Season 2 Episode 17: Multiple Sclerosis is a potentially disabling disease of the brain and spinal cord (central nervous system). In MS, the immune system attacks the protective sheath (myelin) that covers nerve fibers and causes communication problems between your brain and the rest of your body. Eventually, the disease can cause permanent damage or deterioration of the nerves, resulting in the loss of the ability to walk independently, or at all, loss of muscle use and numbness and tingling of extremities.