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Muscular dystrophy (MD) is a group of rare diseases that cause muscle fibers to weaken and break down. MD affects the skeletal or voluntary muscles that control movement in the arms, legs, and trunk. It also can affect the heart and other involuntary muscles, such as those in the gut. MD passes from parent to child (genetic) and worsens over time (progressive).
There are nine major types of MD affecting people of all ages, from infancy to middle age or later. The two most common types of MD that affect children are Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD).
Both DMD and BMD affect boys almost exclusively; girls are rarely affected.
MD is a sex-linked recessive disease. It typically passes from a mother (who has no symptoms) to her son.
Both Duchenne MD and Becker MD cause weak muscles, lack of coordination, and progressive disability.
Duchenne Muscular Dystrophy
Duchenne MD begins with muscle loss in the pelvis, upper arms, and legs. The first signs and symptoms of DMD develop between ages 2 to 5 years. Symptoms include:
- Difficulty walking, such as lateness in learning how to walk (older than 18 months), having a waddling gait, or walking on the toes or balls of the feet
- Difficulty running or jumping because of weakness in leg muscles
- Frequent falls, stumbling, and difficulty climbing stairs
- Difficulty standing from a lying or sitting position
- Reduced endurance
- Enlarged calf muscles
- Mild mental retardation (in some patients)
Many children with DMD lose their ability to walk by late childhood and require wheelchairs. As muscles continue to weaken in the back and chest, most children develop curvature of the spine (scoliosis). By adolescence, DMD usually progresses to weaken the heart and respiratory muscles.
Becker Muscular Dystrophy
Becker MD begins with muscle loss in the hips, pelvis, thighs and shoulders. BMD is basically a milder form of Duchenne MD. Symptoms include:
- Physical difficulties similar to Duchenne muscular dystrophy
- Waddling gait, perhaps walking on toes or sticking out the abdomen to balance weak muscles
BMD progresses more slowly over the course of decades, and is a milder and less predictable disease. Some men with BMD need wheelchairs by age 30 years or later; others manage for many years with minor aids, such as a walking cane.
If you think your child may have MD, see your doctor as soon as possible for diagnosis and comprehensive care.
To diagnose MD, the doctor will take a complete medical history of your child and the family. The doctor will also perform a thorough physical examination of your child and may use laboratory tests to confirm the diagnosis of MD.
Tell the doctor if other family members have any signs or symptoms of MD. Be sure to mention if your child has any other health problems. Also, tell the doctor at what age your child achieved growth milestones, such as learning how to walk.
The doctor will want to see how your child stands up from a sitting position on the floor. Children with DMD use the Gower's maneuver to stand up. They start out on their hands and feet, planting their feet widely apart and pushing up their bottom first. Then they use their hands to push up on their knees and thighs. The doctor will also want to watch your child walk. He or she may carefully test the child's muscles and nervous system.
The doctor may use certain laboratory tests to confirm that your child has MD.
Blood tests. The doctor checks a blood sample for high levels of the enzyme creatine kinase, which can indicate muscle damage.
Electromyography. The doctor puts small electrodes into muscle to measure electrical activity. Changes in the pattern of activity can show disease.
Muscle biopsy. The doctor removes a small piece of muscle to study in the laboratory. This can distinguish various forms of MD from other muscle diseases.
Genetic testing. Sometimes, the doctor can study a blood sample to identify an abnormal gene and diagnose MD.
Duchenne MD has a more certain and severe disease process than Becker MD. Doctors do not yet have a cure for any type of MD. Fortunately, timely interventions can help slow progression of complications and maximize your child's quality of life.
The goals of nonsurgical treatment of MD include keeping the child's body flexible, upright, and mobile, and helping the child function independently for as long as possible.
The doctor may recommend various nonsurgical treatments:
- Physical therapy and bracing to prevent contractures. The doctor may prescribe daily stretching exercises to improve the child's ability to walk. Regular, moderate physical therapy may help maintain range of motion in stiff or "frozen" joints. Walking braces for the ankle-foot or the knee-ankle-foot can help support weak muscles and keep the body flexible, slowing progression of contractures.
- Medications. Sometimes a doctor may prescribe anti-inflammatory corticosteroid medications to improve muscle strength and delay progression of DMD. These medications can cause serious side effects.
- Assistive devices. Rehabilitative devices such as canes, walkers, wheelchairs, strollers, and electric wheelchairs can help maintain the child's mobility and independence. Sometimes it helps to make modifications to your home, such as widening doorways and installing wheelchair ramps. Eventually, as respiratory muscles weaken, the child may also need the assistance of a breathing device, or ventilator.
- Surgical release of contractures. A surgeon may cut through tendons to relieve contractures (tendon release surgery). Some surgeries can help the child continue to walk.
- Spinal fusion for scoliosis. Scoliosis in a wheelchair-dependent child with MD can become so severe that it aggravates breathing problems. Having spine surgery before this happens can help with breathing function, lessen back pain, and improve sitting balance. All of these factors improve the child's quality of life. The doctor may recommend surgery when the spinal curve reaches a certain size (greater than 20°). A surgeon will perform a spinal fusion using metal rods to hold the back in a straighter position.
Like all children, those with MD need to feel loved, valued, and safe. They need to develop strong self-esteem. Parents, siblings, other family members, and friends can help by seeing the child first, not the disease.
Keep a positive attitude, communicate openly and honestly, and be patient and optimistic. By giving your love, support, and encouragement, you can help your child have a happy and rewarding life, despite the challenges of MD. Some tips for coping:
- Encourage your child to stay independent for as long as possible.
- Answer your child's questions about MD. Give an older child more information about the disease, and allow him or her to take part in medical decision-making.
- Ask for and accept help from other people. Family members of people with MD face significant physical, emotional, and financial commitments.
- Don't blame yourself for your child's MD. At various times, everyone in the family may experience all the stages of grief--denial, anger, bargaining, depression and acceptance. As MD progresses, crisis points can trigger powerful emotions. Consider joining a support group to learn coping strategies and to know that you are not alone.
Reviewed by members of POSNA (Pediatric Orthopaedic Society of North America)
The American Academy of Orthopaedic Surgeons
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