Preoperative CT of a patient scheduled for endoscopic sphenoidotomy shows a highly pneumatised posterior ethmoid cell that extends superolateral to the sphenoid sinus, with the optic nerve coursing along its lateral wall. Which anatomical variant is described?

• A Onodi cell ✓
• B Haller cell
• C Agger nasi cell
• D Concha bullosa

Explanation

An Onodi cell, also called a sphenoethmoidal cell, is a posterior ethmoid cell that pneumatizes superolateral to the sphenoid sinus and carries the optic nerve or internal carotid artery in its wall. It is the most dangerous variant during endoscopic sphenoid surgery because the surgeon may mistake it for the sphenoid and injure the optic nerve. B Haller cell lies inferomedial to the orbit along the infraorbital canal, an agger nasi cell sits anterior to the frontal recess, and a concha bullosa is a pneumatised turbinate.

Reference: Stambough: Cummings Otolaryngology Head and Neck Surgery, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.