In myasthenia gravis, the immune system attacks the receptors in muscles that receive nerve signals, resulting in muscle weakness.
The condition is sometimes associated with a tumor of the thymus (an immune gland in the neck).
Symptoms may include drooping eyelids, double vision, slurred speech, difficulty chewing and swallowing, weakness in the legs and arms, and breathing difficulty.
Treatment may include medication to improve transmission of nerve signals, immunosuppressants, and sometimes surgery to remove the thymus.
If symptoms suddenly become severe, urgent medical treatment is needed.