2025 Proffered Presentations
S069: CONTRALATERAL MEDIAL TRANSORBITAL CORRIDOR TO THE INFRAPETROUS REGION AS A COMPLEMENT TO THE ENDOSCOPIC ENDONASAL APPROACH
Chandrima Biswas, MD1; Moataz D Abouammo, MD1; Jaskaran Gosal, MD2; Guilherme Mansur, MD1; Mohammad Bilal Alsavaf, MD1; Ludovica Pasquini, MD1; Maithrea S Narayanan, MBBS, MMED3; Daniel M Prevedello, MD, MBA1; Ricardo L Carrau, MD, MBA1; 1The Ohio State University Wexner Medical Center; 2All India Institute of Medical Sciences Jodhpur, India; 3Hospital Kuala Lumpur Jalan Pahang, Malaysia
Introduction: The infrapetrous region lies below the petrous bone and consists of the jugular tubercle, jugular foramen, hypoglossal canal, and occipital condyle and provides passage to the lower cranial nerves (IX, X, XI, XII). Accessing this region is a surgical challenge. Endoscopic endonasal ‘far medial approach’ (FM-EEA) has emerged as an alternative to the open approaches. However, it requires mobilization or transection of the eustachian tube and lateralization of the internal carotid artery (ICA). It also requires the removal of buccopharyngeal fascia and prevertebral muscles. The contralateral medial transorbital (cMTO) approach has been described as an adjunct to the endoscopic endonasal approach (EEA) to reach the petrous apex. In this cadaveric study, we have assessed the feasibility of using the cMTO route as a complement to the endoscopic endonasal transpterygoid transclival approach to reach the occipital condyle and morphometrically compared the surgical maneuverability and exposed area with the far medial endoscopic endonasal approach (FM-EEA).
Methods: Ten fresh preinjected cadavers (20 sides) were dissected with neuronavigation completing the endoscopic endonasal transpterygoid transclival approach on each side and the cMTO on the contralateral side to expose the infrapetrous region till the occipital condyle. This was followed by further dissection i.e. removal of the nasopharyngeal mucosa, buccopharyngeal fascia, and prevertebral muscles, and if necessary further maneuvers such as mobilization or resection of the ET tube, lateralization of the carotid through the endonasal corridor (FM-EEA) to reach the occipital condyle. The area of exposure in the infrapetrous region, volume of surgical freedom (VSF), craniocaudal, and mediolateral angle of attack (AoA) were measured for each approach (cMTO and FM-EEA).
Results: The mean area of exposure of the infrapetrous region through the cMTO and the FM-EEA was 265.11± 56 mm2 and 222.81 ± 76 mm2 (p=0.001) respectively. The mean AoA was 15.78 ± 0.8o and 11.33 ± 0.8o (p=0.03) in the cMTO and EEA respectively in the craniocaudal axis and the mediolateral AoA was 12.41 ± 0.67o and 19.06 ± 0.89o (p=0.07) respectively for cMTO and EEA. The VSF was 1724.5 mm3 and 1476.1 mm3 (p=0.004) respectively for cMTO and EEA.
Conclusions: The cMTO when combined with EEA can access the infrapetrous region till the occipital condyle. It provided significantly more area of exposure and VSF compared to the FM-EEA. It also provided a substantially more craniocaudal AoA. This suggests better surgical maneuverability, and a larger area of the infrapetrous region exposed through the cMTO compared to the FM-EEA. Adding cMTO to the EEA also avoided the resection of nasopharyngeal mucosa, buccopharyngeal fascia, and prevertebral muscles. It avoided the mobilization or transection of the eustachian tube and lateralization of the ICA which may be required when using the endonasal route alone.
