Congenital muscular dystrophy (CMD)

The congenital muscular dystrophies (CMD) are a group of conditions normally present from birth, or in the first few months of life.

Symptoms of congenital muscular dystrophy

The symptoms of CMD are:

  • low muscle tone or floppiness (hypotonia)
  • tightness (contractures) of the ankles, hips, knees and elbows
  • respiratory (breathing) problems because of weakness of breathing muscles
  • eye problems
  • learning difficulties

Sometimes if contractures are severe, they can affect several joints. This is known as arthrogryposis. Contractures develop because the baby has not had the muscle strength to move around in the womb.

If children do not have contractures, sometimes the first symptom is difficulty holding their head up. Or, there might be delays in learning how to sit unaided, stand or walk.

Causes of congenital muscular dystrophy

CMD is a genetic condition.

The loss of glycoproteins in cells due to the mutation affects the normal function of muscles. This type of mutation causes an increased chance of the muscles becoming injured from normal use. It also reduces the muscles’ ability to repair any damage.

It’s not known why CMD causes muscle weakness earlier than other types of MD. It’s possible that the muscle proteins affected are needed earlier during development of a child’s muscles. Other muscle proteins linked to other muscular dystrophies might not be needed until they’re used more as the child grows up.

Diagnosis of congenital muscular dystrophy

There are tests that can help to diagnose CMD.

Blood test

A blood test will measure the level of a muscle protein called creatine kinase (CK). In about 40% of congenital muscular dystrophy cases, the level of CK is 5 to 20 times higher than normal.

Electromyography (EMG) test

An EMG is used to test the electrical activity in muscles. A small needle is inserted into the muscle to record the electrical activity. This might show a pattern of abnormal activity in the muscle.

Children might have the procedure under general anaesthetic.

Muscle MRI

A muscle MRI might be used to show the pattern of muscles involved which will help diagnose the type of CMD.

Children might have the procedure under general anaesthetic.

Muscle biopsy

A muscle biopsy might be used to identify which specific type of congenital muscular dystrophy you have.

Children might have the procedure under general anaesthetic.

Genetic test

You might have a blood test which can be used for genetic testing. This might help identify the type of CMD you or your child has.

Treatment for congenital muscular dystrophy

There is no cure for CMD but there are supportive treatments available to help manage you or your child’s symptoms.

Mobility problems

Some children with CMD will walk. For others, it can be delayed and they may not walk until they’re 5 years old or later. In some children who do walk, they may become unable to walk as they grow older and heavier. This is because the muscles might become unable to cope with the strain as the child gets older.

Your child might be referred to a specialist for:

  • physiotherapy to work on muscle strength and flexibility
  • physical aids like a walking stick, crutches or a wheelchair
  • occupational therapy to help maintain independence
  • leg splints to help your child walk
Heart problems

Your child will have regular electrocardiograms (ECGs) to examine the heart rhythm. They’ll also need to have an echocardiogram.

Swallowing problems

Your child might have difficulty feeding. They might have a nasogastric tube or gastrostomy tube inserted to help with feeding.

Breathing problems

It’s likely your child will have breathing problems and will require a machine to help them breathe at night and sometimes during the day.

With older children, cough assist machines can help them cough up and remove secretions (phlegm). Using an Ambu bag can help to preserve their chest wall muscle strength.

There’s a risk of frequent chest infections in children with CMD. These might be treated with antibiotics.

Surgery

Surgery might be used to correct and to prevent scoliosis from getting worse.

Tight joints caused by tendon contractures can be loosened by surgically lengthening or releasing the tendons. This should improve movement.

Education support

Many children with CMD take part in their school’s activities unaffected by their condition. Others may need extra support to get the most out of their time at school.

Palliative care

You might want to consider hospice care to help you or your child cope with their condition. The hospice can offer help like:

  • counselling
  • pain management

Read more about palliative care

Read more about congenital muscular dystrophy


Last updated:
12 April 2023

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