Dopaminergic modulation of multi-muscle synergies in postural tasks performed by patients with Parkinson’s disease

• Published in: Journal of electromyography and kinesiology 2017-04, Vol.33, p.20-26
• Main Authors: Falaki, Ali, Huang, Xuemei, Lewis, Mechelle M, Latash, Mark L
• Format: Article
• Language: English
• Subjects: Adult; Aged; Anticipatory synergy adjustments; Dopamine Agents - pharmacology; Dopamine Agents - therapeutic use; Dopaminergic medication; Female; Humans; Levodopa - pharmacology; Levodopa - therapeutic use; Male; Muscle Contraction; Muscle mode; Muscle, Skeletal - physiology; Parkinson Disease - drug therapy; Parkinson Disease - physiopathology; Parkinson’s disease; Physical Medicine and Rehabilitation; Postural Balance - drug effects; Posture; Synergy
• ISSN: 1050-6411; 1873-5711
• DOI: 10.1016/j.jelekin.2017.01.002

Abstract Background Postural instability is one of most disabling motor symptoms in Parkinson’s disease. Indices of multi-muscle synergies are new measurements of postural stability. Objectives We explored the effects of dopamine-replacement drugs on multi-muscle synergies stabilizing center of pressure coordinate and their adjustments prior to a self-triggered perturbation in patients with Parkinson’s disease. We hypothesized that both synergy indices and synergy adjustments would be improved on dopaminergic drugs. Methods Patients at Hoehn-Yahr stages II and III performed whole-body tasks both off- and on-drugs while standing. Muscle modes were identified as factors in the muscle activation space. Synergy indices stabilizing center of pressure in the anterior-posterior direction were quantified in the muscle mode space during a load-release task. Results Dopamine-replacement drugs led to more consistent organization of muscles in stable groups (muscle modes). On-drugs patients showed larger indices of synergies and anticipatory synergy adjustments. In contrast, no medication effects were seen on anticipatory postural adjustments or other performance indices. Conclusions Dopamine-replacement drugs lead to significant changes in characteristics of multi-muscle synergies in Parkinson’s disease. Studies of synergies may provide a biomarker sensitive to problems with postural stability and agility and to efficacy of dopamine-replacement therapy.