The Importance of Cribriform-Lamella Angle in Endoscopic Sinus Surgery

The aim of this study is to evaluate cribriform-lamella (CL) angle and length of lateral lamella (LL) on CT scan and to correlate CL angle with LL length and Keros classification. Retrospective study analyzing 500 CT scans of PNS was performed at a tertiary care hospital. The CT scan anatomy of anterior cranial base was evaluated for Keros, CL angle and LL length. The relationship between these measurements was studied. Keros type I (75.2%) was the commonest finding in our study. Males have increased depth of olfactory fossa but there were no differences between the sides. Type A angle of CL (66.1%) was the commonest with females having an increased CL angle as compared to males. The LL length was 3.6 mm (± 0.8). There were no significant difference between sex/side of LL. Keros was found to be strongly correlated with the LL length whereas it has mild negative correlation with CL angle. There was no correlation between CL angle and LL length. Keros classification is the commonest criteria used to assess the risk of injury to anterior cranial base. However, we have found that the CL angle has an important role to play in the angulation/slope/level of anterior cranial base during endoscopic sinus surgery. CL angle needs to be considered as an important factor during endoscopic sinus surgery.