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| General
Illness Information |
Medical
Term: |
Parkinson’s
disease
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Common
Name: |
None Specified |
| Description: |
Parkinson’s
disease (PD) is a chronic, progressive movement disorder which
affects 1% of the population over the age of 65 years. This is a
neurological disorder which becomes apparent as cells in a certain
part of the brain (the basal ganglia), are lost. The disease is characterized
by a tremor which is present at rest, increased muscle tone
(stiffness) and/or a slowness in initiating movements.
The disease
usually presents in people over the age of 50 years. In younger people
without a family
history of PD, symptoms like tremor are likely to be due to some
other cause.
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| Causes: |
Unknown. There is accelerated loss of dopaminergic
neurons in the part of the brain called substantia nigra--- in
normal people loss of neurons occurs at 0.5% as opposed to 1% in
patients with Parkinsonism.
By
definition, PD is a disease without a known cause. PD is thought to
result partly from a genetic predisposition to the disease and
partly from exposure to toxic substances in the environment (which
are as yet unknown). If
the constellation of symptoms is identical to PD, but a known
environmental cause exists (e.g. carbon monoxide poisoning, a
specific drug or medication, manganese exposure), then the disease
is called “parkinsonism”, but not Parkinson’s disease.
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| Prevention: |
At present,
there is no medication or practice which is used to prevent PD. Therefore, no medication is
given to otherwise healthy people to prevent the disease. However, studies are being
done on “neuroprotective treatments” which, if used early in the
course of the disease, may slow the progression of the disease.
The most
promising of these neuroprotective treatments are:
·
Selegiline
(Eldepryl) - Selegiline is
an “antioxidant” therapy which may prevent damage to the affected
part of the brain. At
present, its “protective value” is still a matter of debate, so
discuss it with your physician if you are interested in this
treatment.
·
D3-Agonists
(e.g. ropinirole; pramipexole)
- These
medications bind to specific (dopamine) receptors in the brain,
thereby “replacing” the chemical (dopamine) which is in short supply
in the brains of people with Parkinson’s disease. Pramipexole is the
only medication studied as a “protective drug” and it was not
demonstrated to have a significant protective effect, but this may
have been due to the relatively small number of people involved in
the study. More studies
are planned, with a larger number of subjects.
Critics suggest
that the above medications may treat the symptoms of the disease
without necessarily slowing disease progression. In either case, these
treatments are useful in early PD, because they can delay the need
for a medication called levodopa. Your doctor will want to
wait to prescribe levodopa until your symptoms are severe enough to
require medical intervention, since this medication has many
side-effects which increase with the duration of treatment.
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| Signs
& Symptoms |
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Resting
Tremor - A “coarse” tremor which is present at rest (i.e. when
one is still).
This may affect one side of the body more than the
other, and it often involves the arms more than the legs in
the early stages.
A “pill rolling tremor”, which is a special sort of
trembling of the thumb relative to the other fingers, is one
of the classic signs of PD. The tremor may cause
problems with tasks involving fine motor skills, such as
buttoning clothes or cutting up food.
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Akinesia/Bradykinesia
- A slowness in initiating movements. This may cause some
difficulty in arising from a chair, beginning to walk from a
standing position, and turning around to begin walking in
another direction.
A decreased arm swing while walking may occur. “En bloc” turns
(turning the whole body a few degrees at a time instead of
quick pivoting) are characteristic. The rate of blinking
(of the eyes) is also noted to be slow. |
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Rigidity -
An increase in muscle tone, or stiffness, may be noted. The phrase “cogwheel
rigidity” is often used to describe a characteristic type of
increase in muscle tone and jerkiness of movement which the
physician might find on physical examination.
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Postural
Instability and Gait Disturbances - This “postural
instability” usually occurs later in the disease process. It causes some
difficulty in righting oneself when balance is lost, and can
result in falls and injuries. It also causes a
disturbance of gait (walking pattern). This may involve foot
shuffling, or other special patterns of
walking. (Your physician may
call this a. “festinating gait” or “retropulsive gait”.)
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Masked
Facies - A loss of normal facial expression may be noted,
giving the appearance of a “mask”.
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Oily skin
and/or a Rash (Seborrheic Dermatitis)
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Depression
- occurs in about 20% of PD patients at some time during the
course of the disease.
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Side
effects of medication (especially levodopa/”L-dopa”) - include
involuntary movements (dyskinesias), increased muscle tone
(dystonias), freezing spells (inability to move, “frozen in
place”), “wearing off” or “on-off” motor fluctuations
(increased PD symptoms, often near the time when the last dose
of medication is wearing off), and hallucinations.
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| Risk
Factors |
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Age - Age is
the most consistent risk factor for Parkinson’s disease. The disease rarely
occurs in people under the age of about 55 years.
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Male
Gender - Men are
affected four times more often than women.
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Genetics
and Family History - No gene
has been consistently associated with PD, with the exception
of a particular, rare form of rapidly-progressive, early-onset
PD, which tends to appear in patients at around the age of 40
years. In these
cases a gene on chromosome 4 has been implicated. However, a family
history of PD is still a recognized risk factor for the
disease. People
with an immediate family member with PD are 2 to 3 times more
likely to develop PD than members of the general
population. |
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Environment
and Toxin Exposure - Rural
living, well water, pesticide exposure and various other
factors have been studied, and have been found to increase the
risk of acquiring PD.
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Smoking
decreases the risk of acquiring PD in later life, BUT it
substantially increases the risk of lung disease, heart
disease, and many other health problems which will shorten
lifespan and decrease the quality of life even more than
PD. It is NOT a
recommended preventive measure for PD.
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| Diagnosis & Treatment |
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Parkinson’s
disease is a diagnosis that is made by observation of the
symptoms and their progression over time. The typical symptoms
are: tremor, akinesia/bradykinesia, rigidity and/or postural
instability.
Often, the diagnosis of PD is presumed, and then
confirmed when 2 or more of the above symptoms are present and
other causes of parkinsonism have been ruled out.
The region
of the brain that is affected is very small, and so it is not
possible to see the changes on a CT scan or an MRI. There are no blood
tests to diagnose this disorder (but blood tests are usually
done to rule out other conditions).
If there
is any doubt about the diagnosis, some physicians will
recommend a trial of levodopa, a medication that should
relieve the symptoms of PD. If the medication
helps, then parkinsonism is diagnosed, and if no cause can be
found, Parkinson’s disease is the final diagnosis. If the medication does
not help, this is not parkinsonism (and therefore, not
PD).
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| General
Measures: |
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Physical, occupational and speech
therapy. |
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Physical limitations require adjustments in the
home e.g. special chairs, raised toilet seat, eating utensils
and dressing oneself. | |
| Medications: |
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Levodopa/Carbidopa
(Sinemet or Sinemet CR) - The part
of the brain which is affected in PD (the basal ganglia)
normally helps to control movement. The cells in this region
produce a chemical called dopamine (a neurotransmitter). As the cells become
damaged, they produce less of this chemical. One of the treatments
for PD is therefore a medication, levodopa/carbidopa (Sinemet
or Sinemet CR), which helps to replace the missing chemical in
the brain. Since levodopa has a number of side effects, its
use is delayed until it is absolutely necessary. (See Signs and Symptoms,
above, for a list of side effects associated with this
medication.) In
the meantime, conservative measures such as education/counselling,
physical therapy and nutritional counselling are
suggested. Your
physician may use other medications in the early stages of
disease as well.
These “early treatments” include:
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·
Selegiline (Eldepryl)
- This is
a MAO-B (enzyme) inhibitor. It prevents the
breakdown of the “missing chemical”, dopamine. Side effects may
preclude its use in elderly or confused patients. This medication may
help to slow the progression of the disease by protecting the
dying cells from sustaining further damage.
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Dopamine
receptor agonists or agents that increase dopamine
release
- These medications include the D3-agonists ropinirole
(Requip) and pramipexole, which bind special
dopamine receptors and “act like” dopamine, thereby serving
the same function as the missing chemical. Bromocriptine and
amantadine are
other agents which increase dopamine release by stimulating
the remaining cells in the affected part of the
brain to
produce more of the missing chemical. Side effects of these
medications include somnolence and, in a small number of
patients, hallucinations. You might be advised
to avoid driving until you know how these medications affect
your alertness.
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If all
else fails, and medical therapy does not work, then surgical methods may
be used. Such
techniques involve destroying areas of the brain that may
cause tremor (pallidotomy) or
prevent initiation of movement (thalamotomy), or
implanting special electrical stimulators into the brain to
perform the same function as the damaged basal ganglia. New therapies on the
horizon include fetal
nigral stem cell transplantation, whereby healthy cells
are transplanted into the brain to replace the damaged ones.
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| Activity: |
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It is best
to maintain a regular regimen of physical exercise. Bed rest is not
recommended. If
you have difficulty walking, then choose activities where you
are not likely to fall, but remember to stay as active as
possible! | |
| Diet: |
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No special
diet is recommended.
However, a balanced diet is recommended for general
overall health maintenance, and your physician may recommend
that you consult a dietitian to design a well-balanced diet
which will keep you as well as possible.
If your
symptoms are not responding well to medical therapy with
levodopa/carbidopa (Sinemet), your physician will recommend
that you eat low-protein meals or snacks around the time that
you take your medication. This will help to
increase your absorption of the medication. Since you need protein
to stay healthy, this might mean that you end up eating your
daily protein requirement in one meal (e.g. at
dinnertime). This
type of diet requires a lot of planning, and you will be
referred to a dietitian to ensure that you will still be
eating a balanced diet while following your doctor’s
recommendation.
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| Possible
Complications : |
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Postural
Instability and Falls - In the
late stages of disease, postural instability may result. This can lead to an
increasing number of falls and related injuries, and you may
need to use a cane or walker or a wheelchair to ensure your
own safety.
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Depression
and mood disturbances |
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Seborrheic
dermatitis - This is
a rash caused by overactivity of the oil glands in the
skin. It is
usually seen on the face.
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Trouble
speaking (dysarthria) or swallowing
(dysphagia) - This
may occur with tongue tremor, or inability to move the muscles
of the mouth and tongue, but it usually does not occur until
very late in the disease.
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Side
effects of medications - See
above, under Diagnosis
and Treatment.
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| Prognosis |
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The
prognosis for PD is good. PD does not itself
cause death, although PD patients are at increased risk for
dying of other conditions, such as pneumonia.
PD is a
slowly progressive disease, and some people initially present
with a hand tremor, which is the only symptom which is noted
for the next 8 to 15 years. The disease may be
staged in terms of severity according to various standardized
scales (e.g. Hoehn and Yahr or UPDRS scales), and there is a
typical time course of progression through the stages of the
disease.
Typically,
the early presentation involves mild symptoms such as tremor
of an isolated body part (or body parts). These initial symptoms
do not cause much disturbance of function and therefore do not
generally require medication. After about 5 years,
there is an increase in muscle tone (rigidity) and a
difficulty in initiating movements. At this point,
medication must be prescribed to alleviate symptoms and to
maintain the ability to perform daily activities. After about 10 years,
mobility is usually impaired and walking aids may be
required. Higher
doses of medication are generally needed, and symptoms may be
incompletely alleviated, even with optimal treatment. At about 12 years,
debilitating symptoms such as dysphagia (difficulty
swallowing) may be present, and a wheelchair is often required
(due to the inability to maintain posture and for reasons of
general immobility).
Intractable side effects of medication are often
present at these later stages of disease, and symptoms may not
respond well to the medication. At this time, the only
successful treatment is surgical.
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| Other |
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