Daniele Piscitelli1, Nicolas A Turpin2, Sandeep K Subramanian3, Anatol G Feldman4, Mindy F Levin5. 1. School of Physical and Occupational Therapy, McGill University, Canada; Jewish Rehabilitation Hospital Site, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Canada. 2. Department of Neuroscience, University of Montreal, Canada; Department of Sport Sciences (STAPS), IRISSE lab (EA 4075), University of la Réunion, Tampon, France. 3. Jewish Rehabilitation Hospital Site, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Canada; Department of Neuroscience, University of Montreal, Canada; Department of Physical Therapy, School of Health Professions, UT Health San Antonio, USA. 4. Jewish Rehabilitation Hospital Site, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Canada; Department of Neuroscience, University of Montreal, Canada. 5. School of Physical and Occupational Therapy, McGill University, Canada; Jewish Rehabilitation Hospital Site, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Canada. Electronic address: mindy.levin@mcgill.ca.
Abstract
OBJECTIVES: The corticospinal system (CS) regulates muscle activation through shifts in muscle-level tonic stretch-reflex thresholds (TSRT). This ability is impaired in stroke and contributes to sensorimotor impairments such as spasticity. We determined the role of CS in elbow flexor activity regulation in healthy and post-stroke subjects. We also determined whether CS modulation deficits were related to sensorimotor impairment intensity in post-stroke individuals. METHODS: Seventeen healthy (59.8 ± 12.2 yr) and 27 stroke subjects (58.7 ± 10.1 yr) had transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1) flexor representation to elicit motor-evoked potentials (MEPs) in elbow flexors in different angular positions. In a subset of post-stroke subjects (n = 12), flexor TSRTs were measured in passive and active conditions, and TSRT modulation was determined. RESULTS: Position-related MEP amplitude modulation was similar in healthy and mild stroke subjects, while subjects with more severe stroke exhibited less consistent modulation. MEP modulation in stroke was related to clinical upper limb motor impairment, spasticity, and the ability to modulate TSRTs between passive and active elbow movements. CONCLUSIONS: CS output was closely related to TSRT modulation. Impairments in TSRT regulation may underlie motor deficits in moderate-to-severe post-stroke individuals. SIGNIFICANCE: Translation of these neurophysiological findings to clinical applications may enhance post-stroke motor recovery.
OBJECTIVES: The corticospinal system (CS) regulates muscle activation through shifts in muscle-level tonic stretch-reflex thresholds (TSRT). This ability is impaired in stroke and contributes to sensorimotor impairments such as spasticity. We determined the role of CS in elbow flexor activity regulation in healthy and post-stroke subjects. We also determined whether CS modulation deficits were related to sensorimotor impairment intensity in post-stroke individuals. METHODS: Seventeen healthy (59.8 ± 12.2 yr) and 27 stroke subjects (58.7 ± 10.1 yr) had transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1) flexor representation to elicit motor-evoked potentials (MEPs) in elbow flexors in different angular positions. In a subset of post-stroke subjects (n = 12), flexor TSRTs were measured in passive and active conditions, and TSRT modulation was determined. RESULTS: Position-related MEP amplitude modulation was similar in healthy and mild stroke subjects, while subjects with more severe stroke exhibited less consistent modulation. MEP modulation in stroke was related to clinical upper limb motor impairment, spasticity, and the ability to modulate TSRTs between passive and active elbow movements. CONCLUSIONS:CS output was closely related to TSRT modulation. Impairments in TSRT regulation may underlie motor deficits in moderate-to-severe post-stroke individuals. SIGNIFICANCE: Translation of these neurophysiological findings to clinical applications may enhance post-stroke motor recovery.
Authors: Kaleb Vinehout; Kelsey Tynes; Miguel R Sotelo; Allison S Hyngstrom; John R McGuire; Brian D Schmit Journal: Front Rehabil Sci Date: 2021-12-16
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