Muscular Dystrophy (Duchenne, Facioscapulohumeral, and Myotonic Dystrophies)

Muscular dystrophy is the general term for hereditary muscle diseases characterized by progressive weakness and disability. There are numerous forms, but the most common are: Duchenne dystrophy, the most severe type. It strikes boys who inherit the gene from their mothers. The progressive muscle weakness, usually apparent by age three, is caused by a lack of the protein dystrophin in muscle cells. The disability affects mainly the torso and limb muscles, and by age 12, most patients are confined to a wheelchair. Progressive weakening of the chest muscles usually results in respiratory failure or fatal pneumonia by age 20.

Facioscapulohumeral (FSH) dystrophy, which occurs in both sexes, with onset during adolescence. Typically, there is difficulty in raising the arms overhead, changing facial expression, and perhaps closing the eyes due to muscle weakness. The back and shoulders become progressively curved. The person can still walk and life expectancy is close to normal.

Myotonic dystrophy, which affects various organs as well as muscles. The symptoms vary from person to person. In most patients, muscles fail to relax after use -- a condition called myotonia. In some cases, there is obvious wasting of facial and neck muscles, which may impair swallowing and blinking. Complications can range from increased miscarriages in women and sterility in men to cataracts and personality changes. However, many people with myotonic dystrophy live normal lives, often unaware of the disease.

Diagnostic Studies and Procedures

A family history of muscular dystrophy plus a gradual weakening and shrinking, or atrophy, of muscles points to the possibility of dystrophy. A diagnostic workup will include blood, urine, and spinal fluid studies, and electromyography to assess muscle responses. Muscle biopsy helps to identify the type of dystrophy. In Duchenne dystrophy, a biopsy will show the presence of excessive fat and connective tissue, which weaken muscle fibers. In FSH dystrophy, it will reveal abnormal muscle fibers and cell structure. Because myotonic dystrophy can affect organs as well as muscles, it is often misdiagnosed. However, electromyography will show abnormal muscle function, and an electrocardiogram may reveal abnormal heart function.

Medical Treatments

As yet, there is no cure, so treatment is concentrated on easing symptoms and preventing complications. If the chest muscles are weakened, antibiotics may be prescribed to prevent pneumonia and other respiratory infections. Digitalis and other heart medications are used to strengthen the heartbeat and to steady cardiac arrhythmias. Quinine, used to treat malaria, is sometimes given to prevent the muscle contractions of myotonic dystrophy. Androgens, male sex hormones that promote muscle-building, may be used to relieve some of its symptoms, but do not seem to help other types of dystrophy.

Surgery may be recommended to forestall certain disabilities or alleviate symptoms. For example, a procedure to lengthen leg tendons and cut the fascia, fibrous tissue that encases the muscles, sometimes prolongs mobility. An experimental treatment for Duchenne dystrophy entails injecting millions of healthy muscle cells into the patient's diseased muscles. Some patients appear to improve, but long-term benefits are doubtful. Researchers hold the most hope for advances in genetic engineering that will enable doctors to replace the defective gene.

Alternative Therapies

A controversial alternative therapy, developed by the parents of a boy who suffered from muscle disease, is said to delay the progression of some types of dystrophy. However, its benefits have not been proven. A commercial version (known as Lorenzo's oil), made from purified olive and rape seed oils, is under development.

Nutrition Therapy. A high-protein, low-fat diet is advocated, and vitamin E supplements may be recommended. Its important to maintain normal weight, extra pounds can strain weak muscles further and exacerbate spinal deformity.

Physical Therapy. All patients can benefit from intensive physical therapy. Special leg braces and crutches help to retain mobility, and passive and active stretching exercises help to prevent muscle shortening and contractures. These exercises may be combined with therapeutic massage and music therapy.

Self-Treatment

The goal is to stay active and keep a positive attitude. Prolonged bed rest should be avoided, as it hastens muscle wasting. Regular exercise, though difficult, is essential to forestall disability.

Other Causes of Muscle Weakness

Multiple sclerosis, myasthenia gravis, amyotrophic lateral sclerosis (Lou Gehrig's disease), and polio are among the disorders causing muscle weakness.