Spiral drawing time as a measure of bradykinesia.

Background and purpose: Bradykinesia, which is commonly defined as slowness of movements, is one of the cardinal signs of Parkinson's disease (PD) and parkinsonian syndromes. Simple clinical rating scales are used commonly to measure bradykinesia in routine clinical practice although this kind of assessment is biased. The aim of the study was to evaluate the time of spiral drawing as a measure of bradykinesia. Materials and methods: Fifty-four patients with PD and 39 healthy age- and sex-matched volunteers were examined. The severity of parkinsonism was assessed using UPDRS and bradykinesia was assessed using instrumental methods: the BRAIN test, Nine-Hole PEg Board (NHPB) test and Quantitative Tremor Analysis on the Graphicc Digitizing Tablet (QTAGDT). QTAGDT registers patients' hand movements during the spiral drawing task and generates several data characterizing tremor and the spiral drawing time as an additional result. Results: The spiral drawing time was significantly longer in PD patients when compared to normal controls (p<0.001). The bradykinesia assessment using the spiral drawing time showed a significant correlation with the clinical ratings score of the UPDRS (R = 0.64, p = 0.001) and with the results of other instrumental methods: the BRAIN Test and NPHB test (R = -0.52, p = 0.0007, R = 0.55, p = 0.03, respectively). Hand tremor seemed to have no impact on bradykinesia assessment, and the new method was found to be highly test-retest reliable (R = 0.95, p < 0.0001). Conclusion: The spiral drawing time is a simple, quick and objective assessment of upper limb bradykinesia.