MRI morphometry in primary focal dystonia

Abstract

Primary blepharospasm (BS) is one of most frequent forms of focal dystonia characterized by excessive involuntary eye closure. Pathophysiology of primary BS remains obscure. The purpose of this study: to determine changes of the cerebral gray matter volume that may be pathogenically important in primary BS. We examined 23 right-handed patients with primary BS (6 males and 17 females) and 16 healthy age- and sex-matched individuals who underwent voxel-based morphometry (VOM) – a method of assessment of fine regional quantitative changes of gray matter volume. In 15 patients VOM studies were performed twice, before and one month after injections of botulinum toxin type A (BTA). Compared to controls, BS patients were characterized by the decrease in gray matter volume in the head of the right caudate nucleus, anterior and posterior lobes of the right cerebellar hemisphere, and the right fusiform gurus. Multiplefactor analysis did not show relationships between gray matter changes and age of patients, age at the debut of BS, and duration of the disease or BTA treatment. On repeat examination after local BTA injections in the circular orbicular muscles (aimed at reducing dystonic spasms in BS patients), the increase in gray matter volume in both fusiform gyri, the opercular parts of the left Rolandic gyrus, the right middle and the left inferior temporal gyri, the left inferior frontal gyrus, and the left cingular gyrus was observed. The obtained data demonstrate the presence of structural brain changes in primary BS, confirming a significant role of the striatum and the cerebellum in pathophysiology of this form of focal dystonia.