Movement quality of repetitive self-paced single joint rapid arm movements on Parkinson's disease: acute effect of 1-dopa

Most studies on single-joint ballistic movements in PD have reported smaller differences between ON and OFF states than those exhibited when PD patients are compared with normal controls. We developed a mathematical model (quality of movement coefficient, QMC), which represents a combination of the diverse kinematic variables applicable to repetitive ballistic movements and depicting the differences between normal subjects and PD patients as well as disclosing changes induced by 1-dopa. Seven patients were evaluated in ON and OFF states. An optoelectronic system (SELSPOT II) was used to digitize movement trajectories. Patients were instructed to repetitively flex and extend the forearms maximizing speed during 20 s. Seven normal controls were also evaluated. Significant differences were found in the QMC between ON and OFF states (ANOVA p < 0.0 1) and between patients and normal controls (ANOVA p < 0.04). Moreover, QMC significantly correlated with UPDRS motor score in both ON and OFF states [ R2 F(1,5) = 12.06; p < 0.01]. In conclusion, we found that QMC seems to be a sensitive indicator of Parkinsonian disabilities as well as of 1-dopa effect