Dalarna University's logo and link to the university's website

Objective: To define and evaluate a computer method for assessing drawing impairment in spiral drawings. To define an overall score, summarizing self-assessments and motor test data from a test battery for patients with advanced Parkinson's disease (PD). Background: A test battery, consisting of self-assessments (modified PDQ-8) and motor tests (tapping and spiral drawing) was developed for a hand computer with touch screen in a telemedicine setting. Assessments and tests were carried out four times per day in a group of 65 patients with advanced PD (Duodopa treated or candidates) during 1-6 weekly test periods each. For most test periods, UPDRS ratings were available. Methods: In a web interface, a PD specialist assessed drawing impairment in 505 selected spiral drawings, representing all categories on the Bain & Findley 10-category scale. A computer method, using wavelet transforms and principal component analysis, processed the same spirals to generate a 'spiral score'. According to the PD specialist and co-author Dr Nyholm, the information content of a test period with the test battery could be descibed by six dimensions, 'off', 'dyskinesia', 'walking', 'satisfaction', 'spiral', and 'tapping'. Each dimension was defined as the first principal component of the level (mean) and fluctuation (standard deviation) for the questions or tests that this dimension is based on. Tapping dimension was based on both speed and accuracy. To obtain weights for an overall score, linear regression of the dimensions vs. simultaneous UPDRS ratings was performed. To assess the internal consistency of the test battery, Cronbach's Alpha for the six dimensions was calculated. Results: Pearson correlation between spiral score and clinical rating of drawing impairment was 0.87. Weights in overall test score were (%): spirals, 41, tapping, 24, satisfied, 19, dyskinetic, 10, walking, 5.4 and off, 0.1. Internal consistency for the dimensions was 0.81. Conclusions: The computer generated spiral score was strongly correlated to clinical assessment of drawing impairment. Spirals were assigned highest weight in overall score, reflecting the high weight of motor function in total UPDRS. Internal consistency was strong, implying all dimensions represent aspects of a common characteristic.