Overview of Muscular Dystrophy

For decades, muscular dystrophy has been associated with Jerry's kids. That is, Jerry Lewis, surrounded by children during the annual Muscular Dystrophy Association's Labor Day Telethon. From 1966 to 2010, Jerry Lewis hosted this annual telethon to benefit those with muscular dystrophy. Muscular dystrophy (MD) represents a group of nine inherited muscle disorders.

The telethon went on without Lewis from 2010 to 2014, ultimately ending in 2015.

Even though the annual telethon is over, muscular dystrophy—all nine forms—still exists. MD presents with a combination of muscle weakness and muscle wasting.

Symptoms

The characteristic symptom throughout all types of muscular dystrophy is progressive muscle weakness, though, the muscle groups affected can vary by age and the form of muscular dystrophy a person has. Here are the symptoms listed by the type:

Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is the most common childhood form of muscular dystrophy, with symptoms typically beginning between two to six years of age. DMD is inherited as an X-linked disorder, so it mostly affects boys. However, girls can carry the condition and may be mildly affected.

DMD affects approximately 1 in every 3,500 live male births (about 20,000 new cases each year), and it impacts children of all ethnic backgrounds.

The gene for DMD causes an absence of dystrophin, a protein that helps keep muscle cells intact. This means that muscle cells are easily damaged and become weak over time.

The first signs of DMD may include:

  • Frequent falling
  • Difficulty getting up from sitting or lying down
  • Problems climbing stairs
  • A waddle-like walk
  • Weakness in the legs and pelvis 
  • The appearance of enlarged calf muscles 
  • Struggling to lift the head, or has a weak neck
  • Standing and walking with chest and stomach stuck out (or has a sway back)
  • Walking hands up legs instead of standing straight up (called the Gower maneuver)

Eventually, DMD affects all the muscles in the body, including the heart and breathing muscles, so as the child grows older symptoms may include fatigue, heart problems due to an enlarged heart, weakness in the arms and hands, and loss of ability to walk by age 12.

The disease progresses slowly, but walking assistance will ultimately become necessary—leading up to a wheelchair. Respiratory infections like pneumonia may occur, which can be difficult for people with DMD to fight. Thanks to advances in research and technology, the life expectancy for DMD has increased into the early 30s.

Becker Muscular Dystrophy

Becker muscular dystrophy is very similar to DMD, except that the symptoms of Becker MD can appear later in youth—up until as late as 25. Although similar to DMD, symptoms of Becker MD progress slower than those of DMD.

Congenital Muscular Dystrophy

Congenital muscular dystrophy represents a group of muscular dystrophies that are present at birth.

This form of MD can affect both boys and girls. Not all congenital forms have been identified. One form, Fukuyama congenital muscular dystrophy, causes severe weakness of the facial muscles and limbs and may include joint contractures, mental and speech problems, as well as seizures.

Emery-Dreifuss Muscular Dystrophy

Emery-Dreifuss muscular dystrophy is a less common form of childhood MD that only affects boys. This form progresses slowly. However, unlike DMD, contractures—muscle shortening—may appear earlier in life. Overall muscle weakness is also less severe than that of DMD. Serious heart problems associated with Emery-Dreifuss MD may require a pacemaker.

Limb-Girdle Muscular Dystrophy

Limb-girdle muscular dystrophy begins in the teen or early adult years of both genders. The disease causes muscle weakness that starts in the hips, moves to the shoulders, and extends outwards into the arms and legs. The disease progresses slowly but eventually leads to difficulty walking.

Facioscapulohumeral Muscular Dystrophy

Facioscapulohumeral muscular dystrophy (FSH MD) begins in adolescence or early adulthood and affects both genders. FSH MD primarily affects the muscles of the face ("facio-"), shoulder blades ("scapulo-"), and upper arms ("humeral"). People with FSH MD have shoulders that slope forward, making it difficult to raise their arms over their head. Muscle weakness continues throughout the body as the disease progresses. FSH MD can range from very mild to severe. Despite the progressive muscle weakness, many people with FSH MD are still able to walk.

Myotonic Muscular Dystrophy

Myotonic muscular dystrophy (Steinert's disease) is the most common form of adult muscular dystrophy. This form of muscular dystrophy starts with muscle weakness in the face and then moves on to the feet and hands. Myotonic MD also causes myotonia—the prolonged stiffening of muscles (like spasms), and it’s a symptom that only occurs in this form of MD. Myotonic MD affects the central nervous system, heart, digestive tract, eyes, and endocrine glands. It progresses slowly, with the amount of muscle weakness varying from mild to severe. A woman with myotonic MD can give birth to an infant with a congenital form of the disease.

Oculopharyngeal Muscular Dystrophy

Oculopharyngeal muscular dystrophy generally begins in the fourth or fifth decade of life. Drooping eyelids are typically the first sign of this form of dystrophy. The condition then progresses to facial muscle weakness and difficulty swallowing. Surgery can reduce swallowing problems and prevent choking as well as pneumonia.

Distal Muscular Dystrophy

Distal muscular dystrophy includes a number of muscle diseases which begin in adulthood and have similar symptoms of weakness of the forearms, hands, lower legs, and feet. These diseases, including subforms Welander, Markesbury-Griggs, Nonaka, and Miyoshi, are less severe and involve fewer muscles than other types of muscular dystrophy. Distal form affects both men and women.

Causes

The disease is progressive, and it's linked to gene variants (mutations) that impede the synthesis and regulation of proteins that are responsible for the formation and function of muscle development, according to the Cleveland Clinic. Researchers have discovered more than 30 genes responsible for causing different types of MD.

Diagnosis

DMD, in particular, is usually based on the development of the symptoms in the child’s preschool years. Parents or teachers begin to notice the boy having difficulty climbing stairs or keeping up with other children.

The National Institute of Health (NIH) lists several tests a healthcare provider may use to diagnose MD and determine the type. Those tests include:

  • Blood tests to measure specific enzymes related to the breakdown of muscle fibers and sugar. For example, a blood test for creatine kinase (CK or CPK) may show elevated levels that are 10 to 100 times normal. This test indicates that muscle damage is occurring but does not confirm the diagnosis.
  • Muscle biopsies to examine muscle tissue under a microscope and evaluate the number of genes contributing to MD.
  • Genetic testing to assess gene variants, which can lead to Duchenne or Becker MD. Also, genetic testing can evaluate whether women with a family history of Duchenne or Becker MD are carriers as well.
  • Neurological tests can help rule out the presence of other neurological disorders. Additionally, neurological testing will evaluate muscle weakness, reflexes, coordination, and more.
  • Cardiac tests may be used to gather information about whether or not there is impairment in heart function.  
  • Exercise assessments may be performed to check a person’s strength, respiratory function, and the levels of certain chemicals (like nitric oxide) after exercise has taken place.
  • Imaging, such as MRI and ultrasounds, might be used to take pictures and gather insights about the quality and density of muscle tissue.  

Treatment

Treatments for muscular dystrophy are aimed at keeping people strong and mobile for a long as possible and manage other conditions that may develop as a result of a weakening musculoskeletal system.

Medications

Medications like steroids and other immunosuppressant drugs may be used to slow the progression of the disease, improve energy and lessen the symptoms, but they have serious side effects when taken for a long time. Anticonvulsant medications may be used to reduce seizures and diminish muscle spasms. If there’s an overlapping condition present, such as a heart issue or an infection, a healthcare provider may prescribe heart medications or antibiotics. Furthermore, for people who’ve been diagnosed with DMD, there’s one drug that’s approved by the Food and Drug Administration (FDA) called, Eteplirsen, or Exondys 51. It’s specifically indicated to treat patients who have a genetic variant leading to a dystrophin protein deficiency.

Therapy

Therapies like physical, occupational, speech, and respiratory can be instrumental in helping people maintain their range of motion, mobility, activities of daily living, speech and communication, swallowing, and lung function. Additionally, these therapies can provide assistive devices such as braces, canes, walkers, and wheelchairs to support weakened muscles.

Surgery  

The NIH reports patients with MD may need to undergo surgery to correct a variety of issues. The types of surgeries can include an insertion of a pacemaker when heart problems are present, surgery to improve spinal alignment when a curvature of the spine (scoliosis) interferes with breathing, and surgery to remove cataracts from the eyes and improve vision. In cases of DMD, some patients may need to have a tracheostomy tube surgically placed in their trachea (windpipe) due to the severity of breathing problems, and some may require a respirator. 

A Word From Verywell

Receiving a diagnosis of MD can be incredibly overwhelming. Although there’s currently no cure for MD, the medical community has made great strides in understanding the illness and improving the life expectancy and quality of life of those living with it. Whether you or a loved one have been diagnosed with MD (or you just want to learn more about it), arm yourself with as much information as possible so that you can make decisions that are right for you and your family’s healthcare.

Sources:

Full List of Muscular Diseases. Muscular Dystrophy Association website. https://www.mda.org/diseaseula

How is muscular dystrophy diagnosed? National Institute of Health website. https://www.nichd.nih.gov/health/topics/musculardys/conditioninfo/diagnosed

June Capossela Kempf. “The muscular dystrophy telethon now just a memory.” Newsday, 6 Sept. 2015.

Muscular Dystrophy. Cleveland Clinic website. https://my.clevelandclinic.org/health/diseases/14128-muscular-dystrophy