A Comparison of Postoperative MRI Changes between Endoscopic Endonasal and Open Approaches for Olfactory Groove Meningiomas: A Match Paired Analysis

Objective: Olfactory groove meningiomas may be associated with significant brain edema and surgical removal of these tumors may be associated with further injury to the frontal lobes. Endonasal access avoids frontal lobe manipulation, but little objective benefit has been demonstrated. Study Design: Retrospective case-cohort matched pair analysis. Methods: A retrospective review was performed at two institutions to identify patients who had either endonasal or open approach for resection of olfactory groove meningiomas. A matched pair analysis was performed and tumor volume, edema, FLAIR change, and porencephalic cave were volumetrically quantified. Results: Ten matched pairs (20 patients) were identified. The open approach was associated with more postoperative FLAIR change on MRI compared with the endoscopic approach although not statistically significant (13.3 cm³ [SD = 12.0] vs. 6.9 cm³ [SD = 10.0], p = 0.17). The endoscopic approach was also associated with smaller porencephalic cave volumes (1.7 cm³[SD=2.8] vs. 6.9 cm³[SD = 10.0), p = 0.058). In a multivariable model, the endoscopic approach was associated with less postoperative FLAIR change (p = 0.016) and smaller porencephalic cave volumes (p = 0.028). Conclusions: This study provides preliminary evidence that the endoscopic endonasal approach is associated with quantifiable improvements in postoperative brain imaging. Further studies including neurocognitive function are needed to confirm the significance of these findings.