The cerebellum in idiopathic cervical dystonia: A specific pattern of structural abnormalities?

Introduction: In recent years, cerebellar abnormalities have gained increasing attention as possible physiopathological substratum of idiopathic cervical dystonia (ICD), but a consistent pattern of cerebellar structural modifications has not yet been established. We systematically investigated the presence of volumetric alterations of cerebellar gray (GM) and white matter (WM) in ICD patients, as well as their clinical relevance. Methods: In this two-centers prospective cross-sectional study, from May 2013 to December 2017, 27 patients with ICD and 27 age- and sex-comparable healthy controls underwent brain MRI including 3D T1-weighted sequences for volumetric analyses. Between-group differences in terms of gray matter and cerebellar peduncles volumes were investigated using both region of interest (ROI)-based and voxel-based approaches using the SUIT tool (SPM12), and significant volumetric changes were correlated with clinical impairment (as measured with the Tsui score) and presence of tremor. Results: ICD patients showed significant volumetric reduction of cerebellar GM in the anterior lobe and lobule VI, resulting from both ROI-based (p <= 0.009) and voxel-based (p <= 0.04) analyses, while small clusters of reduced WM volume were found in the right cerebellum and left midbrain (p = 0.04), along with reduced volume of the bilateral superior (p = 0.04) and middle (p = 0.03) cerebellar peduncles. Furthermore, higher middle cerebellar peduncles volume was associated with the presence of tremor (p = 0.04). Conclusion: Our data show evidence of a specific pattern of cerebellar structural abnormalities in ICD patients, with volume loss mainly involving cortical GM regions related to the somatotopic representation of the affected body parts and, to a lesser extent, cerebellar peduncles.