Muscular Dystrophies Health Channel

Definition

Muscular dystrophy is a group of disorders that involve progressive muscle weakness and loss of muscle tissue.

Alternative Names

Inherited myopathy; MD

Causes, incidence, and risk factors

The group of diseases called muscular dystrophies (MD) includes many inherited disorders, such as:

• Becker's muscular dystrophy
• Duchenne muscular dystrophy
• Facioscapulohumeral muscular dystrophy
• Limb-girdle muscular dystrophy
• Emery-Dreifuss muscular dystrophy
• Myotonic dystrophy
• Myotonia congenita

Lambert-Eaton syndrome and myasthenia gravis also have symptoms that may be similar to early stages of some types of muscular dystrophies, so these disorders must be ruled out before muscular dystrophy is diagnosed.

Symptoms

Symptoms vary with the different types of muscular dystrophy. Some types, such as Duchenne muscular dystrophy, are deadly, while other types cause little disability and are associated with normal life span.

The muscles affected vary, but can be around the pelvis, shoulder, face or elsewhere. Muscular dystrophy can affect adults, but the more severe forms tend to occur in early childhood.

Symptoms include:

• Muscle weakness that slowly gets worse
  • Frequent falls
  • Delayed development of muscle motor skills
  • Problems walking (delayed walking)
  • Difficulty using one or more muscle groups
  • Eyelid drooping (ptosis)
  • Drooling
• Mental retardation (only present in some types of the condition)
• Hypotonia (low muscle tone)
• Joint contractures (clubfoot, clawhand, or others)
• Scoliosis (curved spine)

Some types of muscular dystrophy involve the heart muscle, causing cardiomyopathy or arrhythmias.

Signs and tests

A physical examination and your medical history will help the doctor determine the type of muscular dystrophy. Specific muscle groups are affected by different types of muscular dystrophy.

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

A muscle biopsy may be used to confirm the diagnosis. In some cases, a DNA blood test may be all that is needed.

Other tests may include:

• Serum CPK
• EMG (electromyography)
• ECG (electrocardiography)

This disease may also alter the results of the following tests:

• Myoglobin - urine/ serum
• LDH
• Creatinine
• AST
• Aldolase

Treatment

There are no known cures for the various muscular dystrophies. The goal of treatment is to control symptoms.