What causes Guillain-Barre syndrome?
The causes of Guillain Barre syndrome are unknown. Perhaps 50% of cases occur shortly after a microbial (viral or bacterial) infection such as a sore throat or diarrhea. Many researchers theorize that the autoimmune reaction in which macrophages and T-cells attack myelin in the peripheral and cranial nerves is associated with a bacteria or virus, as many cases occur a few days to a few weeks after an infection including the common cold, sore throat, and stomach and intestinal viruses with vomiting and diarrhea. The virus might induce the demyelination via a possible mimicry between the
effector virus and a human ganglioside. Normally, the cells of the immune system attack only foreign material and invading organisms, but in Guillain-Barre syndrome, the immune system starts to destroy the myelin sheath that surrounds the axons of many nerve cells, and sometimes the axons themselves.
The myelin sheath surrounding the axon speeds up the transmission of nerve signals and allows the transmission of signals over long distances. When they are injured or degraded, nerves cannot send signals efficiently, and muscles begin to lose their ability to respond to the brain's commands. And, 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. 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 and progress upwards.
If Guillain-Barre is preceded by a viral infection, it is possible that the virus changes the nature of cells in the nervous system causing the immune system to interpret them as foreign cells. It is also possible that the virus makes the immune system itself less discriminating about what cells it attacks. Sensitized T lymphocytes cooperate with B lymphocytes to produce antibodies against components of the myelin sheath and may contribute to destruction of the myelin. Scientists are investigating these and other possibilities to find why the immune system goes awry in Guillain-Barrè syndrome and other autoimmune diseases. The cause and course of Guillain-Barrè syndrome is an active area of neurological investigation, incorporating the cooperative efforts of neurological scientists, immunologists, and virologists.