A cluster headache is a relatively rare type of headache that affects less than 0.5 percent of the population. Unlike a migraine, it is more common in men than women, although the proportion of women diagnosed with cluster headache has risen over the past 20 years. The headaches can start at any age and often begin in the 20s or 30s.
Most patients with cluster headaches are smokers or ex-smokers. Cluster headaches are unique for their location, associated features, and periodicity.
Cluster headaches got their name because they come in “clusters.” They tend to occur daily for weeks to months at a time and then disappear for a month or more (termed “episodic cluster headache”). They are often seasonal. About 10 to 20 percent of patients have chronic cluster headaches that are continuous from their onset or have remission periods of less than one month.
The attacks usually occur like clockwork and they often awaken people from sleep at the same time each night. Most people experience more than one attack each day, often in the late afternoon or in the evening.
Cluster headache pain comes on quickly and usually without a warning. The pain is located around the eye and temple but can extend to the jaw, cheek, teeth, nose, and side of the head. In most patients, the attacks are always on the same side of the head during a cluster period. The pain is excruciating, boring, stabbing, knifelike, or burning. It is one of the most painful conditions experienced by humans and is sometimes called “suicide headache.”
The signature feature of the attack is the “autonomic symptoms,” which are involuntary and caused by activity of specific nerves in the brain and head. They include a droopy eyelid, a small pupil, eyelid swelling, tearing, bloodshot eye, stuffy or runny nose, flushing, or sweating on the same side as the pain.
Some patients with cluster headache also have symptoms that are more typical of migraine, such as aura, sensitivity to light or noise, nausea, vomiting, or other vague symptoms prior to an attack (mood changes, yawning, food cravings).
Alcohol, odors (solvents, perfume), and sleep are common triggers of cluster headaches. Some patients have other triggers, such as smoking or eating certain foods (similar to migraine triggers).
Most patients experience agitation or become restless during a cluster headache and prefer to pace, rock back and forth, go outdoors, or strike their head to distract themselves from the pain. Others prefer to sit still; it is uncommon to want to lie down during an attack. The attack can last from 15 minutes to three hours.
The diagnosis is based on a typical history and normal neurological examination. Rarely, brain abnormalities (such as a tumor of the pituitary gland) can cause headaches that are very similar to cluster headaches. Brain imaging is recommended for all patients with cluster headaches.
Cluster headache seems to be a lifelong condition in most patients, although remission periods tend to get longer with age. A small percentage of patients with episodic cluster headache evolve into having chronic cluster headache.