Abstract
Both SUNCT syndrome and idiopathic stabbing headache (ISH) (jabs and jolts syndrome) have to be considered when encountering shortlasting headaches. Since there are no specific tests for these headaches, the differential diagnosis depends entirely upon assessment of the clinical features. These headaches are generally easily distinguishable clinically. There seem to be symptomatic forms of SUNCT.
Keywords
With attacks in the range of less than 1 sec to 1–2 min, and with a unilateral, orbital localization, one may be faced with three primary headache categories: idiopathic stabbing headache (ISH) (1) (jabs and jolts syndrome), first branch trigeminal neuralgia (V-1 tic), or SUNCT syndrome (2). In the exceptional case, one may also have to deal with the most shortlasting (3 m) CPH attacks (3). Moreover, stabbing pain and V-1 tic may rarely be concurrent with CPH attacks (4 –6). All those headaches have to be considered when encountering short-lived, periorbital pain syndromes.
Two proposals on the diagnostic criteria of SUNCT have recently been published (7, 8), whereas the International Headache Society (IHS) criteria for ISH, have been available since 1988 (9). In this communication, we have endeavored to compare ISH with SUNCT clinically in order to emphasize the differences.
Sex ratio and age at onset
There is a remarkable difference in sex predominance between these headaches (7). ISH (10) is a headache mostly associated with females (male/ female sex ratio of 0.15, n = 38), whereas SUNCT prevails in males (male/female ratio of 4.25, n = 21) (p < 0.001, Chi-squared test) (11).
Although age at onset may be similar in both headaches (44–50 years), there is a remarkable qualitative difference: contrary to SUNCT, ISH may start in childhood (10, 12).
Localization and dynamics of pain
Usually, unilateral headaches have their origin in a lateral lesion or dysfunction. In ISH pain attacks are multidirectional from the onset of the headache. Although a solitary series may be side-locked—frequently in the orbit (1, 9, 10)—generally the attacks tend to change from one area to the next in either the same or the opposite hemicranium. Anterior areas are more frequently involved than occipital areas (10, 13), whereas the face is spared as a rule. Synchronous stabs in both halves of the head may also occur, and these can be either symmetric or asymmmetric. This lack of topographic organization with multifocal and rather chaotic localizations may reflect a mulriorigin of paroxysms—probably elicited in single fibers of the pericranial nerves (14), mostly of the V-1 branch (9). This is clearly contrary to SUNCT, in which attacks are confined to one periocular area (2, 11). In SUNCT, the paroxysmal pain neither substantially crosses the midline nor has an extratrigeminal (e.g. occipital) involvement been reported (11).
It is worth noting that a substantial number of patients suffering from ISH may have orbital attacks exclusively (1, 9, 10). In such cases, the differentiation from SUNCT has to be made on other characteristics, e.g., duration, accompaniments, precipitating mechanisms, etc.
Duration and frequency of attacks
Typical attacks in SUNCT (15) are 60 times longer than typical ISH attacks—duration of 1 sec or less (9, 10). This difference in duration of attacks between ISH and SUNCT is even wider than the one found between other orbital headache syndromes, such as cluster headache (mean 30 min (16)) and CPH (median 13 min (3)). So, in most cases, there should be few problems in differentiating these headaches on the basis of duration of attacks. However, ISH may last more than 1 sec (up to 10 sec) (10, 17) and SUNCT paroxysms may last down to 5–10 sec (15). Although there may be some overlapping at the extremes of the ranges of duration, patients presenting with attacks of for example SUNCT in the lower limit of the range of duration are very unusual (15), and even in patients exhibiting such short attacks the vast majority last longer than 10 sec.
The frequency of attacks varies immensely in both headaches. In SUNCT, attack frequency ranges from less than one attack per day to 30 per hour (2, 11). The frequency of ISH is from one stab yearly to 50 daily (10). A status-like pattern has been described in both disorders (13, 18), which tend to exhibit symptomatic periods alternating with remissions in an erratic fashion. We have also seen patients with ISH exhibiting a long-term chronic pattern. In SUNCT, a chronic pattern has not been observed so far.
Precipitating mechanisms
Attacks in ISH seem to be spontaneous. Some patients, nevertheless, have the impression that some attacks can be precipitated by emotional stress, bright light, postural changes, or head movements (10, 19). In SUNCT, there may also be spontaneous attacks, but paroxysms are usually triggered by stimuli acting mostly on trigeminal innervated areas. Paroxysms can also be triggered from extratrigeminal territory (2, 11). This may point to substantial differences between these two headaches as regards type of fibers or as regards the actual state of the activated receptors or nerve fibers. Precipitating mechanisms seem to be legion in SUNCT (2, 11).
Accompaniments
As a rule, pain is the only manifestation of ISH. In SUNCT, lacrimation and conjunctival injection virtually always appear together, and both with dramatic intensity (2, 11). In addition, rhinorrhea or nasal congestion are frequent accompaniments of SUNCT attacks (2, 11).
In SUNCT, a condition in which an “explosive”, and visible, dilatation of vessels in both the eye and eyelids takes place, it has been demonstrated that during attacks there is a marked increase in intraocular pressure and corneal indentation pulse amplitudes, probably related to vasodilatation and increased blood flow into the orbit (20). This feature suggests, as do many others, that in SUNCT, in addition to the neuralgiform pain, there is a vascular component with a clinical expression. In ISH, there are no available data on ictal dynamic tonometry as yet. In this headache, the brevity of attacks makes such an investigation almost utopic.
Conjunctival hemorrhage episodes in the symptomatic side is a striking phenomenon that we have observed in the exceptional case of ISH and SUNCT—as well as in V-1 tic, CPH, and cluster headache. Conjunctival bleeding is obviously produced by rupture of the wall of a conjunctival vessel. Whether an underlying vascular fragility diathesis is common to all the orbital headache syndromes is uncertain.
Treatment
There is no available treatment for SUNCT as yet (21). Many drugs and anesthetic blockades of pericranial nerves have failed substantially to alleviate patients suffering from SUNCT. Conversely, indomethacin may provide a partial improvement for patients suffering from ISH (10, 22).
Comments
Symptomatic forms of SUNCT syndrome are encountered frequently, and in such cases either a vascular malformation in the cerebelopontine angle (23, 24) or a pontine cavernous angioma (25) on the symptomatic side have been reported. ISH does not seem to have secondary forms.
ISH frequently coexist with other primary headaches, such as migraine (1, 19, 26), tension-type headache (26), cervicogenic headache (27), hemi-crania continua (28, 29), cluster headache (30, 31), and CPH (6, 32). Coexisting headaches may be concurrent or both types of pain can occur independently. Stabbing paroxysms may also herald the onset of CPH attacks (6, 32) or these can occur at the end of cluster headache attacks (31). Possibly, ISH may also coexist with SUNCT (33) and Giant cells arteritis (19).
Although there are no specific tests for SUNCT and ISH, both headaches are generally readily distinguishable, clinically. The differential diagnosis versus V-1 tic must be clarified in the individual SUNCT (34) or ISH patients.