Pilot feasibility study of a semi-automated three-dimensional scoring system for cervical dystonia

The objective of this study is to test the feasibility of a semi-automated scoring system for the Toronto Western Spasmodic Torticollis Scale (TWSTRS) severity scale in patients with cervical dystonia. The TWSTRS requires training and experience. We previously developed a system to measure neck angle by analyzing three-dimensional position, obtained using Kinect, a marker-less three-dimensional depth sensor. The system can track patients' faces and bodies, automatically analyze neck angles, and semi-automatically calculate the TWSTRS severity scale score. We compared the TWSTRS severity scale scores calculated by the system with the video-based scores calculated by a neurologist trained in movement disorders. A correlation coefficient analysis was then conducted. Absolute accuracy was measured using intra-class correlation (ICC) (3,1), with 95% limits of agreement. To analyze the subscales, Cohen's kappa coefficient (kappa) was calculated. A p-value of <.05 was considered statistically significant. Thirty patients were enrolled. Their average age was 52.3 +/- 16.0 years, and the male to female ratio was 3:2. The average disease duration was 11.3 +/- 12.7 years. Total score measurements by the system were significantly correlated with those rated by the movement disorder-trained neurologist (r = .596, p <.05). There was a significant correlation (r =.655, p<.05) with regard to the automated part of the scale. An adequate ICC (3,1) of .562 was obtained for total severity score (p <.001, 95% confidence interval [CI]:.259-.765), while the equivalent score was.617 for the total automated part (p <.001, 95% CI.336-.798). Our three-dimensional motion capture system, which can measure head angles and semi-automatically calculate the TWSTRS severity scale score utilizing a single-depth camera, demonstrated adequate validity and reliability. This low-cost and portable system could be applied by general practitioners treating cervical dystonia to obtain objective measurements.