Muscular dystrophy (MD) is a group of inherited muscle diseases in which muscle fibers are unusually susceptible to damage. Muscles, primarily voluntary muscles, become progressively weaker. In the late stages of muscular dystrophy, fat and connective tissue often replace muscle fibers. Some types of muscular dystrophy affect heart muscles, other involuntary muscles and other organs.
The most common types of muscular dystrophy appear to be due to a genetic deficiency of the muscle protein dystrophin.
There's no cure for muscular dystrophy, but medications and therapy can slow the course of the disease.
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.
- 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
- Eyelid drooping (ptosis)
- Frequent falls
- Problems walking (delayed walking)
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.
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 long as possible.
The person should be as active as possible. Complete inactivity (such as bed rest) can make the disease worse.
There's currently no cure for any form of muscular dystrophy. Research into gene therapy may eventually provide treatment to stop the progression of some types of muscular dystrophy. Current treatment is designed to help prevent or reduce deformities in the joints and the spine and to allow people with MD to remain mobile as long as possible. Treatments may include various types of physical therapy, medications, assistive devices and surgery.
As muscular dystrophy progresses and muscles weaken, fixations (contractures) can develop in joints. Tendons can shorten, restricting the flexibility and mobility of joints. Contractures are uncomfortable and may affect the joints of your hands, feet, elbows, knees and hips.
One goal of physical therapy is to provide regular range-of-motion exercises to keep your joints as flexible as possible, delaying the progression of contractures, and reducing or delaying curvature of your spine. Using hot baths (hydrotherapy) also can help maintain range of motion in joints.
In some cases, doctors may prescribe medications to slow the progression and manage signs and symptoms of muscular dystrophy:
- Muscle spasms, stiffness and weakness (myotonia). Medications that may be used to help manage myotonia associated with MD include mexiletine (Mexitil), phenytoin (Dilantin, Phenytek), baclofen (Lioresal), dantrolene (Dantrium) and carbamazepine (Tegretol, Carbatrol).
- Muscle deterioration. The anti-inflammatory corticosteroid medication prednisone may help improve muscle strength and delay the progression of Duchenne's MD. The immunosuppressive drugs cyclosporin and azathioprine also are sometimes prescribed to delay some damage to dying muscle cells.
Medications that may be used to help manage myotonia associated with MD include mexiletine (Mexitil), phenytoin (Dilantin, Phenytek), baclofen (Lioresal), dantrolene (Dantrium) and carbamazepine (Tegretol, Carbatrol).
Braces can both provide support for weakened muscles of your hands and lower legs and help keep muscles and tendons stretched and flexible, slowing the progression of contractures. Other devices, such as canes, walkers and wheelchairs, can help maintain mobility and independence. If respiratory muscles become weakened, using a ventilator may become necessary.
To release the contractures that may develop and that can position joints in painful ways, doctors can perform a tendon release surgery. This may be done to relieve tendons of your hip and knee and on the Achilles tendon at the back of your foot. Surgery may also be needed to correct curvature of the spine.
Because respiratory infections may become a problem in later stages of muscular dystrophy, it's important to be vaccinated for pneumonia and to keep up to date with influenza shots.
For family members of people with muscular dystrophy, coping with the illness involves a major commitment of physical, emotional and financial effort. The disease presents challenges in the classroom, in the home and in all aspects of life.
In dealing with a disease such as muscular dystrophy, support groups can be a valuable part of a wider network of social support that includes health care professionals, family, friends and a place of religious worship.
Support groups bring together people, family and friends who are coping with the same kind of physical or mental health challenge. Support groups provide a setting in which people can share their common problems and provide ongoing support to one another.
Ask your doctor about self-help groups that may exist in your community. Your local health department, public library, telephone book and the Internet also may be good sources to locate a support group in your area.