Guillain-Barré syndrome (GBS) is an acute condition associated with progressive muscle weakness and paralysis. It is an autoimmune disorder in which the body's immune system attacks its own nervous system. This causes inflammation that damages or destroys the myelin sheaths covering and insulating nerve fibers (axons) and sometimes damages the fibers themselves. This demyelination process slows or stops the conduction of impulses through the nerve, interfering with motor control and causing symptoms such as tingling or numbness that typically starts in the legs and moves to the arms, hands, and even the face. It often affects both sides of the body. GBS can be a medical emergency that must be closely monitored. Those affected may become so weak that they have trouble breathing and their heart rate may become abnormal.
Guillain-Barré syndrome is a relatively rare condition. According to the Centers for Disease Control and Prevention, an estimated 3,000 to 6,000 people develop GBS each year, affecting about 1 in 100,000 people. It can affect anyone at any age, although it is most common in older adults. It is an unusual neuropathy in that it spontaneously occurs, with recovery times varying from a few weeks to a few years.
The exact cause of GBS and why it affects one person and not another is not well understood. The autoimmune process may be spontaneous or may be triggered by some specific disease or exposure. About two-thirds of cases are linked with a viral or bacterial infection that causes diarrhea or a respiratory illness that occurs a week or two before GBS develops. One of the most common risk factors is an infection with the bacteria Campylobacter jejuni (about 40% of cases in the U.S. are thought to be triggered by this type of bacteria), but it may also be triggered by the flu or other viral infections such as cytomegalovirus, Epstein Barr virus, or Zika virus.
Cases have also been seen in people with HIV infection, in those with chronic diseases such as lupus (SLE), Hodgkin lymphoma (and some other malignancies), and rarely in those who have recently had a vaccination (such as for rabies or swine flu). Something in these circumstances leads to a change in the immune system's ability to discriminate between "self" and "non-self." Damage to the myelin sheath and nerve is thought to involve antibodies that mistakenly target these tissues.
According to the National Institute of Neurological Disorders and Stroke, some studies show there may be a genetic component to developing GBS, but more research is needed.