Parkinson’s Disease
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. The patient has to have at least two of the above symptoms present. There also has to be an evidence of progression and an exclusion of other potential diseases that can present with Parkinson’s features. Often, patients present with tremors although there are forms of Parkinson’s which present 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 or difficulty with writing, usually causing the use of very small letters with writing. Parkinson's Disease affects about 1 in 100 people over the age of 60 with an average age of onset at about 60 years of age, however it can affect younger people. It can affect younger people. 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 in this area 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 and some 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 features of tremors, rigidity, bradykinesia, loss of postural reflexes, and the 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 and certain blood tests to rule out viral dysfunction which can present like Parkinson’s features. There are other 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 cells. It is available in an immediate release or a long
acting version. The most common medication used is Sinemet with a medication
called Carbidopa which decreases the conversion of dopamine in the gut and
therefore decreases nausea. There is a 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, an antiviral drug which can help decrease some of the tremor and fatigue
seen with Parkinson’s Disease. Anticholerginics such as Artane also can
decrease rigidity and tremor in Parkinson’s Disease if started early.
Agents such as dopamine agonists act directly on a dopamine receptor. The
most common dopamine agonists used are Mirapex and Requip. There are some protective agents which can help slow down the
disease including Selegeline which may also mask the symptomatic effects and Coenzyme
Q10 which in larger dosages may slow down the progression
of the disease.
When treating younger patients for Parkinson's Disease, a dopamine agonist may be started
early on and then an L-dopa started. An elderly patient may
start treatment with L-dopa then add in a dopamine agonist later. These are problems where the medication stops working before the next dose is to be given 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 problems 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 current 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.
