Endonasal Approach for Giant Pituitary Adenoma: A Single Surgeon’s Experience of 60 Cases

Introduction: Giant pituitary adenomas (GPA) are defined as tumors > 40 mm in diameter and account for 5 to 14% of all pituitary adenomas. Despite advances in field of microsurgery, these adenomas still pose great therapeutic challenge. An endoscopic endonasal approach is less invasive and increases the extent of resection. In this study, we analyzed our surgical results for 60 cases of giant pituitary adenomas operated by microscopic or endoscopic endonasal approach and estimated the efficacy and complications in terms of tumor extension and type, and discuss the advantages and limitations of this technique.

Methods: This study is a retrospective analysis of 60 patients with pituitary adenomas > 40 mm treated by microscopic or endoscopic endonasal trans-sphenoidal surgery (TSS) between 2009 and 2018. Neurological, visual, endocrinological and surgical outcome were analyzed.

Results: Males comprised 73.3% of study population with mean age at presentation being 41.5 years. 53% patients presented after 1 year of onset of symptoms. The most frequent presentation was visual decline (57 = 95%) and headache (36, 60%). Nonfunctional tumors were the most commonly encountered (45, 75%) followed by GH-secreting tumors (10, 16.7%), prolactinomas (4, 6.7%), and ACTH-secreting tumors (1, 1.7%). The tumor volume was < 25 cc in 25%, 25–29 cc in 51.6%, >50 cc in 23.3% patients. Multicompartmental extensions were present in 35 (58.3%) patients; Knosp grades 3 and 4 in 19 (31.7%) patients. Microscopic endonasal surgery was performed in 12 (20%), endoscopic endonasal surgery in 47 (78.3%) and combined endoscopic endonasal and transcranial surgery in 1 patient. Gross-total and near-total excision was achieved in 36 cases (60%); 7/12 (58.3%) in microscopic TSS and 29/47 (61.7%). Visual acuity or fields improved in 40 (66.7%), stable in 16 (26.7%) and worsened in 4 (6.7%). The extent of resection was significantly related to retrosellar, subfrontal, cavernous sinus extensions, multilobulated tumor and T2WI hypointensity on MRI imaging. Postoperative complications included diabetes insipidus which was transient in 14 (23.3%) and chronic in 2 (3.3%) and apoplexy in 11 (18.3%). There were four mortalities related to postoperative apoplexy in residual tumor and multiple comorbidities.

Conclusion: Microscopic or endoscopic endonasal TSS enables less invasive and safer removal of various extension types of giant pituitary adenomas with complications and results comparable to other transcranial and transsphenoidal approaches. Early visual improvement occurs due to adequate decompression of optic apparatus.