Surgery may be used to control symptoms of Parkinson's disease and improve the quality of life when medication ceases to be effective or when medication side effects, such as jerking and dyskinesias, become intolerable.Not every Parkinson's patient is a good candidate for surgery. For example, if a patient never responded to, or responded poorly to levodopa/carbidopa, surgery may not be effective. Only about 10% of Parkinson's patients are estimated to be suitable candidates for surgery.
Every surgical procedure carries inherent risks. Parkinson's patients who are suitable for surgery may forgo the procedure if they feel these risks outweigh the potential benefits. In some cases, Parkinson's symptoms do not improve or worsen following the operation.
There are three surgical procedures for treating Parkinson's disease: ablative surgery, stimulation surgery or deep brain stimulation (DBS), and transplantation or restorative surgery.
Ablative Surgery
This procedure locates, targets, and then destroys (ablates) a clearly-defined area of the brain affected by Parkinson's disease. The goal of this surgery is to destroy tissue that produces abnormal chemical or electrical impulses that result in tremors and dyskinesias.
In ablative surgery, a heated probe or electrode is inserted into the targeted area. During the procedure, it may be difficult to determine how much tissue to destroy and the amount of heat to use. It is safer to treat a small area and risk the tremor returning or not being eliminated, than to treat a larger region and risk serious complications, such as paralysis or stroke.
Types of ablative surgery include pallidotomy or thalamotomy. Pallidotomy—ablation in the part of the brain called the globus pallidus—involves putting a hole (i.e., otomy) in the globe-shaped structure located deep inside the brain. This procedure is performed to eliminate uncontrolled dyskinesias. Thalamotomy—ablation of brain tissue in the thalamus—involves creating an otomy in the structure located below the globus pallidus. The procedure is performed to eliminate tremors. A related procedure, called cryothalamotomy, uses a supercooled probe that is inserted into the thalamus to freeze and destroy areas that produce tremors.
The patient remains awake during these procedures to determinine if the tremor or dyskinesia has been eliminated. A local anesthetic is used to dull the outer part of the brain and skull. The brain is insensitive to pain, so it can be manipulated and probed without causing pain.
Deep Brain Stimulation (DBS)
Deep brain stimulation targets the subthalamic nucleus, which is located below the thalamus. In DBS, the targeted region is inactivated, not destroyed, by an implanted electrode. The electrode is connected via a wire running beneath the skin to a stimulator and battery pack in the patient's chest. This procedure is reversible—just turn off the current—and allows for precise calibrated symptom control.
DBS does carry some risks. The electrode can become infected, the simulator may have to be periodically programmed, the battery must be replaced every 5 years, and the wires may break and need replacing. Battery replacement involves minor surgery.
Transplantation or Restorative Surgery
These procedures are still considered experimental for Parkinson's disease. In transplantation, or restorative, surgery dopamine-producing cells are implanted into the striatum. The cells used for transplantation may come from one of several sources: the patient's body, human embryos, or pig embryos.
Using cells from the patient's body has been unsuccessful because of an insufficient supply of dopamine cells and the inability of the implanted cells to survive. To use fetal cells, between three and eight embryos are needed per procedure, and even under the most favorable conditions, 90% of transplanted cells do not survive. This procedure is only moderately effective in some patients and usually in those younger than age 60. Preliminary studies have shown that pig embryo cells do survive transplantation and have an effect on symptoms.
Stem cells, which are primitive cells that can grow into nerve cells, are able to survive and reproduce. Once they grow as nerve cells, they can be transformed into dopamine-producing cells. Stem cells are obtained from discarded blood in a newborn's umbilical cord, from the bone marrow of an adult, or from an aborted embryo.
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Original Date of Publication: 02 Jan 2000
Reviewed by: Gordon R. Kelley, M.D., Stanley J. Swierzewski, III, M.D.
Last Reviewed: 03 Sep 2008
Parkinson's Disease, Surgery reprinted with permission from neurologychannel.com
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