 |
 |
I found this on the CBC Home Page (Health Show). Pallidotomy and Deep Brain Stimulation Original Airdate: Thursday, November 23, 1995 Deep Brain Stimulation Update: Tuesday, March 10, 1998 Reporter: Linda McEwan 100,000 Canadian suffer from Parkinson’s Disease. It affects cells in the middle of the brain where the brain makes the transmitter Dopamine, a chemical that allows nerve cells to talk to each other. Parkinson’s stops the production of Dopamine. They don’t know what causes the disease, they do know the drug L-dopa, which mimics dopamine, is an extremely effective substitute. Without it patients would be completely rigid. But after years of use, L-dopa has powerful side-effects: wild movements and uncontrollable shakes. This is why many Parkinson’s sufferers have to take more drugs, to smooth out the side-effects of L-dopa. But the results are not lasting, so neurologists are trying something new; actually, it’s an updated version of an old procedure, an operation called a pallidotomy. Pallidotomies were first performed in the 1950’s. Doctors knew that Parkinson’s sufferers had some brain cells that were overactive, the idea was to find those cells and destroy them by burning them. But back then, it was a pretty crude operation; surgeons found their target by trial and error, burning until they found the spot that worked. Today, technology and a better understanding of the brain has improved the odds. A pallidotomy is essentially a search and destroy mission, and the search for those hyperactive cells takes the longest time. The first step is to bolt onto the head a frame. An MRI records images of the brain and calculations are made to give the surgeon a general target area. The patient remains awake to help the surgeon find the specific cells. A hole is drilled in the skull and using a probe called a micro-electrode, the surgeons map the brain. The brain has no pain receptors so the patient won't feel anything. As the surgeon moves the probe towards the target area, it records the activity of individual nerve cells. Neurons make distinctive sounds. By listening, the surgeon can tell what type of neuron it is and where it is in the brain. They’re looking for a target about the size of a small pea. Since the probe moves only a few millimetres at a time, it takes hours to map the brain. Everyone’s brain is a slightly different size, and the function of different structures within the brain is slightly different from patient to patient. That’s why you can’t apply a general formula and a general recipe. Once the search is complete, the surgeon has the exact location of those overactive cells. Using another probe, he’ll now destroy them with a tiny electrical current. This part of the operation takes only minutes. Recently another procedure has been developed for Parkinson patients called deep brain stimulation. It's much safer and more practical. It's exactly the same as a pallidotomy except instead of destroying the over-active cells, they're hooked up to a permanent electrode. The electrodes are inserted into the brain and then tunneled underneath the skin in the scalp behind the ear. They run down underneath the skin of the neck to the chest and are hooked up to a pulse generating device - a pacemaker. An electrical current runs through the electrodes and blocks the activity in the cells, paralyzing them and stopping the tremors. Deep brain stimulation can be used for people whose Parkinson's affects both sides of the brain. A pallidotomy can only be performed on one side of the brain. (note: I know of people who have had pallidotomies on both sides of the brain). The stimulation can be turned off or down as the disease progresses and the symptoms change. So far the only downside to the procedure is patients have to carry battery packs under their skin which could break or malfunction and of course the batteries need to be replaced every two to three years. These patients still have Parkinson's disease. They are not cured. They still require medications. Updated On March 12, 1998 Copyright © CBC All Rights Reserved. Judith Richards [log in to unmask]