Abstract
The trigeminal autonomic cephalgias (TACs) are a group of primary headache disorders characterized by a unilateral trigeminal distributed pain that occurs in association with prominent ipsilateral autonomic features. The group comprises cluster headache, paroxysmal hemicrania and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT syndrome). The treatment of paroxysmal hemicrania is prophylactic. Complete resolution of the headache with an appropriate dose of indomethacin is prompt, usually occurring within 1–2 days of initiating the effective dose. The mechanism behind the absolute responsiveness to indomethacin is unknown. It appears to be independent of indomethacin's effect on prostaglandin synthesis, since other non-steroidal anti-inflammatory drugs have little or no effect on paroxysmal hemicrania. For patients who do not respond or cannot tolerate indomethacin, one faces a difficult challenge, since no other treatment is consistently effective (1, 2).
Recently, Yangüela et al. have described primary trochlear headache (3). They suggest that the inner angle of the orbit is the origin of this type of headache, which is clearly dependent on both the sensitive input and dynamics of the trochlear apparatus, in the absence of local or systemic disease. Primary trochlear headache is an intraorbital, extraocular painful disorder, with maximum pain located in the inner–upper part of the orbit. Extension of pain to the ipsilateral forehead is observed in about two-thirds of cases. Several mechanical ancillary features, such as examination of the involved trochlear or vertical eye movements, exacerbate pain, which is relieved by injecting lidocaine or corticosteroids on the sore trochlea, but not by placebo. Primary trochlear headache can be associated with other types of headache such as tension-type headache or migraine (3).
We present a patient with an association of chronic paroxysmal hemicrania and primary trochlear headache in which local steroid infiltration indicated for the treatment of the latter headache resulted in relief of the symptoms of the former.
Case report
A 60-year-old woman came to the neurology out-patient clinic 5 years ago because of a long history of headache during the last 10 years. The patient had previously received treatment with β-blockers, flunarizine, amitriptyline, carbamazepine and prednisone without response. The pain was very severe and localized in the right supraorbital region. The duration of attacks was approximately 30 min and the frequency could reach 15 attacks per day. The pain was associated with ipsilateral ptosis and conjunctival injection. She did not present with diplopia and neurological examination was normal. No tenderness was observed in the trochlear area. A routine blood profile, including erythrocyte sedimentation rate (ESR), showed no abnormalities. A 1.5-T magnetic resonance imaging (MRI) study [spin-echo, T1, T2, fluid attenuated inversion recovery (FLAIR) and gadolinium-enhanced sequences] of the brain was also normal. With a diagnosis of chronic paroxysmal hemicrania, indomethacin was started at an initial dose of 75 mg/day in three separate doses and progressively increased up to 150 mg/day. The pain dramatically improved until disappearance. The patient remained free of symptoms for 4 years with a minimum maintenance dose of 25–75 mg/day.
One year ago she attended again and complained of a continuous intense pain localized to the right orbit with the same characteristics as previously, except for milder or almost absent autonomic features and subjective intermittent diplopia when she looked downwards. Neurological examination was normal without oculomotor palsies. Exploration of the trochlear area showed a sharp increase of pain when the patient moved the eye in supraduction. Blood tests, ESR, thyroid function, antinuclear antibodies, rheumatoid factor and routine urine analyses were normal. A new brain and orbital MRI failed to show abnormalities. At this time the patient was receiving a daily dose of 50 mg of indomethacin. The dose was increased to 150 mg, without evident response. For this reason and the presence of tenderness in the trochlear area, 1 ml of triamcinolone plus lidocaine was injected in the right trochlear area with complete pain relief. Indomethacin was suppressed and the patient remained free of symptoms until 4 months later. At this time, in conjunction with prolonged reading, pain reappeared with the same characteristics and localization. The same drugs were reinjected again in the trochlear region with complete relief of symptoms.
Discussion
Any pathophysiological hypothesis regarding the trigeminal autonomic cephalalgias must take into account the two major clinical features of the various conditions that comprise this group: trigeminal distribution of the pain and ipsilateral autonomic features (1, 4). The pain-producing innervation of the cranium projects through branches of the trigeminal and upper cervical nerves to the trigeminocervical complex, from where nociceptive pathways project to higher centres. This implies an integrational role for the ipsilateral trigeminal nociceptive pathways in trigeminal autonomic cephalalgias. The ipsilateral autonomic features suggest cranial parasympathetic activation (lacrimation, rhinorrhoea, nasal congestion and eyelid oedema) and sympathetic hypofunction (ptosis and miosis). Some authors have suggested that the pathophysiology of the trigeminal autonomic cephalalgias revolves around the trigeminal autonomic reflex (2). There is considerable experimental animal literature to document that stimulation of trigeminal efferents can result in cranial autonomic outflow. In fact, some degree of cranial autonomic symptomatology is an abnormal response to cranial nociceptive input and patients with other headache syndromes may report these symptoms. The distinction between the trigeminal autonomic cephalalgias and other headache syndromes is the degree of autonomic activation (5).
Because head pain is conveyed mostly by the trigeminal nerve, any region innervated by trigeminal nerves could hypothetically trigger a headache. Recently, the trochlear area has been described as an unrecognized trigger point in some migraineurs with trochleitis and a new type of headache, primary trochlear headache, has also been described (3, 6). This type of headache is an painful intraorbital, extraocular disorder with the maximum pain located in the inner–upper part of the orbit. Several mechanical ancillary features, such as examination of the involved trochlea or vertical eye movements, exacerbate pain, which is relieved by injecting lidocaine or corticosteroids on the sore trochlea.
Frequently, primary trochlear headache is associated with other types of headache such as chronic migraine, episodic migraine or tension-type headache. In the latter, myofascial trigger points in the superior oblique muscle and the presence of a myofascial disorder in the trochlear region have been described which may contribute to its pathogenesis (7). Primary trochlear headache may increase the nociceptive output toward the caudalis trigeminal nuclei, thus contributing to a possible central sensitization and perpetuating the course of the symptoms in migraineurs (8). Treatment of primary trochlear headache would relieve such cells from the excessive input, thus decreasing their firing rate. The association with chronic paroxysmal hemicrania has not been previously described. However, the good response of this patient suggests that intervention in the trochlear region could be useful in chronic paroxysmal hemicrania and other types of headache in which the pain is referred to the orbital region. The trochlea should be examined carefully in every patient complaining of orbital pain or headache, especially when adequate control of pain has not been achieved with conventional therapy.