Diffusion tensor imaging in blepharospasm and blepharospasm-oromandibular dystonia

Patterns of white matter (WM) abnormalities and correlation with clinical features in patients with blepharospasm (BSP) and patients with blepharospasm-oromandibular dystonia (BOM) remain unknown. Using voxel-based analysis, diffusion behaviors of WM including fractional anisotropy (FA), mean diffusivity (MD) and eigenvalues were compared between 20 BSP patients vs. 11 healthy controls (HCs) and 11 patients with BOM vs. 11 HCs. Correlation analyses were performed to assess possible association between diffusion behaviors of significantly different areas and clinical measures. Compared with HCs, BSP patients showed significant FA reductions in the left anterior lobe of cerebellum. Significant increases of MD and radial diffusivity (RD) were detected in right lentiform nucleus and thalamus. Significantly decreased FA in the right precuneus of parietal lobe, increased MD in the right lentiform nucleus and insula, and increased axial diffusivity in the right insula were observed in BOM patients. The FA values in the WM of left cerebellum negatively correlated with disease severity in BSP patients measured by JRS (r = -0.655, p = 0.002). The FA values in the right parietal WM negatively correlated with disease duration in BOM patients (r = -0.745, p = 0.008). Both BSP and BOM are related to microstructural abnormalities of WM in the basal ganglia. WM changes outside the basal ganglia may present trait features that are specific for individual dystonia phenotype. The correlation between FA abnormalities and symptom severity suggests that DTI parameters might be of clinical value in assessing and following disability in BSP patients.