Myasthenia gravis is a disease that causes weakness in your voluntary muscles. These are the muscles that you control. For example, you may have weakness in the muscles for eye movement, facial expressions, and swallowing. You can also have weakness in other muscles. This weakness gets worse with activity, and better with rest.
Myasthenia gravis is an autoimmune disease. Your body’s immune system makes antibodies that block or change some of the nerve signals to your muscles. This makes your muscles weaker.
Other conditions can cause muscle weakness, so myasthenia gravis can be hard to diagnose. Tests used to make a diagnosis include blood, nerve, muscle, and imaging tests.
With treatment, the muscle weakness often gets much better. Medicines can help improve nerve-to-muscle messages and make muscles stronger. Other drugs keep your body from making so many abnormal antibodies. These medicines can have major side effects, so they should be used carefully. There are also treatments which filter abnormal antibodies from the blood or add healthy antibodies from donated blood. Sometimes, surgery to take out the thymus gland helps.
Some people with myasthenia gravis go into remission. This means that they do not have symptoms. The remission is usually temporary, but sometimes it can be permanent.
NIH: National Institute of Neurological Disorders and Stroke
Congenital myasthenic syndrome is a group of conditions characterized by muscle weakness (myasthenia) that worsens with physical exertion. The muscle weakness typically begins in early childhood but can also appear in adolescence or adulthood. Facial muscles, including muscles that control the eyelids, muscles that move the eyes, and muscles used for chewing and swallowing, are most commonly affected. However, any of the muscles used for movement (skeletal muscles) can be affected in this condition. Due to muscle weakness, affected infants may have feeding difficulties. Development of motor skills such as crawling or walking may be delayed. The severity of the myasthenia varies greatly, with some people experiencing minor weakness and others having such severe weakness that they are unable to walk.Some individuals have episodes of breathing problems that may be triggered by fevers or infection. Severely affected individuals may also experience short pauses in breathing (apnea) that can lead to a bluish appearance of the skin or lips (cyanosis).