Health Encyclopedia

Muscular dystrophy

Definition

Muscular dystrophy is a group of disorders that involve muscle weakness and loss of muscle tissue that get worse over time.

Alternative Names

Inherited myopathy; MD

Causes, incidence, and risk factors

Many diseases called muscular dystrophies (MD) are inherited disorders, such as:

Becker's muscular dystrophy
Duchenne muscular dystrophy
Emery-Dreifuss muscular dystrophy
Facioscapulohumeral muscular dystrophy
Limb-girdle muscular dystrophy
Myotonia congenita
Myotonic dystrophy

Symptoms

Symptoms vary with the different types of muscular dystrophy.

All of the muscles may be affected. Or, only specific groups of muscles may be affected, such as those around the pelvis, shoulder, or face. Muscular dystrophy can affect adults, but the more severe forms tend to occur in early childhood.

Symptoms include:

Mental retardation (only present in some types of the condition)
Muscle weakness that slowly gets worse
- Delayed development of muscle motor skills
- Difficulty using one or more muscle groups
- Drooling
- Eyelid drooping (ptosis)
- Frequent falls
- Problems walking (delayed walking)

Signs and tests

A physical examination and your medical history will help the doctor determine the type of muscular dystrophy. Specific muscle groups are affected by different types of muscular dystrophy.

Signs may include:

Curved spine (scoliosis)
Joint contractures (clubfoot, clawhand, or others)
Low muscle tone (hypotonia)

Some types of muscular dystrophy involve the heart muscle, causing cardiomyopathy or disturbed heart rhythm (arrhythmias).

Often, there is a loss of muscle mass (wasting), which may be hard to see because some types of muscular dystrophy cause a build-up of fat and connective tissue that makes the muscle appear larger. This is called pseudohypertrophy.

A muscle biopsy may be used to confirm the diagnosis. In some cases, a DNA blood test may be all that is needed.

Other tests may include:

Electrocardiography (ECG)
Electromyography (EMG)
Serum CPK

This disease may also alter the results of the following tests:

Treatment

There are no known cures for the various muscular dystrophies. The goal of treatment is to control symptoms.

Physical therapy may help patients maintain muscle strength and function. Orthopedic appliances such as braces and wheelchairs can improve mobility and self-care abilities. In some cases, surgery on the spine or legs may help improve function.

Corticosteroids taken by mouth are sometimes prescribed to children to keep them walking for as along as possible.

The person should be as active as possible. Complete inactivity (such as bedrest) can make the disease worse.

Support Groups

You can ease the stress of illness by joining support groups where members share common experiences and problems. See muscular dystrophy - support group.

Expectations (prognosis)

The severity of disability depends on the type of muscular dystrophy. All types of muscular dystrophy slowly get worse, but how fast this happens varies widely.

Some types of muscular dystrophy, such as Duchenne muscular dystrophy, are deadly. Other types cause little disability and people with them have a normal lifespan.

Complications

Cardiomyopathy
Decreased ability to care for self
Decreased mobility
Joint contractures
Mental impairment (varies)
Respiratory failure
Scoliosis

Calling your health care provider

Call your health care provider if:

You have symptoms of muscular dystrophy.
You have a personal or family history of muscular dystrophy and you are planning to have children.

Prevention

Genetic counseling is advised when there is a family history of muscular dystrophy. Women may have no symptoms but still carry the gene for the disorder. Duchenne muscular dystrophy can be detected with about 95% accuracy by genetic studies performed during pregnancy.

References

Kliegman RM, Behrman RE, Jenson HB, Stanton BF. Muscular dystrophies. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 608.

Review Date:12/17/2008
Reviewed By:Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine; and Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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