Endoscopic Sinus Approaches versus Transcranial Anterior Petrosectomy: A Volumetric Comparative Study of Access to the Petrous Bone and the Petrous Apex

Objective: The petrous portion of the temporal bone (PB) and the petrous apex (PA) are complex regions in the skull base that are affected by many pathologies. Surgical approaches to access these structures all have limitations for achieving maximal tumor resection with minimal comorbidity.

The purpose of this study is to evaluate petrous access by examining volume of removed bone via five different approaches: anterior petrosectomy “Hakuba–Kawase–Dolenc” (HKD) approach, endoscopic endonasal pure transclival approach (EEAT), endoscopic endonasal approach with internal carotid artery lateralization (EEA+ICA), contralateral transmaxillary approach (CTM), and CTM with internal carotid artery lateralization (CTM+ICA).

Methods: Ten cadaveric specimens were dissected using image guidance. Endoscopic endonasal techniques with or without contralateral Caldwell-Luc approaches in selected cases were performed to be compared with a classic open technique (HKD). Pre- and postdissection CT scans were obtained with 3D reconstructions of the volume resected on each specimen. Analyses of the resection and surgical aspects of the endoscopic techniques and HKD are discussed with the addition of two illustrative cases.

Results: For the PA alone, the greatest quantities of bone were resected via the HKD, CTM, and CTM + ICA. The HKD showed 71.2% of the PA (±1.87) resected; CTM alone 58.1% (± 6.8); and CTM + ICA 67.2% (±3.86). There was no significant difference between HKD and CTM + ICA (p = 0.741). The percent resected on the PA varied between the use of CTM (58.12% ± 6.83) and CTM + ICA (67.19% ± 3.86) although there were no statistically significant differences between them (p = 0.104). For the PB, the CTM + ICA provided the greatest quantity of bone resected (81.0% ± 1.1) followed by CTM (69.6% ± 10.9), with no significant difference between both techniques (p = 0.125). The volume resected with HKD was 46.8% ± 5.2; CTM and CTM + ICA showed significantly greater resection of the PB compared with the HKD (p = 0.001 and p < 0.0001, respectively).

Conclusion: The CTM approach offers a new corridor to reach the petroclival region. The CTM provides access to resect paramedian tumors with significant lateral and inferior extension into the petrous bone while minimizing complex maneuvers like carotid mobilization or manipulation of the eustachian tube diminishing the morbidity of the endoscopic. For PA lesions, the CTM + ICA provides similar access as the classic open techniques and superior access to the PB.