2025 Poster Presentations
P362: ANATOMICAL STEP-BY-STEP DISSECTION OF COMPLEX SKULL BASE APPROACHES FOR TRAINEES: SURGICAL ANATOMY OF THE TRANSMASTOID HIGH CERVICAL APPROACH TO THE JUGULAR FORAMEN AND C1-C2 JUNCTION
Amedeo Piazza, MD, PhDs; Yohan A Alexander, BA; Fabio Torregrossa, MD; Luciano L Leonel, PhD; Michael Link, MD; Maria Peris Celda; Mayo Clinic
Introduction: The extradural portion of the Jugular Foramen and the occipito-C1-C2 junction regions are challenging surgical targets. The The transmastoid high cervical approach and its extensions are the most suitable methods for accessing these areas from the posterolateral perspective. While several cadaveric studies have refined these approaches, few offer a detailed, step-by-step description. Therefore, our aim is to provide a didactic description of the steps involved in the transmastoid high cervical approach to the jugular foramen and C1-C2 junction for trainnes.
Methods: Twelve sides of six latex injected, formalin-fixed cadaveric head specimens were dissected, using a surgical microscope, a 0° endoscope, and standard micro-neurosurgical instruments. The key steps of the transmastoid high cervical approach with vertebral artery transposition were photographed in 3D on illustrative specimens.
Results: First, a high cervical approach was performed to expose the extracranial craniocervical junction. The vertebral artery was identified in between the transverse processes of C1and C2 and, the posterior and lateral aspects of the transverse process of C1 were removed to free the vertebral artery. In the second step, a retrolabyrinthine mastoidectomy was performed, affording full exposure of the extradural portion of the jugular foramen, including the jugular bulb and vein, and cranial nerves IX, X, and XI. The occipital condyle was then drilled medially to expose the hypoglossal canal and nerve. The anterior arch of C1 was then followed contralaterally to reach and remove the contralateral lateral mass of C1 as well as the odontoid process of C2. The mesial portion of the contralateral V3 was visible at the end of the exposure.
Conclusion: The transmastoid high cervical approach is a powerful tool for the skull-base surgeon, offering a direct corridor to the extradural jugular foramen, the ventral and lateral portions of the craniocervical and C1-C2 junction, and the V3 segment of the vertebral artery. To facilitate easier understanding of the anterolateral approach and its extensions for trainees, we described the anatomy and surgical nuances in a didactic and step-by-step fashion.
