Quantification of Clinical Assessment of Parkinsonian Rigidity

This study aims to analyze viscoelastic properties of the wrist in patients with Parkinson’s disease (PD). Patients with PD were recruited from outpatient clinic. Intermittent passive movement of the wrist was imposed and resistive torque and joint angle were measured. Using the experimental data, viscoelastic constants of the wrist were calculated from the least square method. Viscoelastic constants significantly correlated with the rigidity score of the Unified Parkinson’s disease Rating Scale (UPDRS) (p<0.01). Moreover, damping constant was different in all pairs of rigidity scores and spring constant was different in most pairs of rigidity scores (post-hoc test, p<0.01). These results suggest that viscoelastic properties can be used as quantitative measures of parkinsonian rigidity.