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Modulation of soleus stretch reflexes during walking in people with chronic incomplete spinal cord injury.

Abstract

In people with spasticity due to chronic incomplete spinal cord injury (SCI), it has been presumed that the abnormal stretch reflex activity impairs gait. However, locomotor stretch reflexes across all phases of walking have not been investigated in people with SCI. Thus, to understand modulation of stretch reflex excitability during spastic gait, we investigated soleus stretch reflexes across the entire gait cycle in nine neurologically normal participants and nine participants with spasticity due to chronic incomplete SCI (2.5-11 year post-injury). While the participant walked on the treadmill at his/her preferred speed, unexpected ankle dorsiflexion perturbations (6° at 250°/s) were imposed every 4-6 steps. The soleus H-reflex was also examined. In participants without SCI, spinal short-latency "M1", spinal medium latency "M2", and long-latency "M3" were clearly modulated throughout the step cycle; the responses were largest in the mid-stance and almost completely suppressed during the stance-swing transition and swing phases. In participants with SCI, M1 and M2 were abnormally large in the mid-late-swing phase, while M3 modulation was similar to that in participants without SCI. The H-reflex was also large in the mid-late-swing phase. Elicitation of H-reflex and stretch reflexes in the late swing often triggered clonus and affected the soleus activity in the following stance. In individuals without SCI, moderate positive correlation was found between H-reflex and stretch reflex sizes across the step cycle, whereas in participants with SCI, such correlation was weak to non-existing, suggesting that H-reflex investigation would not substitute for stretch reflex investigation in individuals after SCI.

Authors+Show Affiliations

College of Health Professions, Medical University of South Carolina, 77 President Street, MSC700, Charleston, SC, 29425, USA. thompsai@musc.edu.Center for Sensory-Motor Interaction, Aalborg University, 9220, Aalborg, Denmark.Center for Sensory-Motor Interaction, Aalborg University, 9220, Aalborg, Denmark. Lundbeck Foundation, Scherfigsvej 7, 2100, Copenhagen, Denmark.Center for Sensory-Motor Interaction, Aalborg University, 9220, Aalborg, Denmark.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31309252

Citation

Thompson, Aiko K., et al. "Modulation of Soleus Stretch Reflexes During Walking in People With Chronic Incomplete Spinal Cord Injury." Experimental Brain Research, 2019.
Thompson AK, Mrachacz-Kersting N, Sinkjær T, et al. Modulation of soleus stretch reflexes during walking in people with chronic incomplete spinal cord injury. Exp Brain Res. 2019.
Thompson, A. K., Mrachacz-Kersting, N., Sinkjær, T., & Andersen, J. B. (2019). Modulation of soleus stretch reflexes during walking in people with chronic incomplete spinal cord injury. Experimental Brain Research, doi:10.1007/s00221-019-05603-1.
Thompson AK, et al. Modulation of Soleus Stretch Reflexes During Walking in People With Chronic Incomplete Spinal Cord Injury. Exp Brain Res. 2019 Jul 15; PubMed PMID: 31309252.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Modulation of soleus stretch reflexes during walking in people with chronic incomplete spinal cord injury. AU - Thompson,Aiko K, AU - Mrachacz-Kersting,N, AU - Sinkjær,T, AU - Andersen,J B, Y1 - 2019/07/15/ PY - 2019/04/05/received PY - 2019/07/08/accepted PY - 2019/7/17/entrez KW - Chronic incomplete spinal cord injury KW - Hyperreflexia KW - Locomotion KW - Spasticity JF - Experimental brain research JO - Exp Brain Res N2 - In people with spasticity due to chronic incomplete spinal cord injury (SCI), it has been presumed that the abnormal stretch reflex activity impairs gait. However, locomotor stretch reflexes across all phases of walking have not been investigated in people with SCI. Thus, to understand modulation of stretch reflex excitability during spastic gait, we investigated soleus stretch reflexes across the entire gait cycle in nine neurologically normal participants and nine participants with spasticity due to chronic incomplete SCI (2.5-11 year post-injury). While the participant walked on the treadmill at his/her preferred speed, unexpected ankle dorsiflexion perturbations (6° at 250°/s) were imposed every 4-6 steps. The soleus H-reflex was also examined. In participants without SCI, spinal short-latency "M1", spinal medium latency "M2", and long-latency "M3" were clearly modulated throughout the step cycle; the responses were largest in the mid-stance and almost completely suppressed during the stance-swing transition and swing phases. In participants with SCI, M1 and M2 were abnormally large in the mid-late-swing phase, while M3 modulation was similar to that in participants without SCI. The H-reflex was also large in the mid-late-swing phase. Elicitation of H-reflex and stretch reflexes in the late swing often triggered clonus and affected the soleus activity in the following stance. In individuals without SCI, moderate positive correlation was found between H-reflex and stretch reflex sizes across the step cycle, whereas in participants with SCI, such correlation was weak to non-existing, suggesting that H-reflex investigation would not substitute for stretch reflex investigation in individuals after SCI. SN - 1432-1106 UR - https://www.unboundmedicine.com/medline/citation/31309252/Modulation_of_soleus_stretch_reflexes_during_walking_in_people_with_chronic_incomplete_spinal_cord_injury L2 - https://dx.doi.org/10.1007/s00221-019-05603-1 DB - PRIME DP - Unbound Medicine ER -