Long-term outcome of flexible onabotulinum toxin A treatment in facial dystonia

PURPOSE: The purpose of this study was to assess the long-term outcome of onabotulinum used to treat facial dystonia and compare a flexible and fixed treatment regimen. METHODS: This was a retrospective comparative study looking at benign essential blepharospasm (BEB), hemifacial spasm (HFS) and aberrant facial nerve regeneration synkinesis (AFR) treatment with onabotulinum toxin A (Botox®) over a minimum of 10 years. Fifty-one patients were recruited into the study, with each dystonia subgroup having 17 patients. Blepharospasm disability score (BDS), subjective improvement score (SIS), duration of maximal effect (DME) and complications were recorded at each visit. RESULTS: The mean age was 63 years and gender predominately female. Thirty-seven patients underwent flexible treatment intervals compared to 14 fixed treatment intervals, averaging 3.4 and 4 per annum, respectively. Mean BDS significantly improved from 6 to 3 at last review across all 3 groups, with the highest effect on BEB. BDS improvement was greater in flexible intervals. SIS remained similar for all three conditions during follow-up, but in those undergoing flexible intervals, SIS increased by a small margin compared to fixed interval. Mean DME was 10.5 weeks across all dystonias, but increased progressively only in the flexible interval group. Complications included ptosis (30%), dry eye (14%) and lagophthalmos (8%). CONCLUSION: Flexible onabotulinum provided better long-term relief on BDS for facial dystonia than a fixed regimen. Flexible interval treatment may also provide better patient satisfaction and longer DME compared to fixed treatment. Both have similar complication rates. With flexible treatment however, fewer injections were required over 10 years, leading to cost saving.