Multiple sclerosis (MS) is a disease in which your immune system attacks the protective sheath (myelin) that covers your nerves. Myelin damage disrupts communication between your brain and the rest of your body. Ultimately, the nerves themselves may deteriorate, a process that's currently irreversible.
Signs and symptoms vary widely, depending on the amount of damage and which nerves are affected. Some people with severe MS may lose the ability to walk independently or at all, while others experience long periods of remission during which they develop no new symptoms.
There's no cure for multiple sclerosis. However, treatments can help speed recovery from attacks, modify the course of the disease and manage symptoms.