J. Metrot

The contribution of kinematics in the assessment of upper limb motor recovery early after stroke.

Background. Kinematic assessment of upper limb motor recovery after stroke may be related to clinical scores while being more sensitive and reliable than clinical evaluation alone. Objective. To identify the potential of kinematics in assessing upper limb recovery early poststroke. Methods. Thirteen patients were included within 1 month poststroke and evaluated once a week for 6 weeks and at 3 months with (a) the Fugl-Meyer Assessment (FMA) and (b) kinematic analysis of reach-to-grasp movements. The link between clinical and kinematic data was identified using mixed model with random coefficient analysis. Results. Movement time, trajectory length, directness, smoothness, mean and maximum velocity of the hand were sensitive to change over time and distinguished between movements of paretic, nonparetic, and healthy control limbs. The FMA score increased with movement smoothness over time, explaining 62.5% of FMA variability. Conclusion. Kinematic analysis of reach-to-grasp movements is relevant to assess upper limb recovery early poststroke, and is linked to the FMA. Kinematics could provide more accurate real-time indicators of patients’ recovery as compared with the sole use of clinical scores, although it remains challenging to establish the universality of the reaching model in relation to motor recovery after stroke.

Somatosensory-Related Limitations for Bimanual Coordination After Stroke

Background. Bimanual coordinated movements may be impaired after stroke, so an assessment of causes is necessary to optimize rehabilitation strategies. Objective. We assessed the role of afference-based sources of coordination, including phase entrainment and error correction based on visual and somatosensory feedback. Methods. In all, 10 persons with unilateral chronic stroke and 8 age-matched controls participated in a kinesthetic tracking protocol, in which the hemiparetic upper limb was passively driven by the machine. The task consisted of matching the trajectory of the driven limb as accurately as possible with the freely moving limb in 2 conditions: eyes closed and eyes open. We analyzed the continuous relative phase (CRP), the mean absolute difference between positions (ADP) between the positions of the 2 limbs, and the jerk of the matching limb. Results. Coordination instability (CRP standard deviation) and mean ADP were significantly higher for patients with eyes closed, compared with patients with eyes open, controls with eyes closed, and controls with eyes open. Moreover, the jerk was higher for the nonparetic limb of patients than for the control group. Thus, the nonparetic limb did not produce optimally smooth movements even as the motor-driven paretic limb did. Conclusion. Besides deficits caused by interhemispheric competition and motor execution of the paretic limb, somatosensory feedback is a limiting factor in bimanual coordination after stroke. The findings have clinical implications pertaining to the design and individualization of efficient bimanual movement therapy.

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.

People post-stroke perceive movement fluency in virtual reality.

We investigated the visual perception of biological movement by people post-stroke, using minimal kinematic displays. A group of twenty patients and a group of twelve age-matched healthy controls were asked to judge movement fluency. The movements to judge were either displayed as an end-point dot or as a stick-figure of the arm and trunk. It was found that the perception of movement fluency was preserved post-stroke, however, with an increase in the variability of judgment. Moreover, the end-point dot representation ameliorated what was perceived and judged, presumably by directing attention to the important kinematic cues: smoothness and directness of the trajectory. We conclude that, despite perception of actions is influenced by the ability of the observer to execute the observed movement, hemiparesis has a mild effect on the perception of biological movement. Yet, a valuable virtual learning environment for upper-limb rehabilitation should be implemented to provide the observer with neither too much, nor too little information to maximize learning.

Changes in Bimanual Coordination During the First 6 Weeks After Moderate Hemiparetic Stroke

Background. Better understanding of how bimanual coordination changes over the first weeks of recovery after stroke is required to address the potential utility for bimanual rehabilitation. Three-dimensional kinematic analysis can provide quantitative assessment of unimanual and bimanual movements. Objective. To assess the natural evolution of reaching kinematics during standard poststroke rehabilitation, focusing on bimanual coordination. Methods. A total of 12 hemiparetic, moderately impaired patients were included within 30 days after a first unilateral ischemic/hemorrhagic stroke; 7 kinematic assessments were performed once a week for 6 weeks and at 3 months after inclusion. The reach-to-grasp task was performed in 3 different conditions: unimanual with the healthy limb (UN), unimanual with the paretic limb (UP), and bimanual (BN/BP). Results. For the paretic limb, movement fluency (number of movement units and total movement time) was lower for bimanual reaching compared with unimanual reaching. For bimanual reaching, (1) movement kinematics were similar for both limbs, (2) recovery patterns of both limbs followed a similar profile with a plateau phase at 6 weeks poststroke, and (3) intertrial variability of between-hands synchronization decreased over sessions, although the mean delays remained the same. Conclusions. Bimanual coordination started to become efficient 6 weeks after onset of stroke, so for patients such as those we tested, this time could be most opportune to start bimanual-oriented rehabilitation. The challenge in future research includes determining the characteristics of patients who may best benefit from bimanual therapy.

Emerging Perspectives in Stroke Rehabilitation

Poststroke characteristics vary significantly between patients and over time, necessitating the introduction of individualized therapy. To provide the appropriate therapy to a patient at the correct time, several theoretical considerations must be taken into account—from a clear delineation of rehabilitation goals to an understanding of how a certain therapy can influence the underlying neuroplasticity. With regard to the differences between upper and lower limb motor recovery, both domains have experienced a change in perspective on rehabilitation. In gait training, assist-as-needed rehabilitation paradigms have become more pertinent, allowing each patient to find his/her individual walking rhythm and style within healthy boundaries. With the introduction of robotics in upper limb training (with or without virtual reality games that are attached), the amount of training and feedback that is provided to a patient can be increased without a rise in cost. The emerging consensus is to consider the various motor therapies and pharmacological interventions as part of a single, large toolbox instead of separate entities, guiding us toward a more patient-therapist-tailored approach, which is demonstrating tremendous efficacy.