Cluster headache: The most painful condition known to humankind?

What is a cluster headache exactly, and how does it differ from a normal headache? We asked Dr Mark Weatherall, consultant neurologist with a subspecialist interest in the management of headaches.

What a cluster headache is like

Cluster headache is one of the most painful medical conditions known to humankind. It is characterized by very severe, one-sided headaches, usually around or above the eye. These last 15-180 minutes and can occur up to eight times a day.

Attacks often come at the same time of the day or night, leading to the name ‘alarm clock headache’. Other symptoms can often include:

• redness of the eye
• tears
• nasal congestion
• forehead or facial sweating
• drooping or swelling of the eyelid

Living with cluster headache

Most sufferers have episodic cluster headache, in which attacks come in bouts, usually lasting a few weeks, and often in the spring or autumn. A small proportion have chronic cluster headache, in which attacks continue for months or years at a time with no remission.

Cluster headaches have a huge impact on sufferers’ work and social lives . One-quarter of patients experience absenteeism or job loss, and nearly one in ten are unemployed or on disability payments because of their disorder.

The excruciating intensity of the attacks has led some people to dub it the ‘suicide headache’.

Why cluster headaches happen

Cluster headache is slightly more common in men than women, and often starts in the 20s or 30s, though it can occur later in life.

In rare cases, cluster headache runs through families, indicating a genetic component, but no specific genetic abnormality has yet been discovered. Functional brain scans show that central brain mechanisms (particularly in the hypothalamus) play pivotal roles in the condition.

Unlike migraine, cluster headaches are rarely triggered by external factors, though some patients find that when they are in a bout, alcohol will set off an attack almost instantly.

The good news is that cluster headaches can be treated

The main focus of therapy is to abort attacks once they have begun and to prevent future attacks. Cluster headache attacks need fast-acting abortive agents because the pain peaks very quickly. The painkiller sumatriptan (given as a nasal spray or a subcutaneous injection) and high flow 100% oxygen are the only effective acute treatments.

First line preventative drugs include verapamil and lithium. A course of steroids can be effective in settling down a cluster bout, as can an occipital nerve block with local anaesthetic and steroid.

If these treatments don’t work we can offer various forms of neurostimulation, including:

• occipital nerve stimulation
• vagus nerve stimulation
• sphenopalatine ganglion stimulation
• hypothalamic stimulation

Finally, a number of trials are ongoing to explore new types of treatment for cluster headache. For example, monoclonal antibodies could be engineered to fight against calcitonin gene-related peptide (CGRP). This could in turn desensitise the neurons in the head and prevent the onset of cluster headache attacks.

In the future, we can look forward to significant improvements in how we manage cluster headache, and restore quality of life to the many people affected.