Anatomical determinants of sphenoid sinus volume: insights from a meta-analysis of observational studies.

BACKGROUND: The sphenoid sinus is one of the most anatomically variable structures of the skull base. Its volume may be influenced by pneumatization patterns, septation, and the relationship to adjacent neurovascular structures, notably the internal carotid artery (ICA) and optic nerve (ON). OBJECTIVE: The systematic review and meta-analysis assessed the influence of sphenoid sinus volume on pneumatization patterns, neurovascular protrusions, and accessory septa, as well as demographic variables such as sex and age. METHODS: This systematic review and meta-analysis were conducted per PRISMA guidelines. Eligible studies involving anatomical and radiological studies of sphenoid sinus volume were included. Subgroup analyses were performed based on pneumatization type (conchal, presellar, sellar, postsellar), neurovascular protrusions, accessory septa, sex, and age. RESULTS: Twenty-seven studies involving 1263 observations were included. The pooled mean total sphenoid sinus volume was 9.30 cm3 [95% CI, 8.56-10.03]. Sinus volume increased progressively with pneumatization, from conchal (2.41 cm3) to postsellar types (11.26 cm3). Accessory septa and protrusion of the ICA and ON were associated with significantly greater volumes. Sphenoid volumes were higher in males by 2.07 cm3 (1.02+1.05 cm3) and positively correlated with age in children (r = 0.69), confirming active developmental expansion but declined in the elderly (r = - 0.29), capturing a volumetric plateau and potential senescent structural remodelling. No laterality differences were observed. Egger's test indicated no significant publication bias (p = 0.7633). CONCLUSION: Sphenoid sinus volume was significantly predicted by pneumatization type, neurovascular protrusions, septal complexity, sex, and age. These findings provide critical anatomical reference values to enhance surgical planning and reduce risk in skull base interventions.