WHAT TO EXPECT IN DMD
Parents understandably want to know what to expect when their child has received a diagnosis of a serious illness. In addition to your doctor's advice and counsel, you may wish to consult one of the many excellent books on the market, to read MDA's pamphlets about the disease and its effect on the family, and to attend an MDA-coordinated support group in your area. Talking to parents and children who have "been there" can be an enormous comfort, even if the news isn't always good. You'll probably find yourself helping someone else at some point in the course of your son's illness. (Throughout this guide, we refer to boys and sons with DMD. Girls can also have this disorder, but very rarely do. See Chapter 1 for an explanation.)
The course of DMD is fairly predictable, although it's important to bear in mind that there are always individual variations from the "average."
The onset of symptoms of Duchenne is sometimes hard to pinpoint, although many parents whose children are later given this diagnosis will recall that their son was late in learning to walk. In one survey of affected boys, about half weren't walking at 18 months, an age when most children have mastered walking.
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| Two of the obvious symptoms of MD are enlarged calves and a waddling gait. |
During the toddler years, parents may notice that the child's calf muscles are enlarged. This is the so-called pseudohypertrophy (false enlargement) associated with these muscles in DMD. The muscles look bigger but feel rubbery and have abnormal characteristics in the tissue. The enlargement is unlikely to alarm parents unless they've seen it before and associate it with the diagnosis.
Parents may also note that the boy is clumsy and falls often. This is hardly unusual in a new walker, and even your pediatrician may remain unconcerned at this early stage.
As time goes on, however, the falls clearly begin to look more ominous. By the age of 3 or 4, the boy can't keep up with his peers, has trouble with climbing stairs or playground equipment or getting up from the floor, and usually can't manage to run. Jumping from a standing position with both feet is almost always impossible. As one doctor put it, "The feet remain glued to the ground."
By school age, the problem is obvious. The child has trouble walking, mostly because the quadriceps muscles, the large "lap" muscles in the front of the thighs, are weakening, keeping him off balance as he tries to shift his weight. To compensate, the boy contracts the muscles in the back of the lower leg (calf muscles), which in turn causes the foot to go down and the toes to point. He may walk on his toes or balls of his feet, with a slightly rolling gait. At this point, some doctors who aren't familiar with DMD may refer the child to an orthopedist or physical therapist for his "tight heel cords," or tell the parents the child has an odd habit that he'll outgrow.
As the muscles that allow him to stand straight weaken, the boy feels himself falling forward and tries to compensate by sticking his belly out and putting his shoulders back, all in an effort to keep his balance. Still, he'll probably have a waddling and unsteady gait, and can easily fall over.
If the boy is asked to get up from the floor, he'll usually use a "butt-first" maneuver, sticking his posterior up in the air and then "walking" up his legs with his hands, leaning on his arms for support. The medical term for this is Gowers' maneuver (see illustration)and, while not specific to DMD, it's a good indicator of muscle weakness in the legs.
The shoulder muscles are also weakening, so the child has difficulty raising his arms.
By now, the pediatrician's reassurances have changed to anxious looks. A referral is made to a neurologist, and the diagnosis is usually a simple matter from there.
By the way, try not to blame your pediatrician or family doctor if you like and respect him or her in general. Muscular dystrophy is not a common disorder, and many doctors will never have seen it before. An early diagnosis wouldn't have changed the course of the disease (though it might have affected your family planning), so it's best to get straight to your MDA clinic for the muscular dystrophy specialist and keep up your relationship with your primary care doctor for the rest of your child's care. You'll still want your child to have a pediatrician or family practitioner, because you can't expect the neurologist to be on top of the child's immunizations or general health care.
You may be relieved to know that the muscle deterioration itself isn't usually painful, although some children report muscle cramps at times. Cramps and discomfort can also occur when contractures aren't properly treated (see "Staying Flexible, Upright and Mobile"). Since muscular dystrophy doesn't affect nerves directly, boys with it retain normal sensations from touch and other senses.
In addition to the skeletal muscle problems, boys with DMD often have some heart muscle problems. These may or may not need special attention, but they should be monitored by your doctor, who may in turn refer you to a pediatric cardiologist. Make sure the doctors are communicating with each other. (see "Cardiac Problems are Common"for more on heart problems.)
Later in the disease, involvement of the respiratory muscles poses the most serious risk to life. At this point, other specialists may need to be involved. (see "Preserving Respiratory Function" for more on respiratory problems.)
About a third of boys with DMD have some degree of intellectual impairment or learning disabilities. (see "Learning Disabilities" for more.)
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| As a boy with DMD gets older, his spine curves inward. |
The loss of muscle function in boys with Duchenne is progressive, but the rate of change isn't always perfectly even. Sometimes things happen rapidly; sometimes there's a plateau for a few months.
Sometimes, between ages 3 and 6, there seems to be an improvement in muscle function. The boy's muscle growth may temporarily outstrip the progress of the disease, giving a cruelly false impression that things may turn out all right after all, that the child has the wrong diagnosis, or that a special diet is working. Unfortunately, the downward slope of muscle function resumes in time, with nearly all children losing the ability to walk sometime between the ages of 7 and 12.
In 1983, a large MDA-sponsored study of the average course of DMD -- the "natural history" of the disease -- became available. MDA sponsored the study in order to develop a standard of comparison for future trials of various therapies.
The "milestones" representing loss of muscle function, shown in the chart below, come from that study.
| Milestone |
Average Age |
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| Loses ability to get up from a chair |
9 years, 5 months |
| Loses ability to get up from floor |
10 years, 2 months |
| Loses ability to climb stairs |
10 years, 5 months |
| Walks only with assistance or with braces |
10 years, 10 months |
| Cannot walk 30 |
11 years, 5 months |
| Needs wheelchair full time |
12 years, 4 months |
Although physical therapy, braces, respiratory therapy, surgery and the steroid drug prednisone may alter this natural history to some extent, these milestones remain reliable today. As with all statistics, keep in mind that these numbers are only averages. They can't predict exactly when an individual child will lose a particular function or how long one person will survive.
Few studies like this one have gone much beyond age 12, perhaps because the disease course becomes less predictable after this point. However, in most boys with DMD, the teen years will involve significant loss of skeletal muscle strength, so that all activities involving the arms, legs or trunk require assistance or mechanical support. For example, by the late teens (sometimes earlier), many boys will need help to turn over in bed. However, most boys retain at least some function in their fingers, so that they can continue to operate a computer or use a writing tool.
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| By the time he's about 12, he'll need a wheelchair at least part of the time. |
Fixations of the joints, known as contractures, become more prominent, and spinal curvatures, if they have not been surgically remedied by the teens, can be severe.
In the teen years, loss of respiratory muscle power and cardiac complications because of damage to the heart muscle are the primary threats to health and life. Careful monitoring and treatment of cardiac problems and use of ventilatory assistance have increased the quality and quantity of life for boys with DMD in recent years.
Death usually comes sometime between the teens and the 30s, most often following a period of declining respiratory or cardiac function.
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