The term "cluster headache" refers to a type of headache that recurs over a period of time. People who have cluster headaches experience an episode one to three times per day during a period of time (the cluster period), which may last from 2 weeks to 3 months. The headaches may disappear completely (go into "remission") for months or years, only to recur. A cluster headache typically awakens a person from sleep 1 to 2 hours after going to bed. These nocturnal attacks can be more severe than the daytime attacks. Attacks appear to be linked to the circadian (or "biological") clock. Most people with cluster headaches will develop cluster periods at the same time each year -- either in the spring or fall or the winter or summer.
Cluster headaches are one of the most severe types of headache. It can be 100 times more intense than a migraine attack.
Who Gets Cluster Headaches?
Cluster headaches are the least common type of headaches, affecting less than 1 in 1,000 people. Cluster headaches are a young person's disease: the headaches typically start before age 30. Cluster headaches are more common in men, but more women are starting to be diagnosed with this problem. The male to female ratio is 2-3:1.
Causes
The true biochemical cause of cluster headaches is unknown. However, the headaches occur when a nerve pathway in the base of the brain (the trigeminal-autonomic reflex pathway) is activated. The trigeminal nerve is the main nerve of the face responsible for sensations (such as heat or pain.)
When activated, the trigeminal nerve causes the eye pain associated with cluster headaches. The trigeminal nerve also stimulates another group of nerves that causes the eye tearing and redness, nasal congestion and discharge associated with cluster attacks.
The activation of the trigeminal nerve appears to come from a deeper part of the brain called the hypothalamus. The hypothalamus is home to our "internal biologic clock" which regulates our sleep and wake cycles on a 24-hour schedule. Recent imaging studies have shown activation or stimulation of the hypothalamus during a cluster attack.
Cluster headaches usually are not caused by an underlying brain condition such as a tumor or aneurysm.
Triggers
The season is the most common trigger for cluster headaches, which often occur in the spring or autumn. Due to their seasonal nature, cluster headaches are often mistakenly associated with allergies or business stress. The seasonal nature of cluster headaches most likely results from stimulation or activation of the hypothalamus (see above).
Cluster headaches are also common in people who smoke and drink alcohol frequently. During a cluster period, the sufferer is more sensitive to the action of alcohol and nicotine, and minimal amounts of alcohol can trigger the headaches. During headache-free periods the person can consume alcohol without provoking a headache.
Symptoms
Cluster headaches generally reach their full force within five or ten minutes after onset. The attacks are usually very similar, varying only slightly from one attack to another.
Type of Pain: The pain of cluster headache is almost always one-sided, and during a headache period, the pain remains on the same side. When a new headache period starts, it rarely occurs on the opposite side.
Severity/Intensity of Pain: The pain of a cluster headache is generally very intense and severe and is often described as having a burning or piercing quality. It may be throbbing or constant. The pain is so intense that most cluster headache sufferers cannot sit still and will often pace during an attack.
Location of Pain: The pain is located behind one eye or in the eye region, without changing sides. It may radiate to the forehead, temple, nose, cheek, or upper gum on the affected side. The scalp may be tender, and the pulsing in the arteries often can be felt.
Duration of Pain: The pain of a cluster headache lasts a short time, generally 30 to 90 minutes. It may, however, last from 15 minutes to three hours. The headache will disappear only to recur later that day. Typically, in between attacks, people with cluster headaches are headache free.
Frequency of Headaches: Most sufferers get one to three headaches per day during a cluster period (the time when the headache sufferer is experiencing daily attacks). They occur very regularly, generally at the same time each day, and have been called "alarm clock headaches" because they often awaken the person at the same time during the night.
Most cluster sufferers (80%-90%) have episodic cluster headaches that occur in periods lasting seven days to one year, separated by pain-free episodes lasting 14 days or more.
In about 20% of people with cluster headaches, the attacks may be chronic, meaning there are less than 14 headache-free days per year. Chronic cluster headaches vary from episodic cluster headaches, as they are continuous without remission periods.
Cluster headaches are not typically associated with nausea or vomiting. It is possible for someone with cluster headaches to also suffer from migraines.
Is There Any Way to Tell That a Cluster Headache Is Coming?
Although the pain of a cluster headache starts suddenly, there may be a few subtle signs of the oncoming headache. Some signs include:
Feeling of discomfort or a mild, one-sided burning sensation.
The eye on the side of the headache may become swollen or droop. The pupil of the eye may get smaller and the conjunctiva (the pink tissue that lines the inside of the eyelid) will redden.
Nasal discharge. There may be nasal discharge or congestion and tearing of the eye during an attack, which occur on the same side as the pain.
Excessive sweating.
Flushing of the face on the affected side.
Light sensitivity.
Treatment
Abortive medications: The most successful treatments are Imitrex (sumatriptan) injections and breathing oxygen through a face mask for twenty minutes. Other choices include: Zomig (zolmitriptan) tablets, ergotamine drugs and intranasal lidocaine.
Preventive medications: Your doctor can prescribe preventive medications to shorten the length of the cluster headache period as well as decrease the severity of the headaches. All cluster headache sufferers should take preventive medication unless their cluster periods last less than two weeks. Some medications used in the prevention of cluster headaches include: calcium channel blockers (verapamil), lithium, divalproex sodium, corticosteroids (only short courses), methysergide, melatonin and Topamax.
Surgery: This may be an option for people with chronic cluster headaches who have not been helped with standard therapy. Most of the procedures involve blocking the trigeminal nerve.
All of these treatments should be used under the direction of a doctor familiar with treating cluster headaches. As with any medication, it is important to carefully follow the label instructions and your doctor's advice.
