Quantification of rigidity in Parkinson's disease.

In this paper, a new method for quantification of rigidity in elbow joint of Parkinsonian patients is introduced. One of the most known syndromes in Parkinson's disease (PD) is increased passive stiffness in muscles, which leads to rigidity in joints. Clinical evaluation of stiffness in wrist and/or elbow, commonly used by clinicians, is based on Unified Parkinson's Disease Rating System (UPDRS). Subjective nature of this method may influence the accuracy and precision of evaluations. Hence, introducing an objective standard method based on quantitative measurements may be helpful. A test rig was designed and fabricated to measure range of motion and viscous and elastic components of passive stiffness in elbow joint. Measurements were done for 41 patients and 11 controls. Measures were extracted using Matlab-R14 software and statistic analyses were done by Spss-13. Relation between each computed measure and the level of illness were analyzed. Results showed a better correlation between viscous component of stiffness and UPDRS score compared to the elastic component. Results of this research may help to introduce a standard objective method for evaluation of PD.