Cortical gray matter changes in primary blepharospasm: a voxel-based morphometry study

Previous voxel-based morphometry studies of patients with primary blepharospasm documented gray matter volumetric differences of the striatum, cerebellum, thalamus, and parietal lobe areas. However, these results were inconsistent across studies, which recruited relatively small samples and did not always provide detailed clinical information on patients with blepharospasm. The objective of this study was to analyze whole-brain gray matter volume in a larger sample of patients with blepharospasm and to expand on previous works by evaluating whether clinical features of blepharospasm correlate to whole-brain gray matter changes. Voxel-based morphometry was performed on 25 patients with primary adult-onset blepharospasm and 24 healthy subjects (controls) matched for age, sex, and handedness. Clinical data were collected through a standardized interview. Severity of blepharospasm was measured using the Jankovic Rating Scale. Patients with blepharospasm had greater gray matter volume than controls in the right middle frontal gyrus, whereas patients with blepharospasm had smaller gray matter volume than controls in the left postcentral gyrus and left superior temporal gyrus. Spearman correlation analysis with Bonferroni correction failed to show significant correlations between gray matter volume and the explored clinical variables, comprising age at onset, disease duration, blepharospasm severity, presence of an effective geste antagoniste, and dose and duration of botulinum toxin treatment. Patients with blepharospasm exhibited gray matter volume differences exclusively in cortical regions highly relevant to sensory processing and cognitive modulation of motor behavior. Gray matter changes in the primary sensory cortex may represent a common trait of primary dystonias, including blepharospasm.