Guillain-Barré syndrome, or GBS, is believed to be an autoimmune
disorder in which the body creates antibodies against its own
tissue. In people with GBS, the antibodies generally attack the
myelin sheath, or lining of the nerves. They may also attack
part of the nerves themselves. Guillain-Barré syndrome is
thought to be an autoimmune disorder that is triggered by an
infection, vaccination, or other factors. It causes a severe
inflammatory reaction around the nerves. The myelin sheath
becomes swollen. Impulses and messages cannot travel along the
course of the nerve. In time, nerve impulses are blocked. Most
cases of Guillain-Barré syndrome are triggered by an infection.
Two-thirds of the individuals with GBS have had an upper
respiratory infection or gastrointestinal infection 1 to 3 weeks
before weakness develops. Other infections that may trigger GBS
include: Some vaccinations may also trigger Guillain-Barré
syndrome. These include: Certain medicines have been identified
as triggers for GBS. These include