ICHD classification and diagnosis of migraine are further subdivided. Overall ICHD-3 beta distinguishes 29 migraine subtypes. The following table outlines the main subtypes and their ICHD-1, -2, -3 beta and ICD-10 codes. Migraine without aura also referred to as a "common migraine", (previously known as "hemicrania simplex") is a specific neurological disorder characterized by recurrent, throbbing headaches that often affect one side of the head (i.e., it is unilateral), are of at least moderate intensity, and may cause nausea, phonophobia or photophobia. One defining characteristic of the common migraine is a lack of the visual disturbances known as an aura. The exact International Classification of Headache
Hemicrania continua Hemicrania continua Hemicrania continua (HC) is a persistent unilateral headache that responds to indomethacin. It is usually unremitting, but rare cases of remission have been documented. Hemicrania continua is considered a primary headache disorder, meaning that it is not caused by another condition. The International Headache Society's International Classification of Headache Disorders classifies hemicrania continua as a primary headache disorder. The following diagnostic criteria are given for hemicrania continua: A variant on hemicrania continua has also been described, in which the attacks may shift sides, although meeting the above criteria in all other respects. Main features differentiating CPH from cluster