Myotonic dystrophy
Myotonic dystrophy
Myotonic dystrophy is a genetic condition that causes muscle weakness and wasting that gets worse over time.
It can affect the muscles used for movement, and it often reaches the heart's electrical conduction system, the muscles involved in breathing and swallowing, the bowels, the lens of the eye and the brain. Diabetes and hormonal changes such as thyroid problems can also develop, and the reproductive system may be affected in both males and females. Some people go on to experience personality and behavioural changes.
In rare cases, it can raise the chance of developing tumours.
Common Symptoms
⚠️ This symptom list is for educational purposes. Having these symptoms does not mean you have this condition. See a doctor for proper diagnosis.
Medicines Commonly Used
⚠️ These medicines are commonly used for confirmed diagnoses of this condition. This is NOT a recommendation or prescription. Treatment must be determined by your doctor.
No medicines have been linked to this condition yet.
Causes
Myotonic dystrophy is a dominant inherited MD. It's normally passed on from one of your parents.
If you have a dominant inherited MD, you only need to inherit the altered gene from one parent to be affected.
This means, if you have a child with an unaffected partner, there's still a 1 in 2 chance your child will develop the condition. Very few cases of myotonic dystrophy occur with no family history of the condition.
A gene mutation (change) within the DMPK gene on chromosome 19 causes myotonic dystrophy type 1. Myotonic dystrophy type 2 is caused by a gene change in a different gene called the CNBP gene, which is found on chromosome 3.
A blood test will usually confirm a diagnosis of myotonic dystrophy.
Some parents or grandparents might have carried a very slight genetic change that never caused any symptoms or that was never diagnosed. Normally, careful and thorough study of the whole family will often show more members with the condition.
Treatment
Although there is no cure for myotonic dystrophy, a number of supportive treatments can help manage your symptoms.
If you have myotonic dystrophy, you will develop heart problems. Because of this, you should have regular electrocardiograms (ECGs) to check your heart rhythm, along with an echocardiogram.
You will also see a cardiologist (a heart specialist) for further tests and ongoing monitoring. The cardiologist can prescribe medication to help improve how your heart functions, and in some cases you may need a pacemaker or an ICD (implantable cardioverter defibrillator) fitted to support your heart. This is placed under the skin of your chest.
Your doctor may also consider medicines such as mexiletine to help with muscle stiffness.
If your dysphagia (difficulty swallowing) is mild, diet changes and speech therapy can often help. If it is causing significant weight loss, a dietician may suggest food supplements.
If your dysphagia is severe, there is a risk of aspiration pneumonia. This can be prevented by switching to a different method of feeding. In such cases, you may need a gastrostomy, a minor operation where a tube is passed through the front of your abdomen (tummy) directly into your stomach. This may be done as a PEG (percutaneous gastrostomy) or a RIG (radiographically inserted gastrostomy).
A gastrostomy helps ensure you get enough nutrition and hydration, lowers the risk of aspiration pneumonia, and still allows you to swallow small amounts of food or drink if you are able to. A PEG or RIG tube can easily be hidden under your clothing.
You will see an endocrinologist to manage diabetes or other hormonal issues, and possibly a respiratory specialist to check the strength of your breathing muscles and how well your lungs are working.
If your chest muscles weaken, you may need a machine to help with your breathing, particularly while sleeping. This can also help ease any daytime fatigue or sleepiness you may be feeling.
Some people experience diarrhoea, constipation or incontinence. If this happens to you, you may be referred to a gastroenterologist.
Exercise has been shown to help people living with myotonic dystrophy. You might be referred to a specialist for:
- physiotherapy, to help build muscle strength and flexibility
- physical aids, such as a walking stick, crutches or a wheelchair
- occupational therapy, to help you maintain your independence
You may also want to consider hospice care, to help you or your child cope with the condition. Hospice services can offer support such as:
- counselling
- pain management
- respite care
Read more about palliative care.
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