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BioMed Research International
Volume 2015, Article ID 276182, 8 pages
Research Article

Neural and Nonneural Contributions to Wrist Rigidity in Parkinson’s Disease: An Explorative Study Using the NeuroFlexor

1Department of Neuroscience, Rehabilitation Medicine, Uppsala University, 75105 Uppsala, Sweden
2Department of Women’s and Children’s Health, Karolinska Institutet, 17177 Stockholm, Sweden
3Department of Clinical Sciences, Karolinska Institutet, Danderyd University Hospital, 18288 Stockholm, Sweden
4FR3636 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France

Received 8 August 2014; Accepted 17 October 2014

Academic Editor: Alfonso Fasano

Copyright © 2015 H. Zetterberg et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective. The NeuroFlexor is a novel method incorporating a biomechanical model for the measurement of neural and nonneural contributions to resistance induced by passive stretch. In this study, we used the NeuroFlexor method to explore components of passive movement resistance in the wrist and finger muscles in subjects with Parkinson’s disease (PD). Methods. A cross-sectional comparison was performed in twenty-five subjects with PD with clinically identified rigidity and 14 controls. Neural (NC), elastic (EC), and viscous (VC) components of the resistance to passive extension of the wrist were calculated using the NeuroFlexor. Measurements were repeated during a contralateral activation maneuver. Results. PD subjects showed greater total resistance and NC compared to controls. EC and VC did not differ significantly between groups. Contralateral activation maneuver resulted in increased NC in the PD group but this increase was due to increased resting tension. Total resistance and NC correlated with clinical ratings of rigidity and with bradykinesia. Conclusions. The findings suggest that stretch induced reflex activity, but not nonneural resistance, is the major contributor to rigidity in wrist muscles in PD. The NeuroFlexor is a potentially valuable clinical and research tool for quantification of rigidity.