What is Muscular Dystrophy and What are the Types?

Muscular dystrophy is a group of conditions that cause progressive muscle weakness and loss of muscle mass. In muscular dystrophy, abnormal genes (mutations) interfere with the production of proteins needed to form healthy muscle. The most common type of muscular dystrophy, Duchenne muscular dystrophy (DMD), occurs mostly in boys. Symptoms usually appear between ages 2 and 5, with progression happening over 2-3 decades. The number of Duchenne muscular dystrophy cases has been steadily growing, particularly in more developed countries such as the United States, where awareness and access to care have improved dramatically during the last 50 years.

Muscular dystrophy is a serious genetic disorder that causes progressive muscle weakness. There are many kinds of muscular dystrophy, and symptoms vary depending on the type. The most common form of muscular dystrophy begins in childhood, mostly in boys. Other types do not surface until adulthood.

Muscular dystrophy (MD) is a disease that affects the muscles. There is no cure for MD, but medications and therapy can help manage symptoms and slow the course of this disease.

Symptoms

People with muscular dystrophy experience progressive muscle weakness that begins at different ages, depending on the type of muscular dystrophy. For example, symptoms of Duchenne muscular dystrophy usually first appear in early childhood and may include weakness in the legs and hips, abnormal posture and gait, trouble running and jumping, learning problems, irregular heartbeats, and diabetes mellitus.

Duchenne type muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common type of muscular dystrophy. It is found more often in boys than in girls and its cause is unknown.

As a parent, you may want to monitor your child’s development and growth from birth. In early childhood, signs and symptoms that might indicate a problem include

• Frequent falls and trouble getting up from lying or sitting positions. Other warning signs include trouble running and jumping, or being clumsy during these activities.
• Your child will continue to grow for most of their first 12 years. At about two years old, they will begin to walk, but at first, they might walk on their toes or have a waddling gait. You might notice large calf muscles which help them walk. Around the age of three or four, they will start walking more naturally and using their arms to balance.
• The signs of vitamin D deficiency are often subtle. A lack of this essential nutrient can contribute to muscle pain and stiffness, cognitive impairment, and learning disabilities. Children with low levels of vitamin D may suffer from delayed growth and delayed puberty.

Becker muscular dystrophy

Becker muscular dystrophy (BMD) is an inherited neuromuscular disease that causes progressive muscle weakness, disability, and loss of movement. Its signs and symptoms are like those of Duchenne muscular dystrophy but tend to be milder and progress more slowly.

At first, the symptoms are subtle, but then the muscles weaken and become very weak and rigid until eventually, it can lead to heart failure. Becker muscular dystrophy, on the other hand, is a milder form where people tend to have less severe symptoms and usually do not lose their ability to walk until much later in life.

Other types of muscular dystrophy

There are several types of muscular dystrophy. Some are defined by a specific feature or by where in the body symptoms begin, this includes-

• Myotonic is the most common type of muscular dystrophy. It causes muscle weakness and difficulty relaxing certain muscles after they have been used. The most common symptom is a tendency to drop your jaw, although people with this condition may have other signs such as drooping eyelids or a swanlike neck.
• Facioscapulohumeral muscular dystrophy (FSHD) is a genetic disorder in which muscles become progressively weaker over time. Symptoms can include muscle weakness in the face, hip, shoulder, and upper arm. Muscle weakness typically begins in the face, hip, and shoulders. When arms are raised, shoulder blades may stick out like wings. Onset typically occurs in the teenage years but can begin in childhood or as late as age 50.
• Childhood-onset forms, which begin in the first few years of life, affect both boys and girls. Many of these types show a tendency to slowly progress, but some become so severe that they may be apparent at birth or within a few months afterward. These types include Rett syndrome (Rett’s), fragile X syndrome, and Nance-Horan syndrome. Infantile autism is considered a childhood-onset form of autism spectrum disorder. With most childhood-onset forms, signs and symptoms progress rapidly during the first 2 years, continue to worsen for several years, then level off.
• Limb-girdle, People with this type of muscular dystrophy may experience their first symptoms in childhood or young adulthood. They might have difficulty lifting the front part of their foot, so they might trip frequently. Their hip and shoulder muscles are usually affected first. Onset is frequently before age 20, or sometimes younger than 10 years old.

When do you need to consult with the doctor?

Because muscle weakness can be caused by many different conditions and may occur along with other symptoms, it is important to see a doctor if you notice signs of muscle weakness such as increased clumsiness, falls or difficulty moving the arms, legs, or trunk in you or your child.

Causes

Muscular dystrophy is a genetic disease. A defective gene causes muscle fibers to degenerate, leading to myopathy, or muscle weakness. Patients usually become wheelchair-bound by mid-adulthood and must have mechanical ventilation and feeding tubes to survive.

Each form of muscular dystrophy is caused by a genetic mutation particular to that type of disease. Most of these mutations are inherited, not acquired. They do not spread through the air or by touching an affected person, in most cases, it takes two parents to pass along the mutation to a child.

Risk factors

Muscular dystrophy is a common and serious disease that can affect people of all ages. It can occur at any time in life and it affects all races, but most commonly occurs in young boys. Genetic factors are involved in about half of all cases, but not enough is known about the inheritance pattern to provide a meaningful explanation. There are more than 30 different types of muscular dystrophy, and although some involve only weakness, others cause muscle wasting and an increase in body fat. Loss of muscle control occurs in some types of muscular dystrophy and leads to death from other causes such as pneumonia or choking.

Complications

Progressive muscle weakness is one of the most common complications of ALS, which can affect every muscle in your body. Some symptoms of progressive muscle weakness include:

• Most people with muscular dystrophy can walk for a long time, and many do not need a wheelchair until late in the disease. But eventually, muscular dystrophy can lead to trouble walking some people need a wheelchair from the start. As it gets harder to walk, you may have trouble climbing stairs, standing for long periods of time, and sitting in soft chairs like sofas and recliners.
• For many people, even simple tasks such as reaching for a glass of water or hanging out the clothes can become more difficult if their muscles are affected by MS. One way to address this is by strengthening muscles, something you can do on your own home with this stretch band.
• In some cases, muscles or tendons around the joints will shorten from lack of movement, causing them to pull on the bones of a joint. This can lead to contractures that further limit mobility.
• Progressive weakness and muscle wasting can seriously affect the lungs and breathing. Progressive muscular dystrophy can eventually lead to the need for a breathing assistance device (ventilator), which will be initially used at night but may also need to be used during the day.
• If you have scoliosis, weakened muscles might be unable to hold your spine straight. When the spine curves into an S shape (see the figure), it can lead to breathing problems and make it hard for you to stand up straight.
• Muscular dystrophy can reduce the efficiency of the heart muscle. The disease can cause faint, irregular heartbeat, and fluid build-up in the lungs. For some people with this condition, it may also lead to death.
• Swallowing problems may develop from cancer or from the treatment itself. Your doctor needs to examine you and suggest ways to avoid or minimize these problems. If the muscles involved with swallowing are affected, nutritional problems and aspiration pneumonia can develop. Feeding tubes might be an option.