The acronym SUNCT (short-lasting unilateral neuralgiform attacks with conjunctival injection and tearing), another primary headache, has been applied to an episodic condition with attacks of even briefer duration, but otherwise similar to paroxysmal hemicrania in which the supraorbital or temporal pain lasts up to 4 min or so and is frequent; it does not usually respond to indomethacin.
A similar hemicrania but without autonomic features, may be symptomatic of lesions near the cavernous sinus (mainly pituitary adenoma) or in the posterior fossa, but most cases are idiopathic. The typical episode of pain lasts approximately 20 min. Also known is a recurrent nocturnal headache in elderly individuals (“hypnic headache”), as described further on.
The relationship of cluster headache and all of its variants to migraine remains conjectural. No doubt the headaches in some persons have some of the characteristics of both, hence the terms migrainous neuralgia and cluster migraine (Kudrow). Lance and others, however, have pointed out differences that seem important to us: flushing of the face on the side of a cluster headache and pallor in migraine; increased intraocular pressure in cluster headache, normal pressure in migraine; increased skin temperature over the forehead, temple, and cheek in cluster headache, decreased temperature in migraine; and notable distinctions in sex distribution, age of onset, rhythmicity, and other clinical features, but prominently by differences among them in response to specific treatments. Cluster may be triggered in sensitive patients by the use of nitroglycerin and, as mentioned, by alcohol.
The cause and mechanism of the cluster headache syndrome are unknown. Gardner and coworkers originally postulated a paroxysmal parasympathetic discharge mediated through the greater superficial petrosal nerve and sphenopalatine ganglion. These authors obtained inconsistent results by cutting the nerve, but others (Kittrelle et al) reported that application of cocaine or lidocaine to the region of the sphenopalatine fossa (via the nostril) consistently aborts attacks of cluster headache. Capsaicin, applied over the affected region of the forehead and scalp, may have the same effect. Stimulation of the ganglion is said to reproduce the syndrome. Kunkle, on the basis of a large personal experience, concluded that the pain arises from the internal carotid artery, in the canal through which it ascends in the petrous portion of the temporal bone. In the course of an arteriogram, during which a patient with cluster headaches fortuitously developed an attack, Ekbom and Greitz noted a narrowing of the artery that was interpreted as being caused by swelling of the arterial wall, which, in turn, compromised the pericarotid sympathetic plexus and caused the Horner syndrome. This remains to be confirmed.
The cyclic nature of the attacks has been linked to a hypothalamic mechanism that governs the circadian rhythm. At the onset of the headache, the region of the suprachiasmatic nucleus appears to be active on PET (May et al). Hypothalamic activation has also been found in migraine, SUNCT, chronic paroxysmal hemicrania, and hemicrania continua. Moreover, stimulation of the hypothalamus has proved effective, although highly experimental, in stopping chronic cluster headache and SUNCT (see Leone et al and Bartsch et al).
Much was made in the past of the fact that cluster headaches could be reproduced by the intravenous injection of 0.1 mg histamine, but the effect was probably nonspecific. Goadsby has reviewed the pathophysiology of the cluster headache syndrome.
Treatment of Cluster Headache