A to Z: Myasthenia Gravis (MG)

Also called: myasthenia, MG, juvenile myasthenia gravis, JMG

What Is Myasthenia Gravis?

Myasthenia gravis (my-ess-THEE-nee-uh GRAV-iss) is an autoimmune disease that causes weakness in the voluntary muscles (the muscles we can control).

What Are the Signs & Symptoms of MG?

Myasthenia gravis happens when connections between nerves and muscles get blocked. With MG, a person develops antibodies that attack a muscle's nerve receptors. These receptors are what give muscles the signal to work. When messages from the nerve to the muscles get blocked by antibodies, weakness results.

Symptoms of MG can include ptosis or double vision; clumsiness and frequent falls; trouble speaking, chewing, or swallowing; changes in facial expressions; and a weak neck, making it hard to hold up the head.

How Is Myasthenia Gravis Treated?

Treatment options include:

• medicines that suppress the immune system and can be taken by mouth (such as prednisone)
• intravenous immunoglobulins (IVIG), which blocks the action of the antibodies causing the condition
• plasmapheresis, which removes some antibodies from the blood
• surgery to remove the thymus (thymectomy). Removing it can make the immune system less active.
• medicines that improve the signaling between the nerves and the muscles, which can help to improve muscle strength

What Else Should I Know?

For many MG patients, symptoms usually can be controlled. In some cases, long-term remission is possible.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.