Quantifying Quality of Reaching Movements Longitudinally Post-Stroke: A Systematic Review.

BACKGROUND: Disambiguation of behavioral restitution from compensation is important to better understand recovery of upper limb motor control post-stroke and subsequently design better interventions. Measuring quality of movement (QoM) during standardized performance assays and functional tasks using kinematic and kinetic metrics potentially allows for this disambiguation. OBJECTIVES: To identify longitudinal studies that used kinematic and/or kinetic metrics to investigate post-stroke recovery of reaching and assess whether these studies distinguish behavioral restitution from compensation. METHODS: A systematic literature search was conducted using the databases PubMed, Embase, Scopus, and Wiley/Cochrane Library up to July 1st, 2020. Studies were identified if they performed longitudinal kinematic and/or kinetic measurements during reaching, starting within the first 6 months post-stroke. RESULTS: Thirty-two longitudinal studies were identified, which reported a total of forty-six different kinematic metrics. Although the majority investigated improvements in kinetics or kinematics to quantify recovery of QoM, none of these studies explicitly addressed the distinction between behavioral restitution and compensation. One study obtained kinematic metrics for both performance assays and a functional task. CONCLUSIONS: Despite the growing number of kinematic and kinetic studies on post-stroke recovery, longitudinal studies that explicitly seek to delineate between behavioral restitution and compensation are still lacking in the literature. To rectify this situation, future studies should measure kinematics and/or kinetics during performance assays to isolate restitution and during a standardized functional task to determine the contributions of restitution and compensation.

Standardized Measurement of Quality of Upper Limb Movement After Stroke: Consensus-Based Core Recommendations From the Second Stroke Recovery and Rehabilitation Roundtable.

The second Stroke Recovery and Rehabilitation Roundtable "metrics" task force developed consensus around the recognized need to add kinematic and kinetic movement quantification to its core recommendations for standardized measurements of sensorimotor recovery in stroke trials. Specifically, we focused on measurement of the quality of upper limb movement. We agreed that the recommended protocols for measurement should be conceptually rigorous, reliable, valid and responsive to change. The recommended measurement protocols include four performance assays (i.e. 2D planar reaching, finger individuation, grip strength, and precision grip at body function level) and one functional task (3D drinking task at activity level) that address body function and activity respectively. This document describes the criteria for assessment and makes recommendations about the type of technology that should be used for reliable and valid movement capture. Standardization of kinematic measurement protocols will allow pooling of participant data across sites, thereby increasing sample size aiding meta-analyses of published trials, more detailed exploration of recovery profiles, the generation of new research questions with testable hypotheses, and development of new treatment approaches focused on impairment. We urge the clinical and research community to consider adopting these recommendations.

Standardized measurement of quality of upper limb movement after stroke: Consensus-based core recommendations from the Second Stroke Recovery and Rehabilitation Roundtable.

The second Stroke Recovery and Rehabilitation Roundtable "metrics" task force developed consensus around the recognized need to add kinematic and kinetic movement quantification to its core recommendations for standardized measurements of sensorimotor recovery in stroke trials. Specifically, we focused on measurement of the quality of upper limb movement. We agreed that the recommended protocols for measurement should be conceptually rigorous, reliable, valid and responsive to change. The recommended measurement protocols include four performance assays (i.e. 2D planar reaching, finger individuation, grip strength, and precision grip at body function level) and one functional task (3D drinking task at activity level) that address body function and activity respectively. This document describes the criteria for assessment and makes recommendations about the type of technology that should be used for reliable and valid movement capture. Standardization of kinematic measurement protocols will allow pooling of participant data across sites, thereby increasing sample size aiding meta-analyses of published trials, more detailed exploration of recovery profiles, the generation of new research questions with testable hypotheses, and development of new treatment approaches focused on impairment. We urge the clinical and research community to consider adopting these recommendations.

Ipsilateral motor dysfunction from unilateral stroke: implications for the functional neuroanatomy of hemiparesis.

BACKGROUND: Motor dysfunction in the contralateral hand has been well characterised after stroke. The ipsilateral hand has received less attention, yet may provide valuable insights into the structure of the motor system and the nature of the recovery process. By tracking motor function of both hands beginning in the acute stroke period in patients with cortical versus subcortical lesions, we sought to understand the functional anatomy of the ipsilateral deficit. METHODS: We examined 30 patients with first-ever unilateral hemiparetic stroke, 23 with subcortical lesions affecting the corticospinal tract, seven with cortical involvement. Patients performed hand dynamometry and the 9-Hole Peg Test (9HPT) with each hand at 24-48 h, 1 week, 3 months and 1 year after stroke. Linear regression was used to compare the two different motor tasks in each hand. Repeated measures ANOVA was used to compare recovery rates of the two tasks in the first 3 months. RESULTS: Ipsilateral 9HPT scores averaged z = -7.1, -3.6, -2.5 and -2.3 at the four time points whereas grip strength was unaffected. The initial degree of impairment of grip strength in the contralateral hand did not correlate with the degree of impairment of 9HPT in either the contralateral or ipsilateral hand (r = 0.001, p = 0.98), whereas the initial degree of impairment of 9HPT in the contralateral hand correlated with the degree of impairment of 9HPT in the ipsilateral hand (r = 0.79, p = 0.035). The rate of recovery also differed for the two tasks (p = 0.005). CONCLUSION: Ipsilateral motor deficits are demonstrable immediately after stroke and extend into the subacute and chronic recovery period. Dissociation between grip strength and dexterity support the notion that dexterity and grip strength operate as anatomically and functionally distinct entities. Our findings in patients with subcortical lesions suggest that the model of white matter tract injury needs to be refined to reflect the influence of a subcortical lesion on bi-hemispheral cortical networks, rather than as a simple "severed cable" model of disruption of corticofugal fibres. Our data have implications for both stroke clinical trials and the development of new strategies for therapeutic intervention in stroke recovery.

Variability in language recovery after first-time stroke.

BACKGROUND: Predicting aphasia recovery after stroke has been difficult due to substantial variability in outcomes. Few studies have characterised the nature and extent of recovery, beginning with baselines at 24-72 hours after stroke onset. AIM: To characterise the course of language recovery after first-time stroke. METHODS: Using our Performance and Recovery in Stroke Study (PARIS) database, we evaluated consecutive first-time stroke patients with aphasia and diffusion-weighted-image-positive lesions on admission and at 90 days. RESULTS: Twenty-two of 91 patients had language disorders. Initial syndrome scores were positively correlated with 90-day scores (r = 0.60) and negatively correlated with the change in score from baseline to follow-up (r = -0.66). Neither lesion size, age nor education correlated with initial syndrome severity or with performance at 90 days. Level of education was not associated with degree of recovery. A multiple regression model that combined lesion size, age and initial syndrome was significant (p = 0.03) but only explained 29% of the variance. Patients with severe deficits at baseline in individual language domains could recover, improve to a less severe deficit or not improve at all. CONCLUSION: There was significant variability in language recovery after first-time stroke, even in more severe, initial syndromes. Traditional predictors of post-stroke language outcomes did not reliably predict function at 90 days. These data suggest that other factors that account for functional stroke recovery have not yet been identified.

Reversible leukoencephalopathy associated with cerebral amyloid angiopathy.

The authors describe three patients with reversible leukoencephalopathy associated with cerebral amyloid angiopathy (CAA). Rapid progression of neurologic symptoms was followed by dramatic clinical and radiographic improvement. Pathologically, CAA was associated with varying degrees of inflammation ranging from none to transmural granulomatous infiltration. In the appropriate clinical context, the MRI finding of lobar white matter edema with evidence of prior hemosiderin deposition may indicate the presence of a reversible CAA leukoencephalopathy.

Evolution of cortical activation during recovery from corticospinal tract infarction.

BACKGROUND AND PURPOSE: Recovery from hemiparesis due to corticospinal tract infarction is well documented, but the mechanism of recovery is unknown. Functional MRI (fMRI) provides a means of identifying focal brain activity related to movement of a paretic hand. Although prior studies have suggested that supplementary motor regions in the ipsilesional and contralesional hemisphere play a role in recovery, little is known about the time course of cortical activation in these regions as recovery proceeds. METHODS: Eight patients with first-ever corticospinal tract lacunes causing hemiparesis had serial fMRIs within the first few days after stroke and at 3 to 6 months. Six healthy subjects were used as controls. Statistically significant voxels during a finger-thumb opposition task were identified with an automated image processing program. An index of ipsilateral versus contralateral activity was used to compare relative contributions of the 2 hemispheres to motor function in the acute and chronic phases after stroke. RESULTS: Controls showed expected activation in the contralateral sensorimotor cortex (SMC), premotor, and supplementary motor areas. Stroke patients differed from control patients in showing greater activation in the ipsilateral SMC, ipsilateral posterior parietal, and bilateral prefrontal regions. Compared with the nonparetic hand, the ratio of contralateral to ipsilateral SMC activity during movement of the paretic hand increased significantly over time as the paretic hand regained function. CONCLUSIONS: The evolution of activation in the SMC from early contralesional activity to late ipsilesional activity suggests that a dynamic bihemispheric reorganization of motor networks occurs during recovery from hemiparesis.

Learning of visuomotor transformations for vectorial planning of reaching trajectories.

The planning of visually guided reaches is accomplished by independent specification of extent and direction. We investigated whether this separation of extent and direction planning for well practiced movements could be explained by differences in the adaptation to extent and directional errors during motor learning. We compared the time course and generalization of adaptation with two types of screen cursor transformation that altered the relationship between hand space and screen space. The first was a gain change that induced extent errors and required subjects to learn a new scaling factor. The second was a screen cursor rotation that induced directional errors and required subjects to learn new reference axes. Subjects learned a new scaling factor at the same rate when training with one or multiple target distances, whereas learning new reference axes took longer and was less complete when training with multiple compared with one target direction. After training to a single target, subjects were able to transfer learning of a new scaling factor to previously unvisited distances and directions. In contrast, generalization of rotation adaptation was incomplete; there was transfer across distances and arm configurations but not across directions. Learning a rotated reference frame only occurred after multiple target directions were sampled during training. These results suggest the separate processing of extent and directional errors by the brain and support the idea that reaching movements are planned as a hand-centered vector whose extent and direction are established via learning a scaling factor and reference axes.

Independent learning of internal models for kinematic and dynamic control of reaching.

Psychophysical studies of reaching movements suggest that hand kinematics are learned from errors in extent and direction in an extrinsic coordinate system, whereas dynamics are learned from proprioceptive errors in an intrinsic coordinate system. We examined consolidation and interference to determine if these two forms of learning were independent. Learning and consolidation of two novel transformations, a rotated spatial reference frame and altered intersegmental dynamics, did not interfere with each other and consolidated in parallel. Thus separate kinematic and dynamic models were constructed simultaneously based on errors computed in different coordinate frames, and possibly, in different sensory modalities, using separate working-memory systems. These results suggest that computational approaches to motor learning should include two separate performance errors rather than one.

Stimulus context in hemineglect.

Rightward deviation on bisection of a horizontal line is well described in patients with right brain injury and left hemineglect. Because of the observation that hemineglect patients may bisect very short lines to the left of the true midpoint (the so-called crossover effect), additional models have been proposed to incorporate this finding into existing theories of hemineglect. We investigated a line-length effect in six patients with left hemineglect. When presented with any set of lines of uniform (reference) length, percentage rightward deviation on line bisection remained constant across different line lengths. When lines of a second length were mixed into any uniform set of lines, bisection performance on the reference lines changed. A rightward shift in the perceived midpoint of the reference line occurred if the added lines were shorter than the reference lines; a leftward shift occurred if the added lines were longer. Leftward shifts included shifts across the true midpoint, reproducing the crossover effect. Shifts in the perceived midpoint occurred both on a manual line bisection task and on a line bisection discrimination task in which no manual response was required. We propose that the crossover effect may be part of a more general stimulus-context effect in which the perceived midpoint of a line is related not to absolute length, but to the line's length relative to other lines with which it is presented. Such a context effect has not hitherto been described in the neglect syndrome. A possible mechanism for the effect is a generalization of length estimation produced by the combined influence of the focal stimulus and all stimuli that precede it.

Learning of scaling factors and reference axes for reaching movements.

TO further understand visuomotor transformations in reaching, we compared adaptation to display rotation and altered gain in planar movements. Healthy subjects moved a cursor on a screen by moving an indicator on a horizontal digitizing tablet with their unseen hand. Adaptation to rotation was less complete and was accompanied by markedly increased directional variability. Adaptation training on a single target generalized broadly for gain change, but poorly for rotation. We propose that the difficulty in adapting to rotation arises from the substantial demands on short-term working memory imposed by the need to determine the new reference direction. Adaptation to gain change makes more modest demands on short-term memory to recalibrate the visuomotor scaling factor.