This type of headache is classified as a trigeminal autonomic cephalalgia (TAC). There are 4 types of TACs, and cluster headache is the most common of them. Cluster headache is characterized by attacks of severe unilateral (one-sided) orbital (around the eye), supraorbital (above the eye), and/or temporal pain lasting 15 to 180 minutes if untreated. There is either agitation/restlessness with the headache attack and/or 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)]. Headache attacks typically occur from 1 every other day to 8 per day for more than half the time during a cluster cycle. Chronic cluster headache is defined by attacks that occur for more than 1 year without remission, or with remission periods lasting less than 1 month.
Cluster headache attacks occur in “clusters”, or cycles, of frequent headache attacks. These cycles of cluster attacks may last for weeks or months before they go away completely. Remission periods can last months to years. Cluster cycles often occur at a predictable time of year, such as season changes. At the onset of a cluster cycle, a course of high dosed Prednisone is often started over 1-2 weeks to try to break up or shorten the cycle. Cluster headaches can occur anytime during the day, but classically occur at the same time every night, often waking the patient up from sleep. Men tend to be affected 3 times more than women, but it is seen in both men and women. It is a severely painful headache, and has been termed “suicide headache” at times because of the pain severity.