Anatomical location of the vertebrobasilar junction: computed tomography morphometrics for planning endoscopic transsphenoidal transclival approaches.

BACKGROUND

The aim of this study was to determine the anatomical localisation and morphometry of vertebrobasilar junction (VBJ) by computed tomography (CT) images which may be helpful in planning the correct procedure before surgery such as endoscopic transsphenoidal transclival approach to the retroclival space.

MATERIALS AND METHODS

Vertebrobasilar junction level was determined on axial, coronal reformat and sagittal reformat images. Clivus length, the distances of the VBJ to the upper and lower end of the clivus and to the bottom of the sphenoid sinus were measured. In addition, the position and distance of the VBJ relative to the midline were measured. The vertebral artery dominance was determined and the position of VBJ relative to the midline was evaluated.

RESULTS

When compared by gender, 1, a, b and c values were significantly longer in males than in females (p < 0.05). The location of the bottom of the sphenoid sinus was higher than the VBJ level in 263 (98.1%) cases, equal to the VBJ level in 1 (0.4%) case, and lower than the VBJ level in 4 (1.5%) cases. There was no statistically significant difference between the distances to the midline when the VBJs with right and left localisation were compared (p > 0.05). A statistically significant relationship was found between vertebral artery predominance and localisation of VBJ relative to the midline (p < 0.001).

CONCLUSIONS

Careful perusal of CT images and the described VBJ morphometrics can help in accurate procedure planning to avoid basilar artery injury.