Myasthenia Gravis

What is myasthenia gravis?

Myasthenia gravis is an autoimmune disease. It causes extreme weakness of muscles. Your body's immune system, which normally fights infection, attacks receptors on the muscles that pick up nerve impulses. This blocks the action of chemicals that transmit signals from the nerves to the muscles.

How does it occur?

The cause of myasthenia gravis is still unknown. It sometimes occurs with other immune system disorders. The illness may begin at any age, but most commonly starts between the ages of 20 and 40. In this age range, it is more common in women than men. When it begins after age 40, the disease affects men and women equally. Rarely, it is caused by tumors of the thymus gland.

What are the symptoms?

Symptoms may include:

muscle weakness that gets worse with activity and improves with rest
fatigue
eye problems such as double vision or droopy eyelids caused by weak eye muscles
weakness in the muscles of the face, throat, and neck that may cause difficulty speaking, chewing, and swallowing
trouble performing activities that use the muscles of the arms or legs, such as climbing stairs or combing hair
trouble breathing because of weakness in the respiratory muscles, which may be life-threatening.

Weakness, which gets worse over time, can vary from person to person and from day to day in the same person. Stress, infection, or other factors make symptoms worse. You may have symptom-free periods (remissions) followed by recurrences (relapses).

How is it diagnosed?

Your health care provider will examine you and take your medical history. You may have tests such as:

Tensilon test. This test involves giving you a drug that temporarily restores power to the muscles by supplying the chemicals blocked by the disease. A good response to this drug helps confirm the diagnosis.
Electromyography (EMG). This tests the function of nerves and muscles.
Blood tests. These can check if certain antibodies are present in your blood.

What is the treatment?

Treatment may include:

drug therapy with medicines that temporarily improve muscle strength by increasing the ability of the muscle to receive impulses from the nerves
taking steroids or other drugs that suppress your body's immune response
exchanging your plasma, the fluid part of your blood that contains antibodies (the proteins that are mistakenly attacking your body), with antibody-free plasma
removal of the thymus gland, or removal of a tumor on the thymus gland, which may improve your condition.

How long will effects last?

With treatment, you can expect to lead a nearly normal life. Sometimes muscle weakness may disappear temporarily. There is no cure, except in rare instances where the disease is caused by a tumor of the thymus gland (a tissue of the immune system) that is surgically removed.

How can I take care of myself?

If you are on drug therapy, it is very important to take your medicine on an exact schedule. Any delay in taking medicine may leave you unable to swallow or breathe. In this situation, get emergency treatment right away. You may want to set an alarm clock to remind you to take your medicine. These medicines should generally be taken with milk and crackers or other nonacid food.

Sedatives and narcotic analgesics (pain medicines) can cause a person with myasthenia gravis to have severe breathing problems. Wear a medical alert bracelet stating that you have myasthenia gravis.

Since physical exertion may make your symptoms worse, you may have to modify your activity somewhat.

You may also want to:

Join a support group and ask your family to help you reduce stress.
Wear an eye patch to relieve double vision.

More information is available from:

Myasthenia Gravis Foundation of America
123 Madison Street, Suite 800
Chicago, IL 60602
(800) 541-5454
(312) 853-0522
Web site: http://www.myasthenia.org

National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
800-352-9424
(301) 496-5751
Web site: http://www.ninds.nih.gov.

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIA File BRN3419F.HTM Release 9.0/2006