Digitized Spiral Analysis Differentiates Dystonia Patients from Control (P1.039)

Objective: To characterize brachial dystonia in DYT1 and DYT6 dystonia using digitized Archimedes spiral drawing. Background: Measures for detection and quantification of dystonia are needed. Assessments of drawing and writing present an opportunity to objectively evaluate individuals with brachial dystonia. Digitized spiral analysis is a non-invasive test that has demonstrated discriminative value in Parkinson disease and essential tremor, but is not well described in brachial dystonia. It captures kinematic, dynamic, and spatial attributes of freely drawn Archimedes spirals, and computes a series of spiral indices to quantify motor performance. Methods: 27 dystonia patients (mean age: 33yrs; 8-66) with mutations in TOR1A (DYT1)(n=15) or THAP1 (DYT6)(n=12) and 27 controls (mean age 40yrs; 20-66) drew 10 spirals with each hand on a digitizing tablet. Spirals from the affected arm (21 right, 6 left) were compared to 27 controls matched for age and handedness (24 right, 3 left; mean age 40yrs; 20-66). In bi-brachial patients, the dominant arm was analyzed. Results: Dystonia subjects showed worse spiral severity scores compared to controls (1.58 vs 0.59, p<0.0001). Overall pressure was not different (195.0 vs 190.2) but measures of pressure frequency (1.29 vs 0.34, p<0.0001), and power (3.25 vs 0.55, p=0.0002) were greater in dystonic subjects. Measures of spiral irregularity, including spiral smoothness (-3.3 vs -4.8, p=0.001), the residue of radius versus Theta (0.32 vs 0.23, p=0.0002), and width variability (0.388 vs 0.239, p<0.0001) were abnormal. Mean speed did not differ between groups. No differences were found comparing THAP1 to TOR1A. Conclusions: Digitized spirals reveal quantifiable differences in genetic forms of brachial dystonia compared to controls. Overall spiral severity, is worse, measures of spiral shape, pressure frequency and power are abnormal. Further study is warranted to determine how spiral indices correlate with other features of dystonia, or help discriminate dystonia from other movement disorders. Disclosure: Dr. Ratliff has nothing to disclose. Dr. Mirallave has nothing to disclose. Dr. Ortega has nothing to disclose. Dr. Glickman has nothing to disclose. Dr. Yu has nothing to disclose. Dr. Raymond has nothing to disclose. Dr. Bressman has nothing to disclose. Dr. Pullman has nothing to disclose. Dr. Saunders-Pullman has nothing to disclose.