Background: Although botulinum neurotoxin A has been used for many years to treat focal dystonia-like blepharospasm (BLSP), cervical dystonia (CD), and hemifacial spasm (HFS) as vascular compression disorder of the facial nerve, there are few data on its long-term efficacy.
Methods: We analysed dosages and injection intervals in a group of 130 patients with various focal dystonias treated for 6-16 years.
Results: During the observation period from 2000 to 2006, the mean dosage required to obtain appropriate clinical benefit increased only slightly in BLSP and HSF. In CD however, significantly higher doses were necessary for good clinical results. The mean intervals between injection varied highly between individual patients but did not change significantly between 2000 and 2006. Adverse effects, mostly minor, were reported in 4.2% of all treatment cycles in HSF; the frequencies were 3.8 for BLSP and 2.9 for CD, respectively. None of the patients stopped treatment because of resistance due to antibodies.
Conclusion: Botulinum neurotoxin A is effective in long-term treatment of focal dystonia when injection intervals and dosages are chosen carefully.