Objective: This study evaluates the accuracy of frequency measurement in comparison to the accelerometric electromygraphic analysis on hand and head tremor patients.

Background: The Microsoft Kinect® System provides a potentially low-cost solution for clinical and home-based measurement of tremor.

Methods: 12 patients (79 assessments) with head tremor and 5 patients (16 assessments) with hand tremor were simultaneously measured with a 4-channel-EMG, a linear 2-channel accelerometer (ACC, frame rate: 192Hz) and a Microsoft Kinect® V2 camera (RGB camera, infrared-based depth sensor; frame rate: 30fps). The Kinect system derived in real time motion trajectories from 25 mathematically detected skeleton (hand) and face points (head). All patients were recorded in seated rest for 30 seconds performing six (head) and five (hand) motor tasks. Peak tremor frequency (primary outcome) was assessed using a DFT within the 1 to 30Hz band. As a qualitative measure we compared the number of recordings in which a tremor peak was detected by ACC, EMG and Kinect. The offset in peak tremor frequency detected by Kinect and EMG/ACC, respectively, was quantified by a Bland-Altman-Plot.

Results: Out of 79 head tremor assessments, ACC, EMG and Kinect detected tremor in 28, 35 and 26 cases. In 15 cases, tremor was detected concurrently by ACC and Kinect with an offset estimated by Bland-Altman-Plot of 0.005Hz (limits of agreement (LOA): -0.62/0.61Hz) and 0.01Hz (LOA: -0.35/0.37Hz) for EMG vs. Kinect (n=16). Out of 32 hand tremor assessments (16 each hand), ACC, EMG and Kinect detected a tremor in 14, 13 and 12 recordings. Bland-Altman-Plot revealed an offset of 0.04Hz (LOA -1.06/1.13Hz) between ACC vs. Kinect (n=8) and -0.14Hz (LOA: -2.13/1.01Hz) between EMG vs. Kinect (n=6).

Conclusions: The Kinect camera system is suitable to detect both, hand and head tremor with a negligible offset. Although Kinect detected tremor in nearly as many cases as the gold standard, concurrent detection of tremor by Kinect/EMG and Kinect/ACC occurred in only 50% of cases. Thus, further studies are needed to define the sensitivity of the Kinect system to detect low amplitude tremor (Kinect negative, ACC/EMG positive). Cases in which tremor was detected solely by Kinect are of specific interest as Kinect might be superior to EMG/ACC here.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/video-based-tremor-analysis-via-kinect-system-in-comparison-to-accelerometric-and-electromyographical-tremor-detection/