It is important to remember that Myotonic Dystrophy is a highly variable disease so it is difficult to predict how one individual will be affected. The range of symptoms and the severity of symptoms both vary enormously. Age at onset when the disease first appears ranges from birth to old age. Although the disease is highly variable it can be broadly grouped into three categories.
1.Minimal. Individuals develop symptoms late in life. Cataracts are often the only symptom or there may also be mild muscle involvement.
2.Classical or adult onset. This type of Myotonic Dystrophy begins in adult life and is characterised by progressive muscle stiffness and weakening. Many other systems can be involved in varying degrees.
3.Congenital Myotonic Dystrophy. This is the most severe from of the disease and is present from birth.
Normally when the disease is passed on to the next generation it becomes more severe and the age at onset decreases. This pattern is called anticipation and means that in one family the grandparent may have cataracts as the only symptom, the parent may have the adult onset form of the disease and the child could be severely affected with congenital Myotonic Dystrophy.
Important features involving other systems may be more troublesome than the muscle symptoms and can seriously affect health. Specialists in these other systems may be unfamiliar with Myotonic Dystrophy and may not diagnose it.
Muscle Weakness – Weakness is very variable and may range from mild to severe. It particularly involves the face and eyelids, jaw, neck, forearms and hands, lower legs and feet. It can affect speech and give lack of facial expression.
Myotonia – Myotonia is a difficulty in relaxing a muscle after it has bee contracted, for example it may be difficult to let go after gripping something.
Heart problems – Abnormal rhythm of the heart might require treatment. This can affect adults even those without other symptoms. Regular ECGs (heart tracings) of affected adults are advised to detect problems at an early stage.
Chest and Breathing problems – Chest infections may result from weakness of breathing muscles or form food entering the lungs as a result of choking. Inadequate breathing during the night may lead to disturbed sleep, snoring, difficulty waking, morning headaches and daytime sleepiness.
Tiredness – Tiredness is very common and can occur at any time of the day.
Digestive problems – These are common as the muscle throughout the digestive system may be affected. This may lead to: swallowing problems (which can also be a cause of food entering the lungs), pains in the bowels with constipation and diarrhea, soiling of underwear particularly when stressed or excited and occasionally enlargement of the large bowel. Gallstones which can cause painful spasms after eating fatty food can be a problem in Myotonic Dystrophy and great care needs to be taken with any surgical treatment.
Eye problems – Cataracts can cause blurring and dimming of vision. This may be the only problem caused by Myotonic Dystrophy especially in the first affected generation of a family. Droopy eyelids can cause a problem with reading and watching television. Affected individuals should have regular check ups at the optician and see a medical eye specialist if there is any concern.
Anaesthetics and surgery – Myotonic Dystrophy can cause problems with recovery after an operation when certain anaesthetic drugs are used. Make sure that the surgeon and anaesthetist are aware of the condition before an operation. They may wish to contact a specialist centre for advice. A medical alert card or document (supplied free of charge by the support group) should be carried at all times in your wallet or purse in case of an accident or emergency.
Other problems include – Male infertility, diabetes (ask to have your blood or urine sugar checked regularly), the muscle in the womb may be involved and lead to a long difficult labour so that obstetric help may be required and the brain may be affected causing thinking and learning difficulties especially when onset is in childhood.
Special Difficulties in affected children – Muscle involvement can be more severe, especially when Myotonic Dystrophy is present from birth. Sometimes affected babies may only live for a short time. Speech, educational and behavioural problems can occur.
Genetic Tests – Accurate genetic tests are possible for healthy individuals who are at risk of developing Myotonic Dystrophy in the future because they have an affected parent or grandparent and early in pregnancy where one parent is affected. Genetic counseling is advised if genetic testing is being considered.
Information supplied by Prof. Peter Harper CBE FRCP DM, Professor and Consultant in Medical Genetics, University of Wales College of Medicine, Cardiff.
Not all patients need to be followed by a specialist clinic but all should be given full information about the condition and its consequences, including genetic aspects, and should have a clear plan for when medical help is needed. Specialist advice should always be sought in relation to surgery and anaesthesia, pregnancy or serious illness. A wide range of disability aids exist. It is important that these are chosen with expert assistance.
At present there is no cure for Myotonic Dystrophy but this may change as a result of rapid progress in our understanding of how the disorder is caused – meanwhile all people with Myotonic Dystrophy can help themselves by knowing about their condition, recognising and avoiding hazards, and by informing doctors and other professionals.