BradykAn: A motion capture system for objectification of hand motor tests in Parkinson Disease

We developed a software program, BradykAn, that computes motion characteristics and processes data acquired from compact optical motion capture systems (MoCap) such as Optitrack V120: Trio which provides accurate and easily acquired information about 3-dimensial movement. BradykAn has implemented algorithms and protocols for the evaluation of Unified Parkinson's Disease Rating Scale hand motor tests. The BradykAn was validated on a finger tapping test for patients with Parkinson Disease (PD), where the parameters describing repetitive movement speed, amplitude, and frequency were computed. We examined 55 PD patients (29M,26F), mean age 65 (46-85) years, H&Y stage 2 (1-2.5) and 59 (28M,31F) normal controls, mean age 65 (41-83) years. The analysis delivered significant results in most parameters. The best amplitude decrement parameter (p<;0.001, AUC=0.80) was slightly better when compared to an expert rating (p<;0.001,AUC=0.79) with a correlation of (ρ=-0.13). Expert ratings correlated with the parameters opening velocity (p<;0.001,AUC=0.74,ρ=-0.43) and closing velocity (p<;0.001,AUC=0.66,ρ=-0.41). A newly defined parameter which combines amplitude decrement and opening velocity had an AUC=0.84 and correlated at 0.56 (p<;0.001) with the expert rating. These parameters representing bradykinesia in PD were algorithmically selected. We showed that the BradykAn system allows an independent analysis of individual components from hand motor tests and can be useful for clinical examination.