Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of skeletal muscles of the body. Symptoms depend on the group of muscles involved, the most common are eye movements, facial expression, speech, chewing and swallowing. They will also be affected muscles that control breathing, movements of the limbs and neck. The repetition of the muscular activity weakens the muscle. The rest allows recovery. Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles.