Children with Duchenne muscular dystrophy (DMD) are often late walkers.
In toddlers, parents may notice enlarged calf muscles. This enlargement is known as pseudohypertrophy, or “false enlargement,” because the muscle tissue is abnormal and may contain scar tissue.
A preschooler with DMD may seem clumsy and fall often. Parents also may note that children have trouble climbing stairs, getting up from the floor or running.
By school age, children may walk on their toes or the balls of their feet with a slightly waddling gait, and fall frequently. To try to keep their balance, they may stick out their bellies and pull back their shoulders. Children also have difficulty raising their arms.
Lack of dystrophin can weaken the muscle layer in the heart (myocardium), resulting in a condition called cardiomyopathy. Over time, sometimes as early as the teen years, the damage done by DMD to the heart can become life-threatening. The heart should be monitored closely, usually by a pediatric cardiologist.
Beginning at about 10 years of age, the diaphragm and other muscles that operate the lungs may weaken, making the lungs less effective at moving air in and out. Although the child may not complain of shortness of breath, problems that indicate poor respiratory function include headaches, mental dullness, difficulty concentrating or staying awake, and nightmares.
Weakened respiratory muscles make it difficult to cough, leading to increased risk of serious respiratory infection. A simple cold can quickly progress to pneumonia. It’s important to get flu shots, and when infections occur, to get prompt treatment.
The muscle deterioration in Duchenne MD isn’t usually painful in itself. Some people report muscle cramps at times; these usually can be treated with over-the-counter pain relievers.
Because muscular dystrophy doesn’t affect nerves directly, touch and other senses are normal.
Many children with DMD begin using a wheelchair sometime between ages 7 and 12. Transition to a wheelchair usually is a gradual process; at first, the chair may be required only to conserve the child’s energy when covering long distances. (Children often experience renewed independence once they fully transition to a power wheelchair.)