[Onabotulinumtoxin A in the treatment of chronic migraine]

INTRODUCTION. Chronic migraine is the most frequent complication of migraine. Its management is complex and difficult, and is based essentially on preventive measures. AIM. To analyse the development of the use of Onabotulinumtoxin A (OnabotA) in migraine, especially in its chronic form, the method of administration, its mechanism of action, its safety profile and its possible indications in clinical practice. DEVELOPMENT. The study conducts a thorough review of all the clinical trials in the literature that have used OnabotA in the prevention of migraine, both in its episodic and its chronic forms, and the outcomes in the chronic form are analysed in detail. CONCLUSIONS. In studies in phase III, OnabotA has proved to be effective in the treatment of patients with chronic migraine, with significant reductions in the mean frequency of days with headaches, the number of headache episodes, the days with migraine or the proportion of patients with severe disability, in addition to other parameters. It is also effective in the subgroup of patients with symptomatic headache due to medication abuse. OnabotA has proved to be safe and well tolerated in this indication, with foreseeable, usually mild or moderate, transitory side effects. In sum, OnabotA is a safe, well-tolerated alternative in the preventive treatment of chronic migraine.