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

Gilles de la Tourette syndrome is a chronic neuropsychiatric disorder characterizedby recurrent and involuntary tics, in addition to complex behavioral symptoms. Objective quantification of the nonspecific movements in Tourette patients can contribute much to understanding the pathophysiology of this disease. We used three accelerometersto characterizehead movement patterns and to objectively quantify head motility in the lateral, sagittal, and transversal planes in 9 Tourette patients and 14 controls during periods of rest, conversation, and watching a videotape with an entertaining program. Characteristic head movement patterns can be documented by means of accelerometry. Head motility levels in the lateral, sagittal, and transversal planes were significantly higher in the patients than in the controls during all the procedures. The patients and the controls showed a similar significant increase in head motility during conversation, but not during video watching. This first study shows that for both standardized and ambulatory research, accelerometry may provide an objective tool by which to quantify the severity and temporal dynamics of tics or nonspecific movements.