Paretic versus non-paretic stepping responses following pelvis perturbations in walking chronic-stage stroke survivors

Journal of NeuroEngineering and Rehabilitation, Oct 2017

The effects of a stroke, such as hemiparesis, can severely hamper the ability to walk and to maintain balance during gait. Providing support to stroke survivors through a robotic exoskeleton, either to provide training or daily-life support, requires an understanding of the balance impairments that result from a stroke. Here, we investigate the differences between the paretic and non-paretic leg in making recovery steps to restore balance following a disturbance during walking. We perturbed 10 chronic-stage stroke survivors during walking using mediolateral perturbations of various amplitudes. Kinematic data as well as gluteus medius muscle activity levels during the first recovery step were recorded and analyzed. The results show that this group of subjects is able to modulate foot placement in response to the perturbations regardless of the leg being paretic or not. Modulation in gluteus medius activity with the various perturbations is in line with this observation. In general, the foot of the paretic leg was laterally placed further away from the center of mass than that of the non-paretic leg, while subjects spent more time standing on the non-paretic leg. The findings suggest that, though stroke-related gait characteristics are present, the modulation with the various perturbations remains unaffected. This might be because all subjects were only mildly impaired, or because these stepping responses partly occur through involuntary pathways which remain unaffected by the complications after the stroke.

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Paretic versus non-paretic stepping responses following pelvis perturbations in walking chronic-stage stroke survivors

Haarman et al. Journal of NeuroEngineering and Rehabilitation Paretic versus non-paretic stepping responses following pelvis perturbations in walking chronic-stage stroke survivors Juliet A. M. Haarman 0 2 Mark Vlutters 0 1 Richelle A. C. M. Olde Keizer 2 Edwin H. F. van Asseldonk 1 Jaap H. Buurke 2 Jasper Reenalda 2 Johan S. Rietman 1 2 Herman van der Kooij 1 0 Equal contributors 1 Department of Biomechanical Engineering, University of Twente , Horstring W119, PO Box 217, 7500 AE Enschede , The Netherlands 2 Roessingh Research and Development , Enschede , The Netherlands Background: The effects of a stroke, such as hemiparesis, can severely hamper the ability to walk and to maintain balance during gait. Providing support to stroke survivors through a robotic exoskeleton, either to provide training or daily-life support, requires an understanding of the balance impairments that result from a stroke. Here, we investigate the differences between the paretic and non-paretic leg in making recovery steps to restore balance following a disturbance during walking. Methods: We perturbed 10 chronic-stage stroke survivors during walking using mediolateral perturbations of various amplitudes. Kinematic data as well as gluteus medius muscle activity levels during the first recovery step were recorded and analyzed. Results: The results show that this group of subjects is able to modulate foot placement in response to the perturbations regardless of the leg being paretic or not. Modulation in gluteus medius activity with the various perturbations is in line with this observation. In general, the foot of the paretic leg was laterally placed further away from the center of mass than that of the non-paretic leg, while subjects spent more time standing on the non-paretic leg. Conclusions: The findings suggest that, though stroke-related gait characteristics are present, the modulation with the various perturbations remains unaffected. This might be because all subjects were only mildly impaired, or because these stepping responses partly occur through involuntary pathways which remain unaffected by the complications after the stroke. Stroke; Balance during gait; Perturbed walking; Reactive foot placement; Muscle activity changes Background Stroke survivors often experience problems with maintaining their balance. A variety of neurological deficits can hamper balance control during walking, such as hemiparesis, sensory impairments, as well as cognitive problems such as fear of falling. As a consequence, fall rates in stroke survivors are 2–8 times higher than those in healthy, age-matched subjects [ 1 ]. In general, especially balance control in the frontal plane is often considered challenging, requiring adequate foot placement to continue walking [ 2 ]. This might be an additional challenge when suffering from hemiparesis following a stroke, which could lead to differences in recovery steps made with the paretic and the non-paretic leg in response to a disturbance during walking. To reduce the fall risk of stroke survivors and make their rehabilitation more effective, it is required to characterize how balance control is affected by a stroke. Such knowledge might be used to provide limb-specific support in robot-assisted gait rehabilitation. Stroke survivors typically show differences in gait characteristics between the paretic and non-paretic leg during unperturbed walking, for example as a result of decreased motor control in the paretic leg. In a study by Balasubramanian et al. subjects placed the paretic leg at an increased lateral distance from the pelvis compared to the non-paretic leg in mediolateral (ML) foot placement during unperturbed walking [ 3 ]. However, no differences in step width were found with regard to the leg used for stepping. It is therefore of importance to consider both legs individually, in a body referenced frame such as that of the center of mass (COM). Dean et al. studied the relation between gluteus medius muscle activity in the swing leg and both the ML position and velocity of the COM relative to the stance foot [ 4 ]. For low fall-risk subjects the results suggest a stronger activity modulation in the non-paretic swing leg than in the paretic swing leg, though it did not show how both legs respond to actual destabilizing conditions such as external perturbations. Perturbations can be used to affect the body state, such as the position and velocity of the COM relative to the stance foot. This may lead to adjustments in foot placement location and timing to maintain balance. In Krasovsky et al. perturbations were applied by unexpectedly arresting the ankle of the leg at early swing [ 5 ]. Stroke survivors showed shorter step lengths and shorter swing times compared to healthy controls when stepping in response to perturbations applied to the non-paretic swing leg. Furthermore, in Hak et al. continuous ML support surface translations were used to assess if and how low-fall ri (...truncated)


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Juliet A. M. Haarman, Mark Vlutters, Richelle A. C. M. Olde Keizer, Edwin H. F. van Asseldonk, Jaap H. Buurke, Jasper Reenalda, Johan S. Rietman, Herman van der Kooij. Paretic versus non-paretic stepping responses following pelvis perturbations in walking chronic-stage stroke survivors, Journal of NeuroEngineering and Rehabilitation, 2017, pp. 106, DOI: 10.1186/s12984-017-0317-z