Abnormal topography of EEG microstates in Gilles de la Tourette syndrome.

Quantitative analysis of scalp EEGs was performed on 13 patients with Gilles de la Tourette syndrome (GTS) and 25 matched controls. The analysis method was adaptive segmentation, which describes the topography and sequence of brain electric fields in continuous EEG. The GTS patients showed an abnormal increase in fields with a right-frontal/left-posterior configuration. The GTS patient's EEGs did not differ from normal controls in the average duration of the brain electric microstates, field stability and EEG carrier frequency. To find out whether the abnormal activity is similar to movement-related activity a simple and a complex motor task were performed. Both tasks led to distinct changes of brain electric activity, but not to an increase in right-frontal-/left-posterior-oriented patterns. Motor-related activity was contrasted with two auditory tasks. We conclude that GTS patient's EEG show abnormal topographic patterns of brain electric activity. Unlike other psychiatric disorders, the temporal descriptors of the EEG aspects are unaffected. The abnormal EEG patterns in GTS patients are not similar to those elicited by simple or complex movements; thus, the presence of abnormally facilitated, near-threshold motor activity in GTS patients seems not a likely explanation.