SUNCT and SUNA: rare short-lasting headache disorders explained

SUNCT and SUNA are two named forms of a single group of primary headache disorders. The International Classification of Headache Disorders, third edition (ICHD-3), describes the group as attacks of moderate or severe, strictly one-sided head pain lasting seconds to minutes, occurring at least once a day and usually associated with prominent tearing and redness of the eye on the same side.

ICHD-3 recognises two subtypes. SUNCT is short-lasting unilateral neuralgiform headache attacks with conjunctival injection (eye redness) and tearing. SUNA is the same with other cranial autonomic symptoms, such as nasal congestion or a runny nose, eyelid swelling, forehead and facial sweating or flushing, or a drooping eyelid. ICHD-3 notes that SUNCT may be a subform of SUNA, though this needs further study, so the two are often discussed together.

They are classified as primary headaches, meaning they are not caused by another illness, although a specialist will want to exclude secondary causes, particularly when attacks begin for the first time.

ICHD-3 describes pain that is moderate or severe, on one side, around the eye, above the eye or in the temple, lasting from 1 to 600 seconds and occurring as single stabs, a series of stabs or a saw-tooth pattern. OUCH (UK), the cluster headache charity, gives a typical attack duration for SUNCT of 15 to 120 seconds and says attacks can occur up to 30 times per hour.

The accompanying features are on the same side as the pain. ICHD-3 lists eye redness or tearing, nasal congestion or runny nose, eyelid swelling, forehead and facial sweating or flushing, a feeling of fullness in the ear, and a smaller pupil or drooping eyelid. At least one of these must be present for the diagnosis. Attacks can be triggered, and ICHD-3 notes SUNCT and SUNA can usually be triggered without a refractory period, that is, without a pause after each attack, which helps to separate them from trigeminal neuralgia.

The sheer frequency is what makes the condition so disruptive. A person may have dozens of attacks in a day, which affects sleep, concentration, work and mood.

Cluster headache is the best-known relative. The NHS describes cluster headaches as severe headaches that can happen multiple times a day and continue for weeks or months, with pain usually on one side around the eye lasting between 15 minutes and 3 hours, and often a red, watering eye. SUNCT and SUNA attacks are much shorter and often more frequent.

Trigeminal neuralgia is the other main look-alike. The NHS describes it as sudden, severe facial pain, like an electric shock, lasting from a few seconds to about 2 minutes, usually felt in the lower part of the face and triggered by light touch such as washing, eating or brushing teeth. SUNCT and SUNA pain is more often felt around the eye and forehead and is accompanied by prominent eye and nasal symptoms.

Because these conditions overlap, and because the correct treatment differs, a specialist assessment matters. Self-diagnosis from a list of features is unreliable.

There is no single blood test. Diagnosis rests on a detailed history and the ICHD-3 criteria, which require at least 20 attacks of the typical pattern. The NHS makes the same point for cluster headache, saying there are no specific tests and that a GP will ask about the pain, location and frequency, and may refer to a specialist for a brain scan to rule out other possible causes.

A specialist may request an MRI scan of the brain to look for a structural cause, particularly when the headaches are new. A neurologist may also ask you to keep a diary of attack numbers, timing and triggers, which helps both diagnosis and judging treatment response.

Treatment is specialist-led. OUCH (UK) says SUNCT headache was until recently thought to be very difficult to treat, but partial improvement with carbamazepine has been observed in several people. It says lamotrigine has been reported to be effective among a small number of sufferers, with gabapentin and topiramate thought to be reasonable second-line agents if that fails, and that several surgical techniques may also be considered.

This is a small evidence base, and these are medicines used for other conditions, so decisions are made case by case by a neurologist. Whether the treatments used for cluster headache, such as triptans or oxygen, are of any use for such brief attacks is a specialist decision, which is a key reason the diagnosis needs to be right. The NHS notes for cluster headache that painkillers such as paracetamol and ibuprofen do not work.

Medicines such as carbamazepine and lamotrigine need gradual dose changes and monitoring, so do not start, stop or change them without specialist advice.

Any first severe headache, or a sudden change in pattern, deserves prompt assessment. The NHS says to call 999 or go to A&E if you have a drooping eyelid or a pupil that is smaller than the other for the first time, even if you have already been diagnosed with cluster headaches. It also says to get an urgent GP appointment or call 111 for 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 can be symptoms of temporal arteritis.

If you have attacks like those described here, see your GP, who can refer you to a neurologist. Support is available from OUCH (UK), which also covers related headaches.

Because attacks are so brief, frequent and unpredictable, people often describe being exhausted and anxious about the next one. A headache diary, pacing activities, protecting sleep and talking to your employer about reasonable adjustments can help. NICE CKS says that cluster headache can have a significant impact on quality of life including work, home and relationships, and prolonged severe symptoms can affect mental health. The same is true here, so tell your GP if low mood or hopelessness develop.

Because these are rare, you may find it takes time to reach the right diagnosis. Bringing a clear attack diary and a description of the eye and nose symptoms to the appointment is the most useful preparation.