Endoscopic Endonasal Approach for Giant Pituitary Adenomas: Advantages and Limitations

Introduction: Giant pituitary adenomas (measuring more than 4 cm in maximum diameter) are associated with high rates of residual tumor regardless of the surgical approach. We present the results of the endoscopic endonasal approach (EEA) and analyze the factors that influence the degree of resection.

Methods: We retrospectively reviewed the medical files and imaging studies of 54 patients (85% men) with giant pituitary adenomas who were managed with EEA.

Results: The maximum tumor diameter varied from 40 to 90 mm (mean, 50 mm). Nonfunctioning pituitary adenomas represented 74% of the cases. Preoperative visual impairment was present in 45 patients (83%), partial or complete pituitary deficiency occurred in 28 cases (52%), and 7 patients (13%) presented with apoplexy. Gross total or near total (>90%) tumor resection was obtained in 36 patients (66.7%). Vision was improved or even normalized in 36 cases (80%), remained unchanged in 6 (13%), and deteriorated (due to apoplexy of residual mass) in 2. Pituitary function remained unchanged in 44 patients (81.5%); new pituitary insufficiency occurred in 9 patients (16.7%). Significant factors that limited the degree of resection were a multilobular configuration of the adenoma (P = 0.002), extension to the middle fossa (P = 0.048), and previous treatment (surgical or medical) (P = 0.047). Size, intraventricular extension, and invasion of the cavernous sinus did not influence the surgical outcome. Apoplexy at presentation was associated with higher rates of resection. Complications included apoplexy of residual adenoma in two cases (3.7%), permanent diabetes insipidus in five (9%), transient cranial nerve palsies in six (11%), and cerebrospinal fluid leak in 9 (16.7%). After EEA, 13 patients underwent radiotherapy for residual mass, and 4 with functional pituitary adenomas received medical treatment. During a mean follow-up of 29.3 months (range, 1–109 months), seven patients were reoperated for tumor recurrence.

Conclusions: The main goals of surgery for giant pituitary adenomas are decompression of the optic pathway and maximum safe tumor reduction. EEA provides effective initial treatment of giant pituitary adenomas with fewer limitations compared with the traditional transsphenoidal or open approaches. Despite the satisfactory results with tumor reduction, the high incidence of residual mass frequently requires the use of adjuvant therapies.