Tetras spirals and handwriting samples: Determination of optimal scoring examples

Background: Spiral drawings and handwriting tasks have long been used to assess the severity of essential tremor, but these motor tasks are somewhat less objective as the rules for scoring are not based on firm objective amplitude-based criteria. Publishing the best examples of each of the possible 0–4 ratings for these items could reduce scoring variance. Methods: 21 members of the Tremor Research Group each rated 94 spirals and 64 handwriting samples using TETRAS scoring criteria. For each sample, the most frequently reported score (mode; maximum of 21) was determined. Ratings not adjacent to the mode were subtracted from the number of mode scores, to calculate a total value. For each of the ratings (0, 1, 1.5, 2, 2.5, 3, 3.5, 4), the samples with the highest total value were selected as best examples. Results: In general, rater agreement was good for spirals but poor for handwriting samples. Nevertheless, examples with excellent agreement were identified for all spiral and handwriting ratings, and are presented. Conclusion: Best examples for scoring spirals and handwritings are needed to reduce the variance of TETRAS scores in clinical trials and clinical practice.