Muscular dystrophy

Muscular dystrophy is a group of diseases that causes muscles to become weaker and lose mass over time. The condition is caused by changes in the genes that make proteins needed to form healthy muscles.

There are many types of muscular dystrophy. Symptoms of the most common type start in childhood, mostly in boys. Other types sometimes don't start until adulthood.

Medicines and other treatments can help manage the symptoms and slow the course of muscular dystrophy.

The main symptom of muscular dystrophy is muscle weakness that becomes worse over time. This makes everyday tasks harder to do. The type of muscular dystrophy that a person has determines the:

• Exact symptoms.
• Age range at which the symptoms start.
• Muscle groups that are affected.

There are over 30 types of muscular dystrophy. Here are some of the main types along with key symptoms.

Duchenne type muscular dystrophy

This is the most common form. Girls can carry the gene change that causes the disease, and some have symptoms. But this type of muscular dystrophy is much more common in boys.

Most often, the symptoms of Duchenne muscular dystrophy start in early childhood. The symptoms can include challenges with movement, such as:

• Late walking.
• Frequent falls.
• Trouble rising from the floor or a lying or seated position.
• Trouble running, jumping or climbing stairs.
• Waddling gait.
• Walking on the toes or the balls of the feet.

Other symptoms can include:

• Large calf muscles.
• Muscle pain and stiffness.
• Learning or behavior-related challenges.
• Delayed growth.

Becker muscular dystrophy

The symptoms of this type are like those of Duchenne muscular dystrophy, but Becker muscular dystrophy tends to be milder, and it becomes worse more slowly. In general, symptoms start in the teens or early adulthood. They might not occur until the mid-20s or later.

Other types of muscular dystrophy

Some types of muscular dystrophy are defined by a certain feature. Or they're defined by where in the body the symptoms start. Examples include:

• Emery-Dreifuss. The symptoms of this type often start by age 10. Emery-Dreifuss muscular dystrophy causes certain joints to become stiff. Early on, some children may walk on their toes due to stiff tendons in the heels. They also may have trouble bending the elbows. This type of muscular dystrophy also causes muscles in the shoulders, upper arms and calves to slowly waste and weaken. Some people with the disease develop heart conditions that can cause fainting. Heart conditions need to be watched closely by a healthcare team.
• Myotonic. With this type of muscular dystrophy, the muscles can't relax at will. For example, it might be hard to let go of someone's hand after shaking it. Facial and neck muscles often are the first to be affected. Symptoms often start between the ages of 20 and 30, but some have symptoms shortly after birth to childhood. As the disease becomes worse, the heart might beat out of rhythm and the heart muscle can grow weaker. Heart rhythm issues can be the first complication for some people. Muscles involved in breathing also can become weaker. This can lead to poor breathing, especially during sleep. Other names for myotonic dystrophy are Steinert's disease or dystrophia myotonica.
• Facioscapulohumeral (FSHD). With this type, muscle weakness usually starts in the face, shoulders and upper arms. The weakness often affects one side of the body more than the other. When muscles around the eyes are affected, that can cause trouble fully closing the eyelids and lead to dryness of the eye. When the shoulders are affected, the shoulder blades might stick out like wings when the arms are raised. Sometimes, mild hearing loss also may occur. The symptoms of FSHD tend to start in the teenage years.
• Congenital. There are many types of congenital MD. These types cause symptoms at birth or before age 2. Most children with congenital muscular dystrophy have muscle weakness that becomes worse. But some forms of congenital muscular dystrophy progress slowly and cause mild disability. Others become worse quickly and cause serious health challenges. Babies with muscle weakness or lack of muscle tone can seem "floppy." Later on, babies and toddlers might take longer than usual to roll over, sit up or walk. Or they might not meet certain milestones of development at all.
• Limb-girdle. This type often affects muscles around the shoulders and hips. Some people with limb-girdle dystrophy develop minor disabilities over time. Others develop serious trouble using their arms or legs to do everyday activities, such as walking or carrying things. The age at which symptoms start, how serious they become and how quickly they get worse varies.
• Oculopharyngeal. This type tends to weaken the eyelids and the throat muscles. It's also been linked with muscle weakness in the limbs and near the center of the body from top to bottom. It can cause trouble swallowing, weakness of the tongue and drooping eyelids. In time, some people also have trouble with movement. Symptoms often start in the 40s and 50s, and they become worse slowly.

Get medical advice if you notice symptoms of muscle weakness in yourself or your child. Symptoms could include delays in development, more clumsiness than usual and falling.

Certain genes are involved in making proteins that protect muscle fibers. Most muscular dystrophy happens when one of these genes goes through an irregular change. You might hear this called a gene mutation.

Each type of muscular dystrophy is caused by a gene change that is particular to that type of the disease. Most of these gene changes are passed from parent to child, also called inherited.

Muscular dystrophy occurs in people of all ages and ethnic groups. But the most common type, Duchenne, usually affects young boys. People with a family history of muscular dystrophy have a higher risk of getting the disease or passing it on to their children.

Muscular dystrophy can lead to serious health issues, such as the following:

• Trouble walking. In time, some people with muscular dystrophy will use a wheelchair for mobility.
• Trouble using arms. Daily activities can become harder if the muscles of the arms and shoulders are affected.
• Shortening of muscles or tendons around joints, called contractures. Along with the weakness caused by the muscular dystrophy, less range of motion in joints also can limit walking and arm use.
• Trouble breathing or coughing. Over time, muscular dystrophy can affect the muscles involved in breathing. Some people who develop serious trouble breathing might need to use devices that help keep the airways open or assist with breathing. Muscular dystrophy also can affect muscles that are used to cough. That can make it hard for the body to remove mucus from the lungs and windpipe. If your child has trouble coughing, ask your healthcare professional to recommend techniques or treatments that can help.
• Curved spine, also called scoliosis. This is most likely to happen in a growing child who can't walk. The curving may play a role in breathing troubles and challenges with getting into certain positions. Sometimes, surgery is needed to correct the curving.
• Heart problems. Muscular dystrophy can make it harder for the heart to pump well or beat with a regular rhythm.
• Swallowing problems. If the muscles involved with swallowing are affected, that can lead to trouble getting enough nutrition. Trouble swallowing also raises the risk of a lung infection caused by breathing food or liquid into the airways. This is called aspiration pneumonia. To lower these risks, nutrition may need to be given through a flexible device called a feeding tube.
• Brain-related differences. Some children with certain types of muscular dystrophy have challenges with learning, intelligence or social skills. For example, those with Duchenne muscular dystrophy may have higher rates of autism spectrum disorder, ADHD, obsessive compulsive disorder and anxiety compared with people who don't have muscular dystrophy. If your child has a learning, intellectual or mental health condition, talk with your child's school. Ask for changes that can help your child learn more easily, called accommodations.
• Weakening bones. Children may have fewer minerals in their bones than usual. This is called low bone density. It can lead to weaker bones over time, especially in children who use wheelchairs. Low bone density raises the risk of broken bones, also called fractures. A healthcare professional might prescribe medicines to help strengthen weak bones.