OnabotulinumtoxinA (Botox) in chronic migraine with and without medication overuse

Chronic Migraine (CM) is one of the most disabling primary headache disorders affecting 2% of general population. CM is defined as headaches on >15 days per month for >3 months of which >8 days fulfill the criteria for migraine with or without aura or relieved by migrainespecific treatment [1].CM has an important economic and social impact compared with episodic migraine [2]. CM patients require preventative treatment taken on a daily basis and acute treatment during migraine attacks. Some of the current preventative drugs (beta-blockers and antidepressants) are low-priced and generic and do not have randomized controlled trial to support their efficacy in CM. The only oral medication with some evidence of efficacy in CM is Topiramate [3,4]. Other treatments such as greater occipital nerve block and occipital nerve stimulator are invasive and have limitations [5].