Guillain-Barré syndrome
Summary
Guillain-Barré syndrome (GBS) is an acute, inflammatory demyelinating polyneuropathy causing ascending muscle weakness and areflexia. It's typically triggered by infections (especially Campylobacter jejuni) and involves molecular mimicry leading to autoimmune peripheral nerve damage. CSF shows cytoalbuminous dissociation (elevated protein, normal cell count).
Detail
Guillain-Barré syndrome is an acute autoimmune polyneuropathy characterized by progressive, ascending muscle weakness beginning in the lower extremities. The pathophysiology involves molecular mimicry where antibodies produced against infectious agents cross-react with peripheral nerve components, particularly myelin and axons. Common triggers include Campylobacter jejuni (most common), CMV, EBV, and Zika virus. The classical presentation includes symmetric weakness starting distally and progressing proximally over days to weeks, accompanied by areflexia and sensory symptoms. Respiratory muscle involvement can be life-threatening, requiring mechanical ventilation in 20-30% of cases. Diagnosis is supported by nerve conduction studies showing demyelination, and CSF analysis revealing cytoalbuminous dissociation (protein >400 mg/dL with <10 cells/μL). Treatment involves plasma exchange or IVIG, both equally effective. Most patients recover completely, though 10-20% have residual deficits. Miller Fisher syndrome is a variant characterized by the triad of ophthalmoplegia, ataxia, and areflexia.
Sources
- First Aid for the USMLE Step 1
- Harrison's Principles of Internal Medicine
- Adams and Victor's Principles of Neurology
- UpToDate Clinical Decision Support
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