Long term results of botulinum toxin type A (Dysport) in the treatment of hemifacial spasm: a report of 175 cases

Objective-To describe the long term efficacy and side effects of the treatment of hemifacial spasm with Dysport and to evaluate two different sites of injection to hopefully reduce side effects. Methods-This study was designed as a prospective descriptive study. Injections were made subcutaneously around the eye. Peak improvement was subjectively assessed by using a visual analogue scale and reported in percentages (0-100%). Duration of improvement was assessed subjectively and reported in months. Results-Of 175 cases, 17 were lost to follow up and were excluded. 855 treatments were injected in the remaining 158 patients with a median of 4 treatments. The response rate was 97%. Of 855 treatments, the adjusted mean peak and duration of improvement was 77.2 (95% confidence interval (95%CI) 74.7-79.4)% and 3.4 (95%CI 3.2-3.6) months respectively.In 158 patients (complete group), the long term results from the first to the 12th treatment showed that the mean peak improvement ranged from 72.70 to 80.10% and the duration of improvement was 2.60 to 3.71 months. It remained constant throughout (p=0.40, p=0.87 respectively). The most common side effect was ptosis. Of the 158 patients, 21 completed 12 treatments (subgroup). A separate analysis of this group disclosed a mean peak and duration of improvement from the first to 12th treatments ranging from 70.00 to 78.10% and 2.65 to 4.31 months respectively. Analysis of variance with repeated measures showed no significant variation of peak and duration of improvement over the first to the 12th treatments (p=0.38, p=0.38 respectively). Only 3% of the treatments were unsuccessful but responded to subsequent treatments. The incidence of ptosis was reduced from 27.17% to 9.68% by moving the injection site to the lateral part of orbital orbicularis oculi without any loss of efficacy. The yearly cost of Dysport is considerably less than Botox. Conclusion-This study is the first to show, in detail, the long term results of treatments of hemifacial spasm with Dysport. The efficacy is constant throughout the first to 12th treatments in both the complete group and subgroup. Ptosis can be reduced by moving the injection site further up to the lateral part of the orbital orbicularis oculi. The efficacy of Dysport is comparable with Botox(R) in long term follow up.