Faculty Collaboration Database

Contribution of muscle afferents to prolonged flexion withdrawal reflexes in human spinal cord injury. J Neurophysiol 2004 Dec;92(6):3375-84

Date

07/16/2004

Pubmed ID

15254071

DOI

10.1152/jn.00152.2004

Scopus ID

2-s2.0-8644274640 (requires institutional sign-in at Scopus site)   22 Citations

Abstract

The contribution of force-sensitive muscular afferents to prolonged flexion withdrawal reflexes, or flexor spasms, after human spinal cord injury (SCI) was investigated. In three separate experimental conditions, flexion reflexes were triggered in subjects with SCI using trains of electrocutaneous stimuli delivered at the foot and lower leg and compared with reflexes elicited via intramuscular (i.m.) electrical stimuli. In the first experiment, flexion reflexes were elicited using i.m. stimuli to the tibialis anterior (TA) in the majority of subjects tested. The ratio of peak isometric ankle to hip torques during i.m.-triggered reflexes were proportionally similar to those evoked by electrocutaneous foot or shank stimulation, although the latency to onset and peak flexion torques were significantly longer with i.m. stimulation. In the second experiments, the amplitude and frequency of i.m. TA stimulation were varied to alter the stimulus-induced muscle torque. Peak ankle and hip torques generated during the flexion reflex responses were correlated to a greater extent with stimulus-induced muscle torques as compared with the modulated stimulus parameters. In the third experimental series, i.m. stimuli delivered to the gastrocnemius (GS) elicited flexion reflexes in approximately half of the subjects tested. The combined data indicate a potentially prominent role of the stimulus-induced muscle contraction to the magnitude and latency of flexor reflex behaviors after i.m. TA stimulation. Results after i.m. GS stimulation indicate multi-joint flexion reflexes can also be elicited, although to a lesser extent than i.m. TA stimulation.

Author List

Hornby TG, Tysseling-Mattiace VM, Benz EN, Schmit BD

Author

Brian Schmit PhD Professor in the Biomedical Engineering department at Marquette University

MESH terms used to index this publication - Major topics in bold

Adult
Electromyography
Female
Foot
Humans
Male
Middle Aged
Motor Neurons
Muscle Contraction
Muscle, Skeletal
Neurons, Afferent
Reflex
Skin
Spasm
Spinal Cord Injuries
Torque