Abstract
Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) syndrome is a rare headache syndrome classified among the trigeminal autonomic cephalalgias. It is usually idiopathic, although infrequent secondary forms have been described. Recently the term short-lasting unilateral headache with cranial autonomic symptoms (SUNA) has been defined by the International Headache Society (ICHD-2) as similar to SUNCT with less prominent or absent conjunctival injection and lacrimation. We report two patients with paroxysmal orbito-fronto-temporal pains, phenotypically suggesting SUNA, occurring after traumatic head injury.
Patient 1
This 29-year-old man had a road traffic accident in 2002, which resulted in upper gum laceration, loss of several teeth and mandibular fracture without skull fracture or intracranial lesions. The right mandibular fracture was repaired by osteosynthesis using metal plates and screws, approximately a week after the injury. Within 4 weeks, he started experiencing severe episodic sharp stabbing headaches in the right frontal and orbital regions (ipsilateral to the injury) radiating to the temporal area, lasting between 10 and 60 s, with a sense of forehead sweating on the same side. The forehead sweating was frequently witnessed by his partner, during the attacks. The episodes occurred five to 10 times daily, without any refractory period. No reddening or tearing of the right eye was described, nor did the patient report any ptosis, miosis, nasal congestion or rhinorrhoea. He could not describe any obvious triggers to these pains. His past medical history was unremarkable, with no previous headaches being reported. There was no relevant family history. He was referred to our Neurology Unit in 2004. On examination, he had a large right frontal scar that had resulted from a superficial cut caused by the accident. Right facial dysaesthesia to pinprick was detected in the first division of the trigeminal nerve (V1) on sensory examination. He denied having any spontaneous facial hyperalgesia. There was no evidence of Horner's syndrome or other focal neurological features. Fundoscopy was normal. Magnetic resonance imaging (MRI) of the brain with fine cuts through the trigeminal nerve revealed a vascular loop in close proximity to the right trigeminal nerve.
The patient was put on a trial of treatment with gabapentin at the dose of 300 mg three times daily. He experienced a rapid and dramatic response, describing on follow-up only one episode of pain on average weekly, since being on treatment. Gabapentin was gradually withdrawn with no further relapses reported at last review.
Patient 2
This previously fit 24-year-old woman had suffered a road traffic accident, her car having been hit from behind at about 97 km/h on a motorway. She developed whiplash-like symptoms, but with no obvious external head injury. There were no focal neurological signs and the cervical spine was therefore not imaged. The next day she started experiencing sharp stabbing pains in the right infra-orbital region radiating to the forehead. These pains lasted for 2–3 min and could happen two to eight times a day. The patient had objective periorbital swelling, ipsilateral ptosis and tearing during these episodes that were apparent to her boyfriend. The pains could be triggered by bright sunlight, putting on contact lenses or watching television, with no noticeable refractory period. There was no history of nocturnal attacks, but the patient reported waking up at night, feeling that her eye was swollen and puffy. There was no previous personal or family history of headaches. On examination, there was tenderness and reduced pin-prick sensation in the right infra-orbital region. There were no other focal neurological abnormalities with normal pupillary responses. MRI of the brain was normal. After initiation of carbamazepine (Tegretol Retard®) 200 mg bd (4 months after the occurrence of pain), the frequency of attacks reduced to a maximum of one to two per day, with pain-free intervals of up to 4 days. Two months later, as the patient was considering becoming pregnant, she gradually withdrew the carbamazepine. This led to a resurgence of attacks, occurring three to five times a day, with occasional longer attacks lasting up to 10 min.
Discussion
Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) represents a rare headache syndrome, belonging to a group of headache syndromes classified as trigeminal autonomic cephalalgias (TACs). It causes episodic pains lasting between 5 and 250 s, with occasional longer bouts. Up to 30 episodes may occur per hour, although frequency may vary. Triggers are common and can consist of cutaneous stimuli or neck movements. The pain is unilateral and accompanied by ipsilateral conjunctival injection and tearing, which are often the most prominent autonomic features. However, some of these features may occasionally be absent. SUNCT is idiopathic, although few secondary cases are described, mostly with underlying vascular and posterior fossa lesions (1). To our knowledge, one case of possible SUNCT has been reported after traumatic head injury (2) and four cases had head or facial trauma as the precipitating event in a large series (3). Headaches following head injury occur usually within 4 weeks of trauma [International Headache Society (IHS) 5, International Classification of Diseases (ICD) G44.88] and are mostly of the tension-type, although migraine and cluster-like episodes are occasionally seen (4).
In view of the forehead sweating and the absence of conjunctival congestion or tearing in the first patient and the absence of conjunctival congestion in the second patient, both patients satisfy the definition of SUNA (IHS 3.4.3, ICD G44.08) (4). Similar to the previously described case of post-traumatic SUNCT (2), our patients developed trigeminal facial pains after an interval (24 h to 4 weeks) following the head injury, and have had sensory involvement of V1 indicating probable post-traumatic dysfunction of the first division of the right trigeminal nerve and modulation of the sensory afferent pathway. Minor sensory deficits in V1 have been described in 12% of SUNCT patients in a recent series (3). Our second patient did not have any cervical imaging at the time of injury, since it was felt that she did not have any physical signs to warrant it. It is conceivable that detailed imaging of the cervical spine would have shown some evidence of high cervical cord injury, thus implying a role of the trigeminocervical complex in the pathophysiology of this syndrome.
Since trigeminal neuralgia (TN) affecting the V1 distribution is more likely to be associated with some autonomic symptoms (5), it could be argued that our patients with the distribution of pain and forehead sweating had a post-traumatic TN. However, the average duration of pain was much more prolonged than in TN with no refractory period between attacks, which is characteristic of typical TN (1). Pains in TN are paroxysmal, but only exceptionally affect the first trigeminal branch (V1) in isolation (5), as is the case in SUNCT. Each attack lasts for < 5 s (range 2–32 s) (6) and are most common in the second and third trigeminal divisions (V2, V3), pure ophthalmic branch involvement, as in SUNCT, being rare (1, 5, 6).
The distinction between TN and SUNCT remains difficult in some cases, and it is possible that these two disorders represent different forms of the same entity and share a common pathophysiology (7–9). Co-existence of TN and SUNCT in the same patient further favours this hypothesis (8, 10, 11). Bilateral hypothalamic activation has been described with headaches phenotypically resembling SUNCT and responding dramatically to ipsilateral trigeminal nerve decompression (12). Trigeminovascular compression could have triggered the trigemino-autonomic reflex, at least in patient 1, as suggested previously (13). The presence of a vascular loop near the trigeminal nerve has been reported both in TN and TACs (14, 15), as in our first patient. Animal studies have also provided evidence for the role of the trigemino-hypothalamic tract in conveying the nociceptive sensory signals directly to the hypothalamus (16).
Although SUNCT is considered the most common subset of SUNA (3, 17), recent studies have shown that patients with SUNA (i.e. with minimal conjunctival injection and tearing) seem to have bilateral negative hypothalamic activation on functional imaging (17). Patients with symptomatic SUNCT showed no hypothalamic activation in this study (17). The close temporal relationship of the event, which also happened ipsilateral to the site of pain (in our first patient), would suggest a causal relationship between the injury and the headache syndrome (18).
Our patients responded to the first agents tried, gabapentin and carbamazepine, respectively, which are reported to be effective both in TN and SUNCT. In the absence of strict definitions of these two conditions, precise classification of our cases is difficult and, as for Putzki et al.'s patient (2), one could justifiably use the terms ‘post-traumatic SUNA’ or ‘post-traumatic TN’ for such cases of paroxysmal V1 territory pains following cranio-facial injury. The features in these two patients are more in keeping with post-traumatic SUNA. These cases highlight the substantial clinical overlap between the two headache syndromes, strengthening the theory of a shared pathophysiology. Further structural and functional imaging of several cases of primary and post-traumatic trigeminal cephalalgias could give more insight into the pathophysiological basis of these two conditions.