Muscular dystrophy

Muscular dystrophy is not one disease but a group of inherited conditions in which a fault in a gene leaves the muscle fibre without a protein it needs, and the fibre gradually breaks down. Muscles lose strength and bulk year by year. The fault itself still cannot be corrected, but the course of the illness has changed a great deal: treatment started in good time, together with monitoring of the heart and the breathing, adds years and makes them considerably easier.

How the weakness shows itself

The muscles that give way first are usually those closest to the trunk: thighs, buttocks and shoulder girdle. Hence a set of signs that are easily mistaken for clumsiness or laziness.

• A child struggles to get up from the floor: they roll onto their front and climb up their own legs, pushing with the hands on knees and thighs.
• A rolling, waddling walk, the tummy pushed forward, walking on tiptoe, frequent falls.
• Difficulty climbing stairs, running, or getting out of a chair without pushing up with the arms.
• Difficulty raising the arms above the head, hanging out washing or reaching a shelf; the shoulder blades stand away from the back like wings.
• The calves look disproportionately large and firm: muscle tissue has partly been replaced by fat and fibrous tissue, and the strength has gone down, not up.
• In toddlers, walking late, floppiness and delay in motor development.

In the forms that begin in adulthood the picture is different: the foot drops and the toes catch on the floor, the eyelids do not close fully in sleep, the face loses expression, and the hand is slow to let go after a firm handshake. Muscles ache and cramp, joints stiffen, and the feet and elbows become fixed in a bent position.

Forms that behave differently

The type of dystrophy decides almost everything: the age it starts, how fast the weakness advances, which muscles are affected, and whether the heart and breathing are drawn in. A diagnosis of "muscular dystrophy" on its own is therefore not enough.

• Duchenne muscular dystrophy is the commonest in childhood. It appears in the first years of life, affects almost only boys and progresses quickly.
• Becker muscular dystrophy comes from a fault in the same gene but a milder one: it starts later and moves more slowly, though the heart can be badly affected.
• Myotonic dystrophy is the commonest in adults. Besides weakness and difficulty relaxing a muscle, it involves the heart, the eyes, the hormone system and sleep.
• The limb-girdle forms begin at widely varying ages and affect shoulders and hips; there are dozens of them and they can only be told apart genetically.
• The facioscapulohumeral form: the muscles of the face, shoulder blades and shoulders weaken, often unevenly on the two sides.
• The Emery-Dreifuss form causes stiff joints and dangerous heart rhythm disturbances early on, sometimes before any noticeable weakness.
• The congenital forms are apparent from the first months of life.

Where the altered gene comes from

Muscular dystrophy is a genetic condition: one of the genes responsible for the strength of the muscle fibre does not work properly. Different genes give different forms.

The gene may come from the parents, or it may be altered afresh, in which case the condition appears in the family for the first time and the family tree gives no clue. Duchenne and Becker are passed on through women: a carrier mother is usually well but passes the altered gene to her sons. Some carriers do eventually develop weakness and, more importantly, heart involvement, so they need cardiac follow-up of their own.

If someone in the family already has the diagnosis, it is worth seeing a geneticist. They will explain who should be tested and what the options are when planning a pregnancy: carrier testing before conception, testing of embryos during in vitro fertilisation, and testing during pregnancy. The decision always belongs to the family; the doctor's job is to give accurate information before it has to be made in a hurry.

How the diagnosis is confirmed

The diagnosis is made in two steps: first it is shown that muscle is breaking down, then the exact fault is named.

• A blood test for creatine kinase, the enzyme that leaks out of damaged muscle cells. In Duchenne dystrophy it is tens of times above normal even before a child begins visibly falling behind.
• Genetic testing. This is what makes the final diagnosis, names the form and determines whether a treatment aimed at one specific type of fault will suit the person.
• Electromyography and muscle biopsy are needed less often than they used to be: they are kept for when the genetic search has not given an answer.
• MRI of the muscles shows which groups have been replaced by fat and helps direct the search.

There is a trap worth knowing about. Routine blood tests in a child often show raised "liver" enzymes, and a hunt for liver disease begins. In fact those enzymes are present in muscle too, and in dystrophy they rise from there: if the liver looks normal on ultrasound, it is sensible to check the creatine kinase, a simple test that saves months. The reverse holds as well: a normal blood count, a spine X-ray or an orthopaedic assessment do not rule muscular dystrophy out, because it does not show up in them.

Heart and breathing matter more than legs

Weak legs are obvious, but the dangerous part happens quietly: the heart muscle weakens, and so do the muscles that make it possible to breathe in and to cough. This goes on for a long time without complaints, which is why monitoring is scheduled from the moment of diagnosis rather than when symptoms appear.

The heart: in most forms an electrocardiogram and a heart ultrasound are done regularly, and treatment begins at the first sign that the pump is weakening, without waiting for breathlessness and swelling. In myotonic dystrophy and the Emery-Dreifuss form the main threat is not a weak heart muscle but disturbances of rhythm and conduction, which can cause the heart to stop suddenly; these patients may need a pacemaker or a defibrillator.

Breathing: weakness of the breathing muscles shows itself at night first. The signs are a morning headache, waking unrefreshed, sleepiness during the day and a need to sleep propped up. The cough becomes feeble, and an ordinary cold turns into pneumonia. The volume of air breathed out is measured regularly, and if needed sleep is studied and overnight breathing support through a mask is set up.

The spine is also watched, since the curve increases once a person stops walking and gets in the way of breathing; so is weight, which rises on steroid treatment and falls when swallowing is weak; and so is bone strength.

When urgent help is needed

Call an ambulance (112 across much of Europe) if any of these appear:

• shortness of breath, rapid shallow breathing, blue lips, confusion along with the breathlessness;
• choking with no ability to cough it clear;
• a faint, palpitations with sudden weakness, chest pain;
• weakness that increases sharply over a few hours.

See a doctor the same day if there is a fever and a cough the person cannot clear, if the urine turns the colour of strong tea after exertion or injury, if leg swelling and breathlessness when lying flat increase suddenly, and also if vomiting goes on and fluids cannot be kept down.

There is a separate rule the whole family should remember: before any operation, dental work included, the doctor must know the diagnosis. In muscular dystrophy some anaesthetic drugs can cause severe breakdown of muscle and a dangerous rise in blood potassium, and weak breathing muscles make waking from an anaesthetic harder. An anaesthetist warned in advance will simply choose different drugs. It is worth carrying a summary letter or a medical alert bracelet stating the diagnosis.

What treatment offers today

The faulty gene cannot yet be restored, but treatment can slow the illness and prevent much of what it would otherwise cause.

• In Duchenne dystrophy steroids are used: they preserve strength and walking for longer and delay curvature of the spine. They come at a cost (weight gain, fragile bones, effects on growth and mood), so they need monitoring and preventive measures. They must never be stopped abruptly.
• For certain genetic variants there are medicines aimed at one specific type of fault. They suit a minority and only where the mutation has been precisely identified: another reason to see the genetic testing through.
• The heart is treated with the same drug groups as any heart failure, started early; for rhythm disturbances a pacemaker or defibrillator is fitted.
• Breathing support through a mask at night and later during the day as well; separately, techniques to help clear the chest are taught and a machine is used for it.
• Physiotherapy and stretching, ankle splints and night splints slow the development of fixed contractures. Exhausting strength training, by contrast, does harm.
• Surgery for a marked curve of the spine straightens the sitting posture and makes breathing easier.
• An annual flu vaccination and pneumococcal vaccination make sense for almost everyone: for someone with a weak cough a chest infection is more dangerous than it is for others.

Daily life

Much of the help is not medicine. An occupational therapist works out what can replace a lost movement: arm supports, adapted handles, hoists. A wheelchair offered at the right time is not a defeat but a way of saving energy for what the person actually wants to do, and of avoiding fractures from falls.

The home usually has to be altered: thresholds removed, doorways widened, grab rails fitted, the bathroom made usable. School arrangements — a lift, help with the bag, typing instead of writing, extra time — are set up in advance rather than after trouble starts; an adult should discuss working from home, breaks and access to the floor with their employer.

When chewing and swallowing become weak, the texture and calorie content of food are adjusted and sometimes tube feeding is used. Low mood and anxiety are common and treatable; in some forms, particularly myotonic dystrophy, there is difficulty concentrating and a fatigue that gets mistaken for laziness. The family doing the caring needs breaks too.

Online consultation

A remote appointment is useful at any stage. Before a diagnosis the doctor can explain what a raised creatine kinase or unexplained high liver enzymes in a child actually mean and which specialist to take them to. After a diagnosis, they can go through the clinic letter and the genetic result in plain words, check that all the due heart and breathing assessments are being done on time, and advise on what to do about a cold, how to prepare for an anaesthetic and how to arrange adjustments at school or work.

Have ready your clinic letters, test and scan results, a list of medicines with doses and a short account of what the person has stopped being able to do alone over the past year. An online consultation does not replace a face-to-face neurological examination or heart testing; difficulty breathing, a faint or palpitations need urgent care in person.

This material is for information only and does not replace medical advice.