Muscular Dystrophy
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Muscular Dystrophy

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Definition

Muscular dystrophy is a group of inherited, progressive muscle disorders. All forms of muscular dystrophy cause progressive weakness and degeneration of the muscles that control movement. Some also affect the heart muscle or other organs. Age of onset is between infancy to adulthood. The most common form is called Duchenne dystrophy. Other forms include Becker (a milder form than Duchenne) and myotonic muscular dystrophy, which can have its onset in late adulthood.

Causes

Muscular dystrophy is an genetic condition that 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

A risk factor is something that increases your chance of getting a disease or condition.

Risk factors include:

  • Family member with muscular dystrophy
  • Sex: male gender 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, and 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)

Severe Muscle Contraction of the Hand

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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 can 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, and perform 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
  • Electromyogram (EMG)—measures electrical impulses coming from muscles
  • Nerve conduction study (NCS)—measures electrical impulses in the nerves

Treatment

There is no cure for muscular dystrophy; 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 on your limbs may improve your ability to move around without using a wheelchair. A back brace may retard curvature of the spine.

Medication

Medications may include:

  • Corticosteroids to relieve muscle weakness
  • Creatine supplementation (shown to reduce fatigue and increase strength in some studies)
  • Drugs for heart problems if muscular dystrophy affects the heart

Surgery

In severe cases, surgery may be required to release muscles that are painfully tight. If heart problems are involved, a pacemaker may be surgically implanted.

Prevention

Muscular dystrophy is an inherited disease. Seek 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:

Creatine. EBSCO Publishing Health Library, Natural and Alternative Treatments website. Available at: http://healthlibrary.epnet.com/GetContent.aspx?token=da29d243-e573-4601-8b42-77cd0ccb14b2chunkiid=120459 . Accessed March 5, 2008.

Duchenne muscular dystrophy. EBSCO Publishing Dynamed website. Available at: http://www.ebscohost.com/dynamed . 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.

The Merck Manual of Medical Information . 17th ed. Simon and Schuster, Inc; 2000.

Moxley RT, Heatwole C. Myotonic Dystrophy. In: Gilman S, editor. MedLink Neurology . San Diego, CA: MedLink Corporation. Available at: http://www.medlink.com . Accessed March 16, 2007.

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

National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/ .



Last reviewed February 2008 by J. Thomas Megerian, MD, PhD, FAAP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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