Blepharospasm is a focal dystonia of the orbicularis oculi resulting in repeated involuntary forced eyelid closure, with failure of voluntary opening. It may be sufficiently severe to result in functional blindness. The condition typically begins in the sixth decade of life, and is commoner in women than men. Blepharospasm may occur in isolation or in combination with other involuntary movements which may be dystonic (orobuccolingual dystonia or Meige syndrome; limb dystonia) or dyspraxic (eyelid apraxia).
Blepharospasm is usually idiopathic but may be associated with lesions (usually infarction) of the rostral brainstem, diencephalon, and striatum; it has been occasionally reported with thalamic lesions. The pathophysiological mechanisms underlying blepharospasm are not understood, but may reflect dopaminergic pathway disruption causing disinhibition of brainstem reflexes.
Local injections of botulinum toxin into orbicularis oculi are the treatment of choice, the majority of patients deriving benefit and requesting further injection. Failure to respond to botulinum toxin may be due to concurrent eyelid apraxia or dopaminergic therapy with levodopa.
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