This is the second post of a three-part series dealing with the most frequently asked questions about migraine and headache, based on the Karger publication “Migräne & Kopfschmerzen. Ein Fachbuch für Hausärzte, Fachärzte, Therapeuten und Betroffene” (“Migraine & Headache. A Reference Book for General Practitioners, Specialists, Therapists and Persons Concerned”).

This article gives answers to six frequently asked questions about cluster headaches.

What are cluster headaches?

Cluster headaches are primary headaches because their causes are still unclear. These headaches are exceptionally severe and always occur on the same side of the head. They are accompanied by so-called autonomic signs such as reddened eye, runny nose and others. The attacks are much shorter than in migraine and tension headaches, but often occur several times a day. The word cluster indicates a typical cluster of attacks in the spring. After these episodes, cluster attacks often disappear for months to years.

What are the causes of cluster headaches?

Dilatation or inflammation of blood vessels is not the cause of cluster headache, as previously thought, but rather its consequence. Features of inflammation in the cavernous sinus have not been demonstrated in studies.

Certain pain-conducting pathways in the area of the trigeminal nerve are probably stimulated by as yet unknown influences, leading to a cascade of changes in brain metabolism. The origin of the disorder is thought to be in the hypothalamus or thalamus, two “switching centers” of the diencephalon and, in the case of the hypothalamus, center for the control of major regulatory circuits, such as the sleep-wake rhythm. The diurnal distribution patterns of cluster headaches, the striking frequency of episodes in spring and autumn, and the frequent disturbances in cluster headache patients of hormones that control the diurnal rhythm, such as melatonin, are indicative of such a disturbance.

What factors can trigger a cluster headache attack?

Cluster headache attacks are usually sparked by triggers. These are not the actual cause, but possible triggers of pain attacks. Known triggers are alcohol, histamines, nitroglycerin, flickering or bright light, food additives such as glutamate, potassium nitrite, sodium nitrite, odors (solvents, gasoline, adhesives, perfume), cheese, noise, chocolate, citrus fruits. Other possible triggers: heat, sleep disturbances, sleep apnea syndrome, prolonged exposure to chemicals, extreme anger or emotions, prolonged physical exertion, large changes in altitude. The effect of the various trigger factors varies greatly among patients.

How often do attacks of cluster headache usually occur?

An important feature of cluster headache is that the attacks occur several times a day. Typically, those affected by them report two to four attacks per day, but they may report up to ten or more.

What accompanying symptoms are associated with cluster headache?

Redness of one eye, tearing of the eyes, runny nose, drooping and swollen eyelid, constricted pupil, sweating on the head and others. Apart from sweating, these signs of autonomic nervous system disorder are always on the same side as the headache.

How are cluster headaches treated?

As with most headaches, a distinction must be made between attack and basic treatment. In cluster attacks, the time to onset of action is what counts because of the excruciating pain. Sumatriptan as a subcutaneous injection or pure oxygen via a face mask are the fastest and most effective. The nasal spray zolmitriptan has also proven effective. Before the introduction of sumatriptan, ergotamines were administered intravenously, but these very often led to vomiting and other unpleasant side effects. Intranasal lidocaine 4% can also act very quickly. All tablets are secondary because of the longer absorption time, but can also do a good job.

In basic treatment, i.e., prevention of further attacks, verapamil has gained worldwide acceptance, although very high doses are often necessary under medical supervision. Furthermore, prednisone (mostly initially concomitant until verapamil is increased), topiramate, lithium, melatonin, methysergide, ergotamine, valproate, gabapentin, Botox, electrical stimulators and others. All prophylactics are so-called off-label applications.

Information based on “Migräne & Kopfschmerzen. Ein Fachbuch für Hausärzte, Fachärzte, Therapeuten und Betroffene” (Karger, 2015).