The radiological anatomy of the anterior skull base

Two complications dominate the thoughts of any surgeon undertaking functional endoscopic sinus surgery (FESS), namely damage to orbital structures and fractures of the fovea ethmoidalis. To avoid these complications, a detailed knowledge of the paranasal sinus anatomy of the patient is essential. This is usually assessed using preoperative computerized tomography (CT) scans of the paranasal sinuses. Analysis of 151 CT scans, measuring the height of cribriform plate below a supraorbital horizontal and above the hard palate was performed. Variation of shape and take-off angle of the fovea ethmoidalis was also measured. Comparison between left and right sides, and between scans showing radiological features of sinonasal disease and normal scans, was undertaken. Five patterns of fovea ethmoidalis were identified. No statistically significant difference between left and right sides was demonstrable for any parameter, irrespective of pathological status.