Sagittal and coronal dimensions of the ethmoid roof: A radioanatomic study

Background: Understanding the anatomy of the ethmoid roof is critical to safe surgical outcomes. Normative data regarding the height and slope of this region have been somewhat limited, derived primarily from cadaveric coronal computed tomography (CT) studies. With triplanar imaging programs, precise multidimensional measurements of the ethmoid roof are now possible. We present a radioanatomic study to characterize normative sagittal and coronal dimensions of the ethmoid roof. Methods: Bilateral measurements were taken in 100 consecutive sinus CT scans using ThinClient 3D software. In the sagittal plane, the height of the ethmoid roof was measured in quadrants at five equidistant points between the frontal beak and sphenoidface, referencing the nasal floor. In the coronal plane, the ethmoid roof was measured at three points at the level of the anterior ethmoid artery and at two points at the junction of the posterior ethmoid and sphenoid sinuses. Results: When examined sagittally, the right side showed significantly lower skull base heights in the anterior ethmoi compared with the left side (59.0 mm versus 59.8 mm, p 0.017; 53.7 mm versus 54.5 mm, p = 0.0004). Coronal mec surements of the anterior ethmoid roof showed similar signi, icant differences. The anterior ethmoid roof had greater asyrr metries of height compared with the posterior ethmoid roof which was fairly constant. Conclusion: This study provides numerical correlates to accepted concepts regarding the shape and slope of the ethmoi roof. Differences in height of the skull base between right an le sides, especially in the anterior ethmoid sinus, may be a important surgical consideration. The posterior ethmoid roo appears to be relatively constant and should serve as a reliabi surgical landmark.