Health Issues: Muscular Dystrophy
Diagnosis
A careful review of your family's history of muscle disease can help your doctor reach a diagnosis. In addition to a medical history review and physical examination, your doctor may rely on the following in diagnosing muscular dystrophy:
- Blood tests. Damaged muscles release enzymes, such as creatine kinase (CK), into your blood. High blood levels of CK suggest a muscle disease, such as muscular dystrophy.
- Electromyography. A thin-needle electrode is inserted through your skin into the muscle to be tested. Electrical activity is measured as you relax and as you gently tighten the muscle. Changes in the pattern of electrical activity can confirm a muscle disease. The distribution of the disease can be determined by testing different muscles.
- Ultrasonography. High-frequency sound waves are used to produce precise images of tissues and structures within your body. An ultrasound is a noninvasive way of detecting certain muscle abnormalities, even in the early stages of the disease.
- Muscle biopsy. A small piece of muscle is taken for laboratory analysis. The analysis distinguishes muscular dystrophies from other muscle diseases. Special tests can identify dystrophin and other markers associated with specific forms of muscular dystrophy.
- Genetic testing. Blood samples are examined for mutations in some of the genes that cause different types of muscular dystrophy. For Duchenne's and Becker's muscular dystrophies, standard tests examine just the portions of the dystrophin gene responsible for most cases of these types of MD. These tests identify deletions or duplications on the dystrophin gene in more than two-thirds of people with Duchenne's and Becker's MDs. The genetic defects responsible for Duchenne's and Becker's muscular dystrophies are harder to identify in other cases of those affected, but new tests that examine the entire dystrophin gene are making it possible to pinpoint tiny, less common mutations.
