The following is extracted from Chapter 1: What Is Parkinson's Disease?
by Abraham Lieberman, M.D.
PD is characterized by four main features: rigidity or stiffness of the
arms, legs or neck; tremor, usually of the hands; bradykinesia or
slowness and reduction of movement; and postural instability (loss of
balance). Other symptoms may accompany the main features, including
depression, dementia or confusion, postural deformity, speech and
swallowing difficulty, drooling, dizziness on standing, impotence,
urinary frequency and constipation.
When rigidity, tremor, slowness of movement and loss of balance
dominate, when the course of the disease is slow with disability
occurring 10 to 20 years after diagnosis, and when there is no obvious
cause, then the condition is referred to as idiopathic PD. Patients with
the above features, on post-mortem examination, show loss of the dark,
pigmented neurons (nerve cells) in two areas of the brain: the
substantia nigra (latin for "black substance") and the locus ceruleus
("blue substance"). The dead and dying cells contain Lewy bodies. While
Lewy bodies are found in other diseases, the diagnosis of idiopathic PD
can only be made with certainty if Lewy bodies are found in the
substantia nigra and locus ceruleus after death.
Paralleling the loss of nerve cells in the substantia nigra is the loss
of dopamine, a chemical which carries messages from one nerve cell to
another. The loss of dopamine is most marked in that part of the brain
called the striatum (or "stripped substance"). The striatum consists of
two parts: The caudate nucleus and the putamen. Primary treatment of PD
consists of giving levodopa (in the U.S. via Sinemet or a generic form
thereof), which is converted to dopamine in the substantia nigra and the
striatum, and replaces the missing dopamine. Patients with idiopathic PD
usually respond well to levodopa. In fact, a successful response to
levodopa confirms the clinical diagnosis of PD.
When early in the disease there is a mixture of the main features with
other symptoms; when the course of the disease is rapid with marked
disability occurring within five years; or when there is no response to
levodopa, the condition is called Parkinson Disease Plus (PD+). The term
PD+ encompasses a number of disorders including Progressive Supranuclear
Palsy (PSP), Cortico-Basilar Degeneration (CBD) and MultiSystem Atrophy
(MSA). MultiSystem Atrophy includes the Shy-Drager Syndrome (SDS),
Striatonigral Degeneration (SND) and OlivoPontoCerebellar Atrophy
(OPCA). The PD+ disorders differ from idiopathic PD in that, although
there is a loss of nerve cells in the substantia nigra, the main changes
occur elsewhere. Though symptoms may resemble PD, Lewy bodies are not
found in these disorders.
There are also a number of disorders with parkinsonian features for
which the cause is known and which have a variable rate of progression
and response to levodopa. These disorders are referred to as Parkinson
Syndrome (PS) and include multiple small strokes and poisoning by
manganese, carbon monoxide and cyanide. PS also includes pugilistic
parkinsonism, a disorder of professional boxers who receive multiple
blows to the head and in whom symptoms progress even after they stop
fighting. Pugilistic parkinsonism affected Jack Dempsey, Joe Lewis and,
more recently, Muhammad Ali.
In addition to the above disorders, which are permanent, there are
several drug induced Parkinson disorders that are reversible on stopping
the drug. Drugs that cause PS include tranquilizers such as
chlorpromazine (Thorazine), fluphen-zine (Prolixin) and haloperidol
(Haldol). In addition, drugs such as metochlopramide (Reglan) and
prochlorperazine (Compazine), used to treat nausea but similar to the
tranquilizers, may also cause PS. These drug-induced disorders are not
associated with a loss of nerve cells in the substantia nigra and differ
from the permanent PS associated with the nerve toxin MPTP
which does result in loss of nerve cells in the substantia nigra.
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The following is extracted from Appendix C: Stages of Parkinson's
Disease:
The following scale, developed by Hoehn and Yahr, is the most widely
used one to describe PD:
Stage I: Signs of Parkinson's disease are unilateral (affecting one
side of the body only).
Stage II: Signs of Parkinson's disease are bilateral. Balance is not
impaired.
Stage III: Signs of Parkinson's disease are bilateral and balance is
impaired.
Stage IV: Parkinson's disease is functionally disabling.
Stage V: Patient is confined to bed or wheelchair.
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