Objective: To examine the feasibility of using a three-dimensional (3D) optical device served as tremor amplitude detection, we determined correlation between its results and clinical tremor rating scale.

Background: Tremor severity is usually evaluated by clinical scale alone, not by oscillatory amplitude. Tremor amplitude is relatively hard to assess without using a complex device system. We developed three different algorithms to quantify essential tremor amplitudes using a small 3D optical device, and correlated the results with clinical severity scores.

Methods: We enrolled eleven patients with essential tremor, all accessed with Fahn-Tolosa-Marin (F-T-M) Tremor scale by a movement disorder specialist. Tremor amplitude presented in X, Y, Z direction is measured by an optical device (Leap Motion Inc. USA) was further analyzed under three algorithms: (1) dispersion, (2) 2D Threshold, and (3) 3D Envelop. The dispersion is described in a previous study (Matsumoto, Dodick et al., 1999). 2D Threshold calculateed finger shakes larger than 0.8 mm in frontal plane. 3D envelope was defined as the Peak-to–peak of an envelope. Correlation between the mean amplitudes determined by these algorithms and the clinical scores (F-T-M scores) were then determined.

Results: The tremor amplitude determined by the 3D Envelop is with higher correlation (R=0.74) to the clinical scale than that by dispersion or 2D Threshold.

Conclusions: Tremor amplitude measured by the 3D Envelop is with high correlation to clinical FTM tremor scale. The 3D small optical device with our developed algorithms could be a useful tool for objectively quantifying tremor severity in clinical environments.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tremor-amplitude-detected-by-three-dimensional-optical-device-provides-good-correlation-to-clinical-rating-scale/