Definition

Muscular dystrophy is a group of inherited, progressive muscle disorders. All forms cause progressive weakness and degeneration of the muscles that control movement. Some also affect the heart or other organs. Age of onset is between infancy to adulthood. The different forms include:

• Duchenne dystrophy, which is the most common
• Becker dystrophy, which is a milder form of Duchenne dystrophy
• Myotonic muscular dystrophy, which can begin in late adulthood
• Facioscapulohumeral muscular dystrophy, which affects the muscles of the face, shoulder blades, and upper arms
• Congenital muscular dystrophy, which is diagnosed on or near birth and results in overall muscle weakness
• Distal muscular dystrophy, which affects the distal muscles of the lower arms, hands, lower legs, and feet
• Emery-Dreifuss muscular dystrophy, which affects the muscles of the shoulders, upper-arms, and calf muscles
• Limb-girdle muscular dystrophy, which affects the muscles around the hips and shoulders
• Oculopharyngeal muscular dystrophy, which affects swallowing and the ability to keep the eyes open

Causes

This condition is caused by defects in genes that control muscle development and function. In some cases, the genes are passed from parent to child. In other cases, the genetic mutation occurs spontaneously.

Risk Factors

Males are at increased risk for Duchenne dystrophy and Becker dystrophy. Factors that increase your chance of developing muscular dystrophy. Tell your doctor if you have any of these risk factors:

The risk of muscular dystrophy is increased if you have a family member with muscular dystrophy.

Symptoms

Each type of muscular dystrophy has its own unique symptoms. For example, the muscles that are affected may differ depending upon the type.

Symptoms common to most forms of muscular dystrophy may include:

Initial symptoms:

• Progressive weakening of muscles
• Enlargement of muscles as they weaken
• Muscle cramping
• Clumsiness
• Frequent falling and difficulty getting up

Later symptoms:

• Muscle contraction and stiffening
• Muscle deterioration

Symptoms specific to Duchenne and Becker dystrophy include:

• Initial symptoms:
  • Usually muscles closest to the trunk become weak first. Then, muscles further away weaken as the disease advances.
  • Enlargement of calf muscles as they weaken
• Later symptoms
  • Abnormally curved spine
  • Respiratory infections
  • Severe muscle deterioration, usually leading to use of a wheelchair
  • Difficulty breathing
  • Muscle contraction and stiffening—often severe
  • Distortion of the body
  • Reduced intelligence

Symptoms specific to myotonic muscular dystrophy include:

• Difficulty letting go after a handshake
• Reduced intelligence
• Excessive sleeping

Symptoms usually become worse over time. In many forms, life expectancy is shortened.

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done.

Your blood may be tested for evidence of muscle damage

A muscle biopsy will identify the

type of muscular dystrophy

Your muscles and nerves may be tested. This can be done with:

• Electromyogram (EMG)
• Nerve conduction study (NCS)

Treatment

There is no cure for muscular dystrophy. However, treatment may help improve the symptoms.

Treatment may consist of:

Prevention

Muscular dystrophy is an inherited disease. Get genetic counseling if you are concerned about having a child with muscular dystrophy, especially if you:

• Have muscular dystrophy or a family history of the disease
• May be a carrier of the gene for muscular dystrophy
• Have a partner with a family history of the disease

Muscular Dystrophy Family Foundation http://www.mdff.org

Muscle Dystrophy Canada http://www.muscle.ca

Amato AA, Griggs RC. Overview of the muscular dystrophies. Handb Clin Neurol. 2011;101:1-9.

Congenital muscular dystrophy. Muscular Dystrophy Association website. Available at:
http://www.mda.org/disease/congenital-muscular-dystrophy
Accessed June 23, 2015.

Distal muscular dystrophy. Muscular Dystrophy Association website. Available at:
http://mda.org/disease/distal-muscular-dystrophy
Accessed June 23, 2015.

Emery-dreifuss muscular dystrophy. Muscular Dystrophy Association website. Available at:
http://mda.org/disease/emery-dreifuss-muscular-dystrophy
Accessed June 23, 2015.

Escolar DM, Hache LP, et al. Randomized, blinded trial of weekend vs daily prednisone in Duchenne muscular dystrophy. Neurology. 2011;77(5):444-452.

Facioscapulohumeral muscular dystrophy. Muscular Dystrophy Association website. Available at:
http://mda.org/disease/fsh-muscular-dystrophy
Accessed June 23, 2015.

Limb-girdle muscular dystrophy. Muscular Dystrophy Association website. Available at:
http://mda.org/disease/limb-girdle-muscular-dystrophy
Accessed June 23, 2015.

NINDS muscular dystrophy information page. National Institute of Neurological Disorders and Stroke website. Available at:
http://www.ninds.nih.gov/disorders/md/md.htm
Updated June 22, 2015. Accessed June 23, 2015.

Oculopharyngeal muscular dystrophy. Muscular Dystrophy Association website. Available at:
http://mda.org/disease/oculopharyngeal-muscular-dystrophy/overview
Accessed June 23, 2015.