title: Grip force behavior in Gilles de la Tourette syndrome.
abstract: We analyzed predictive and reactive grip force behavior in 15 patients with Gilles de la Tourette syndrome (GTS) and 15 sex- and age-matched healthy control subjects. Nine patients were without medication; six patients were on medication. In a first experiment, participants lifted and held instrumented objects of different weight. In a second experiment, participants performed vertical point-to-point and continuous arm movements at different frequencies with a hand-held object. In a third experiment, preparatory and reactive grip force responses to sudden load perturbations were analyzed when a weight was dropped into a hand-held cup either by the subject or unexpectedly by the experimenter. Compared to the healthy subjects, GTS patients had increased grip forces relative to the load force in all tasks. Despite this finding, they adjusted the grip force to changes in load force (due to either a change in the mass lifted or accelerating the mass during continuous movements) in the same way as healthy subjects. The temporal coupling between grip and load force profiles was also similar in patients and healthy controls, and they displayed normal anticipation of impact forces when they dropped a weight into a hand-held cup. We found no significant effect of medication on the performance of GTS patients, regardless of the task performed. These results are consistent with deficient sensory-motor processing in Gilles de la Tourette syndrome.
authors.affiliation: Sobell Department of Motor Neuroscience and Movements Disorders, Institute of Neurology, University of London, London, United Kingdom. dr.dennis.nowak@gmx.de
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Nowak
authors.forename: John
authors.initials: J
authors.lastname: Rothwell
authors.forename: Helge
authors.initials: H
authors.lastname: Topka
authors.forename: Mary M
authors.initials: MM
authors.lastname: Robertson
authors.forename: Michael
authors.initials: M
authors.lastname: Orth
mesh_terms: D000054:Acceleration; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001132:Arm / Q000503:physiopathology; D001696:Biomechanical Phenomena / Q000379:methods; D016022:Case-Control Studies; D002648:Child; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D017770:Lifting; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D011237:Predictive Value of Tests; D011597:Psychomotor Performance / Q000502:physiology*; D013647:Task Performance and Analysis; D005879:Tourette Syndrome / Q000503:physiopathology*