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Parkinson's
Disease
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What
is Parkinson's Disease?
Parkinson's Disease is a disease affecting
the part of the brain known as 'the basal ganglia' which controls aspects
of movement pertaining to maintenance of muscle tone balance, coordination
of opposing muscle groups, and the smooth transition from the resting
state to movement. These seemingly unrelated aspects of muscle control are
what enable a normal person to move in a fluid and gradual manner, without
unnecessary jerking motions as complex groups of muscles go into action.
In addition, it allows us to use certain muscle groups while allowing
others to stay relaxed.
In Parkinson's Disease, the basal ganglia
begins to degenerate progressively for unknown reasons. The functional
defect seems to include a deficiency of the chemical called dopamine in
this area, and other chemical disturbances are suspected as well. It has
been postulated that this damage may result from some unknown toxic
element or as the result of a previous viral infection. Familial factors
do not seem to play a major role. It is not a contagious disease, and
generally affects older people.
Any or all of the findings of Parkinsonism
may be caused by specific drugs (especially the major tranquilizers such
as Thorazine and Haldol), and following encephalitis or other forms of
brain injury. However, recent research has revealed that some nutritional
factors may be important.
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Symptoms
Although symptoms of Parkinson's disease can
occur in the fourth and fifth decade, over 85% of cases usually afflict
people in the late middle years or in old age, in a gradual manner. One
side of the body may be affected in the initial stages but both sides
generally become involved as time goes on. The patient may develop
difficulty in initiating walking or other movement, and such movements may
be very slow and deliberate. Resting muscle tone may increase, such that a
rigid appearance develops. This interferes with such spontaneous phenomena
as facial expression, and a so-called "mask-like" face is
common. The arms may fail to swing naturally during walking. A shuffling
gait with a tendency to turn the whole body instead of just the head may
occur.
The characteristic tremor (which is not
present in all patients) is the most obvious symptom, but often it is less
disabling than the above problems. It is usually in the resting state and
involves the hands in a 4 or 5 per second "pill rolling" motion
of the thumb and index finger. The head, lips, and other parts may be
involved. Interestingly, the tremor may briefly abate during other
purposeful motions.
Dementia, seborrhea of the skin, and
difficulty with wide blood pressure fluctuations are present in some
patients, and the endstage disease may involve all of the above symptoms,
leaving the patient a total invalid.
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Conventional
Treatment
The drug levodopa (l-dopa) has revolutionized
the treatment of Parkinson's Disease, although not without a price in
terms of side effects. It is often given with a second ingredient called
carbidopa which reduces some of the side-effects, the combination drug is
called Sinemet. Digestive upset and hemorrhage, cardiac rhythm
disturbances, confusion, depression, and even psychosis and delirium are
among its adverse effects in some patients, and often are dose-related.
Some patients develop, ironically, bizarre facial or other movement
disorders which may be quite grotesque.
Despite the potential side-effects,
l-dopa
can provide dramatic benefit for some patients who had been virtually
crippled by their disease but it is a poorly understood drug. Other
medications which are of less benefit and less toxic are sometimes used in
milder cases. These include bromocriptine, trihexyphenidyl and amantadine.
However, these drugs rarely provide significant long- term benefit.
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Prognosis
Parkinson's Disease is progressive, although
the rate of progression is variable from patient to patient. Even with
optimal conventional treatment, disability may still occur within 5 to 10
years, though current therapies may help significantly. Life expectancy is
affected by this disease, although the more optimistic recent estimates
suggests it remains within six months of normal life expectancy.
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