Posterior ethmoid cells may pneumatize the sphenoid bone posteriorly, giving rise to the
Onodi cell. The lateral wall of this cell is closely related to the optic nerve & the internal carotid artery.
Right posterior ethmoidectomy, sphenoidotomy, and draining the content in the
Onodi cell (Figure 3) were performed and found whitish bloody mucoid discharge in the
Onodi cell with dehiscence of the superior wall exposing the right optic nerve.
Onodi cell mucoceles are rare entities that can cause devastating ocular complications if not treated promptly.
Optic neuropathy and acute visual loss caused by an isolated mucocele of an
Onodi cell have been reported.
This being an
Onodi cell, while operating on this patient the surgeon should be aware of this variation as there is an increased risk of injuring the optic nerve.
The scans were reviewed for the presence of deviated nasal septum, paradoxical middle turbinate, Haller cell,
Onodi cell, and pneumatisation of the middle turbinate and uncinate process.
The most posterior point of an
onodi cell of the posterior ethmoid may extend upto 1.5 cm beyond the most anterior point of the anterior wall of the sphenoid sinus.
This is important because approaching laterally and superiorly through the lateral portion of the ethmoid sinus could easily injure the optic nerve, or in the case of an
Onodi cell, cause entry into the intracranial cavity.
The Anatomical variations identified in CT are Agger nasi (17.3%), Pneumatisation of MT (34.6), Enlarged ethmoid bulla (13.4%), Paradoxical MT (11.5%), Everted Uncinate (1.9%), Haller cell (7.6%),
Onodi cell (11.5%) and Frontal sinus cells (11.5%).
Dissection of the left posterior ethmoid cells revealed the presence of a superior
Onodi cell (sphenoethmoid cell) above the sphenoid sinus (figure, B).
So, for visualising bulla ethmoidalis and other hidden ethmoidal air cells like Haller cell and
Onodi cell, CT PNS is the investigating modality of choice beyond doubt.
In what year, according to Christmas et al (Rhinoscopic Clinic), was the
Onodi cell first described?
