Transcranial sonography of subcortical structures in tic/tourette disorder

Functional neuroimaging studies demonstrate disinhibition of the cortico-striatal-thalamo-cortical circuit. However, structural imaging studies revealed conflicting results, some suggesting smaller volumes of the caudate nucleus (CN) in children with Gilles de la Tourette syndrome (TS). Here we wanted to find out whether transcranial sonography (TCS) detects alterations of raphe nuclei, substantia nigra, lenticular nucleus (LN), or CN in children with Tic disorder or TS (TIC/TS).The study included 25 treatment-naive children (age: 12.2 ± 2.5 years) with a DSM-V based diagnosis of Tic disorder or TS (10 subjects), without other psychiatric or neurologic diagnosis, and 25 healthy controls (age: 12.17 ± 2.57 years), matched for age and sex. Parental rating of behavioral, emotional abnormalities, somatic complaints and social competencies of the participants were assessed using the Child Behavior Check List (CBCL/4-18R). TCS of deep brain structures was conducted through the preauricular acoustic bone windows using a 2.5-MHz phased-array ultrasound system. Fisher's exact test and Mann-Whitney-U test were used for comparisons between TIC/TS patients and healthy volunteers. The number of participants with hyperechogenic area of left CN in the TIC/TS sample was increased, compared to the healthy control group. TIC/TS patients with hyperechogenic CN showed an increased occurrence of thought- and obsessive-compulsive problems. This TCS study revealed pathologic structural changes in CN, its higher occurrence in TIC/TS compared to healthy controls and the relation to comorbidity of thought problems. Further research should focus on the molecular cause of these alterations, probably the disturbed iron metabolism.