Guillain-Barré syndrome is an autoimmune disorder that affects the nerves. Autoimmune disorders occur when the immune system malfunctions and attacks the body's own tissues and organs. In Guillain-Barré syndrome, the immune response damages peripheral nerves, which are the nerves that connect the central nervous system (the brain and spinal cord) to the limbs and organs. Specifically, the immune response affects a particular part of peripheral nerves called axons, which are the extensions of nerve cells (neurons) that transmit nerve impulses. Guillain-Barré syndrome can affect the neurons that control muscle movement (motor neurons); the neurons that transmit sensory signals such as pain, temperature, and touch (sensory neurons); or both. As a result, affected individuals can experience muscle weakness or lose the ability to feel certain sensations.

Muscle weakness or paralysis are the characteristic features of Guillain-Barré syndrome. The weakness often begins in the legs and spreads to the arms, torso, and face and is commonly accompanied by numbness, tingling, or pain. Additional signs and symptoms of the condition include difficulty swallowing and difficulty breathing. Occasionally, the nerves that control involuntary functions of the body such as blood pressure and heart rate are affected, which can lead to fluctuating blood pressure or an abnormal heartbeat (cardiac arrhythmia).

There are several types of Guillain-Barré syndrome, classified by the part of the peripheral nerve involved in the condition. The most common type of Guillain-Barré syndrome is acute inflammatory demyelinating polyradiculoneuropathy (AIDP). In AIDP, the immune response damages myelin, which is the covering that protects axons and promotes the efficient transmission of nerve impulses. In two other types of Guillain-Barré syndrome, acute motor axonal neuropathy (AMAN) and acute motor-sensory axonal neuropathy (AMSAN), the axons themselves are damaged by the immune response. In AMAN, only the axons of motor neurons are damaged. In AMSAN, the axons of sensory neurons are also damaged. Because of sensory nerve damage, affected individuals can lose the ability to sense the position of their limbs and can have abnormal or absent reflexes (areflexia).

Miller Fisher syndrome, another type of Guillain-Barré syndrome, involves cranial nerves, which extend from the brain to various areas of the head and neck. Miller Fisher syndrome is characterized by three features: weakness or paralysis of the muscles that move the eyes (ophthalmoplegia), problems with balance and coordination (ataxia), and areflexia. People with this condition can have other signs and symptoms common in Guillain-Barré syndrome, such as muscle weakness.

Guillain-Barré syndrome occurs in people of all ages. The development of the condition usually follows a pattern. Prior to developing the condition, most people with Guillain-Barré syndrome have a bacterial or viral infection. The first phase of Guillain-Barré syndrome, during which signs and symptoms of the condition worsen, can last up to four weeks, although the peak of the illness is usually reached in one to two weeks. During the second phase, called the plateau, signs and symptoms of Guillain-Barré syndrome stabilize. This phase can last weeks or months. During the recovery phase, symptoms improve. However, some people with Guillain-Barré syndrome never fully recover and can still experience excessive tiredness (fatigue), muscle weakness, or muscle pain.

Guillain-Barré syndrome (GBS) is a rare neurological disorder in which your immune system mistakenly attacks part of the 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 you 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.

GBS can increase in intensity over a period of hours, days, or weeks until certain muscles cannot be used at all and, when severe, the person is almost totally paralyzed. In these cases, the disorder is life-threatening—potentially interfering with breathing and, at times, with blood pressure or heart rate.

The prevalence of Guillain-Barré syndrome is estimated to be 6 to 40 cases per 1 million people. The occurrence of the different types of Guillain-Barré syndrome varies across regions. AIDP is the most common type in North America and Europe, accounting for approximately 90 percent of cases of Guillain-Barré syndrome in those regions. AMAN and AMSAN together account for 30 to 50 percent of cases in Asian countries and Latin America but only 3 to 5 percent of cases in North America and Europe. Miller Fisher syndrome is also more common in Asian countries, accounting for approximately 20 percent of cases in these countries but less than 5 percent in North America and Europe.

GBS 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. It is not contagious or inherited.

The exact cause of GBS isn't known. Researchers don't know why it strikes some people and not others.

What they do know is that the affected person's immune system begins to attack the body itself. It may be this immune attack starts as a fight against 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.

Many of the body's nerves are like household wires. There is a central conducting core in the nerves called the axon that carries an electric signal. The axon (an extension of a nerve cell) is surrounded by a covering, like insulation, called myelin. The myelin sheath surrounding the axon speeds up the transmission of nerve signals and allows the transmission of signals over long distances.

In most cases of GBS, the immune system damages the myelin sheath that surrounds the axons of many peripheral nerves; however, it also may also damage the axons themselves. As a result, the nerves cannot transmit signals efficiently and the muscles begin to lose their ability to respond to the brain's commands. This causes weakness.

Most GBS 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 (there have been reports of a few people who received a vaccine for the SARS-CoV-2 virus developing GBS, but the chance of this occurring is very low). Some countries worldwide reported an increased incidence of GBS following infection with the Zika virus.

Guillain-Barré syndrome (GBS) is a rare disorder where the body’s immune system damages nerve. The damage to the nerves causes muscle weakness and sometimes paralysis. While its cause is not fully understood, the syndrome often follows infection with a virus or bacteria. Each year in the United States, an estimated 3,000 to 6,000 people develop GBS. Most people fully recover from GBS, but some have permanent nerve damage.

GBS is rare.

Anyone can develop GBS, but people older than 50 are at greatest risk. About two-thirds of people with GBS were sick with diarrhea or respiratory illness days or weeks before developing symptoms. Infection with the bacteria Campylobacter jejuni, which causes gastroenteritis (including symptoms of nausea, vomiting and diarrhea), is one of the most common risk factors for GBS. People also can develop GBS after having the flu or other infections such as cytomegalovirus and Epstein-Barr virus. On very rare occasions, people develop GBS in the days or weeks after getting a vaccination.

To study whether a new vaccine might be causing GBS, CDC compares the usual rate of GBS to the observed rate of GBS in vaccinated people. This helps to determine whether a vaccine could be causing more cases.

GBS and the link to flu vaccine

In response to a potential pandemic strain of a flu virus in 1976, there was a national campaign for people to get the swine flu vaccination. Over 45 million people were vaccinated and there were increased reports of GBS following vaccination. Those who received the 1976 swine flu vaccine had a slight increased risk for developing GBS of approximately one additional case of GBS for every 100,000 people who got the swine flu vaccine. Scientists have several theories about the cause, but the exact reason for this link remains unknown.

CDC monitors GBS cases during each flu season. From data collected, the association between seasonal flu vaccine and GBS has been found to vary from season to season. When there has been an increased risk, it has consistently been in the range of 1-2 additional GBS cases per million flu vaccine doses administered.

Additional studies have been conducted on the risk of GBS following flu vaccination. Results of these studies suggest that it is more likely that a person will get GBS after getting the flu than after vaccination. It is important to keep in mind flu infection can potentially cause severe illness and death. The best way to prevent flu infection and its complications is to get the flu vaccine.

Almost all cases of Guillain-Barré syndrome are sporadic, which means they occur in people with no history of the condition in their family. A few families with more than one affected family member have been described; however, the condition does not have a clear pattern of inheritance. Multiple genetic and environmental factors likely play a part in determining the risk of developing this condition. As a result, inheriting a genetic variation linked with Guillain-Barré syndrome does not mean that a person will develop the condition.

Weakness—The weakness seen in GBS usually comes on quickly and worsens over hours or days. Symptoms are usually equal on both sides of the body (called symmetric). You may first notice weakness as difficulty climbing stairs or with walking. Symptoms often affect the arms, breathing muscles, and even the face, reflecting more widespread nerve damage. Occasionally symptoms start in the upper body and move down to the legs and feet. Muscles controlling breathing can weaken to the point that you might need a machine to help you breathe.

Most people reach the greatest stage of weakness within the first two weeks after symptoms appear; by the third week 90 percent of affected individuals are at their weakest.

Sensation changes—Since nerves are damaged in GBS, your brain may receive abnormal sensory signals from the rest of your body. This results in unexplained, spontaneous sensations, called paresthesias, that you may feel as tingling, a sense of insects crawling under the skin (called formications), and pain. Deep muscular pain may be experienced in the back and/or legs.

Unexplained sensations often occur first, such as tingling in the feet or hands, or even pain (especially in children), often starting in the legs or back. Children will also show symptoms with difficulty walking and may refuse to walk. These sensations tend to disappear before the major, longer-term symptoms appear. 

Other symptoms may include:

• Difficulty with eye muscles and vision
• Difficulty swallowing, speaking, or chewing
• Pricking or pins and needles sensations in the hands and feet
• Pain that can be severe, particularly at night
• Coordination problems and unsteadiness
• Abnormal heartbeat/rate or blood pressure
• Problems with digestion and/or bladder control

The initial signs and symptoms of GBS are varied and there are several disorders with similar symptoms. Therefore, doctors may find it difficult to diagnose GBS in its earliest stages and may perform the following tests.

• Physical exam—Your physician will look at your physical symptoms, ask about your medical history, and conduct exams to assess how your muscles and nerves are functioning. Your physician or a specialist will note whether your symptoms appear on both sides of the body (the typical finding in Guillain-Barré syndrome) and the speed with which the symptoms appear (in other disorders, muscle weakness may progress over months rather than days or weeks). Your reflexes also will be checked: in GBS, deep tendon reflexes in the legs, such as knee jerks, are usually lost. Reflexes may also be absent in the arms.
• Nerve conduction velocity test (NCV)—This test measures the nerve's ability to send a signal. In GBS, the signals traveling along the damaged nerves are slow and this can provide clues to aid the diagnosis.
• Cerebrospinal fluid analysis—Your doctor also may remove and have analyzed a small sample of the cerebrospinal fluid that bathes the spinal cord, since the fluid in people with GBS contains more protein than usual but very few immune cells (measured by white blood cells).

Key diagnostic findings include:

• Recent onset, within days to at most four weeks of symmetric weakness, usually starting in the legs
• Abnormal sensations such as pain, numbness, and tingling in the feet that accompany or even occur before weakness
• Absent or diminished deep tendon reflexes in weak limbs
• Elevated cerebrospinal fluid protein without elevated cell count. This may take up to 10 days from onset of symptoms to develop.
• Abnormal nerve conduction velocity findings, such as slow signal conduction
• Sometimes, a recent viral infection or diarrhea.

There is no known cure for Guillain-Barré syndrome. However, some therapies can lessen the severity of the illness and shorten your recovery time. There are also several ways to treat the complications of the disease.

If you have GBS, you are usually admitted to and treated in hospital's intensive care unit due to possible complications of muscle weakness, problems that can affect any paralyzed person (such as pneumonia or bed sores), and the need for sophisticated medical equipment.

Acute care

There are currently two treatments commonly used to interrupt immune-related nerve damage. Both are equally effective if started within two weeks of GBS symptoms.

• Plasma exchange (PE), also called plasmapheresis, involves removing some of your blood through a catheter. The blood cells from the liquid part of the blood (plasma) are extracted and treated and returned to your body. Plasma contains antibodies and PE removes some plasma; PE may work by removing the bad antibodies that have been damaging the nerves.
• Intravenous immunoglobulin therapy (IVIg) involved intravenous injections of immunoglobulins—proteins that your immune system naturally makes to attack infecting organisms. The immunoglobulins are developed from a pool of thousands of healthy donors. IVIg can lessen the immune attack on the nervous system and shorten recovery time. Investigators believe this treatment also lowers the levels or effectiveness of antibodies that attack the nerves by both “diluting” them with non-specific antibodies and providing antibodies that bind to the harmful antibodies and take them out of commission.

Anti-inflammatory steroid hormones called corticosteroids have also been tried to reduce the severity of GBS, but controlled clinical trials showed this treatment is not effective.

Supportive care is very important to address the many complications of paralysis as your body recovers, and damaged nerves begin to heal. Since respiratory failure can occur in GBS, your breathing should be closely monitored. Sometimes a mechanical ventilator is used to help support or control breathing. The autonomic nervous system (that regulates the functions of internal organs and some of the muscles in your body) can also be disturbed, causing changes in heart rate, blood pressure, toileting, or sweating, so you should be put on a heart monitor or equipment that measures and tracks body function. You also may need help with any difficulty from secretions in the mouth and throat. In addition to choking and/or drooling, secretions can fall into your airway and cause pneumonia.

Rehabilitative care

As you begin to improve, you may be transferred from the acute care hospital to a rehabilitation setting. Here, you can regain strength, receive physical rehabilitation and other therapy to resume activities of daily living, and prepare to return to pre-illness life. 

Because GBS can affect several parts of your body, you may need different methods and approaches to prevent or treat complications. For example, you may need a physical therapist to manually move and position your limbs to help keep the muscles flexible and prevent muscle shortening. Injections of blood thinners can help prevent dangerous blood clots from forming in leg veins. Inflatable cuffs may also be placed around your legs to provide intermittent compression. All or any of these methods helps prevent blood stagnation and sludging (the buildup of red blood cells in veins), which could lead to reduced blood flow in the leg veins. Muscle strength may not return uniformly; some muscles that get stronger faster may tend to take over a function that weaker muscles normally perform—called substitution. A physical therapist can select specific exercises to improve the strength of weaker muscles so their original function can be regained.

Occupational and vocational therapy helps you learn new ways to handle everyday functions that may be affected by the disease, as well as work demands and the need for assistive devices and other adaptive equipment and technology.

Guillain-Barré syndrome can be a devastating disorder because of its sudden and rapid, unexpected onset of weakness—and usually actual paralysis. Fortunately, most people with GBS have a full recovery. With careful intensive care and successful treatment of infection, autonomic dysfunction and other medical complications, even those individuals with respiratory failure usually survive.

Your recovery can be slow or incomplete–anywhere from as little as a few weeks up to a few years. Some individuals still report ongoing improvement after two years. About 30 percent of those with Guillain-Barré have residual weakness after three years. About three percent may suffer a relapse of muscle weakness and tingling sensations many years after the initial attack. About 15 percent of individuals experience long-term weakness; some may require ongoing use of a walker, wheelchair, or ankle support. Muscle strength may not return uniformly.

Ongoing fatigue, pain, and other annoying sensations can sometimes be troublesome. You may face physical difficulties and emotionally painful periods. You might find it extremely difficult to adjust to sudden paralysis and dependence on others for help with routine daily activities. Some people with GBS need psychological counseling to help them adapt. Support groups can often ease emotional strain and provide valuable information.