adenoma The goal of pituitary adenoma radiosurgery is to halt tumor growth, to normalize hormonal hypersecretion if present, and to maintain the performance of a normal hypophysis and functionally important structures around the sella, namely the optic nerve. The minimum distance required between the irradiated target and the optic pathway should be reassessed. For Gamma knife model B (or C) the limit should be 2 mm for secreting adenomas and, in the case of non-secreting adenomas, direct contact of the adenoma with the optic chiasm may be tolerated where only a short segment is affected of the visual pathway. During the midterm of the follow up period, an anti-proliferative effect was achieved in all 305 evaluated patients and 70% of adenomas decreased in size usually within 2 years following radiosurgery. Hormonal normalisation of hypersecreting adenomas is comparable with the results of transsphenodial microsurgery, apart from the latency, which is usually 2 years.During this period hypersecretion was arrested in 38 % of patients with acromegaly, in 90% with Cushing’s disease and in 54% with prolactinoma. The most important factor influencing post-irradiation hypopituitarism seems to be the mean dose applied to the hypophysis. The current position of radiosurgery in the majority of cases is as an adjuvant treatment for residual or recurrent adenomas after previous microsurgery. In selected cases radiosurgery may be used as a primary treatment, e.g. in patients with contraindications of overall anaesthesia in patients, where the treatment effect is not urgent in the patients who refuse to undergo open surgery.

        Key words: pituitary adenoma - radiosurgery - gamma knife.