Endoscopic-assisted paramedian supracerebellar infratentorial approach to the posterior portion of the third ventricle. Anatomical study and surgical cases.

EPSIA can be effective for approaching the PTV, enabling surgery along all boundaries, but especially on its roof and contralateral wall. In the not-enlarged ventricle, surgical maneuvers are feasible up to the level of the Monro foramen, becoming more limited anteriorly.