Botulinum toxin type A wear-off phenomenon in chronic migraine patients: how long does the maximum efficiency last?

ABSTRACT Background: Botulinum toxin Type A (BoNTA) is a successful treatment for chronic migraine prophylaxis. Objective: We aimed to evaluate the monthly change of effectiveness of BoNTA treatment. Methods: A total of 80 patients (70 females and 10 males) with chronic migraine were included. In our study protocol, we applied to 155 U across 31 fixed-sites and if the patient had pain, 40 U dose injections were applied across 8 specific head/neck muscle areas. Headache days and analgesic intake were noted before the BoNTA injection and during the interviews at the first, second, and third months after the BoNTA injection. Results: The mean age was 37.59 ± 7.60 and 87.5% of the patients were female. The mean number of headache days/month before BoNTA was 18.95±2.69, decreasing to 10.55±3.15 days/month in the first month (p