A comprehensive model of spastic hypertonia derived from the pendulum test of the leg

We propose a comprehensive model of spastic hypertonia based on clinical neurophysiology and validated using experimental data obtained from the pendulum test of the leg in 8 healthy volunteers and 15 spastic patients. This nonlinear computational model includes mechanical parameters and a stretch r...

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Bibliographic Details
Published in:Muscle & nerve 2001-12, Vol.24 (12), p.1612-1621
Main Authors: Le Cavorzin, Philippe, Poudens, S. Annick, Chagneau, Francis, Carrault, Guy, Allain, Hervé, Rochcongar, Pierre
Format: Article
Language:English
Subjects:
Adult
Biological and medical sciences
Computer Simulation
Diseases of striated muscles. Neuromuscular diseases
Electromyography
Female
Humans
Leg - physiology
Male
Medical sciences
modeling
Models, Neurological
motor control
Muscle Spasticity - diagnosis
Muscle Spasticity - physiopathology
Neurology
pendulum test
Reflex, Stretch - physiology
Reproducibility of Results
spasticity
stretch reflex
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Summary:We propose a comprehensive model of spastic hypertonia based on clinical neurophysiology and validated using experimental data obtained from the pendulum test of the leg in 8 healthy volunteers and 15 spastic patients. This nonlinear computational model includes mechanical parameters and a stretch reflex representation involving three neural parameters: a threshold coefficient, the gain of the stretch reflex, and a time lag accounting for the reflex loop latency and the electromechanical coupling delay. Variation of the threshold coefficient alone allowed an overall reproduction of experimental data obtained from spastic and healthy subjects. We propose that this parameter could represent the supraspinal drive, supposed to be preserved in control subjects and decreased in spastic patients. No subsequent variation of the reflex gain was required to simulate spastic traces. Adjustment of the time lag influenced the duration of the swinging phase and oscillatory phenomena possibly occurring during the pendulum test. It could be related to the involvement of either short‐ or long‐latency stretch reflex loops. With respect to current neurophysiological concepts of motor control, this modeling approach may help in understanding mechanisms underlying spastic hypertonia, and in predicting the clinical effect of antispasticity agents. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1612–1621, 2001
ISSN:0148-639X
1097-4598
DOI:10.1002/mus.1196