GPAtlas🧭 When to suspect
Suspect trigeminal neuralgia (TN) in a patient describing sudden, severe, strictly unilateral facial pain in the distribution of one or more divisions of the trigeminal nerve (V1 ophthalmic, V2 maxillary, V3 mandibular). The pain is characteristically brief – lasting seconds to around two minutes – and is described as sharp, shooting, stabbing or electric-shock-like, with abrupt onset and termination. The lower face is most often affected (V2 and V3); isolated V1 involvement is uncommon and should prompt a search for another cause.
The hallmark is triggering by innocuous stimuli within a cutaneous “trigger zone” – washing, shaving, brushing teeth, eating, talking, or a cold breeze on the face – typically followed by a brief refractory period during which the pain cannot be provoked. Between attacks the face is usually completely pain-free, although some patients develop a continuous dull background ache (TN with concomitant continuous pain).
The two clinical priorities in primary care are to recognise the pattern and to exclude a secondary cause. TN is classified by underlying aetiology, which shapes how strongly secondary pathology should be pursued.
| Classification | Underlying cause | Clinical pointer |
|---|---|---|
| Classical TN | Neurovascular compression of the nerve root with morphological change (usually the superior cerebellar artery) | The commonest form; neurological examination is normal |
| Secondary TN | Multiple sclerosis, posterior-fossa or cerebellopontine-angle tumour, arteriovenous malformation, skull-base lesion | Suspect if onset < 40, sensory loss, bilateral pain, or other neurological signs |
| Idiopathic TN | No cause identified on MRI or electrophysiology | A diagnosis of exclusion once secondary causes are ruled out |
Raise suspicion in patients over 50 (though any age is possible), with a slight female predominance. A younger age of onset, or any neurological deficit, shifts suspicion firmly towards a secondary cause.
Source: NICE CG173 · UK Trigeminal Neuralgia Guideline 2021
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