Article

This position paper introduces an assessment method using staged calculation of
coefficients of impairment in spastic paresis, with its rationale and proposed
use. The syndrome of deforming spastic paresis superimposes two disorders around
each joint: a neural disorder comprising stretch-sensitive paresis in agonists
and antagonist muscle overactivity, and a muscle disorder ("spastic myopathy")
combining shortening and loss of extensibility in antagonists. Antagonist muscle
overactivity includes spastic cocontraction (misdirected descending command),
spastic dystonia (tonic involuntary muscle activation, at rest) and spasticity
(increased velocity-dependent reflexes to phasic stretch, at rest). This
understanding of various types of antagonist resistance as the key limiting
factors in paretic movements prompts a stepwise, quantified, clinical assessment
of antagonist resistances, elaborating on the previously developed Tardieu Scale.
Step 1 quantifies limb function (e.g. ambulation speed in lower limb, Modified
Frenchay Scale in upper limb). The following four steps evaluate various angles X
of antagonist resistance, in degrees all measured from 0 degrees , position of
minimal stretch of the tested antagonist. Step 2 rates the functional muscle
length, termed XV1 (V1, slowest stretch velocity possible), evaluated as the
angle of arrest upon slow and strong passive muscle stretch. XV1 is appreciated
with respect to the expected normal passive amplitude, XN, and reflects combined
muscle contracture and residual spastic dystonia. Step 3 determines the angle of
catch upon fast stretch, termed XV3 (V3, fastest stretch velocity possible),
reflecting spasticity. Step 4 measures the maximal active range of motion against
the antagonist, termed XA, reflecting agonist capacity to overcome passive
(stiffness) and active (spastic cocontraction) antagonist resistances over a
single movement. Finally, Step 5 rates the residual active amplitude after
15seconds of maximal amplitude rapid alternating movements, XA15. Amplitude
decrement from XA to XA15 reflects fatigability. Coefficients of shortening
(XN-XV1)/XN, spasticity (XV1-XV3)/XV1, weakness (XV1-XA)/XV1 and fatigability
(XA-XA15)/XA are derived. A high (e.g., >10%) coefficient of shortening prompts
aggressive treatment of the muscle disorder - e.g. by stretch programs, such as
prolonged stretch postures -, while high coefficients of weakness or fatigability
prompt addressing the neural motor command disorder, e.g. using training programs
such as repeated alternating movements of maximal amplitude.
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Langue : ANGLAIS