Makindo Medical Notes

⚡ 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

• Neurology – New TN Classification
• BMJ Group: Trigeminal Neuralgia