment is more severe. In clinical studies and praxis, the use of less-affected arm as a reference may underestimate the level of impairment and extent of recovery.

An affordable, adaptable, and hybrid assistive device for upper-limb neurorehabilitation

The paper presents a multisensory and multimodal device for neuromuscular rehabilitation of the upper limb, designed to enable enriched rehabilitation treatment in both clinical and home environments. Originating from an existing low-cost, variable-stiffness rehabilitation device, it expands its functionalities by integrating additional modules in order to augment application scenarios and applicable clinical techniques. The newly developed system focuses on the integration of a wearable neuromuscular electrical stimulation system, a virtual rehabilitation scenario, a low-cost unobtrusive sensory system and a patient model for adapting training task parameters. It also monitors the user behavior during each single session and its evolution throughout the entire training period. The result is a modular, integrated and affordable rehabilitation device, enabling a biomechanical, neurological, and physiological-based training of patients, including innovative features currently unavailable within off-the-shelf rehabilitation devices.

Instrumental indices for upper limb function assessment in stroke patients: a validation study

Background

Robotic exoskeletons are increasingly being used in objective and quantitative assessment of upper limb (UL) movements. A set of instrumental indices computed during robot-assisted reaching tasks with the Armeo®Spring has been proven to assess UL functionality. The aim of this study was to test the construct validity of this indices-based UL assessment when used with patients who have had a stroke.

Methods

Forty-four 45- to 79-year-old stroke patients with a Wolf Motor Function Test ability score (WMFT-FAS) ranging from 10 to 75 and a Motricity Index (MI) ranging from 14 to 33 at shoulder and elbow were enrolled, thus covering a wide range of impairments. Residual UL function was assessed by both the WMFT-FAS and the WMFT-TIME, as well as by a set of 9 numerical indices assessing movement accuracy, velocity and smoothness computed from a 3D endpoint trajectory obtained during the “Vertical Capture” task of the Armeo®Spring device. To explore which variables better represented motor control deficits, the Mann-Whitney U Test was used to compare patients’ indices to those obtained from 25 healthy individuals. To explore the inner relationships between indices and construct validity in assessing accuracy, velocity and smoothness, a factor analysis was carried out. To verify the indices concurrent validity, they were compared to both WMFT-FAS and WMFT-TIME by the Spearman’s correlation coefficient.

Results

Seven indices of stroke subjects were significantly different from those of healthy controls, with effect sizes in the range 0.35–0.74. Factor analysis confirmed that specific subsets of indices belonged to the domains of accuracy, velocity and smoothness (discriminant validity). One accuracy index, both velocity indices and two smoothness indices were significantly correlated with WMFT-FAS and WMFT-TIME (|rho| = 0.31–0.50) (concurrent validity). One index for each of the assessed movement domains was proven to have construct validity (discriminant and concurrent) and was selected. Moreover, the indices were able to detect differences in accuracy, velocity and/or smoothness in patients with the same WMFT level.

Conclusions

The proposed index-based UL assessment can be used to integrate and support clinical evaluation of UL function in stroke patients.

Brain activation is related to smoothness of upper limb movements after stroke

It is unclear whether additionally recruited sensorimotor areas in the ipsilesional and contralesional hemisphere and the cerebellum can compensate for lost neuronal functions after stroke. The objective of this study was to investigate how increased recruitment of secondary sensorimotor areas is associated with quality of motor control after stroke. In seventeen patients (three females, fourteen males; age: 59.9 ± 12.6 years), cortical activation levels were determined with functional magnetic resonance imaging (fMRI) in 12 regions of interest during a finger flexion–extension task in weeks 6 and 29 after stroke. At the same time points and by using 3D kinematics, the quality of motor control was assessed by smoothness of the grasp aperture during a reach-to-grasp task, quantified by normalized jerk. Ipsilesional premotor cortex, insula and cerebellum, as well as the contralesional supplementary motor area, insula and cerebellum, correlated significantly and positively with the normalized jerk of grasp aperture at week 6 after stroke. A positive trend towards this correlation was observed in week 29. This study suggests that recruitment of secondary motor areas at 6 weeks after stroke is highly associated with increased jerk during reaching and grasping. As jerk represents the change in acceleration, the recruitment of additional sensorimotor areas seems to reflect a type of control in which deviations from an optimal movement pattern are continuously corrected. This relationship suggests that additional recruitment of sensorimotor areas after stroke may not correspond to restitution of motor function, but more likely to adaptive motor learning strategies to compensate for motor impairments.

Compensatory Versus Noncompensatory Shoulder Movements Used for Reaching in Stroke

Background The extent to which the upper-limb flexor synergy constrains or compensates for arm motor impairment during reaching is controversial. This synergy can be quantified with a minimal marker set describing movements of the arm-plane. Objectives To determine whether and how (a) upper-limb flexor synergy in patients with chronic stroke contributes to reaching movements to different arm workspace locations and (b) reaching deficits can be characterized by arm-plane motion. Methods Sixteen post-stroke and 8 healthy control subjects made unrestrained reaching movements to targets located in ipsilateral, central, and contralateral arm workspaces. Arm-plane, arm, and trunk motion, and their temporal and spatial linkages were analyzed. Results Individuals with moderate/severe stroke used greater arm-plane movement and compensatory trunk movement compared to those with mild stroke and control subjects. Arm-plane and trunk movements were more temporally coupled in stroke compared with controls. Reaching accuracy was related to different segment and joint combinations for each target and group: arm-plane movement in controls and mild stroke subjects, and trunk and elbow movements in moderate/severe stroke subjects. Arm-plane movement increased with time since stroke and when combined with trunk rotation, discriminated between different subject groups for reaching the central and contralateral targets. Trunk movement and arm-plane angle during target reaches predicted the subject group. Conclusions The upper-limb flexor synergy was used adaptively for reaching accuracy by patients with mild, but not moderate/severe stroke. The flexor synergy, as parameterized by the amount of arm-plane motion, can be used by clinicians to identify levels of motor recovery in patients with stroke.