Myasthenia gravis interferes with messages your nerves send to your muscles. Myasthenia gravis often affects muscles in your head. Common symptoms are trouble with eye and eyelid movement, facial expression and swallowing. If you have myasthenia gravis, it is important to follow your treatment plan. If you do, you can expect your life to be normal or close to it. Myasthenia gravis is caused by a problem in the transmission of nerve signals to your muscles. Normally, nerve endings release a substance that attaches to receptors on your muscles. That tells your muscles to contract. If you have myasthenia gravis, your body's own immune system makes antibodies to block that signal. Medicine can help improve nerve-to-muscle messages and make muscles stronger. Other medicines can keep your body from making so many abnormal antibodies. Sometimes surgery to take out the thymus gland helps.