Understanding DMD Symptoms

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The progression of DMD leads to many physical symptoms that typically affect different portions of the body, including the back (spine), legs, feet, joints and tendons.

The progression of symptoms (in order of occurrence) are:


General weakness and fatigue can be symptoms of DMD. Due to the additional effort that young men with DMD 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 DMD continues to weaken muscles, young men 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.

One of the early indicators of DMD is an enlargement or overdevelopment of the calves, also known as 'pseudohypertrophy'. During exercise, most people experience muscle hypertrophy, or enlargement of the muscles. Young men with DMD also experience this enlargement, initially. But instead of getting stronger, DMD 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.

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 young men with DMD. As their back muscles become weaker, Lordosis cause their bodies to lean forward, and a curvature of the spine results.

Often young men with DMD 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, young men with DMD will wear ankle-straightening splints at night to help keep their feet straight.

Other foot problems relating to DMD 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.

Joint and tendon restriction is another symptom that young men 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.

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, young men who have DMD 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 young men with scoliosis to have this surgery is generally believed to be between ages 11 and 13.

Due to dystrophin abnormalities in the brain that cause subtle cognitive and behavioral deficits, intellectual handicaps are more frequent in young men with DMD than in the general population, but still only affect a small percentage. About one third of young men with DMD 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 DMD, 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 young men who suffer from both DMD and learning disabilities, language and communication skills are typically the main concern. But manual skills, visual skills and creativity are often excellent in young men with DMD, which is perhaps why many become very good artists.

DMD 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 DMD 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 young men with DMD.




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