A patient undergoing FESS for chronic sinusitis develops profuse clear fluid leak from the nose. The fluid is confirmed to be CSF by beta-2 transferrin testing. The most common site of inadvertent CSF leak during FESS is:

• A Cribriform plate (lateral lamella) ✓
• B Roof of the ethmoid (fovea ethmoidalis)
• C Sphenoid sinus lateral wall
• D Posterior wall of the frontal sinus

Explanation

The most common site of iatrogenic CSF leak during FESS is the lateral lamella of the cribriform plate, which is the thinnest area of the skull base (as thin as 0.05 mm). This occurs during over-aggressive medial dissection near the middle turbinate attachment. The Keros classification describes the variable depth of the olfactory fossa — a low Keros type III (deep olfactory fossa) dramatically increases the risk. The fovea ethmoidalis is thicker and less commonly violated.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.