Abstract
Frontal‐orbital‐ethmoid mucocele (henceforth, "the mucocele") is often slow‐growing and insidious, needing watchful observation. But when symptomatic, complete endoscopic marsupialization is the intervention of choice.2,3 The mucocele's free wall, generally seen occupying the frontal recess (FR) in the ethmoid infundibulum/third pass roof, has a convenient transmeatal endoscopic access. However, much of the dependent surface remains hidden supero‐lateral within the bony lateral nasal wall behind the agger nasi, and further posterior into the migrated, intercommunicating ethmoid airspaces along the skull‐base. Failure to address the mucocele completely by marsupializing only its visible, infero‐medial aspect through the transmeatal route alone results in limited sinus drainage, and subsequent recurrence. Here, understanding the concept of "effective FR" (eFR) is essential. The eFR is formed by considering the FR and the migrated ethmoid air� �cells as functional patho‐anatomic compartments for an expanding, space‐occupying lesion like mucocele. The surgical technique described here is based on eFR compartmentalization and the mucocele's preferential path of progress. This ensures complete marsupialization, a wider Draf IIa ventilation/drainage basin, and a safe, co‐planar, superiorly‐placed endoscopic vision ("endo‐vision") across the mucocele and the vascular structures of skull‐base.
