Affiliation: | aSensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA bDepartment of Physiology, Northwestern University, Chicago, IL 60611, USA cDepartment of Physical Therapy, University of Illinois at Chicago, Chicago, IL 60612, USA dDepartment of Biomedical Engineering, Marquette University, Milwaukee, P.O. Box 1881, Milwaukee, WI 53201-1881, USA |
Abstract: | The current study compared the intralimb coordination of flexor reflex responses in spinal intact and complete chronic spinal cord injured (SCI) individuals. Noxious electrocutaneous stimulation was applied at the apex of the medial arch of the foot (50 mA, 500 Hz, 1 ms pulse width, 20 ms) in 21 complete chronic SCI and 19 spinal intact volunteers and the flexor reflex response was quantified by measuring the isometric joint torques at the ankle, knee and hip. The results showed that SCI individuals had significantly smaller peak knee and hip joint flexion torques, often exhibited a net knee extension torque, and produced a much smaller hip joint flexion torque during the flexor reflex response in contrast to the spinal intact individuals. The latency of the reflex response, measured from the tibialis anterior electromyogram, was comparable in both test populations. These findings indicate that the intralimb coordination of the flexor reflex response of chronic complete SCI individuals is altered, possibly reflecting a functional reorganization of the flexion pathways of the spinal cord. |