Asymmetry of the anterior skull base at the level of frontal ostium, a radioanatomical study

Abstract

Radioanatomical studies have shown that the ethmoid roof is asymmetric in 10 to 40% of individuals. The right ethmoid roof has been found on average to be lower compared to the left. The aim of this study was to extend existing results by assessing asymmetry between the right and left anterior skull base at the level of the frontal ostium. Curved multiplanar reconstruction was used to analyse 247 consecutive paranasal sinus CT scans. The corresponding left and right parasagittal profiles of the skull base marked from the anterior ethmoidal artery to the level of the orbital roof were superimposed and compared. Asymmetry greater than 1 mm was found in 87% of patients, greater than 2 mm in 40.5% of patients, and greater than 3 mm in 8% of patients. The prevalence of the patients with lower skull base on the right side was greater than those with lower skull base on the left side at a ratio of more than 2:1. Skull base asymmetry in the region of the frontal ostium is observed in a large percentage of the population and may be a potential source of complications during endoscopic sinus surgery.