Premonitory urges are associated with decreased grey matter thickness within the insula and sensorimotor cortex in young people with Tourette syndrome

Abstract

Tourette syndrome (TS) is a neurological disorder characterized by vocal and motor tics and is associated with cortical-striatal-thalamic-cortical circuit (CSTC) dysfunction and hyperexcitability of cortical limbic and motor regions, which are thought to lead to the occurrence of tics. Importantly, individuals with TS often report that their tics are preceded by 'premonitory sensory phenomena' (PSP) that are described as uncomfortable cognitive or bodily sensations that precede the execution of a tic, and are experienced as a strong urge for motor discharge. While the precise role played by PSP in the occurrence of tics is controversial, PSP are nonetheless of considerable theoretical and clinical importance in TS, not least because they form the core component in many of the behavioural therapies that are currently used in the treatment of tic disorders. In this study, we investigated the brain structure correlates of PSP. Specifically, we conducted a whole-brain analysis of cortical (grey matter) thickness in 29 children and young adults with TS and investigated the association between grey matter thickness and PSP. We demonstrate for the first time that PSP are inversely associated with grey matter thickness measurements within the insula and sensorimotor cortex. We also demonstrate that grey matter thickness is significantly reduced in these areas in individuals with TS relative to a closely age-and gender-matched group of typically developing individuals and that PSP ratings are significantly correlated with tic severity.

Deep Brain Stimulation for Tourette’s Syndrome: The Case for Targeting the Thalamic Centromedian–Parafascicular Complex

“…Sowell and colleagues (38) and Draper and colleagues (39) observed a cortical thinning in the premotor, motor, somatosensory, insular, and anterior cingulate cortices in TS, the severity of which correlated with severity of tics and premonitory urges. This morphological alteration was more prominent in the ventral portions of the sensory and motor homunculi, and the cortical thinning in this area positively correlated with tic severity in the oro-facial district (38).…”

Neurobiology of the Premonitory Urge in Tourette’s Syndrome: Pathophysiology and Treatment Implications

“…Using a combined structural and spectroscopic magnetic resonance imaging, Puts et al {85} showed that in vivo GABA concentration over the sensorimotor cortex of children with TS is reduced compared with healthy controls, possibly reflecting inhibitory dysfunction of both somatosensory and motor cortex. Finally, a recent study by Draper et al {86} demonstrated that cortical thickness within the insular and sensorimotor cortex was inversely associated with ratings of the strength of premonitory urges in young adults with TS and that cortical thickness within the sensorimotor cortex, anterior cingulate, and insula was significantly reduced relative to a matched group of typically developing controls. These findings of significant cortical thinning within the sensorimotor, insular, and cingulate cortices of patients with TS confirmed similar findings reported by a previous morphometric magnetic resonance imaging study {87}, although it has been highlighted that the cortical thinning findings could also be explained by more frequent small-amplitude head movements during scanning in the TS groups {88}.…”

Functional neuroimaging in Tourette syndrome: recent perspectives

“…16 A more recent study has shown that premonitory urges are associated with a significantly reduced gray matter thickness within the left insula and right sensorimotor cortex. 17 …”

“…Involvement of insula and cingulate cortex 15 2. Gray matter thinning within sensory areas of the frontosubcortical circuitry, 15 within the left insula and right sensorimotor cortex 17 …”