Guillain-Barré syndrome is typically preceded by what type of event?

• A. An infection
• B. Trauma
• C. Surgery
• D. Vaccination

Answer: (A)

Guillain-Barré syndrome is an autoimmune attack on the peripheral nerves that is classically triggered by an infection. After a gastrointestinal illness (most often Campylobacter jejuni) or other recent infections, the immune response generates antibodies that cross-react with nerve components (molecular mimicry), leading to inflammation and demyelination of peripheral nerves. This produces the typical rapidly progressive, symmetric weakness with reduced or absent reflexes, usually beginning about 1–3 weeks after the infection. While trauma, surgery, or vaccines can be associated in rare cases, an antecedent infection is the most common and characteristic trigger.