Guillain-Barre Syndrome (GBS)

Definition

• Annual incidence: 1.8 per 100,000 (stable over 30 years)
• Male:Female ratio: 1.5:1
• Incidence increases with age (0.8/100,000 under 18 years vs. 3.2/100,000 over 60 years)

Pathophysiology

• Injury is most extensive at nerve roots and proximal nerve segments
• Associated with mononuclear cell infiltrates rich in macrophages
• Classic finding: multifocal inflammatory demyelination of spinal roots and peripheral nerves

Precipitating Infections / Triggers

Subtypes and Variants

• AIDP (Acute Inflammatory Demyelinating Polyradiculoneuropathy) - most common in Europe/North America
• AMAN (Acute Motor Axonal Neuropathy) - prevalent in northern China (summer epidemics in children); pure motor
• AMSAN (Acute Motor-Sensory Axonal Neuropathy) - severe, poor recovery

• Miller-Fisher Syndrome (MFS) - triad of ophthalmoplegia, ataxia, areflexia; anti-GQ1b antibodies; 6% of GBS in Western countries, up to 18% in Taiwan
• Pharyngeal-cervical-brachial variant
• Facial diplegia with paresthesias
• Paraparetic variant
• Acute pandysautonomia

Clinical Features

Classic Presentation

• Ascending weakness - starts in lower limbs, spreads proximally over hours to days, may involve arms, face, oropharynx, and respiratory muscles
• Areflexia or hyporeflexia (universal, though may be absent early)
• Paresthetic sensory symptoms, often worse in hands and fingers
• Progression to nadir: 2-4 weeks

Cranial Nerve Involvement (45-75% of cases)

• Bilateral facial palsy in at least 50% of patients
• Extraocular muscle involvement (less common)

Respiratory Failure

• Occurs in 9-30% of hospitalized patients
• Risk increases with age

Sensory Symptoms

• Sensory loss is NOT prominent
• Distal vibration sense impairment
• Pain in 70% - extremities, interscapular, or back - may persist for 1 year in a third of patients

Autonomic Dysfunction (65% of hospitalized patients)

• Occurs predominantly in the first 2-4 weeks (peak paralysis)
• Manifestations: orthostatic hypotension, urinary retention, GI atony, episodic hypertension/hypotension, sinus tachycardia, tachyarrhythmias, anhidrosis/diaphoresis
• Excessive vagal activity can cause: sinus arrest, bradycardia (triggered by tracheal suctioning, Valsalva maneuver, or defecation)

Diagnostic Criteria

1. Progressive weakness of both legs AND arms
2. Areflexia or hyporeflexia

• Progression over days to 4 weeks
• Relative symmetry
• Mild sensory symptoms
• Bifacial palsies
• Autonomic dysfunction
• Absence of fever at onset
• Recovery beginning 2-4 weeks after progression ceases

• Elevated CSF protein with <10 cells/μL (albuminocytological dissociation)
• Electrodiagnostic features: nerve conduction slowing or block

Electrophysiology

• AIDP: prolonged distal latencies, slow conduction velocities, conduction blocks, prolonged F-waves, reduced or absent H-reflexes
• AMAN/AMSAN: low-amplitude CMAPs (axonal pattern), preserved conduction velocities
• Serial EDX studies may be needed as early studies can be normal

Differential Diagnosis

Treatment

• Plasmapheresis (PLEX) - removes offending antibodies; typically 5 exchanges over 10 days
• IV Immunoglobulin (IVIG) - 0.4 g/kg/day x 5 days; suppresses immune responses (mechanism not fully clear)
• Combination of both is NOT superior to either alone
• Corticosteroids are NOT recommended (shown to have no benefit and may delay recovery)

• Respiratory monitoring (FVC, NIF) - intubate if FVC <15-20 mL/kg
• Cardiac monitoring for arrhythmias
• DVT prophylaxis
• Pain management (gabapentin, carbamazepine)
• Bowel/bladder care

• A recent 2026 systematic review (PMID: 41038424) confirmed that physical exercise programs significantly improve fatigue and functional capacity in GBS patients in the recovery phase.

Prognosis

• Mortality: ~1-5% (down from 33% before positive-pressure ventilation)
• ~80% of patients are ambulatory at 6 months
• ~10-15% have residual disability
• Favorable prognostic factors: young age, slow progression, mild nadir disability, AIDP subtype
• Poor prognostic factors: older age, rapid onset, severe weakness, prior C. jejuni infection, AMSAN subtype, need for ventilation

Key Distinguishing Points for Exams