Trigeminal autonomic cephalalgias: cluster headache, paroxysmal hemicrania and SUNCT

The name describes the two features that unite the group. Trigeminal refers to the trigeminal nerve, which carries sensation from the face and head and is involved in the pain, and autonomic refers to the part of the nervous system that controls involuntary functions such as tear production and nasal secretions. People with these headaches typically have severe pain on one side of the head, around or behind the eye or in the temple, together with symptoms on the same side such as a red, watering eye or a blocked or runny nostril.

NHS Highland guidance groups cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks (including SUNCT, which stands for short-lasting unilateral neuralgiform headache with conjunctival injection and tearing, and SUNA, with cranial autonomic symptoms) and hemicrania continua together under this heading. Patient.info explains that the International Classification of Headache Disorders third edition moved cluster headache from migraine to the trigeminal autonomic cephalalgias.

All of the TACs are uncommon, and they are often mistaken for migraine, sinus problems, dental pain or trigeminal neuralgia. Recognising them matters, because the treatments differ from those used for migraine and because an ordinary painkiller usually fails.

The table summarises the definitions given in the NHS Highland guideline, which quotes the International Headache Society criteria. A specialist makes the diagnosis, and individual presentations can vary.

Because cluster headache is by far the best known, it shows the pattern of the group. The NHS describes cluster headaches as severe attacks of pain that can last for long periods, and says they are not caused by another illness. It lists a sharp, burning or piercing pain usually on one side of the head around the eye, attacks at the same time of year or at set times of the day, headaches that start and stop quickly without warning, pain that makes you restless so that you want to walk around, and headaches that last between 15 minutes and 3 hours. Other symptoms include a red and watering eye, feeling sick, a drooping and swollen eyelid, a smaller pupil, face sweating and a blocked or runny nose, all on the side of the pain.

NICE CKS says cluster headache attacks occur in series, usually lasting between 2 weeks and 3 months (cluster periods or bouts), and that 85 to 90% of cases are episodic and 10 to 15% chronic. The exact cause is complex and not fully understood. The NHS says it is not known what causes cluster headaches, that they are more common in men in their 30s and 40s or if a close family member gets them, and that triggers can include smoking, alcohol, perfume, the smell of paint, nail varnish or petrol, and exercise. NICE CKS notes that the headaches can significantly affect quality of life, including work and relationships, and that people with prolonged and severe symptoms may express suicidal thoughts, which is a reason to seek help early.

The NHS advice on cluster headaches is specific. Call 999 or go to A&E if you have either of these symptoms for the first time, even if you have already been diagnosed: one eyelid drooping, or the pupil in one eye smaller than the other. Get an urgent GP appointment or call NHS 111 if you have a severe headache with jaw pain when eating, blurred or double vision, a sore scalp, or numbness or weakness in the arms or legs, which could be symptoms of temporal arteritis.

NHS Highland guidance lists features of a headache that should prompt scanning or urgent assessment, including a worsening headache with fever, a sudden-onset headache reaching maximum intensity within 5 minutes, new neurological deficit, new cognitive dysfunction, impaired consciousness, a headache triggered by cough or exercise, a change in personality and a substantial change in the character of a headache. Any new, severe or unusual headache should be assessed rather than assumed to be a TAC.

The NHS says there are no specific tests to diagnose cluster headaches. A GP will ask about the pain, its location and frequency and any other symptoms, and may refer to a specialist for a brain scan to rule out other possible causes. NICE CKS advises specialist advice or urgent neurology referral for a suspected first bout of cluster headache to confirm the diagnosis, and referral to a neurologist where there is uncertainty about the diagnosis or atypical symptoms.

NHS Highland says that if a description fits paroxysmal hemicrania or hemicrania continua, a trial of indometacin should be given to see if the headache is eliminated, with a stomach-protecting medicine, and that if it is not effective it should be stopped and the person referred to a neurology clinic. The guideline notes that a complete response to indometacin is part of the definition of these two conditions. The doses and monitoring for this trial are for the prescribing clinician and are not something to try on your own.

Keeping a headache diary of the timing, length, side, associated symptoms and triggers helps a clinician tell the types apart, because duration and frequency are the main distinguishing features.

For cluster headache, the NHS says there is no cure but a specialist may recommend treatments to ease and prevent symptoms, and that painkillers such as paracetamol and ibuprofen do not work. Treatments for an attack that has started include triptans given as an injection or nasal spray, oxygen breathed through a mask, and a device that gives mild electrical pulses to the back of the neck. To prevent attacks the GP may prescribe corticosteroids, verapamil or lithium, and rarely surgery involving an implanted device is considered when other treatments have not worked. NICE CKS lists subcutaneous or intranasal triptans and short-burst high-flow 100% home oxygen for acute attacks, advises avoiding oral triptans or other oral analgesia for acute attacks, and says verapamil should be considered with specialist advice.

For paroxysmal hemicrania and hemicrania continua, indometacin is the treatment that defines the diagnosis, according to the NHS Highland guideline. SUNCT and SUNA are rarer, and the treatment is decided with specialist neurology input. Patient.info states that the realistic aim of treatment for cluster headache is suppression of the attack and reduction in frequency and severity, that drug treatment is always necessary for effective control and that there is no likely prospect, at present, of curative medical treatment.

These disorders can be disruptive because attacks come without warning, often at night, and cluster bouts can last weeks or months. NICE CKS notes that the natural history varies, but there may be less frequent bouts and longer remission periods as people get older. Practical steps include keeping a diary, avoiding known triggers such as alcohol during a bout, telling employers and family what to expect and asking about a written plan for what to do when an attack starts.

The NHS suggests contacting OUCH UK and The Migraine Trust for information, and a GP can help if low mood or anxiety develops. Because people with severe, prolonged symptoms can have suicidal thoughts, as NICE CKS highlights, it is important to tell someone if the pain feels unmanageable.

On the NHS the route is a GP assessment followed by neurology or a headache clinic. Private neurology consultations can offer faster appointments or imaging, and some people use them for a second opinion. Home oxygen, triptan injections and preventive medicines are specialist-guided on either route, so ask who will prescribe and monitor them. If you have a headache with red-flag features, do not wait for any appointment: seek urgent help as set out above.