PROTRUSION OF THE OPTIC-NERVE INTO THE ETHMOID AND SPHENOID SINUS - PROSPECTIVE-STUDY OF 150 CT STUDIES

Damage to the optic nerve is a serious complication of intranasal sinu s surgery. Protrusion of the optic canal into the sphenoid sinus is a major risk factor. In this prospective study of 150 CT studies, we fou nd this anatomical variation in 8% of cases. It was consistently assoc iated with pneumatisation of the ipsilateral anterior clinoid process. Protrusion of the optic nerve into the posterior ethmoid cells was ne ver observed. CT is a useful part of the preoperative investigation of patients undergoing intranasal sinus surgery. Axial and coronal image s obtained or by direct acquisition by reconstructions are necessary t o show the position of the optic nerve.