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it does not help bradykinesia or balance problems.
69. What is pallidotomy?
Pallidotomy Pallidotomy is a surgical procedure that can decrease
a surgical procedure
dyskinesia, reduce tremor, and improve bradykinesia.
that can decrease
The ideal candidate is a young person who is healthy
dyskinesia, reduce
with no impairment in thinking and memory. The per-
tremor, and improve
bradykinesia by
son should have a good response to PD drugs. This is
releasing a brake in
unlike thalamotomy, where a good response to drugs is
the globus pallidus.
not necessary. Remember, tremor may not respond to
PD drugs, while bradykinesia does, and dyskinesia
results from PD drugs (levodopa). Pallidotomy is simi-
lar to thalamotomy except the target region is the
globus pallidus. This region of the brain is known to be
overactive in animal models of PD. The interruption of
the outflow from the globus pallidus inhibits (blocks)
the pathway that causes dyskinesias. The interruption
of the outflow from the globus pallidus also releases a
brake that blocks the substantia nigra. The results of
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pallidotomy on reducing dyskinesia, reducing tremor,
and increasing movement are less consistent than the
results of DBS on the globus pallidus or the subthala-
mic nucleus. Pallidotomy is done on the side of the
brain opposite the side of the most dyskinesia or the
most severe bradykinesia. Bilateral simultaneous palli-
dotomy carries the risk of speech and thinking diffi-
culty. As with any surgery, there are risks, especially
with older people. There is a 1% to 3% risk of stroke or
hemorrhage with thalamotomy or pallidotomy.
70. What is DBS?
Stimulation surgery or deep brain stimulation (DBS) Deep brain
stimulation
refers to implanting a probe or electrode, a stimulator
a treatment in which
into a clearly defined, abnormally discharging brain
a probe or electrode
region a region generating static. This is usually,
is implanted and
used to stimulate a
but not always, the same region targeted in ablative or
clearly defined,
destructive surgery. By generating a blocking or
abnormally discharg-
inhibiting counter-current, the effects of the static are
ing brain region to
block the abnormal
lessened or negated. Technically, DBS is a mis-
activity.
nomer the abnormal discharging brain region isn t
stimulated; rather, it s blocked or inhibited by a reverse
or counter-current.
There is renewed interest in DBS because is it seen as
a refinement of thalamotomy and pallidotomy. How-
ever, instead of destroying a section of brain tissue,
DBS uses a high-frequency electrical charge to stimu-
late the brain. Where the electrode is placed in the
brain determines which symptoms will be alleviated.
Two surgeries are required. In one surgery, a micro-
electrode is implanted in a specific region to remain
there permanently. Wires from the implanted elec-
trode are then passed beneath the skin to a small bat-
tery pack placed under the skin near the shoulder. This
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device is then adjusted to the patient s own needs to
regulate the frequency in the electrode. The patient
will be able to turn it off and on by means of a magnet.
When the device is on, the stimulation will stop the
tremor, the dyskinesia, or improve bradykinesia within
a few seconds. When it is turned off, the tremor or
dyskinesia will return. The major advantage of this
surgery is that it has fewer complications than thalam-
otomy or pallidotomy, and there is significant im-
provement of symptoms, sometimes requiring smaller
amounts of PD drugs. The regions targeted by DBS
are the thalamus, the globus pallidus, and the subthal-
amic nucleus. Increasingly, the subthalamic nucleus is
becoming the preferred target. The subthalamic
nucleus is located below the thalamus, and it acts as
brake on the substantia nigra. Studies have compared
DBS to thalamotomy and pallidotomy, and although
sufficient data still need to be collected, these studies
have shown promising results in favor of DBS.
71. What is restorative surgery?
Restorative or transplantation surgery transfers or
implants dopamine-producing cells into the striatum.
The striatum, from the Latin stripped-substance, is
named because of the large number of fibers that cross
it giving it a stripped or braided appearance. In the
striatum fibers project downward from the cerebral
cortex, co-mingling with dopamine fibers projecting
upward from the substantia nigra. The striatum is
composed of two parts: the caudate nucleus and the
putamen. The putamen is more affected in PD.
Cells are transplanted into the striatum because it s
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