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Abstract

Background: The sphenoid sinus exhibits considerable anatomical variability and lies adjacent to critical neurovascular structures, posing challenges during endoscopic sinus and transsphenoidal skull-base procedures. Region-specific morphometric data are essential to optimize surgical planning and minimize complications.
Methods: In this cross-sectional study, high-resolution CT scans of 200 adult patients (110 males, 90 females) from Northern India were analyzed. Anteroposterior length, transverse width, vertical height, and estimated volume of each sphenoid sinus were measured. Pneumatization patterns were classified as conchal, presellar, sellar, or postsellar. Septal anatomy (number, completeness, deviation, attachments) and bony protrusion/dehiscence of the internal carotid artery, optic nerve, and Vidian nerve were recorded. Bilateral and sex-based differences in dimensions and volume were assessed by independent-samples t-tests; volume differences across pneumatization types by one-way ANOVA with Tukey’s post-hoc tests; and categorical variables by Chi-square tests. Statistical significance was set at p < 0.05.
Results: Mean dimensions were 30.6 ± 4.2 mm (anteroposterior), 21.4 ± 3.5 mm (transverse), and 24.8 ± 3.7 mm (vertical), with no significant side-to-side differences (p ≥ 0.08). Mean sinus volume was significantly larger in males (9,200 ± 2,200 mm³) than in females (7,800 ± 1,800 mm³; t = 5.42, p < 0.001). Pneumatization distribution was sellar in 65%, presellar in 20%, postsellar in 10%, and conchal in 5%. Conchal (5,200 ± 1,000 mm³) and presellar (7,000 ± 1,500 mm³) volumes were significantly smaller than sellar (8,800 ± 2,000 mm³; p < 0.001 and p = 0.02, respectively), while sellar versus postsellar volumes did not differ (p = 0.45). Single septa occurred in 40%, two or more septa in 35%, and no septa in 25%; 12% of septa attached to the internal carotid artery and 8% to the optic nerve. Protrusion rates were 10% for the carotid artery, 7.5% for the optic nerve, and 4% for the Vidian nerve.
Conclusions: The sphenoid sinus demonstrates bilateral symmetry in linear dimensions but significant sex-related volumetric differences. Sellar pneumatization predominates, and septal and bony variations that tether or expose neurovascular structures are common enough to warrant meticulous preoperative CT evaluation. These findings should guide individualized surgical planning and inform the use of image-guided navigation to enhance intraoperative safety