Neuronavigation in transspenoidal surgery of pituitary adenomas

Abstract

BACKGROUNDThe outcome of patients with pituitary adenomas who were treated surgically with or without postoperative radiotherapy was analyzed. The purpose of this study was to determine the factors that strongly influence (A) tumor control, (B) the efficacy of surgery, and (C) radiotherapy based on the hormonal activity of adenomas and its invasion characteristics.METHODSBetween 1982–1996, 684 patients with the diagnosis of pituitary adenoma were operated on. The mean age was 38 years and the mean follow-up time was 40.5 months. A total of 516 patients who were followed for more than 1 year were studied to analyze the effect of treatment modalities and invasion characteristics on tumor control. There were 297 patients with prolactinomas, 118 patients with somatotropinomas, 45 with corticotropinomas, 17 with mixed adenomas, two with thyrotropinomas, and 205 with null cell adenomas. All patients were classified according to Hardy’s modified radiological classification scheme and analyzed in invasive and noninvasive groups individually based on this classification system. In the early postoperative period, 230 of these patients were given conventional radiotherapy with a mean dose of 4400 cGy. The following factors were analyzed for prognostic significance in tumor control: the effects of surgery and radiotherapy based on tumor types and invasion characteristics, the existence of histologically proven invasion of the dura mater overlying the sellar floor, and the early results of topical bromocriptine application in macroprolactinoma patients.RESULTSOverall surgical complications and mortality rate were similar to those of large series reported in the literature. Except for the invasive somatotropinomas and null cell adenomas, statistical analysis demonstrated the ineffectiveness of radiotherapy on tumor control. We did not detect any positive correlation between the recurrence rate and mean recurrence time or dural invasion of the sellar floor. Topical bromocriptine application seemed to improve tumor control in 21 selected macroprolactinoma patients.CONCLUSIONConventional radiotherapy is not as effective as expected, considering its adverse effects. The increased side effects of radiotherapy in cases with supra-parasellar extension, especially to the optic pathway and hypothalamus, limit its benefits, which could be demonstrated only in invasive somatotropinomas and null cell adenomas. In contrast with our current beliefs, tumoral infiltration of the sellar dura mater is not a prognostic factor for recurrence and therefore should not be a criterion for radiotherapy after surgery. Topical application of bromocriptine into the sellar cavity after tumor removal seems to provide superior results compared with the conventional treatment modalities.