Botulinum Toxin for the Treatment of Chronic Migraines

Migraines are the third most common disease in the world, with an estimated global prevalence of 14.7%. Migraine has a characteristic throbbing quality, of moderate to severe intensity, generally unilateral, and has associated symptoms including photophobia, phonophobia, and gastrointestinal distress. Episodic migraine occurs less than 15 days per month, while chronic migraines occur more or equal to 15 days per month. Treatment of migraine consists of abortive and preventive therapy. Acetaminophen, aspirin, and NSAIDs are often used for management of mild attacks. For more severe attacks, trip - tans are recommended. Intravenous administration of some combination of dopamine receptor agonists, dihydroergotamine, and intravenous NSAIDs is recommended for severe episodes. Preventive daily treatment of migraine is recommended when migraine episodes exceed 6–8 days per month, or what is tolerable to the patient. Beta-blockers, topiramate, amitriptyline, and divalproex sodium are commonly used for migraine prevention. Initial anecdotal reports in patients receiving botulinum toxin for facial cosmetic purposes noted the effects of these injections on headache and trigger point-initiated pain syndromes, which appeared to be independent of its effects upon muscle tone. Current thinking is that migraine pain results from activation of intracranial meningeal perivascu lar afferents with some studies suggesting the role of extracranial afferents.