Endoscopic supraorbital extradural approach to the cavernous sinus: A cadaver study. Laboratory investigation

Object. The cavernous sinus is a small complex structure located at the central base of the skull. Recent extensive use of endoscopy has provided less invasive approaches to the cavernous sinus via endonasal routes, although transcranial routes play an important role in the approach to the cavernous sinus. The aims of this study were to evaluate the feasibility of the purely endoscopic transcranial approach to the cavernous sinus through the supraorbital keyhole and to better understand the distorted anatomy of the cavernous sinus via endoscopy. Methods. Eight fresh cadavers were studied using 4-mm 0° and 30° endoscopes to develop a surgical approach and to identify surgical landmarks. Results. The endoscopic supraorbital extradural approach was divided into 4 stages: entry into the extradural anterior cranial fossa, exposure of the middle cranial fossa and the periorbita, exposure of the superior cavernous sinus, and exposure of the lateral cavernous sinus. This approach provided superb views of the cavernous sinus structures, especially through the clinoidal (Dolenc) triangle. The lateral wall of the cavernous sinus, including the infratrochlear (Parkinson) triangle and anteromedial (Mullan) triangle, was also clearly demonstrated. Conclusions. An endoscopic supraorbital extradural approach offers excellent exposure of the superior and lateral walls of the cavernous sinus with minimal invasiveness via the transcranial route. This approach could be an alternative to the conventional transcranial approach.