Article

Postural instability is one of most disabling motor symptoms in
Parkinson's disease. Indices of multi-muscle synergies are new measurements of
movement and postural stability. OBJECTIVES: Multi-muscle synergies stabilizing
vertical posture were studied in Parkinson's disease patients without clinical
symptoms of postural instability (Hoehn-Yahr</=II) and age-matched controls. We
tested the hypothesis that both synergy indices during quiet standing and synergy
adjustments to self-triggered postural perturbations would be reduced in patients. METHODS: Eleven Parkinson's disease patients and 11 controls performed
whole-body tasks while standing. Surface electromyography was used to quantify
synergy indices stabilizing center of pressure shifts in the anterior-posterior
direction during a load-release task. RESULTS: Parkinson's disease patients
showed a significantly lower percentage of variance in the muscle activation
space accounted for by the first four principal components, significantly reduced
synergy indices during steady state, and significantly reduced anticipatory
synergy adjustments (a drop in the synergy index prior to the self-triggered
unloading). CONCLUSIONS: The study demonstrates for the first time that impaired
synergic control in Parkinson's disease can be quantified in postural tasks, even
in patients without clinical manifestations of postural instability. Synergy
measurements may provide a biomarker sensitive for early problems with postural
stability in Parkinson's disease.
CI - Copyright (c) 2015 Elsevier B.V. All rights reserved.

Langue : ANGLAIS