Cone-Beam CT Morphometry of the Foramen Rotundum and Adjacent Skull-Base Landmarks: Associations With Sphenoid Sinus Pneumatization

Background: The foramen rotundum (FR) is a key landmark in endoscopic skull-base surgery, transmitting the maxillary nerve (V2) from the middle cranial fossa to the pterygopalatine fossa. Its anatomical relationships may be influenced by sphenoid sinus pneumatization, affecting surgical corridors. Methods: This retrospective CBCT study analyzed 50 adult patients (100 sides). Bilateral morphometric measurements of the FR and its relationships with adjacent landmarks, including the vidian canal (VC), foramen ovale, optic nerve, anterior clinoid process, and skull-base midline, were obtained. FR protrusion and dehiscence were recorded. Sphenoid sinus pneumatization was classified using sagittal types, the Vaezi coronal classification, and the DeLano optic nerve classification. Statistical analyses evaluated bilateral differences and associations with pneumatization patterns. Results: The mean FR height was 5.11±1.68 mm, and the mean FR-VC direct distance was 8.70±1.90 mm. Several measurements showed significant bilateral asymmetry ( P <0.05), although strong interside correlations were observed. FR protrusion occurred in 62% of patients and dehiscence in 24%. Postsellar pneumatization (64%) was significantly associated with FR protrusion ( P =0.0069). Conclusions: CBCT provides reliable morphometric data for assessing FR anatomy. Extensive sphenoid sinus pneumatization increases the likelihood of FR protrusion and may influence the geometry of the transpterygoid surgical corridor.