Botulinum toxin: evidence-based medicine criteria in blepharospasm and hemifacial spasm.

Botulinum A toxin is recognized and approved for symptomatic treatment of hemifacial spasm and blepharospasm. The state of trials is good, although double-blind placebo-controlled studies have been carried out involving only a small number of cases. Open case control studies have been done with large patient collectives. In both indications, treatment with botulinum toxin reaches the highest EBM degree in a critical evaluation.