Combined Intraoperative MRI and Endoscopic Endonasal Approaches for Nonpituitary Skull Base Lesions

Introduction: Endonasal endoscopic approaches and intraoperative MRI (iMRI) are becoming established as valuable surgical techniques for pituitary tumors, but there has been little reported in combining these two techniques for nonpituitary skull-base tumors. We report our initial experience with this strategy using a movable high-field-strength iMRI.

Methods: Review of a prospective database of 470 iMRI procedures performed at Barnes-Jewish Hospital since April 2008 identified 11 patients who underwent 13 endoscopic endonasal resections for nonpituitary skull base neoplasms using 1.5T iMRI. Demographic, radiologic, surgical decision making, operative time, extent of resection, patient morbidity, and outcomes data were analyzed.

Results: Eleven patients (6 male; 5 female) safely underwent 13 endoscopic endonasal surgeries with iMRI. Mean age at surgery was 44 years (range, 12–70 years). Mean operative time was 10.4 hours (range, 4.9–13.6 hours). Pathology revealed chordoma (3), meningioma (3), epidermoid cyst, chondrosarcoma, craniopharyngioma, adenoid cystic carcinoma, and nasopharyngeal angiofibroma. iMRI demonstrated gross total resection (GTR) in 3 cases and subtotal resection (STR) in 10 cases. Additional resection was performed in 6 STR cases after iMRI (60%). Tumor tissue was pathologically confirmed in all post-iMRI resection specimens. Ten of 11 patients were alive at the time of analysis. One patient developed persistent pneumocephalus postoperatively, which resolved after a planned second stage operation during that admission. Otherwise, there were no CSF leaks and no meningitis. Patients noted stable or improved preoperative deficits after 12 (92%) of the surgeries. One new deficit was observed consisting of mild diminished sensation in the trigeminal distribution after resection of an angiofibroma invading the pterygopalatine fossa. At last follow-up, surveillance MRI showed stable residual disease in 55% of patients, while 45% had no evidence of disease. Mean follow-up was 12 months (range, 1–27 months).

Conclusions: Complex nonpituitary skull base lesions can be resected safely via the endoscopic endonasal approach with a movable high-field-strength iMRI. This method may maximize tumor resection from greater visualization while minimizing operative morbidity through a less invasive trajectory. Additional investigation is needed to determine the most appropriate application of this technique.