Etiology of Guillain-Barré Syndrome
Guillain-Barré syndrome is caused by an aberrant autoimmune response triggered by preceding infections in approximately 75% of cases, with Campylobacter jejuni being the single most common infectious trigger, responsible for about one-third of all GBS cases 1, 2.
Infectious Triggers
The pathophysiology centers on molecular mimicry between surface structures of pathogens and components of peripheral nerve myelin or axolemma 2. The most common infectious agents include:
- Campylobacter jejuni (most frequent, ~33% of cases) - typically causes more severe GBS presentations 2
- Cytomegalovirus
- Epstein-Barr virus
- Mycoplasma pneumoniae
- Haemophilus influenzae 3
The clinical presentation and severity directly correlate with the structure of pathogenic lipo-oligosaccharides (LOS) from these organisms, which trigger innate immunity via Toll-like-receptor-4 signaling 2.
Immunopathological Mechanism
The disease results from autoantibodies directed against gangliosides and other nerve components 1. Approximately 60% of patients have detectable glycolipid antibodies produced through molecular mimicry 4. Recent evidence suggests cell-mediated immunity also plays a role in pathogenesis 4.
The autoimmune attack manifests differently based on the target:
- AIDP (Acute Inflammatory Demyelinating Polyradiculoneuropathy): Demyelination of peripheral nerves
- AMAN/AMSAN (Acute Motor Axonal Neuropathy variants): Direct axolemmal damage at nodal or internodal spaces 2
Important Clinical Context
GBS incidence increases during infectious disease outbreaks, as demonstrated during the 2013 Zika virus epidemic in French Polynesia and 2015 Latin America outbreak 1. This infection-triggered pattern explains why GBS remains the leading global cause of acute flaccid paralysis with an incidence of 1-2 per 100,000 person-years 1.
Key Caveat
While infections account for three-quarters of cases, the remaining 25% have no identifiable trigger, and the complete pathogenesis remains incompletely understood 1.