Reliability of Finger Tapping Test Used in Diagnosis of Movement Disorders

We tested the repeatability of a finger tapping device with magnetic sensors to determine its reliability. This device, which was developed to assist in the diagnosis of movement disorders such as Parkinson's disease (PD) and strokes, was used to measure the distance between the thumb and index fingers during finger tapping movements (repeatedly opening and closing the gap between the thumb and forefinger). We evaluated three types of repeatability based on the interclass correlation coefficient (ICC) and analysis of variance (ANOVA), i.e., repeatability when movements were measured at different times, that when movements were measured with different devices, and that when movements were measured by different measurers. We analyzed these three types for three finger tapping tasks on both hands for 21 characteristics calculated from finger tapping waveforms. As a result, repeatability when using different devices was high regardless of the task or which hand was used. Repeatability when movements were measured at different times and when different measurers were used was high in some tasks, but not all. One of the finger tapping tasks (finger tapping movement with the largest amplitude and highest velocity), which is used in a conventional method of diagnosing PD (UPDRS), did not have sufficient repeatability, while the other tasks exhibited high repeatability. These results clearly demonstrate that this device is extremely reliable.