How I do it: endoscopic endonasal approach to the inferior third of the clivus.

BACKGROUND: Nowadays, endoscopic endonasal expanded approach targeting for the clival lower third is well described in literature. Nonetheless, great variations can be found among surgical groups, specially during the earlier stages of this procedure.

METHOD: We present a step by step description of the clival lower third approach until entering the dural space, setting its bony limits. We describe the basipharyngeal flap tailoring as a helpful option for latter reconstruction. The study of cadaveric specimens adds clarifying dissections.

CONCLUSIONS: The expansion in the coronal plane is providential in most of the intradural lesions of the inferior clivus. Basipharyngeal flap may help seal the surgical defects in this area.