Synopsis
Differentiate cluster headache, paroxysmal hemicrania, SUNCT or SUNA and hemicrania continua by temporal pattern and indometacin response, while excluding structural mimics.
- Trigeminal autonomic cephalalgias combine strictly unilateral trigeminal-distribution pain with ipsilateral cranial autonomic activation or attack-related restlessness.
- Duration and frequency are the quickest discriminator: cluster lasts 15–180 minutes, paroxysmal hemicrania 2–30 minutes, and SUNCT or SUNA usually seconds to minutes.
- Paroxysmal hemicrania usually occurs more than five times daily and responds absolutely to adequate indometacin, making a supervised trial diagnostically important.
- SUNCT requires both ipsilateral conjunctival injection and tearing; SUNA has only one or neither of those two signs, although other cranial autonomic features occur.
- Hemicrania continua is continuous unilateral headache for over 3 months with exacerbations and an absolute response to indometacin, rather than a series of pain-free attacks.
- Short-lasting attacks can be triggered by touch or chewing and resemble trigeminal neuralgia, but prominent autonomic signs, longer refractory behaviour and attack pattern help distinction.
- Obtain headache-neurology input and specialist-directed MRI for a new TAC phenotype because pituitary, posterior-fossa, orbital and vascular lesions can imitate a primary syndrome.
- Do not group all TACs under cluster treatment: oxygen and sumatriptan, indometacin and lamotrigine belong to different syndrome-specific pathways.
- An indometacin test needs gastrointestinal, renal, cardiovascular and interaction assessment plus gastroprotection; casual low-dose exposure cannot exclude an indometacin-responsive headache.
Key red flags
Abnormal ocular movements, field loss, endocrine symptoms, persistent Horner syndrome, bilateral or changing signs, late atypical onset or incomplete syndrome raises concern for structural disease.
Investigation priorities
Capture untreated duration in seconds or minutes, attack number, continuous background pain, triggers and exact autonomic signs.
Management branches
Severe side-locked orbital or temporal pain occurs with cranial autonomic symptoms.
- Record untreated duration precisely, daily frequency, background pain, bout-remission pattern, triggers, restlessness and which autonomic signs occur on the pain side.
- Map minutes-to-hours attacks towards cluster, 2–30-minute high-frequency attacks towards paroxysmal hemicrania, seconds-to-minutes attacks towards SUNCT or SUNA, and continuous pain towards hemicrania continua.
- Examine eye, pupils and cranial nerves between attacks and screen for vascular, pituitary, orbital and posterior-fossa warning features.
- Refer for headache-neurology confirmation and appropriate imaging before committing to prolonged syndrome-specific therapy.
Key medicines
Indometacin diagnostic and preventive trialUse a headache-specialist titration to an adequate therapeutic exposure, then reduce to the lowest dose that maintains complete control if diagnosis is confirmed.High gastrointestinal, renal, cardiovascular and bleeding toxicity requires risk assessment, gastroprotection and monitoring; avoid casual unsupervised trials or combination with other NSAIDs.
LamotrigineStart at the specialist low dose and titrate slowly over weeks using the current BNF schedule and interaction-specific adjustments.Stop and seek urgent assessment for rash or systemic hypersensitivity; valproate greatly changes titration, and abrupt escalation increases severe cutaneous-reaction risk.