Cluster headache refers to the characteristic grouping or clustering of attacks. Cluster headaches may also be known as histamine headache, red migraine, Horton’s headache, and cephalalgia or sphenopalatine neuralgia. The headache periods can last several weeks or months, and then disappear completely for months or years leaving considerable amounts of pain-free intervals between series.
Cluster is one of the least common types of headache, and the cause is unknown. Cluster headaches occur more often in men than women. The pain is vascular in nature, and caused by blood vessel swelling in the head. The autonomic nervous system is intimately involved in the genesis of cluster headache and it appears to be mediated by alterations in the hypothalamic area. This area and adjacent areas are believed to regulate both daily as well as yearly cycles that go on in the body. Although it is rare, it is possible for someone with cluster headache to also suffer from migraine headache.
Cluster headache starts suddenly, and a minimal warning of the oncoming headache may occur, including a feeling of discomfort or a mild one-sided burning sensation. This pain is of short duration, generally 30 to 45 minutes. However, the headache itself may last anywhere from a few minutes to several hours and will disappear only to recur later that day. Most sufferers get one to four headaches per day during a cluster period. They occur regularly, generally at the same time each day. Cluster headaches often awaken the sufferer in the early morning or during the night and have been called “alarm clock headaches.”
Typical cluster headache characteristics include:
Pain almost always one-sided
Pain remains on the same side during a series
Pain can occur on the opposite side when a new series starts
Pain is localized behind the eye or in the eye region and may radiate to the forehead, temple, nose, cheek or upper gum on the affected side
The affected eyelid may become swollen or droop and the pupil may contract
The nostril on the affected side of the head is often congested
Nasal discharge and tearing of the eye is on the same side as the pain
Face may become flushed on the affected side
Cluster headaches are not associated with the gastrointestinal disturbances or sensitivity to light that is found in migraine.
The pain of cluster headache is generally intense and severe and often described as a burning or piercing sensation. It may be throbbing or constant, the scalp may be tender and the arteries often can be felt increasing their pulsation. The pain is so intense that most sufferers cannot sit still and will often pace during an acute attack. The cluster headache sufferer has a considerable amount of pain-free intervals between series. Sufferers are generally affected in the spring or autumn, and, due to their seasonal nature, cluster headaches are often mistakenly associated with allergies or business stress. The seasonal relationship is individual for each sufferer.
Substances that cause blood vessel swelling can provoke an acute attack during a series period. Nitroglycerin or histamine, smoking or minimal amounts of alcohol can precipitate or increase the severity of the attacks as the sufferer’s blood vessels seem to change and become susceptible to the action of these substances. The blood vessels are not sensitive to these substances during headache-free periods. Hormonal influences in women do not appear to be a factor in cluster headaches.
Some patients will note that the series of headaches is continuous, not separated by periods of remission. About 20% of cluster sufferers’ attacks are chronic, occurring throughout the year, thus making the control of these headaches more difficult. These chronic cluster headaches differ from episodic cluster headaches as the periods are continuous, and the patients do not respond to conventional forms of cluster therapy.