Parkinson's Disease (cont.)
Surgery
Treating Parkinson's disease with surgery was once a common practice. But after the discovery
of levodopa, surgery was restricted to only a few cases. Studies in the past few
decades have led to great improvements in surgical techniques, and surgery is
again being used in people with advanced Parkinson's disease for whom drug therapy is no longer
sufficient.
Pallidotomy and
Thalamotomy. The earliest types of surgery for Parkinson's disease involved selectively
destroying specific parts of the brain that contribute to the symptoms of the
disease. Investigators have now greatly refined the use of these procedures. The
most common of these procedures is called pallidotomy. In this procedure, a
surgeon selectively destroys a portion of the brain called the
globus pallidus.
Pallidotomy can improve symptoms of tremor, rigidity, and bradykinesia, possibly
by interrupting the connections between the globus
pallidus and the striatum or thalamus. Some studies have also found that
pallidotomy can improve gait and balance and reduce the amount of levodopa
patients require, thus reducing drug-induced dyskinesias and dystonia. A related
procedure, called thalamotomy, involves surgically destroying part of the
brain's thalamus. Thalamotomy is useful primarily to reduce tremor.
Because these procedures cause permanent destruction of brain tissue, they
have largely been replaced by deep brain stimulation for treatment of
Parkinson's disease.
Deep Brain Stimulation.
Deep brain stimulation, or DBS, uses an electrode
surgically implanted into part of the brain. The electrodes are connected by a
wire under the skin to a small electrical device called a pulse generator that
is implanted in the chest beneath the collarbone. The pulse generator and
electrodes painlessly stimulate the brain in a way that helps to stop many of
the symptoms of Parkinson's disease. DBS has now been approved by the U.S. Food and Drug
Administration, and it is widely used as a treatment for Parkinson's disease.
DBS can be used on one or both sides of the brain. If it is used on just one
side, it will affect symptoms on the opposite side of the body. DBS is primarily
used to stimulate one of three brain regions: the subthalamic nucleus, the
globus pallidus, or the thalamus. However, the subthalamic nucleus, a tiny area
located beneath the thalamus, is the most common target. Stimulation of either
the globus pallidus or the subthalamic nucleus can reduce tremor, bradykinesia,
and rigidity. Stimulation of the thalamus is useful primarily for reducing
tremor.
DBS usually reduces the need for levodopa and related drugs, which in turn
decreases dyskinesias. It also helps to relieve on-off fluctuation of symptoms.
People who initially responded well to treatment with levodopa tend to respond
well to DBS. While the benefits of DBS can be substantial, it usually does not
help with speech problems, "freezing," posture, balance, anxiety, depression, or
dementia.
One advantage of DBS compared to pallidotomy and thalamotomy is that the
electrical current can be turned off using a handheld device. The pulse
generator also can be externally programmed.
Patients must return to the medical center frequently for several months
after DBS surgery in order to have the stimulation adjusted by trained doctors
or other medical professionals. The pulse generator must be programmed very
carefully to give the best results. Doctors also must supervise reductions in
patients' medications. After a few months, the number of medical visits usually
decreases significantly, though patients may occasionally need to return to the
center to have their stimulator checked. Also, the battery for the pulse
generator must be surgically replaced every three to five years, though
externally rechargeable batteries may eventually become available. Long-term
results of DBS are still being determined. DBS does not stop Parkinson's disease from
progressing, and some problems may gradually return. However, studies up to
several years after surgery have shown that many people's symptoms remain
significantly better than they were before DBS.
DBS is not a good solution for everyone. It is generally used only in people
with advanced, levodopa-responsive Parkinson's disease who have developed dyskinesias or other
disabling "off" symptoms despite drug therapy. It is not normally used in people
with memory problems, hallucinations, a poor response to levodopa, severe
depression, or poor health. DBS generally does not help people with "atypical"
parkinsonian syndromes such as multiple system atrophy, progressive supranuclear
palsy, or post-traumatic parkinsonism. Younger people generally do better than
older people after DBS, but healthy older people can undergo DBS and they may
benefit a great deal.
As with any brain surgery, DBS has potential
complications, including stroke or brain hemorrhage. These complications are
rare, however. There is also a risk of infection, which may require antibiotics or even replacement of parts of the
DBS system. The stimulator may sometimes cause speech problems, balance
problems, or even dyskinesias. However, those problems are often reversible if
the stimulation is modified.
Researchers are continuing to study DBS and to develop ways of improving it.
They are conducting clinical studies to determine the best part of the brain to
receive stimulation and to determine the long-term effects of this therapy. They
also are working to improve the technology used in DBS.
Next: Complementary and Supportive Therapies »
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