Background Patients who undergo surgery for purely intracranial pathologies, such as olfactory
groove meningiomas, via an endoscopic endonasal approach have significantly increased
postoperative nasal volumes. In these cases, usually the only remaining structures
are the anterior septum and inferior turbinates. Excessive removal of nasal structures
such as the middle turbinates and the ostiomeatal complex result in permanent changes
in airflow dynamics, and therefore, predispose the patient to postoperative crusting
and the need for debridement. In contrast, the superior ethmoidal approach maximizes
the preservation of critical nasal structures while still allowing enough space to
sufficiently access the anterior cranial base. This approach creates a more physiologic
airflow by preserving the middle turbinates, uncinate process, and bulla ethmoidalis,
subsequently decreasing nasal morbidity. In this article, we quantify the amount of
ethmoid bone preserved by utilizing the superior ethmoidal approach instead of the
traditional approach in cases of olfactory groove meningioma.
Methods Six patients with olfactory groove meningioma underwent endoscopic endonasal approaches
for tumor resection. In three patients, we performed the traditional anterior cranial
base approach, while in the other three patients, we performed the superior ethmoidal
approach. Preoperative MRI scans were used to measure the area of ethmoid bone at
two separate slice locations. Postoperative scans were used to determine the resected
area at both slice locations as part of the surgical approach. The difference between
preoperative and postoperative measurements was calculated to quantify the amount
of preserved ethmoid.
Results In the three patients receiving the superior ethmoidal approach, there was satisfactory
visualization of the meningioma at the anterior cranial base with bilateral preservation
of the middle meatus, uncinate process, and bulla ethmoidalis. The tumor was completely
resected in these three cases. Compared with the traditional approach, the superior
ethmoidal approach resulted in greater preservation of sinonasal structures, with
52.7% of ethmoid preservation (average residual area of 3.67 cm2) in the plane of the greatest orbital dimension, and 65.2% of ethmoid preservation
(5.45 cm2) in the plane of the anterior sphenoid wall.
Conclusion The endoscopic superior ethmoidal approach for purely intracranial pathologies minimizes
the unnecessary resection of crucial physiologic structures within the nasal cavity,
such as the middle turbinates and components of the ostiomeatal complex, while still
allowing sufficient access to the anterior cranial base. The ethmoid seems to be better
preserved posteriorly compared with anteriorly during this approach.