Chronic headaches - etiology
According to the National Library of Medicine (NIH) chronic headaches occur in 1-4% of the entire population. It is not defined as a single disease but covers all chronic headaches variants. By International Headache Society definition, chronic daily headaches (CDH) are "15 or more headache episodes per month for at least 3 months." It is important to mention 5 major subtypes of primary and secondary pathology: migraine headache, tension-type headache, medication overuse headache, hemicrania continua, daily persistent headache. Each of those also is classified by duration: fewer than 4 hours- a short headache and more than 4 hours- a long headache. When talking about a long variant, typical features include a unilateral, pulsatile, moderate to severe symptoms with or without an aura. In contrast in children and adolescents it is often bilateral, and associated with photophobia and phonophobia. More in the original article!