Botox converts chronic migraines into episodic in 70% of patients

Botox (anabotulinumtoxinA) is the only treatment approved by the FDA for the treatment of chronic migraine headaches. The FDA based its approval on the results of two clinical trials with 700 patients in each (I participated in one of them). In these studies half of the patients were given placebo injections and the other half, Botox for the first six months and then everyone was getting Botox. Even after 4 weeks following the first treatment those who received Botox were doing better than those who received placebo. After the first Botox treatment 49% of participants had a 50% reduction in the number of headache days, after the second treatment this number was 60% and after the thurs, 70%. After 56 weeks, 70% of patients treated with Botox continued to have at least a 50% improvement in headache days per month. This means that by that time 70% of patients were no longer were having chronic migraine, which is defined as having a headache on more than half of the days. So, even in those chronic migraine sufferers who were having daily headaches, a 51% improvement meant that they no longer had headaches on more than half of the days. This also means that Botox converts chronic migraine into episodic. My observation over 18 years of injecting Botox for headaches also indicates that with continued treatment some people stop having migraines altogether. Of course, this observation does not mean that Botox was definitely the reason why headaches stopped since migraines often subside with age and at times can stop without an obvious reason on their own. However, the fact that improvement occurs gradually and continuously with repeated Botox injections suggests that Botox does contribute to this complete resolution of headaches.
Another point I would like to emphasize that some patients who did not a significant improvement after the first treatment did improve after the second or even third. Most of my colleagues and I will not do a third treatment if the first two were completely ineffective. However, if even mild improvement occurs, it may be worth repeating the treatment.