Longardner Katherine, Shen Qian, Tang Bin, Wright Brenton A, Kundu Prantik, Nahab Fatta B
Department of Neurosciences, University of California San Diego, San Diego, CA, USA.
Department of Psychiatry, University of California San Diego, San Diego, CA, USA.
Digit Biomark. 2024 Jul 20;8(1):140-148. doi: 10.1159/000539529. eCollection 2024 Jan-Dec.
Essential tremor is a common movement disorder. Numerous validated clinical rating scales exist to quantify essential tremor severity by employing rater-dependent visual observation but have limitations, including the need for trained human raters and the lack of precision and sensitivity compared to technology-based objective measures. Other continuous objective methods to quantify tremor amplitude have been developed, but frequently provide unitless measures (e.g., tremor power), limiting real-world interpretability. We propose a novel algorithm to measure kinetic tremor amplitude using digital spiral drawings, applying the V3 framework (sensor verification, analytical validation, and clinical validation) to establish reliability and clinical utility.
Archimedes spiral drawings were recorded on a digitizing tablet from participants ( = 7) enrolled in a randomized placebo control double-blinded crossover pilot trial evaluating the efficacy of oral cannabinoids in reducing essential tremor. We developed an algorithm to calculate the mean and maximum tremor amplitude derived from the spiral tracings. We compared the digitally measured tremor amplitudes to manual measurement to evaluate sensor reliability, determined the test-retest reliability of the digital output across two short-interval repeated measures, and compared the digital measure to kinetic tremor severity graded using The Essential Tremor Rating Assessment Scale (TETRAS) score for spiral drawings.
This algorithm for automated assessment of kinetic tremor amplitude from digital spiral tracings demonstrated a high correlation with manual spot measures of tremor amplitude, excellent test-retest reliability, and a high correlation with human ratings of the TETRAS score for spiral drawing severity when the tremor severity was rated "slight tremor" or worse.
This digital measure provides a simple and clinically relevant evaluation of kinetic tremor amplitude that shows promise as a potential future endpoint for use in clinical trials of essential tremor.
特发性震颤是一种常见的运动障碍。现已有许多经过验证的临床评分量表，通过依赖评估者的视觉观察来量化特发性震颤的严重程度，但这些量表存在局限性，包括需要经过培训的人员进行评估，并且与基于技术的客观测量方法相比，缺乏精确性和敏感性。已经开发出其他连续的客观方法来量化震颤幅度，但这些方法通常提供无量纲的测量值（例如，震颤功率），限制了在实际应用中的可解释性。我们提出了一种使用数字螺旋图测量动态震颤幅度的新算法，并应用V3框架（传感器验证、分析验证和临床验证）来确定其可靠性和临床实用性。
在一项评估口服大麻素减少特发性震颤疗效的随机安慰剂对照双盲交叉试验中，从参与者（n = 7）在数位板上记录阿基米德螺旋图。我们开发了一种算法，用于计算从螺旋轨迹得出的平均和最大震颤幅度。我们将数字测量的震颤幅度与手动测量进行比较，以评估传感器的可靠性，确定在两个短时间间隔重复测量中数字输出的重测可靠性，并将数字测量结果与使用特发性震颤评分评估量表（TETRAS）对螺旋图进行的动态震颤严重程度分级进行比较。
这种用于从数字螺旋轨迹自动评估动态震颤幅度的算法，与震颤幅度的手动点测量具有高度相关性，具有出色的重测可靠性，并且当震颤严重程度评为“轻度震颤”或更严重时，与TETRAS评分的人类评级对螺旋图严重程度具有高度相关性。
这种数字测量方法为动态震颤幅度提供了一种简单且与临床相关的评估，显示出有望成为特发性震颤临床试验中潜在的未来终点。
