Quantitative measures of fine motor, limb, and postural bradykinesia in very early stage, untreated Parkinson's disease

Few studies have characterized the motor control abnormalities of very early stage Parkinson's disease (PD), when symptoms are mild and usually unilateral. However, this group is the most targeted for potential disease-modifying therapeutics. We have validated several quantitative measures of bradykinesia with the Unified Parkinson's Disease Rating Scale motor disability score (UPDRS III) and have found these useful in studies of advanced PD. In this study, we asked if quantitative measures of finger, forearm, and postural movement velocity could detect bradykinesia in 20 patients with very early stage, untreated PD. The results revealed evidence of significant finger and forearm bradykinesia of the patient group's more affected side when compared to the nondominant side of 19 age-matched control subjects (P = 0.001 and P < 0.001, respectively). Furthermore, the patient group's forearm movement velocity on the more affected side was significantly slower than their less affected side (P = 0.005), highlighting the importance of using an outcome measure that is lateralized in studies of very early stage PD. In contrast to our previous study that revealed significant postural bradykinesia in patients with advanced PD, we did not detect postural bradykinesia in patients with very early stage, untreated PD. Based on these findings, we suggest that the use of quantitative, lateralized measures of bradykinesia would be useful in studies of very early stage, untreated PD. These measures may improve a study by: increasing efficiency and objectivity of the evaluation, decreasing cost, and decreasing the number of subjects needed for statistical significance. (C) 2008 Movement Disorder Society.