Morphological Variability of the Sphenoid Sinus Septations

Abstract The sphenoid sinus (SS) is a highly variable, anatomically complex structure located at the skull base and intimately related to critical neurovascular elements, including the internal carotid artery and optic nerve. A precise understanding of its internal septation patterns is essential for safe surgical navigation during transsphenoidal and skull base approaches. The aim of this study is to describe and classify the morphological variability of SS septations (SSs) using high-resolution computed tomography (CT), emphasizing their number, orientation, and relationships to key anatomical landmarks. A retrospective review of 253 adult CT and CT angiography scans (129 males, 124 females; mean age 51.7 ± 15.0 years) was performed. Septations were assessed for number, completeness, orientation, and attachment sites. Sinus morphology was further categorized as simple or complex based on septation symmetry and configuration. The mean number of septations was 1.68 ± 0.95. A single septum was present in 53% of cases, two in 29.6%, and three or more in 15%. Most septations were vertical (88.1%) and eccentric (57.7%). Simple configurations predominated (69.6%), whereas complex morphologies accounted for 29.2%. No significant sex-related differences were identified (p = 0.937). Septal attachment to the carotid canal occurred in 49.8% of cases (unilateral 34.0%, bilateral 15.8%), whereas attachment to the optic canal was found in 9.5%. Deviation toward the sellar wall was significantly associated with complex morphology (p = 0.015). SSs display notable interindividual variability, typically presenting as one or two vertical, eccentric septa frequently attached to the carotid canal. Owing to their proximity to vital neurovascular structures, detailed preoperative CT evaluation is imperative for precise surgical orientation and the safe execution of transsphenoidal and skull base procedures.