Opening velocity, a novel parameter, for finger tapping test in patients with Parkinson's disease

Objectives: A new system consisting of an accelerometer and touch sensor was developed to find objective parameters for the finger tapping (FT) test in patients with Parkinson's disease (PD). Methods: We recruited sixteen patients with PD and thirty-two age-matched healthy volunteers (HVs). By using this new system, various parameters related to velocity, amplitude, rhythm and number in the FT test were measured in patients with PD and examined in comparison with those of HVs on the basis of the Unified Parkinson's Disease Rating Scale (UPDRS) FT score. Results: The new system allowed us to measure fourteen parameters of FT movement very easily, and a radar chart showed obvious differences in most of these parameters between HVs and patients with PD. Principal component analysis showed that fourteen parameters were classified into three components: (1) both mean and standard deviation (SD) of both amplitude and velocity, (2) number of FT for 60 s and mean FT interval, and (3) SD of FT interval. The first (velocity- and amplitude-related parameters) and third (rhythm-related parameters) components contributed to discrimination of PD from HVs. Maximum opening velocity (MoV) was the best of these parameters because of its sensitivity and association with the UPDRS FT score. Conclusions: A novel system for the FT test, which is compact, simple and efficient, has been developed. Velocity- and amplitude-related parameters were indicated to be valuable for evaluation of the FT test in patients with PD. In particular, we first propose that MoV is a novel marker for the FT test. (C) 2008 Elsevier Ltd. All rights reserved.