Abstract
Shortlasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) syndrome is characterized by shortlived (5–240 s), strictly unilateral, periorbital, severe pain attacks, accompanied by ipsilateral conjunctival injection and lacrimation (1).
SUNCT syndrome has been classified together with cluster headache (CH) and paroxysmal hemicrania (PH) in the group of trigeminal autonomic cephalalgias (TAC) (1). The temporal pattern usually described in episodic SUNCT is irregular, with the symptomatic periods alternating with remissions in an erratic fashion (2, 3). In contrast, it is widely acknowledged that in episodic CH bouts can occur in the same periods every year (4), particularly during spring and autumn (5), and in some PH patients seasonal variations have been described (6–8). We present a patient with episodic SUNCT syndrome with bouts that occurred twice annually in spring and autumn.
Case report
A 60-year-old, right-handed male was referred to our Headache Unit with a 9-year history of headache attacks that occurred in seasonal series, with cycles in autumn (September) and spring (February–March). The cycles lasted between 2 and 8 weeks and were separated by pain-free periods. The frequency of attacks during the symptomatic phase ranged between 1 and 10 per hour. The headache was located in the left periorbital and maxillary region, lasted 8–12 s and was associated with ipsilateral lacrimation, conjunctival injection, and occasionally rhinorrhoea. The pain was described as sharp and the patient rated his most painful attacks at 10/10 on the verbal rating scale (VRS). The type of attack he described was the saw-tooth pattern (2, 3). He was completely pain free between attacks. The patient could precipitate his attacks by touching his face, talking, shaving, eating, chewing, or brushing teeth. He could experience one attack spontaneously occurring immediately after the previous one, or could trigger an attack immediately on top of the previous one. The episodes were not triggered by alcohol. The patient had previously been misdiagnosed as having trigeminal neuralgia and treated with pregabalin (150 mg/day), and gabapentin (900 mg/day) without benefit. His past medical history was remarkable for hypercholesterolaemia (treated with statins) and hyperuricaemia. He had smoked 5 cigars per day for the last 30 years. General and neurological examinations were normal between attacks. There was no tenderness in the the suboccipital region. Brain magnetic resonance imaging without contrast, including views of the trigeminal nerve, was normal. A diagnosis of SUNCT syndrome was made. We performed a greater occipital nerve (GON) blockade with steroids and local anaesthetic, as previously reported by Afridi SK et al. (9). The patient was followed up with telephone calls, and 2 days after the injection there was a reduction in severity and frequency of headache. However, after 1 week the patient continued to have one to three mild attacks (2–4 out of 10 on the VRS) per day, so lamotrigine was prescribed, which resulted in complete suppression of the pain at a dose of 300 mg/day. After 6 months, the patient tried to stop lamotrigine, causing reappearance of the attacks when the dose was reduced to <150mg/day. The attacks did not appear spontaneously thereafter, only being triggered by touching his face and particularly while eating, and there was a refractory period between attacks, so he could not trigger an attack immediately after the previous one. Lamotrigine was increased to 300 mg/day, which led to an improvement, and 1 year later the patient is asymptomatic.
Discussion
Our patient suffered multiple severe left periorbital pain lasting 8–12 s with ipsilateral autonomic features which fulfilled the International Headache Society diagnostic criteria for SUNCT syndrome (1). The attacks occurred in seasonal periods, with cycles in autumn and spring, as has been previously described in CH and PH patients (5–8). To the best of our knowledge, this is the first case of episodic SUNCT syndrome with seasonal periodicity.
SUNCT syndrome has been traditionally described in an episodic form, with symptomatic periods alternating with remissions in an erratic manner (2). Recently, in a large and extensively studied series of episodic SUNCT patients, Cohen et al. (3) found that the primary episodic form of the disease accounts for only 13% of patients. The bouts of episodic SUNCT last from a few days to several months and occur once to twice annually, but without a seasonal pattern. Seasonal fluctuations of pain attacks observed in our patient once again underline the importance of the hypothalamic region in the pathophysiology of SUNCT. Functional imaging studies have demonstrated posterior hypothalamic activation in CH (10), PH (11), SUNCT syndrome (12) or TAC not otherwise differentiated (13). The importance of the hypothalamus in SUNCT syndrome has been underlined by the report of one patient successfully treated with hypothalamic deep brain stimulation (14). All these findings suggest that TACs share common pathophysiological mechanisms and that there may well be overlap in the clinical features within the TAC group, as the circannual periodicity observed in our SUNCT patient suggests.
We treated our patient with a single injection in the region of the GON, which resulted in partial improvement within 72 h. GON blockade has been succesfully used for short-term preventative treatment in episodic CH (9) and PH (6), but was considered ineffective for SUNCT (15). The clinical phenotype of our patient, with the unmistakable circannual periodicity, might suggest a similar therapeutic response to transitional prophylaxis with GON injection, as observed in other TACs.
On the other hand, on his first visit our patient was able to trigger his attacks one after the other, which demonstrated that there were no refractory periods. When he reduced the dose of lamotrigine the pain reappeared, but interestingly he clearly had a refractory period between attacks. The presence of a refractory period can probably be explained by an inhibitory effect of lamotrigine on trigeminovascular nociceptive neurons. Although the absence of a refractory period may be useful to distinguish between trigeminal neuralgia and SUNCT (2, 3), this clinical feature can be modified by treatment with antiepileptic drugs such as lamotrigine. Discontinuation of lamotrigine was not possible because of recurrence of the attacks. Our patient has probably evolved from an episodic to a chronic SUNCT after 9 years, as described by Cohen et al. (3).