Dear Andrew and Meredith ([log in to unmask])
 
Following is a abstract of remarks made by Dr. Lauri Laitinen, neurosurgeon
from Stockholm, Sweden, at the YPSN meeting on April 16, 1994 in the SF Bay
Area.  He talks about some of the adverse effects of the Pallidotomy.
 
Pallidotomy 1993
Abstract of Remarks by Dr. Lauri Laitinen
Target Monthly, April / May 1994
 
Today there are about 20,000 people with Parkinson's disease in Sweden.  It
is estimated that 10 to 20 percent of these patients would benefit from
surgery.  This is more surgery than can be provided in Sweden with current
resources.
When L-dopa was introduced it was thought it would solve the problems for
Parkinson's patients.  Soon it was realized that the benefit of L-dopa
diminished over time.  Large doses of L-dopa may actually be toxic to the
brain.
There are two pathways from the putamen through the pallidum.  The primary
pathway goes from the putamen to the medial part of the pallidum.  The
alternate pathway goes to the subthalamic nucleus, a very deep part of the
brain, and back into the medial part of the pallidum.  Early surgery
interrupted the pathway coming out of the medial.  This reduced rigidity but
not tremor in patients.  However, this severance of the pathway also
prevented some normal movement.  Thus this surgery had as a side effect an
increase in bradykinesia (slowness).
Leksell and others modified the procedure by pushing the lesion back into the
lateral pallidum.  In this surgery tremor, bradykinesia and rigidity were
improved.  Little was written about this, as most neurosurgeons were
performing surgery in the thalamus for dramatic relief of tremor
(thalamotomy).  Leksell did not publish his results because he believed that
a neurosurgeon was biased in reporting his own results.  It was necessary to
actually perform scientific studies to properly remove any bias from the
reports.  In the years 1985 through 1988 only a few pallidotomies were
performed (1) to evaluate the effects of the surgery with the lesion in the
lateral pallidum, (2) to develop better methods for defining the target from
CT scans and (3) to develop equipment that would accept the scan data and
guide the probe to the proper area.
There is a problem when the skull is opened: some fluid escapes which causes
slight movement of the brain.  Adjustments must be made in redefining the
target to take into consideration this movement.  A probe is then inserted
through the hole, previously drilled, in the skull and put into the computed
target location.  Before creating the lesion, electric stimulation is
performed.  This allows the neurosurgeon to evaluate the probe's location.
 If the probe location is too close to general motor pathways, placement of a
lesion could result in permanent damage to motor pathways.  If the probe is
too close to the optic tract a lesion there could result in permanent damage
to the visual field (scotoma).  Stimulation should reveal these conditions
and the probe repositioned.  Further refinement of the procedure, has
virtually eliminated visual field damage as well as permanent damage to motor
pathways.
 
Microelectrode Recording
 
Learning about neuron activity in the pallidum is very important.  For the
first time in history we are able to learn about pallidal mechanisms.  A
technique called "microelectrode recording" is used to map neuron activity.
 There are risks associated with microelectrode recordings.  The first risk
is the prolonged surgery.  The actual time on the operating table can be up
to nine hours.  This can cause increased stress for the patient.  The second
risk is the extended time the brain is exposed to outside elements.  There is
a risk of contaminated air entering the brain and causing infections.  These
risks are very low.  The third risk is bleeding.  Microelectrode recording
uses a very sharp probe.  This probe can penetrate blood vessels causing a
hemorrhage.  When this happens, further recording must be terminated.  The
probe used to make the lesion in the pallidotomy is a blunt-tipped probe to
avoid the problems just referenced.  It is very important to do
microelectrode recording so scientists may learn about the pallidum; however,
this is research and the costs should not be charged to patients.  The extra
costs should be paid by funded research.  The reason for this is that
individual recording does not benefit the patient; however, studying the
recording of many patients will improve the surgical procedure for all future
patients.  This is very important for scientists and the risks mentioned are
low and should not deter patients from volunteering to increase the knowledge
of science.
 
The Pallidotomy
 
The typical pallidotomy takes about 55 minutes..  The patient is awake during
the surgery performing motor activity as needed by the surgeon.  The patient
also needs to respond to questions asked by the surgeon.  The patient has
been off medications for up to twelve hours before surgery.  This allows the
surgeon to see the patient's symptoms while on the operating table.  The
patient experiences the improvement immediately.  A good test of the surgical
procedure is to have the patient dance after surgery.  If the effect of the
surgery was good on the operating table, it is expected to be good for a long
time.  There is a regression period of about six weeks after surgery when the
patient may be depressed and tired.  Once this is over, the results seem to
be long-lasting.  In my 259 pallidotomies covering 1985 to 1993 no serious
side effects resulted from the surgery.  All patients were able to leave the
hospital within two days of the surgery.
 
Surgical Results
 
We now know where good and bad pallidotomy exists.  The lesion should not be
in the putamen .  A surgeon cannot guarantee perfect results every time.
 With good imaging and good surgical procedures the pallidotomy should give
good results.  The results of 259 pallidotomies were  95% (247) good or fair
and 5% (12) poor.  Looking at the side effects in the 259 pallidotomies, the
right pallidotomies had seven with scotomas in the visual field and one had
facial weakness; for the left pallidotomies there were four scotomas, one
foot apraxia, one dysphasia, one stroke seven days after surgery and
unrelated to the pallidotomy and one seizure.  Where both a left pallidotomy
and a left thalamotomy were performed there was one foot apraxia after the
pallidotomy.  Where both a right pallidotomy and a right thalamotomy were
performed there was one dysarthria after the thalamotomy.  (Apraxia is the
loss or impairment of the ability to perform a learned movement.  Dysphasia
is impairment of speech.  Dysarthria is articulation impairment caused by a
lesion affecting the tongue or speech muscles.)
Looking just at the surgeries in 1993, 93% (93) were good or fair and 7% (7)
were poor.  Side effects for right pallidotomy was one with facial weakness.
 For the left pallidotomy there were no side effects.  For the right
pallidotomy and right thalamotomy there was one with a foot apraxia and for
the left pallidotomy and left thalamotomy there was one with dysarthria after
the thalamotomy.  The scotoma problem has been corrected.
Of all my thalamotomy and pallidotomy surgeries in 33 years of performing
neurosurgery I have had two patients die.  In 1964, after a successful
thalamotomy, a women died from an unrelated stroke when she was leaving the
hospital.  The other was an 85 year old women in 1991 who was doing well
after surgery and was showing how she could now eat, when she died of cardiac
arrest.  To my knowledge 19 patients have died waiting for the surgery.  This
tells that the surgery is not very dangerous.  It is much more dangerous to
be at home.  The risk of the surgery should not be taken lightly.  People of
all ages tolerate the pallidotomy and thalamotomy well.
 
External Electric Stimulation
 
The slides show graphically how the probe passes through the putamen,
external globus pallidus and finally arrives in the lateral pallidum.
 Looking at the lateral part of the globus pallidus there is a position that
looks like a good location for placement of an electrical stimulator.  If
this shows to be good, lesions will not be made, instead an electrical
stimulator will be inserted and controlled outside of the brain.  This is
much like a pacemaker used for heart patients.  There are a number of studies
using externally controlled electrical stimulation for the thalamus.  The use
of this technology for the pallidotomy is very new.
 
Drug Reductions
 
Drug reductions are possible for many having the pallidotomy.  Drug
adjustment is usually necessary to reflect the reduction of rigidity,
bradykinesia, dyskinesia and other symptoms as a result of surgery.  Often
drug adjustments are much easier due to the reduction of symptoms.
 
Patient Testing
.
Patient testing both before and after surgery includes walking, color, mental
and finger dexterity testing.  All patients showed improvement after surgery.
 
Question and Answer
 
Q.  Why not do both sides at the same time?
A.  If we place a lesion poorly on one side it is possible to do more damage
by doing the same poor lesion on the other side.  If we do only one at a time
adjustments can be made individually and we can see the results of each
surgery.  I discourage those patients wanting to have a bilateral pallidotomy
because for the time being it may be too risky.
 
Q.  Can the brain find a new pathway around the lesion or partially heal the
pathway lesion after surgery?
A.  There is a small region around the lesion that is swollen from surgery.
 This heals over the next two months or so.  It is possible for the brain to
discover new pathways.
 
 
Regards,
Alan Bonander   ([log in to unmask]).