FUNCTIONAL ASYMMETRIES IN THE MOVEMENT KINEMATICS OF PATIENTS WITH TOURETTES-SYNDROME

Objectives-This study adopted a concurrent task design and aimed to qu antify the efficiency and smoothness of voluntary movement in Tourette 's syndrome via the use of a graphics tablet which permits analysis of movement profiles. In particular, the aim was to ascertain whether a concurrent task (digit span) would affect the kinematics of goal direc ted movements, and whether patients with Tourette's syndrome would exh ibit abnormal functional asymmetries compared with their matched contr ols. Methods-Twelve patients with Tourette's syndrome and their matche d controls performed 12 vertical zig zag movements, with both left and right hands (with and without the concurrent task), to large or small targets over long or short extents. Results-With short strokes, contr ols showed the predicted right hand superiority in movement time more strongly than patients with Tourette's syndrome, who instead showed gr eater hand symmetry with short strokes. The right hand of controls was less force efficient with long strokes and more force efficient with short strokes, whereas either hand of patients with Tourette's syndrom e was equally force efficient, irrespective of stroke length, with an overall performance profile similar to but better than that of the con trols' left hand. The concurrent task, however, increased the force ef ficiency of the right hand in patients with Tourette's syndrome and th e left hand in controls. Conclusions-Patients with Tourette's syndrome , compared with controls, were not impaired in the performance of fast , goal directed movements such as aiming at targets; they performed in certain respects better than controls. The findings clearly add to th e growing literature on anomalous lateralisation in Tourette's syndrom e, which may be explained by the recently reported loss of normal basa l ganglia asymmetries in that disorder.