Botulinum toxin A treatment for primary hemifacial spasm: a 10-year multicenter study.

Background: Botulinum toxin A (BTX) is the currently preferred symptomatic treatment for primary hemifacial spasm (HFS), but its long-term efficacy and safety are not known.

Objective: To assess the long-term effectiveness and safety of BTX in the treatment of primary HFS.

Design: Retrospective review of medical records of the 1st and 10th years of treatment.