RESUMEN
PURPOSE: To report the clinical success and incidence of adverse events of repetitive botulinum toxin treatment of 15 years or greater. DESIGN: Retrospective cohort study. METHODS: The study sample consisted of 37 patients from a clinical practice, 11 male and 26 female. Inclusion criteria consisted of patients treated a minimum of 15 consecutive years for facial dystonia. Seven patients had hemifacial spasm, 4 Meige syndrome, and 26 benign essential blepharospasm. Main outcome measures consisted of treatment efficacy and adverse events. RESULTS: Mean treatment duration was 19.4 years (SD 2.2) with an average of 62 (SD 22) treatments of 70.2 (SD 20.8) neurotoxin units. Mean duration of treatment efficacy was 127 days (SD 37) with a 5% physician-reported minor adverse event rate and no major adverse events over each patient's clinical course. Patients reported no major and 20% incidence of minor adverse events over the treatment course. CONCLUSION: Results suggest that long-term botulinum toxin treatment produces clinical success in the alleviation of facial dystonia symptoms. Treatment produced a low incidence of major adverse events and minor adverse events. Previous studies may under-report clinical success and over-report adverse events because of study design.