Neuropathology of blepharospasm

Background: The dystonias are a group of disorders characterized by excessive muscle contractions leading to abnormal repetitive movements or postures. In blepharospasm, the face is affected, leading to excessive eye blinking and spasms of muscles around the eyes. The pathogenesis of blepharospasm is not well understood, but several imaging studies have implied subtle structural defects in several brain regions, including the cerebellum. Objective: To delineate cerebellar pathology in brains collected at autopsy from 7 human subjects with blepharospasm and 9 matched controls. Methods: Sections from 3 cerebellar regions were sampled and processed using Nissl and silver impregnation stains. Purkinje neurons were the focus of the evaluation, along with as several other subtle pathological features of cerebellar dysfunction such as Purkinje neuron axonal swellings (torpedo bodies), proliferation of basket cell processes around Purkinje neurons (hairy baskets), empty baskets (missing Purkinje neurons), and displacement of cell soma from their usual location (ectopic Purkinje neurons). Results: The results revealed a significant reduction in Purkinje neuron and torpedo body density, but no changes in any of the other measures. Conclusions: These findings demonstrate subtle neuropathological changes similar to those reported for subjects with cervical dystonia. These findings may underly some of the subtle imaging changes reported for blepharospasm.