Objective: To assess repetitive tapping movements (RTM) using a slow motion camera and compare them with a clinician visual impression in people that have been risk stratified for future Parkinson’s in the PREDICT-PD study. Second, to compare the RTM in these participants to the RTM in PD patients.

Background: Bradykinesia is the defining motor symptom in Parkinson’s disease [1]. The standard rating method for bradykinesia is a qualitative clinician assessment of repetitive movements, in particular when performing a tapping test. The variation between examiners is a limitation to assessing this feature.

Method: This is a cross-sectional study based on RTM motor assessment using a slow motion camera and clinician impression using motor score of the Unified Parkinson’s Disease Rating Scale (UPDRS). Two patients with PD (a 75-year old man and a 70-year old woman) and 35 healthy controls (males =, females=, age 75 ± 5) were included for comparison. For each participant, finger tapping were recorded during 20 s using a smartphone at 240 frames/s (slow motion capture). All the videos were analysed using novel Python scripts (a general-purpose programming language). The distal segments of first and second fingers were tracked using the discriminative correlation filter with channel and spatial reliability [2]. Two kinetic parameters were analysed: amplitude between fingers and frequency (number of taps/s). Linear regression was used to determine the trend of movement over time [graph 1].

Results: Patient 1 and 2 had a 5 and 2-year history of PD, respectively. On the examination, both asymmetric parkinsonism. In the ‘off’ state, their UPDRS-III overall scores were 45 and 47, respectively; and they scored 2 and 3 in finger tapping section of the UPDRS on the most affected side respectively. In healthy controls, the average of UPDRS-III overall score was 4 ±4. Patients with PD had greater decrement in amplitude than controls (-2.4 and -3.1 versus -0.3). No differences in decrement in frequency were observed between the two groups were found: -0.2 and 0.05 in PD patients vs -0.2 in controls.

Conclusion: The preliminary results suggest it is an accessible way to quantify the kinetic parameters of repetitive movements. In particular, decrement in amplitude seems useful to differentiate both groups. Future directions will be to study if this method is able to detect subtle motor changes in early stages of PD.

References: [1] Sahay A, Duker AP, Payne M, et al. The modified bradykinesia rating scale for Parkinson’s disease: Reliability and comparison with kinematic measures. Mov Disord. 2011 Aug 15;26(10):1859-63. [2] Lukežič A, Vojíř T, Čehovin Zajc L, Matas J, Kristan M. Discriminative Correlation Filter Tracker with Channel and Spatial Reliability. Int J Comput Vis. 2018;126(7):671-688. doi:10.1007/s11263-017-1061-3.

« Back to 2019 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/slow-motion-analysis-of-repetitive-tapping-smart-a-pilot-study-of-a-new-measurement-of-bradykinesia/