Pituitary tumors and gamma knife surgery. Clinical experience with more than two years of follow-up.

30 patients with pituitary tumors were treated in our unit and followed for 26-45 months. 14 patients had nonsecreting adenomas, 7 had acromegaly, 5 had prolactinomas, 3 had Cushing's disease. One patient had a choristoma of the pituitary stalk. The patient with a choristoma, 7 patients with nonsecreting adenomas, 4 with acromegaly, 1 prolactinoma and 3 with Cushing's disease had been operated by transsphenoidal microsurgery prior to Gamma Knife (GK) treatment. From this group, one patient with a nonsecreting adenoma and two with acromegaly had undergone fractional external radiotherapy after surgery. Stereotactic MRI localization had been used in all cases. All the tumors showed either a reduction in volume or cessation of growth; 85% of the patients with acromegaly showed normalization of growth hormone (GH) levels. Normalization of ACTH levels occurred in the 3 patients with Cushing's disease. All the patients with prolactinomas showed reduction of prolactin levels but normalization did not occur. However, in 3 cases the bromocriptine could be withdrawn. Deterioration of vision was not observed. One patient suffered transient paresis of the third cranial nerve that improved with steroids. Panhypopituitarism appeared in one case of Cushing's disease two years after the treatment. In the remaining cases there were no changes in their previous physiological pituitary function. We conclude that GK radiosurgery in pituitary tumors is an effective alternative to transsphenoidal microsurgery when compression of surrounding structures does not exist, and it can efficiently replace conventional irradiation.