Spasmodic Dysphonia Primary Dystonia Is Associated with Cortical and Subcortical Alterations: A Multimodal Imaging Study (P4.325)

OBJECTIVE: To assess the patterns of cortical and subcortical gray matter (GM) and white matter (WM) damage in patients with Spasmodic Dysphonia (SD) primary focal dystonia compared with healthy controls (HC). BACKGROUND: Recent advanced neuroimaging studies showed altered WM integrity of the internal capsule as well as increased GM volume of the laryngeal sensorimotor cortex in SD patients. Further studies are needed to confirm such structural changes associated with the disease. DESIGN/METHODS: T1-weighted and diffusion tensor (DT) MRI scans were obtained from 13 SD patients and 30 HC. TBSS was applied to compare DT MRI indices (i.e., mean [MD], radial [radD] and axial diffusivities, and fractional anisotropy [FA]) between groups on a voxel-by-voxel basis. GM cortical measures were analyzed using surface-based morphometry. FMRIB-FIRST tool in FSL was used to segment basal ganglia on T1-weighted images, and volumes and DT MRI metrics of GM nuclei were measured. RESULTS: Compared with controls, SD patients showed increased MD, radD and decreased FA of the corpus callosum and major WM tracts, mainly in the right hemisphere. Cortical surface analysis showed that SD patients compared to HC had cortical volume increase of the left postcentral, supramarginal and fusiform gyri, while a widespread cortical volume and area decrease was found in the right hemisphere, involving pre- and postcentral gyri and frontal and parietal lobes. SD patients compared to controls did not show significant differences in the basal ganglia volumes, while altered DT MRI metrics were found in right caudate, pallidum and putamen. CONCLUSIONS: Structural alterations in SD patients seem to involve both GM and WM, with different patterns in right and left hemisphere. Such changes may suggest a complex network disorder underlying the pathophysiology of the disease. Advanced neuroimaging studies may give further insight into the understanding of this complex disorder.