Evaluating factors that can influence spirography ratings in patients with essential tremor.

Spirograph drawings are used in most comprehensive assessments of essential tremor (ET). Nevertheless, several different paradigms are used and no effort has been made to compare these. We used two different cohorts to assess different aspects of spiral rating. In the first, we had subjects simulate different levels of effort by writing (1) 'normally', (2) 'slowly and carefully', (3) 'softly', and (4) 'rapidly' using both their dominant and non-dominant hands. In the second, subjects (1) drew in between the lines of two drawn spirals, (2) traced a previously drawn spirograph, and (3) drew freehand. Subjects drew each with both 'supported' (regular writing) and 'unsupported' writing. The spirals were coded, randomized and blindly rated on a 0-9 scale. Unsupported drawings were consistently rated as worse than supported spirals, and the dominant hand was generally better than the non-dominant hand. Spiral drawn freehand spirals were consistently rated with the lowest scores. Inter-rater and intra-rater reliability were also best for unsupported drawings and tended to be best for 'freehand'. 'Effort' had little effect on ratings. Based on our results, we recommend that assessment of ET include unsupported, freehand spirals.