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Copyright 2002 by
Nikicj5/ and Medical Madness Newsletter@
*Graphics Designed by Alexgram1*
Parkinson
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What Is It?
Parkinson's disease is a chronic movement disorder (a problem involving body
motions) that causes resting tremor, rigidity, slowed body movements, unstable
posture and abnormal gait.
It happens when neurons (nerve cells) in a part of the brain called the
substantia nigra gradually die. These cells normally produce dopamine, a
chemical that helps relay messages between areas of the brain that control body
movement. The death of substantia nigra cells leads to
abnormally low levels of dopamine,
and this causes difficulty in controlling muscle tension and muscle movement,
both at rest and during periods of activity.
Parkinson's disease currently affects about 500,000 Americans, with
approximately 50,000 new cases diagnosed each year.
It is generally a disease of late middle age, with typical onset at about age
60;
however, about 5 percent of patients have early-onset Parkinson's disease and
are younger than 40 years old when symptoms begin. Internationally, Parkinson's
disease affects about one to two in every 1000 persons, striking Europeans and
North Americans more frequently than Asians or Africans.
It is also slightly more common in men than in women.
So far, scientists have not determined the reason why some people develop
Parkinson's disease and others do not.
The greatest risk factors for Parkinson's disease are increasing age and a
family history of the disease.
Some experts blame free radicals (unstable molecules that are produced in the
brain as a result of its normal chemical reactions), which ultimately may damage
the brain through a chemical process called oxidation. Another theory suggests
that Parkinson's disease may be caused by the toxic effects of drugs. This is
supported by evidence that MPTP, a contaminant of illicit heroin synthesis
during the 1970s, has been linked to some cases of Parkinson's disease.
Additional evidence suggests that Parkinson's disease may be related to
environmental toxins, especially pesticides, because some experts claim to have
found higher rates of Parkinson's disease in rural areas where farming is
intense and residents drink well water. Although one study linked Parkinson's
disease to an inherited genetic problem, this study analyzed only one family in
whom Parkinson's disease affected several generations. So far, follow-up testing
in other families with Parkinson's disease has not confirmed the same genetic
abnormality.
Symptoms
Parkinson's disease usually
begins as a slight tremor or stiffness
involving the
arm or leg on one side of the body.
The tremor is prominent at rest and is regular, typically occurring at a rate of
three to six times per second. The Parkinson's disease tremor usually worsens
under stress, improves with voluntary movement of the affected limb, and may
disappear entirely during sleep. In the earliest stages, Parkinson's disease may
be evident only as a "pill-rolling" tremor involving the thumb and index finger.
As the illness progresses, the tremor may become more widespread, eventually
affecting limbs on both sides of the body. In addition to the classic tremor,
Parkinson's disease also causes limb rigidity,
a slowing of body movements (bradykinesia),
unstable posture and a characteristic abnormal gait. When bradykinesia affects
the facial muscles, it causes drooling, disrupts normal eye blinking, interferes
with spontaneous facial expressions and eventually leads to a mask-like
appearance.
Bradykinesia of other muscles may affect the patient's ability to walk and to
perform activities of daily living, such as washing, dressing, or using eating
utensils. Handwriting also becomes small, shaky and often illegible.
In many Parkinson's disease patients, problems with unsteady balance and posture
may make it hard for them to lower themselves into a chair or to rise from one.
Walking is accomplished with small, shuffling steps and a stooped posture,
usually without the normal arm-swinging motions.
Other symptoms of Parkinson's disease may include:
*Depression
*Anxiety
*Disturbed sleep
*Memory loss
*Slurred or abnormally soft speech
*Difficulty chewing or swallowing
*Constipation
*Impaired bladder control
*Abnormal regulation of body temperature
*Increased sweating
*Sexual dysfunction
*Cramps, numbness, tingling or pain in the muscles
Diagnosis
On physical examination, your doctor will look for symptoms of Parkinson's
disease, especially for the classic Parkinson's disease tremor, slowness of
movement and gait problems.
Your doctor will also perform a thorough neurologic examination.There is
currently no specific diagnostic procedure or laboratory test to establish the
diagnosis of Parkinson's disease. For this reason, doctors diagnose Parkinson's
disease based on the results of a physical and neurologic examination.
If a patient's symptoms improve once he or she receives medication for
Parkinson's disease, this serves as evidence that the diagnosis is correct.
In the future, improvements in newer neuroimaging technologies, such as positron
emission tomography (PET) and functional MRI, may help to confirm a suspected
diagnosis of Parkinson's disease.
Expected DurationParkinson's disease is a chronic, progressive illness. In most
patients, 70 percent to 80 percent of brain cells in the substantia nigra are
already lost by the time their Parkinson's disease symptoms first appear.
Prevention
Because doctors are not sure what causes Parkinson's disease, there is currently
no proven way to prevent it.
TreatmentMedication
Although there is currently no cure for Parkinson's disease, its symptoms can be
treated with several different types of medication.
Since the symptoms of Parkinson's disease are caused by degeneration of
dopamine-producing neurons in the brainstem, most existing therapeutic
strategies for Parkinson's disease are "dopaminergic" — that is, the medications
either boost dopamine levels in the brain or mimic the effects of dopamine on
target cells.
The first major decision faced by patients and their physicians is when to
initiate treatment in the early stages of the disease. When symptoms are
apparent but not overly troublesome, medication may not be necessary,
particularly since there is some evidence that early treatment can in some cases
predispose patients to later side effects and other complications.
Treatment is usually begun when symptoms interfere with work performance or
management of household affairs and other activities, or when difficulty with
walking and balance becomes significant.
The most effective therapy for Parkinson's disease is levodopa (Atamet, Larodopa,
Sinemet), a medication that is converted to dopamine in the brain
Levodopa
is usually prescribed in combination with
carbidopa
to increase its effectiveness and limit side effects.
Nearly all patients
with Parkinson's disease experience a rapid improvement in symptoms after
starting levodopa therapy. Unfortunately, long-term use of levodopa is
associated with troublesome complications in 75 percent of patients. These
complications include fluctuations in the response of motor symptoms; abnormal,
uncontrollable movements termed dyskinesias, which sometimes can be severe and
disabling; and mental impairments such as confusion or hallucinations.
As noted above, there is some evidence that long-term use of levodopa may
increase the risk of developing these complications. Some physicians therefore
prefer to minimize the duration and dosage of levodopa therapy in Parkinson's
disease.
Several alternative medications may be used either alone or in combination with
levodopa to treat Parkinson's disease symptoms.
For mild symptoms in early Parkinson's disease, amantadine (Symmetrel) or
anticholinergic medications, such as trihexyphenidyl (Artane, Trihexane, Trihexy)
or benztropine (Cogentin), may be helpful.
*Amantadine
promotes the release of stored dopamine inside the brain, but it may work only
briefly in some patients.
*Anticholinergic
medications are particularly effective against tremor, but their use may be
limited by side effects such as confusion and hallucinations, especially in
elderly patients.
In patients with early Parkinson's disease, the drug selegiline (Carbex,
Eldepryl) also produces a mild improvement in symptoms, possibly through a
protective effect on the remaining dopamine-producing brain cells, but this
explanation is controversial.
*Dopamine
agonist medications — such as bromocriptine (Parlodel), pergolide (Permax),
pramipexole (Mirapex) and ropinirole (Requip) — may be used alone to delay the
need for levodopa, or when used in combination with levodopa, they may increase
its effectiveness or reduce the necessary dose. Dopamine agonists function by
mimicking the effects of dopamine on target brain cells, but they are in general
less effective than levodopa, and most patients require the addition of levodopa
within a few years.
These medications can cause lowering of the blood pressure and faintness,
particularly when patients first start taking them, but the effect is minimized
if the dosage is increased slowly. Depending upon the dopamine agonist used,
other rare side effects are possible, including skin inflammation, ankle
swelling or attacks of drowsiness, so a physician should be consulted before and
during therapy.
*Drugs called COMT
(catechol-O-methyltransferase inhibitors offer another alternative therapy for
use in combination with levodopa. COMT inhibitors, such as entacapone (Comtan)
and tolcapone (Tasmar), block the enzyme that breaks down dopamine and levodopa,
thereby prolonging the action of dopamine in the brain and increasing the
effectiveness of levodopa.
Depression is a fairly common problem in Parkinson's disease,
and many patients can benefit from treatment with antidepressant medications.
Symptoms of depression include not only depressed mood or tearfulness, but also
decreased appetite, disturbed sleep (especially early awakening), decreased
interest in pleasurable pursuits or activities, decreased energy level, thoughts
of worthlessness, guilt or suicide. A physician should be consulted if any of
these symptoms are apparent, and the patient should receive medical attention
immediately if he or she may be suicidal.
In addition to treatment with medications, some Parkinson's disease patients
find that regular exercise and a balanced diet help to improve their overall
sense of well-being and body control.
Surgery
Surgical treatments are considered when patients have not responded adequately
to medications. Existing surgical treatments involve either the creation of
small, precise lesions or the implantation of stimulating electrodes in specific
brain regions that appear to be overactive in Parkinson's disease.
Thalamotomy and thalamic stimulation are effective in relieving tremor that does
not respond to medications in about 70 percent of cases.
Pallidotomy is used primarily to relieve dyskinesias caused by levodopa therapy,
but also provides some relief from rigidity and tremor
Subthalamic nucleus stimulation
is also effective in relieving Parkinson's disease symptoms and reducing
levodopa-induced dyskinesias. Finally, implantation of fetal dopaminergic tissue
is a promising but experimental procedure. Results so far have been mixed, and
further work is needed to solve some of the difficulties associated with this
procedure.
When To Call A Professional
Call your doctor if you develop any of the symptoms of Parkinson's disease,
especially if you notice a persistent tremor or stiffness anywhere in your body,
or if you have trouble walking or rising from a chair.
Prognosis
Although levodopa will not cure Parkinson's disease, it reduces Parkinson's
disease symptoms in about 75 percent of patients.
Additional InfoNational Parkinson Foundation
Bob Hope Parkinson Research Center
1501 N.W. 9th Avenue
Bob Hope Road
Miami, Florida 33136-1494
Phone: (305) 547-6666
Toll-Free: (800) 327-4545
Fax: (305) 243-4403
http://www.parkinson.org/
The American Parkinson Disease Association
1250 Hylan Blvd.
Staten Island, NY 10305-1946
Toll-Free: (800) 223-2732
http://www.apdaparkinson.com/
Parkinson's Disease Foundation
710 W. 168th Street
New York, NY 10032
Toll-Free: (800) 457-6676
http://www.parkinsons-foundation.org/
Stem Cells May Help Parkinson's
Jeanie Davis
WebMD Medical News Reviewed By Brunilda Nazario, MD
Nov. 7, 2002
-- Scientists have successfully converted adult stem cells -- unprogrammed,
blank-slate cells -- into nerve cells that produce dopamine, the brain chemical
missing in Parkinson's disease. So far, it's just been done in a laboratory dish
and in rat brains. But if this can be done in human brains and with human cells,
it may become a new treatment for Parkinson's disease.
Lorraine Iacovitti, PhD, professor of neurology at Thomas Jefferson University
Medical College in Philadelphia, presented her report at the Society for
Neuroscience meeting in Orlando this week.
In previous work with rats, Iacovitti and colleagues showed that transplanted
nerve stem cells could develop into nerve cells that produced tyrosine
hydroxylase, the enzyme needed to make dopamine.
To see if this worked with human nerve cells, Iacovitti grew brain stem cells in
a laboratory dish. Using a mix of human growth hormones and nutrients, the
researchers found they could coax about 25% of the stem cells to make tyrosine
hydroxylase in the dish.
This proves that stem cells have the capacity to manufacture dopamine.
In fact, when they removed the growth factor cocktail, the cells continued to
produce the enzyme for five more days, Iacovitti says in her report.
They hope to be able to develop this as a treatment for Parkinson's disease in
people, Iacovitti says in a news release.
© 2002 WebMD Inc. All rights reserved.
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