Maximizing the extent of tumor resection during transsphenoidal surgery for pituitary macroadenomas: can endoscopy replace intraoperative magnetic resonance imaging?

Abstract

Object. Endoscopic approaches to pituitary tumors have become an effective alternative to traditional microscopic transsphenoidal approaches. Despite a proven potential to decrease unexpected residual tumor, intraoperative MR (iMR) imaging is infrequently used even in the few operating environments in which such technology is available. Its use is prohibitive because of its cost, increased complexity, and longer operative times. The authors assessed the potential of intrasellar endoscopy to replace the need for iMR imaging without sacrificing the maximum extent of resection.Methods. In this retrospective study, 27 consecutive patients underwent fully endoscopic resection of pituitary macroadenomas. Intrasellar endoscopy was used to determine the presence of residual tumor within the sella turcica and tumor cavity. Intraoperative MR imaging was used to identify rates of unexpected residual tumor and the need for further tumor resection.Results. Intraoperative estimates of the extent of tumor resection were correct in 23 patients (85%). Of 4 patients with unacceptable tumor residuals, 3 underwent further tumor resection. After iMR imaging, the rate of successful completion of the planned extent of resection increased to 26 patients (96%). Rates of both endocrinopathy reversal and postoperative complications were consistent with previously published results for microscopic and endoscopic resection techniques.Conclusions. The findings in this study provided quantitative evidence that intrasellar endoscopy has significant promise for maximizing the extent of tumor resection and is a useful adjunct to surgical approaches to pituitary tumors, particularly when iMR imaging is unavailable. A larger prospective study on the extent of resection following endoscopic transsphenoidal surgery would strengthen these findings. (DOI: 10.3171/2009.6.JNS08916) Key woRds • intraoperative magnetic resonance imaging • intrasellar endoscopy • pituitary macroadenoma • residual tumorAbbreviations used in this paper: FOV = field of view; GTR = gross-total resection; iMR = intraoperative MR; STR = subtotal resection.

Intraoperative high-field MRI for transsphenoidal reoperations of nonfunctioning pituitary adenoma

“…Several reports of endoscopically assisted procedures as an adjunct to lowand high-field iMRI-guidance for resection control have been published. 48,66,73 In the present study, only a small subgroup (9%) underwent further tumor resection based on the endoscopic view; however, because of its possible benefit, the endoscope was always available during the procedures. A drawback of using the endoscope without iMRI for transsphenoidal reoperations may be that GTR was assumed in 40% of these patients based on the endoscopic assessment, and all of them showed tumor remnants on iMRI.…”

“…The varying anatomy and the presence of altered tissue and scarring in reoperations may have influenced their 100% rate of wrongly declared GTR based on the endoscopic view. 73 As 3D image-guided navigation systems are increasingly used in transsphenoidal surgery, others have already demonstrated how these techniques may reduce the morbidity of repeat transsphenoidal procedures, especially in cases of massive scarring and loss of normal anatomical structures after the initial surgery. 26,33,74 In our present experience, while it was often crucial for tailoring the approach to optimally expose the sella, the navigation could not reliably estimate the extent of resection.…”

“…These false-negative findings and the additional increase of the GTR rates made possible by iMRI is consistent with the literature. 48,66,73 Theodosopoulos et al 73 retrospectively analyzed the incidence of unexpected remnants detected by high-field iMRI after fully endoscopic transsphenoidal surgery. Their rate of 15% in 27 consecutive patients was small compared with published rates of residual tumor following microscopic resections, which led the authors to conclude that intrasellar endoscopy could replace iMRI with only a modest sacrifice in the extent of tumor resection.…”

Endoscopic endonasal transsphenoidal surgery for growth hormone–secreting pituitary adenomas

“…This finding contrasts with that in a study by Bohinski and colleagues, 4 who investigated the extent of macroadenoma resection via a microsurgical technique by using intraoperative MR imaging. In that series, residual tumor was 35 who performed intraoperative MR imaging after purely endoscopic transsphenoidal tumor resections. In a series of 27 patients, these authors were able to detect tumor remnants in the suprasellar cistern in 2 of 5 cases utilizing the endoscopic technique.…”

Surgical outcome of endoscopic endonasal surgery for non-functional pituitary adenoma by a team of neurosurgeons and otolaryngologists

“…The overall gross total tumor removal rate when surgery is conducted using eTSS for NFPA is 75.2-93% (5,7,9,14), which is higher than for mTSS. Theodosopoulos et al reported that endoscopy was equally effective compared to operative MRI when tumor resection rates are considered (22). However, the literature does not include detailed resection rates using eTSS to treat NFPA.…”