COMPUTATIONAL ANALYSIS OF OPEN-LOOP HANDWRITING MOVEMENTS IN PARKINSONS-DISEASE - A RAPID METHOD TO DETECT DOPAMIMETIC EFFECTS

We used a computational analysis of open loop handwriting movements an d a clinical rating scale for monitoring the effect of apomorphine in 16 patients with early untreated parkinsonism [subsequently L-DOPA res ponsive, probable Parkinson's disease (PD)], six patients with long-st anding PD with L-DOPA associated motor fluctuations, and seven patient s with known L-DOPA unresponsive parkinsonism. Subjects were instructe d to write fluently concentric circles of similar to 12 mm in diameter . Movements were recorded for two periods of 3 s each, using a digitiz ing tablet. Mean peak velocity (V-max) and mean peak acceleration (A(m ax)) were determined. In addition, two sensitive indices describing th e degree of automation of handwriting were derived: (a) NCV, calculate d as the mean Number of Changes in direction of Velocity per half circ le, and (b) NCA, the mean Number of Changes in the direction of Accele ration. Clinical rating was performed according to the Unified Parkins on's Disease Rating Scale part III (UPDRS III). After apomorphine inje ction, the patients with early untreated probable PD showed significan t improvement of V-max, A(max), NCV, NCA, and UPDRS III scores. Likewi se, the patients with long-standing PD improved significantly in all k inematic parameters and UPDRS III scores. Patients with L-DOPA unrespo nsive parkinsonism failed to change significantly in any of the parame ters tested. These observations suggest that the computer-assisted ana lysis of automated handwriting movements can be used as an objective q uick method for quantifying dopamimetic effects on the kinematics of h andwriting movements in parkinsonian patients.