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Muscular Dystrophy

(MD)

Definition

Muscular dystrophy is a group of inherited, progressive muscle disorders. All forms cause progressive weakness and degeneration of the muscles that control movement. Some also affect the heart or other organs. Age of onset is between infancy to adulthood. The different forms include:

Duchenne dystrophy (the most common)
Becker (a milder form than Duchenne)
Myotonic muscular dystrophy (can have its onset in late adulthood)

Causes

This condition is caused by defects in genes that control muscle development and function. In some cases, the genes are passed from parent to child. In other cases, the genetic mutation occurs spontaneously.

Risk Factors

These factors increase your chance of developing muscular dystrophy. Tell your doctor if you have any of these risk factors:

Family member with muscular dystrophy
Sex: male for some types (Duchenne and Becker)

Symptoms

Symptoms common to most forms of muscular dystrophy may include:

Initial symptoms:

Progressive weakening of muscles—Usually, those muscles closest to the trunk become weak first. Then, muscles further away weaken as the disease advances.
Enlargement of muscles as they weaken
Clumsiness
Frequent falling and difficulty getting up

Later symptoms:

Severe muscle deterioration, usually leading to use of a wheelchair
Distortion of the body
Muscle contraction and stiffening (often severe)
Difficulty breathing

Severe Muscle Contraction of the Hand

Symptoms specific to Duchenne and Becker dystrophy include:

Abnormally curved spine
Enlargement and weakening of the heart muscle
Pneumonia and other respiratory infections

Symptoms specific to myotonic muscular dystrophy include:

Difficulty in letting go after a handshake
Muscle weakness that affects the central nervous system, heart, digestive tract, glands, or eyes

Symptoms usually become progressively worse. In many forms, life expectancy is shortened.

Diagnosis

The doctor will ask about your symptoms and medical history. She will also do a physical exam.

Tests may include:

Muscle tissue biopsy —removal of a sample of muscle tissue for testing
Blood enzyme tests—testing a blood sample to look for elevated enzyme levels
Genetic testing-using blood samples
Electromyogram (EMG) —measures electrical impulses coming from muscles
Nerve conduction study (NCS) —measures electrical impulses in the nerves

Treatment

There is no cure. However, treatment may help improve the symptoms.

Treatment may consist of:

Physical Therapy and Exercise

Physical therapy and exercise can help prevent the muscles from permanently contracting and stiffening.

Braces

In earlier stages, wearing braces may improve your ability to move around. A back brace may slow curvature of the spine.

Medication

Medicines may include:

Corticosteroids to relieve muscle weakness (chronic steroids can also cause muscle injury called “steroid myopathy”)
Creatine supplements (shown to reduce fatigue and increase strength in some studies)
Drugs for heart problems if muscular dystrophy affects the heart

Much research is being done in this area. A new technique called “gene transfer” therapy has been used with some good early results in certain forms of dystrophy.

Surgery

In severe cases, surgery may be needed to release muscles that are painfully tight. If there are heart problems, a pacemaker may be needed.

Prevention

Muscular dystrophy is an inherited disease. Get genetic counseling if you are concerned about having a child with muscular dystrophy, especially if you:

Have muscular dystrophy or a family history of the disease
May be a carrier of the gene for muscular dystrophy
Have a partner with a family history of the disease

RESOURCES:

Muscular Dystrophy Association
http://www.mdausa.org/

Muscular Dystrophy Family Foundation
http://www.mdff.org/

Parent Project Muscular Dystrophy
http://www.parentprojectmd.org/

CANADIAN RESOURCES:

Canadian Institute of Health Research
http://www.cihr-irsc.gc.ca/

Muscle Dystrophy Canada
http://www.muscle.ca/

REFERENCES:

Berkow R. The Merck Manual of Medical Information . 17th ed. New York, NY: Pocket; 2000.

Creatine. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/thisTopic.php?marketID=15topicID=81 . Updated November 2008. Accessed March 5, 2008.

Duchenne muscular dystrophy. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated January 31, 2008. Accessed February 23, 2008.

Kasper DL, Braunwald E, Fauci AS, et al. Harrison's Principles of Internal Medicine . 16th ed. New York, NY: The McGraw-Hill Companies; 2005.

Moxley RT, Heatwole C. Myotonic dystrophy. Medlink website. http://www.medlink.com . Accessed March 16, 2007.

Muscular Dystrophy Association website. Available at: http://www.mdausa.org .

NINDS muscular dystrophy information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/ . Updated January 27, 2009. Accessed February 6, 2009.

Last reviewed January 2010 by Robert E. Leach, MD
Last Updated: 1/20/2010

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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