Functional Endoscopic Sinus Surgery: Maxillary, Ethmoid, and Sphenoid (Cadaver)

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:

1. Functional Endoscopic Sinus Surgery: Maxillary, Ethmoid, Sphenoid (Cadaver)
2. Ethmoid Artery Anatomy (Cadaver)
3. Frontal Sinus Dissection (Cadaver)
4. DCR and Nasolacrimal System (Cadaver)
5. Parotid Dissection (Cadaver)
6. Thyroidectomy (Cadaver)