Parkinson’s Disease was first described in 1817 by Dr. James Parkinson,
a British physician after whom the disease is named.
The disease is characterized by a “TRAP”
“T” for
tremor, usually a slow resting tremor of the limb.
“R” for rigidity which is stiffness of the extremity and difficulty
with passive movement.
“A” Achyesthesia or bradykinesia which is slowness of movement.
“P” for poor balance or postural instability.
Parkinson’s Disease is diagnosed clinically. They have to have at least
two of these symptoms present. There has to be an evidence of progression and
exclusion of other potential diseases that can present with Parkinson’s
features. Often, patients present with tremors although they can be a form
of Parkinson’s which presents primarily with slowness and stiffness without
a tremor. The individual may have difficulty with day-to-day activities such
as dressing, walking, and may experience balance problems, difficulty getting
out chairs, and turning in bed. There may be decreased facial expression, difficulty
with writing, usually in the description as very small letters with their writing.
It affects about 1 in 100 people over the age of 60 with an average age of
onset of about 60 years of age. It can affect younger people. More often, they
have a family history. Parkinson’s Disease is a neural degenerative disease
that progresses over time. There is degeneration of the area of the brain called
Substantia Nigra. These cells produce a chemical called dopamine, which is
an important chemical. When these cells are damaged and depleted, symptoms
of Parkinson’s appear. About 8-% of the cells are damaged before symptoms
are clinically evident. At present we have treatments primarily to decrease
the symptoms of Parkinson’s Disease. There are some potential treatments
to slow down the progression.
Is Parkinson’s Disease Inherited?
There is a family history of Parkinson’s Disease in 5-10% of patients.
It may affect people in the same generation like brother or sister or in separate
generations. There are clearly some environmental toxins which are a cause
of Parkinson’s Disease including manganese, carbon monoxide, and rarely
certain pesticides. There is also a “street drug” (MPTP) which
causes Parkinson’s in young patients. Neurogene mutations have been associated
with Parkinson’s Disease in familio forms of Parkinson’s. Most
cases of Parkinson’s Disease are not familio. It appears there is a combination
of a genetic risk with an irritability to environmental toxin and advancing
age which puts these individuals at risk.
Diagnosis of Parkinson’s Disease
The diagnosis of Parkinson’s Disease is made by a physician. This is
primarily made on a clinical examination looking at further features of tremors,
rigidity, bradykinesia, loss of postural reflexes, and exclusion of other factors.
Testing may be done to exclude other diseases such as imaging of the brain
to rule out a stroke or tumor, certain blood tests to rule out viral dysfunction
which can present like Parkinson’s features. There are other forms of
conditions which can look like Parkinson’s Disease and these are called
Parkinson’s Syndromes. These include effects of certain medications that
can look like Parkinson’s particularly psychotropic medications (antipsychotics,
Reglan, Recerpine, and some occasional calcium channel blockers). Other conditions
include progressive super nuclear palsy (PSP). These present usually with initial
balance and frequent falls. These are in the trunk and eventually loss of eye
movements. They usually begin after age 50 and progress more rapidly than Parkinson’s
Disease. Dementia develops later in the disease. There is no treatment available
since usual Parkinson’s medications are not effective. Another form is
corticobasal degeneration (CBD). This is the least common of the atypical forms
of Parkinsonisms. Patients present asymmetrically and progress very rapidly.
They usually develop after age 40 and include asymmetrical bradykinesia, rigidity,
with abnormal dystonia limbs, loss of posture, and language difficulty. There
is no specific treatment available for this. Multi-system atrophy (MSA) is
a neurogenerative disease of unknown cause. This may be difficult to distinguish
initially from Parkinson’s Disease but this file is common and progresses
rapidly. Mean age of onset is 50. They present again with bradykinesia, poor
reflexes, but they can also have associated difficulty with blood pressure
control, difficulty with coordination, impotence, decreased sweating, and constipation.
They may have an initial response to mild Parkinson’s medication but
at later stage they develop an intolerance to this. They do not benefit from
deep brain stimulation. Vascular Parkinson’s is small strokes which cause
the patient to look like a Parkinson’s patient and can be picked up on
imaging of the brain. There is more of a step-wise deterioration as recurrent
strokes.
Treatment for Parkinson’s Disease
Parkinson’s Disease responds very well to medications. The most common
medication is (L-dopa). This treatment has been available for almost 30 years
and has revolutionized the treatment of Parkinson’s Disease. L-dopa is
a precursor for dopamine. It is transported through the gut, to the brain or
at least by the brain cells. It is available in an immediate release or a long
acting version. Also, this is called Sinemet and it is combined with a medication
called Carbidopa which decreases the conversion of dopamine in the gut and
therefore decreases nausea. There is a new medication called Stalevo which
is a combination of carbadopa/levadopa with Comtan which allows even more of
the L-dopa to get into the brain by decreasing the conversion of L-dopa in
the peripheral system. Other treatments that can be started early include Amantadine
which is an antiviral drug which helps decrease some of the tremors and fatigue
seen with Parkinson’s Disease. Anticholerginics such as Artane also can
decrease rigidity and tremors in Parkinson’s Disease if started early.
Agents such as dopamine agonists act directly as a dopamine receptor and the
most common ones were recently released, such as Mirapex or Requip. Older agents
still can be used but have more side effects particularly with nausea, lightheadedness,
and hypertension. These include Polydial, Permax. Side effects of these medications
include hallucinations, orthostatic drop in blood pressure, and drowsiness
in the daytime. There are some protective agents which can help slow down the
disease including Selegeline which may also mask the symptomatic effect, Coenzyme
Q10 which in larger dosages has suggested that it may slow down the progression
of the disease.
Treatment options in the younger patients: A dopamine agonist may be started
early on and then later an L-dopa started. In an elderly patient, they may
start treatment with L-dopa then add in a dopamine agonist later. The disease
is progressive and the patient may develop motor fluctuations in the disease.
These are problems where the medication stops working before the next dose
and this is called an “off period”. There may also be times when
the medication is taken and there are uncontrollable movements of the head
and limbs called dyskinesias. These can sometimes be treated by adjustments
of medications. If the patient is below age 70 and has no underlying dementia
and is a good surgical candidate and if they are having significant motor fluctuations
they may be a candidate for surgery. Previous treatments included resective
surgery. Now the standard care is usually deep brain stimulation most commonly
thalamic which releases tremors, rigidity, bradykinesia and gait disorders.
Other locations for the simulators include thalamic which are more important
for tremors but not for other features of Parkinson’s Disease, globis
palatis which helps reduce tremor, rigidity, and bradykinesia and gait disorders.
This should be done in a specialized center since there needs to be close follow-up
on adjustments of the stimulator.
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