Muscular dystrophy (MD) is a group of inherited diseases in which the muscles that control movement (called voluntary muscles) progressively weaken. In some forms of this disease, the heart and other organs are also affected.
Muscular dystrophy can appear in infancy up to middle age or later, and its form and severity are determined in part by the age at which it occurs. Some types of muscular dystrophy typicallyaffect only males; some people with MD enjoy a normal life span with mild symptoms that progress very slowly; others experience swift and severe muscle weakness and wasting, dying in their late teens to early 20s.
The various types of MD affect more than 50,000 Americans. Through advances in medical care, children with muscular dystrophy are living longer than ever before.
Muscular Dystrophy Symptoms by Type
Myotonic (also called MMD or Steinert's disease). The most common form of muscular dystrophy in adults, myotonic muscular dystrophy affects both men and women, and it usually appears any time from early childhood to adulthood. In rare cases, it appears in newborns (congenital MMD). The name refers to a symptom, myotonia -- prolonged spasm or stiffening of muscles after use. This symptom is usually worse in cold temperatures. The disease causes muscle weakness and also affects the central nervous system, heart, gastrointestinal tract, eyes, and hormone-producing glands. In most cases, daily living isn't restricted for many years. Those with myotonic MD have a decreased life expectancy.
Duchenne. The most common form of muscular dystrophy in children, Duchenne muscular dystrophy typically affects only males. It appears between the ages of 2 and 6. The muscles decrease in size and grow weaker over time yet may appear larger. Disease progression varies, but many people with Duchenne (1 in 3,500 boys) need a wheelchair by the age of 12. In most cases, the arms, legs, and spine become progressively deformed, and there may be some cognitive impairment. Severe breathing and heart problems mark the later stages of the disease. Those with Duchenne MD usually die in their late teens or early 20s.
Becker. This form is similar to Duchenne muscular dystrophy, but the disease is much milder: symptoms appear later and progress more slowly. It usually appears between the ages of 2 and 16 but can appear as late as age 25. Like Duchenne muscular dystrophy, Becker muscular dystrophy typically affects only males (1 in 30,000) and causes heart problems. Disease severity varies. Those with Becker can usually walk into their 30s and live further into adulthood.
Limb-girdle. This appears in the teens to early adulthood and affects males and females. In its most common form, Limb-girdle muscular dystrophy causes progressive weakness that begins in the hips and moves to the shoulders, arms, and legs and the heart may be affected. Within 20 years, walking becomes difficult or impossible. Sufferers typically live to middle age to late adulthood.
Facioscapulohumeral. Facioscapulohumeral refers to the muscles that move the face, shoulder blade, and upper arm bone. This form of muscular dystrophy appears in the teens to early adulthood and affects males and females. It progresses slowly, with short periods of rapid muscle deterioration and weakness. Severity ranges from very mild to completely disabling. Walking, chewing, swallowing, and speaking problems can occur. About 50% of those with facioscapulohumeral MD can walk throughout their lives, and most live a normal life span. It may also bee associated with seizures, mental health problems, and can involve the heart
Congenital. Congenital means present at birth. Congenital muscular dystrophies progress slowly and affect males and females. The two forms that have been identified -- Fukuyama and congenital muscular dystrophy with myosin deficiency -- cause muscle weakness at birth or in the first few months of life, along with severe and early contractures (shortening or shrinking of muscles that causes joint problems). Fukuyama congenital muscular dystrophy causes abnormalities in the brain and often seizures.
Oculopharyngeal. Oculopharyngeal means eye and throat. This form of muscular dystrophy appears in men and women in their 40s, 50s, and 60s. It progresses slowly, causing weakness in the eye and face muscles, which may lead to difficulty swallowing. Weakness in pelvic and shoulder muscles may occur later. Choking and recurrent pneumonia may occur.
Distal. This group of rare diseases affects adult men and women. It causes weakness and wasting of the distal muscles (those farthest from the center) of the forearms, hands, lower legs, and feet. It is generally less severe, progresses more slowly, and affects fewer muscles than other forms of muscular dystrophy.
Emery-Dreifuss. This rare form of muscular dystrophy appears from childhood to the early teens and affects mainly males. In very rare cases, females can be affected. For that to happen, both of a girls X chromosomes (the one they get from their mother and the one from their father) would have to have the defective gene. It causes muscle weakness and wasting in the shoulders, upper arms, and lower legs. Life-threatening heart problems are common and can also affect carriers -- those who have the genetic information for the disease but do not develop the full-blown version (including mothers and sisters of those with Emery-Dreifuss MD). Muscle shortening (contractures) occurs early in the disease. Weakness can spread to chest and pelvic muscles. The disease progresses slowly and causes less severe muscle weakness than some other forms of muscular dystrophy.
Muscular Dystrophy Treatment
There is no cure for muscular dystrophy, but treatments can help manage symptoms and improve quality of life.
Medications
Prescription drugs are available to control muscular dystrophy symptoms or slow their progression. Medications for muscular dystrophy include:
Steroids. Corticosteroids, such as prednisone and deflazacort (Emflaza), are the standard of care for muscular dystrophy. They help improve muscle strength and breathing and decrease weakness. Side effects include high blood pressure and weight gain. People who use steroids for a long time are at risk for brittle bones.
Medicines targeting gene mutations. Eteplirsen (Exondys 51) and golodirsen (Vyondys 53) increase the level of the gene dystrophin. They’re approved to specifically treat Duchenne muscular dystrophy.
Anticonvulsants. Often used to treat epilepsy, these antiseizure drugs may also help reduce muscle spasms.
Immunosuppressants. These powerful medicines are often used to treat lupus and other autoimmune diseases. When given to people with muscular dystrophy, they may help prevent some muscle cell damage.
Antibiotics. The doctor may prescribe an antibiotic to treat a lung infection, which is common in people with muscular dystrophy.
Muscular Dystrophy Diagnosis
To start, your doctor will examine your child and ask questions about medical and family health history. Muscular dystrophy is diagnosed using several different tests. These may include:
Muscle biopsy. A small piece of muscle tissue is removed and examined to confirm the diagnosis or rule out another muscle disease.
Genetic (DNA) testing. Genes passed down through families can cause some forms of muscular dystrophy. A blood test can determine if you or your child has the gene.
Neurological tests. Various tests are done to check nervous system function, reflexes, and coordination. One example is a nerve conduction study, also called a nerve function test, or electromyography (EMG).
Your Family, Our Responsibility !