Use of the radiosurgery knife in the treatment of hypophyseal adenomas

: BACKGROUND. Surgery of pituitary adenomas did not produce quite satisfactory results. Therefore radiosurgery using Leksell's gamma knife has become the most widely used method which-with the contribution of MRI-meets the most important demands of aimed irradiation: a sufficiently high dose of radiation of the tumour and minimal radiation load of functionally important surrounding structures. The objective of the investigation was to assemble experience with this therapeutic method. METHODS AND RESULTS. During the period between October 1992 and September 1994 a total of 41 patients were treated: 16 men, 12-66 years old, mean age 40.8 years; 25 women age 16-76 years, mean age 50.2 years. Female:male ratio 1.5 : 1. In 30 patients (73.2%) a microsurgical operation had preceded, in 5 (12.2%) conventional fractionated radiotherapy and in 11 patients (26.9%) primary radiosurgery. As far as the type of pituitary adenoma is concerned, it conditioned acromegaly in 30, Cushing's syndrome in 3 or Nelson's syndrome in 1, or a prolactinoma was involved (in 2 patients). In five instances the adenoma was hormonally inactive. Its localization was most frequently intrasellar (36), less frequently parasellar (5). The range of administered doses varied as regards the maximum between 12.5 and 80 Gy, the average being 46.8 Gy, to the periphery of the adenoma a dose of 10-49 Gy was administered, on average 24.7 Gy using a 50-80% isodose. The time interval after treatment is relatively short for detailed analysis or evaluation. During current evaluation the authors did not observe in any of the patients progression of the disease, and in several patients diminution of the tumour was found. Karnofski's score seemed to improve. CONCLUSIONS. Radiosurgery, using Leksell's gamma knife, is after failure of conservative and microsurgical therapeutic possibilities suitable further treatment of pituitary adenoma. In indicated cases it may be the first choice. Postirradiation follow up indicates promising effects, for more detailed evaluation a several years' interval is necessary.