Sphenoid Sinus Pneumatization and Its Relation to Bulging of Surrounding Neurovascular Structures

Objectives: We investigated the bulging and dehiscence of neurovascular structures in the sphenoid sinus and their relationships to the pneumatization of the sphenoid sinus. Methods: One hundred sagittally hemisected cadaveric heads were examined. The degree of pneumatization of the sphenoid sinus was determined. Bulging and dehiscence of the internal carotid artery (ICA), optic nerve, maxillary nerve, and vidian nerve were examined, and the distances between these structures and the anterior or superior wall of the sphenoid sinus were measured. Additionally, the degree of bony thickness over these structures was determined. Results: The prevalences of bulging of the optic nerve, segments 1 and 3 of the ICA, and the maxillary and vidian nerves were 56%, 34%; 65%, 41%, and 52%, respectively. The greater the degree of pneumatization, the more frequently did the structures bulge into the sphenoid sinus. The optic nerve was found to be in close proximity to the anterior and superior walls of the sphenoid sinus. The bone over the surrounding structures was very thin, especially for the complete sellar type. Conclusions: The prevalence of bulging of the optic nerve, the ICA, and the maxillary and vidian nerves increased in proportion to the degree of sphenoid sinus pneumatization.