symptoms of parkinsons disease : Surgery

Surgery is another method of controlling symptoms and improving quality of life when medication ceases to be effective or when medication side effects, such as jerking and dyskinesias, become intolerable.
Not everyone is a good candidate for surgery. For example, if a patient never responded to, or responded poorly to levodopa/carbidopa, surgery may not be of any help. Only about 10% of Parkinson's patients are estimated to be suitable candidates.

Those who are suitable but forgo surgery may feel the risk outweighs the benefit. Every surgical procedure carries inherent risk. Additionally, there is the risk that symptoms will not improve or will 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. The object is to destroy tissue that produces abnormal chemical or electrical impulses that produce tremors and dyskinesias.

A heated probe or electrode is inserted into the targeted area. It is often difficult to estimate how much tissue to destroy and the amount of heat to use. It is always safer to burn a small area and risk the tremor returning or not being eliminated, rather than burning a larger region and risking serious complications such as paralysis or stroke.

The patient remains awake during this procedure 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 the patient feeling it.

This type of surgery involves either pallidotomy or thalamotomy. Pallidotomy—ablation in the part of the brain called the globus pallidus—involves putting a hole (i.e., otomy) in the globus pallidus, 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 thalamus. This structure is located below the globus pallidus. The procedure is performed to eliminate tremors.

A related procedure, cryothalamotomy, uses a supercooled probe that is inserted into the thalamus to freeze and destroy areas that produce tremors.

Deep Brain Stimulation (DBS)
DBS targets the subthalamic nucleus, which is located below the thalamus and is difficult to reach, the globus pallidus, or 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. It is reversible—just turn off the current—and allows for precise calibrated symptom control.

The risk for hemorrhage or stroke is reduced, but the electrode can become infected, the simulator may have to be periodically programmed, and the battery must be replaced every 5 years. Battery replacement involves minor surgery.

Transplantation or Restorative Surgery
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, 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, 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, the bone marrow of an adult, or an aborted embryo.

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