J Neurol Surg B Skull Base 2024; 85(06): 575-586
DOI: 10.1055/s-0043-1775754
Original Article

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Approach to the Anterior Cranial Fossa

Edoardo Agosti
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, 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, 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, Rochester, Minnesota, United States
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Stephen Graepel
2   Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, United States
,
Garret Choby 
1   Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, 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, 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, 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.
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Abstract

Introduction The development of endoscopic techniques has made endoscopic endonasal approaches (EEAs) to the anterior cranial fossa (ACF) increasingly popular. Still, the steps and nuances involved in the approach may be difficult to understand for trainees. Thus, we aim to didactically describe the EEAs to the ACF in an anatomically based, step-by-step manner with supplementary clinical cases.

Methods Six cadaveric head specimens were dissected. Endoscopic endonasal Draf I, IIA, IIB, and III frontal sinusotomies, endoscopic endonasal superior ethmoidectomy, and endoscopic endonasal transcribriform and transplanum approaches were modularly performed. The specimens were photodocumented with endoscopic techniques.

Results Draf I frontal sinusotomy started with the complete removal of the anteromedial portion of the agger nasi cell, exposing the medial orbital wall, cranial base, and anterior cribriform plate. Draf II frontal sinusotomy proceeded with the removal of the floor of the frontal sinus between the lamina papyracea and the middle turbinate (IIa), and the nasal septum (IIb) until the first olfactory filaments were exposed. Draf III proceeded by creating a superior septal window just below the floor of the frontal sinus. The bone of the ACF bounded by the limbus sphenoidale posteriorly, frontal sinus anteriorly, and the medial orbital walls bilaterally was removed; the cribriform plate was removed; and the crista galli was dissected free from the dural leaflets of the falx cerebri and removed.

Conclusion We provide a step-by-step dissection describing basic surgical steps and anatomy of the EEAs to the ACF to facilitate the learning process for skull base surgery trainees.

Keywords

step-by-step dissection - anatomical details - skull base surgery - endonasal approaches - anterior cranial fossa - transcribriform - transtuberculum-transplanum - draf frontal sinusotomies

Ethical Approval

This retrospective chart review study involving human participants followed the ethical standards of the institutional and national research committee and the 1964 Helsinki Declaration and its later amendments. The Human Investigation Committee (IRB 17-005898) of the Mayo Clinic approved this study.




Publication History

Received: 09 May 2023

Accepted: 27 August 2023

Article published online:
27 September 2023

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