Kinematic Analysis of Handwriting in Parkinson Disease

Tremor is considered one of the most common disturbances of movement especially in Parkinson’s disease (PD). To date there is not a unique methodology, test or parameter for the measurement of tremor. The objective of this study was to identify a set of tests and of kinematic parameters differentiating the writing of a PD subject from a normal, exploiting the tremor. To this aim, the writing movements of 22 PD patients and of 17 control subjects were analyzed. Each subject was asked to perform three tests: five horizontal straight lines (HSL), Archimedes’ Spiral (AS) and overlapping circles (C). The results showed that significant differences between subjects with Parkinson's disease and controls are recognizable, in all tests, especially in AS and C tests, requiring greater attention and coordination to perform a fast movement within a delimited space. Furthermore, some kinematic parameters measuring curvilinear velocity (on the whole trace as well as within a stroke) and trace fragmentation (stroke length and duration and #stroke/cm) were capable of differentiating significantly the two groups. In conclusion, kinematic analysis can be successfully used in the study of tremors and combined with suitable curvilinear tests can differentiate PD patients from normal subjects.