Surgical Nuances of Endoscopic Endonasal Upper Clivectomy for Radical Resection of Central Skull Base Tumors: Two-Dimensional Operative Videos

Abstract

Abstract INTRODUCTION With routine endoscopic endonasal approach (EEA) for resection of skull base tumors, it is difficult to remove tumors that extend behind the posterior clinoid process (PCP) and dorsum sellae due to the limited exposure. Critical neurovascular structures (internal carotid artery, cavernous sinus, pituitary gland), PCP and dorsum sellae obstruct tumor visualization. Posterior clinoidectomy gives an excellent wider operative view and allows radical resection of tumors in the retrosellar area, prepontine and interpeduncular cisterns. We modified the endoscopic posterior clinoidectomy for safer endonasal extradural posterior clinoidectomy and applied it in 44 patients with parasellar and retrosellar tumors. This is the largest clinical series of endonasal extradural posterior clinoidectomy in which the clinical outcomes were evaluated. METHODS An extradural upper clivectomy (with complete posterior clinoidectomies) following lateral retraction of the paraclival internal carotid artery and extradural pituitary transposition were applied while preserving the blood supply and venous drainage of the pituitary gland. No violation to the cavernous sinuses. In cases with prominent posterior clinoid process, a midline sellar dura cut was added to facilitate its extradural exposure. Forty-four consecutive patients, in whom this technique was performed, between 2016 and 2018 at Osaka City University Hospital, were reviewed. The pathology included 19 craniopharyngiomas, 7 chordomas, 6 meningiomas, 6 pituitary adenomas, 4 chondrosarcomas, and 2 miscellaneous. Utilization and effectiveness of this approach were further demonstrated with neuroimaging. RESULTS On radiological examination, the surgical field was 2.2 times wider in cases with bilateral posterior clinoidectomies than in cases without posterior clinoidectomy. Upper clivectomies were successfully applied in all patients without permanent neurovascular injury, with better maneuverability and greater resection rate of the tumors. Four patients experienced transient postoperative abducens nerve paresis, and one patient experienced transient postoperative oculomotor nerve paresis; nevertheless, the deficits recovered within 3 mo. CONCLUSION The extended EEA with extradural upper clivectomy creates an extra-working space and allows adequate accessibility with safe surgical maneuverability to remove tumors that extend behind the posterior clinoid and dorsum sellae.