[Chronic migraine: definition, epidemiology, risk factors and treatment]

Chronic migraine is the most frequent complication of migraine. It is defined by the presence of headache on 15 or more days a month, of which at least eight must meet the criteria of migraine without aura for a minimum of three months. In addition they must not be due to medication abuse or attributable to any other cause.The prevalence of chronic migraine ranges between 1-3% of the population and its incidence has been estimated to be 2.5% per year. It produces from four to six times more disability, decreased productivity and disruption of quality of life than episodic migraine. The development of chronic migraine has been associated with both non-modifiable risk factors (being female, low socio-economic status and level of schooling) and modifiable risk factors (anxiety, depression, sleep apnoea/snoring, obesity, consumption of painkillers and caffeine). Patients with chronic migraine suffer from chronic pain, anxiety or depression two to three times more often than those with episodic migraine. Management requires identification and control of the risk factors that predispose patients to develop the condition, detoxification therapy in the event of abuse of analgesics, specific treatment for migraine attacks and preventive treatment. The effectiveness of the preventive drugs topiramate and Onabotulinumtoxin A in this complication of migraine has been proved in large-scale placebo-controlled clinical trials.Chronic migraine is a common condition that requires global management aimed at reducing the frequency of the attacks, lowering the associated disability and improving the patients' quality of life.