New insight in spiral drawing analysis methods - Application to action tremor quantification.

Area of Science:

• Neurology
• Biomedical Engineering
• Signal Processing

Background:

• Spiral drawing tests are standard for assessing tremor severity in clinical trials.
• Current visual rating by experts is subjective and prone to inter-rater variability.
• Mathematical signal analysis offers potential for objective tremor assessment.

Purpose of the Study:

• To propose novel numerical methods for analyzing spiral drawings.
• To evaluate these methods for agreement with visual ratings.
• To assess the reproducibility of numerical tremor assessment.

Main Methods:

• Visual rating of essential tremor patient spiral drawings by movement disorder experts.
• Application of velocity analysis, static unraveling, dynamic unraveling, and empirical mode decomposition.
• Estimation of reproducibility and agreement between visual and numerical ratings.

Main Results:

• Excellent agreement was found between visual and numerical tremor ratings.
• Numerical methods demonstrated superior reproducibility compared to visual ratings.
• Static and dynamic unraveling showed less dispersion and ease of automatic analysis.

Conclusions:

• Proposed numerical methods provide reliable tremor severity scores.
• Implementation on digitized tablets offers an efficient, automatic tool for tremor assessment.
• These automated approaches can enhance the objectivity and efficiency of tremor evaluation.