published results of a systematic review and meta-analysis investigating the relationship between PU severity and neuronal correlates. Altogether, 22 studies were identified with a total of 1236 patients. Results of a  meta-regression demonstrated that age and tic severity were related to PU severity. From the neuroanatomic perspective, PU was related to the following brain regions:  insula, prefrontal cortex, anterior cingulate cortex, and supplementary motor area.