Applied anatomy and radiologic study on transnasal endoscopic optic nerve decompression

Objective To provide anatomic and radiologic basis for performing the transnasal endoscopic optic nerve decompression.Methods 20 sides of cadaveric skulls were studied in this study.The optic canal and its related structures were dissected and measured,as well analyzed by three-dimensional images of workstations.The results of workstations were compared with that of gross anatomy.Results The optic canal could be classified as: the canal(1 side,5%),the semicanal(2 sides,10%),the impression(11 sides,55%),and the non-impression(6 sides,30%).According to its relationships with the sinuses,the optic canal could be further typed as: ethmoid sinus(3 sides,15%),sphenoid sinus(7 sides,35%),ethmoid and sphenoid sinus(9 sides,45%),sella turcica(1 sides,5%).For 60%(12 sides) specimens,the posterior ethmoid sinus closed to optic canals.For 80%(16 sides) specimens,ophthalmic arteries located in the interior inferior of the optic nerve at the intracranial opening,however,for 85%(17 sides) of ophthalmic arteries located in the lateral inferior of the optic nerve at the intraobtial opening.Obvious apophysis of the internal carotid artery could be found in 70%(14 sides) specimens on the lateral wall of sphenoid sinus.A recess between optic canal and internal carotid artery was found in 95%(19 sides) specimens.The mean length of the interior wall of optic canal was about(10.23±1.31) mm.Anatomic survey concerning with the median distance between the joint of columella nasi and alae nasi,and landmark points,were similar to that of radiologic survey(P0.05).Conclusions The findings provide detail data of optic canal,which is valuable reference for performing the transnasal endoscopic optic nerve decompression.By CT and images workstations technology,we can precisely observe and measure optic canal.