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Soleus H-reflex recruitment is not altered in persons with chronic spinal cord injury
Sheila M Schindler-Ivens1, Richard K Shields
1Graduate Program in Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, IA, USA. s-schindler-ivens@northwestern.edu
Objective:
To determine whether spasticity in persons with spinal cord injury (SCI) is associated with elevated monosynaptic reflex excitability.
Design:
One-way experimental.
Setting:
Research laboratory.
Participants:
Convenience sample of 9 subjects (8 men, 1 woman) with chronic and complete SCI and 20 persons (14 men, 6 women) with no neurologic impairment. Subjects with SCI exhibited lower-extremity spasticity as indicated by velocity-dependent increased resistance to passive muscle stretch, abnormally brisk deep tendon reflexes, involuntary lower-extremity flexion and/or extension spasms, and clonus.
Intervention:
Soleus H-reflex recruitment curves were elicited in all subjects.
Main Outcome Measures:
Soleus H-reflex threshold (HTH), gain (HGN), and amplitude (HPP).
Results:
There was no difference between subjects with and without SCI in HTH, HGN, or HPP.
Conclusions:
Spasticity in people with chronic and complete SCI was not associated with increased excitability of the connections between Ia afferent projections and motoneurons. Factors extrinsic to these connections may have a role in spasticity caused by SCI.
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