Focus On Parkinson’s
by Dr John Rees
Parkinson’s Disease affects about two in a thousand people mostly over 65 and was first described by Dr James Parkinson, a London doctor 200 years ago. Dr Rees explains more.
Parkinson’s Disease (PD) is characterised by slowly reduced movement typically starting on one side of the body. This progresses to involve walking and speech and eventually all movements are limited. Associated with this is a stiffness of muscles, difficulty initiating movement, so called ‘freezing’, a tendency to walk with little steps, impaired balance and in about 30% of patients, the characteristic tremor when the limb is at rest.
PD is due to death of cells in a part of the brain called the substantia nigra that produce dopamine, an essential chemical messenger (neurotransmitter), that helps to coordinate normal muscle movement. Dopamine also acts as a neurotransmitter in other essential brain pathways and in many other parts of the body. The cause of this cell loss is unknown in most patients although a small proportion will have a background of brain trauma, encephalitis, drug or toxic exposure and in about 10% a family history.
The current treatment was a considerable triumph when introduced in the early 1970s. Up to that point there was no effective treatment. Once it was appreciated that dopamine was the missing substance and its chemistry understood, L Dopa was formulated and when taken by mouth transformed the slowness and stiffness of muscle movement. It was less effective against the tremor. It was a very exciting period, patients literally got up from their beds and walked.
Current treatment is based on L Dopa in various formulations, often in association with drugs that enhance its effect and also other synthetic drugs that act in the same way in the brain. Tablets taken twice or three times daily are highly effective in most patients, restoring function to good or very good for some time with relatively little in the way of side effects. Transdermal patches are useful in some patients.
In general, the benefits of treatment last about a decade and then problems begin to occur. These problems initially relate to a ‘wearing off ’ effect and later what seem to be a sensitivity to the drugs which appear as excessive involuntary muscle movements, called dyskinesias. The early problems can be dealt with by careful tailoring of the timing and dose of patient’s medication which is entirely individual. Later on, it may be necessary to consider giving the active drug continually via a subcutaneous line attached to a pump.
In a very few patients brain surgery is appropriate after careful selection. Electrodes can be directed very carefully into a small region of the brain called the subthalamic nuclei where small currents from an internal ‘pacemaker’ can markedly reduce the abnormal movements.
There are clinics and neurologists specialising in the treatment of PD throughout the country backed up by very experienced specialist nurses. The Parkinson’s Disease Society is absolutely critical both in improving care for patients and supporting exciting research.
World Parkinson’s Day is on Wednesday 11th April. For more information visit www.parkinsons.org.uk/get-involved/world-parkinsons-day