Onabotulinumtoxin A for chronic migraine with medication overuse: clinical results of a long-term treatment.

The use of Onabotulinumtoxin A as treatment for different neurological conditions is more common in the last decades; its application has been consolidated on the basis of significant clinical results. The clinical experiences with Onabotulinumtoxin A for chronic migraine are on the increase in Italy: at the moment, clinical results are encouraging and enforce the application of the toxin for chronic migraine, according to the results of the PREEMPT studies. The possibility for the patients to be treated with a second cycle of therapy after the first year of treatment is under discussion, in particular for patients who obtained significant clinical benefit from the first period of treatment. In this report, a group of patients treated with Onabotulinumtoxin A for 1 year, according to the PREEMPT protocol, has been retreated for one more year in order to confirm the clinical benefit obtained after the first year of treatment.