Sphenoid sinus symmetry and differences between sexes.

OBJECTIVES: To evaluate the anatomic variations of neurovascular structures adjacent to the sphenoid sinus and their agreement between right and left sides as well as differences between sexes. METHODS: Forty-five cadavers were dissected (24 men, and differences between sexes and agreement of anatomic variations of the sphenoid sinus between sides were analyzed. RESULTS: The mean distance from the sphenoid sinus ostium to the anterior nasal spine was greater in males than in females by an average of 3.0 mm (p = 0.001) while the mean difference of distances between the right and left side was -1.1 +/- 3.1 mm. Female cadavers had a greater frequency of optic-carotid recess (p = 0.04) and dehiscence over the maxillary nerve (p = 0.02), as well as greater relative risk of optic nerve protrusion (p < 0.001), and dehiscence over the internal carotid artery (ICA) (p = 0.002). In male cadavers the intersinus septum was inserted on the course of the ICA 3.5 times more often than in female (p = 0.02). Agreement of anatomic variations between sides ranged from moderate to almost perfect depending on the structures evaluated. CONCLUSIONS: There are anatomic differences of the sphenoid sinus between sexes and between right and left sides, and these differences should be taken into consideration during surgery.