Muscular dystrophy, the facts / Alan E.H. Emery.

  • Alan Emery
Date:
[1994], ©1994
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Muscular dystrophy, the facts / Alan E.H. Emery. Source: Wellcome Collection.

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    24 Different types of muscular dystrophy Duchenne muscular dystrophy is due to a mutation on the X chromo¬ some and is therefore inherited as a so-called X-linked trait. This will be discussed further in Chapter 8. It means, however, that only boys are usually affected. The onset is often ill-defined. Looking back over the child's history there may have been some delay in learning to walk. In one survey of affected boys about half had not been walking by the age of 18 months, whereas almost all normal children are walking by this age. Sometimes the first thing parents notice is that the calf muscles are enlarged but usually medical attention is not sought until the parents begin to realize that something seems to be seriously wrong. They may become aware that their son falls over more than other children, or he is never able to run well, or cannot get up from the floor or climb stairs properly. It has been said that any little boy who shows signs of a problem with muscle development should have a CPK test to exclude the possibility of Duchenne muscular dystrophy. Sometimes the diagnosis of Duchenne muscular dystrophy is not made perhaps until school age. By then difficulty in walking is usually obvious. He often walks on his toes with his abdomen pushed forwards and with a waddling gait. These are early hallmarks of the disease and result from weakness of muscles of the pelvis which normally extend the hips in order to retain the upright position when standing. When these muscles are weak there is a tendency for the pelvis to tilt forward and in order to compensate for this the affected boy pushes his abdomen forward and his shoulders backward. This results in what is called lordosis as it resembles the gait of a peer of the realm. Rising from the floor unaided also becomes increasingly difficult which, like the waddling gait, is due to weakness of the muscles around the hips. This results in what is referred to as Gower's sign after the English physician who first described it. Whenever there is weakness of the hip muscles (which is not limited to Duchenne muscular dystrophy but can also occur in other dystrophies and diseases) when attempting to rise the person presses on his thighs and then climbs up them in order to extend the hips and straighten up {Figure 6). At the same time as weakness of the hip muscles becomes evident there is also weakness of the shoulder muscles so that the affected boy has increasing difficulty raising his arms. The hip and shoulder muscles are referred to as proximal muscles, as opposed to distal muscles of the
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