Blepharospasm associated with olivopontocerebellar atrophy.

We report two cases of cranial dystonia (blepharospasm) associated with olivopontocerebellar atrophy (OPCA). The pathophysiology of blepharospasm appears to involve an increased excitability of the interneurons of the blink and corneal reflexes. It is hypothesized that blepharospasm associated with OPCA might be due to rostral brainstem lesions disrupting central dopaminergic and cholinergic pathways, resulting in disinhibition of brainstem reflexes or denervation supersensitivity of the facial nuclear complex.