Direction-Specific Instability Poststroke Is Associated With Deficient Motor Modules for Balance Control

Useless crap. Nothing here will help survivors recover.  Yes, most strokes have postural instability but what the hell is the protocol to address that? All these Ph.Ds and we still get useless crapola like this. Have none of them ever talked to a survivor about their needs?
http://journals.sagepub.com/doi/abs/10.1177/1545968318783884

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Digna de Kam, PhD¹²

Digna de Kam

1Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands2University of Pittsburgh, Swanson School of Engineering, Department of Bioengineering, Pittsburgh, PA, United States
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, Alexander C. Geurts, PhD¹³

Alexander C. Geurts

1Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands3Sint Maartenskliniek Research, Nijmegen, The Netherlands
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, Vivian Weerdesteyn, PhD¹³

Vivian Weerdesteyn

1Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands3Sint Maartenskliniek Research, Nijmegen, The Netherlands
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Gelsy Torres-Oviedo, PhD²

Gelsy Torres-Oviedo

2University of Pittsburgh, Swanson School of Engineering, Department of Bioengineering, Pittsburgh, PA, United States
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, Digna de Kam, PhD¹²

Digna de Kam

1Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands2University of Pittsburgh, Swanson School of Engineering, Department of Bioengineering, Pittsburgh, PA, United States
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, Alexander C. Geurts, PhD¹³

Alexander C. Geurts

1Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands3Sint Maartenskliniek Research, Nijmegen, The Netherlands
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, Vivian Weerdesteyn, PhD¹³

Vivian Weerdesteyn

1Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands3Sint Maartenskliniek Research, Nijmegen, The Netherlands
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, Gelsy Torres-Oviedo, PhD²

Gelsy Torres-Oviedo

2University of Pittsburgh, Swanson School of Engineering, Department of Bioengineering, Pittsburgh, PA, United States
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First Published June 29, 2018 Research Article

https://doi.org/10.1177/1545968318783884

Article information

Article Information

Article first published online: June 29, 2018

https://doi.org/10.1177/1545968318783884

Digna de Kam, PhD^{1, 2}, Alexander C. Geurts, PhD^{1, 3}, Vivian Weerdesteyn, PhD^{1, 3}, Gelsy Torres-Oviedo, PhD²

¹Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands

²University of Pittsburgh, Swanson School of Engineering, Department of Bioengineering, Pittsburgh, PA, United States

³Sint Maartenskliniek Research, Nijmegen, The Netherlands

Corresponding Author: Gelsy Torres-Oviedo, PhD, Department of Bioengineering, University of Pittsburgh, 4420 Bayard St, Suite 110, Pittsburgh, PA 15213, USA. Email: gelsyto@pitt.edu

• Abstract

Abstract

Defective muscle coordination for balance recovery may contribute to stroke survivors’ propensity for falling. Thus, we investigated deficits in muscle coordination for postural control and their association to body sway following balance perturbations in people with stroke. Specifically, we compared the automatic postural responses of 8 leg and trunk muscles recorded bilaterally in unimpaired individuals and those with mild to moderate impairments after unilateral supratentorial lesions (>6 months). These responses were elicited by unexpected floor translations in 12 directions. We extracted motor modules (ie, muscle synergies) for each leg using nonnegative matrix factorization. We also determined the magnitude of perturbation-induced body sway using a single-link inverted pendulum model. Whereas the number of motor modules for balance was not affected by stroke, those formed by muscles with long latency responses were replaced by atypically structured paretic motor modules (atypical muscle groupings), which hints at direct cerebral involvement in long-latency feedback responses. Other paretic motor modules had intact structure but were poorly recruited, which is indicative of indirect cerebral control of balance. Importantly, these paretic deficits were strongly associated with postural instability in the preferred activation direction of the impaired motor modules. Finally, these deficiencies were heterogeneously distributed across stroke survivors with lesions in distinct locations, suggesting that different cerebral substrates may contribute to balance control. In conclusion, muscle coordination deficits in the paretic limb of stroke survivors result in direction-specific postural instability, which highlights the importance of targeted interventions to address patient-specific balance impairments.