Anatomical and imaging studies of optic canal decompression via a trans ethmoid-sphenoid approach under neuroendoscope

Wang Xingdong; Zhang Hengzhu; Yan Zhengcun; Wang Xiaodong; She Lei; Dong Lun; Li Yuping; Wei Min

doi:10.11850/j.issn.1009-122X.2018.02.011

Abstract：Objective To improve the safety and accuracy of optic canal decompression via a trans ethmoid-sphenoid approach under neuroendoscope.Methods Three dimensional CT scan and reconstruction of the optic canal were performed respectively on 6 dry cadaver heads (12 sides).The related anatomic parameters were measured and calculated on CT images.Then the heads were cut open along the horizontal plane and sagittal plane in order,and the related anatomic parameters were also measured.The relative data measured by two methods,CT image and entity dissection,were compared.Simulated surgery of trans ethmoid-sphenoid neuroendoscopic optic canal decompression was performed on 6 flesh adult cadaver heads (12 sides),and the anatomic landmarks of the approach were observed and recorded.Results The circumferences of the orbital opening,cranial opening and middle of the optic canal were (16.42 ± 1.56) mm,(17.32 ± 1.60) mm and (13.58 ± 1.42) mm.The maximum effective drilling widths of the medial wall of optic canal in orbital opening,cranial opening and middle of the optic canal were (7.82 ± 2.63) mm,(8.05 ± 2.77) mm and (6.92 ± 2.01) mm.The angle between the line linking the center point of the tubercular recess with the cranial opening of the optic canal and the horizontal coordinate was (17.23 ± 1.34)°.At the orbital opening of the optic canal,ophthalmic arteries were under the optic never in 2 sides (16.7％) and lateral-inferior portion in 10 (83.3％).Conclusions The endoscopic trans ethmoid-sphenoid optic canal decompression is a minimally invasive surgery with direct approach and complete decompression.Careful reading the CT images and making the related measurement preoperatively,using a variety of positioning methods can improve the accuracy of surgery.