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Muscular dystrophy

The muscular dystrophies are a group of genetic and hereditary myopathies that are characterized by progressive muscle weakness and loss of muscle tissue and caused by defects in structural muscle proteins.

Major types are Duchenne and Becker muscular dystrophies, myotonic dystrophy, limb-girdle dystrophy, fascioscapulohumeral muscle dystrophy and severe childhood autosomal recessive muscular dystrophy. The most frequent symptoms are muscle weakness (frequent falls, walking problems, eyelid drooping), skeletal and muscle deformities. Neurologic examination often reveals loss of muscle tissue (wasting), muscle contracture, pseudohypertrophy and weakness. Diagnosis is usually established by muscle biopsy, elevated serum CK levels and electromyography examination, which is consistent with myogenic involvement. Some types of muscular dystrophy may present with additional cardiac disease, intellectual deterioration and infertility. There is no known cure for muscular dystrophy. Inactivity (such as bedrest and even sitting for long periods) can worsen the disease. Physical therapy and orthopedic instruments (e.g. wheelchairs) may be helpful.


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What is Muscular Dystrophy (MD)?

Muscular dystrophy (MD) refers to 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 MD, and a few forms involve other organs as well. The major forms of MD include myotonic, Duchenne, Becker, limb-girdle, facioscapulohumeral, congenital, oculopharyngeal, distal and Emery-Dreifuss. Duchenne is the most common form of MD affecting children, and myotonic MD is the most common form affecting adults. MD 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.

Is there any treatment?

There is no specific treatment for any of the forms of MD. 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 MD and myotonic MD may require a pacemaker. The myotonia (delayed relaxation of a muscle after a strong contraction) occurring in myotonic MD may be treated with medications such as phenytoin or quinine.

What is the prognosis?

The prognosis of MD varies according to the type of MD 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 may depend on the degree of progression and late respiratory deficit. In Duchenne MD, death usually occurs in the late teens to early 20s.

What research is being done?

The NINDS supports a broad program of research on MD. The goals of these studies are to increase understanding of MD and its cause(s), develop better therapies, and, ultimately, find ways to prevent and cure the disorder.

Contains material originally from public domain NIH document at http://www.ninds.nih.gov/health_and_medical/disorders/md.htm



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