The Clinical Syndrome
Sudden unilateral neuralgiform conjunctival injection tearing (SUNCT) headache is an uncommon primary headache disorder that is one of a group of three headache syndromes known as the trigeminal autonomic cephalgias ( Table 8.1 ). Whether SUNCT headache is in fact a distinct headache entity or simply a constellation of symptoms that occurs on a continuum along with the other trigeminal autonomic cephalgias is a point of ongoing debate among headache and pain management specialists ( Fig. 8.1 ). As with most headache syndromes, the exact cause of the pain of SUNCT headache is unknown; however, the pathogenesis of this uncommon cause of head and face pain is thought to be dysfunction of the trigeminal autonomic reflex.
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The pain of SUNCT headache has a rapid onset to peak, with attacks lasting 5 seconds to 4 minutes and the frequency of attacks ranging from 20 to 200 attacks per day. In some patients, these attacks can be triggered by sensory stimulation of the affected areas, such as when washing the face, brushing the teeth, and so forth. Although in many ways similar to cluster headache (e.g., unilateral, periorbital, and frontal location of pain, sclera injection, rapid onset to peak, short duration of attacks, and pain-free periods between attacks), SUNCT exhibits many dissimilarities as well. In contrast to cluster headache, alcohol consumption does not seem to trigger attacks of SUNCT headache, and there do not seem to be the seasonal and chronobiological patterns so characteristic of cluster headache, although SUNCT headache occurs most frequently in the morning and afternoon ( Table 8.2 ).
| Comparison Factors | Cluster Headache | SUNCT Headache |
|---|---|---|
| Ocular and retroorbital location | Yes | Yes |
| Unilateral | Yes | Yes |
| Rapid onset to peak | Yes | Yes |
| Severe intensity | Yes | Yes |
| Attacks occur in paroxysms | Yes | Yes |
| Duration of attacks short | Yes | Yes |
| Pain free between attacks | Yes | Yes |
| Significant rhinorrhea during attacks | Yes | No |
| Alcohol triggers attacks | Yes | No |
| Tactile trigger areas | No | Yes |
| Seasonal pattern of attacks | Yes | No |
| Chronobiological pattern of attacks | Yes | No |
| Significant eye inflammation | No | Yes |
| Responds to sphenopalatine ganglion block | Yes | No |
| Responds to trigeminal nerve block | No | Yes |
Blockade of the sphenopalatine ganglion, which is so effective in the treatment of cluster headache, is of little value in the treatment of SUNCT headache. Patients suffering from SUNCT headache may respond to daily trigeminal nerve blocks with local anesthetic, as described subsequently.
Signs and Symptoms
Patients with SUNCT headache present with the complaint of severe paroxysms of ocular or periorbital pain that radiate into the ipsilateral temple, forehead, nose, cheek, throat, and maxillary region. This pain is associated with significant inflammation of the affected eye and associated autonomic signs and symptoms ( Figs 8.2 and 8.3 ). The pain is neuralgiform and severe to excruciating in intensity ( Table 8.3 ). SUNCT occurs on the right side 70% of the time in a manner analogous to trigeminal neuralgia. Like trigeminal neuralgia, rare cases of bilateral SUNCT headache have been reported. Also, like trigeminal neuralgia, the pain of SUNCT headache rarely switches sides. SUNCT headache occurs slightly more frequently in males. It can occur at any age, with a peak incidence in the fifth decade.
