Muscular Dystrophy Symptoms, Causes, Types, Diagnosis, Treatment, Prevention

Muscular Dystrophy Symptoms, Causes, Types, Diagnosis, Treatment, Prevention

What is Muscular Dystrophy?

Muscular dystrophy refers to a group of genetic diseases characterized by progressive weakness and degeneration of the skeletal or voluntary muscles which control movement. The muscles of the heart and some other involuntary muscles are also affected in some forms of muscular dystrophy, and a few forms involve other organs as well. The major forms of Muscular Dystrophy include myotonic, Duchenne, Becker, limb-girdle, facioscapulohumeral, congenital, oculopharyngeal, distal and Emery-Dreifuss. Duchenne is the most common form of muscular dystrophy affecting children, and myotonic muscular dystrophy is the most common form affecting adults. Muscular dystrophy can affect people of all ages. Although some forms first become apparent in infancy or childhood, others may not appear until middle age or later.

Types of muscular dystrophy, including:

  • Duchenne muscular dystrophy
  • myotonic dystrophy
  • Becker's muscular dystrophy
  • facioscapulohumeral muscular dystrophy
  • the limb-girdle muscular dystrophies
  • Emery-Dreifuss muscular dystrophy
  • oculopharyngeal dystrophy
  • distal muscular dystrophy
  • mitochondrial myopathies

The different types are distinguished by factors such as the:

  • age at which symptoms usually start
  • pattern of muscle weakness
  • speed at which the disease progresses
  • involvement of other tissues besides muscle
  • pattern of inheritance
Muscular dystrophy is rare. For example, although Duchenne muscular dystrophy is one of the more common types, it occurs in only 1 out of every 50,000 people. The other types of muscular dystrophy are even rarer.

Causes of Muscular Dystrophy

All muscular dystrophies are inherited. Each type of muscular dystrophy is associated with a distinct genetic mutation. The nature of the gene mutation and which chromosome it is located on determine the characteristics of the muscular dystrophy and the way the disease is passed from one generation to the next.

The gene responsible for Duchenne and Becker's muscular dystrophies normally produces a protein called dystrophin, which helps muscle cells keep their normal shape and function. The faulty gene that causes muscular dystrophies either does not produce enough dystrophin or produces dystrophin that doesn't work properly. This gene is located on the X chromosome.

Women have two X chromosomes, but men have only one X chromosome (men also have a Y chromosome, which does not have a copy of the dystrophin gene). Girls don't usually get the disease because the healthy gene on one X chromosome can produce enough normal dystrophin to compensate for the defective gene on the other X chromosome. Boys who inherit the defective gene are not so lucky since they do not have another copy of the good gene and are not able to make enough dystrophin to keep their muscles healthy.

A woman who has the abnormal gene is called a carrier. Each of her children (boy or girl) has a 50% chance of getting the gene from her. If the child is a boy and inherits the defective gene, he will develop the muscle disease. If it is a girl, she will be a carrier who can then pass the gene on to her own children.

Any woman in an affected family can be tested before deciding to get pregnant to find out if she is a carrier. If she is not a carrier, she cannot pass the disease on to any of her children. A fetus can also be tested for the disease during pregnancy.

What are the symptoms of muscular dystrophy?

The main symptom of Muscular dystrophy is muscle weakness. This varies greatly between the different types of Muscular dystrophy.

Symptoms may start anywhere between birth and middle age, depending on which type of muscular dystrophy is involved. In young babies, the muscle weakness may be noticed as 'floppiness' of the baby. In older babies and young children, the weakness may show up as the child having a delay in 'motor milestones', meaning a delay in learning to hold up their head, sit up, crawl or walk. (But note that there are many other causes of delayed motor milestones apart from Muscular dystrophy.)

There are also differences as to which parts of the body are affected. Different types of Muscular dystrophy affect different muscle areas (known as muscle groups) of the body - see the picture below.

The muscle weakness itself may be mild, moderate or severe. The different types of Muscular dystrophy vary as to how quickly or slowly the weakness progresses.

Sometimes there may be symptoms other than muscle weakness. These are:

  • Muscle wasting - where the muscles become thin.
  • Muscle hypertrophy - where the muscles are bulkier than normal, even though they work less well.
  • Aches or pains in the muscles.
  • Contractures - where joints are tight, due to tightness of the muscles or reduced movement of the joints.
  • Developmental delay in a child (this means that the child's 'milestones' of development are later than usual).
  • Some types of Muscular dystrophy can affect the heart. In some cases, there may be symptoms of heart disease without much in the way of muscle weakness.

How is muscular dystrophy diagnosed?

Usually it is first suspected because of symptoms: a muscle weakness is noticed by the patient, family or a doctor. Also, if a child has delayed motor milestones (as mentioned above), a doctor may advise testing for Muscular dystrophy, even though the problem could be due to another cause.

Muscular dystrophy may be diagnosed using one or more of the following tests:

  • A blood test for creatine kinase (CK) - in many types of Muscular dystrophy, the blood level of CK is very high.
  • A muscle biopsy - this involves taking a small sample of muscle under local anaesthetic. The sample is examined under the microscope and the muscle chemicals (proteins) may be tested.
  • Genetic analysis - this involves testing a person's DNA using a blood sample. It can detect many (not all) cases of Muscular dystrophy.
  • An electromyogram (EMG) - this is a recording of the electrical activity in a muscle.
  • Muscle ultrasound is used to look for suspected CMD.

How is muscular dystrophy treated?

There is no cure for Muscular dystrophy, although there are treatments which can help. The treatment offered will depend on what type of Muscular dystrophy you (or your child) have.

Firstly, you will usually be referred to a specialist, for tests and diagnosis. This may be a specialist in muscle and nerve conditions (a neurologist) and/or a doctor who specialises in genetic conditions (a geneticist). In some cases, the specialist may suggest that other family members be tested to see if they carry an Muscular dystrophy gene.

At present, the Muscular dystrophys cannot be cured. However, there are many types of treatment and aids that can help with the effects of the muscle weakness. The treatment needs to be fitted to the needs of each individual and the problems that they have from their Muscular dystrophy. As a general guide, treatment may involve:

  • Physiotherapy - to help keep the joints mobile.
  • For some types of Muscular dystrophy such as Duchenne type and LGMD, treatment with steroid medication can help to maintain muscle strength.
  • Practical aids or help may be needed; for example, a splint, wheelchair or equipment for the home.
  • For some types of Muscular dystrophy, regular check-ups are needed to assess and treat any complications.
  • Treatment of any specific problems, such as joint stiffness (contractures), heart or breathing problems.
There is a lot of research into Muscular dystrophy at present, and new treatments may be available in the future.

How to Prevent Muscular Dystrophy

Muscular dystrophy is an inherited disease. Get genetic counseling if you are concerned about having a child with muscular dystrophy, especially if you:

  • Have muscular dystrophy or a family history of the disease
  • May be a carrier of the gene for muscular dystrophy
  • Have a partner with a family history of the disease

What's It Like for Teens With Muscular Dystrophy?

Teens have different experiences depending on the type of Muscular dystrophy. One person might have weakened shoulder muscles and not be able to raise a hand in class. Someone might be unable to smile because of weak facial muscles. Another person might have weak muscles in the pelvis or legs, making it hard to walk from class to class. In some cases, you might not even be able to tell that a teen has Muscular dystrophy.

For teens with Muscular dystrophy, it can be hard to come to terms with the disease, especially because it gradually gets worse. For example, when someone who walks to class must start using a wheelchair in school, it can be a difficult adjustment. Support from doctors, family, and friends can make it easier to deal with Muscular dystrophy. Changes like wider doorways at home and school can make it easier for teens with Muscular dystrophy to do many of the things they enjoy.

If you know someone who has Muscular dystrophy, there's a lot you can do to offer help and support. For example, some people with Muscular dystrophy may need help getting books out during class or rides to and from events.

Often, people with illnesses that gradually get worse over time can start to feel cut off from friends, especially as their friends may be going out and doing more things while they feel like they're becoming more housebound. Try planning activities that include a friend, brother, or sister with Muscular dystrophy, such as playing video games or watching movies at his or her home. Your friend or sibling will always be the same person — just more limited in movement.