Myasthenia gravis (say "MI-ess-thin-e-a GRAH-viss") is muscle weakness that often gets better when you rest and gets worse with activity. You can start the day feeling strong, but after a little activity, you find yourself feeling weak. It may be hard to talk or to keep your eyes focused, and your eyelids may droop.
This problem starts when the immune system attacks the body's own muscle cells. The immune system is supposed to fight off viruses and other germs, but sometimes it turns on the person's own body. (This is called autoimmune disease.) Myasthenia gravis most often affects the muscles that control eye and facial movement and those that help us chew and swallow.
Your doctor may prescribe medicine that can help improve your muscle weakness. The doctor may recommend that you have surgery to remove the thymus gland, which may improve your immune system problem and help you regain your strength. There are other treatments that can help if you have repeated periods of weakness. Some people have periods of time with mild or no symptoms. This is called remission.