2025 Proffered Presentations
S384: FULLY ENDOSCOPIC COMBINED ENDONASAL AND TRANSORAL APPROACH TO SKULL BASE TUMORS AT THE CRANIOVERTEBRAL JUNCTION
Ana Sofia Alvarez, MD; Maria Jose Cavagnaro, MD; Joaquin Chuang, MD; Jonathan B Lamano, MD, PhD; Matei A Banu, MD; Juan C Fernandez-Miranda, MD; Stanford University
Introduction: The craniovertebral junction (CVJ), comprising the lower clivus, foramen magnum, atlas (C1), and axis (C2), presents significant anatomical challenges for surgical access due to its complexity and proximity to vital neurovascular structures. Tumors affecting this region often require complex surgical approaches to achieve complete resection. Traditionally, the transoral approach, typically performed using a microscope, has been considered the gold standard for ventral access to the CVJ, though it is associated with significant morbidity related to soft palate splitting and an increased risk of tracheostomy. Alternatively, the endoscopic endonasal approach (EEA) has gained popularity, offering less trauma to the soft palate but limited caudal access, particularly when attempting to fully access the anterior arch of C1 and the body of C2.
We present a detailed step-by-step guide to a combined fully endoscopic endonasal and transoral approach to access midline extradural skull base tumors extending from the clivus into the upper cervical spine.
Methods: We conducted anatomical dissections using two formalin-fixed, color latex-injected cadaveric specimens. The dissections were performed in a stepwise manner and documented with endoscopic images. A 4-mm, 0-degree rigid endoscope was utilized, along with standard endoscopic equipment and instruments. Throughout the dissection, we identified and described the key surgical steps for the combined endoscopic approach, providing detailed explanations of the relevant surgical anatomy. Additionally, a relevant clinical case was reviewed to exemplify each step of the procedure, correlating the surgical images with the anatomical dissections, and emphasizing the principles and practical applications of this technique.
Results: We provide a comprehensive explanation of the surgical steps and reconstructive technique, highlighting the advantages of combining both approaches. Additionally, we discuss key preoperative and postoperative considerations. This technique is specifically focused on extradural skull base tumors, as we find the transoral approach unsuitable for intradural lesions due to the risk of infection and potential for meningitis.
The main limitation of the EEA to the CVJ is the restricted caudal access beyond C1 due to nasal bony structures superiorly and palatal soft tissues inferiorly. In contrast, the transoral approach allows caudal access down to the C2-C3 intervertebral disc; however, reaching the odontoid process and anterior arch of C1 would require splitting the soft palate. Soft palate splitting has been associated with dysphonia, dysphagia, velopharyngeal insufficiency, and postoperative tracheostomy. To avoid soft palate manipulation, we opted to combine both approaches using a complementary technique to ensure complete exposure while minimizing complications. This technique overcomes the caudal limitations of the endonasal approach and the cranial limitations of the transoral route, providing extensive access to the lower clivus, anterior arch of C1, the odontoid process, and the body of C2.
Conclusion: The fully endoscopic combined endonasal and transoral approach offers a versatile and minimally invasive technique for managing complex skull base tumors at the CVJ. It provides a broader range of access than either approach alone, while reducing surgical morbidity. This is particularly important for midline skull base tumors, where adequate exposure is critical to achieving complete resection.