Page 38 - Handbook of Electronic Assistive Technology

Chapter 1 • Basic Neurosciences With Relevance to Electronic Assistive Technology 25

specifically related to muscle, and secondary, i.e., reactive to infective, inflammatory, met-
abolic or endocrine disorders, which lead to a secondary deterioration.
MUSCULAR DYSTROPHIES
This is a group of genetic disorders of muscle function leading to weakness and loss of
muscle – atrophy. They are generally X-linked, problems from abnormalities on the X
chromosome (mainly Xp21.2 position); boys are affected. The muscle fibres degenerate
because of lack of specific proteins vital for their function, in particular dystrophin.
The rate of progression and pattern of disorder depend on the type of dystrophy.

DUCHENNE’S MUSCULAR DYSTROPHY
This is the most severe form, with a prevalence of around 2–3/10,000 boys. Progressive
weakness presents in the first decade with difficulty in standing or going upstairs. Fat takes
the place of muscle, initially in the lower limb; core muscles and upper limb muscles then
become involved as the dystrophy progresses.
Until fairly recently, early death was caused by involvement in the respiratory mus-
cles, usually in late adolescence. There has been a considerable amount of neurogenetic
research in recent years trying to turn back the deterioration by creating new dystrophin
and this is a hugely important area of trials.
At present, electronic assistive technology plays an enormous role in supporting func-
tion and participation in this group of young adults.

BECKER’S MUSCULAR DYSTROPHY
This is a less common X-linked disorder and less severe with some dystrophin created in
muscle. Deterioration is slower with loss of walking for those in their 30s and death a few
decades later.
There are also a variety of non-X-linked/autosomal muscular dystrophies, which are
generally labelled by the muscle areas involved – it does what it says on the tin.
Examples include limb girdle and facioscapulohumeral dystrophies. Genetic abnor-
malities in these are usually dominant and are caused by problems in genetic areas on
nonsex chromosomes coding for other proteins important in muscle function.

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