2025 Poster Presentations
P059: STEP BY STEP CADAVERIC DISSECTION OF ENDOSCOPIC TRANSORBITAL PRETEMPORAL APPROACH TO THE TEMPORAL UNCUS AND VENTRAL BRAIN STEM
Abdulaziz Almusa1; Jae-Sung Park2; Francesco Corrivetti3; Matteo de Notaris4,5; Doo-Sik Kong, PHD6; 1Prince Sultan Medical Military City, Samsung Medical Center; 2Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea; 3San Luca Hospital; 4Laboratory of Neuroanatomy, EBRIS Foundation, European Biomedical Research Institute of Salerno, Salerno, Italy; 5Neurosurgical Clinic A.O.U. "San Giovanni di Dio e Ruggi d'Aragona", Salerno, Italy; 6Samsung Medical Center, Sungkyunkwan University
Introduction: Despite of advances in endoscopic skull base approaches, an effective access to the supraoculomotor region and tentorial incisura, particularly around the cerebral peduncle of midbrain, remains challenging. This study examines the feasibility of a transorbital approach to this parapeduncular region.
Methods: A cadaveric study was conducted on four head specimens to evaluate the feasibility of an endoscopic transorbital approach to the parapeduncular region. The procedure began with superior eyelid incision. under endoscopic guidance the greater wing of sphenoid drilled out completely followed by the exposure of the temporal and frontal dura. Interdural exposure of the lateral wall of the cavernous sinus was performed, followed by the drilling of the anterior clinoid process to expose the clinoidal triangle. A dural incision was then made superior to the petroclinoidal ligament to visualize the entrance of the oculomotor nerve into the oculomotor triangle. After exposing the entry point of the oculomotor nerve into the cavernous sinus the dural incision was extended to the temporal side. Gentle retraction of the mesial temporal lobe could expose the temporal base dura and tentorial incisura superiorly. The tentorial edge was identified to expose the crural and ambient cisterns. This enabled the oculomotor nerve to be followed posteriorly towards the cerebral peduncle, with the access path being parallel to the oculomotor nerve.
Results: The described technique allowed for successful exposure and navigation of the oculomotor nerve from its entrance at the oculomotor triangle to the cerebral peduncle. This approach provided a clear view of the parapeduncular region, demonstrating its potential feasibility. In two patients with invasive pituitary adenoma, we confirmed this surgical approach was proved to be effective to remove the lesion involving roof of the cavernous sinus and extending to the anterior boundary of midbrain.
Conclusion: The transorbital approach offers a feasible route to access the parapeduncular region, providing a parallel view of the oculomotor nerve not achievable with endoscopic endonasal methods. Further studies are required to validate the safety and effectiveness of this approach in the clinical setting.