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By Bill Snyder / Staff Writer
Harry Thomas says he is no longer a prisoner in his own body, thanks to innovative brain surgery for Parkinson's disease he underwent earlier this year at Vanderbilt University Medical Center. "I'm doing a whole lot better," said the 52-year-old Nolensville man, the first of six Vanderbilt patients who have completed the two-stage procedure since March. "I still have some good days and some bad days, but there are a lot more good days than there are bad." The operation, developed in France, involves implanting small electrodes in a structure deep in the brain to squelch major symptoms of the neurological disease, particularly muscle rigidity and tremors. Vanderbilt is one of a few medical centers nationwide offering this new form of "deep-brain stimulation." |
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Harry Thomas checks functioning of his brain implants. (Delores Delvin / Staff) |
"I'm doing a whole lot better," said the 52-year-old Nolensville man, the first of six Vanderbilt patients who have completed the two-stage procedure since March. "I still have some good days and some bad days, but there are a lot more good days than there are bad." |
The operation, developed in France, involves implanting small electrodes in a structure deep in the brain to squelch major symptoms of the neurological disease, particularly muscle rigidity and tremors.
Vanderbilt is one of a few medical centers nationwide offering this new form of "deep-brain stimulation."
With four other institutions, Vanderbilt also is applying for a major research grant to study whether the technique can slow or even stop the progressive loss of muscle control experienced by many Parkinson's disease patients, despite medical treatment.
"This whole concept of (stopping) disease with stimulation is brand new and very exciting," said Vanderbilt neurosurgeon Dr. Peter E. Konrad. "It might be the first device that can actually alter the course of a disease, rather than just treat the symptoms."
About 1 million Americans -- including Attorney General Janet Reno and evangelist Billy Graham -- suffer from Parkinson's disease.
The neurological disease is characterized by trembling in the hands, arms, legs and face, stiffness of the limbs and trunk, a shuffling walk, and difficulty keeping one's balance.
It is caused by the death of cells in the substantia nigra, a structure in the center of the brain. These cells normally produce dopamine, a chemical messenger essential for normal brain activity.
When dopamine levels drop, other parts of the brain responsible for movement "rev up" in an uncoordinated and out-of-control manner, Konrad explained.
Levodopa, which is converted into dopamine in the body, revolutionized the treatment of Parkinson's disease when it was introduced in the 1960s. By restoring the brain's supply of dopamine, the drug can dramatically reduce tremors and other symptoms.
But levodopa can cause side effects, including agitation and hallucinations. It also can cause the pendulum to swing too far in the other direction, producing wild, involuntary movements of the arms and legs, called dyskinesia.
Over time, the drug's effects may wax and wane, leaving the patient flailing uncontrollably one moment and "frozen" with clenched muscles the next.
Frozen in place
Last year, Harry Thomas was losing hope. The medicine he'd taken for 10 years to control tremors and muscle rigidity caused by the degenerative nerve disease was losing its effectiveness.
Sometimes he appeared to be frozen in place, unable to move his legs because his muscles were clenched as tight as a fist. At other times, the drug worked too well, causing wild, involuntary thrashings of his arms and legs.
Thomas had to sell his auto repair shop because the symptoms were so bad. He couldn't go fishing or drive more than short distances. And when his 6-foot, 186-pound frame was "frozen," his 27-year-old son Bill had to pick him up and take him where he needed to go.
"I've seen Bill carry him across the yard several times and get him in the car," recalled Thomas' wife, Melissa.
Thomas feared he would become increasingly reclusive and dependent on family members as his disease progressed. Then he heard about deep-brain stimulation.
For the past several years, doctors have used deep-brain stimulation in various parts of the brain to relieve severe tremors and other symptoms of Parkinson's disease.
Recently, doctors at the University of Grenoble in France found that when they stimulated a new area, the subthalamic nucleus, they could relieve muscle rigidity as well and substantially reduce patients' reliance on medication.
Dr. David Charles, a neurologist who directs the Vanderbilt Movement Disorders Clinic, worked with the Grenoble team in late 1998 and brought the procedure to Vanderbilt.
Located below the thalamus, the pea-sized subthalamic nucleus seems to act like a "governor," regulating the activity of other parts of the brain involved in movement.
When the subthalamic nucleus is starved for dopamine, as is the case in Parkinson's disease, "it starts running wild," Konrad said. The result: Muscle tone rises so high that patients can't move.
Deep-brain stimulation can bring the subthalamic nucleus back to its normal idling speed, he said, possibly by fatiguing the overactive cells.
Computer guidance
Because it requires surgery to implant the electrodes, deep-brain stimulation can cause serious complications, including infection and stroke, if a blood vessel in the brain is nicked during the operation.
About four years ago, a Vanderbilt patient died from bleeding in the brain after an electrode was implanted in the thalamus to relieve severe tremors.
"The risk is very real," Charles said.
But the risk of serious complications has been reduced, thanks to computer-guided navigation systems that can take surgeons to precise targets without damaging surrounding tissue, he added.
The Vanderbilt doctors implant an electrode in the subthalamic nucleus on each side of the brain in two separate procedures. That's because of the lengthy, tedious nature of each operation, which can last six hours or longer.
Last month, Mike Rodriguez, a 75-year-old Fayetteville man with steadily worsening muscle rigidity and dyskinesia, received his second electrode, on the right side of his brain, to relieve symptoms on the left side of his body.
First, to guide their efforts, surgeons screwed a lightweight metal frame, under local anesthesia, around his head. They took a CAT scan to generate a three-dimensional map of internal brain structures and used computers to plot the path of the electrode.
The surgical guidance system is similar in concept to the "global positioning device" used in cars to help drivers navigate through unfamiliar territory.
Next, the surgeons cut a hole in Rodriguez's skull and inserted a recording electrode into his brain. The electrical firings of his brain cells were translated into "brain waves," squiggly lines on a graph, and into sounds the surgeons could hear.
As the electrode was pushed deeper into the brain, it recorded an occasional sputtering of brain activity. But when it reached the overactive subthalamic nucleus, the speaker crackled like an old-fashioned radio.
"That isn't just noise," Konrad explained. "What you heard was the sound of Parkinson's disease."
Once the target was reached, the recording electrode was pulled out and replaced with another thin wire that transmits high-frequency electrical current.
Rodriguez stayed awake during the entire procedure so doctors could determine exactly where to place the electrode -- and how much voltage to send through it -- for the greatest benefit and fewest side effects.
Lasting effect
The operation isn't painful, Konrad said, because the brain cannot feel pain.
Meanwhile, Charles wiggled Rodriguez's upraised left arm to test his muscle tone and watched for any undesirable side effects, including vision and memory problems.
Minutes later, the target had been located.
"This has really just loosened up," Charles said, shaking his patient's arm. "If we hit the right spot, that rigidity will just melt away."
Now surgeons had to connect the electrode to its power source.
A connecting wire was threaded under the skin of Rodriguez's scalp, behind the ear and down to the chest, where it was attached to a small generator placed under the skin below the collarbone.
When activated by passing a magnet over it, the generator, which works much like a heart pacemaker, sends its current into the brain to squelch abnormally active nerve cells.
Rodriguez, who had remained patient and placid throughout the 10-hour procedure, couldn't contain himself anymore, and began to sing, "Please release me, let me go," to the delight of the surgical team.
After spending a night in the intensive-care unit, he was able to go home. But his relief from symptoms was not immediate or automatic -- he must make several visits to Vanderbilt to have his medication and voltage levels "fine-tuned."
Nevertheless, his wife, Joy, said she was very excited and hopeful.
"The thought that his life might be improved just slightly makes it worth the many years we have waited for this opportunity," added his daughter, Lisa Grubbs, of Nashville.
Harry Thomas says his electrodes, which were implanted in January and March, are "working great so far."
He hasn't been fishing yet, but he's been able to resume another favorite pastime -- tuning up the engines of racing cars.
"I'm tickled to death," he said.
His wife, Melissa, has more practical pursuits in mind.
"I've got a 'honey-do' list you just would not believe," she said.
Bill Snyder covers health care for The Tennessean. He can be reached
at (615) 259-8226 or bsnyder@tennessean.com.
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