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RSNA MEETING: Noninvasive Gamma Knife May Replace Surgery For Many Patients With Parkinson's CHICAGO, IL -- December 3, 1997 -- 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 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 Friedman, M.D. of Philadelphia's Thomas Jefferson University Hospital. 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 five to eight 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, three had moderate improvement and two showed mild improvement with follow-up of three months. "With radiosurgery, it takes approximately six to eight weeks to begin to see the effect of the treatment, according to Dr. Friedman. The results at three 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: -- 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 two patients that largely resolved over time," Dr. Friedman said. Swelling also can be a side effect of conventional surgery, Dr. Goldman said. -- Patients are hospitalized for only 24 hours compared to three or more days with surgery. -- There is little or no recovery time. Recovery from surgery takes about two 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.