Deep
Brain Stimulation for Parkinsons
 |
Deep
brain stimulation (DBS) is a surgical procedure used to
treat a variety of disabling neurological
symptoms—most commonly the
debilitating symptoms of Parkinson’s
disease (PD), such as tremor,
rigidity, stiffness, slowed movement,
and walking problems. The procedure
is also used to treat essential
tremor, a common neurological
movement disorder. At present,
the procedure is used only for
patients whose symptoms cannot
be adequately controlled with
medications. |
What
is Deep Brain Stimulation for Parkinson's
Disease?
DBS
uses a surgically implanted, battery-operated
medical device called a neurostimulator—similar
to a heart pacemaker and approximately
the size of a stopwatch—to deliver
electrical stimulation to targeted areas
in the brain that control movement, blocking
the abnormal nerve signals that cause
tremor and PD symptoms.
Before the procedure,
a neurosurgeon uses magnetic resonance
imaging (MRI) or computed tomography (CT)
scanning to identify and locate the exact
target within the brain where electrical
nerve signals generate the PD symptoms.
Some surgeons may use microelectrode recording—which
involves a small wire that monitors the
activity of nerve cells in the target
area—to more specifically identify
the precise brain target that will be
stimulated. Generally, these targets are
the thalamus, subthalamic nucleus, and
globus pallidus. The
DBS system consists of three components:
the lead, the extension, and the neurostimulator.
The lead (also called an electrode)—a
thin, insulated wire—is inserted
through a small opening in the skull and
implanted in the brain. The tip of the
electrode is positioned within the targeted
brain area.
The extension is
an insulated wire that is passed under
the skin of the head, neck, and shoulder,
connectng the lead to the neurostimulator.
The neurostimulator (the "battery
pack") is the third component and
is usually implanted under the skin near
the collarbone. In some cases it may be
implanted lower in the chest or under
the skin over the abdomen.
Once the system
is in place, electrical impulses are sent
from the neurostimulator up along the
extension wire and the lead and into the
brain. These impulses interfere with and
block the electrical signals that cause
PD symptoms.
Is there
any treatment?
Unlike previous
surgeries for PD, DBS does not damage
healthy brain tissue by destroying nerve
cells. Instead the procedure blocks electrical
signals from targeted areas in the brain.
Thus, if newer, more promising treatments
develop in the future, the DBS procedure
can be reversed. Also, stimulation from
the neurostimulator is easily adjustable—without
further surgery—if the patient’s
condition changes. Some people describe
the stimulator adjustments as "programming."
What is
the prognosis?
Although most patients
still need to take medication after undergoing
DBS, many patients experience considerable
reduction of their PD symptoms and are
able to greatly reduce their medications.
The amount of reduction varies from patient
to patient but can be considerably reduced
in most patients. The reduction in dose
of medication leads to a significant improvement
in side effects such as dyskinesias (involuntary
movements caused by long-term use of levodopa).
In some cases, the stimulation itself
can suppress dyskinesias without a reduction
in medication.
What research
is being done?
The NINDS supports
research on DBS to determine its safety,
reliability, and effectiveness as a treatment
for PD. Currently, NINDS-supported scientists
are trying to determine the site(s) in
the brain where DBS surgery will be most
effective in reducing PD symptoms. These
researchers are also comparing DBS to
other PD therapies to find out which is
more effective.
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