Anatomical correlates of blepharospasm

BACKGROUND: Focal dystonia is a neurological disorder characterized by unwanted muscle spasms. Blepharospasm is a focal dystonia producing an involuntary closure of the eyelid. Its etiology is unknown. OBJECTIVE: To investigate if there are structural changes in the white and grey matter of blepharospasm patients, and if the changes are related to disease features. METHODS: T1 and diffusion-weighted magnetic resonance imaging scans were collected from 14 female blepharospasm patients and 14 healthy matched controls. Grey matter volumes, fractional anisotropy (FA), and mean diffusivity maps were compared between the groups. Based on grey matter differences within the facial portion of the primary motor cortex, the corticobulbar tract was traced and compared between groups. RESULTS: Changes in grey matter in patients included the facial portion of the sensorimotor area and anterior cingulate gyrus. These changes did not correlate with disease duration. Corticobulbar tract volume and peak tract connectivity were decreased in patients compared with controls. There were no significant differences in FA or mean diffusivity between groups. CONCLUSIONS: Grey matter changes within the primary sensorimotor and the anterior cingulate cortices in blepharospasm patients may help explain involuntary eyelid closure and the abnormal sensations often reported in this condition.