Motor-Equivalent Intersegmental Coordination Is Impaired in Chronic Stroke

AiCarePWP: Deep learning-based novel research for Freezing of Gait forecasting in Parkinson

BACKGROUND AND OBJECTIVES

Episodes of Freezing of Gait (FoG) are among the most debilitating motor symptoms of Parkinson's Disease (PD), leading to falls and significantly impacting patients' quality of life. Accurate assessment of FoG by neurologists provides crucial insights into patients' conditions and disease symptoms. This proposed strategy involves utilizing a Weighted Fuzzy Logic Controller, Kalman Filter, and Kaiser-Meyer-Olkin test to detect the gait parameters while walking, resting, and standing phases. Parameters such as neuromodulation format, intensity, duration, frequency, and velocity are computed to pre-empt freezing episodes, thus aiding their prevention.

METHOD

The AiCarePWP is a wearable electronics device designed to identify instances when a patient is on the brink of experiencing a freezing episode and subsequently deliver a brief electrical impulse to the patient's shank muscles to stimulate movement. The AiCarePWP wearable device aims to identify impending freezing episodes in PD patients and deliver brief electrical impulses to stimulate movement. The study validates this innovative approach using plantar insoles with a 3D accelerometer and electrical stimulator, analysing data from the inertial measuring unit and plantar-pressure foot data to detect and predict FoG.

RESULTS

Using a Convolutional Neural Network-based model, the study evaluated 47 gait features for their ability to differentiate resting, standing, and walking conditions. Variable selection was based on sensitivity, specificity, and overall accuracy, followed by Principal Component Analysis and Varimax rotation to extract and interpret factors. Factors with eigenvalues exceeding 1.0 were retained, and 37 features were retained.

CONCLUSION

This study validates CNN's effectiveness in detecting FoG during various activities. It introduces a novel cueing method using electrical stimulation, which improves gait function and reduces FoG incidence in PD patients. Trustworthy wearable devices, based on Artificial Intelligence of Things (AIoT) and Artificial Intelligence of Medical Things (AIoMT), have been developed to support such interventions.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

Altered Anticipatory Postural Adjustments During Whole-Body Reaching in Subjects With Stroke

BACKGROUND

Coordination between arm movements and postural adjustments is crucial for reaching-while-stepping tasks involving both anticipatory postural adjustments (APAs) and compensatory movements to effectively propel the whole-body forward so that the hand can reach the target. Stroke impairs the ability to coordinate the action of multiple body segments but the underlying mechanisms are unclear. Objective. To determine the effects of stroke on reaching performance and APAs during whole-body reaching.

METHODS

We tested arm reaching in standing (stand-reach) and reaching-while-stepping (step-reach; 15 trials/condition) in individuals with chronic stroke (n = 18) and age-matched healthy subjects (n = 13). Whole-body kinematics and kinetic data were collected during the tasks. The primary outcome measure for step-reach was "gain" (g), defined as the extent to which the hip displacement contributing to hand motion was neutralized by appropriate changes in upper limb movements (g = 1 indicates complete compensation) and APAs measured as spatio-temporal profiles of the center-of-pressure shifts preceding stepping.

RESULTS

Individuals with stroke had lower gains and altered APAs compared to healthy controls. In addition, step onset was delayed, and the timing of endpoint, trunk, and foot movement offset was prolonged during step-reach compared to healthy controls. Those with milder sensorimotor impairment and better balance function had higher gains. Altered APAs were also related to reduced balance function.

CONCLUSIONS

Altered APAs and prolonged movement offset in stroke may lead to a greater reliance on compensatory arm movements. Altered APAs in individuals with stroke may be associated with a reduced shift of referent body configuration during the movement.

Quantitative Assessment of Upper Limb Movement in Post-Stroke Adults for Identification of Sensitive Measures in Reaching and Lifting Activities

BACKGROUND

The assumption of this work is the achievement of objective results of the movement structure, which forms the basis for in-depth analysis and, consequently, for determining the upper limb movements that are most affected by stroke compared to healthy people.

METHODS

An analysis of relevant and systematically identified features of upper limb movement in post-stroke adults is presented based on scalable hypothesis tests. The basic features were calculated using movements defined by the x, y, and z coordinates (i.e., 3D trajectory time series) and compared to the results of post-stroke patients with healthy controls of similar age.

RESULTS

After automatic feature selection, out of the 1004 common features of upper limb movement, the most differentiated were the upper arm movements in reaching kinematics. In terms of movement type, movements in the frontal plane (shoulder abduction and adduction) were the most sensitive to changes. The largest number of discriminating features was determined on the basis of acceleration time series.

CONCLUSIONS

In the 3D assessment of functional activities of the upper limb, the upper arm turned out to be the most differentiated body segment, especially during abduction and adduction movements. The results indicate a special need to pay attention to abduction and adduction movements to improve the activities of daily living of the upper limbs after a stroke.

Identification of inverse kinematic parameters in redundant systems: Towards quantification of inter-joint coordination in the human upper extremity

Understanding and quantifying inter-joint coordination is valuable in several domains such as neurorehabilitation, robot-assisted therapy, robotic prosthetic arms, and control of supernumerary arms. Inter-joint coordination is often understood as a consistent spatiotemporal relation among kinematically redundant joints performing functional and goal-oriented movements. However, most approaches in the literature to investigate inter-joint coordination are limited to analysis of the end-point trajectory or correlation analysis of the joint rotations without considering the underlying task; e.g., creating a desirable hand movement toward a goal as in reaching motions. This work goes beyond this limitation by taking a model-based approach to quantifying inter-joint coordination. More specifically, we use the weighted pseudo-inverse of the Jacobian matrix and its associated null-space to explain the human kinematics in reaching tasks. We propose a novel algorithm to estimate such Inverse Kinematics weights from observed kinematic data. These estimated weights serve as a quantification for spatial inter-joint coordination; i.e., how costly a redundant joint is in its contribution to creating an end-effector velocity. We apply our estimation algorithm to datasets obtained from two different experiments. In the first experiment, the estimated Inverse Kinematics weights pinpoint how individuals change their Inverse Kinematics strategy when exposed to the viscous field wearing an exoskeleton. The second experiment shows how the resulting Inverse Kinematics weights can quantify a robotic prosthetic arm's contribution (or the level of assistance).

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

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

The reserve of joint torque determines movement coordination

Humans coordinate biomechanical degrees of freedom to perform tasks at minimum cost. When reaching a target from a seated position, the trunk-arm-forearm coordination moves the hand to the well-defined spatial goal, while typically minimising hand jerk and trunk motion. However, due to fatigue or stroke, people visibly move the trunk more, and it is unclear what cost can account for this. Here we show that people recruit their trunk when the torque at the shoulder is too close to the maximum. We asked 26 healthy participants to reach a target while seated and we found that the trunk contribution to hand displacement increases from 11 to 27% when an additional load is handled. By flexing and rotating the trunk, participants spontaneously increase the reserve of anti-gravitational torque at the shoulder from 25 to 40% of maximal voluntary torque. Our findings provide hints on how to include the reserve of torque in the cost function of optimal control models of human coordination in healthy fatigued persons or in stroke victims.

Age-related changes in upper limb coordination in a complex reaching task

When reaching to targets within arm's reach, intentional trunk motion must be neutralized by compensatory motion of the upper limb (UL). Advanced age has been associated with deterioration in the coordination of multi-joint UL movements. In the current study, we looked to determine if older adults also have difficulties modifying their UL movements (i.e., coordination between the shoulder and elbow joints), during a complex reaching task when trunk motion is manipulated. Two groups of healthy participants were recruited: 18 young (mean age = 24.28 ± 2.89 years old) and 18 older (mean age = 72.11 ± 2.39 years old) adults. Participants reached to a target with their eyes closed, while simultaneously moving the trunk forward. In 40% of trials, the trunk motion was unexpectedly blocked. Participants performed the task with both their dominant and non-dominant arms, and at a preferred and fast speed. All participants were able to coordinate motion at the elbow and shoulder joints in a similar manner and modify this coordination in accordance with motion at the trunk, regardless of the hand used or speed of movement. Specifically, in reaches that involved forward trunk motion (free-trunk trials), all participants demonstrated increased elbow flexion (i.e., less elbow extension) compared to blocked-trunk trials. In contrast, when trunk motion was blocked (blocked-trunk trials), all reaching movements were accompanied by increased shoulder horizontal adduction. While coordination of UL joints was similar across older and young adults, the extent of changes at the elbow and shoulder was smaller and less consistent in older adults compared to young participants, especially when trunk motion was involved. These results suggest that older adults can coordinate their UL movements based on task requirements, but that their performance is not as consistent as young adults.

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.

Mild Stroke Affects Pointing Movements Made in Different Frames of Reference

Background

Motor performance is a complex process controlled in task-specific spatial frames of reference (FRs). Movements can be made within the framework of the body (egocentric FR) or external space (exocentric FR). People with stroke have impaired reaching, which may be related to deficits in movement production in different FRs.

Objective

To characterize rapid motor responses to changes in the number of degrees of freedom for movements made in different FRs and their relationship with sensorimotor and cognitive impairment in individuals with mild chronic stroke.

Methods

Healthy and poststroke individuals moved their hand along the contralateral forearm (egocentric task) and between targets in the peripersonal space (exocentric task) without vision while flexing the trunk. Trunk movement was blocked in randomized trials.

Results

For the egocentric task, controls produced the same endpoint trajectories in both conditions (free- and blocked-trunk) by preserving similar shoulder-elbow interjoint coordination (IJC). However, endpoint trajectories were dissimilar because of altered IJC in stroke. For the exocentric task, controls produced the same endpoint trajectories when the trunk was free or blocked by rapidly changing the IJC, whereas this was not the case in stroke. Deficits in exocentric movement after stroke were related to cognitive but not sensorimotor impairment.

Conclusions

Individuals with mild stroke have deficits rapidly responding to changing conditions for complex reaching tasks. This may be related to cognitive deficits and limitations in the regulation of tonic stretch reflex thresholds. Such deficits should be considered in rehabilitation programs encouraging the reintegration of the affected arm into activities of daily living.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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