Objective: To develop and validate an automated algorithm for quantification of tremor from hand drawn Archimedes spirals.

Background: Spiral drawings are commonly used in clinics to identify and quantify tremor [2] [5]. Although digitising systems can analyse spiral characteristics, lack of time domain information makes analysis of pen-on-paper spirals challenging [4]. Accelerometry is a widely used electrophysiological technique to quantify tremor objectively [1][3]. We developed an algorithm to analyse pen-on-paper spirals without specialized digitising equipment for data capture and aimed to validate the spiral derived parameters against tri-axial accelerometer derived variables for tremor quantification.

Method: 15 subjects with upper extremity postural/action tremor and 15 healthy volunteers were recruited. Subjects were asked to produce free hand spirals which were scanned and processed by an automated algorithm to compute the mean deviation (MD) from a computer-generated ideal spiral. The derived parameter was compared to the Peak Power (PP) and Total Power (TP) of spectrum (1-30Hz) derived from tri-axial accelerometer power spectral density data.

Results: MD showed statistically significant strong correlation with tri-axial accelerometer derived power of the tremor spectrum for postural tremor (Spearman’s correlation for TP: MD, rho=0.465, p=0.010 and for PP: MD, rho= 0.521, p=0.003). MD was significantly different between tremor subjects and controls (p<0.001).

Conclusion: Automated analytic algorithms can generate clinically relevant variables to detect and quantify tremor from hand drawn spirals.

References: 1. Padraig E O’Suilleabhain and Joseph Y Matsumoto. Time-frequency analysis of tremors. Brain, 121(11):2127-2134, 1998. 2. Adriano O Andrade, Adriano Alves Pereira et al. Human tremor: origins, detection and quantification. In Practical Applications in Biomedical Engineering. InTech, 2013. 3. DechoSurangsrirat et al.Tremor assessment using spiral analysis in time-frequency do-main. In Southeastcon, 2013 Proceedings of IEEE, pp. 1-6. IEEE, 2013. 4. Seth L Pullman. Spiral analysis: a new technique for measuring tremor with a digitizing tablet. Movement Disorders, 13(S3):85-89, 1998. 5. Peter H Kraus and Arndt Homann. Spiralometry: computerized assessment of tremor amplitude on the basis of spiral drawing. Movement Disorders, 25(13):2164{2170, 2010

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MDS Abstracts - https://www.mdsabstracts.org/abstract/automated-analysis-for-quantification-of-tremor-from-pen-on-paper-archimedes-spirals/