Page 34 - Handbook of Electronic Assistive Technology

Chapter 1 • Basic Neurosciences With Relevance to Electronic Assistive Technology 21

imbalance – less dopamine, more glutamate neurotransmission – which in turn leads to
the clinical signs of reduced movement (hypokinesia), rigidity and tremor associated with
Parkinsonism.
Apart from the direct motor effects, problems are also seen in:

• Autonomic function, particularly in sleep pattern, pain, loss of smell and increased
salivation.
• Thought processing and planning.
• Depression, apathy and impulsive behaviour.

Medicines can be helpful as they can directly affect electrical stimulation of the sub-
stantia nigra – deep brain stimulation. Stem cell therapy has been used for a while, with
an increasing evidence base. Multidisciplinary therapy input is important for physical and
psychological well-being.
HUNTINGTON’S DISEASE
• Prevalence in the United Kingdom – 12/100,000.
• Autosomal dominant, short arm chromosome 4. Selective neuronal loss occurs mainly
in the basal ganglia areas of the putamen and caudate nucleus.
• Symptoms generally appear around 30–50 years of age.
• Increased irregular and sudden movements are accompanied by low muscle tone.
Dementia and depression increase over the next 10–15 years followed by death.
Palliative care, with support to enable a degree of independence and function over that
period, is the focus of management.

PRIMARY DYSTONIA
• Damage in the basal ganglia, particularly the globus pallidus (remember the locomotor
driving system all those pages ago), leads to uncoordinated motor control, poor fluidity
of movement and frequently painful muscle spasms.
• Dystonia can be focal or generalised in nature, primary if not associated with another
neurological problem, and secondary to hypoxic/ischaemic damage or stroke.
• Primary dystonias are extremely rare and specific genetic changes (for example, in
the DYT-1 gene) lead to disrupted chemical signalling without macroscopic change.
Pantothene kinase-associated neurodegeneration leads to calcium deposition in the
globus pallidus causing dystonia, spasticity and rigidity.
• As with all basal ganglia problems, support from the full MDT is important to optimise
function and reduce discomfort.

PROGRESSIVE SUPRANUCLEAR PALSY
Progressive supranuclear palsy (PSP) affects approximately 4000 people in the United
Kingdom, mostly over the age of 60. It is caused by the accumulation of a protein called
tau, which is found normally in brains, but in PSP there is a noninherited, multigenetic
abnormality which leads to deficiency of its breakdown. Clumps of tau protein are formed
in neurons, particularly in the basal ganglia and brain stem, frontal cortex and cerebellum.