Muscular Dystrophy

Muscular dystrophy (MD) is a group of disorders that affects voluntary muscles, mainly those around the hips and shoulders. MD can affect people at any age. The most common type seen in children is Duchenne muscular dystrophy, which affects an estimated 1 in 3,500 boys worldwide. UCSF's Neuromuscular Clinic has been recognized as a Certified Duchenne Care Center — signifying a center that provides high-quality, comprehensive care for Duchenne MD — by Parent Project Muscular Dystrophy.

Over time, children with MD lose muscle bulk and strength. Eventually, children may need a power wheelchair or scooter, especially for long distances. The heart and breathing can also become affected as the condition progresses.

MD is caused by a problem with genes that are involved in making proteins needed for proper muscle function. When protein problems arise because one of these genes is faulty, the muscle fibers don't work correctly. Gradually, the muscles become weak enough that people experience symptoms. The protein that is affected determines how fast the disease progresses, and if problems will arise in the heart or with breathing.

The main symptom of all MD disorders is progressive weakening of the muscles. Otherwise, the symptoms and the age they appear can vary depending on the type of MD. Common early symptoms include:

  • Difficulty walking, frequent falls or toe walking
  • Difficulty rising from a seated position or from the floor without using the arms (called a Gower's maneuver)

In diagnosing any form of muscular dystrophy, doctors usually begin by taking a patient and family history and performing a physical examination. Occasionally, patients will undergo electromyography, a test that looks at the electrical activity of the muscles and nerves, to see where the problem lies.

Levels of creatine kinase (CK), an enzyme that leaks out of damaged muscle, are often evaluated with a blood test. When elevated CK levels are found, it usually means muscle is being destroyed by some abnormal process, such as a muscular dystrophy or inflammation. Therefore, a high CK level suggests that the muscles themselves are the likely cause of the weakness, but it doesn't determine what the muscle disorder might be.

Today, DNA testing for genetic flaws that are known to cause MD is available for many forms of the disease. If a particular type of MD is suspected, DNA testing, using a blood sample, may be performed relatively early in the diagnostic process. In some cases, the doctor must order a muscle biopsy, the surgical removal of a small sample of muscle from the patient.

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Medications

Currently, Duchenne MD is the only form of MD with research evidence showing that medication can be beneficial. Steroids — also called glucocorticoids or corticosteroids — are the only drugs known to slow the decline in muscle strength and motor function in DMD. The goal of steroid use is to help the child walk independently for longer, to allow more participation in everyday activities, and to later minimize breathing, heart and orthopedic problems. They can also reduce the risk of scoliosis, an abnormal curvature of the spine.

Steroids do have side effects, including weight gain, behavioral issues, bleeding in the gastrointestinal tract, high blood pressure and the development of diabetes. Children need to be followed closely when on this medication and cannot stop taking it suddenly.

Albuterol has also been tested in DMD as well as other neuromuscular disorders, and evidence suggests some mild benefit in increasing lean muscle mass. Some patients also feel an increase in energy. Albuterol has few side effects, most commonly anxiety, agitation and tremor.

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UCSF Research & Clinical Trials

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Reviewed by health care specialists at UCSF Benioff Children's Hospital.

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San Francisco, CA 94158
Phone: (415) 353-7596
Fax: (415) 353-2400
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