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Guillain-Barré syndrome (GBS)
Guillain-Barré syndrome is an acute immune attack on the peripheral nerves, usually after an infection, presenting as ascending symmetric weakness with absent reflexes that peaks within 4 weeks — and the immediate dangers are respiratory failure and autonomic instability.
Why it matters in the exam
The classic scenario is a young adult two weeks after diarrhoea or a respiratory infection, with tingling feet, back pain and weakness climbing over days, and absent reflexes. The tests check CSF findings (high protein with few cells — which may be normal in the first week), the electrical study, treatment (IVIG or plasma exchange, not steroids), and above all when to admit to intensive care and ventilate. Common distractors: excluding GBS because the CSF is normal on day three, giving steroids, combining IVIG and plasma exchange, or relying on oxygen saturation. The Miller Fisher variant presents with ophthalmoplegia, ataxia and areflexia, with GQ1b antibodies. Most patients improve over weeks to months, but some are left with residual weakness.
Key points
- GBS is symmetric ascending weakness with absent reflexes, usually after an infection.
- Peak within 4 weeks; the CSF shows high protein with few cells.
- Treatment: IVIG 0.4 g/kg daily for 5 days or plasma exchange; not steroids.
- Monitor vital capacity and ventilate below 20 mL/kg.
- Miller Fisher: ophthalmoplegia, ataxia and areflexia with GQ1b antibodies.
Summary table
| Topic | Finding or rule | Note |
|---|---|---|
| Presentation | Symmetric ascending weakness, absent reflexes, tingling and back pain, bilateral facial palsy | Peak within 4 weeks; progression beyond 8 weeks fits CIDP |
| Preceding triggers | Campylobacter (axonal form), CMV, EBV, Zika, rarely after vaccination | In the axonal form (AMAN) GM1 antibodies |
| Diagnosis | CSF: raised protein and few cells (under 50 per cubic millimetre); nerve conduction study | Many cells in the fluid suggest another diagnosis (HIV, Lyme, malignancy) |
| Treatment | IVIG 0.4 g/kg daily for 5 days, or plasma exchange; IVIG within 2 weeks of weakness onset, plasma exchange up to 4 weeks | Steroids are not effective; do not give the two treatments in sequence |
| Monitoring and support | Serial vital capacity; intubate below 20 mL/kg; monitor heart rhythm and blood pressure; VTE prevention; pain control | Swallowing difficulty, weak neck flexion and rapid progression predict ventilation |
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Sources
- EAN/PNS Guideline on Diagnosis and Treatment of Guillain-Barré Syndrome, 2023 — Diagnosis, immunotherapy and supportive care
- Brighton Collaboration Case Definition of Guillain-Barré Syndrome, 2011 — Diagnostic certainty levels
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.