Radioanatomical evaluation of the foramen rotundum morphology in the context of endoscopic skull base surgery

BACKGROUND: Foramen rotundum (FR) is a bone-encased tunnel-like structure located in basis cranii (BC). The morphological features and relationships of FR with surrounding anatomical structures can affect the feasibility of endoscopic interventions that use this structure. In this study, the morphological features and relationships of FR with surrounding anatomical structures were radiologically investigated. METHODS: Temporal section CT images of 114 adult individuals were used to measure the lengths of the maxillary "strut" (MSt) at the levels of the openings facing the fossa pterygopalatina (FP) and BC sides of FR, the widths of the FR openings, the lengths of the FR lower edge, the distances of FR to the internal carotid artery (ICA), and the distances of FR to the foramen ovale (FO) structure in the oblique plane. The sagittal and horizontal plane openings were determined to determine the location of FR between FPP and FC. RESULTS: The results of the study showed that FR has significant variations in its morphological features and relationships with surrounding anatomical structures between individuals. The four types of FR that were defined according to the topographic location between FP and BC were: superomedial, superolateral, inferomedial, and inferolateral. FR was most commonly found as the inferomedial type. The width of the opening facing FP of FR was wider in men than in women. The length, width, and relationships of FR with surrounding anatomical structures were related to standard craniometric distances and were not related to the type of sphenoid sinus pneumatization. CONCLUSION: The findings of this study suggest that the variations in the morphological features and relationships of FR with surrounding anatomical structures can significantly affect the feasibility of endoscopic surgical methods that use FR as a surgical corridor. In addition, the values obtained for the distances of the bone structures that limit FR and the hole to the neighboring anatomical structures can be a guide in the preoperative planning of such surgeries.