Guillain-Barré syndrome

Definition

Guillain-Barré syndrome (GBS) is an acute, immune-mediated polyradiculoneuropathy characterized by rapidly progressive, symmetrical muscle weakness, typically starting in the lower limbs and ascending proximally, often with areflexia. It is the most common cause of acute flaccid paralysis worldwide.

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Etiology and Triggers

Common triggers (preceding infections or events) – occur in ~2/3 of patients 1–4 weeks before onset:

• Campylobacter jejuni gastroenteritis (most common bacterial trigger)

• Viral infections: cytomegalovirus, Epstein–Barr virus, Zika virus, HIV, influenza

• Vaccinations (rare, small risk reported with some influenza vaccines)

• Surgery

• Mycoplasma pneumoniae infection

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Pathophysiology

• Autoimmune cross-reactivity: Antibodies generated against microbial antigens cross-react with gangliosides on peripheral nerve membranes (molecular mimicry).

• This causes segmental demyelination (in acute inflammatory demyelinating polyneuropathy – AIDP) or axonal degeneration (in acute motor axonal neuropathy – AMAN, and acute motor-sensory axonal neuropathy – AMSAN).

• Nerve conduction is slowed or blocked, impairing motor and sensory function.

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Clinical Features

Typical presentation

• Symmetrical weakness beginning in legs → ascends to arms, face, respiratory muscles

• Weakness progresses over hours to days; maximal within 2–4 weeks

• Reduced or absent deep tendon reflexes

• Sensory symptoms: paresthesias, numbness (usually mild compared to motor weakness)

• Cranial nerve involvement: facial weakness, bulbar palsy

• Autonomic dysfunction: tachycardia/bradycardia, blood pressure fluctuations, urinary retention, constipation, sweating abnormalities

Variants

• Miller Fisher syndrome: triad of ophthalmoplegia, ataxia, areflexia; often anti-GQ1b antibody positive

• AMAN/AMSAN: more severe axonal injury, poorer recovery prognosis

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Red Flags for Urgent Attention

• Rapid progression of weakness (hours–days)

• Dyspnea or reduced vital capacity (<20 mL/kg)

• Dysphagia or difficulty handling secretions

• Severe autonomic instability (arrhythmias, hypotension/hypertension)

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Diagnosis

Clinical: Symmetrical, progressive weakness with areflexia and recent infection history is strongly suggestive.

Investigations:

• Nerve conduction studies (NCS)/electromyography (EMG): Demyelinating pattern (slowed conduction velocities, prolonged distal latencies) or axonal changes

• Lumbar puncture: Classic finding – albuminocytologic dissociation (elevated CSF protein with normal or near-normal white cell count) after the first week

• Blood tests: Exclude differential diagnoses (vitamin deficiencies, electrolyte imbalances, myopathies)

• Antiganglioside antibodies: GM1 (AMAN), GQ1b (Miller Fisher variant)

• Spirometry: Monitor vital capacity and negative inspiratory force for respiratory failure risk

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Differential Diagnosis

• Acute transverse myelitis

• Myasthenia gravis

• Botulism

• Tick paralysis

• Poliomyelitis

• Periodic paralysis syndromes

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Management

All patients require hospital admission – even mild cases can progress rapidly to respiratory failure.

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1. Supportive Care

• Admit to facility with capability for respiratory monitoring and ventilatory support

• Monitor vital capacity at least every 4–6 hours in evolving cases

• Manage airway, provide oxygen, mechanical ventilation if indicated

• Cardiac monitoring for autonomic instability

• Thromboprophylaxis: Low-molecular-weight heparin if immobile

• Pressure area care, prevention of contractures (physiotherapy)

• Nutritional support, bladder and bowel management

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2. Specific Immunotherapy

Initiate as early as possible (within 2–4 weeks of onset) in patients unable to walk independently:

• Intravenous immunoglobulin (IVIG): 0.4 g/kg/day IV for 5 consecutive days

  • Preferred for ease of administration and in children

  • Watch for renal impairment, thrombotic events

• Plasma exchange (plasmapheresis): 4–6 exchanges over 1–2 weeks

  • Equally effective as IVIG

  • Removes pathogenic antibodies and complement

Do not combine IVIG and plasma exchange – no added benefit and increased risk

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3. Medications to Avoid

• Corticosteroids: Not effective in altering the course of GBS when used alone

• Neuromuscular blocking agents unless necessary for ventilation – increased sensitivity in GBS

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Prognosis

• Most patients begin to recover within 2–4 weeks after progression stops

• ~80% achieve independent walking at 6 months

• Mortality ~3–7%, usually from respiratory failure or autonomic complications

• Poor prognostic factors: Older age, rapid progression, need for ventilation, severe axonal degeneration on NCS

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Possible Complications

• Respiratory failure

• Severe autonomic dysfunction → arrhythmias, blood pressure instability

• Persistent weakness or sensory deficits

• Chronic pain and fatigue

• Psychological impact and depression