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Myasthenia gravis

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What does myasthenia gravis do to my body?

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What is myasthenia gravis?

Myasthenia gravis is a chronic autoimmune neuromuscular disease. It is characterized by varying degrees of weakness of the skeletal muscles of the body. Common symptoms include weakness of the muscles that control the eye and eyelid, facial expression, chewing, talking, and swallowing. Weakness tends to increase during periods of activity and improves after periods of rest.[1]
Last updated: 3/11/2009

What are the symptoms of myasthenia gravis?

Myasthenia gravis can affect any voluntary muscle. Voluntary muscles are the muscles that we directly control to make our body do things like walk, run, write, throw, lift, smile, and chew. In myasthenia gravis the most commonly affected muscles are the muscles that control eye and eyelid movement, facial expression, and swallowing. The degree of muscle weakness varies from person to person. People with more severe disease may have many muscles affected, including the muscles that control breathing. People with mild disease may have only one muscle group involved, such as the eye muscles.[1]

In general, signs and symptoms of myasthenia gravis may include a drooping of one or both eyelids (ptosis), blurred or double vision (diplopia), unstable or waddling gait, weakness in arms, hands, fingers, legs, and neck, a change in facial expression, difficulty in swallowing and shortness of breath, and impaired speech (dysarthria).[1]
Last updated: 3/11/2009

What causes myasthenia gravis?

Myasthenia gravis is caused by a defect in the communication of our nerves to our muscles. This error in communication is caused by our bodies own immune system which interferes with the normal communication between our nerves and muscles.[1] 

Our thymus gland plays an important role in the development of our immune system in early life. In adults with myasthenia gravis, the thymus gland is abnormal. Some people with myasthenia gravis develop thymomas or tumors of the thymus gland. Generally thymomas are not cancerous, but they can become so. The relationship between the thymus gland and myasthenia gravis is not yet fully understood, but it is thought that the abnormal thymus gland may be involved in creating the immune cells that interrupt the normal communication between our nerves and muscles.[1]
Last updated: 3/11/2009

How can I learn more about how myasthenia gravis affects my body?

MedlinePlus provides an interactive tutorial on myasthenia gravis that can aid you in better understanding the cause of myasthenia gravis and how it can affect your body. MedlinePlus is a Web site designed by the National Library of Medicine to help you research your health questions.

You can also use the navigation bar at the top of this page to view many additional resources on myasthenia gravis.
Last updated: 3/11/2009

See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.