Objective: To quantify appendicular bradykinesia during a repetitive motor task in patients with Parkinson’s disease.

Background: Bradykinesia is a cardinal motor symptom of Parkinson’s Disease (PD). While clinical visual assessment remains the gold standard, quantifying appendicular bradykinesia using objective wearable sensors can increase the sensitivity and precision of the assessment during a short duration clinical trial. Wearable sensors are commonly used to quantify bradykinesia and decrement (decrease in speed of the movement over time) during repetitive movement tasks [1].

Methods: 8 patients with advanced PD receiving levodopa via enteral pump (Duopa®) wore a sensor containing a triaxial accelerometer, gyroscope, and magnetometer on each wrist (APDM, Inc). The patients performed a repetitive wrist pronation-supination task for 15 seconds (one trial) with their left hand both ON and OFF medication (L-DOPA pump) [2]. The continuous sensor data was split into individual movements consisting of one full hand rotation. Features were calculated from the gyroscope sensor (angular velocity) for the individual movements using MATLAB and then averaged together for each trial. The features included both average and standard deviation for maximum velocity, range of velocity, and root-mean-square (RMS) velocity. Decrement was quantified by calculating the slope of a linear regression line fit to the feature data within each trial, and by computing the ratio of movements in the first half of the trial compared to movements in the second half of the trial. Results between the ON and OFF conditions were compared using paired t-tests.

Results: Three bradykinesia features differentiated between ON and OFF conditions: standard deviation of maximum velocity, range of velocity, and RMS velocity (p<0.05). For decrement, the ratio of maximum velocity and range of velocity between the first half and second half of the trial were significantly different between ON and OFF conditions (p<0.05). The linear regression of the maximum velocity displayed a trend to significance between ON and OFF (p=0.06).

Conclusions: Wearable sensors reliably quantified features of bradykinesia and detected a therapeutic response to L-DOPA in advanced PD. These results provide a rationale for including quantitative motor assessment of bradykinesia using wearable sensors in clinical trials of PD.

References: [1] Salarian A, Russmann H, Wider C, Burkhard PR, Vingerhoets FJ, Aminian K. Quantification of tremor and bradykinesia in Parkinson’s disease using a novel ambulatory monitoring system. IEEE Transactions on Biomedical Engineering (2007); 54(2): 313-322. [2] Van den Noort JC, Verhagen R, van Dijk KJ, et al. Quantification of hand motor symptoms in Parkinson’s disease: a proof-of-principle study using inertial and force sensors. Annals of Biomedical Engineering (2017); 45(10): 2423-2436.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/quantitative-assessment-of-appendicular-bradykinesia-in-parkinsons-disease-using-wearable-sensors/