Functional Endoscopic Sinus Surgery: Maxillary, Ethmoid, and Sphenoid (Cadaver)
Main Text
Table of Contents
Functional endoscopic sinus surgery (FESS), pioneered in the 1980s, has become the standard approach for the surgical management of various sinonasal conditions, such as chronic rhinosinusitis and nasal polyposis.1 This minimally-invasive technique involves the use of an endoscope to visualize and access the paranasal sinuses, allowing for precise and targeted removal of diseased tissue. FESS demonstrated superior outcomes compared to conventional surgical approaches. The recurrence rate of nasal polyposis after FESS is markedly lower (6.67% of cases), compared to a recurrence rate of 30% after conventional surgery.2 Furthermore, the use of FESS resulted in a notable 15% decrease in the length of the frontal rhinosinusitis surgery when compared to traditional open surgery.3
Chronic rhinosinusitis, in particular, is a prevalent and debilitating sinonasal disorder, affecting between 5% and 12% of the general population.4 This chronic inflammatory condition can significantly impair quality of life, leading to symptoms such as nasal congestion, facial pain, headaches, and olfactory dysfunction.5 In cases when the conventional medical management, including the use of intranasal corticosteroids and antibiotics, fails to provide lasting relief for patients with disease symptoms, FESS emerges as a pivotal intervention, aimed at restoring normal sinus drainage and ventilation through the targeted removal of diseased or obstructive tissue.6
The potential complications associated with FESS are: direct injury to the brain, double vision, damage to the nasolacrimal duct/excessive tearing, hematoma in the orbit, formation of synechiae, damage to the carotid artery, damage to the optic nerve, injury to the orbit and leakage of cerebrospinal fluid.
In a comprehensive retrospective study of functional endoscopic sinus surgery, the overall complication rate was found to be 0.50%. The rates for blood transfusion, toxic shock syndrome, hemorrhage necessitating surgery, cerebrospinal fluid leakage, and orbital injury were 0.18%, 0.02%, 0.10%, 0.09%, and 0.09%, respectively.7
The cadaveric video on FESS presented here offers a detailed and comprehensive guide to maxillary, ethmoid, and sphenoid sinus dissection. The step-by-step approach, coupled with the emphasis on anatomical considerations, makes this video an essential resource for healthcare professionals involved in the management of sinonasal disorders.
The procedure commences with proper cadaveric head placement and instrument setup. The cadaveric head is positioned in a manner that would be used during the actual surgical procedure, with the head slightly turned towards the surgeon. The height of the table is adjusted so that the surgeon's arm can rest comfortably on the torso, minimizing fatigue.
Initial visualization with a 0-degree view angle endoscope allows for the identification of key sinonasal structures, including the inferior turbinate, septum, and middle turbinate. While the middle turbinate is obvious in most patients, it can be difficult to identify in severe nasal polyposis. In such cases, it can be more easily identified superiorly at its attachment site. For the initial step of the operation, the double-ended periosteal elevator is utilized to gently move the middle turbinate medially. This maneuver is executed with caution to prevent the occurrence of skull base fracture and consequent cerebrospinal fluid (CSF) leakage. As the medialization progresses, the uncinate process becomes evident, along with the ethmoid bulla and the basal lamella situated posteriorly behind the ethmoid bulla.
The next procedural step involves the removal of the uncinate process, known as uncinectomy. The right-angle probe is employed to access the posterior aspect of the uncinate, facilitating its anterior fracture. Following mobilization, the uncinate is divided inferiorly using a backbiting forceps, allowing for precise removal. Afterward, the microdebrider is utilized to eliminate residual remnants of the uncinate process. With the completion of the uncinectomy, the subsequent step involves locating the natural ostium of the maxillary sinus. The natural ostium is typically located at the junction between the inferior middle turbinate, positioned behind the uncinate process. Following successful entry, gentle dilation of the maxillary sinus is performed to enhance visibility within its cavity. Utilizing the microdebrider, the maxillary sinus is further widened, particularly in instances where thick bone obstructs access. In such cases, the straight true cutting forceps may be introduced to facilitate additional opening of the maxillary sinus, particularly inferiorly.
Upon completion of the maxillary antrostomy, the natural opening is checked using a probe. Sensory feedback, such as feeling the roof of the sinus and identifying the transition to the lamina papyracea, aids in confirming the ostium's location. The subsequent step includes the removal of the ethmoid bulla. Initially, a J-shaped curette is utilized to palpate for the presence of the retrobullar recess, which may vary in prominence among individuals. Efforts are made to access this recess, although occasionally direct entry into the ethmoid bulla may occur. In such cases, anterior fracture of the bulla is executed. The removal of the bulla is facilitated using cutting forceps, ensuring thorough excision. The process continues until the ethmoid bulla is completely eliminated from the surgical field.
Following the excision of the ethmoid bulla, the lamina papyracea becomes exposed laterally. Subsequently, the basal lamella is identified at the corresponding level. Entry into the basal lamella provides access to the posterior ethmoid cavity, where partitions are meticulously removed using microdebrider and forceps for comprehensive clearance. To initiate the sphenoidotomy, the inferior portion of the superior turbinate is resected, creating space for further access. Following the turbinate resection, attention is directed towards locating the sphenoid sinus ostium. Afterwards, it is dilated and widened laterally to visualize the sinus interior. A posterior-to-anterior ethmoidectomy follows, skeletonizing the skull base while removing partitions within the sphenoid sinus. Finally, an angled endoscope enables dissection of the frontal recess, completing the FESS.
It is crucial to be aware of the Onodi air cells. These cells are typically asymptomatic but are located perilously close to the optic nerve and internal carotid artery, with a minimal bone separation. Misidentifying the posterior wall of these cells as the sphenoid sinus during endoscopic entry can potentially damage these critical structures. Therefore, precise identification and careful navigation around these cells are essential during FESS to prevent complications.8
Overall, this comprehensive cadaveric video guide on FESS is an essential educational resource that can contribute to standardizing surgical practices, improving surgeon proficiency, and ultimately optimizing the quality of care for patients with sinonasal disorders.
Check out the rest of the series below:
Citations
- Bunzen DL, Campos A, Leão FS, Morais A, Sperandio F, Neto SC. Efficacy of functional endoscopic sinus surgery for symptoms in chronic rhinosinusitis with or without polyposis. Braz J Otorhinolaryngol. 2006;72(2). doi:10.1016/s1808-8694(15)30062-8.
- Humayun MP, Alam MM, Ahmed S, Salam S, Tarafder KH, Biswas AK. Comparative study of outcome of the endoscopic sinus surgery and conventional surgery for nasal polyposis. Mymensingh Med J. 2013;22(1).
- Alekseenko S, Karpischenko S. Comparative analysis of the outcome of external and endoscopic frontal sinus surgery in children. Acta Otolaryngol. 2020;140(8). doi:10.1080/00016489.2020.1752932.
- Fokkens WJ, Lund VJ, Mullol J, et al. EPOS 2012: European position paper on rhinosinusitis and nasal polyps 2012. A summary for otorhinolaryngologists. Rhinology. 2012;50(1). doi:10.4193/rhino50e2.
- Hoehle LP, Philips KM, Bergmark RW, Caradonna DS, Gray ST, Sedaghat AR. Symptoms of chronic rhinosinusitis differentially impact general health-related quality of life. Rhinology journal. 2016;54(4). doi:10.4193/rhin16.211.
- Rosenfeld RM, Piccirillo JF, Chandrasekhar SS, et al. Clinical practice guideline (update): adult sinusitis. Otolaryngol Head Neck Surg. 2015;152. doi:10.1177/0194599815572097.
- Suzuki S, Yasunaga H, Matsui H, Fushimi K, Kondo K, Yamasoba T. Complication rates after functional endoscopic sinus surgery: analysis of 50,734 Japanese patients. Laryngoscope. 2015;125(8):1785-1791. doi:10.1002/lary.25334.
- Gaillard F, Hacking C, Ranchod A, et al. Sphenoethmoidal air cell. Reference article, Radiopaedia.org. Accessed on 19 May 2024. doi:10.53347/rID-1776.
Cite this article
Brown CS, Jang DW. Functional endoscopic sinus surgery: maxillary, ethmoid, and sphenoid (cadaver). J Med Insight. 2024;2024(161.1). doi:10.24296/jomi/161.1.
Procedure Outline
Table of Contents
- Fracture Uncinate Anteriorly
- Divide Uncinate
- Remove Uncinate
- Identify Natural Ostium
- Widen Maxillary Sinus
- Ensure Natural Ostium
- Palpate the Retrobullar Recess
- Remove Ethmoid Bulla to Fully Expose the Lamina Papyracea Laterally
- Identify Superior Turbinate
- Remove Basal Lamella
- Resect Inferior Portion of Superior Turbinate
- Dilate Sphenoid Sinus Opening
- Identify Sphenoid Sinus
- Remove Partitions along Skull Base
Transcription
CHAPTER 1
So we'll be starting the functional endoscopic dissection of the cadaver, and we’ll be focusing on the left sinonasal cavity. You can see that I have the cadaver head positioned in the way I would during surgery with the head slightly turned towards me. And I like the height of the table to be such that my arm is resting on my torso, and I'm not having to operate them from this type of position here. So, arm on the torso to minimize fatigue. So now I'm going to - I'm using a zero-degree scope to visualize the sinonasal cavity, and I'll just point out some structures initially. We obviously have the inferior turbinate here to the right of the screen, the septum, which is rather straight on this cadaver - and then we see the middle turbinate here.
CHAPTER 2
So for the first step of the operation, what I always do is to use the Freer elevator to medialize the middle turbinate, and I want to do this gently so that I don’t fracture the skull base and cause a CSF leak. So I’m going to gently medialize that, and already, you start to see the structures in the middle meatus. See the uncinate process here. See the ethmoid bulla here, and then behind the ethmoid bulla is going to be the basal lamella all the way posteriorly.
CHAPTER 3
The first step of the operation is to remove the uncinate process, or the uncinectomy. Here, I like to use the right angle probe to get behind the uncinate and fracture this anteriorly. I really try to fracture as much of it as I can. Sometimes the bone can be quite thick. I try to fracture this forward - like that. So I’m superior here, and then also, I want to fracture this inferiorly as well.
Once the uncinate is mobilized, I like to divide it with a backbiter, inferiorly here. And here you can see that I'm creating a cut right in the uncinate, and I can take more of the uncinate with a backbiter too if - if I want.
Here, I’m using the microdebrider to remove the remnants of the uncinate process, being very, very careful not to get too close to the lamina. So I just let the tissue fall into the debrider. This is the more inferior portion of the uncinate, which is heading posteriorly - removing that as well. So I think we have a pretty good uncinectomy at this point.
CHAPTER 4
And the next thing that I like to do is to look for the natural ostium of the maxillary sinus. Now the natural ostium will be approximately - sort of at the junction between the inferior middle turbinate - so here in this area. And it'll be behind the uncinate process, so I'm going to sneak in behind the uncinate and see if I can fall into the maxillary sinus, which I am right now - right here. And once I fall in, what I will do is to gently dilate the maxillary sinus. And I already start to see inside the maxillary sinus.
So again, I will use the microdebrider to widen that maxillary sinus a little bit more. Sometimes when you have the - have some thick bone there, we need to remove it with cutting instruments. So here I’m going to introduce the straight true cutting forceps - to open this maxillary sinus up. And what I will do is to further open up that maxillary sinus, inferiorly. So I’m going to push some of this tissue down here. Okay. And then I will debride the rest.
Once the maxillary antrostomy is completed, I like to use the probe to make sure that it isn’t - that it is the natural ostium. And I like to feel the roof of the sinus, and I feel where it transitions to the lamina - and it feels as if the lamella will be right there - right here, at this level. Often, if you push on the eye, you can see some transmission there. Not so much on this cadaver. But, we assume that the lamina will be approximately at this level.
CHAPTER 5
The next step is to remove the ethmoid bulla, so what I like to do is to use the J-curette to feel for the retrobullar recess.
Sometimes, there is a prominent retrobullar recess - sometimes not, but I'll try to get into that retrobullar recess. Sometimes, I enter into the actual bulla, and I like to fracture that anteriorly.
Here, I can use some cutting forceps to take down the rest of this bulla. I'm continuing to remove the bulla.
CHAPTER 6
Once the ethmoid bulla is removed, the anatomy that we see is - we have the lamina papyracea right here along this area here, and the next landmark that we see is the basal lamella, which is going to be here at this level. Notice that we're likely in the posterior ethmoid cavity here at this point. By taking down the bulla, we actually enter the basal lamella at least in this area, but I like to enter the basal lamella typically inferomedially in this area here.
CHAPTER 7
I’m going to use the curette to enter the basal lamella down here and gently fracture the basal lamella.
And as soon as I enter that basal lamella, I like to look for the superior turbinate to confirm that I'm in the posterior ethmoid cavity. So we see superior turbinate right there at the edge of my curette.
Here, I'm using the microdebrider to remove some of the basal lamella.
CHAPTER 8
Here, I’m going to use the cutting forceps to take down some more of the partitions in the posterior ethmoid cavity. And I'm going to remove the remainder of the posterior ethmoid partitions, which we see right here. So we're all the way back to the posterior ethmoid cavity here - and looks like we have a few more partitions. This bone is quite thick.
CHAPTER 9
For the sphenoidotomy, I like to resect the inferior portion of the superior turbinate, which is what I'll do at this point. Resecting the inferior part of the superior turbinate there, and just a little bit more. And the sphenoid sinus ostium should be at this level right here, and I like to use the Freer to find that.
See it right there? I’m just going to dilate that sphenoid sinus opening. So here's the sphenoid sinus opening, which I'm now widening.
There is the sphenoid sinus - see a little bit of some ossification there along the wall, but there is the sphenoid sinus.
CHAPTER 10
Once we identify the sphenoid sinus, I like to proceed with the ethmoidectomy in a posterior-to-anterior direction to ensure that the skull base is fully skeletonized. So I'm in the sphenoid sinus. We feel - we see skull base here, and we can follow that skull base along - here, here. Looks like there's a partition right there, so we'll remove that partition. Let me - before we skeletonize the skull base... And once we get to the area of the frontal recess, it's a good idea to switch to an angled scope since the visualization is somewhat limited. Okay. So we've completed the ethmoidectomy at this point except for the frontal sinus dissection. So we have the sphenoid sinus back here, and we can see the skull base as you come anteriorly, right along here, here, here - and then the frontal recess - as I had mentioned, the frontal recess I like to dissect with the angled scope using curved instruments. So that completes the ethmoidectomy, maxillary antrostomy, and the sphenoidotomy.