3D Endoscopic Transtubular Anterior Petrosectomy for Petroclival Meningiomas: Assessment of Resection in Varying Tumor Volumes Utilizing a Synthetic Tumor Model

Background: Surgical excision of petroclival meningiomas remains a challenge for neurosurgeons. The complex anatomy of the petroclival region and the location of the target lesion are the main determinates when selecting an optimal surgical approach. Extradural anterior petrosectomies are commonly used in the resection of petroclival meningiomas, though the application of temporal retraction carries the risk of the venous complications. Endoscopic anterior clinoidectomies have recently been proposed to access lesions of this region. We investigate a less invasive 3D endoscopic anterior transpetrosal approach through a subtemporal keyhole craniotomy using a minimally invasive tubular retractor system for the management of petroclival meningiomas.

Methods: Anterior subtemporal keyhole craniotomies were performed on 5 preserved cadaveric heads (10 sides) previously injected with colored latex and medium (3 sides, 1.0–2.4 cm), large (4 sides, 2.5–4.4 cm), or giant (3 sides, >4.5 cm) synthetic tumor models to simulate petroclival meningiomas. A ViewSite™ Brain Access System of tubular retractors (Vycor Medical, Inc., Boca Raton, FL, USA) was placed into the keyhole and secured to supply minimal temporal retraction. Visiosense VSii and VSiii 3D endoscopes (Visionsense, Ltd., Petach Tikva, Israel), equipped with a 4.0-mm, 0°, rigid probe were placed through the retractor and, after identification of anatomic surgical landmarks, an extradural anterior petrosectomy was performed using endoscopic instruments. Endoscopic resection of each synthetic tumor was performed and the degree of resection was assessed using the Simpson Grading Scale.

Results: Resection was possible for all tumor sizes through this approach with application of the tubular retractor system. Gross total resections (Simpson Grade I) were achieved in all 7 medium and large petroclival meningiomas and in 1 giant petroclival meningioma. Simpson Grade II and III resections were achieved on the two remaining giant petroclival meningiomas, respectively. Enhanced anatomic visualization of the surgical field was facilitated with the use of the 3D endoscope, and endoscopic instruments and an electric drill were passed through the tubular retractors with no difficulty. The tubular retractors applied rigid, constant, and equally distributed pressure on the temporal lobe.

Conclusion: The application of 3D endoscopic transtubular anterior transpetrosal approaches in the treatment of medium and large petroclival meningiomas is both feasible and effective. Despite the demonstrated efficacy on those tumor types, resection of specific giant petroclival meningiomas still necessitate the use of traditional skull base microsurgical techniques. Further clinical studies are necessary to determine potential clinical complications.