Introduction: The roof of ethmoid (fovea ethmoidalis) separates the ethmoidal cells from the anterior cranial
fossa. Medially the fovea attaches to the lateral lamella of the cribriform plate (LLCP), which is the thinnest bone of
the skull base. Hence, it is at a high risk of getting damaged during endoscopic sinus surgery. Objective: To evaluate
the height of lateral lamella of cribriform plate using the computed tomographic (CT) images of patients. Materials
and Methods: Coronal views of 80 computed tomography films of paranasal sinus region were studied. Coronal
sections at the level of centre of infra-orbital foramina were taken as the reference slide. The height of the lateral
lamella of the cribriform plate was measured and then classified according to Keros classification. Results: The CT
scans from 80 patients were analyzed. The median height of the LLCP in 160 sides was 3.3 mm (SD+1.63). The
LLCP height was 0 to 3.9 mm in 122 sides, 4.0 to 7.0 mm in 33 sides, and greater than 7.0m min 5 sides. The lateral
lamella of the cribriform plate averaged 3.47 mm (SD +1.68) in height on the right side and 3.08 mm (SD+1.59) on
the left. The LLCP height was greater on the right side in 55 patients, greater on the left side in 19 and equal on
both sides in 6 patients. The difference between sides was 0 to 1.9 mm in 78 patients, 2.0 to 3.9 mm in 1 patient, and
greater than 4.0 mm in 1 patient. Student t test was used to compare the mean height of LLCP on each side. t value
= 1.519. The difference of the height was not significant when right and left sides were compared (p = 0.131).
Conclusion: In our study, the median height of the LLCP was 3.3 mm. Mean height of the LLCP on right side (3.47)
was more than mean height of the LLCP on left side (3.08). But the difference was not statistically significant.
However, variations do exist between right and left sides. A surgeon must take proper caution while operating
in the area of lateral lamella of cribriform plate to prevent unintentional skull base injury and cerebrospinal fluid
leak. A proper pre-operative evaluation of computed tomography of para nasal sinuses is essential to avoid life
threatening complications during endoscopic sinus surgery.