Gilles de la Tourette syndrome (GTS) is characterized by multiple fluctuating motor and vocal tics. These tics are often preceded by premonitory phenomena including the urge to move, or by exaggerated bodily sensations that can lead to considerable disability and difficulties with attention and concentration. In the past the premonitory phenomena were interpreted as the driving force behind tics. However, there is not always a clear sequence of premonitory sensations followed by a tic. Also, the former typically develop around the age of 10 years, i.e. after the onset of the latter. Thus, the relationship between premonitory phenomena and tics is unclear. The present article reviews the current knowledge on this issue. Neurophysiological studies have shown some abnormalities of sensorimotor integration in GTS. In addition, structural imaging (MRT) has demonstrated a thinning of the sensorimotor cortex in children and adolescents with GTS. In contrast, an increase in fractional anisotropy as a marker of the directionality of white matter fibers underneath the pre- and postcentral gyrus has been demonstrated in adult GTS patients. These data underscore the role of developmental abnormalities and reorganisation in the somatosensory system in GTS warranting further studies. Multimodal studies including structural and functional imaging and electrophysiology in clinically well characterized GTS subgroups might foster a better understanding of somatosensory phenomena and the role of sensorimotor circuits in GTS.
Gilles de la Tourette syndrome (GTS) is characterized by multiple fluctuating motor and vocal tics. These tics are often preceded by premonitory phenomena including the urge to move, or by exaggerated bodily sensations that can lead to considerable disability and difficulties with attention and concentration. In the past the premonitory phenomena were interpreted as the driving force behind tics. However, there is not always a clear sequence of premonitory sensations followed by a tic. Also, the former typically develop around the age of 10 years, i.e. after the onset of the latter. Thus, the relationship between premonitory phenomena and tics is unclear. The present article reviews the current knowledge on this issue. Neurophysiological studies have shown some abnormalities of sensorimotor integration in GTS. In addition, structural imaging (MRT) has demonstrated a thinning of the sensorimotor cortex in children and adolescents with GTS. In contrast, an increase in fractional anisotropy as a marker of the directionality of white matter fibers underneath the pre- and postcentral gyrus has been demonstrated in adult GTS patients. These data underscore the role of developmental abnormalities and reorganisation in the somatosensory system in GTS warranting further studies. Multimodal studies including structural and functional imaging and electrophysiology in clinically well characterized GTS subgroups might foster a better understanding of somatosensory phenomena and the role of sensorimotor circuits in GTS.