Williams S, Fang H, Relton SD, Wong DC, Alam T, Alty JE. Accuracy of Smartphone Video for Contactless Measurement of Hand Tremor Frequency.
Mov Disord Clin Pract 2021;
8:69-75. [PMID:
34853806 DOI:
10.1002/mdc3.13119]
[Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 09/14/2020] [Accepted: 10/20/2020] [Indexed: 11/05/2022] Open
Abstract
Background
Computer vision can measure movement from video without the time and access limitations of hospital accelerometry/electromyography or the requirement to hold or strap a smartphone accelerometer.
Objective
To compare computer vision measurement of hand tremor frequency from smartphone video with a gold standard measure accelerometer.
Methods
A total of 37 smartphone videos of hands, at rest and in posture, were recorded from 15 participants with tremor diagnoses (9 Parkinson's disease, 5 essential tremor, 1 functional tremor). Video pixel movement was measured using the computing technique of optical flow, with contemporaneous accelerometer recording. Fast Fourier transform and Bland-Altman analysis were applied. Tremor amplitude was scored by 2 clinicians.
Results
Bland-Altman analysis of dominant tremor frequency from smartphone video compared with accelerometer showed excellent agreement: 95% limits of agreement -0.38 Hz to +0.35 Hz. In 36 of 37 videos (97%), there was <0.5 Hz difference between computer vision and accelerometer measurement. There was no significant correlation between the level of agreement and tremor amplitude.
Conclusion
The study suggests a potential new, contactless point-and-press measure of tremor frequency within standard clinical settings, research studies, or telemedicine.
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