Introduction: Pituitary adenomas with subarachnoid invasion are challenging tumors with high morbidity related to their close association with critical neurovascular structures. Appropriate surgical approach selection and microsurgical technique are necessary to avoid iatrogenic injury. Previously, we developed a predictive score for identification of subarachnoid invasion (NETS score). In this study, we evaluate the utility of the NETS score for surgical approach selection and prognostication.
Methods: Data from 436 pituitary adenomas undergoing surgical intervention from 2018-2024 were collected. Subarachnoid invasion was identified intraoperatively in 35 cases. The NETS score for prediction of subarachnoid invasion including nodular tumor invasion (2 points), subarachnoid vessel encasement (2 points), tumor diameter > 20mm (1 point), and history of surgical intervention (1 point) was calculated for each case and stratified across surgical approach, extent of resection, and outcomes.
Results: Pituitary adenomas with subarachnoid invasion were managed with endoscopic endonasal approaches (EEAs, 80%), combined EEA/open transcranial approaches (14%), and purely open transcranial approaches (6%). Adenomas undergoing combined EEA/open transcranial approaches (p=0.01) or purely open transcranial approaches (p=0.08) were associated with higher NETS scores compared to adenomas treated with an EEA. Regarding extent of resection, significantly elevated NETS scores were observed in adenomas achieving subtotal resection compared to gross total resection (p=0.01). Adenomas requiring additional post-operative interventions also demonstrated higher NETS scores compared to tumors without need for additional treatment (p < 0.001). Specifically, higher NETS scores were identified in patients requiring additional surgical intervention (p < 0.01), cerebrospinal fluid diversion (p=0.04), and unplanned return to the operating room (p=0.02).
Conclusion : Nodular tumor invasion, subarachnoid vessel encasement, and tumor size affect surgical approach selection for subarachnoid adenomas. Lesions with elevated NETS scores (5-6) are at greater risk of subtotal resection and need for additional post-operative intervention and require consideration of combined EEA/open transcranial or purely open transcranial approaches to maximize safe resection.
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