Guillain-Barré Syndrome, GBS, is a rare autoimmune disorder that causes your immune system to attack your peripheral nervous system. When this happens, it is difficult for your nerves to transmit signals from your brain and spinal cord to the rest of your body. Your muscles may be the first areas affected, resulting in weakness or tingling in your legs and arms. If the condition spreads to your upper body, it can be life-threatening by impairing your ability to breathe. While the cause of GBS is unknown, it often occurs after a viral infection, and scientists now are beginning to study links to the Zika virus. Most people recover, but complete recovery can take as long as a few years.