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3D Endoscope-Assisted Microsurgical Anatomy of a Combined Subtemporal Presigmoid Transtentorial Approach
Introduction: Lesions of the mid-clival and petroclival region pose a challenge to skull base surgeons due to the region’s complex neurovascular anatomy. A combined subtemporal presigmoid transtentorial approach allows for good anatomic exposure and preservation of the transverse sinus. Recent advances in 3D neuroendoscopy have helped surgeons obtain enhanced anatomical visualization of deep intracranial targets. Intracranial structures seen through an endoscope take on a different perspective when compared with the standard anatomical view provided by the surgical microscope. We evaluate the surgical anatomy of a 3D endoscope-assisted CSTP approach and assess its surgical feasibility and its potential benefits.
Methods: A combined subtemporal presigmoid transtentorial approach was performed on 9 preserved cadaveric heads (18 sides) injected with colored latex. A temporal craniotomy was performed, flush with the floor of the middle fossa, and extended posteriorly to the transverse sinus. A retrolabyrinthine mastoidectomy was then performed, exposing the presigmoid dura and the sinodural angle. The presigmoid and subtemporal dura was opened and the tentorium was cut up to its medial free edge. To properly assess the 3D endoscopic microanatomical and neurovascular exposure, the surgical window was divided into three compartments, the anteromedial, middle, and posterolateral. Each compartment was explored by multiple surgeons using both the microscope and the 3D endoscope.
Results: Our study provided a detailed comparison of the endoscopic anatomy and microscopic anatomy of the combined subtemporal presigmoid transtentorial approach. The 3D endoscope provided enhanced visualization of the anteromedial compartment. Optimal and safe endoscopic probe insertion points were identified, and surgical maneuverability was assessed in each corridor.
Conclusions: The use of a 3D endoscope in a combined subtemporal presigmoid transtentorial approach allowed for better visualization of the more anterior and medial neuroanatomical structures, including the basilar artery; clivus; origin of the superior and anterior inferior cerebellar arteries; and cranial nerves IV, V, and VI. It also provided an enhanced surgical exploration of the entire petroclival region. However, at this time, the 3D probe is still too large and restricts surgical maneuverability.