What is Guillain-Barré Syndrome?
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 fibres (axons) and sometimes damages the fibres themselves. Thus there are both axonal and demylinating subtypes of GBS.The 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 start in the hands and feet and move progressively upward, affecting both sides of the body. GBS is a medical emergency and 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, but it is the most common acquired inflammatory neuropathy and the most common causes of acute paralysis. According to the National Institute of Neurological Disorders and Stroke (NINDS), about 1 person in 100,000 will have GBS. It can affect anyone at any age but it increases in incidence with age and there is a small predominance of males. Sensory symptoms in the legs usually mark the onset of the disease followed by rapidly progressive distal weakness that soon spreads proximally. It is an unusual neuropathy in that it spontaneously reverses, and most patients recover most or all of the lost nerve and muscle function.
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. Infections are recognised as being important in triggering GBS and GBS is considered an immunological response to these. Antibodies against peripheral nerve gangliosides (sugar molecules) are recognised as an important mechanism of nerve damage. Many cases have been linked with a viral or bacterial infection that occurs a week or two before GBS develops. 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). Studies have shown that Campylobacter jejuni, Epstein Bar virus, and Cytomegalovirus are the most frequent triggering infections. Something happens during these infections that 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.
Signs and symptoms can progress relatively quickly once they appear. They typically start in the feet and/or hands and spread upward to the legs, arms and trunk. At first they may include:
- Tingling or pins-and-needle sensations
- Numbness
- Tenderness
- Weakness, especially in the legs
- Muscle spasms
- Loss of coordination
- Loss of reflexes
More serious symptoms, some of which may require emergency medical assistance, include:
- Paralysis
- Difficulty breathing and/or swallowing
- Abnormal heart rate
In most cases, symptoms develop over hours to days and may continue to worsen for up to a month, after which they slowly resolve. Up to 30% of those affected may still have some lingering weakness after 3 years, and a small percentage may have a relapse years later.
Patient history is important in diagnosis. The progression of ascending paralysis – starting with feet or hands and advancing upward – is a typical presentation. About 50% of cases also include a history of a recent mild infection or illness like a sore throat, a cold, the flu, or diarrhoea. Several tests are commonly used to diagnose or confirm the disease and, sometimes, to monitor recovery.
- Cerebrospinal fluid (CSF) analysis – to identify the presence of increased protein; for this test, a needle is inserted into the spine between vertebrae and a small amount of fluid is withdrawn. While some protein is normally present, an increased amount without an increase in the white blood cells in the CSF may be indicative of Guillain Barré syndrome.
- Nerve conduction velocity – tests the speed at which impulses travel through a nerve; the nerve conduction velocity test uses electrodes placed on the skin over peripheral nerves and measures the amount of time it takes for an impulse to travel between electrodes.
- Electromyography (EMG) – measures the electrical activity of muscles fibres; the EMG test measures the electrical activity within muscle fibres by placing a needle electrode through the skin directly into the muscle and measuring the electrical activity of that muscle. It is usually done in conjunction with a nerve conduction velocity test.
There are several variants of GBS that are associated with specific signs and symptoms and with the production of different types of antibodies directed against gangliosides. Ganglioside autoantibody tests are particularly useful in helping to distinguish these disorders, the most common autoantibodies being anti-GQ1B and anti-GM1. These are specialised tests and are performed within Immunology laboratories.
Other testing may be performed to help distinguish GBS from other causes of weakness, neuropathy, and immune dysfunction and to monitor the person's health status during illness and recovery.
Guillain-Barré syndrome usually resolves on its own. In most cases, symptoms will stabilise and then begin to resolve within weeks or months. The goals of treatment are to try to help decrease the severity of symptoms, speed healing, and to prevent and/or minimse complications. Many people with GBS require hospitalisation for careful monitoring and supportive care. If the symptoms are severe, the person may require breathing assistance.
Two approaches are sometimes used early in the disease to lessen the severity and hasten the recovery. Both are intended to decrease the effectiveness of the antibodies that attack the myelin sheath. Plasmaphoresis, a process of removing blood, filtering out the liquid plasma that contains antibodies that may be involved in the autoimmune disorder, and then returning the red and white blood cells to the circulation, has proven effective in some people. Immunoglobulin injections to block the activity of the damaging antibodies have also been shown to be beneficial to some people.
In the recovery phase, most of those with GBS will need to undergo physical therapy to help regain muscle strength.