Ethmoid pneumatization and a large frontal-orbital-ethmoid mucocele

Abstract

Frontal-orbital-ethmoid mucocele is a slow-growing retention cyst of the fronto-ethmoid complex secondary to blockage of the sinus ostia. It may produce significant disfigurement of the periorbital region necessitating surgical intervention. Prior to surgery, it is imperative to study the mucocele's extent through the variable patterns of ethmoid pneumatization as evident from clinical, imaging (computed tomogram) and endoscopic evaluation. This is illustrated in a case study of a 41-year-old woman presenting with fullness below the right eyebrow, progressive proptosis, and gaze restriction. The provisional diagnosis of frontal-orbital-ethmoid muco(pyo)cele was confirmed at endoscopic surgery, when it was drained and marsupialized through ethmoidectomy and frontal sinusotomy. Understanding the relationship of an enlarging mucocele with the inconsistent pattern of ethmoid pneumatization is the primary determinant for an uneventful and complete surgery, and to minimize recurrence. The gradually expanding mucocele occupies the path of least resistance and encroaches into the available spaces of ethmoid labyrinth, distorting key anatomic landmarks and making surgical intervention potentially challenging. Thus, preoperative imaging corroborated with naso-endoscopy is of paramount importance to trace the lesion along ethmoid pneumatization, and determine the relative positions of structures vulnerable to surgery. This often requires a comparative study of the contralateral side because the mucocele generally obscures the pneumatization pattern and vital landmarks on its side. The present imaging tutorial studies the extent of a large frontal-orbital-ethmoid mucocele through interpretation of multiplanar computed tomography cuts, keeping in mind the unpredictable nature of its expansion as a function of the highly individualistic ethmoid pneumatization.

The axillary flap/trans‐agger approach as a supero‐lateral conduit to the effective frontal recess for marsupialisation of fronto‐ethmoid mucocele

“…To avoid an orbito‐vascular catastrophe, part of the mucocele abutting the AEA and extending posterior may remain unattended, increasing the recurrence potential (Figure 1H‐J). 4 Such situations mandate the axillary flap/trans‐agger conduit which provides a superior‐placed intra‐luminal endo‐vision with an effective vascular control. The technique is equally feasible in orbit and skull‐base erosion, and also in recurrences, since it can access the mucocele's free wall in its maximum dimensions.…”

“…In contrast, accessing the mucocele "looking up" through the transmeatal approach alone may put the AEA at risk. To avoid an orbito-vascular catastrophe, part of the mucocele abutting the AEA and extending posterior may remain unattended, increasing the recurrence potential (Figure1H-J) 4. Such situations mandate the axillary flap/trans-agger conduit which provides a superior-placed intra-luminal endo-vision with an effective vascular control.…”

Exploring the uncharted: Missing anatomical names in the Terminologia Anatomica

“…The lateral sinus ( sinus lateralis ; eponym: sinus of Grünwald, see Figure 1), also known as the suprabullar recess and the retrobullar recess , is a potential space limited superiorly by the roof of the ethmoid, anteriorly by the ethmoidal bulla, posteriorly by the basal lamella, medially by the lateral aspect of the middle nasal concha, and laterally by the orbital plate of the ethmoidal labyrinth (Bolger & Mawn, 2001; Dutta, 2019). The lateral sinus can be divided into two recesses: the retrobullar recess is a space limited by the ethmoidal bulla, the lateral aspect of the middle nasal concha, and the orbital plate of the ethmoidal labyrinth ( lamina papyracea ), whereas the suprabullar recess is located between the ethmoidal bulla and the fovea ethmoidalis.…”