Abstract:

Objective  To study the correct position between  internal carotid artery (ICA) and bone markers  of sphenoid sinus inner wall, and between ICA and center of the aperture of sphenoid sinus  in  endoscopic transsphenoidal pituitary surgery,and to help the positioning and protection of ICA in operation.Methods The initial operating plane  (IOP)was reconstructed by computed tomography angiography (CTA) images,which was perpendicular to the sagittal plane and  passed through the sphenoid sinus opening and the pituitaryfossa midpoint plane.Three-dimensional coordinate system was selected ,the origin was the center of the sphenoid sinus opening,the x-axis and the mirror body (sphenoid external) were overlapping and parallel to the sagittal plane,the z-axis was perpendicular to the sagittal plane,the  y-axis was perpendicular to the x-and z-axes.The relationship between the position of ICA and its  mark points were observed.The indexes contained the coordinates of inner side wall of the  same side ICA(IAM),and the inner side wall of the contralateral side ICA(CAM),the minimum distance from the midline of CAM and the depth of CAM were detected.Results  In IOP,only 37.5% ICA location and ICA promontory(ICAP) position corresponded accurately. IAM coordinates were 1.50,－0.3,and 0.55　 cm;CAM coordinates were  1.49,－0.30,and 1.52 cm; the minimum distance from midline of CAM was 6.2 mm; the average depth of ICA was 1.1 mm.Conclusion Determination of the coordinates of  ICA in  IOP can help the positioning and protection of  ICA in operation.The operation  within 6.2 mm at the medial level can be considered to be quite safe in IOP when  the sagittal plane passing through  sphenoid sinus opening is used as a reference.

Key words: endoscopic transsphenoidal surgery
, internal carotid artery;internal , carotid artery prominence