Description

• A group of acquired autoimmune disorders causing acute peripheral neuropathy
• Subtypes classified by pattern of neural injury:
  • Acute inflammatory demyelinating polyradiculoneuropathy (AIDP):
    • Accounts for ~95% of cases in Europe and North America
    • Progressive limb weakness with areflexia
  • Axonal injury: Accounts for about 5% of cases in Europe and North America, but 30–47% of cases in China, Japan, and Central and South America
  • Acute motor axonal neuropathy (AMAN): Pure motor neuropathy
  • Acute motor-sensory axonal neuropathy (AMSAN): Combined motor–sensory neuropathy; poor prognosis

• In Guillain-Barré syndrome (GBS) symptoms progress for up to 4 weeks. This distinguishes it from subacute and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), in which the onset phase lasts 4–8 weeks or >8 weeks, respectively.
• Synonym(s): GBS, acute inflammatory demyelinating polyneuropathy; Landry-Guillain-Barré-Strohl syndrome; Acute inflammatory polyneuropathy; Idiopathic polyneuritis; Acute autoimmune neuropathy; Landry ascending paralysis

ALERT
25–30% of patients have respiratory paralysis. Rapidly progressive forms may cause quadriplegia and a need for mechanical ventilation within 48 hours.

Absent reflexes are a red flag for GBS in patients with rapidly progressive limb weakness.

A history of weakness preceded by respiratory or GI infection suggests GBS.

Epidemiology

Incidence
In the US: 1.8/100,000 (0.8/100,000 in children <18 years of age; 3.2/100,000 in adults >60 years of age)

• In the US: 3–10/100,000
• Male > Female (1.5:1)

Risk Factors

Of patients with GBS, ⅔ have a history of a preceding GI (especially Campylobacter jejuni), respiratory (especially influenza), or sinus infection.

Pathophysiology

Autoimmune disorder targeted against myelin and/or axons causing destruction of peripheral nerves in susceptible individuals

Etiology

Leading hypothesis is that pathogenesis involves molecular mimicry (i.e., invoking an immune response to antigenic targets that are coincidentally shared by infectious organisms and peripheral nerve tissue).

Commonly Associated Conditions

• 2/3 of cases associated with antecedent bacterial or viral infection, usually of the respiratory or GI tract:
  • C. jejuni: The most common precipitant of GBS, seen in 21–32% of cases:
    • Associated with axonal degeneration, slower recovery, more severe residual disability
  • Cytomegalovirus (CMV): Primary CMV infection precedes 10–22% of cases
  • Also associated with Mycoplasma pneumoniae (5%), influenza, Epstein-Barr virus (EBV), varicella zoster virus, and HIV infections
• Influenza vaccinations:
  • Risk of GBS following influenza infection 40–70× greater than risk following seasonal influenza vaccine
  • Based on 1992–1994 data, inactivated seasonal flu vaccines are associated with a marginally significant, very small increase in the risk of GBS equivalent to about 1 case/million vaccines above background incidence. A steady decline seen in the number of cases of GBS associated with influenza vaccine in the US between 1993–1994 (0.17 per 100,000 vaccinations) and 2002–2003 (0.04 per 100,000).
  • Following the immunization campaign against influenza A (H1N1) in Quebec, Canada, the relative risk for any GBS from the vaccine was 3.02, relative to those who were unvaccinated: ~2 cases of GBS per 1 million doses attributable to the vaccine. The authors concluded that the benefits of vaccination likely outweigh the risks (1).
  • Of historical importance: Increased incidence during 1976 US national immunization program against swine-origin influenza A H1N1 subtype A/NJ/76; vaccine-attributable risk 8.8 per million recipients