The benefits of pallidotomy, which improves motor function in patients with Parkinson’s disease, last for at least three years after surgery, a team of Emory University neurologists has found. And, unexpectedly, both sides of the body show this persistent improvement.
“This has not been seen before,” said Jerrold Vitek, M.D., Ph.D., director of functional neurology and associate professor of neurology at the Emory University School of Medicine. “We’ve really been surprised — it’s a nice observation.”
Previous studies have shown that pallidotomy surgery performed on one side of the brain did not have a sustained effect on parkinsonian motor symptoms on both sides of the body.
Dr. Vitek will present the study Friday, May 5, 2000 at the American Academy of Neurology’s 52nd Annual Meeting in San Diego.
In the study, 20 patients with Parkinson’s disease who underwent pallidotomy were assessed before and after surgery using the Unified Parkinson’s Disease Rating Scale and timed tests of motor function. The patients were reassessed at six and 12 months after surgery, and every year thereafter.
Following the procedure, the patients showed significant improvement in their UPDRS and motor scores. This improvement has persisted through the 36-month follow-up.
The study confirms that pallidotomy is an effective long-term treatment for parkinsonian motor signs such as tremor, rigidity and slowness. While the short-term effectiveness of pallidotomy has been well documented, only a few studies have reported long-term effects.
However, none of the studies that looked at long-term outcomes reported persistent motor function improvement in both sides of the body. Instead, previous research had found that when pallidotomy surgery was performed on one side of the brain, motor control on the same side of the body improved only temporarily, no longer than six months.
This made sense, since each side of the brain controls motor function on the opposite side of the body. If surgery was performed on the right side of the brain, the body’s left side would be primarily affected, and vice versa.
Now, the Emory study raises interesting questions about pallidotomy’s effects.
“This is not to say that these patients won’t at some time need a second procedure on the other side of the brain,” Dr. Vitek said.
In pallidotomy, physicians destroy a portion of the internal segment of the globus pallidus, a part of the brain involved in motor control. It isn’t known what role the globus pallidus plays in the brains of normal people; but removing it can reduce the trembling and other movement symptoms that are the hallmark of Parkinson’s disease.
As mentioned, performing pallidotomy on one side of the brain has tended to only temporarily affect the same side of the body, termed the ipsilateral side. Thus, many people with Parkinson’s may need a second procedure to correct worsening parkinsonian signs on the ipsilateral side. But performing pallidotomy on both sides of the brain often results in a complication called hypophonia, meaning “quiet speech.” A better option for people who have undergone pallidotomy is to perform a non-lesioning procedure, such as deep brain stimulation, on the other side of the brain.
Emory University has played a significant role in developing pallidotomy surgery. Mahlon DeLong, M.D., chair of the neurology department, neurosurgeon Roy A.E. Bakay, M.D. and Dr. Vitek helped develop the methods for microelectrode mapping of the pallidus that are necessary for performing pallidotomy surgery.
The study was funded by a grant from the National Institutes of Health to Dr. DeLong and his colleagues, Drs. Vitek and Bakay.