⚡ Trigeminal Neuralgia (TN) → sudden, severe, paroxysmal facial pain lasting 30 sec–2 min. Often described as "electric shock-like" ⚡ and triggered by touch, chewing, or speaking. 💔 It is severely debilitating and can impact mental health.

📖 About

Neuropathic pain syndrome affecting the trigeminal nerve (CN V).
Classically unilateral, affecting one or more trigeminal divisions (V1, V2, V3).
Important to distinguish from secondary causes (e.g. multiple sclerosis, tumours).

📊 Epidemiology

Incidence: ~1 in 10,000/year.
Peak onset in 60s–70s 👵, women > men.
Rare <50 yrs → think of MS or secondary causes.

🧬 Aetiology

Microvascular compression (≈90%) – artery compresses nerve root → demyelination → ectopic firing.
Secondary TN: MS plaques, posterior fossa tumours, AVMs, cysts.

🧠 Anatomy Refresher

Origin: trigeminal root at lateral pons.
Sensory ganglion: Gasserian ganglion in Meckel’s cave.
Divisions: 👉 V1 (ophthalmic) – scalp, forehead, cornea 👉 V2 (maxillary) – mid-face, upper jaw 👉 V3 (mandibular) – lower jaw, tongue sensation, some motor

📌 Classification

Type 1 TN – purely paroxysmal, no pain between attacks.
Type 2 (Atypical) – constant dull background pain + paroxysms, harder to treat.

🩺 Clinical Features

Sudden unilateral, shock-like pain ⚡ (<2 min).
Trigger points: shaving 🪒, brushing teeth 🪥, eating 🍎, talking 💬, wind exposure 🌬️.
Autonomic: lacrimation, conjunctival injection, nasal congestion.
Psychological: anxiety, depression, sometimes suicidal ideation.

🧾 Differential Diagnosis

Multiple sclerosis (young onset, bilateral).
Posterior fossa tumours (CPA meningioma, acoustic neuroma).
AVMs, aneurysms.
Other cystic lesions (epidermoid, arachnoid).

🔎 Investigations

Routine bloods (FBC, U&E, ESR) → usually normal.
MRI Brain + trigeminal sequences: rule out MS, tumour, vascular compression.
Consider MR angiography for vessel–nerve relationships.

💊 Management

First-line: Carbamazepine 100 mg BD, ↑ by 100–200 mg every 2 wks. Usual effective: 200 mg TDS – 400 mg QDS. ⚠️ Monitor FBC & LFTs → risk of aplastic anaemia, liver toxicity.
Alternatives / Adjuncts: – Oxcarbazepine (better tolerated, fewer interactions). – Baclofen 10 mg TDS (esp. MS). – Lamotrigine, gabapentin, phenytoin in resistant cases.
Neurosurgical: – Microvascular decompression (gold standard in classic TN, durable relief). – Ablative: radiofrequency rhizotomy, gamma knife, glycerol rhizolysis.

🚩 Red Flags

Age <40 → think MS or tumour.
Bilateral pain.
Continuous pain without paroxysms (atypical, consider other pathology).
Associated neurological deficits (numbness, weakness).

📚 Exam Pearls

TN = shock-like pain, unilateral, triggered by touch.
First-line = carbamazepine (ask for FBC monitoring in OSCE).
Surgery (microvascular decompression) = most effective long-term.
In young → always rule out MS.

🔗 References

Cases — Trigeminal Neuralgia

Case 1 — Classic Idiopathic TN: A 55-year-old woman presents with sudden, severe, electric shock–like pains in her right cheek lasting seconds. Attacks are triggered by touching her face while washing. Neurological exam is normal. Diagnosis: Classical trigeminal neuralgia (likely due to vascular compression of CN V root). Management: First-line carbamazepine; consider MRI to rule out secondary causes.
Case 2 — Secondary TN from Multiple Sclerosis: A 35-year-old woman with relapsing-remitting multiple sclerosis presents with sharp, stabbing left-sided jaw pain, precipitated by chewing. Exam: decreased corneal reflex on the left. Diagnosis: Trigeminal neuralgia secondary to MS demyelinating plaque. Management: Carbamazepine or oxcarbazepine; optimise MS disease-modifying therapy; consider neurosurgical options if refractory.
Case 3 — Atypical TN from Tumour Compression: A 62-year-old man has progressively worsening unilateral facial pain with sensory loss in the V2 distribution. Pain is constant with superimposed shocks. MRI reveals a cerebellopontine angle mass compressing CN V. Diagnosis: Secondary trigeminal neuralgia due to tumour (vestibular schwannoma). Management: Refer to neurosurgery; analgesia for pain; definitive management by tumour resection/radiotherapy.

Teaching Commentary ⚡

Trigeminal neuralgia is characterised by paroxysmal, unilateral, severe facial pain lasting seconds–minutes, often triggered by light touch (allodynia). - Classical TN: vascular loop compression at nerve root entry zone. - Secondary TN: due to MS, tumours, vascular malformations. Red flags: sensory loss, bilateral symptoms, age <40 → investigate with MRI. First-line treatment = carbamazepine; alternatives include oxcarbazepine, lamotrigine, or baclofen. Refractory cases may need microvascular decompression or ablative procedures.

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Trigeminal Neuralgia