Page 32 - Handbook of Electronic Assistive Technology

Chapter 1 • Basic Neurosciences With Relevance to Electronic Assistive Technology 19

Direct problems dependent on the site, including epilepsy, and indirect problems from
raised intracranial pressure are often presenting symptoms.
Treatment is neurosurgery, radiotherapy and/or chemotherapy, as well as emergency
management to reduce intracranial pressure. Considerable rehabilitation and the involve-
ment of the MDT are often vital in minimising morbidity and improving prognosis.

Neurometabolic Conditions/Inherited Metabolic Disorders
Various disorders result from genetically determined abnormalities of different enzymes
normally found within nerves and their supporting cells.
This can affect cellular metabolism and consequently the development, function and
viability of the nervous system.
The range of enzymatic disturbances is considerable, leading to a variety of clinical
syndromes such as inborn errors of metabolism. Problems arise from too little of a prod-
uct, too little energy being formed, too much of a substrate, abnormal product used for
energy or structure building up in the cell. These problems lead either to accumulation of
toxic substances or to lack of components essential for normal functioning.
The most common inherited metabolic disorders are bracketed into abnormalities of
amino acid, carbohydrate, organic acid metabolism and lysosomal storage diseases
(build-up of toxins within subcellular organelles).
Lesch–Nyhan syndrome is a disorder concerning a normal building block of proteins –
purine metabolism that results in a build-up in the body of a waste product, uric acid, that
is normally excreted via the kidneys. Toxic levels of this have marked consequences in a
number of organs, not least the brain leading to disorders of neurotransmission, particu-
larly in the basal ganglia. An early, rapidly progressive movement disorder is characterised
by severe and intractable dystonia, lip and finger biting, together with moderate learning
difficulties, attention deficit and compulsive behaviours.
Kidney stones, pain and eventually renal failure are part of the progressive picture of
the condition.
Management of the child and young person is palliative, using diet and medicines to
reduce uric acid production and minimise the symptoms. Multidisciplinary management can
be extremely challenging, as the movement disorder and behavioural spectrum are so severe.
Lipidoses are a group of conditions where fats or lipids are not metabolised and
accumulate in cells causing progressive cell and tissue damage. They show recessive or
X-linked inheritance. Rate of progression is variable, some with early onset and rapid
death and others with slower progressive motor and learning disability, visual problems
and epilepsy. Examples include GM1 and 2 gangliosidoses and Tay–Sachs, Niemann–Pick,
Batten’s (neuronal ceroid lipofuscinosis) and Gaucher’s diseases.
Leukodystrophies are a group of conditions with a deteriorating clinical profile sec-
ondary to abnormal development or destruction of the myelin sheath in the white matter.
The rate of progression once again varies, with a clinical picture of loss of mobility, hear-
ing, balance, swallowing and memory. Examples include metachromatic leukodystrophy,
X-linked adrenoleukodystrophy and Aicardi–Goutieres syndrome.