Sphenoid septations and their relationship with internal carotid arteries: anatomical and radiological study.

OBJECTIVES/HYPOTHESIS: We sought to investigate the anatomical relation of the intrasphenoid septations to the internal carotid artery (ICA).

METHODS: Twenty-seven preoperative high-resolution computed tomography angiographic (CTA) scans with 1 mm of separation acquisition were examined. In addition, an endoscopic endonasal approach and high-resolution computed tomography were done on 27 fresh-frozen cadaveric heads. The number of intrasphenoid septa and their relation to the ICAs were analyzed endoscopically and radiologically. Complete and incomplete septations were included in the analysis. A total of 54 sphenoid sinuses were studied.

RESULTS: Out of 27 sphenoid sinuses radiologically studied from real patients, 23 (85%) and 11 (41%) had at least one or two septa, respectively, touching one of the ICA. Out of 27 sphenoid sinuses endoscopically examined from cadavers (excluding one conchal type), 24 (89%) had at least one septation inserted in the ICAs. Two or more septations were inserted in the carotid prominence in 48% of sphenoid sinuses. The radiological examination of the anatomical specimens revealed similar results, with discrepancy in just one case (1/27) where it did not identify an incomplete septation inserting at ICA. No significant differences were found between the groups. From a total of 54 sphenoid sinuses studied, 47 (87%) had at least one septum related to the ICA, and only 13% presented a typical isolated midline septation.

CONCLUSIONS: As demonstrated both radiographically and endoscopically, most intrasphenoidal septa insert at the parasellar or paraclival carotid prominence. As such, extreme care should be taken when identifying and removing these septations intraoperatively.