No one yet knows why Guillain-Barré strikes some people and not others or 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.
Guillain-Barré is called a syndrome rather than a disease because it is not clear that a specific disease-causing agent is involved.
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. Reflexes such as knee jerks are usually lost.