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Model-based variables for the kinematic assessment of upper-extremity impairments in post-stroke patients

View Article: PubMed Central - PubMed

ABSTRACT

Background: Common scales for clinical evaluation of post-stroke upper-limb motor recovery are often complemented with kinematic parameters extracted from movement trajectories. However, there is no a general consensus on which parameters to use. Moreover, the selected variables may be redundant and highly correlated or, conversely, may incompletely sample the kinematic information from the trajectories. Here we sought to identify a set of clinically useful variables for an exhaustive but yet economical kinematic characterization of upper limb movements performed by post-stroke hemiparetic subjects.

Methods: For this purpose, we pursued a top-down model-driven approach, seeking which kinematic parameters were pivotal for a computational model to generate trajectories of point-to-point planar movements similar to those made by post-stroke subjects at different levels of impairment.

Results: The set of kinematic variables used in the model allowed for the generation of trajectories significantly similar to those of either sub-acute or chronic post-stroke patients at different time points during the therapy. Simulated trajectories also correctly reproduced many kinematic features of real movements, as assessed by an extensive set of kinematic metrics computed on both real and simulated curves. When inspected for redundancy, we found that variations in the variables used in the model were explained by three different underlying and unobserved factors related to movement efficiency, speed, and accuracy, possibly revealing different working mechanisms of recovery.

Conclusion: This study identified a set of measures capable of extensively characterizing the kinematics of upper limb movements performed by post-stroke subjects and of tracking changes of different motor improvement aspects throughout the rehabilitation process.

Electronic supplementary material: The online version of this article (doi:10.1186/s12984-016-0187-9) contains supplementary material, which is available to authorized users.

No MeSH data available.


Clinical scores and movement characterization. a Mean and standard deviation of clinical scores (FMA, MAS shoulder and MAS elbow, and MI) for T0 and T1 (dark and light colors bars, respectively) for sub-acute and chronic patients (red and blue bars, respectively). Correlation matrix among clinical scales is also reported. b For the Model-based parameters, the average ± standard error (shaded area) time course of recovery for sub-acute (red line) and chronic patients (blue line) is reported. In the bar plots mean values (over repetitions, movement directions, and subjects) for T0 (dark colors) and T1 (light colors) for sub-acute (red bars) and chronic (blue bars) patients and for healthy subjects (yellow bars). Standard error is calculated over subjects. Asterisks (*) indicate significant differences (Wilcoxon signed-rank test, p < 0.05) between T0 and T1 for sub-acute (red), chronic (blue). Yellow and orange asterisks (*) refer to significant differences (Mann–Whitney U-test, p < 0.05) between post-stroke and healthy subjects for only T0 and for T0 and T1, respectively
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Fig4: Clinical scores and movement characterization. a Mean and standard deviation of clinical scores (FMA, MAS shoulder and MAS elbow, and MI) for T0 and T1 (dark and light colors bars, respectively) for sub-acute and chronic patients (red and blue bars, respectively). Correlation matrix among clinical scales is also reported. b For the Model-based parameters, the average ± standard error (shaded area) time course of recovery for sub-acute (red line) and chronic patients (blue line) is reported. In the bar plots mean values (over repetitions, movement directions, and subjects) for T0 (dark colors) and T1 (light colors) for sub-acute (red bars) and chronic (blue bars) patients and for healthy subjects (yellow bars). Standard error is calculated over subjects. Asterisks (*) indicate significant differences (Wilcoxon signed-rank test, p < 0.05) between T0 and T1 for sub-acute (red), chronic (blue). Yellow and orange asterisks (*) refer to significant differences (Mann–Whitney U-test, p < 0.05) between post-stroke and healthy subjects for only T0 and for T0 and T1, respectively

Mentions: Although measuring motor improvements by means of clinical scales was not one of the main aims of this study we reported the scores of both sub-acute and chronic patients after therapy for the purpose of observing parallel significant improvements in both clinical scales and kinematic measures from point-to-point upper limb movements (Fig. 4a). The clinical scores partially correlated. In particular MAS score for the shoulder and the elbow correlated significantly (r = 0.85, p < 0.001), as well as FMA score and Motricity index (r = 0.88, p < 0.001). Moderate correlation between the ability to perform isolated joint movements (FMA score) and upper-limb strength (Motricity index) and, in contrast, low correlation with MAS score (r = 0.14, p >0.05), were in agreement with previous work [6, 32].Fig. 4


Model-based variables for the kinematic assessment of upper-extremity impairments in post-stroke patients
Clinical scores and movement characterization. a Mean and standard deviation of clinical scores (FMA, MAS shoulder and MAS elbow, and MI) for T0 and T1 (dark and light colors bars, respectively) for sub-acute and chronic patients (red and blue bars, respectively). Correlation matrix among clinical scales is also reported. b For the Model-based parameters, the average ± standard error (shaded area) time course of recovery for sub-acute (red line) and chronic patients (blue line) is reported. In the bar plots mean values (over repetitions, movement directions, and subjects) for T0 (dark colors) and T1 (light colors) for sub-acute (red bars) and chronic (blue bars) patients and for healthy subjects (yellow bars). Standard error is calculated over subjects. Asterisks (*) indicate significant differences (Wilcoxon signed-rank test, p < 0.05) between T0 and T1 for sub-acute (red), chronic (blue). Yellow and orange asterisks (*) refer to significant differences (Mann–Whitney U-test, p < 0.05) between post-stroke and healthy subjects for only T0 and for T0 and T1, respectively
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5016877&req=5

Fig4: Clinical scores and movement characterization. a Mean and standard deviation of clinical scores (FMA, MAS shoulder and MAS elbow, and MI) for T0 and T1 (dark and light colors bars, respectively) for sub-acute and chronic patients (red and blue bars, respectively). Correlation matrix among clinical scales is also reported. b For the Model-based parameters, the average ± standard error (shaded area) time course of recovery for sub-acute (red line) and chronic patients (blue line) is reported. In the bar plots mean values (over repetitions, movement directions, and subjects) for T0 (dark colors) and T1 (light colors) for sub-acute (red bars) and chronic (blue bars) patients and for healthy subjects (yellow bars). Standard error is calculated over subjects. Asterisks (*) indicate significant differences (Wilcoxon signed-rank test, p < 0.05) between T0 and T1 for sub-acute (red), chronic (blue). Yellow and orange asterisks (*) refer to significant differences (Mann–Whitney U-test, p < 0.05) between post-stroke and healthy subjects for only T0 and for T0 and T1, respectively
Mentions: Although measuring motor improvements by means of clinical scales was not one of the main aims of this study we reported the scores of both sub-acute and chronic patients after therapy for the purpose of observing parallel significant improvements in both clinical scales and kinematic measures from point-to-point upper limb movements (Fig. 4a). The clinical scores partially correlated. In particular MAS score for the shoulder and the elbow correlated significantly (r = 0.85, p < 0.001), as well as FMA score and Motricity index (r = 0.88, p < 0.001). Moderate correlation between the ability to perform isolated joint movements (FMA score) and upper-limb strength (Motricity index) and, in contrast, low correlation with MAS score (r = 0.14, p >0.05), were in agreement with previous work [6, 32].Fig. 4

View Article: PubMed Central - PubMed

ABSTRACT

Background: Common scales for clinical evaluation of post-stroke upper-limb motor recovery are often complemented with kinematic parameters extracted from movement trajectories. However, there is no a general consensus on which parameters to use. Moreover, the selected variables may be redundant and highly correlated or, conversely, may incompletely sample the kinematic information from the trajectories. Here we sought to identify a set of clinically useful variables for an exhaustive but yet economical kinematic characterization of upper limb movements performed by post-stroke hemiparetic subjects.

Methods: For this purpose, we pursued a top-down model-driven approach, seeking which kinematic parameters were pivotal for a computational model to generate trajectories of point-to-point planar movements similar to those made by post-stroke subjects at different levels of impairment.

Results: The set of kinematic variables used in the model allowed for the generation of trajectories significantly similar to those of either sub-acute or chronic post-stroke patients at different time points during the therapy. Simulated trajectories also correctly reproduced many kinematic features of real movements, as assessed by an extensive set of kinematic metrics computed on both real and simulated curves. When inspected for redundancy, we found that variations in the variables used in the model were explained by three different underlying and unobserved factors related to movement efficiency, speed, and accuracy, possibly revealing different working mechanisms of recovery.

Conclusion: This study identified a set of measures capable of extensively characterizing the kinematics of upper limb movements performed by post-stroke subjects and of tracking changes of different motor improvement aspects throughout the rehabilitation process.

Electronic supplementary material: The online version of this article (doi:10.1186/s12984-016-0187-9) contains supplementary material, which is available to authorized users.

No MeSH data available.