May 2010

Higher Muscle Passive Stiffness in Parkinson’s Disease Patients Than in Controls Measured by Myotonometry

Authors: J. Marusiak, K. Kisiel-Sajewicz, A. Jaskólska, A. Jaskólski

Affiliations: Department of Kinesiology, Faculty of Physiotherapy, University School of Physical Education, Wroclaw, Poland

Journal: Archives of Physical Medicine and Rehabilitation - February 2011, Volume 26, Issue 2, Pages 213–217 (DOI: 10.1016/j.apmr.2010.01.012)

To assess muscle passive stiffness in medicated Parkinson’s disease patients using myotonometry.

Case-control study.

Kinesiology laboratory.

Women with Parkinson’s disease (PD) (n=8) and healthy matched elderly women (controls) (n=10) (mean age: PD, 77±3y; controls, 77±4y).

Not applicable.

Main Outcome Measures
Passive stiffness of relaxed biceps brachii (BB) muscle was measured using myotonometry. Additionally, surface electromyographic and mechanomyographic signals were recorded from the muscle at rest, and amplitude of those signals was analyzed offline.

The values of BB muscle passive stiffness were significantly (P=.004) higher in PD than in the controls, with a statistically significant influence of parkinsonian rigidity score (Unified Parkinson’s Disease Rating Scale) on intergroup differences (P<.001). The Spearman correlation coefficient ρ value showed a significant (P=.005) positive relationship (ρ=.866) between the parkinsonian rigidity score and passive stiffness values of BB in PD. The groups did not differ significantly in the electromyogram amplitude (P=.631) and mechanomyogram amplitude (P=.593) of the BB muscle, and values of these parameters did not correlate significantly with rigidity score (P=.555, P=.745, respectively) in the patients.

Myotonometer is a sensitive enough tool to show that PD patients have higher muscle passive stiffness than healthy controls.