Techniques and challenges of the expanded endoscopic endonasal access to the ventrolateral skull base during the "far-medial" and "extreme medial" approaches.

Abstract

Expanding the ventrolateral skull base corridor from the midline of lower clivus to the petroclival fissure is a challenging endonasal surgical task. Resection of lytic lesions like chondrosarcoma can cause cranial nerve morbidities and injury of ICA, necessitating accurate knowledge of correlative endoscopic anatomy with stereotactic landmarks. We describe an extended endoscopic endonasal approach (EEA) for a right petroclival chondrosarcoma with the demonstration of ipsilateral surgical landmarks with contralateral normal correlates, using a stepwise comparative image-guided cadaveric dissection study. EEA for lytic lesions like chondrosarcomas needs to address brain shift and displacement of ICA, posing a chance for cranial nerve morbidities and ICA injury. Meticulous utilization of intraoperative stereotactic landmarks can help avoid and mitigate surgical complications.