Dystrophy is any condition in which a part of the body weakens or wastes away. In muscular dystrophy, the weakness is in the muscles. An inherited genetic mistake prevents the body from making a protein that helps build muscles and keep them strong. Only males can get certain types of muscular dystrophy because of how the disease is inherited.
Children who are born with muscular dystrophy usually develop normally for the first few years of life. They may suddenly show signs of clumsiness. These signs include:
- trouble walking
- difficulty raising the front of their foot (called foot drop)
Over time, children with muscular dystrophy can become weaker and weaker, losing the ability to sit, walk, and lift objects. Because the disease can also affect muscles in the heart and lungs, shortness of breasth and abnormal heart rhythms can occur.
There are several different types of muscular dystrophy. Muscle weakness is a hallmark of each type. But the symptoms can vary and start at different ages.
Some muscular dystrophies are mild. Others are more severe and cause life-threatening muscle weakness.
Duchenne Muscular Dystrophy
Duchenne muscular dystrophy is the most common and severe form of the disease. It usually starts when a child is between ages 2 and 5.
Symptoms of Duchenne muscular dystrophy include:
- Muscle weakness that begins in the hips, pelvis, and legs
- Difficulty standing
- Trouble learning to sit independently and walk
- Unsteady, waddling gait
- Walking on the toes or balls of the feet
- Clumsiness, falling often
- Trouble climbing stairs
- Difficulty rising from a lying or sitting position
- Larger-than-normal calves that are sometimes painful
- Trouble breathing
- Learning disabilities or behavioral problems
- Curvature of the spine (scoliosis). This can cause one hip to rise higher than the other.
- Breathing problems that may eventually require the use of a ventilator
By age 12, most children with Duchenne muscular dystrophy must use a wheelchair to get around. The disease also damages the heart and the muscles needed to breathe, which can be life threatening.
Becker Muscular Dystrophy
The symptoms of Becker muscular dystrophy are similar to those of Duchenne muscular dystrophy. But Becker muscular dystrophy starts later -- around the teen years. It also develops much more slowly.
The first signs of Becker muscular dystrophy may be trouble walking fast, running, and climbing stairs. Other symptoms may include:
- Muscle weakness that starts in the pelvis, shoulders, hips, and thighs
- Waddling gait
- Walking on the toes
- Larger-than-normal calves
- Muscle cramps when exercising
- Trouble lifting objects above waist height because of shoulder and arm weakness
- Heart and breathing problems (later in life)
Often children with Becker muscular dystrophy can walk. As they get older they may need to use a cane or wheelchair to get around.
The symptoms of myotonic dystrophy may be obvious from birth or they can develop later -- during the teenage or adult years.
Like other forms of muscular dystrophy, myotonic dystrophy leads to muscle weakness that gets worse over time, leading to an inability to intentionally relax muscle. It usually affects small muscles first, such as those in the:
Symptoms of myotonic dystrophy can start at any time in a person's life. The symptoms include:
- Weakness in the muscles of the face, arms, hands, and neck
- Muscle stiffness (myotonia) -- difficulty relaxing the muscles after they are tightened
- Shrinking of the muscles over time (muscle wasting)
- Cataracts -- clouding of the eye's lens
- Daytime sleepiness
- Learning and behavioral problems
- Heart problems, including irregular heartbeat (arrhythmia)
The type of myotonic dystrophy that begins at birth is more severe. Other forms get worse very slowly, and can take 50 or 60 years to progress.
Limb-Girdle Muscular Dystrophy
This form of muscular dystrophy is actually a group of related conditions. It usually starts in childhood or during the teenage years.
Often the muscles that become weak first are the big muscles of the:
The muscle weakness gets worse very slowly over time.
Other symptoms include:
- Loss of muscle in affected areas
- Back pain
- Trouble lifting objects
- Difficulty running
- Fast heartbeat (palpitations) or irregular heartbeat
How serious the effects are depends on the child. Some children have only mild muscle weakness. Others are so weak they need to use a wheelchair.
In its later stages, limb-girdle muscular dystrophy can cause serious heart problems.
Facioscapulohumeral Muscular Dystrophy
Usually this type of muscular dystrophy doesn't appear until the teenage years or later in life. It also gets worse very slowly. Some people may not realize they have it until they are already old.
- Muscle weakness in the face. This affects the person's ability to close the eyes and purse the lips (whistle).
- Muscle weakness in the shoulders, upper arms, upper back, and lower legs
- Difficulty raising the arms or lifting objects because of muscle weakness in the shoulders and back
One side of the body may be more severely affected than the other.
If your child has symptoms of any type of muscular dystrophy, see your pediatrician to see what further evaluation is needed.