Neuroanatomy of coprolalia in Tourette syndrome using functional magnetic resonance imaging

Objective: To determine the neural substrates of phonic tics in Tourette syndrome (TS) using functional magnetic resonance imaging (fMRI) and compare with a proposed tic-generating network (TGN). Patients: One with TS and one normal control. Methods: fMRI scans were obtained on the TS patient during which numerous unsuppressed phonic tics occurred and, along with the scanner noise, were recorded on audiotape. The control underwent the same functional MRI sequence but mimicked the tics within predetermined, on-off time blocks. Fuzzy clustering (FC) methods were used to generate the activation maps. Results: The TS patient and control showed fMRI activation in the left middle frontal gyrus and right precentral gyrus. The TS patient also had activity in the caudate nucleus, cingulate gyrus, cuneus, left angular gyrus, left inferior parietal gyrus, and occipital gyri. Conclusions: fMRI, using an FC analysis, is a viable technique for studying TS patients with phonic tics. These results give further support to the hypothesis of a tic-generating circuit model. Further studies are required to confirm our data.