What is Guillain-Barre syndrome?
It is a disorder in which the body's immune system attacks part of the nervous system. The first symptoms of this disorder include varying degrees of weakness or tingling sensations in the legs. In many instances the weakness and abnormal sensations spread to the arms and upper body. These symptoms can increase in intensity until the muscles cannot be used at all and the patient is almost totally paralyzed. In these cases the disorder is life threatening -- potentially interfering with blood pressure, heart rate, and breathing -- and is considered a medical emergency. The patient is often put on a respirator to assist with breathing and is watched closely for problems such as an abnormal heart beat, infections, blood clots, and high or low blood pressure. Most patients, however, recover from even the most severe cases of Guillain-Barr??e syndrome, although some continue to have minor problems.
Guillain-Barre syndrome can affect anybody. It can strike at any age and both sexes are equally prone to the disorder. The syndrome is rare, however, afflicting only about one person in 100,000. Usually Guillain-Barre occurs a few days or weeks after the patient has had symptoms of a respiratory or gastrointestinal viral infection. Occasionally pregnancy, surgery, or vaccinations will trigger the syndrome. The disorder can develop over the course of hours or days, or it may take up to 3 to 4 weeks. Most people reach the stage of greatest weakness within the first 2 weeks after symptoms appear, and by the third week of the illness 90 percent of all patients are at their weakest.
What causes Guillain-Barre syndrome?
No one yet knows why Guillain-Barre strikes some people and not others. Nor does anyone know exactly what sets the disease in motion. What scientists do know is that the body's immune system begins to attack the body itself, causing what is known as an autoimmune disease. Usually the cells of the immune system attack only foreign material and invading organisms. In Guillain-Barre syndrome, however, the immune system starts to destroy the myelin sheath that surrounds the axons of many nerve cells, or even the axons themselves (axons are long, thin extensions of the nerve cells; they carry nerve signals). The myelin sheath surrounding the axon speeds up the transmission of nerve signals and allows the transmission of signals over long distances.
In diseases in which the nerve cells' myelin sheaths are injured or degraded, the nerves cannot transmit signals efficiently. That is why the muscles begin to lose their ability to respond to the brain's commands, commands that must be carried through the nerve network. The brain also receives fewer sensory signals from the rest of the body, resulting in an inability to feel textures, heat, pain, and other sensations. Alternately, the brain may receive inappropriate signals that result in tingling, "crawling-skin," or painful sensations. Because the signals to and from the arms and legs must travel the longest distances they are most vulnerable to interruption. Therefore, muscle weakness and tingling sensations usually first appear in the hands and feet.
When Guillain-Barre is preceded by a viral infection, it is possible that the virus has changed the nature of cells in the nervous system so that the immune system treats them as foreign cells. It is also possible that the virus makes the immune system itself less discriminating about what cells it attacks. Scientists are investigating these possibilities and others to find why the immune system goes awry in Guillain-Barre syndrome and other autoimmune diseases. The cause and course of Guillain-Barre syndrome is an active area of neurological investigation, incorporating the cooperative efforts of neurological scientists, immunologists, and virologists.
How is Guillain-Barre syndrome diagnosed?
Guillain-Barre is called a syndrome r