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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]).