What is Parkinson's Disease?Parkinson's disease (PD) belongs to a
group of conditions called motor system disorders, which are the result of the
loss of dopamine-producing brain cells. The four primary symptoms of PD are
tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness
of the limbs and trunk; bradykinesia, or slowness of movement; and postural
instability, or impaired balance and coordination. As these symptoms become more
pronounced, patients may have difficulty walking, talking, or completing other
simple tasks. PD usually affects people over the age of 50. Early symptoms of
PD are subtle and occur gradually. In some people the disease progresses more
quickly than in others. As the disease progresses, the shaking, or tremor,
which affects the majority of PD patients may begin to interfere with daily
activities. Other symptoms may include depression and other emotional changes;
difficulty in swallowing, chewing, and speaking; urinary problems or
constipation; skin problems; and sleep disruptions. There are currently no
blood or laboratory tests that have been proven to help in diagnosing sporadic
PD. Therefore the diagnosis is based on medical history and a neurological
examination. The disease can be difficult to diagnose accurately. Doctors may
sometimes request brain scans or laboratory tests in order to rule out other
diseases.
Is there any treatment?At present, there is no cure for PD, but a variety of medications provide
dramatic relief from the symptoms. Usually, patients are given levodopa
combined with carbidopa. Carbidopa delays the conversion of levodopa into
dopamine until it reaches the brain. Nerve cells can use levodopa to make
dopamine and replenish the brain's dwindling supply. Although levodopa helps at
least three-quarters of parkinsonian cases, not all symptoms respond equally to
the drug. Bradykinesia and rigidity respond best, while tremor may be only
marginally reduced. Problems with balance and other symptoms may not be
alleviated at all. Anticholinergics may help control tremor and rigidity.
Other drugs, such as bromocriptine, pramipexole, and ropinirole, mimic the role
of dopamine in the brain, causing the neurons to react as they would to
dopamine. An antiviral drug, amantadine, also appears to reduce symptoms. In
May 2006, the FDA approved rasagiline to be used along with levodopa for
patients with advanced PD or as a single-drug treatment for early PD.
In some cases, surgery may be
appropriate if the disease doesn't respond to drugs. A therapy called deep brain
stimulation (DBS) has now been approved by the U.S. Food and Drug
Administration. In DBS, electrodes are implanted into the brain and connected to
a small electrical device called a pulse generator that can be externally
programmed. DBS can reduce the need for levodopa and related drugs, which in
turn decreases the involuntary movements called dyskinesias that are a common
side effect of levodopa. It also helps to alleviate fluctuations of symptoms and
to reduce tremors, slowness of movements, and gait problems. DBS requires
careful programming of the stimulator device in order to work
correctly.
What is the prognosis?
PD is both chronic, meaning it persists over a long period of time, and
progressive, meaning its symptoms grow worse over time. Although some people
become severely disabled, others experience only minor motor disruptions. Tremor
is the major symptom for some patients, while for others tremor is only a minor
complaint and other symptoms are more troublesome. No one can predict which
symptoms will affect an individual patient, and the intensity of the symptoms
also varies from person to person.
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