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For Release After 10:30 a.m. CST, Wednesday, Dec. 3, 1997

NONINVASIVE GAMMA KNIFE MAY REPLACE SURGERY

FOR MANY PATIENTS WITH PARKINSON'S DISEASE

CHICAGO -- A noninvasive radiosurgical technique may ultimately replace surgery for many patients with Parkinson's disease and other movement disorders whose symptoms cannot be controlled by medicine, according to results of a preliminary study presented here today during the 83rd Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA).

"Stereotactic radiosurgery shows promise as an alternative to surgery to relieve the uncontrolled movements that are characteristic of Parkinson's disease and other movement disorders," said David P. Friedman, M.D., Thomas Jefferson University Hospital, Philadelphia. The technique is performed with equipment called a gamma knife that uses magnetic resonance (MR) imaging to identify the radiosurgical target. The radiation destroys selected portions of the globus pallidus or the thalamus, structures deep within the brain that are responsible for the tremors and other involuntary movements that are characteristic of Parkinson's disease.

The surgical treatment for Parkinson's disease is to make a small hole in the skull and place a probe into the brain which heats and destroys the targeted tissue, according to Howard W. Goldman, M.D., Ph.D., professor and vice chair, department of neurosurgery. "Our study looked at the success with the gamma knife in patients who were too old or ill to undergo surgery," Dr. Goldman said. "We've had such success, we're now offering it as an alternative to other patients as well."

According to Dr. Goldman, as many as 50,000 patients in the United States could benefit from the technique each year. "Nearly everyone with Parkinson's disease eventually becomes refractory to pharmaceutical treatment or develops side effects to medication, usually after 5 to 8 years of treatment," he said.

In the study reported by Dr. Friedman, 12 patients were treated with the gamma knife. Seven patients showed marked improvement in their symptoms, 3 had moderate improvement and 2 showed mild improvement with follow-up of 3 months. "With radiosurgery, it takes approximately 6 to 8 weeks to begin to see the effect of the treatment, according to Dr. Friedman. The results at 3 months were comparable to those achieved with surgery, he said.

Thalamotomy -- destruction of tissue in the thalamus -- is used to control tremors. Pallidotomy -- destruction of tissue in the globus pallidus -- is used to control rigidity and larger involuntary movements, Dr. Friedman said.

The advantages of radiosurgical thalamotomy or pallidotomy with the gamma knife compared to conventional surgery, according to Dr. Friedman and Dr. Goldman are:

ï It is a noninvasive procedure without the risks of hemorrhage or infection that are associated with open surgery. "The only adverse effect seen with the gamma knife was late-onset swelling of brain tissue in 2 patients that largely resolved over time," Dr. Friedman said. Swelling also can be a side effect of conventional surgery, Dr. Goldman said.

ï Patients are hospitalized for only 24 hours compared to 3 or more days with surgery.

ï There is little or no recovery time. Recovery from surgery takes about 2 weeks. "The effects of the gamma knife occur gradually, so we typically don't see side effects such as weakness and confusion that sometimes occur immediately after surgery," Dr. Goldman said.

There are 90 gamma knife machines in use worldwide, 32 in the United States.

Co-author of a paper on the topic presented by Drs. Goldman and Friedman during the RSNA meeting is A. Flanders, M.D.

The RSNA is an association of 30,000 radiologists and physicists in medicine dedicated to education and research in the science of radiology. The Society's headquarters are located at 2021 Spring Road, Suite 600, Oak Brook, Illinois 60523-1860.

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Copies of 1997 RSNA news releases are available online at http://www.pcipr.com/rsna beginning Monday, Dec. 1.