Trigeminal-Autonomic Cephalgias

Abstract

T he trigeminal autonomic cephalgias (TACs) are a group of primary headache disorders characterised by unilateral trigeminal distribution pain that occurs in association with prominent ipsilateral cranial autonomic features.1 The group comprises cluster headache, paroxysmal hemicrania, hemicrania continua, and short lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT syndrome). Firstly, they must be differentiated from secondary TACs, and other short lasting primary headaches (table 1), and then from each other. The concept of a short lasting headache is naturally somewhat artificial in terms of defining "short"-that said, a typical attack time is less than four hours, in contrast with the major differential diagnosis of migraine in which attacks are usually longer.2 The differentiation between TACs is essential since the treatments are very different. Hemicrania continua is a continuous headache and should be considered in the differential diagnosis of relatively long lasting chronic daily headache (see page ii2). 3The TACs are relatively rare, which is likely to be why they are poorly recognised in primary care. TACs will thus be referred to neurologists eventually, offering an excellent opportunity to diagnose and treat these patients. It is noteworthy that each of the TACs has been seen in paediatric practice. The importance of recognising these syndromes is underscored by their excellent but highly selective response to treatment. c CLUSTER HEADACHECluster headache (CH) is a strictly unilateral headache that occurs in association with cranial autonomic features and, in most patients, has a striking circannual and circadian periodicity. It is an excruciating syndrome and is probably one of the most painful conditions known to humans. Female patients describe each attack as being worse than childbirth. EpidemiologyThe prevalence of CH is estimated to be 0.1%, 4 approximately the same as that of multiple sclerosis in the UK. The male:female ratio is 3.5-7:1. 5 6 It can begin at any age though the most common age of onset is the third or fourth decade of life. Clinical featuresIt is useful for both clinician and patient to standardise the terms used in CH. A cluster headache or an attack is an individual episode of pain that can last from a few minutes to some hours. A cluster bout or period refers to the duration over which recurrent cluster attacks are occurring; it usually lasts some weeks or months. A remission is the pain-free period between two cluster bouts. CH is a disorder with highly distinctive clinical features. These features are dealt with under two headings: the cluster attack and the cluster bout. The cluster attackThe attacks are strictly unilateral, though the headache may alternate sides. The pain is excruciatingly severe. It is located mainly around the orbital and temporal regions though any part of the head can be affected. The headache usually lasts 45-90 minutes but can range from 15 minutes to three hours. It has an abrupt onset and cessation....