Outcomes of intraoperative ultrasound for endoscopic endonasal transsphenoidal pituitary surgery in adenomas with parasellar extension

Background: Pituitary adenomas with parasellar extension present a technical challenge for adequate visualization and gross total resection (GTR). The endoscope improves identification of parasellar extension, however, additional intraoperative imaging adjuncts can further augment visualization. Intraoperative ultrasound (iUS) may provide a viable and cost-effective solution for intraoperative imaging. We sought to assess the ability of intraoperative ultrasound to predict extent of resection on 3-month postoperative magnetic resonance imaging (MRI) in pituitary adenomas with parasellar extension. Methods: Twenty consecutive patients undergoing endoscopic endonasal transsphenoidal surgery for pituitary adenomas with the assistance of intraoperative ultrasound were prospectively collected. Intraoperative ultrasound findings were recorded during each case. 3-month postoperative MRI studies were reviewed in a blinded fashion to assess for residual tumor and compared with the intraoperative ultrasound findings. Results: Median preoperative Knosp grade was 2. Cavernous sinus invasion was encountered intraoperatively in 3 patients, all of whom were Knosp grade 3 preoperatively. Median operative time was 152 min. Based on iUS findings, 17 patients were expected to have a GTR while 3 patients underwent subtotal resection. 18 patients completed a 3-month postoperative MRI. The iUS and MRI findings were concordant in 16 cases (88.9%) with only two instances of discordance. Conclusion: Intraoperative ultrasound can reliably predict tumor resection as assessed by 3-month postoperative MRI in pituitary adenomas with parasellar extension. Image capture and interpretation may vary based on operator experience. Ultrasound provides reliable immediate assessment of extent of resection, identification of normal pituitary gland and other important neurovascular structures.