| Progression and Symptoms of DMD |
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The progression of Duchenne
MD leads to many physical symptoms that typically affect different
portions of the body, including the back (spine), legs, feet,
joints and tendons. |
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General Weakness : |
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General weakness and fatigue can be symptoms of Duchenne MD. Due
to the additional effort that boys with Duchenne MD put forth when
climbing stairs, running or even standing, they will often grow weak
from these routine tasks and complain that their legs are tired. As
Duchenne MD continues to weaken muscles, boys will often have to use
their arms to get up from a sitting position. Usually they will experience
a range in their levels of strength and fluctuate between good days
and bad days. |
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Overdeveloped Calves |
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One of the early indicators of Duchenne MD is an enlargement or
overdevelopment of the calves, also known as 'pseudohypertrophy'.
During exercise, most people experience muscle hypertrophy, or enlargement
of the muscles. Boys with Duchenne MD also experience this enlargement,
initially. But instead of getting stronger, Duchenne MD causes the
muscles to soon become permanently damaged and die due to the damaged
or missing dystrophin gene (the glue that holds muscles together).
As this is happening, there are other cells that may respond by producing
fibrous connective tissue with fatty deposits. This increases the
volume of the muscle and causes it to become enlarged due to a bulking
of the muscle by fat, not by muscle cells. |
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Lordosis |
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The spine is a column of small bones, or vertebrae that supports
the entire upper body. This column is made up of three sections of
vertebrae: the five bones that support the neck, the twelve bones
that support the rib cage and the five lowest and largest bones that
support the lumbar. Most of the body's weight and stress falls on
the lumbar vertebrae.
Lordosis is the curvature of the lumbar and cervical spine. The term
is also used to refer to any condition characterized by an excessive
curvature of the spine, with the bend towards the front (hollow back,
saddle back and sway back). It affects the lumbar region, between
the ribs and the pelvis) and is the opposite of hunchback. Lordosis
is commonly found in pregnant women and obese people with weak back
muscles and heavy abdomens. It also affects boys with Duchenne MD.
As their back muscles become weaker, Lordosis cause their bodies to
lean forward, and a curvature of the spine results. |
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Feet |
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Often boys with Duchenne MD will have problems with their feet.
This occurs as muscle weakness spreads and the Achilles tendons (heel
cords that anchor the muscles at the back of the lower leg to the
heel bone) are often contracted, pulling feet into an abnormal position
and interfering with the ability to walk. Frequently, boys with Duchenne
MD will wear ankle-straightening splints at night to help keep their
feet straight.
Other foot problems relating to Duchenne MD include a purple discoloration
of the feet and/or suffering from cold feet. This happens as the muscle
function of the legs and feet decrease. Active muscles require a high
blood flow to provide nourishment, and the reverse holds true: inactive
muscles do not need as much blood flow. The cardiovascular system
automatically adjusts in order to send blood where it is needed most
throughout the body, so the blood is diverted to the organs that need
it most, like the kidneys and the brain. |
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Joint and Tendon Cord Elasticity |
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Joint and tendon restriction is another symptom that boys with Duchenne
may suffer from. This is called 'contracture'. It typically affects
the ankles first, followed by the hips and knees, and finally, the
joints of the upper limbs. Physiotherapy and occupational therapy
are often used to help offset this. A variety of exercises that stretch
the joints and advice on good and bad sitting positions and activities
may be employed to cultivate elasticity. |
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Scoliosis |
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Scoliosis is a three-dimensional curvature of the spine. It most
commonly develops in the area between the mid and lumbar portion of
the spine. If severe, scoliosis can be disfiguring and eventually
limit the function of the lungs and upper limbs. Increasingly, boys
who have Duchenne MD are turning to surgery to help straighten their
spines. In this major operation, doctors insert a metal rod to keep
the spine straight. The optimal time for boys with scoliosis to have
this surgery is generally believed to be between ages 11 and 13. |
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Speech/Intellectual Handicaps |
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Due to dystrophin abnormalities in the brain that cause subtle cognitive
and behavioral deficits, intellectual handicaps are more frequent
in boys with Duchenne MD than in the general population, but still
only affect a small percentage. About one third of boys with Duchenne
MD have some degree of a learning disability, although only a few
have severe cases of retardation. And unlike progressive muscle weakness,
when a learning disability does occur in a boy with Duchenne MD, it
never worsens as time goes on. Whatever intelligence he has at birth,
he maintains throughout his life unless he is affected by another
ailment.
For boys who suffer from both Duchenne MD and learning disabilities,
language and communication skills are typically the main concern.
But manual skills, visual skills and creativity are often excellent
in boys with Duchenne MD, which is perhaps why many become very good
artists. |
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Respiratory Problems |
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Duchenne MD causes many changes throughout the body. The lungs are
affected by these changes. Respiratory function usually remains normal
until around age 10. Afterwards, respiratory muscle function may begin
to decline enough to change the way lungs pull air in and push it
out. The diaphragm sits below the lungs and is the muscle responsible
for this crucial movement of air. As Duchenne MD progresses, the diaphragm
becomes weakened (due to scar tissue buildup) and breathing becomes
more difficult. At the same time, muscles responsible for coughing
are also growing weaker and are not able to support the diaphragm.
As a result, the amount of oxygen in the blood decreases and is replaced
by carbon dioxide as the exchange of air becomes more and more difficult
for the lungs. This can lead to symptoms like headaches, mental lapses,
and difficulty concentrating or staying awake during the day. In addition
to the lung difficulties, the weakened muscles responsible for coughing
may permit bacteria and viruses to grow, because coughing is the normal
defense to rid the lungs of extra secretions. This may allow a simple
cold to quickly progress into pneumonia in boys with Duchenne MD |
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