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Distal Muscular Dystrophy
Distal MD is the rarest type of muscular dystrophy. This form of MD is
actually a group of autosomal-dominant inherited diseases that have in common
their weakening effects on the distal muscles. The distal muscles are those of
the extremities, (distal meaning farthest from the center) and include muscles
in the hands, forearms, lower legs and feet. The onset of Distal MD is generally
between the ages of 40 and 60, and the primary symptom is weakness in the hands
and other affected muscles.
Although its course can be variable, Distal MD is generally slower in
progression than other dystrophies. It is also generally less severe and affects
fewer muscles than other dystrophies.
Diagnosis
After carefully evaluating a patient’s medical history, the doctor will
perform a thorough physical exam to rule out other causes. If MD is suspected,
there are a variety of laboratory tests that can be used to solidify a
diagnosis. These tests may include:
Blood tests: When blood tests are performed to test for MD, the doctors
are looking for an enzyme called creatine kinase (CK). This enzyme rises in the
blood due to muscle damage or deterioration and may reveal some forms of MD
before any physical symptoms appear.
Muscle biopsy: During a muscle biopsy, a small piece of muscle tissue is
removed and then examined under a microscope. If MD is present, changes in the
structure of muscle cells and other characteristics of the different forms of MD
can be detected. The sample can also be stained to detect the presence or
absence of particular proteins.
Electromyogram (EMG): An EMG is a test that measures the muscle’s
response to stimulation of its nerve supply (nerve conduction study) and the
electrical activity in the muscle (needle electrode examination). Both
components of the EMG are very useful in diagnosing MD.
Genetic tests: Several of the muscular dystrophies can be positively
diagnosed by testing for the mutated gene involved. These include Duchenne,
Becker, Distal and some forms of Limb-girdle and Emery-Dreifuss dystrophies.
Treatment
There is no cure for muscular dystrophy, although some drugs still in the
trial stage have shown promise in slowing or delaying the progression of the
disease. For the time being, treatment is aimed at preventing complications due
to the effects of weakness, decreased mobility, contractures, scoliosis, heart
defects and respiratory weakness.
Physical therapy: Physical therapy, especially regular stretching, is
important in helping to maintain the range of motion for affected muscles and to
prevent or delay contractures. Strengthening other muscles to compensate for
weakness in affected muscles may be of benefit also, especially in earlier
stages of milder MD. Regular exercise is important in maintaining good, overall
health, but strenuous exercise may damage muscles further. For patients whose
leg muscles are affected, braces may help lengthen the period of time that they
can walk independently.
Surgery: If a patient’s contractures have become more pronounced,
surgery may be used to relieve the tension by cutting the tendon of the affected
muscle then bracing it in a normal resting position while it regrows. Other
surgeries are used compensate for shoulder weakness in facioscapulohumeral MD,
and to keep the breathing airway open for people with distal MD who sometimes
experience sleep apnea. Surgery for scoliosis is often needed for patients with
Duchenne MD.
Occupational therapy: Occupational therapy involves employing methods and
tools to compensate for a patient’s loss of strength and mobility. This may
include modifications at home, dressing aids, wheelchair accessories and
communication aids.
Nutrition: Nutrition has not been shown to treat any conditions of MD,
but it is essential to maintaining good health.
Cardiac care: Arrhythmias are often a symptom with Emery-Dreifuss and
Becker MD and may need to be treated with special drugs. Pacemakers may also be
needed in some cases and heart transplants are becoming more common for men with
Becker MD.
Respiratory care: When the muscles of the diaphragm and other respiratory
muscles become too weak to function on their own, a patient may require a
ventilator to continue breathing deeply enough. Air may also be administered
through a tube or mouthpiece. It is therefore very important to maintain healthy
lungs to reduce the risk of respiratory complications.
Like many other disorders, understanding and education about muscular
dystrophy is the most important tool with which to manage and prevent
complications. The following organizations can provide more information about
muscular dystrophy:
The Muscular Dystrophy Association
National Headquarters
3300 E. Sunrise Drive
Tucson, AZ 85718
(800) 572-1717
www.mda.org
Muscular Dystrophy Family Foundation
615 North Alabama Street
Suite 330
Indianapolis IN 46204-1213
(800) 544-1213
www.mdff.org
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