Guillain-Barré syndrome (GBS) is a rare neurological disorder in which the body’s immune system mistakenly attacks part of its peripheral nervous system—the network of nerves located outside of the brain and spinal cord. GBS can range from a very mild case with brief weakness to nearly devastating paralysis, leaving the person unable to breathe independently. Fortunately, most people eventually recover from even the most severe cases of GBS. After recovery, some people will continue to have some degree of weakness.
Guillain-Barré syndrome can affect anyone. It can strike at any age (although it is more frequent in adults and older people) and both sexes are equally prone to the disorder. GBS is estimated to affect about one person in 100,000 each year.
The exact cause of GBS is not known. Researchers don’t know why it strikes some people and not others. It is not contagious or inherited.
What they do know is that the affected person’s immune system begins to attack the body itself. It is thought that, at least in some cases, this immune attack is initiated to fight an infection and that some chemicals on infecting bacteria and viruses resemble those on nerve cells, which, in turn, also become targets of attack. Since the body’s own immune system does the damage, GBS is called an autoimmune disease (“auto” meaning “self”). Normally the immune system uses antibodies (molecules produced in an immune response) and special white blood cells to protect us by attacking infecting microorganisms (bacteria and viruses). In Guillain-Barré syndrome, however, the immune system mistakenly attacks the healthy nerves.
Most cases usually start a few days or weeks following a respiratory or gastrointestinal viral infection. Occasionally surgery will trigger the syndrome. In rare cases vaccinations may increase the risk of GBS. Recently, some countries worldwide reported an increased incidence of GBS following infection with the Zika virus.