Muscular dystrophy

Muscular dystrophy is a group of diseases that cause progressive weakness and loss of muscle mass. In muscular dystrophy, abnormal genes (mutations) interfere with the production of proteins needed to form healthy muscle.

There are many kinds of muscular dystrophy. Symptoms of the most common variety begin in childhood, mostly in boys. Other types don't surface until adulthood.

There's no cure for muscular dystrophy. But medications and therapy can help manage symptoms and slow the course of the disease.

The main sign of muscular dystrophy is progressive muscle weakness. Specific signs and symptoms begin at different ages and in different muscle groups, depending on the type of muscular dystrophy.

Duchenne type muscular dystrophy

This is the most common form. Although girls can be carriers and mildly affected, it's much more common in boys.

Signs and symptoms, which typically appear in early childhood, might include:

  • Frequent falls
  • Difficulty rising from a lying or sitting position
  • Trouble running and jumping
  • Waddling gait
  • Walking on the toes
  • Large calf muscles
  • Muscle pain and stiffness
  • Learning disabilities
  • Delayed growth

Becker muscular dystrophy

Signs and symptoms are similar to those of Duchenne muscular dystrophy, but tend to be milder and progress more slowly. Symptoms generally begin in the teens but might not occur until the mid-20s or later.

Other types of muscular dystrophy

Some types of muscular dystrophy are defined by a specific feature or by where in the body symptoms begin. Examples include:

  • Myotonic.
  • Facioscapulohumeral (FSHD).
  • Congenital.
  • Limb-girdle.

Seek medical advice if you notice signs of muscle weakness - such as increased clumsiness and falling - in you or your child.

Certain genes are involved in making proteins that protect muscle fibers. Muscular dystrophy occurs when one of these genes is defective. Each form of muscular dystrophy is caused by a genetic mutation particular to that type of the disease. Most of these mutations are inherited.

Muscular dystrophy occurs in both sexes and in all ages and races. However, the most common variety, Duchenne, usually occurs in young boys. People with a family history of muscular dystrophy are at higher risk of developing the disease or passing it on to their children.

The complications of progressive muscle weakness include:

  • Trouble walking. Some people with muscular dystrophy eventually need to use a wheelchair.
  • Trouble using arms. Daily activities can become more difficult if the muscles of the arms and shoulders are affected.
  • Shortening of muscles or tendons around joints (contractures). Contractures can further limit mobility.
  • Breathing problems. Progressive weakness can affect the muscles associated with breathing. People with muscular dystrophy might eventually need to use a breathing assistance device (ventilator), initially at night but possibly also during the day.
  • Curved spine (scoliosis). Weakened muscles might be unable to hold the spine straight.
  • Heart problems. Muscular dystrophy can reduce the efficiency of the heart muscle.
  • Swallowing problems. If the muscles involved with swallowing are affected, nutritional problems and aspiration pneumonia can develop. Feeding tubes might be an option.

Your doctor is likely to start with a medical history and physical examination.

After that, your doctor might recommend:

  • Enzyme tests.
  • Genetic testing.
  • Muscle biopsy.
  • Heart-monitoring tests (electrocardiography and echocardiogram).
  • Lung-monitoring tests.
  • Electromyography.

Although there's no cure for any form of muscular dystrophy, treatment for some forms of the disease can help extend the time a person with the disease can remain mobile and help with heart and lung muscle strength. Trials of new therapies are ongoing.

People with muscular dystrophy should be monitored throughout their lives. Their care team should include a neurologist with expertise in neuromuscular diseases, a physical medicine and rehabilitation specialist, and physical and occupational therapists.

Some people might also need a lung specialist (pulmonologist), a heart specialist (cardiologist, a sleep specialist, a specialist in the endocrine system (endocrinologist), an orthopedic surgeon and other specialists.

Treatment options include medications, physical and occupational therapy, and surgical and other procedures. Ongoing assessments of walking, swallowing, breathing and hand function enable the treatment team to adjust treatments as the disease progresses.

Your doctor might recommend:

  • Corticosteroids, such as prednisone and deflazacort (Emflaza), which can help muscle strength and delay the progression of certain types of muscular dystrophy. But prolonged use of these types of drugs can cause weight gain and weakened bones, increasing fracture risk.
  • Newer drugs include eteplirsen (Exondys 51), the first medication to be approved by the Food and Drug Administration (FDA) specifically to treat some people with Duchenne muscular dystrophy. It was conditionally approved in 2016. In 2019, the FDA approved golodirsen (Vyondys 53) for treatment of some people with Duchenne dystrophy who have a certain genetic mutation.
  • Heart medications, such as angiotensin-converting enzyme (ACE) inhibitors or beta blockers, if muscular dystrophy damages the heart.

Several types of therapy and assistive devices can improve the quality and sometimes the length of life in people who have muscular dystrophy. Examples include:

  • Range-of-motion and stretching exercises. Muscular dystrophy can restrict the flexibility and mobility of joints. Limbs often draw inward and become fixed in that position. Range-of-motion exercises can help to keep joints as flexible as possible.
  • Exercise. Low-impact aerobic exercise, such as walking and swimming, can help maintain strength, mobility and general health. Some types of strengthening exercises also might be helpful. But it's important to talk to your doctor first because some types of exercise might be harmful.
  • Braces. Braces can help keep muscles and tendons stretched and flexible, slowing the progression of contractures. Braces can also aid mobility and function by providing support for weakened muscles.
  • Mobility aids. Canes, walkers and wheelchairs can help maintain mobility and independence.
  • Breathing assistance. As respiratory muscles weaken, a sleep apnea device might help improve oxygen delivery during the night. Some people with severe muscular dystrophy need to use a machine that forces air in and out of their lungs (ventilator).

Surgery

Surgery might be needed to correct contractures or a spinal curvature that could eventually make breathing more difficult. Heart function may be improved with a pacemaker or other cardiac device.

Preventing respiratory infections

Respiratory infections can become a problem in muscular dystrophy. So, it's important to be vaccinated for pneumonia and to keep up to date with influenza shots. Try to avoid contact with children or adults who have an obvious infection.

For more information