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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
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
3   Division of Neurosurgery, Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
,
A. Yohan Alexander
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Luciano C. P. C. Leonel
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Jamie J. Van Gompel 
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
4   Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Michael J. Link
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
4   Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Garret Choby
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
4   Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Carlos D. Pinheiro-Neto
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
4   Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Maria Peris-Celda
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
4   Department of Otolaryngology/Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, United States
› Author Affiliations
Funding This work was supported in part by Joseph I. and Barbara Ashkins Endowed Professorship in Neurosurgery and by Charles B. and Ann L. Johnson Endowed Professorship in Neurosurgery.
› Further Information
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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

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

Ethical Approval

This retrospective chart review study involving human participants was in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The Human Investigation Committee (IRB) of the Mayo Clinic approved this study.




Publication History

Received: 26 February 2023

Accepted: 19 June 2023

Accepted Manuscript online:
21 June 2023

Article published online:
02 August 2023

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