This type of headache is classified as a trigeminal autonomic cephalalgia (TAC). There are 4 types of TACs, and paroxysmal hemicrania is one of them. Paroxysmal hemicrania is characterized by attacks of severe unilateral (one-sided) orbital (around the eye), supraorbital (above the eye), and/or temporal pain lasting 2 to 30 minutes. There must be at least 1 autonomic sign or symptom on the side of the headache [lacrimation (runniness/tearing of the eye), conjunctival injection (redness of the eye), facial sweating or flushing (skin turning blushed), nasal congestion, rhinorrhea (runniness of nose), sense of ear fullness, eyelid edema (swelling), or partial Horner’s syndrome (miosis (pupil becomes small)) and/or ptosis (droopiness of the eye)]. The attacks have a frequency of more than 5 per day for more than 50% of the time when the disorder is active. Chronic paroxysmal hemicrania continua is defined by attacks occurring for more than 1 year without remission, or with remission periods lasting less than 1 month.
To make the full diagnosis, the patient must respond completely to a therapeutic trial of indomethacin (a specific anti-inflammatory (NSAID) medication), used in a very specific way (“Indomethacin trial”). For this reason, this headache is 1 of 2 types of “Indomethacin-sensitive” headaches because Indomethacin is typically the only thing that works. The diagnosis of paroxysmal hemicrania is confirmed by the headache completely stopping after reaching a specific dose of Indomethacin.