[Botulinum toxin type A in the preventive treatment of chronic migraine: experience in a headache center in Argentina].

INTRODUCTION: Chronic migraine (CM) is one of the most disabling neurological diseases, with a marked impact on quality of life and the use of health resources. In Argentina, there is no published real-life data on the use of botulinum toxin type A; onabotulinumtoxinA (onabotA), in chronic migraine. The objective was to describe the clinical outcomes of patients with CM treated with onabotA at a specialized headache center in Argentina. MATERIALS AND METHODS: We conducted a retrospective review of electronic medical records of all patients treated with onabotA between January and December 2021. Data collected included demographics, medication overuse, prior preventive therapies, headache diaries, treatment response, and adverse events. RESULTS: A total of 394 patients were analyzed (91% women; mean age 46 years). Medication overuse was present in 66% (n=241). Forty percent (n=160) reported end-of-dose deterioration. Adverse events were reported by 4% (n=15), none requiring discontinuation. Among the 162 patients who completed headache diaries, 65% achieved ≥50% reduction in monthly headache days, and 34% reversed medication overuse. CONCLUSION: OnabotA was safe, well tolerated, and effective in reducing headache frequency and medication overuse in CM patients. Our findings are consistent with pivotal trials and real-world studies and represent the first published experience in Argentina.