Objective: This study aims to introduce a novel video-based waveform analysis to objectively measure two fundamental tremor characteristics—rhythmicity and sinusoidality.
Background: Tremor is defined as involuntary, rhythmic, and sinusoidal movements. However, differentiating different types of tremors remains challenging due to overlapping features and the subjective nature of clinical evaluations.
Method: We defined parameters to reflect tremor characteristics, including the coefficient of variation of inter-peak intervals (CVIPI) for rhythmicity and the directionality index (DIN) for sinusoidality, based on waveforms derived from video-based analysis tracking the patients’ nose tip. We prospectively enrolled 13 cervical dystonia (CD) patients with head tremor for a validation study, simultaneously recording video-based and gyroscope-based tremor data. The algorithm was applied to 28 cervical dystonia and 22 ET cases using archived videos to evaluate individual and group characteristics of tremors.
Results: Video-based indices demonstrated excellent agreement with gyroscope-based measurements for peak frequency (ICC = 0.99) and the directionality index (ICC = 0.93), while the rhythmicity index (CVIPI) showed good reliability (ICC = 0.86). In the application study, ET cases were predominantly rhythmic and sinusoidal, although certain cases showed reduced values for these parameters. However, head tremors in CD generally exhibited lower rhythmicity and sinusoidality compared to ET cases, despite some dystonic cases displayed highly rhythmic and sinusoidal waveforms. These findings highlight the overlapping features between ET and cervical dystonia with head tremor, underscoring the variability within tremor syndromes based on rhythmicity and sinusoidality.
Conclusion: Video-based analysis of tremor waveforms offers an objective evaluation of rhythmicity and sinusoidality, providing a valuable tool for the precise and objective description of tremor syndromes.
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To cite this abstract in AMA style:
JH. Shin, SM. Lee, KA. Woo, H. Jinnah, M. Hallett, V. Fung, S. Pandey, R. Helmich, M. Vidailhet, A. Shaikh, A. Fasano, HJ. Kim, B. Jeon. Waveform based analysis of cervical dystonia with tremor and essential tremor using a marker-less tracking algorithm with 2D-video: evaluation of sinusoidality and rhythmicity [abstract]. Mov Disord. 2025; 40 (suppl 1). https://www.mdsabstracts.org/abstract/waveform-based-analysis-of-cervical-dystonia-with-tremor-and-essential-tremor-using-a-marker-less-tracking-algorithm-with-2d-video-evaluation-of-sinusoidality-and-rhythmicity/. Accessed October 5, 2025.« Back to 2025 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/waveform-based-analysis-of-cervical-dystonia-with-tremor-and-essential-tremor-using-a-marker-less-tracking-algorithm-with-2d-video-evaluation-of-sinusoidality-and-rhythmicity/