Long-term efficacy of botulinum a toxin for blepharospasm and hemifacial spasm

To determine whether the duration of relief from symptoms in patients with essential blepharospasm (EB) or hemifacial spasm (HFS) who receive serial treatments with botulinum toxin type A (BtA) changes over the long-term.

Retrospective longitudinal comparative analysis. The main outcome measure is the mean duration of relief from symptoms after an injection with BtA. Participants included 34 patients who received 30 or more serial BtA treatments for facial dyskinesia (EB or HFS). Repeated measures and linear regression analyses were used to determine trends and the mean duration of relief from symptoms was compared between early (first ten effective treatments) and late (last ten treatments) sessions in each group.

In the EB group (18 patients), the mean duration of relief was 13.5 weeks for the early and 11.4 weeks for the late sessions (P = 0.04). In the HFS group (16 patients) the mean duration of relief was 12.4 weeks in both treatment periods (P = 0.91). The duration of relief had a small negative correlation with mean late session BtA dose in the EB group (P = 0.03) but no correlation in the HFS group (P = 0.12).

There was a trend towards a decreased duration of relief from symptoms in patients with EB over the long-term, but no changes for HFS. The treatment remains effective in relieving symptoms and signs for both conditions.