The present invention is directed to a modified botulinum neurotoxin A (BoNT/A) for use in treating a facial dystonia, including blepharospasm and hemifacial spasm, wherein the unit dose of the modified BoNT/A is greater than 240 pg (or greater than 8000 pg) of modified BoNT/A, wherein the modified BoNT/A is administered by intramuscular injection to an affected muscle of a subject, wherein the total dose administered during the treatment is greater than 24,000 pg (or greater than 82500 pg) and up to 264,000 pg (e.g. up to 240,000 pg) of the modified BoNT/A, and wherein the modified BoNT/A comprises a BoNT/A light-chain and translocation domain (HN), and a BoNT/B receptor binding domain (HC domain).