ForumWhich Routes for Petroclival Tumors? A Comparison Between the Anterior Expanded Endoscopic Endonasal Approach and Lateral or Posterior Routes
Introduction
The petroclival region is a “surgical” space limited anteriorly by the clivus, laterally by the petrous apex, medially by the brainstem, and posteriorly by the internal acoustic meatus (IAM). It extends from the dorsum sellae to the foramen jugularis. It's crossed by cranial nerves IVth to VIIIth and by the basilar artery with its branches (15). Because of their critical neurovascular relationships and their deep-seated location, the surgical removal of petroclival tumors remains a fascinating challenge. These tumors have long been considered as inoperable because the resection often was incomplete, with a high morbidity (48).
Advances in microsurgical techniques, operative microscopes, anesthesia, and neuroradiology have allowed the field of surgery to move forward with strategy for petroclival tumors. Through a few series from leading neurosurgeons, some surgical approaches turning around the petrous bone to the petroclival region have been reported with hopeful results but still frequent cranial nerves deficits 2, 6, 12, 25, 35, 42.
A century ago, the posterior retrosigmoid approach (RSA) was described to reach the petroclival region with the main disadvantage of working through the cranial nerves (11). Then, lateral approaches such as the anterior petrosectomy (AP) were proposed despite a “tricky” drilling around the intrapetrous otologic structures 23, 47. More recently, an anterior corridor has been developed with the expanded endoscopic endonasal approach (EEEA), which provides a broad exposure vertically from the cribriform plate to the craniovertebral junction and laterally toward the middle cranial or infratemporal fossas 4, 19, 21. From the literature 8, 9, 18, 41, the experience of our surgical team and anatomic dissections, we compared the anterior endoscopic endonasal approach with the classical posterior and lateral ones and propose decisional criteria for the management of petroclival tumors.
Section snippets
Anatomical Study
Five fresh cadaver's heads were harvested at the Anatomy laboratory of University Lyon 1 (Lyon, France), prepared with 10% formaldehyde, and then injected with colored latex (Phocéenne de chimie, Marseille/France; Aérographe Colorex Technics, Magenta et Cyan).
Five EEEAs were performed according to the technique described by Kassam et al. (21). A 180-mm long, 4-mm diameter endoscope was used with a 0 or 30° lense (Karl STORZ Endoskope GmbH, Tuttlingen, Germany). A bi-nostril path was necessary,
Anterior Approach
The anterior EEEA provides a simple straightforward access to the entire clivus, but the petrous apex is hidden behind the vertical paraclival segment of the ICA (Figure 1). The medial transsphenoidal transclival route runs through the middle clivus to the medial petrous apex and is bounded superiorly by the pituitary fossa, inferiorly by the sphenoid floor, posteriorly by the basilar artery with the brainstem and the cisternal segment of the VIth nerve, and laterally by the ICA. The lateral
Discussion
Under the same patronymic, different petroclival tumors can be encountered; some are extradural or intradural and others cystic or solid. Whatever their characteristics, these tumors still challenge the neurosurgeon, but with the recent development of the endoscopic endonasal surgery, one hopes to overcome some difficulties. To the best of our knowledge, no study summarizes all the routes that could be used to reach the petroclival region while at the same time examining which criteria lead to
Conclusions
From anatomical dissection, surgical experience, and the literature, it appears to us that each of these approaches has its own indications for petroclival tumors. There are different approaches for different petroclival tumors, not opposed, but complementary. The choice of the optimal approach will have to fit the assumed histological diagnosis, the tumor characteristics, the patient's status, and the surgical goal. Thus, extradural tumors extended to the clivus and cysts are better candidates
Acknowledgement
We thank the technical staff of the Department of Anatomy for their preparation of specimens and K. Erwin for correcting and editing our English.
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