Article

There is no easy and reliable method to measure spasticity, although
it is a common and important symptom after a brain injury. The aim of
this study was to develop and validate a new method to measure spasticity that
can be easily used in clinical practice. METHODS: A biomechanical model was
created to estimate the components of the force resisting passive hand extension,
namely (a) inertia (IC), (b) elasticity (EC), (c) viscosity (VC), and (d) neural
components (NC). The model was validated in chronic stroke patients with varying
degree of hand spasticity. Electromyography (EMG) was recorded to measure the
muscle activity induced by the passive stretch. RESULTS: The model was validated
in 3 ways: (a) NC was reduced after an ischemic nerve block, (b) NC correlated
with the integrated EMG across subjects and in the same subject during the
ischemic nerve block, and (c) NC was velocity dependent. In addition, the total
resisting force and NC correlated with the modified Ashworth score. According to
the model, the neural and nonneural components varied between patients. In most
of the patients, but not in all, the NC dominated. CONCLUSIONS: The results
suggest that the model allows valid measurement of spasticity in the upper
extremity of chronic stroke patients and that it can be used to separate the
neural component induced by the stretch reflex from resistance caused by altered
muscle properties.

Langue : ANGLAIS