Monday, June 25, 2012

What Is Muscular Dystrophy? What Causes Muscular Dystrophy?

The muscular dystrophies (MD) are a group a group of genetic diseases characterized by progressive weakness and degeneration of the skeletal or voluntary muscles which control movement. The muscles of the heart and some other involuntary muscles are also affected in some forms of muscular dystrophy, and a few forms involve other organs as well.

According to Medilexicon's medical dictionary:

Muscular Dystrophy a general term for a number of hereditary, progressive degenerative disorders affecting skeletal muscles, and often other organ systems.


Some forms of MD are seen in infancy or childhood, while others may not appear until middle age or later. The disorders differ in terms of the distribution and extent of muscle weakness, age of onset, rate of progression, and pattern of inheritance.

Duchenne MD is the most common form of MD and primarily affects boys. It is caused by the absence of dystrophin, a protein involved in maintaining the integrity of muscle. Onset is between 3 and 5 years and the disorder progresses rapidly. Most boys are unable to walk by age 12, and later need a respirator to breathe.

About 1 out of every 3,500 to 5000 boys is born with MD, and there are about 400 to 600 new cases each year in the United States. Girls in these families have a 50 percent chance of inheriting and passing the defective gene to their children.

Boys with Becker MD (very similar to but less severe than Duchenne MD) have faulty or not enough dystrophin.

Facioscapulohumeral MD usually begins in the teenage years. It causes progressive weakness in muscles of the face, arms, legs, and around the shoulders and chest. It progresses slowly and can vary in symptoms from mild to disabling.

Myotonic MD is the disorder's most common adult form and is typified by prolonged muscle spasms, cataracts, cardiac abnormalities, and endocrine disturbances. Individuals with myotonic MD have long, thin faces, drooping eyelids, and a swan-like neck.

What are the symptoms of Muscular Dystrophy?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.

The symptoms of muscular dystrophy are the result of a deterioration of the body's muscles. This deterioration is due to the death of the muscle cells and muscle tissues and leads to ongoing muscle wasting and muscle weakness. Muscular dystrophy progresses and gets worse over time eventually. This results in difficulty walking, disability, the need for leg and hand braces, and ultimately the use of a wheelchair.

The muscle weakness of muscular dystrophy often begins in the legs. This makes it difficult for a child to walk normally, and he or she may walk with their feet wide apart to help keep balance. The child may use his or her hands and arms to get up from the floor and assist with standing. There may be frequent falls, a waddling gait, limited range of motion and pain in the calves. By 12 years of age, a child is often completely unable to walk and must use a wheelchair.

Over time, muscle weakness gets worse in severity and also progresses to include muscles in other parts of the body. These include muscles in the neck and arms. The muscle in the chest may also be affected. This can result in such complications as deformities in development of the bones of the chest and spine and scoliosis. This can lead to serious complications, including difficulty breathing and pneumonia. Some children may also have mental impairment, cardiac arrhythmias or cardiomyopathy.

The progression and severity of the symptoms of muscular dystrophy varies greatly between individuals and the type of muscular dystrophy. Some people may not develop symptoms until adulthood, and while many people experience severe disabilities and eventually die from the disease, others may have mild symptoms, no significant disability, and a normal life expectancy.

What are the causes of Muscular Dystrophy?

Researchers are quickly learning more about what causes the genetic disorder that leads to muscular dystrophy, and about possible treatments for the disease.

There are many types of muscular dystrophy that are caused by mutations in several different genes. For example, Duchenne muscular dystrophy and Becker muscular dystrophy are caused by mutations in the dystrophin gene, whereas limb-girdle muscular dystrophies are caused by mutations in other genes.

Diagnosing Muscular Dystrophy

If a pediatrician suspects that a child may have muscular dystrophy, they will likely begin by testing the creatine kinase (CK) level in the blood. This muscle enzyme is very high in children with muscular dystrophy.

After finding a high CK level, the pediatrician will likely do DNA testing to look for mutations in the gene that makes dystrophin, an important muscle protein. If this genetic testing is negative, then a muscle biopsy may be done to confirm the diagnosis of muscular dystrophy.

Although it is possible to screen newborns for muscular dystrophy by testing their level of creatine kinase, it is not routinely done. One of the big problems is that only about 10 percent of newborns with a high CK level will actually have muscular dystrophy. The other 90 percent will have CK levels that return to normal when they are a few weeks old.

Often, there is a loss of muscle mass, which may be hard to see because some types of muscular dystrophy cause a buildup of fat and connective tissue that makes the muscle appear larger. This is called pseudohypertrophy.

What are the treatment options for Muscular Dystrophy?

Physical therapy can help a child maintain muscle tone and reduce the severity of joint contractures with exercises that keep the muscles strong and the joints flexible.

A physical therapist also uses bracing to help prevent joint contractures, a stiffening of the muscles near the joints that can make it harder to move and can lock the joints in painful positions. By providing extra support in just the right places, bracing can extend the time that a child with MD can walk independently.

If a person has Duchenne muscular dystrophy, a doctor may prescribe the steroid prednisone to help slow the rate of muscle deterioration. By doing so, the child may be able to walk longer and live a more active life.

There is some debate over the best time to begin prednisone treatment, but most doctors prescribe it when a child is 5 or 6 years old or when the child's strength begins to significantly decline.

Prednisone does have side effects, though. It can cause weight gain, which can put even greater strain on already weak muscles. It also can cause a loss of bone density and, possibly, lead to fractures. If prescribing prednisone, a doctor will have to closely monitor results.

Some persons with severe cases undergo spinal fusion, a surgery that can reduce pain, lessen the severity of the curvature so that a child can sit upright and comfortably in a chair, and ensure that the spine curvature doesn't have an effect on breathing. Usually, spinal fusion surgery only requires a short hospital stay.

Many people with MD also have weakened heart and respiratory muscles. As a result, they can't cough out phlegm and sometimes develop respiratory infections that can quickly become serious. Good general health care and regular vaccinations are especially important for children with muscular dystrophy to help prevent these infections.

Preventing Muscular Dystrophy

As there this is an inherited condition, there is no method of prevention. However, research and awareness is ongoing.

Within the United States, the three primary federally funded organizations that focus on muscular dystrophy include the National Institute of Neurological Disorders and Stroke (NINDS), National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), and National Institute of Child Health and Human Development (NICHD).

In 1966, the Muscular Dystrophy Association began its annual Jerry Lewis MDA Telethon, which has arguably done more to raise awareness of muscular dystrophy than any other event or initiative.

On December 18, 2001 the MD CARE Act was signed into law and amends the Public Health Service Act to provide research for the various muscular dystrophies. This law also established the Muscular Dystrophy Coordinating Committee to help focus research efforts through a coherent research strategy.

No comments:

Related Posts Plugin for WordPress, Blogger...

Popular Posts