Dec. 5, 1997 Researchers at Jefferson Medical College of Thomas Jefferson University and Wills Eye Hospital, Philadelphia, are sidestepping surgery and using a device to deliver high doses of tissue-destroying radiation to tiny targets deep within the brain in the hopes of alleviating the symptoms of Parkinson’s disease. Doctors hope that the noninvasive gamma knife will offer both reduced recovery time and shorter hospital stays for patients with Parkinson’s and other movement disorders whose symptoms cannot be controlled with medication.
At the 83rd Scientific Assembly and Annual Meeting of the Radiological Society of North America in Chicago, David P. Friedman, M.D., associate professor of radiology, Jefferson Medical College, reports results on December 3 of the first 12 Parkinson’s disease patients to undergo gamma knife treatment. Of those treated, seven showed marked improvement in their symptoms, three had moderate improvement and two showed mild improvement with a three-month follow-up. Dr. Friedman notes that such results are comparable to those of surgery. The patients in the study all were unable for various reasons to undergo conventional surgery.
The gamma knife uses magnetic resonance imaging to identify the radiosurgical target. The radiation destroys certain areas of the brain’s thalamus or globus pallidus, hoping to control tremors, rigidity or other involuntary movements.
According to H. Warren Goldman, M.D., Ph.D., professor and vice-chair, neurosurgery, Jefferson Medical College, and at Wills Eye Hospital, Philadelphia, as many as 50,000 patients a year could benefit from the treatment. Dr. Goldman, who notes "this is a relatively new use of the gamma knife," says that doctors are so pleased with the technique’s results to date that they have begun offering the treatment as an alternative to other patients as well.
Nearly all patients with Parkinson’s eventually, within five to eight years, become refractory to treatment by medicine. When medication fails, doctors may treat Parkinson’s by two types of brain surgery. In a thalidotomy, surgeons remove or destroy tissue in thalamus, which controls tremors. In a pallidotomy, tissue in the globus pallidus is destroyed in an attempt to control rigidity and some involuntary movements.
The gamma knife has several advantages over surgery, according to Drs. Goldman and Friedman. The treatment is noninvasive, without the risks of bleeding or infection. Patients remain hospitalized for only 24 hours compared to three or more days with surgery. Recovery time from gamma knife treatment is minimal; recovery from surgery typically takes at least two weeks.
The treatment has some downsides, however. Whereas surgery results are almost immediate, gamma knife treatment results take time, and may not be known for perhaps as long as six or eight weeks.
The gamma knife is primarily used to treat brain tumors and various vascular malformations. "This expands its uses," Dr. Friedman says. "Though some 90 centers worldwide, including 32 centers in the United States, have the gamma knife, only perhaps a handful use them this way." Jefferson and Wills began using the gamma knife to treat Parkinson’s in July 1996. Dr. Goldman believes that it is the only such device in the Philadelphia area.
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