Endoscopic Endonasal Approach as the Primary Surgical Management of Giant Pituitary Adenomas

Object: Giant pituitary adenomas (> 4 cm in maximum diameter) represent a significant surgical challenge. At our center the endoscopic endonasal approach (EEA) has been utilized for the management of these tumors. We present the results of EEA as the primary treatment option for giant pituitary adenomas. The advantages and limitations of this technique are analyzed.

Methods: We retrospectively reviewed the medical records and imaging studies of 50 patients with giant pituitary adenomas who underwent EEA from 2008 to 2015. The factors affecting the extent of resection and clinical outcomes were evaluated.

Results: The mean age was 55.1 (+/−13.3) years, with a male predominance (64%). Visual impairment was present preoperatively in 44 patients (88%). Preoperative endocrine evaluation revealed partial pituitary deficiency in 15 patients (30%), pan-hypopituitarism in 10 patients (20%), and hormone over-secretion in four patients (two with growth hormone, one with adrenocorticotrophic hormone (ACTH) and one with prolactin secretion).

Post-operative vision was improved or normalized in 28 patients (65%), stable in 14 (33%), and worsened in one case. Recovery of pituitary deficiency occurred in six patients (24%) and a new hormonal deficit of one or more hypothalamic pituitary-axis occurred in seven patients (17%). All four patients with hormone secreting adenomas had a chemical cure with surgical resection followed by adjuvant therapy. Complications included apoplexy of the residual tumor in one case which resulted in an ischemic stroke. Cerebrospinal fluid leaks occurred in two patients, both of which underwent a successful endoscopic repair. Permanent diabetes insipidus (DI) occurred in two patients.

Gross total resection was achieved in 23 patients (46%) and near total resection in 15 patients (30%). Significant factors that limited the degree of resection were a multi-lobular configuration of the adenoma (p = 0.001), and extension into the middle (p = 0.001) and posterior fossa (p = 0.003). Tumor size (p = 0.16), cavernous sinus invasion (p = 0.32) intraventricular (p = 0.69), and anterior fossa extension (p = 0.10) did not negatively affect the degree of surgical resection. Nine patients underwent adjuvant radiation therapy after tumor resection for tumor and chemical control. In a mean follow-up period of 33 (+/−22) months, tumor recurrence or progression occurred in four patients. Of the recurrent cases, one patient underwent reoperation followed by fractionated stereotactic radiotherapy (FSRT), one was treated with FSRT alone, and the remaining two patients were kept under close observation without the need for further treatment.

Conclusion: The EEA is an excellent option for the primary management of giant pituitary adenomas. It results in surgical and clinical outcomes which are superior to the traditional microscopic transsphenoidal and transcranial approaches reported in the literature.