Height and Shape of the Skull Base as Risk Factors for Skull Base Penetration during Endoscopic Sinus Surgery

Objectives: Computed tomography (CT) and magnetic resonance imaging have identified several risk factors for life-threatening complications of skull base penetration during endoscopic sinus surgery (ESS). We compared these risk factors between groups of patients with and without penetration. Methods: We performed a retrospective review of direct coronal paranasal sinus CT scans. Using preoperative CT scans of 100 patients without and 7 patients with penetration, we classified height into 4 groups and contour into 2 groups. The frequencies of shape and height differences of the right and left halves of the skull base were calculated in each group. Results: In 6 of the 7 patients who had skull base penetration, ESS was performed by a resident or junior staff member who had less than 3 years of experience with this technique. Shape asymmetry was seen in 4 of the 7 patients (57%) with penetration, which was a significantly higher rate than in patients without penetration (18 of 100; p = 032). The frequencies of a low skull base and a height difference were 15% and 28%, respectively. Conclusions: The most important risk factor for skull base penetration was the surgeon's inexperience. An asymmetry of shape of the right and left halves of the skull base was significantly related to inadvertent skull base penetration during ESS.