Alromaih’s Entrance: A Proposed Entrance to The Posterior Fovea Ethmoidalis: A Cadaveric Study

Saud Alromaih, MD, MSc, FRCSc *¹, Ahmad Aldajani, MBBS, SBORL-HNS, JBORL, FKSU ^1,2,
Rana Alramyan, MBBS³, Ahmed Alsayed, MBBS ¹, Ahmad Alroqi, MD ¹, Mohammad O. Aloulah, MBBS¹, Abdulaziz S. Alrasheed, MBBS, MSc. FRCSc ¹, Ashwag Alqurashi, MD ⁴, Abdulrazag Ajlan, MBBS, FRCSc ⁵, Saad Alsaleh, MBBS, FRCSc ¹

1. Department of Otorhinolaryngology Head & Neck Surgery, Faculty of Medicine, King Saud University, Riyadh, Saudi Arabia.

2. Department of Otorhinolaryngology Head & Neck Surgery, Faculty of Medicine, University of Jeddah, Jeddah, Saudi Arabia

3. Department of Otorhinolaryngology Head & Neck Surgery, National Guard Health Affairs, Riyadh, Saudi Arabia.

4. Division of Neurosurgery, Department of Surgery, King Saud University Medical City, Riyadh, Saudi Arabia.

5. Division of Neurosurgery, Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia.

*Correspondence to: Saud Alromaih, MD, MSc, FRCSc. Rhinology and Skull Base Surgeon, King Saud University, Riyadh, Saudi Arabia.

Copyright

© 2024 Saud Alromaih, MD,. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: 09 February 2024

Published: 01 March 2024

Abstract

Objectives: Primary: to verify the safety of a new and easy entrance to posterior fovea ethmoidalis without the use of image guidance systems. Secondary: To assess the Keros classification, Lamina papyracea, presence of onodi cell, optic canal and carotid canal dehiscence, low-lying skull-base, low-lying anterior and posterior ethmoid arteries, presence of concha bullosa and lastly presence of lateralized superior turbinate.

Materials and methods: An interventional and descriptive pilot cadaveric study. Four human fresh frozen cadaveric heads were used to verify the safety of the proposed entrance in eight sides. All the elements of the secondary objective were documented.

The vertical part of the middle turbinate was separated from the basal lamella, starting from the inferomedial aspect going upward to their attachment to the skull-base. That was followed by clear identification of the superior attachment of the superior turbinate to the skull-base. The ability to safely identify the skull-base just lateral to the superior attachment of the superior turbinate was verified. Lastly, image guidance system was used to confirm the identification of the skull-base.

Results: Eight nasal cavities were dissected, and each side of the nasal cavity was examined independently. Skull-base was easily and safely identified in all 8 sides without the need of image guidance system. It was then successfully confirmed by image guidance system in all 8 sides. Based on Keros classification, half of nasal cavities were having class two, other half were of class one. None were having orbital wall defect. None were having medialized orbital wall. None were having Onodi cell nor optic/carotid canal dehiscence. None were having low-lying skull-bases. Anterior ethmoid artery was found within skull-base in six of the nasal cavities, other two were found hanging in mesentery. Concha bullosa was found in five out of eight nasal cavities. Lateralization of superior attachment of middle turbinate was only found in one nasal cavity. Lateralization of superior attachment of superior turbinate was not recorded on any of the examined cadavers.

Conclusion: Accurate identification of the skull-base is the key point of a safe Endoscopic Sinus Surgery. Using this entrance with such landmarks could help the surgeon in identifying the skull-base earlier during the surgery to reduce the possibility of having adverse outcomes. However, this must be performed with all other known safety measure. Moreover, this study has major limitations to allow for its recommendation at the present time. This study was a pilot study performed on few cadavers that does not reflect the real surgery where we face bleeding, inflammation, and presence of nasal polyps and loss of landmarks in revision cases.

Keywords: Endoscopic sinus surgery; Skull-base; Fovea ethmoidalis; Basal lamella; Nasa surgery.

Introduction

Many endonasal endoscopic surgical procedures can be tackled using the endoscope which provides the surgeon with a clear and unobscured field of vision. Moreover, it provides the surgeon with the ability to inspect recesses with angled distal lenses [1]. Although endoscopic training and physician experience have increased significantly over the past decades, surgical complications such as optic nerve trauma and cerebrospinal fluid leak still occur [1,3,4]. Surgeons reporting such complications mention the primary cause to be a lack of orientation within the dissection field [1]. Because endoscopic sinus surgery (ESS) is now being performed more routinely, surgical strategies designed to reduce the risk of complications are more crucial than ever. The primary aim of this paper is to provide the necessary orientation to guide and verify the safety of a new and easy entrance to posterior fovea ethmoidalis without the use of image guidance systems. Secondary, to assess the Keros classification, Lamina papyracea, presence of onodi cell, optic canal and carotid canal dehiscence, low-lying skull-base, low-lying anterior and posterior ethmoid arteries, presence of concha bullosa and lastly presence of lateralized superior turbinate.

Materials and Methods

Data Acquisition

The study population is represented by 4 human fresh frozen cadaveric heads. They were analyzed and used to verify the safety of the proposed entrance in 8 sides at the anatomical lab of College of Medicine at King Saud University, Riyadh, Saudi Arabia. A descriptive pilot cadaveric study was carried out to report a description and a new route to identify the skull-base. Radiological assessment prior to dissection was performed to each of the cadaveric heads by evaluating their paranasal sinuses’ CT scans.  The inclusion criteria were: (1) age over 18 years old, (2) cadavers with both nasal sides in a fresh condition, (3) no previous dissection done in the nasal cavity, and (4) no state of decomposition. In addition, the Keros classification, Lamina papyracea, presence of onodi cell, optic canal and carotid canal dehiscence, low-lying skull-base, low-lying anterior and posterior ethmoid arteries, presence of concha bullosa and presence of lateralized superior turbinate were documented.

Dissection Technique

Data collection was carried out through the dissection of 8 sides of nasal cavity. First, the vertical part of the middle turbinate was separated from the basal lamella, starting from the inferomedial aspect going upward to their attachment to the skull-base. That was done by a combination of common instruments such as freer dissector, kerrison punch thru-cutting forceps and microdebrider. That was followed by clear identification of the superior attachment of the superior turbinate to the skull-base. The ability to safely identify the skull-base just lateral to the superior attachment of the superior turbinate was verified. Lastly, image guidance system was used to confirm the identification of the skull-base.

Data Collection and Analysis

The data was tabulated and graphed in Microsoft Excel and Microsoft Word, in the process of writing the results, conclusions, and recommendations of this study.

Ethical and Bioethical Principles

This was an interventional and descriptive pilot cadaveric study that was approved by the IRB committee with IRB number E-22-6782. The norms provided by the institution and all ethical principles such as confidentiality, justice, beneficence, autonomy, and non-maleficence were respected.

Results

We performed an anatomical study on a series of four fresh-frozen human cadavers. A total of eight nasal cavities were used in the study. Concha bullosa was found in 5 (63%) nasal cavities. According to Kerous classification, the studied nasal cavities were evenly classified into either class 1 (50%) or class 2 (50%). We did not notice low lying skull-base or lateralization of superior attachment of superior turbinate (ST) in our study. Lateralization of superior attachment of middle turbinate was only found in one (13%) nasal cavity. Six (75%) of the nasal cavities had the anterior ethmoid artery within the skull-base, while the remaining two nasal cavities (25%) had the anterior ethmoid artery hanging in mesentery. No Onodi cell, orbital wall defect, medialized orbital wall nor optic/carotid canal dehiscence were found in the studied nasal cavities. (Table 1) Finally, the skull-base was easily and safely identified in all subjects without the need of image guidance system. It was then successfully confirmed by image guidance system (navigation) in all 8 sides with no complications.

Table 1. Results Summery

Image 1: Endoscopic view of the left nasal cavity aiming at the skull base.

Image 2: Confirming the identification of the skull base endoscopically.

Image 3: Confirming the identification of the skull base on image guidance in the sagittal, axial and coronal planes.

Discussion

There are two techniques of Functional Endoscopic Sinus Surgery (FESS). First, Messerklinger technique, which aims to drain and aerate the sinuses, and to restore mucociliary clearance of the sinuses by a minimally invasive anterior-to-posterior technique. Second, a more conventional and radical posterior-to-anterior ESS called Wigand’s technique [5]. However, in practice, a combination of these techniques is typically used. On the other hand, our suggested route has a major advantage of early identification of the skull-base and preventing subsequent complications of FESS.

Superior turbinate plays a major role as a constant anatomical landmark of ESS. [(2,3] It can be identified even in patients who had multiple previous surgical procedures and in whom other landmarks may be missing [6]. In other studies [6-12], the superior turbinate was mainly used to identify posterior ethmoidal sinuses and sphenoid sinuses. It was used for further orientation during endoscopic posterior ethmoidectomy and sphenoidotomy [6]. In our study, we studied the relation between the superior turbinate and the skull-base which was found just lateral to the superior attachment of the superior turbinate.

Surgeons should rely on easily recognizable, consistent anatomic landmarks to guide surgery because accurate identification of the skull-base is the core of a safe procedure. By using the route suggested in our paper, the skull-base was easily and safely identified in all subjects without the need of image guidance system and with no complications.

Conclusion

Accurate identification of the skull-base is the key point of a safe ESS. Using this entrance with such landmarks could help the surgeon in identifying the skull-base earlier during the surgery to reduce the possibility of having adverse outcomes. However, this must be performed with all other known safety measure. Moreover, this study has limitations to allow for its recommendation at the present time. This study was a pilot study performed on few cadavers that does not reflect the real surgery where we face bleeding, inflammation, and presence of nasal polyps and loss of landmarks in revision cases.

Reference

1. IS; M. Endoscopic sinus surgery [Internet]. Annals of the Academy of Medicine, Singapore. U.S. National Library of Medicine; 1991 [cited 2023Feb25]. Available from: https://pubmed.ncbi.nlm.nih.gov/1781657/

2. Sandu K, Monnier P, Pasche P. Anatomical landmarks for transnasal endoscopic skull base surgery. European Archives of Oto-Rhino-Laryngology. 2012 Jan;269(1):171–8.

3. Al-Mujaini A, Wali U, Al-Khabori M. Functional Endoscopic Sinus Surgery: Indications and Complications in the Ophthalmic Field. Oman Med J [Internet]. 2009 Apr 1 [cited 2023 Feb 25];24(2):70. Available from: /pmc/articles/PMC3273939/

4. Kaluskar SK. Complications in FESS. Endoscopic Sinus Surgery [Internet]. 1997 [cited 2023 Feb 25];79–90. Available from: https://link.springer.com/chapter/10.1007/978-1-4471-0919-8_11

5. Kaluskar SK. FESS Technique. Endoscopic Sinus Surgery [Internet]. 1997 [cited 2023 Feb 25];51–69. Available from: https://link.springer.com/chapter/10.1007/978-1-4471-0919-8_8

6. Bolger WE, Keyes AS, Lanza DC. Use of the Superior Meatus and Superior Turbinate in the Endoscopic Approach to the Sphenoid Sinus. Otolaryngology–Head and Neck Surgery [Internet]. 1999 Mar 1 [cited 2023 Feb 25];120(3):308-13. Available from: https://onlinelibrary.wiley.com/doi/full/10.1016/S0194-5998%2899%2970267-6

7. Eweiss AZ, Ibrahim AA, Khalil HS. The safe gate to the posterior paranasal sinuses: Reassessing the role of the superior turbinate. Vol. 269, European Archives of Oto-Rhino-Laryngology. 2012. p. 1451–6.

8. Kim S-S, Lee J-G, Kim K-S et al (2001) Computed tomographic and anatomical analysis of the basal lamellas in the ethmoid sinus. Laryngoscope 111:424–429

9. Kim H-U, Kim S-S, Kang S et al (2001) Surgical anatomy of the natural ostium of the sphenoid sinus. Laryngoscope 111:1599– 1602

10. Gheriani H, Flamer D, Orton T et al (2009) A comparison of two sphenoidotomy approaches using a novel computerised tomography grading system. Am J Rhinol Allergy 23:212–217

11. Orhan M, Govsa F, Saylam C (2010) A surgical view of the superior nasal turbinate: anatomical study. Eur Arch Otorhinolaryngol 267:909–916

12. Millar DA, Orlandi RR (2006) The sphenoid sinus natural ostium is consistently medial to the superior turbinate. Am J Rhinol 20:180–181.