Guillain-Barré syndrome (GBS) is a rare neuromuscular condition in which nerve damage inhibits muscle movement. This loss of mobility is usually temporary, although its severity and duration can vary greatly from person to person. In a small number of cases, permanent paralysis or death may result.

GBS is considered an autoimmune disorder, where the body’s immune system attacks its own cells, causing tissue damage. In patients with GBS, this damage involves the nerves of the peripheral nervous system (those outside the brain and spinal cord).  

GBS affects the protective coating of nerves, the myelin sheath, and the nerve extensions called axons. The myelin sheath helps protect the nerve and speed transmission of signals between the brain and muscles. This aids motor functioning and physical coordination. The axons help conduct electrical impulses to other nerves, muscles and cells throughout the body.

GBS causes inflammation that can damage the nerves. Portions of the myelin sheath may be stripped away, reducing their ability to insulate and protect the axons. Myelin sheath damage of peripheral nerves can slow or prevent the nerves from transmitting signals between the brain and muscles. This causes the muscles to respond inefficiently, if at all. Likewise, the brain receives fewer signals from the nerves, resulting in the inability to feel certain sensations, or the experience of abnormal sensation. Because signals to the arms and legs must travel the farthest, they are more susceptible to interruption when nerve damage occurs. Damage to the axons can cause the nerves to stop working altogether and result in paralysis.

Nerve damage can cause a wide variety of symptoms such as paresthesia (burning or tingling in the hands or feet), numbness, weakness, paralysis that are common in patients with GBS. Symptoms usually begin in the lower extremities (e.g., legs) before spreading to the upper extremities (e.g., arms).

GBS affects only about one or two people out of every 100,000. The illness is known as a syndrome rather than a disease because scientists do not know whether or not a disease-causing agent is involved in the disorder. Thus, GBS is a medical condition characterized by a collection of certain signs and symptoms.

Complications of GBS may include lingering muscle weakness or long-term or permanent paralysis. If muscle weakness or paralysis associated with GBS spreads to the breathing muscles, a patient may experience respiratory failure. Significant damage may occur to the muscles and nerves, which can weaken the lungs and heart. This can result in a dangerous slowing of the heart rate and lowering of blood pressure.

GBS is fatal in about 5 percent of cases, according to the U.S. Centers for Disease Control and Prevention. Causes of death related to GBS may include respiratory failure, pulmonary embolism or cardiac arrest. Older adults are at the greatest risk of fatality. About 3 percent of patients who survive and recover from GBS may be prone to future relapse of the illness, according to the National Institutes of Health.