Congenital muscular dystrophy (CMD)

Congenital muscular dystrophy (CMD) is the name for a group of conditions that are usually present from birth, or show up in the first few months of life.

The symptoms of congenital muscular dystrophy (CMD) are:

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

If contractures are severe, they can sometimes 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.

Some children with CMD don't have contractures. In them, the first symptom can be difficulty holding the head up. Or there might be delays in learning to sit unaided, stand or walk.

Congenital muscular dystrophy (CMD) is a genetic condition.

The mutation causes a loss of glycoproteins in the cells, and this affects how the muscles normally work. With this kind of mutation, the muscles are more likely to be injured even by normal use. They also become less able to repair any damage.

Doctors don't know why CMD causes muscle weakness earlier than other types of MD. One possibility is that the muscle proteins affected are needed earlier, while a child's muscles are still developing. The proteins linked to other muscular dystrophies might not be needed until they're used more as the child grows up.

Several tests can help doctors diagnose congenital muscular dystrophy (CMD).

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

An EMG tests the electrical activity in the muscles. A small needle is inserted into the muscle to record that activity, and the result might show an abnormal pattern. Children might have this procedure under general anaesthetic.

A muscle MRI might be used to show which muscles are involved. That pattern helps the doctor work out the type of CMD. Children might have this procedure under general anaesthetic too.

A muscle biopsy might be used to find out which specific type of congenital muscular dystrophy you have. Again, children might have the procedure under general anaesthetic.

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

There is no cure for congenital muscular dystrophy (CMD), but supportive treatments can help manage your symptoms or your child's.

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

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

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

Feeding can be difficult for your child. A nasogastric tube or a gastrostomy tube may be put in to help with feeding.

Breathing problems are likely, and your child will probably need 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 clear secretions (phlegm). Using an Ambu bag can help preserve the strength of their chest wall muscles.

Children with CMD are at risk of frequent chest infections. These might be treated with antibiotics.

Bladder problems are common in people with muscle disorders like muscular dystrophy.

You might have urinary incontinence, where you pee by accident. Weak pelvic floor muscles, together with weak core muscles, are often the cause.

You're more likely to have urinary incontinence if you:

• have poor mobility
• spend a lot of time sitting down

Pelvic floor exercise may help. Medicine can sometimes help with an urgent need to pee.

You might also have bowel problems like:

• chronic constipation
• diarrhoea with little warning
• bowel incontinence

Some people drink less water than is recommended so they don't have to go to the toilet during the day. This could cause dehydration, which can make constipation worse and add to bowel problems.

Using a gentle laxative like Lactulose regularly during the week may help. Medicine can sometimes help too.

Surgery might be used to correct scoliosis and to stop it getting worse.

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

Many children with CMD take part in school activities without being held back by their condition. Others may need extra support to get the most out of their time at school.

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

• counselling
• pain management