Abstract
Introduction
Trigeminal neuralgia (TN) is the most important syndrome among the pain disorders over the V nerve area. Although the underlying mechanism remains partially unknown, the effect of direct stimulation by a closely related blood vessel is the most common related abnormality in TN (1). Experimental stimulation of the V nerve may produce ocular autonomic disorders as well as neuropeptide release (2, 3), supporting the mechanical hypothesis. In the rather narrow group of disorders recently coined as ‘trigeminal-autonomic cephalalgias’ (TACs) (4), including SUNCT syndrome, chronic paroxysmal hemicrania (CPH) and cluster headache, a primary aetiology is hardly identified. Central abnormalities in cluster headache (5) do not explain the role of peripheral lesions in this disorder (6–8). Interestingly enough, TN and a TAC may occur simultaneously or independently, but always at the same side of the head (9, 10). We describe the case of a patient presenting initially with a trigeminal-autonomic cephalalgia, later evolving into a typical first branch trigeminal neuralgia, in which the most intriguing feature is the presence of dual pathology at different spots along the trigeminal pathway.
Case report
A 40-year-old white male, started at the age of 25 to suffer from daily episodes of right orbital and periorbital short-lasting headaches initiating at the supraorbital area and irradiating to the ipsilateral V1 and V2 territories. The pain was boring and not pulsatile in nature, intense from the beginning, lasting 40–50 s, decreasing abruptly and leaving no residual symptoms or signs except for some eventual itching in the fronto-parietal scalp. There was oedema and erythema of the eyelids, associated with conjunctival injection and mild tearing. The autonomic features were bilateral but most marked in his right eye (Fig. 1). Pain was almost always triggered by bending the head forwards while standing or by turning the head while asleep, and eventually by touching his right periorbital area, glancing rightwards, washing his face or brushing his teeth. Due to the severity of the pain the patient would pace the floor crying, yelling, sometimes banging his head against the wall. Episodes of pain would occur even four times an hour, sometimes with a 5-min interval. The pain was not responsive to any common analgesic. His past medical history was unremarkable except for appendectomy at the age of 10 and an injury to his right fifth finger at the age of 26. The physical examination showed a right nasal cavity obstruction and the aforementioned autonomic features during attacks. Indomethacin 25 mg t.i.d. apparently reduced the attacks to only three episodes a day, lasting 30 min each, and led to some epigastric distress. A CT scan of the head showed a lesion in his right maxillary sinus, thinning and bulging the sinus wall laterally towards the zygomatic fossa and medially towards the nasal septum (Fig. 2). A dense fluid was removed during operation and the diagnosis of mucocele (mucus retention cyst) was considered. The paroxysmal pain remitted and the continuous post-operative low-grade local pain ensued, slowly remitting within a month. Six months after the operation a pain ensued, but then as a first branch trigeminal neuralgia pattern, without autonomic accompaniments. A neuralgic pain lasting a few seconds would occur less often during the day, spontaneously or triggered by tactile stimuli on the right trigeminal first branch territory. Head tilting no longer triggered pain, and remitted shortly after oxcarbazepine 300 mg b.i.d. was started. A brain MR imaging showed a venous angioma, extending from the right cerebellar peduncle up to the right trigeminal ganglium (Figs 3 and 4). Oxcarbazepine was maintained for 4 months, without immediate pain recurrence after it was withdrawn. Since then, neuralgic pain has recurred yearly, always being easily controlled by oxcarbazepine therapy.
Patient during a paroxysm of pain. Note bilateral lower palpebral oedema, most marked at the right side (arrow).
Computerized tomography scan image of the head showing soft tissue density fulfilling the right maxillary sinus (∗).
Transversal MR images of the head revealing a venous angioma extending from the right cerebellar peduncle to the right Gasserian ganglion (circle).
Coronal MR images of the head revealing a venous angioma extending from the right cerebellar peduncle to the right Gasserian ganglion (circle).
Discussion
Differential diagnosis between TN and the TACs has been reviewed in previous literature (11–13). Important similarities shared by first branch TN and SUNCT syndrome include the distribution of pain and the autonomic phenomena, less frequent but undoubtedly present in some patients with the former disorder (12, 13). It has been reported that, in first branch TN, autonomic phenomena, especially lacrimation, could depend on the severity or the duration of the attacks (12, 13), possibly leading to supraliminar parasympathetic activation. Nevertheless, the two groups of headache disorders, TACs and TN, differ regarding pain triggering and attack duration, circadian and circannual patterns, and autonomic phenomena (4, 11–13), making a common pathophysiology unlikely.
The present case presented first with a trigeminal-autonomic syndrome, with remission after the drainage of the mucocele, suggesting a local hypertensive effect over parasympathetic and/or other autonomic fibres. A partial response to indomethacin could raise the possibility of CPH traits, but higher doses of this drug were not tried. However, episodes of pain would occur during sleep only triggered by head turning, apparently not locked to any sleep phase such as CPH. A reason to ascribe the pain to the mucocele was the characteristic triggering by head tilting as in sinus disorders (14), but not to cervical digital pressure, as would be expected in some CPH cases (15). Moreover, stimulation of maxillary and carotid vessels in humans has been shown to cause facial pain (16, 17). The associated autonomic symptoms could perhaps be explained by co-involvement of ectopic or aberrant parasympathetic neurones (18). The recurrence of pain as a first branch TN may occur because of the contact between vascular structures and the trigeminal nerve that has been reported in up to 90% of such cases (19).
At least two cases of trigeminal neuralgia evolving to SUNCT syndrome have been described (20, 21). The existence of a symptomatic trigeminal-autonomic cephalalgia evolving to a trigeminal neuralgia, secondary to dual pathology at different sites of the trigeminal pathways, suggests that the clinical picture of disorders affecting trigeminal pathways will vary according to the level of the lesion as well as its degree and nature.