Guillain-Barre syndrome is a serious disorder that occurs when the body's defense (immune) system mistakenly attacks part of the nervous system. This leads to nerve inflammation that causes muscle weakness.

Guillain-Barre syndrome is an autoimmune disorder (the body's immune system attacks itself). Exactly what triggers Guillain-Barre syndrome is unknown. The syndrome may occur at any age, but is most common in people of both sexes between ages 30 and 50.

It often follows a minor infection, usually a lung infection or gastrointestinal infection. Usually, signs of the original infection have disappeared before the symptoms of Guillain-Barre begin.

Guillain-Barre syndrome causes inflammation that damages parts of nerves. This nerve damage causes tingling, muscle weakness, and paralysis. The inflammation usually affects the nerve's covering (myelin sheath). Such damage is called demyelination. Demyelination slows nerve signaling. Damage to other parts of the nerve can cause the nerve to stop working.

Guillain-Barre syndrome may occur along with viral infections such as:

• AIDS
• Herpes simplex
• Mononucleosis

It may also occur with other medical conditions such as systemic lupus erythematosus or Hodgkin's disease.

Some people may get Guillain-Barre syndrome after a bacterial infection or certain vaccinations (such as rabies and swine flu). A similar syndrome may occur after surgery, or when critically ill.