Related Experiment Video
Updated: Dec 14, 2025
Isokinetic Robotic Device to Improve Test-Retest and Inter-Rater Reliability for Stretch Reflex Measurements in Stroke Patients with Spasticity
Published on: June 12, 2019
Deficits in corticospinal control of stretch reflex thresholds in stroke: Implications for motor impairment
Daniele Piscitelli1, Nicolas A Turpin2, Sandeep K Subramanian3
1School of Physical and Occupational Therapy, McGill University, Canada; Jewish Rehabilitation Hospital Site, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Canada.
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.
