3D CTA Reconstruction of the Maxillary Artery in the Percutaneous Approach to Foramen Ovale, and the Anatomo-Radiologic Correlation Using the Inverted Pyramid Concept

Introduction: The concept of the “inverted pyramid” focuses on the extracranial trajectory of the corridor, which the authors had previously introduced. It is intended to help identify anatomical structures at risk. Three segments are described: The inferior segment from the cutaneous penetration to the parotid duct, the middle third from the parotid duct to the lateral pterygoid muscle LPM, and the superior third from the LPM to the Plexus Triangularis. A CTA study was performed to characterize the course and potential injury of the maxillary artery.

Methods: So far 12 sides from six cadaveric heads have been injected with red (arteries) and blue (veins) latex. The arteries and surrounding structures were dissected and studied using microsurgical techniques. Special attention was given to the course and branching pattern of the maxillary artery. Complete exposure of the maxillary artery main trunk and branches was obtained by removing the zygomatic arch and coronoid process of the mandible, as well as by widening the pterygomaxillary fissure by removing the lateral pterygoid plate and all of the maxillary sinus walls. Twenty CT angiograms (3D reconstructions) were studied and correlated with the anatomic dissection findings.

Results: Forty sides from 20 head CT angiograms (CTA) of actual patients were also analyzed. The course of the maxillary artery (MA) was found to be lateral to the LPM on 21 CTA sides (52.5%) and medial to the LPM on 19 sides (47.5%). The medial type is closely related to the foramen ovale, whereas the lateral type is more distant from it. After evaluating the side congruency, nine cases (45%) had the medial type and ten (50%) the lateral configuration as a mirror image along the contralateral side. Interestingly, one case (5%) had a lateral configuration on one side and a medial configuration on the other.

Conclusion: We found the CTA 3D reconstruction to be beneficial in identifying the course of the MA regarding the foramen ovale for whatever trigeminal lesioning technique, allowing us to predict these two variants with 100% accuracy. In the lateral variant, the MA is always away from the percutaneous foramen ovale trajectory. In contrast, in the medial variant, the artery is near the foramen ovale, and in up to 16% of the cases, the MA is directly in the probe’s trajectory.

Publication History

Article published online:
07 February 2025