Influence of the side of brain damage on postural upper-limb control including the scapula in stroke patients

Stroke impairs the control of isometric forces and muscle activations in the ipsilesional arm

Stroke often impairs the control of the contralesional arm, thus most survivors rely on the ipsilesional arm to perform daily living activities that require an efficient control of movements and forces. Whereas the ipsilesional arm is often called 'unaffected' or 'unimpaired', several studies suggested that during dynamic tasks its kinematics and joint torques are altered. Is stroke also affecting the ability of the ipsilesional arm to produce isometric force, as when pushing or pulling a handle? Here, we address this question by analyzing behavioral performance and muscles' activity when subjects applied an isometric force of 10 N in eight coplanar directions. We found that stroke affected the ability to apply well-controlled isometric forces with the ipsilesional arm, although to a minor extent compared to the contralesional arm. The spinal maps, the analysis of single muscle activities and the organization of muscle synergies highlighted that this effect was mainly associated with abnormal activity of proximal muscles with respect to matched controls, especially when pushing or pulling in lateral directions.

Intention Prediction and Human Health Condition Detection in Reaching Tasks with Machine Learning Techniques

Detecting human motion and predicting human intentions by analyzing body signals are challenging but fundamental steps for the implementation of applications presenting human–robot interaction in different contexts, such as robotic rehabilitation in clinical environments, or collaborative robots in industrial fields. Machine learning techniques (MLT) can face the limit of small data amounts, typical of this kind of applications. This paper studies the illustrative case of the reaching movement in 10 healthy subjects and 21 post-stroke patients, comparing the performance of linear discriminant analysis (LDA) and random forest (RF) in: (i) predicting the subject’s intention of moving towards a specific direction among a set of possible choices, (ii) detecting if the subject is moving according to a healthy or pathological pattern, and in the case of discriminating the damage location (left or right hemisphere). Data were captured with wearable electromagnetic sensors, and a sub-section of the acquired signals was required for the analyses. The possibility of detecting with which arm (left or right hand) the motion was performed, and the sensitivity of the MLT to variations in the length of the signal sub-section were also evaluated. LDA and RF prediction accuracies were compared: Accuracy improves when only healthy subjects or longer signals portions are considered up to 11% and at least 10%, respectively. RF reveals better estimation performance both as intention predictor (on average 59.91% versus the 62.19% of LDA), and health condition detector (over 90% in all the tests).

Effects of elastic tape on kinematic parameters during a functional task in chronic hemiparetic subjects: A randomized sham-controlled crossover trial

Background

Approximately 50 to 70% of post-stroke subjects present a reduction in the upper limb (UL) function even during the chronic phase. An adjuvant technique widely used in neurorehabilitation is elastic taping applications. However, its efficacy in UL treatment for post-stroke subjects still requires further investigation.

Objective

To verify the effects of elastic tape (ET) used on the paretic shoulder in upper limb (UL) performance during a drinking task.

Method

A single-center randomized sham-controlled crossover trial randomized thirteen post-stroke subjects with mild to moderate UL impairment for group allocation to receive first Sham Tape (ST) or first Elastic Tape (ET), with one month of washout. Kinematic measures of a drinking task were taken before and after each intervention (elastic and sham tape), using Three-Dimensional Motion Analysis, and studied using feature analysis and Statistical Parametric Mapping. Outcome measures included spatiotemporal variables, scalar kinematic parameters (starting angles, range of motion—ROM, and endpoint angles) and time-normalized kinematic waveforms of trunk and UL joint angles (scapulothoracic, humerothoracic and elbow).

Results

Elastic tape provided common modifications throughout the task (shoulder more towards midline, reduced scapula protraction and trunk flexion) and important alterations at specific time-instants. At the end of the reaching phase, for both groups (ET and ST), the elastic tape increased elbow extension [ET: CI = 12.57 (6.90 to 18.17), p<0.001; ST: CI: 12.89 (6.79 to 18.98), p<0.001). At the end of transporting the glass to the mouth, patients who underwent the elastic tape intervention presented more shoulder elevation [ET: CI = 16.40 (4.28 to 28.52), p = 0.007; ST: CI: 15.13 (5.79 to 24.48), p = 0.002)]. Moreover, an increase of elbow extension at the end of transporting the glass to the table was observed for both groups [ET: CI = 8.13 (1.48 to 14.79), p = 0.014; ST: CI: 8.20 (4.03 to 12.38), p<0.001)]. However, no changes in the spatiotemporal parameters were observed for both groups during all the phases of the task (p>0.05).

Conclusion

The ET changed UL joint motions and posture during a drinking task in chronic hemiparetic subjects, which defines its role as an adjuvant therapy.

Kinematic Components of the Reach-to-Target Movement After Stroke for Focused Rehabilitation Interventions: Systematic Review and Meta-Analysis

Background: Better upper limb recovery after stroke could be achieved through tailoring rehabilitation interventions directly at movement deficits. Aim: To identify potential; targets for therapy by synthesizing findings of differences in kinematics and muscle activity between stroke survivors and healthy adults performing reach-to-target tasks. Methods: A systematic review with identification of studies, data extraction, and potential risk of bias was completed independently by two reviewers. Online databases were searched from their inception to November 2017 to find studies of reach-to-target in people-with-stroke and healthy adults. Potential risk-of-bias was assessed using the Down's and Black Tool. Synthesis was undertaken via: (a) meta-analysis of kinematic characteristics utilizing the standardized mean difference (SMD) [95% confidence intervals]; and (b), narrative synthesis of muscle activation. Results: Forty-six studies met the review criteria but 14 had insufficient data for extraction. Consequently, 32 studies were included in the meta-analysis. Potential risk-of-bias was low for one study, unclear for 30, and high for one. Reach-to-target was investigated with 618 people-with-stroke and 429 healthy adults. The meta-analysis found, in all areas of workspace, that people-with-stroke had: greater movement times (seconds) e.g., SMD 2.57 [0.89, 4.25]; lower peak velocity (millimeters/second) e.g., SMD -1.76 [-2.29, -1.24]; greater trunk displacement (millimeters) e.g. SMD 1.42 [0.90, 1.93]; a more curved reach-path-ratio e.g., SMD 0.77 [0.32, 1.22] and reduced movement smoothness e.g., SMD 0.92 [0.32, 1.52]. In the ipsilateral and contralateral workspace, people-with-stroke exhibited: larger errors in target accuracy e.g., SMD 0.70 [0.39, 1.01]. In contralateral workspace, stroke survivors had: reduced elbow extension and shoulder flexion (degrees) e.g., elbow extension SMD -1.10 [-1.62, -0.58] and reduced shoulder flexion SMD -1.91 [-1.96, -0.42]. Narrative synthesis of muscle activation found that people-with-stroke, compared with healthy adults, exhibited: delayed muscle activation; reduced coherence between muscle pairs; and use of a greater percentage of muscle power. Conclusions: This first-ever meta-analysis of the kinematic differences between people with stroke and healthy adults performing reach-to-target found statistically significant differences for 21 of the 26 comparisons. The differences identified and values provided are potential foci for tailored rehabilitation interventions to improve upper limb recovery after stroke.

Asymmetry and Structure of the Fronto-Parietal Networks Underlie Visuomotor Processing in Humans

Research in both humans and monkeys has shown that even simple hand movements require cortical control beyond primary sensorimotor areas. An extensive functional neuroimaging literature demonstrates the key role that cortical fronto-parietal regions play for movements such as reaching and reach-to-grasp. However, no study so far has examined the specific white matter connections linking the fronto-parietal regions, namely the 3 parallel pathways of the superior longitudinal fasciculus (SLF). The aim of the current study was to explore how selective fronto-parietal connections are for different kinds of hand movement in 30 right-handed subjects by correlating diffusion imaging tractography and kinematic data. We showed that a common network, consisting of bilateral SLF II and SLF III, was involved in both reaching and reach-to-grasp movements. Larger SLF II and SLF III in the right hemisphere were associated with faster speed of visuomotor processing, while the left SLF II and SLF III played a role in the initial movement trajectory control. Furthermore, the right SLF II was involved in the closing grip phase necessary for efficient grasping of the object. We demonstrated for the first time that individual differences in asymmetry and structure of the fronto-parietal networks were associated with visuomotor processing in humans.

Kinematic Analysis of a Drinking Task in Chronic Hemiparetic Patients Using Features Analysis and Statistical Parametric Mapping

OBJECTIVE

To compare sitting posture and movement strategies between chronic hemiparetic and healthy subjects while performing a drinking task, using statistical parametric mapping (SPM) and feature analysis.

DESIGN

Cross-sectional study.

SETTING

A university physical therapy department.

PARTICIPANTS

Participants (N=26) consisted of chronic hemiparetic (n=13) and healthy individuals (n=13) matched for sex and age.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The drinking task was divided into phases: reaching, transporting the glass to mouth, transporting the glass to table, and returning to initial position. An SPM 2-sample t test was used to compare the entire kinematic waveforms of different joint angles (trunk, scapulothoracic, humerothoracic, elbow). Joint angles at the beginning and end of the motion, movement time, peak velocity timing, trajectory deviation, normalized integrated jerk, and range of motion were extracted from the motion data. Group differences for these parameters were analyzed using independent t tests.

RESULTS

At the static posture and beginning of the reaching phase, patients showed a shoulder position more deviated from the midline and externally rotated with increased scapula protraction, medial rotation, anterior tilting, trunk anterior flexion and inclination to the paretic side. Altered spatiotemporal variables throughout the task were found in all phases, except for the returning phase. Patients returned to a similar posture as the task onset, except for the scapula, which was normalized after the reaching phase.

CONCLUSIONS

Chronic hemiparetic subjects showed more deviations in the proximal joints during seated posture and reaching. However, the scapular movement drew nearer to the healthy individuals' patterns after the first phase, showing an interesting point to consider in rehabilitation programs.

Variability, frequency composition, and temporal regularity of submaximal isometric elbow flexion force in subacute stroke

We compared variability, frequency composition, and temporal regularity of submaximal isometric elbow flexion force at 10, 20, 35, and 50 % of peak torque between 34 stroke subjects (5-48 days post-onset, both arms) and 24 age-matched controls (dominant arm), and related the findings in the paretic arm to motor impairment. Force variability was quantified by the coefficient of variation (CV), frequency composition by the median frequency and relative power in 0-3-, 4-6-, and 8-12-Hz bands, and regularity by the sample entropy (SampEn). The paretic elbow flexors showed significantly increased CV and relative power in 0-3-Hz band, decreased power in 4-6- and 8-12-Hz bands, and decreased SampEn compared to both the non-paretic and control elbow flexors (P ≤ 0.0002), with no differences between the latter two (P ≥ 0.012). With increasing contraction intensity, the relative power in different frequency bands was insufficiently modulated and SampEn excessively decreased in the paretic elbow flexors. Also, CV in the paretic elbow flexors was non-linearly related to the relative power in different frequency bands and SampEn across contraction intensities (rectangular hyperbolic fit, 0.21 ≤ R ² ≤ 0.55, P ≤ 0.006), whereas no force parameter correlated with arm motor impairment. These results largely extend our previous findings in the paretic knee extensors to the elbow flexors in subacute stroke, except that here force variability was increased only in the paretic elbow flexors and modulation of force regularity with increasing contraction intensity showed the opposite, decreasing pattern, which was considerably exaggerated in the paretic muscles.

Three-dimensional kinematics of the scapula and trunk, and associated scapular muscle timing in individuals with stroke

Poor scapulothoracic control is a risk for developing shoulder pathology, but has received little attention so far in individuals with stroke (IwS). Trunk and scapular kinematics and surface muscle activity were measured in 15 healthy controls and 18 IwS during a low and high forward flexion (FF). Group-differences in trunk and scapular kinematics were assessed during low and high FF using a t-test (independent samples). Differences in muscle onset and offset time relative to movement start (both FF tasks) were determined using a mixed model taking into account the different groups and muscles. Recruitment patterns per group and task were described based on significant differences between muscles. In IwS, earlier lower trapezius and late infraspinatus offset were found during low FF, as well as a later onset and earlier offset of serratus anterior. For low FF, significantly more trunk axial rotation was found in IwS during both elevation and lowering. During high FF, IwS showed significantly less scapular posterior tilt during elevation and more scapular lateral rotation during lowering. IwS demonstrated adaptive muscle timing with earlier initiation and late inactivation of lower trapezius and infraspinatus, possibly to compensate for a late activation and early deactivation of the serratus anterior and to establish as such the correct pattern of scapulothoracic movement.

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.

Effect of motor training involving the less-affected side (MTLA) in post-stroke subjects: a pilot randomized controlled trial

INTRODUCTION

Poststroke, less-severe motor impairment occurs on the ipsilesional side of body. The objective of the present study was to evaluate the effectiveness of the motor training involving the less-affected side (MTLA) in stroke.

METHODS

This was a randomized, controlled, double-blinded pilot study conducted in the occupational therapy unit of a rehabilitation Institute. A convenience sample of 35 stroke subjects (mean poststroke duration, 28.76 weeks) was randomized into two groups (the experimental group: 17 and control group: 18). Thirty-two participants completed the entire study protocol. The experimental group and control group were provided MTLA and neurophysiological-based conventional therapy respectively. Both the groups received 24 treatment sessions (60 minutes each) over the period of two months. The Affected side was assessed using Brunnstrom recovery stage (BRS) and Fugl-Meyer assessment (FMA) whereas the less-affected side was evaluated by Minnesota manual dexterity test (MMDT), Purdue peg board test (PPBT) and Manual Muscle Testing (MMT).

RESULTS

Postintervention, the less-affected side of experimental group demonstrated significant improvement for MMDT (P = 0.003), PPBT (P = 0.01) and MMT (P <  0.001 to 0.043) in comparison to the control group. Further, as compared to the control group, the experimental group exhibited positive significant change for the measure of affected side [BRS (P <  0.001) and FMA (P <  0.001 to 0.03)] at post assessment.

CONCLUSION

MTLA enhanced the muscle strength, dexterity and coordination of the less-affected side as well as the motor recovery of the affected side in poststroke hemiparetic subjects.

Specific scapular kinematic patterns to differentiate two forms of dynamic scapular winging

BACKGROUND

Dynamic scapular winging (DSW) is a rare and misdiagnosed disorder causing considerable disability due to reduced scapular stability and abnormal motion. Two common causes are long thoracic nerve lesions resulting in serratus anterior muscle palsy and spinal accessory nerve lesions resulting in trapezius muscle palsy. The aim of this study was to analyse 3D scapular kinematic patterns in patients with DSW due to long thoracic (LTNL) or spinal accessory nerve lesions (SANL).

METHODS

3D scapular kinematics were assessed using a non invasive method involving an electromagnetic device during arm elevation in the frontal and sagittal planes in 9 patients (4 with SANL and 5 with LTNL) with unilateral DSW confirmed by electrical evidence. Within subject affected-unaffected differences were measured and compared between pathological groups (Mann-Whitney).

FINDINGS

Differences between affected and unaffected shoulders were significantly greater for scapular posterior tilt (at rest and 30° for sagittal arm elevation, at rest, 30° and 60° for frontal arm elevation) in the LTNL compared to the SANL group. Differences between affected and unaffected shoulders were significantly greater for scapular protraction (at rest and 60° of sagittal arm elevation, at rest, 30° and 60° of frontal arm elevation) and scapular lateral rotation at 60° for frontal arm elevation in the SANL compared to the LTNL group.

INTERPRETATIONS

These kinematic findings show two different scapular patterns that are specific to the neurological lesion. Moreover our kinematic data relate to specific clinical signs and the functional roles of the muscles involved.

Motor recovery of the ipsilesional upper limb in subacute stroke

OBJECTIVE

To investigate the time-related changes in motor performance of the ipsilesional upper limb in subacute poststroke patients by using clinical and kinematic assessments.

DESIGN

Observational, longitudinal, prospective, monocentric study.

SETTING

Physical medicine and rehabilitation department.

PARTICIPANTS

Stroke patients (n=19; mean age, 62.9y) were included less than 30 days after a first unilateral ischemic/hemorrhagic stroke. The control group was composed of age-matched, healthy volunteers (n=9; mean age, 63.1y).

INTERVENTIONS

Clinical and kinematic assessments were conducted once a week during 6 weeks and 3 months after inclusion. Clinical measures consisted of Fugl-Meyer Assessment, Box and Block Test (BBT), Nine-Hole Peg Test (9HPT), and Barthel Index. We used a 3-dimensional motion recording system during a reach-to-grasp task to analyze movement smoothness, movement time, and peak velocity of the hand. Healthy controls performed both clinical (BBT and 9HPT) and kinematic evaluation within a single session.

MAIN OUTCOME MEASURES

BBT and 9HPT.

RESULTS

Recovery of ipsilesional upper arm capacities increased over time and leveled off after a 6-week period of rehabilitation, corresponding to 9 weeks poststroke. At study discharge, patients demonstrated similar ipsilesional clinical scores to controls but exhibited less smooth reaching movements. We found no effect of the hemispheric side of the lesion on ipsilesional motor deficits.

CONCLUSIONS

Our findings provide evidence that ipsilesional motor capacities remain impaired at least 3 months after stroke, even if clinical tests fail to detect the impairment. Focusing on this lasting ipsilesional impairment through a more detailed kinematic analysis could be of interest to understand the specific neural network underlying ipsilesional upper-limb impairment.

Contralesional motor deficits after unilateral stroke reflect hemisphere-specific control mechanisms

We have proposed a model of motor lateralization, in which the left and right hemispheres are specialized for different aspects of motor control: the left hemisphere for predicting and accounting for limb dynamics and the right hemisphere for stabilizing limb position through impedance control mechanisms. Our previous studies, demonstrating different motor deficits in the ipsilesional arm of stroke patients with left or right hemisphere damage, provided a critical test of our model. However, motor deficits after stroke are most prominent on the contralesional side. Post-stroke rehabilitation has also, naturally, focused on improving contralesional arm impairment and function. Understanding whether contralesional motor deficits differ depending on the hemisphere of damage is, therefore, of vital importance for assessing the impact of brain damage on function and also for designing rehabilitation interventions specific to laterality of damage. We, therefore, asked whether motor deficits in the contralesional arm of unilateral stroke patients reflect hemisphere-dependent control mechanisms. Because our model of lateralization predicts that contralesional deficits will differ depending on the hemisphere of damage, this study also served as an essential assessment of our model. Stroke patients with mild to moderate hemiparesis in either the left or right arm because of contralateral stroke and healthy control subjects performed targeted multi-joint reaching movements in different directions. As predicted, our results indicated a double dissociation; although left hemisphere damage was associated with greater errors in trajectory curvature and movement direction, errors in movement extent were greatest after right hemisphere damage. Thus, our results provide the first demonstration of hemisphere specific motor control deficits in the contralesional arm of stroke patients. Our results also suggest that it is critical to consider the differential deficits induced by right or left hemisphere lesions to enhance post-stroke rehabilitation interventions.