Differences in Writing and Drawing may Help Differentiate Parkinson’s Disease from Essential Tremor

Abstract

Introduction: The ability to draw figures requires preserving visuospatial functions and motor pathways. The floating door sign (FDS) reflects the inability to join the vertical lines of a door with the floor when a patient is asked to draw a house. This signal was described as a positive predictive factor for Parkinson’s Disease (PD), but not essential tremor (ET). Nevertheless, conflicting literature has emerged recently. We aim to evaluate the features of the FDS and other graphomotor tasks in patients with PD and ET.
Methods: Patients recruited from 2 hospital centers were asked to draw 3 pictorial elements (house, flower, and sun), write a sentence and perform 2 cognitive evaluations (pentagons copy and clock drawing test). Clinical and demographic characteristics from both groups were obtained.
Results: A total of 54 patients (PD: 38; ET: 16) were included. FDS was more prevalent in PD patients (PD: 45% vs ET: 6%; p = 0.005), who also drew a significantly smaller house. PD patients drew a sun with a significantly smaller diameter, increased number of smaller sunbeams and a higher distance sun-sunbeam. Additionally, a significantly smaller flower and lower, flatter petals, with an increase distance petalsflower were also found in the PD patients’ group. Comparing PD patients with positive versus negative FDS, we found that those with a positive FDS scored less on the pentagons copy (4.1 ± 1.8 vs 5.2 ± 1.2; p=0.025), with no significant differences in the UPDRS motor or micrographia-related scores.
Conclusion: Graphomotor tasks, including the FDS, can be useful in the distinction of patients with PD and ET. The presence of the FDS could be associated to a mild visuospatial cognitive dysfunction. This potential interplay warrants further exploration in future studies.