Myasthenia Gravis (MG)

What is MG?

MG stands for myasthenia (my-es-THEE-nee-uh) gravis (graw-vis). It is a disease that causes painless muscle weakness. It can affect the muscles of the eyes, face, neck, arms, and legs. When MG weakens the eye muscles, for example, a person may get double vision or drooping eyelids. MG often affects the muscles used to chew, swallow, and breathe. Rest improves muscle weakness, but MG is chronic, which means lifelong. Treatment for MG, however, allows most patients to lead normal or nearly normal lives.

What causes MG?

MG is a disease of the immune system. The immune system fights infections, which come from outside the body. A healthy immune system produces antibodies that attack these infections. When you have MG, the antibodies also attack your body. This makes a certain chemical in your body less active. The chemical is acetylcholine (uh-see-tol-KO-leen). As this chemical becomes less active, messages don’t travel properly from your nerves to your muscles. Your muscles then do not contract normally. As a result, you become weak and very tired. Sometimes but not often, a person with MG also has a tumor of the thymus (THIGH-mis) gland.

What are the symptoms of MG?

MG symptoms vary widely from person to person. Symptoms may include:

  • Drooping eyelids
  • Double vision
  • Trouble swallowing
  • Weak arms and legs
  • Slurred speech
  • Fading voice tone

Heat and cold can make symptoms worse. So can illness, stress, or a woman’s monthly period. In time, trouble swallowing or coughing can make it hard to eat and drink normally.

How is MG detected?

Several types of testing help to identify MG:

  • Blood tests — Samples of blood are tested for MG antibodies.
  • Tensilon test — A chemical (brand name Tensilon) is injected to see how muscles respond.
  • EMG, or electromyography (ee-lek-tro-my-OG-ruff-ee) — The electric

Several treatments are available to relieve symptoms and slow down MG:

  • Immunoglobulin (IM-you-no-GLOB-you-lin) — Called IG for short, this substance helps to calm down the immune system. It is given by IV (intravenously).
  • Plasmapheresis (plaz-muh-fer-EE-sis) — This procedure removes MG antibodies from the blood. The blood passes from the patient’s body through an IV line, is purified, and then passes back into the body.
  • Medicine — The drug pyridostigmine (peer-ih-DOS-tig-meen) makes more acetylcholine available in the body. Steroids and other drugs make the immune system less active.
  • Surgery — The thymus gland can be removed when it is linked to MG. The operation is called a thymectomy (thigh-MEK-tuh-mee).

Can rehab help?

Your doctor may suggest rehab. Rehab can help you to adapt so you can perform the tasks of everyday life. You may have physical therapy (PT), occupational therapy (OT), or both.

For more information

Some helpful resources include:

Myasthenia Gravis Foundation of America
355 Lexington Avenue, Floor 15
New York, New York, 10017
Phone: 212-297-2156 or 800-541-5454
Fax: 212-370-9047
E-mail: mgfa@myasthenia.org
Web: http://www.myasthenia.org


National Institute of Neurological Disorders and Stroke
P.O. Box 5801Bethesda, MD 20824
Phone: 301-496-5751or 1-800-352-9424
TTY: 301-468-5981
Web: http://www.ninds.nih.gov

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