Bilateral enlargement of the putamen may reflect dopaminergic dysfunction or neuroimmunologic alterations (PANDAS) underlying Tourette syndrome. The larger callosal motor subregion 3 might be a consequence of daily tic activity. Previous divergent volumetric findings might be ascribed to confounding variables like comorbid conditions or medication, or to different imaging methods.

Morphometric findings in Tourette's syndrome (TS) are still inconsistent probably due to differences in analysis approaches as well as several confounders (coexisting psychiatric conditions, medication status, etc.). Our aim was to identify possible morphometric changes in a well-defined sample of drug-naïve boys with "pure" TS. High-resolution structural magnetic resonance images of 38 boys with TS were compared with those of 38 healthy boys matched for age and IQ using voxel-based morphometry (VBM). Coexisting psychiatric conditions and previous medication were excluded. The inclusion of 10- to 15-year-old boys minimized the well known compensatory changes due to tic suppression over many years. VBM analyses revealed no differences between the treatment naïve boys with "pure" TS and healthy controls. Brain morphology is not altered in boys with "pure" TS. Further studies should reveal whether previous findings might be ascribed to confounding factors like coexisting psychiatric conditions or long-term compensatory mechanisms due to voluntary tic suppression.