Cluster Headache: What It Is, Causes, and How It Manifests

Cluster headache is a rare type of headache in which attacks occur in series several times a day for weeks and months. It is not a consequence of another disease, and it differs markedly from migraine. Let us examine the mechanism, symptoms, and signs that call for a doctor.

Cluster Headache: What It Is

Attacks group into clusters — series that last from several weeks to several months. Then the pain suddenly disappears for months, and sometimes for years.

Within a series, an attack recurs daily or almost daily, from one to three times a day, and in rare cases up to ten. A single attack lasts from 15 minutes to 3 hours.

How a Cluster Headache Attack Manifests

The pain is sharp, burning, or piercing, almost always on one side of the head, most often around the eye. It peaks within 5–10 minutes, and the most intense phase lasts from 30 minutes to 2 hours.

The attack begins and ends quickly, without warning signs. The person cannot lie still: they walk, move, and change body position.

Autonomic companions appear on the side of the pain:

• redness and tearing of the eye;
• drooping of the eyelid and swelling around the eye;
• constriction of the pupil on the same side;
• nasal congestion or discharge from the nose;
• facial sweating, flushing, nausea.

The side is usually the same, although in about 15% of patients it changed with new attacks. Attacks often wake the person at night, 2–3 hours after falling asleep.

How Cluster Pain Differs from Migraine

Some symptoms of cluster headache overlap with migraine, and it is easily confused with migraine, sinus, and tension headache. Clinically, however, it differs from migraine.

Cluster headache has its own features: during an attack the person is restless and wants to move, the pain begins and ends quickly, lasts from 15 minutes to 3 hours, and attacks occur in series several times a day for weeks and months.

What Causes Cluster Headache

The exact cause is unknown. A sudden release of histamine and serotonin in the area of the trigeminal nerve on the face and the function of the hypothalamus — a small area at the base of the brain — are discussed.

The biological clock hypothesis explains the main point: attacks are tied to the time of day and to the season. Vasodilation in this case is considered a consequence, not a cause.

It affects men aged 30–40 more often; onset is possible at any age, but usually between 20 and 50 years. The male-to-female ratio is approximately 6:1, and a familial predisposition can be traced.

In 1972, physician John Graham described the typical appearance of the patient: a large, muscular man, up to 94% of whom smoked more than 30 cigarettes a day. There is still no explanation for these observations.

Among the triggers are alcohol, smoking, strong odors — perfume, paint, gasoline — as well as physical exertion, bright light, heat, and foods containing nitrites.

How the Diagnosis Is Made

There are no specific tests. The doctor asks about the character, localization, and frequency of the pain, about other symptoms, and about what preceded the attack.

Examination during an attack may reveal Horner's syndrome — drooping of the eyelid and constriction of the pupil on the side of the pain; outside an attack these signs are absent. To rule out other causes, an MRI of the brain is ordered.

A diary helps: the time of onset, sleep, food and drinks in the preceding 24 hours, and the duration of the attack.

When a Headache Requires Urgent Medical Attention

See a doctor if attacks recur, if ordinary painkillers such as ibuprofen and paracetamol do not help, if the pain makes it impossible to sit still. Another reason is worsening of a known condition: attacks have become more frequent or longer than usual.

Particular caution is warranted for jaw pain when chewing, blurred or double vision, tenderness of the scalp, numbness or weakness in the arms and legs: this may be how inflammation of the temporal arteries manifests.

Cluster headache by itself is not a reason to call an ambulance. Call 103 or 112 if an eyelid has drooped for the first time or one pupil has become smaller than the other, if the headache arose suddenly and turned out to be the most severe of your life, if speech, vision, movement, or balance are impaired, if the pain is accompanied by repeated vomiting, high fever, or neck stiffness.

Cluster headache does not threaten life and usually leaves no persistent changes in the brain, but it is chronic and interferes with work and life; with age, attacks may become less frequent. This material is for reference and does not replace consultation with a doctor.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer