Background: Primary blepharospasm is a focal dystonia characterised by excessive involuntary closure of the eyelids. The pathophysiology of primary blepharospasm is unresolved.
Aim: To pinpoint grey-matter changes that are associated with primary blepharospasm.
Methods: 16 right-handed patients with primary blepharospasm (mean age 67.4 (SD 4.3) years; 12 women) were compared with 16 healthy volunteers matched for sex and age. High-resolution T1-weighted magnetic resonance imaging of each participant was obtained and analysed by voxel-based morphometry, a method to detect regionally specific differences in grey matter between patients and control group. To evaluate whether the identified grey-matter changes were correlated with the duration of primary blepharospasm or botulinum neurotoxin treatment (BoNT), separate regression analyses were carried out.
Results: In patients with primary blepharospasm, grey-matter increase in the putamina was observed, whereas regression analyses did not indicate a correlation between grey-matter increases and the duration of primary blepharospasm or BoNT. Grey-matter decrease was detected in the left inferior parietal lobule; here regression analyses of grey-matter decrease showed a significant (p = 0.013) correlation of grey-matter decrease with the duration of BoNT.
Conclusions: The data suggest structural changes in primary blepharospasm and point to a crucial role of the putamen for the pathophysiology of this focal dystonia.
- BoNT, botulinum neurotoxin treatment
- FDG, 18F-deoxyglucose
- fMRI, functional magnetic resonance imaging
- VBM, voxel-based morphometry
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Published Online First 11 May 2006
Competing interests: None declared.
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