Chronic migraine is defined as headache on more than 15 days per month in patients with migraine. Chronic migraine is difficult to treat and requires a multidisciplinary approach. Only two pharmacological treatments have been shown to be effective in placebo-controlled randomized trials: topiramate and local injection of botulinum toxin.
The International Headache Society separates primary headaches into episodic and chronic headache. Chronic headache is defined as more than 15 headache days per month for a time period of more than 3 months. Chronic migraine may be complicated by the frequent or regular use of symptomatic treatment with analgesics including opioids or specific migraine drugs (eg, ergots or triptans). This condition is termed chronic migraine with medication overuse. Medication overuse is defined as intake of simple analgesics (eg, aspirin, acetaminophen, or ibuprofen) on more than 15 days per month or the intake of combination analgesics, opioids, ergots, or triptans on more than 10 days per month.