<prompt> The most common site of leak in CSF rhinorrhoea is:Sphenoid sinusFrontal sinusCribriform plateTegmen tympani  <response>: CSF rhinorrhoea is most commonly iatrogenic, following endoscopic sinus surgery. It can occur in surgery of frontal, sphenoid or ethmoid sinus. Injury to cribriform plate and ethmoid roof is the most common cause. 