Guillain-Barré Syndrome
Acute immune-mediated ascending demyelinating polyneuropathy; can cause respiratory failure.
Also known as: GBS, Guillain-Barré, acute inflammatory demyelinating polyneuropathy, AIDP, Miller Fisher syndrome
Overview
Acute, immune-mediated, predominantly demyelinating polyradiculoneuropathy causing rapidly progressive symmetric weakness, areflexia, and variable sensory and autonomic involvement. Most common subtype in Western countries is acute inflammatory demyelinating polyneuropathy (AIDP); axonal subtypes (AMAN, AMSAN) more common in Asia. Miller Fisher syndrome variant: ophthalmoplegia + ataxia + areflexia, associated with anti-GQ1b antibodies.
Epidemiology
Incidence ~1-2 per 100,000 per year. Affects all ages; slight male predominance. Most common cause of acute generalized weakness in developed countries.
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Risk factors
- Antecedent infection (~2/3 of cases, 1-4 weeks before onset):
- Campylobacter jejuni (most common; associated with AMAN axonal variant and anti-GM1 antibodies)
- Cytomegalovirus
- Epstein-Barr virus
- Mycoplasma pneumoniae
- Influenza
- Zika virus
- SARS-CoV-2 (associations reported)
- Vaccinations (rare; modest signal historically with swine flu 1976; small risk with some vaccines)
- Surgery, malignancy (rare)
Pathophysiology
Molecular mimicry: antibodies generated against pathogen surface antigens cross-react with epitopes on peripheral nerve myelin (gangliosides — GM1, GD1a, GQ1b). Complement activation and macrophage-mediated demyelination produce conduction block. Axonal subtypes target the nodes of Ranvier and axolemma directly. Resolves over weeks-months as nerve remyelinates.
Clinical presentation
Symptoms
- Symmetric ascending weakness beginning in the legs, progressing over hours to days (peak by 2-4 weeks)
- Distal paresthesias and pain (often missed by clinicians but very common — back pain especially)
- Areflexia or hyporeflexia (key feature)
- Cranial nerve involvement in ~50% — bilateral facial weakness, dysphagia, dysarthria
- Respiratory muscle weakness — 25% require mechanical ventilation
- Autonomic dysfunction: tachy/bradyarrhythmias, BP swings, ileus, urinary retention
- Miller Fisher variant: ophthalmoplegia, ataxia, areflexia (anti-GQ1b)
Signs / physical exam
- Symmetric weakness, often distal>proximal initially, progressing to flaccid paralysis
- Decreased or absent deep tendon reflexes
- Mild distal sensory loss; rarely sensory level
- Bilateral facial weakness (peripheral CN VII pattern)
- Respiratory: tachypnea, paradoxical breathing, decreased forced vital capacity (NIF/MIP)
- Autonomic instability
Classic findings
Acute ascending symmetric weakness + areflexia + antecedent infection + albuminocytologic dissociation in CSF (elevated protein with normal cell count).
Differential diagnosis
- Spinal cord compression / transverse myelitis — Sensory level, bowel/bladder early, upper motor neuron signs — MRI spine mandatory
- Myasthenia gravis — Fatigability, ocular/bulbar predominance, normal reflexes, AChR antibodies; not ascending
- Botulism — Descending paralysis, dilated pupils, dry mucous membranes (anticholinergic effect on autonomic nerves), recent home-canned food or honey (infants)
- Tick paralysis — Tick attached; rapid recovery after removal
- Lyme disease (Bannwarth syndrome) — Painful radiculopathy, facial palsy, erythema migrans history
- Acute intermittent porphyria — Abdominal pain, neuropsychiatric symptoms, dark urine, low motor function
- Critical illness polyneuropathy/myopathy — Develops in ICU patients with sepsis/multiorgan failure
- Heavy metal toxicity (lead, thallium, arsenic) — Subacute course, sensory >> motor, exposure history
- Toxic neuropathies / drug-induced — Vincristine, isoniazid, statins; medication history
Diagnostic workup
Diagnostic criteria
Clinical: progressive symmetric weakness + areflexia, peak by 4 weeks, exclusion of alternative causes. Supportive: CSF albuminocytologic dissociation, electrodiagnostic features of demyelination.
Labs
- CBC, BMP, LFTs, ESR, CRP, HIV, HBV, HCV
- Antiganglioside antibodies (anti-GM1, anti-GD1a, anti-GQ1b — Miller Fisher)
- Stool for Campylobacter (low yield, usually cleared by presentation)
- Heavy metal screen if exposure history
- Pulmonary function: bedside NIF (negative inspiratory force) and FVC every 4-8 h; intubate if FVC <20 mL/kg, NIF less negative than -30 cm H2O, or MEP <40 cm H2O ('20/30/40 rule')
Imaging
- MRI spine with gadolinium — exclude compressive lesion; nerve root enhancement (especially cauda equina) supports GBS
- Nerve conduction studies / EMG: slowed conduction velocities, prolonged distal latencies, conduction block, F-wave abnormalities (early), low amplitudes (axonal variants)
- Lumbar puncture: albuminocytologic dissociation (elevated protein, normal WBC <5 cells/μL) — may be normal in first week; cell count >50 suggests alternate diagnosis (HIV, sarcoid, lymphomatous infiltration)
Diagnostic algorithm
| Feature | GBS | Myasthenia Gravis | Botulism |
|---|---|---|---|
| Pattern | Ascending symmetric | Fatigable, ocular/bulbar | Descending |
| Reflexes | Decreased/absent (early) | Normal | Decreased |
| Pupils | Normal (autonomic instability) | Normal | Dilated, sluggish |
| Antecedent | Infection 1-4 wk prior | Insidious | Canned food, honey (infants) |
| CSF | ↑ protein, normal cells | Normal | Normal |
| EMG | Demyelinating, conduction block | Decremental on repetitive stim | Incremental on rapid repetitive stim |
| Treatment | IVIG or PLEX (not steroids) | Pyridostigmine, immunosuppression | Antitoxin, supportive |
Treatment
First-line
- ICU admission for any patient with autonomic instability, bulbar weakness, or rapidly progressive disease
- Frequent pulmonary monitoring (FVC, NIF q4-8h); intubate at 20/30/40 thresholds — do not wait for hypoxia
- IVIG 0.4 g/kg/day × 5 days (total 2 g/kg) — first-line, equivalent efficacy to PLEX, easier to administer
- Plasma exchange (plasmapheresis) — 5 exchanges over 1-2 weeks; alternative first-line
- Combining IVIG and PLEX provides NO additional benefit
- Corticosteroids are NOT effective and may be harmful — do not use
- Supportive: DVT prophylaxis, pain control (gabapentin, opioids — neuropathic pain common), bowel/bladder care, pressure ulcer prevention, PT/OT
Second-line / adjunct
- Treat autonomic dysfunction: cautious BP management (avoid sudden drops), pacemaker pads available for bradyarrhythmias
- Nutrition: NG/PEG if dysphagia
- Psychological support (locked-in syndrome possible during peak)
- Long inpatient rehab often required
- Most patients improve over weeks-months; ~80% walk independently by 6 months
Complications
- Respiratory failure requiring mechanical ventilation (~25%)
- Autonomic dysfunction with fatal arrhythmias
- DVT/PE from immobility
- Pneumonia (aspiration, ventilator-associated)
- Decubitus ulcers
- Chronic pain (persistent in some patients)
- Residual weakness in ~20% at one year
- Mortality 3-5%, mostly from respiratory or autonomic complications
- Recurrence rare (~3%); persistent worsening >8 weeks → consider CIDP
PANCE pearls
- Loss of reflexes early is a defining feature — preserved reflexes argues against GBS.
- Albuminocytologic dissociation: elevated CSF protein with normal cell count. Pleocytosis (>5-10 WBC) should make you reconsider GBS — think HIV, Lyme, sarcoid, lymphomatous meningitis.
- 20/30/40 rule for intubation: FVC <20 mL/kg, NIF less negative than -30, or MEP <40 cm H2O.
- Steroids do NOT work in GBS — use IVIG or PLEX.
- Miller Fisher variant: ophthalmoplegia + ataxia + areflexia + anti-GQ1b antibodies. Usually self-limited.
- Persistent or progressive weakness >8 weeks moves the diagnosis to CIDP — which DOES respond to steroids.
References
- AAN 2003 / 2012 update — Practice Parameter: Immunotherapy for Guillain-Barré Syndrome (Hughes et al., Neurology 2003; reaffirmed)
- GBS Consensus — Diagnosis and Management of Guillain-Barré Syndrome — International Consensus Guideline (Leonhard et al., Nat Rev Neurol 2019)
- Cochrane IVIG — Intravenous Immunoglobulin for Guillain-Barré Syndrome (Hughes et al., Cochrane Database 2014)
- Brighton Criteria — Guillain-Barré Syndrome and Variants — Brighton Collaboration Case Definitions (Sejvar et al., Vaccine 2011)
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