Ambulatory accelerometry to quantify involuntary movements and tics in thesyndrome of Gilles de la Tourette

Gilles de la Tourette syndrome is a chronic neuropsychiatric disorder chara cterized by recurrent and involuntary tics, in addition to complex behavior al symptoms. Objective quantification of the nonspecific movements in Toure tte patients can contribute much to understanding the pathophysiology of th is disease. We used three accelerometers to characterize head movement patt erns and to objectively quantify head motility in the lateral, sagittal, an d transversal planes in 9 Tourette patients and 14 controls during periods of rest, conversation, and watching a videotape with an entertaining progra m. Characteristic head movement patterns can be documented by means of acce lerometry. Head motility levels in the lateral, sagittal, and transversal p lanes were significantly higher in the patients than in the controls during all the procedures. The patients and the controls showed a similar signifi cant increase in head motility during conversation, but not during video wa tching. This first study shows that for both standardized and ambulatory re search, accelerometry may provide an objective tool by which to quantify th e severity and temporal dynamics of tics or nonspecific movements.