Description

• A group of acquired autoimmune disorders causing acute peripheral neuropathy and ascending paralysis that progressively worsens for up to 4 weeks followed by a slow spontaneous recovery of function
• Subtypes classified by pattern of neural injury:
  • Acute inflammatory demyelinating polyradiculoneuropathy (AIDP): progressive limb weakness with areflexia (~95% of GBS cases in Europe and North America)
  • Axonal subtypes:
    • Acute motor axonal neuropathy (AMAN): pure motor neuropathy strongly associated with Campylobacter jejuni and a higher rate of respiratory failure (~5% of cases in Europe and North America but 30–47% of cases in China, Japan, and Central and South America)
    • Acute motor-sensory axonal neuropathy (AMSAN): combined motor-sensory neuropathy; poor prognosis with prolonged course
  • Regional subtypes:
    • Miller Fisher syndrome (MFS): triad with ophthalmoplegia, ataxia, and areflexia; antibodies to GQ1b present in 90% of patients with MFS
    • Bickerstaff encephalitis: possible variant of MFS with encephalopathy, ophthalmoplegia, ataxia, and hyperreflexia
    • Pharyngeal-cervical-brachial GBS: Parasympathetic and cholinergic dysfunction leads to neck, arm, and oropharyngeal weakness along with upper extremity areflexia.
  • Sensory subtypes:
    • Acute pandysautonomia: orthostatic hypotension, gastroparesis, ileus, constipation/diarrhea, sudomotor/pupillary abnormalities, and neuropathic pain
    • Acute sensory ataxic neuropathy (ASAN): controversial variant with sensory loss and ataxia
• Polyneuritis cranialis: bilateral cranial nerve involvement and severe peripheral sensory loss associated with cytomegalovirus (CMV) infections
• Synonym(s): GBS, AIDP; Landry-Guillain-Barré-Strohl syndrome, acute inflammatory idiopathic polyneuritis; acute autoimmune neuropathy; Landry ascending paralysis

Epidemiology

Incidence

• Most common acute paralytic disease in Western countries
• 0.6 to 2.0/100,000 worldwide
• U.S. incidence: 0.9 to 1.8/100,000
• Increases with age: 0.8/100,000 in children <18 years of age; 3/100,000 in adults >60 years
• 1.5 times higher incidence in males

Etiology and Pathophysiology

• Postinfectious autoimmune process targets Schwann cell surface membrane, myelin, and/or gangliosides causing peripheral nerve destruction and demyelination.
• Pathogenesis thought to involve molecular mimicry (i.e., an immune response to antigenic targets that are coincidentally shared by infectious organisms and host peripheral nerve tissue). Antibodies cross-react with GM1 myelin ganglioside with resultant damage to peripheral nervous system.

Genetics
Host factors appear to play a role in GBS, but no clear genetic risk has been identified.

Risk Factors

• COVID-19 vaccinations
  • A systematic review study showed a GBS rate of 1.8 to 53 cases per 1 million doses with the Pfizer, Johnson & Johnson, and Sinovac coronavirus vaccines.
• Influenza vaccinations
  • Inactivated seasonal flu vaccines associated with an increase in GBS risk equivalent to one case/million vaccines above background incidence (far less than the 17 cases of GBS per million people infected with influenza virus).
  • Incidence of GBS associated with flu vaccine decreasing over time with no increase detected in 2017 to 2018 season
  • Of historical note: Increased incidence during 1976 National H1N1 Immunization Program had vaccine-attributable risk of 8.8 per million recipients compared to 1.6 per million recipients in the 2009 H1N1 vaccination campaign.

Commonly Associated Conditions

Infection of the respiratory (22–53%) or gastrointestinal (GI) tract (6–26%) in preceding 6 weeks

• Campylobacter jejuni: most common precipitant of GBS, (21–40% of cases):
  • Associated with axonal degeneration, slower recovery, more severe residual disability
• CMV: Primary CMV infection precedes 10–22% of cases.
• Rarely associated with Mycoplasma pneumoniae, influenza infection, Epstein-Barr virus, varicella-zoster virus, HIV infection, zika virus, and some arboviral infections