Endoscope-assisted endonasal versus supraorbital keyhole resection of olfactory groove meningiomas: comparison and combination of 2 minimally invasive approaches.

Objective: Although the endonasal endoscopic approach has been applied to remove olfactory groove meningiomas, controversy exists regarding the efficacy and safety of this approach compared with more traditional transcranial approaches. The endonasal endoscopic approach was compared with the supraorbital (eyebrow) keyhole technique, as well as a combined "above-and-below" approach, to evaluate the relative merits of each approach in different situations.

Methods: Nineteen cases were reviewed and divided according to operative technique into 3 different groups: purely endonasal (6 cases); supraorbital eyebrow (microscopic with endoscopic assistance; 7 cases); and combined endonasal endoscopic with either the bicoronal or eyebrow microscopic approach (6 cases). Resection was judged on postoperative MRI using volumetric analysis. Tumors were assessed based on the Mohr radiological classification and the presence of the lion's mane sign.

Results: The mean age at surgery was 61.4 years. The mean tumor volume was 19.6 cm(3) in the endonasal group, 33.5 cm(3) in the supraorbital group, and 37.8 cm(3) in the combined group. Significant frontal lobe edema was identified in 10 cases (52.6%). The majority of tumors were either Mohr Grade II (moderate) (42.1%) or Grade III (large) (47.4%). Gross-total resection was achieved in 50% of the endonasal cases, 100% of the supraorbital eyebrow cases with endoscopic assistance, and 66.7% of the combined cases. The extent of resection was 87.8% for the endonasal cases, 100% for the supraorbital eyebrow cases, and 98.9% for the combined cases. Postoperative anosmia occurred in 100% of the endonasal and combined cases and only 57.1% of the supraorbital eyebrow cases. Excluding anosmia, permanent complications occurred in 83.3% of the cases in the endoscopic group, 0% of the cases in the supraorbital eyebrow group, and 16.7% of cases in the combined group (p = 0.017). There were 3 tumor recurrences: 2 in the endonasal group and 1 in the combined group.

Conclusions: The supraorbital eyebrow approach, with endoscopic assistance, leads to a higher extent of resection and lower rate of complications than the purely endonasal endoscopic approach. The endonasal endoscopic approach by itself may be suitable for a small percentage of cases. The combined above-and-below approaches are useful for large tumors with invasion of the ethmoid sinuses.