Journal of Neurological Surgery Part B: Skull Base, Table of Contents

J Neurol Surg B Skull Base 2024; 85(05): 526-539
DOI: 10.1055/a-2114-4660

Original Article

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Middle-Inferior Clivectomy, Odontoidectomy, and Far-Medial Approach

Edoardo Agosti

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

³Division of Neurosurgery, Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy

,

A. Yohan Alexander

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

,

Luciano C. P. C. Leonel

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

,

Jamie J. Van Gompel

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

⁴Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States

,

Michael J. Link

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

⁴Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States

,

Garret Choby

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

⁴Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States

,

Carlos D. Pinheiro-Neto

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

⁴Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States

,

Maria Peris-Celda

¹Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States

²Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States

⁴Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States

› Author Affiliations

MedOne

Abstract

Introduction The clival, paraclival, and craniocervical junction regions are challenging surgical targets. To approach these areas, endoscopic endonasal transclival approaches (EETCAs) and their extensions (far-medial approach and odontoidectomy) have gained popularity as they obviate manipulating and working between neurovascular structures. Although several cadaveric studies have further refined these contemporary approaches, few provide a detailed step-by-step description. Thus, we aim to didactically describe the steps of the EETCAs and their extensions for trainees.

Methods Six formalin-fixed cadaveric head specimens were dissected. All specimens were latex-injected using a six-vessel technique. Endoscopic endonasal middle and inferior clivectomies, far-medial approaches, and odontoidectomy were performed.

Results Using angled endoscopes and surgical instruments, an endoscopic endonasal midclivectomy and partial inferior clivectomy were performed without nasopharyngeal tissue disruption. To complete the inferior clivectomy, far-medial approach, and partially remove the anterior arch of C1 and odontoid process, anteroinferior transposition of the Eustachian–nasopharynx complex was required by transecting pterygosphenoidal fissure tissue, but incision in the nasopharynx was not necessary. Full exposure of the craniocervical junction necessitated bilateral sharp incision and additional inferior mobilization of the posterior nasopharynx. Unobstructed access to neurovascular anatomy of the ventral posterior fossa and craniocervical junction was provided.

Conclusion EETCAs are a powerful tool for the skull-base surgeon as they offer a direct corridor to the ventral posterior fossa and craniocervical junction unobstructed by eloquent neurovasculature. To facilitate easier understanding of the EETCAs and their extensions for trainees, we described the anatomy and surgical nuances in a didactic and step-by-step fashion.

Keywords

Keywords

skull base surgery - middle and inferior clivectomies - odontoidectomy - far-medial approach - foramen lacerum - pterygosphenoidal fissure

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