Definition of Muscular dystrophy

Muscular dystrophy: One of 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.

The major forms of muscular dystrophy include:

• Duchenne muscular dystrophy
• Becker muscular dystrophy
• limb-girdle muscular dystrophy
• facioscapulohumeral muscular dystrophy
• congenital muscular dystrophy
• oculopharyngeal muscular dystrophy
• distal muscular dystrophy
• Emery-Dreifuss muscular dystrophy and
• myotonic dystrophy.

Muscular dystrophy can affect people of all ages. Although some forms first become apparent in infancy or childhood, others may not appear until middle age or later. Duchenne muscular dystrophy is the most common kind of muscular dystrophy affecting children. Myotonic dystrophy is the most common of these diseases in adults.

There is no specific treatment for any of the forms of muscular dystrophy. Physical therapy to prevent contractures (a condition in which shortened muscles around joints cause abnormal and sometimes painful positioning of the joints), orthoses (orthopedic appliances used for support) and corrective orthopedic surgery may be needed to improve the quality of life in some cases. The cardiac problems that occur with Emery-Dreifuss muscular dystrophy and myotonic dystrophy may require a pacemaker. The myotonia (delayed relaxation of a muscle after a strong contraction) occurring in myotonic dystrophy may be treated with medications such as phenytoin or quinine.

The prognosis (outlook) with muscular dystrophy varies according to the type of muscular dystrophy and the progression of the disorder. Some cases may be mild and very slowly progressive with normal lifespan, while other cases may have more marked progression of muscle weakness, functional disability and loss of ambulation. Life expectancy depends on the degree of progression and late respiratory deficit. In Duchenne muscular dystrophy, death usually occurs in the late teens to early 20s.

Muscular dystrophy is abbreviated as MD.