A Systematic Classification of Surgical Approaches for the Sphenoid Sinus: Establishing a Standardized Nomenclature for Endoscopic Sphenoid Sinus Surgery

Marn Joon Park; Jakob L. Fischer; Vijay R. Ramakrishnan; Kevin C. Welch; Dong-Young Kim; Tae-Bin Won; Jae Hoon Cho; Sue Jean Mun; Jivianne T. Lee; Daniel M. Beswick; Marilene B. Wang; Jeffrey D. Suh

doi:10.21053/ceo.2025.00069

Clinical and Experimental Otorhinolaryngology > Volume 18(2); 2025 > Article

Park, Fischer, Ramakrishnan, Welch, Kim, Won, Cho, Mun, Lee, Beswick, Wang, and Suh: A Systematic Classification of Surgical Approaches for the Sphenoid Sinus: Establishing a Standardized Nomenclature for Endoscopic Sphenoid Sinus Surgery

Review

Clinical and Experimental Otorhinolaryngology 2025; 18(2): 109-122.

Published online: April 8, 2025

DOI: https://doi.org/10.21053/ceo.2025.00069

A Systematic Classification of Surgical Approaches for the Sphenoid Sinus: Establishing a Standardized Nomenclature for Endoscopic Sphenoid Sinus Surgery

Marn Joon Park^1,^*

, Jakob L. Fischer^2,^*

, Vijay R. Ramakrishnan³

, Kevin C. Welch⁴

, Dong-Young Kim⁵

, Tae-Bin Won⁵

, Jae Hoon Cho⁶

, Sue Jean Mun⁷

, Jivianne T. Lee²

, Daniel M. Beswick²

, Marilene B. Wang²

, Jeffrey D. Suh²

¹Department of Otorhinolaryngology-Head and Neck Surgery, Inha University Hospital, Inha University School of Medicine, Incheon, Korea

²Department of Otolaryngology-Head and Neck Surgery, University of California, Los Angeles, Los Angeles, CA, USA

³Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN, USA

⁴Department of Otolaryngology-Head and Neck Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA

⁵Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea

⁶Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Hospital, Konkuk University School of Medicine, Seoul, Korea

⁷Department of Otorhinolaryngology-Head and Neck Surgery, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea

Corresponding author: Jeffrey D. Suh Department of Otolaryngology-Head and Neck Surgery, University of California, 200 Medical Plaza, Suite 550, Los Angeles, CA 90095, USA
Tel: +1-310-206-6688 Email: JeffSuh@mednet.ucla.edu

^* The authors contributes to this study as co-first authors.

Received March 10, 2025 Revised March 31, 2025 Accepted April 7, 2025

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The sphenoid sinus presents significant challenges during endoscopic sinus surgery. It is essential that surgeons employ strategies that effectively address sphenoid pathology while minimizing surgical risks and optimizing outcomes. Although nomenclature for maxillary and frontal sinus surgery is well established, there is currently no standardized nomenclature for sphenoid sinus surgery. We present a comprehensive review of techniques for accessing the sphenoid sinus and propose a common surgical classification system to better define and categorize these approaches. Each technique is classified based on surgical extent, anticipated operation time, complexity, potential complications, and expected wound healing, aligning with established standards in the literature. The proposed sphenoidotomy types are as follows: type I, sphenoid ostial dilation; type IIa, transnasal sphenoidotomy (sphenoidotomy without ethmoidectomy); type IIb, transethmoidal sphenoidotomy (sphenoidotomy with ethmoidectomy); type III, bilateral, common cavity sphenoidotomy, or “sphenoid drill-out;” type IV, transpterygoid approach, to expose the lateral sphenoid sinus recess; and type V, sphenoid nasalization, completely removing the sphenoid sinus floor. By standardizing the nomenclature for these techniques, we aim to enhance consistency in terminology for teaching, surgical planning, clinical research, and interdisciplinary communication in sphenoid sinus surgery.

Keywords: Sphenoid Sinus; Sphenoidotomy; Endoscopic Sinus Surgery; Functional Endoscopic Sinus Surgery; Chronic Rhinosinusitis

INTRODUCTION

The sphenoid sinus lies adjacent to critical structures such as the cavernous sinus, skull base, optic nerve, and internal carotid artery, posing unique challenges in endoscopic sinus surgery (ESS) [1,2]. Injury to any of these structures can result in serious consequences for both the patient and the surgeon. Therefore, surgeons must carefully select the extent of dissection to create a sphenoid opening that matches the patient’s pathology while avoiding the risks associated with overly extensive openings and drilling, which may prolong healing and increase the likelihood of scarring and stenosis [3-5]. Although these nuances are well recognized in frontal and maxillary sinus surgery, similar concerns for sphenoid sinus surgery have received limited attention in the literature.

The appropriate surgical technique to manage sphenoid sinus disease varies with the underlying pathology. Chronic rhinosinusitis (CRS) involving the sphenoid sinus is typically addressed concurrently with other sinuses during functional endoscopic sinus surgery (FESS) [6-8]. However, presentations may range from mild, isolated inflammation to erosive tumors with cranial nerve deficits or cases requiring access to a pneumatized lateral recess [4,9-15]. Additionally, conditions such as tumors, encephaloceles, mucoceles, and skull base lesions demand extra preoperative planning and careful technique selection [16-20].

Despite these complexities, the absence of a unified surgical nomenclature for the sphenoid sinus hampers communication among physicians and limits progress in clinical research. Recently, the extent of sphenoid surgery for CRS management, endoscopic skull base procedures, and transsphenoidal surgeries has become more standardized, suggesting that defining categories based on surgical extent is feasible. Unlike the well-accepted stepwise approaches used for maxillary and frontal sinuses, a similar nomenclature has yet to be established for sphenoid sinus surgery [21-23]. This review proposes a systematic, categorized nomenclature for various endoscopic approaches to the sphenoid sinus.

ETHICS STATEMENT

The Institutional Review Boards of the Inha University Hospital and the University of California, Los Angeles approved this research (No. 2023-11-003/No. 17-000024) and waived the requirement for informed consent given that no personally identifiable information was used. A comprehensive literature review was conducted to examine the various surgical techniques for accessing the sphenoid sinus. This review, combined with established practices, informed the development of a proposed common nomenclature that categorizes sphenoid sinus approaches in a progression from least to most surgically complex.

NOMENCLATURE OF THE ENDOSCOPIC SPHENOID SINUS SURGERY

We identified and classified various endoscopic techniques for treating sphenoid sinus pathologies by considering disease pathology, the extent of invasiveness, technical challenges, and risks of complications associated with each intervention. Focusing on the necessary anatomical landmarks to be “removed” or “taken out” to “open” the sphenoid sinus, each surgical approach was subsequently categorized based on surgical extent, surgical complexity and technical challenges, potential complications, estimated blood loss, postoperative care requirements, and the likelihood of long-term patency. Detailed considerations for each type are provided, including procedural descriptions and the rationale behind technique selection. An overview illustration of the sphenoidotomy types is presented in Fig. 1, with comprehensive information available in Table 1 and Figs. 2-7.

Type I sphenoidotomy: sinus ostial dilation

Type I sphenoidotomy involves the transnasal identification and dilation of the natural sphenoid ostium using a balloon catheter or another non-cutting, rigid instrument. The goal is to restore natural mucociliary function and enhance sinus drainage by venting the ostium. This technique can serve as either a primary or adjunct procedure under local or general anesthesia and may be combined with irrigation to evacuate mucoid or purulent secretions, providing immediate relief while minimally disrupting the sinonasal mucosa.

Type I sphenoidotomy may be an attractive option for patients who are unable or unwilling to undergo general anesthesia with symptomatic sphenoid sinus disease, as it can be safely performed under local anesthesia, avoiding the potential risks associated with general anesthesia (Fig. 2). This technique can be considered for patients with mild to moderate, isolated unilateral or bilateral sphenoid sinus disease not secondary to a tumor or mycetoma, and it may be used to investigate and treat incidentally discovered, asymptomatic disease. Additionally, this technique is beneficial for pediatric patients in whom removal of packing after more extensive intervention is challenging [24]. Finally, sphenoid ostial dilation is a viable option for managing postoperative sphenoid sinus stenosis.

The procedure entails identifying the natural ostium of the sphenoid sinus, which is located medial to the superior turbinate and can be approached with or without surgical navigation [25]. Under endoscopic guidance (Fig. 2B), the surrounding mucosa is dilated using a balloon catheter, careful bouginage with a curved suction tip, or by rotating a Freer elevator. The dilated mucosa permits the evacuation of pus and facilitates natural drainage (Fig. 2C) [26].

Disadvantages of this technique include poor visualization within the interior of the sphenoid sinus, the inability to safely obtain an adequate tissue biopsy, and a risk of postoperative ostial stenosis. Inadequate visualization may lead to missed pathology or incomplete evacuation, while debridement can be difficult due to the proximity of the middle turbinate and patient discomfort within the narrow sphenoethmoidal recess.

Type IIa sphenoidotomy: transnasal sphenoidotomy (sphenoidotomy without ethmoidectomy)

Type IIa sphenoidotomy involves transnasal identification and widening of the natural sphenoid ostium without complete anterior and posterior ethmoid dissection. The sphenoid ostium, located in the sphenoethmoidal recess by its typical position medial to the superior turbinate, can be visualized for enlargement [27,28]. For enhanced access, the middle and superior turbinates may be partially truncated or gently lateralized. Truncating the inferior aspect of the superior turbinate can improve visualization of the sphenoid ostium and allow more extensive lateral dissection into the posterior ethmoid when needed. If resection is warranted, the lower one-third of the superior turbinate can be safely removed with through-cutting instruments to preserve the olfactory mucosa [26]. The sphenoid ostium, situated in the upper third of the anterior sphenoid sinus wall, is then enlarged inferiorly to form a wider opening [3]. Care must be exercised when dissecting inferiorly along the sphenoid face to avoid injuring the posterior septal branch of the sphenopalatine artery, which is a common source of significant postoperative bleeding [3,5]. Prophylactic cautery along the inferior margin is strongly recommended, although excessive electrocauterization may cause scarring and stenosis, so meticulous technique is essential [3,5]. In cases of significant osteitis, drilling the anterior sphenoid wall to circumferentially enlarge the neo-ostium might be necessary; however, this increases the risk of stenosis and prolongs recovery. Generally, hand instruments are sufficient for identifying and enlarging the ostium.

Type IIa sphenoidotomy is recommended in cases where dissection of adjacent paranasal sinuses is unnecessary or when a previous type I sphenoidotomy has been unsuccessful or is technically challenging—such as in cases of sphenoid face ossification or disease processes like fungal mycetoma (Fig. 3A) or inspissated secretions (Fig. 3B), where limited dissection does not allow complete evacuation [29,30].

Compared with type I sphenoidotomy, the type IIa sphenoidotomy enables complete visualization of the sphenoid sinus, which allows for a more complete evacuation of purulent discharge or fungal debris [12,31-34]. Both the type I and IIa sphenoidotomy procedures can be performed under local anesthetic in patients who are poor candidates for general anesthesia, but there is a higher risk of bleeding in the type IIa sphenoidotomy, particularly if dissection is extended inferiorly along the sphenoid face. In comparison to more advanced surgical techniques, the type IIa sphenoidotomy provides a faster and potentially safer alternative to sphenoidotomy with ethmoidectomy (transethmoidal sphenoidotomy; type IIb) while minimizing risks to critical structures such as the lamina papyracea, optic nerve, and internal carotid artery, especially in cases involving an Onodi cell [35,36].

The risk of sphenoid stenosis may be higher with this technique, although modifications, such as the use of a mini-nasoseptal flap, can help minimize this risk. This flap involves elevating the posterior septal mucosa and rotating it posteriorly to cover the inferomedial exposed bony edges, thereby reducing stenosis (Fig. 3C) [15,37,38].

Type IIb sphenoidotomy: transethmoidal sphenoidotomy (sphenoidotomy with ethmoidectomy)

The type IIb sphenoidotomy is the standard transethmoidal approach performed during most routine endoscopic sinus surgeries. A complete ethmoidectomy is carried out to expose the basal lamella of the superior turbinate just anterior to the sphenoid sinus face [39,40]. The lower one-third of the superior turbinate may then be truncated, exposing the sphenoid face, which is palpated beginning medial to the superior turbinate and at the level of the maxillary sinus roof (Fig. 4B) [41]. Once the sphenoid sinus is entered, its face is dissected to create a large sphenoid antrostomy that incorporates the natural ostium, extending superiorly to the skull base and laterally toward the orbital margin if desired. Preoperatively, the presence of an Onodi cell—a superolaterally pneumatized posterior ethmoid air cell—must be noted, as it may position the sphenoid sinus more inferomedially than anticipated. Surgeons should also recognize that within an Onodi cell, the optic nerve and internal carotid artery might be dehiscent, necessitating extra caution [42].

As the workhorse of standard FESS, type IIb sphenoidotomy is essential for comprehensive sinus surgery [1,41,43]. This technique is particularly recommended for patients undergoing multi-sinus intervention, especially when ethmoid dissection is involved. A large sphenoidotomy enhances drainage of both the sphenoid and ethmoid sinuses and facilitates postoperative delivery of intranasal corticosteroids and irrigations, which is particularly beneficial in conditions such as allergic fungal rhinosinusitis or eosinophilic CRS with extensive mucin production (Fig. 4C) [44,45]. The type IIb approach offers distinct advantages over the type IIa procedure in inflammatory or neoplastic diseases—where polyps, fungal debris, or tumors extensively involve the sphenoid sinus—by improving drainage, topical medication delivery, and providing better exposure for instrumentation and visualization when disease extends into the ethmoids [46].

Type III sphenoidotomy: sphenoid drill-out

Type III sphenoidotomy, also known as the “sphenoid Draf III” or “sphenoid drill-out,” extends the type II approach by incorporating a posterior septectomy and removal of the intersinus septum to create a single, unified sphenoid cavity. This procedure may follow bilateral type IIb sphenoidotomy, a combination of unilateral type IIa and contralateral type IIb, or bilateral type IIa sphenoidotomy.

Initial dissection involves completing the appropriate bilateral type IIa or IIb sphenoidotomies. Truncating the lower portion of the superior turbinates allows the septum to be visualized bilaterally for the posterior septectomy, although lateralizing the turbinates is an alternative based on the surgeon’s preference. Caution must be exercised to avoid high resection of the superior turbinates and septal mucosa to reduce the risk of postoperative hyposmia [47,48]. The inferior limit of dissection is generally set just above the sphenoid floor. The posterior septal mucosa may be dissected and elevated as a mini nasoseptal flap—based on the posterior septal branch of the sphenopalatine artery—to line the sphenoid floor, or it may be ablated. The posterior septum is then removed to expose the intersinus septum and sphenoid rostrum. The mucosa covering the sphenoid rostrum should be gently mobilized inferiorly to protect the posterior septal branch. Subsequently, the rostrum, crista sphenoidalis, vomer ala, and sphenoidal concha are removed using cold steel instruments and/or a drill down to the level of the sphenoid floor. The intersinus septum is resected posteriorly until it approximates the sphenoid sinus’s posterior boundary, thereby creating a common cavity with minimal partitions that facilitate surveillance and improve drainage [13,49]. Because the intersinus septum often deviates toward the internal carotid artery, care must be taken to avoid excessive torque on this structure. If a mini-nasoseptal flap is raised, it can be used to cover the drilled surfaces along the sphenoid rostrum and floor.

The type III sphenoidotomy is particularly valuable in revision surgeries following previous type IIa/IIb procedures, in cases of significant osteitis or sphenoid narrowing—such as in longstanding allergic fungal rhinosinusitis or severe mycetoma (Fig. 5A)—and in tumors (e.g., inverted papilloma) that require additional access to achieve clear margins. It is also the standard approach for endoscopic skull base surgeries including neoplasms [13,19,49,50]. This approach provides a large, common sphenoid cavity that facilitates postoperative observation and disease monitoring. Additionally, the possibility of a binostril, two-surgeon technique may enhance access to the lateral recess of the sphenoid sinus and allow for more precise dissection around critical structures [51,52].

The dissection extent in type III sphenoidotomy can be tailored according to the surgical indication. These variations are particularly useful in skull base surgery to address pathology beyond the sinuses, such as pituitary neoplasms, Rathke’s cleft cysts, planum sphenoidale meningiomas, clival chordomas, and other lesions. The sphenoid sinus provides an optimal corridor for accessing skull base structures, including the sella, tuberculum, planum sphenoidale, and clivus, while minimizing recovery time and complications compared to transcranial approaches [53-55].

Modifications to the technique will vary based on the pathology addressed. For example, planum sphenoidale meningiomas may require removal of the adjacent posterior ethmoid sinuses and more extensive resection of the superior turbinates and nasal septum, whereas a clival chordoma may necessitate more aggressive drilling of the clival recess.

Type IV sphenoidotomy: transpterygoid approach

Type IV sphenoidotomy, traditionally known as the transpterygoid approach (TPA), is designed to access the lateral recess of the sphenoid sinus. This technique provides broad exposure to the lateral sphenoid sinus recess, creating a corridor for removing lesions such as mucoceles or tumors (Fig. 6A) and for repairing cerebrospinal fluid leaks or encephaloceles within the lateral sphenoid sinus recess (Fig. 6B). It is also useful when approaching tumors in adjacent regions, including the petrous apex, lateral clivus, cavernous sinus, and Meckel’s cave [56].

The procedure begins with an ipsilateral wide maxillary antrostomy, a total ethmoidectomy, and at least a type IIb sphenoidotomy. Complete dissection of the ethmoids improves visualization and facilitates access throughout the surgery [57]. Next, the sphenopalatine foramen is identified, and the posterior wall of the maxillary sinus is removed in a medial-to-lateral direction. This maneuver opens the pterygopalatine fossa (PPF) and approaches the infratemporal fossa (Fig. 6C). The contents of the PPF are then either resected or displaced inferolaterally to expose the pterygoid plates. Following this, the sphenoid ostium is enlarged laterally—a step that often requires cauterization or ligation of the sphenopalatine artery. When feasible based on the underlying pathology, careful efforts are made to avoid injuring the maxillary nerve (V2) and its branches, which can be traced by following the infraorbital nerve from within the maxillary sinus toward the foramen rotundum. In most cases the Vidian nerve is sacrificed to achieve wider access to the lateral sphenoid sinus recess, though preservation is possible in select situations [58]. Notably, type IV sphenoidotomy has been linked to decreased lacrimation and moderate to severe dry eye, particularly in patients with preexisting lacrimal deficiency [59]. Additional complications reported in the literature include hypoesthesia in the sensory regions of V2 and numbness in the gingival/palatal areas due to involvement of the greater palatine nerve, a branch of V2 [60].

Most inflammatory diseases, including CRS with nasal polyps and allergic fungal rhinosinusitis, are typically managed with type II–III sphenoidotomies. However, when complete exposure and full instrumentational access to the lateral sphenoid sinus recess are required, as in cerebrospinal fluid leak repair or tumor surgery, type IV sphenoidotomy provides the necessary far lateral access. Angled instrumentation and endoscopes further enhance exposure and visualization of the lateral sphenoid sinus recess. This technique offers an expanded surgical corridor for endonasal procedures (Fig. 6B, green area) and significantly improves the ability to address bony defects or invasive lesions within the lateral sphenoid sinus recess [59].

Type V sphenoidotomy: sphenoid nasalization

Type V sphenoidotomy, previously described as “sphenoid marsupialization” or “sphenoid nasalization,” is generally reserved for diseases that are refractory to prior sphenoid type IIb or III procedures or when a maximal sinus opening is preferable, such as cases of sinonasal tumors involving the sphenoid floor [60]. This technique may also be beneficial in situations where severe mucociliary dysfunction necessitates dependent drainage.

Type V sphenoidotomy can be performed unilaterally or bilaterally, although it is most commonly described as a bilateral procedure [4,30]. It may be executed with or without the creation of a mucosal flap to cover the exposed bone of the posterior pharyngeal wall over the clivus. One approach involves creating an inferiorly based flap using the mucosa of the sphenoid sinus floor. In this method, mucosal incisions are made superiorly at the level of the sphenoid os, medially along the septal mucosa, and laterally along the face of the sphenoid as far as possible. Vertical incisions are then carried from the septum and the lateral sphenoid face inferiorly to the posterior termination of the sphenoid sinus or to the anterior roof of the nasopharynx. These incisions cross the posterior septal branch of the sphenopalatine artery, which is cauterized either at or before the time of incision. Following this, the sphenoid face is removed to complete a type IIb sphenoidotomy, and the entire sphenoid floor is drilled inferiorly and posteriorly until it is flush with the posterior wall of the sinus (Fig. 7). The mucosal flap is then repositioned over the exposed bone of the posterior sphenoid wall and clivus [4].

Potential drawbacks of the type V sphenoidotomy include the considerable time required for complete removal of the sphenoid floor and the challenges of drilling through portions of the marrow-rich clivus, which may result in bleeding that is difficult to control—especially since packing in this area can be challenging. Additionally, this technique often leaves extensive areas of exposed bone that may require more comprehensive remucosalization along the posterior nasopharynx compared to other methods.

DISCUSSION

Given the wide spectrum of sinus pathologies encountered in the sphenoid sinus, a nuanced understanding of disease-specific surgical approaches is essential. Surgeons must choose the technique that best addresses an individual patient’s pathology while weighing the benefits, drawbacks, and specific equipment or reconstructive requirements associated with each approach. This necessity underscores the importance of systematically categorizing surgical techniques for the sphenoid sinus.

Classification schemes have been previously established for the maxillary and frontal sinuses [22,23]. For instance, most maxillary sinus pathologies are managed via a middle meatal antrostomy; however, in patients with recalcitrant maxillary CRS, procedures such as a mega-antrostomy or medial maxillectomy may be needed. When additional exposure to the anterior, lateral, or inferior walls of the maxillary sinus is required, approaches like the pre-lacrimal recess or modified Denker’s procedure may be employed [22]. Similarly, the Draf classification is widely accepted for describing endoscopic approaches to the frontal sinus, though modifications have been proposed [9,21,61]. Minimal disease can be treated by exposing the frontal recess with a full ethmoidectomy (Draf I), whereas a Draf IIa procedure widens the frontal sinus drainage pathway in the frontoethmoidal recess by removing cells medial to the middle turbinate. A Draf IIb procedure extends dissection further medially to the intersinus septum [62,63]. For refractory or extensive disease, or when additional access is required during tumor surgery, a Draf III procedure, which entails complete removal of the intersinus frontal septum with a superior septectomy and anterior drilling of the frontal beak, may be indicated [23].

In proposing a stepwise approach and systematic classification for sphenoid sinus procedures, a key consideration is the naming of each surgical technique. The objective is to establish a rational nomenclature that clearly conveys the intended surgical concept while remaining succinct and memorable [64]. Moreover, in accordance with recommendations to avoid eponyms for disease processes, diagnostic methods, or treatment techniques, we have designated each sphenoidotomy technique with a “type” label [64,65].

The definition of “sphenoidotomy” remains somewhat ambiguous, as it can refer to a range of procedures—including simple dilation, transnasal sphenoidotomy, transethmoidal sphenoidotomy, and more extended approaches that provide wider access for more severe pathologies. Nonetheless, important distinctions exist between these procedures regarding indication, risks, and the extent of surgical dissection. This standardized nomenclature is intended to reduce ambiguity and improve communication between departments, surgeons, and within research contexts. It also helps clarify overlapping terms that might otherwise cause confusion—for example, the term “sphenoid Draf III” is sometimes used imprecisely and may be confused with the “true” Draf III, which specifically describes a frontal sinus procedure [21,23]. Therefore, we propose the term “type III sphenoidotomy” to establish a distinct nomenclature for this particular procedure.

Our classification system encompasses the most commonly performed sphenoidotomies (types I, IIa, IIb, and III), which are routinely used in ESS or FESS to manage prevalent sphenoid sinus pathologies such as CRS, CRS with nasal polyps, or fungal ball sinusitis. In addition, our system incorporates advanced procedures—namely, the TPA (type IV) and sphenoid nasalization (type V)—which, although less commonly included in conventional ESS discussions, are valuable for addressing surgically challenging areas or lesions extending beyond the sphenoid sinus [4,57]. This classification provides a solid foundation for understanding and communicating the diverse approaches available for managing sphenoid sinus lesions.

While this work represents a significant effort to systematically categorize sphenoid surgical approaches, several limitations must be acknowledged. First, our general framework may not capture the nuanced, unpublished techniques that individual surgeons have developed independently, nor can it account for all variations of each procedure. Second, this categorization is based on the opinions of a limited number of sinus surgeons; other practitioners may favor alternative classification systems.

CONCLUSION

We propose a systematic nomenclature for endoscopic sphenoid sinus approaches that is stratified by disease severity, anatomical location, and surgical risks. This standardized nomenclature is intended to enhance inter-surgeon communication and improve academic discourse regarding sphenoid dissection.

HIGHLIGHTS

▪ Unlike maxillary or frontal sinus surgery, no standardized classification currently exists for sphenoid sinus surgery.

▪ We propose a systematic classification of surgical approaches to the sphenoid sinus.

▪ We classified each type of sphenoidotomy based on surgical extent, complexity, and potential complications.

▪ The types are as follows: type I, dilation; type IIa, transnasal; type IIb, transethmoidal; type III; Sphenoid drill-out; type IV, transpterygoid; type V: nasalization.

▪ Through this classification, we aim to promote consistent terminology and interdisciplinary communication.

CONFLICTS OF INTEREST

No potential conflict of interest relevant to this article was reported.

AUTHOR CONTRIBUTIONS

Conceptualization: MJP, JLF, JDS. Methodology: All authors. Validation: All authors. Investigation: All authors. Resources: All authors. Data curation: All authors. Visualization: MJP, JLF, JDS. Supervision: JDS. Project administration: MJP, JLF, JDS. Funding acquisition: JDS. Writing–original draft: MJP, JLF, JDS. Writing–review & editing: MJP, JLF, JDS. All authors read and agreed to the published version of the manuscript.

Fig. 1.

Classification schema depicting the stepwise approach to sphenoidotomy. FESS, functional endoscopic sinus surgery.

Fig. 2.

Type I sphenoidotomy: sphenoid ostial dilation. (A) Axial computed tomography demonstrates moderate left sphenoid sinus opacification. (B) Schematic representation of type I sphenoidotomy, in which the sphenoid ostium is identified at the sphenoethmoidal recess, medial to the superior turbinate (ST). The ST can be gently lateralized, and the sphenoid ostium is subsequently dilated. (C) Postoperative appearance after type I sphenoidotomy.

Fig. 3.

Type IIa sphenoidotomy: transnasal sphenoidotomy (sphenoidotomy without ethmoidectomy). (A) Axial computed tomography demonstrates severe sinus opacification solely confined to the left sphenoid sinus. (B) Illustration of the approach to type IIa sphenoidotomy beginning with inferiorly based flap elevation. (C) Nasal endoscopy at a 1-month postoperative appointment reveals widely opened type IIa sphenoidotomy. ST, superior turbinate.

Fig. 4.

Type IIb sphenoidotomy: transethmoidal sphenoidotomy (sphenoidotomy with ethmoidectomy). (A) Axial computed tomography demonstrates opacification of multiple sinuses to include the bilateral sphenoid sinuses. (B) Schematic illustration of the approach to the face of the sphenoid (blue asterisk) through the opened total ethmoidectomy cavity with extent of surgical dissection. (C) Postoperative endoscopic appearance depicting widely patent type IIb sphenoidotomy. ST, superior turbinate; PE, posterior ethmoid; MS, maxillary sinus; SS, sphenoid sinus; ER, ethmoid roof; LP, lamina papyracea; MT, middle turbinate.

Fig. 5.

Type III sphenoidotomy: sphenoid drill-out. (A) Axial computed tomography demonstrates severe bilateral sphenoid opacification with hyperdense secretions concerning for inspissated fungal debris. The right image shows a separate patient with severe osteoneogenesis of the left sphenoid sinus (yellow arrowhead) that limited the ability to clear disease with type II sphenoidotomy. (B) Schematic illustrations depicting surgical corridors and extent of sphenoid rostral and sphenoid face resection. (C) Postoperative view of a type III sphenoidotomy defect. Blue arrowhead depicts the superior aspect of the septectomy, with a unilateral view of the bilateral sphenoid sinuses (yellow asterisks). ST, superior turbinate.

Fig. 6.

Type IV sphenoidotomy: transpterygoid approach. (A) Computed tomography image of a patient with an encephalocele that herniated the skull base lateral to the foramen rotundum. The yellow asterisk illustrates the lateral recess of the sphenoid sinus. The green arrow highlights the skull base erosion and the source of the encephalocele. (B) Trajectory of resection through the pterygopalatine fossa (PPF) allows for exposure of the lateral sphenoid sinus recess. The contents and bony walls of the PPF (black asterisk) are the main structures that obstructs the lateral sphenoid sinus recess. Note that the lateral dissection through the PPF enables a wider surgical corridor (green area plus red area), compared with when sparing the pterygoid plates in a standard sphenoid sinusotomy (red area only). (C) Intraoperative view of type IV sphenoidotomy, which the encephalocele (green arrow) in the lateral sphenoid sinus recess (yellow asterisk) is fully exposed and visualized after exposing the PPF contents (blue arrowhead), thus enabling a safe repair of the skull base defect in the lateral sphenoid sinus recess. SS, sphenoid sinus; MS, maxillary sinus.

Fig. 7.

Type V sphenoidotomy: sphenoid nasalization. (A) Sagittal computed tomography image of a clear cell carcinoma infiltrating along the sphenoid sinus floor along to the nasopharynx (green arrowheads). (B) Illustration of the type V sphenoidotomy technique. A posterior septectomy has been performed and the intersinus septum carried posteriorly. The sphenoid face will be lowered to the floor of the sphenoid sinus prior to the floor being drilled posteriorly until flush with the superior aspect of the nasopharynx. (C) Postoperative view of type V sphenoidotomy, creating a sphenoid sinus that is fully forming a common cavity with the nasal cavity, and the nasopharynx. Note the location of the sphenoid sinus (SS), small area of residual sphenoid floor (green arrowhead), and the left Eustachian tube opening (white arrow).

Table 1.

Stratification of the nomenclature for various endoscopic sphenoidotomy procedures: suggested clinical scenarios, advantages, and risks

Nomenclature	Surgical procedure	Surgical Indication	Advantage	Disadvantage
Type I	Transnasal dilation of the natural sphenoid ostium without disruption of native mucosa	a. Isolated disease of one or both sphenoid sinuses, or disease in a sphenoid sinus in which balloon dilation of other sinuses is being considered	a. Achieving a “functional” restoration of the sphenoid sinus mucociliary clearance	a. Potentially higher risk of restenosis of the widened sphenoid natural ostium
Sphenoidotomy: sphenoid ostial dilation	Performed via balloon catheterization most commonly; dilation can also be performed with other instrumentation	b. Isolated sphenoid sinus disease in a non-surgical candidate with non-fungal sinus disease	b. Minimally invasive, and potentially less risk of orbital complications	b. Limited ability to observe sinus status postoperatively
		c. Pediatric patients with limited ethmoid sinus disease for whom postoperative debridement may prove difficult	c. Can be performed in an office-based clinical setting without general anesthesia	c. Limited ability to evacuate fungal debris or thicker inspissated secretions
			d. Quicker recovery for patients compared to other methods, decreased need for packing	d. Potential difficulties in cannulation of the natural ostium in the setting of severe inflammation or osteitis
				e. Access may be limited with septal deviation
Type II sphenoidotomies
Type IIa	The sphenoid natural ostium in the SER is identified entered with instrumentation, cold instrumentation or drill in cases of osteitis, followed by the inferomedial widening of the anterior face of the sphenoid	a. Inflammatory conditions of the sphenoid sinus for which limited or no ethmoid dissection is planned	a. Wider surgical corridor for evacuation of inflammatory fungal debris with reduced rates of restenosis when compared to the type I sphenoidotomy	a. This technique results in poorer visibility of the sinus in the postoperative period when compared to more advanced sphenoidotomy techniques
Sphenoidotomy: transnasal sphenoidotomy (sphenoidotomy without ethmoidectomy)	To prevent restenosis of the widened natural os, the exposed bony margins of the widened sphenoid ostium often may be covered with a pedicled posterior septal mucosal flap	b. Simple biopsy of sphenoid lesions	b. Requires limited surgical dissection when compared to more advanced techniques	b. As the principal direction of dissection may be inferior, there is a potential increased risk of injury to the posterior septal branch of the sphenopalatine artery
		c. Marsupialization of simple sphenoid sinus mucoceles	c. May be accomplished under local anesthesia in patients who are able to tolerate the procedure	c. Lateral visibility may be limited by the posterior ethmoids and superior/middle turbinates. This may impair the ability to fully assess or clear more lateral disease within the sinus
		c. Marsupialization of simple sphenoid sinus mucoceles		d. Limited access postoperatively for removal of recurrent debris. Limited options for tumor surveillance
Type Iib	Following a complete anterior and posterior ethmoidectomy, the natural sphenoid ostium or a neo-ostium is identified, and the anterior sphenoid wall can be largely resected	a. Inflammatory sinus disease during which ethmoid dissection is planned	a. Good visibility of the sphenoid face during endoscopic sinus surgery	a. Increased risk of injuring the optic nerve and orbital contents during posterior ethmoidectomy, especially in patients with Onodi cells (posteriorly pneumatized posterior ethmoid sinus)
Sphenoidotomy: transethmoidal sphenoidotomy (sphenoidotomy with ethmoidectomy)		b. Tumors of the sphenoid sinus that can be assessed, resected, and observed via a unilateral sphenoidotomy approach	b. Wider field of exposure with improved access for lateral dissection compared to transnasal approaches	b. Limited ability to perform this surgical dissection as a sole surgical procedure or in cases of isolated sphenoid disease in which additional surgical intervention is not planned
		c. This is the standard approach for the endoscopic sphenoidotomy during routine pan-sinus endoscopic sinus surgery	c. Limited need for inferior sphenoid dissection, potentially minimizing risks to the posterior septal branch of the sphenopalatine artery
			d. Allows creation of a larger sphenoidotomy, which may minimize the risk of postoperative stenosis
Type III	Bilateral type II sphenoidotomy is performed. Generally, the authors recommend performing a type IIb sphenoidotomy in at least one sinus	a. Bilateral inflammatory sphenoid disease or unilateral sphenoid disease recalcitrant to prior type II sphenoidotomies	a. Decreased risk of stenosis compared to previous sphenoidotomy types	a. Extended surgical dissection time, particularly in severe osteitis
Sphenoidotomy: sphenoid drill-out	A posterior septal flap can be created if desired and sphenoid disease allows and the mucosa overlying the face of the sphenoid can be elevated inferiorly and preserved	b. Severe osteitis of the sphenoid sinus	b. Allows extended visualization of both sinuses, particularly along the midline	b. Increased risk of damage to the posterior septal branches of the sphenopalatine artery during dissection and drilling
	A posterior septectomy is performed, followed by exposure and resection of the sphenoid rostrum to the level of the sphenoid floor. The intersinus septum is then drilled posteriorly until flush or near-flush with the posterior wall of the sphenoid sinus	c. Tumor resection requiring extended exposure of the sphenoid sinus for resection or surveillance	c. Ability to perform bi-nostril dissection within the sphenoid sinus	c. Longer patient recovery with the need for remucosalization of the bone of the sphenoid floor and rostrum
		d. Resection of sellar, suprasellar, clival, tuberculum sellae, cavernous sinus, orbital apex, petrous apex, or planum sphenoidale lesions through extended approaches		d. Inability to fully expose and manipulate the lateral recess, especially when the lesion is located at the base of the lateral recess of the sphenoid sinus
	The surgical extent can be modified depending on pathologic indication; wider lateral and superior dissection may be required for sellar or transtubercular lesions. Similarly, inferior dissection may be necessary for clival lesions. Far lateral dissection may be required for cavernous sinus or orbital apex disease			e. Increased risk of olfactory dysfunction as resection may involve the bilateral superior turbinates and posterior septum, particularly if dissection is carried too superiorly
Type IV	Completion of ipsilateral wide maxillary antrostomy, complete ethmoidectomy with complete exposure of the lamina papyracea, and type IIb sphenoidotomy or type III sphenoidotomy	a. Cerebrospinal fluid leaks of the lateral sphenoid sinus recess	a. Provides excellent visualization of the lateral sphenoid sinus recess	a. Risk of neurological complications with the possibility of injuring the maxillary nerve (V2), greater palatine nerve, Vidian nerve and/or pterygopalatine ganglia
Sphenoidotomy: transpterygoid approach	Maxillary dissection is carried to the posterior wall of the maxillary sinus, and the pterygopalatine fossa is entered at the sphenopalatine foramen. The posterior face of the sphenoid is removed, exposing the entire pterygopalatine fossa	b. Management of the meningoceles or meningoencephaloceles that herniated through the lateral recess of the sphenoid sinus	b. Reduced comorbidities and surgical time compared with the transtemporal external approach	b. Risk of significant intraoperative and postoperative bleeding by the internal maxillary artery or its branches
	The contents of the pterygopalatine fossa can be removed or displaced inferolaterally, exposing the lateral face of the sphenoid sinus. The sphenoid sinus can then be opened laterally, exposing the lateral sphenoid sinus recess. The Vidian nerve and sphenopalatine artery may need to be divided for further lateral exposure	c. Malignant tumors, neoplastic lesions, invasive fungal rhinosinusitis invading or involving the lateral sphenoid sinus recess		c. Risks of impairing the mastication function or trismus due to a possible injury of pterygoid muscles
				d. Technically complex surgical dissection with increased operative time
Type V	Completion of an ipsilateral type IIb sphenoidotomy or a type III sphenoidotomy is performed	a. Refractory inflammatory sinus disease to other surgical interventions	a. Enables completely dependent drainage of the sphenoid sinus, bypassing the need for mucociliary clearance	a. Injury to the sphenopalatine and palatovaginal arteries is possible during inferior and lateral resection of the sphenoid floor
Sphenoidotomy: sphenoid sinus nasalization	An inferiorly-based mucosal flap can be elevated if the disease process allows. The superior horizontal incision is made at the level of the sphenoid ostium and connected to vertical incisions along the lateral face of the sphenoid sinus and along the septal mucosa. Vertical incisions are extended inferiorly to the superior aspect of the nasopharynx	b. May be considered if completely dependent drainage of the sphenoid sinus is necessary, as in primary ciliary dyskinesia or cystic fibrosis	b. Allows complete visualization and exposure of the sphenoid sinus; useful when postoperative endoscopic surveillance is of importance	b. Increased risk of intraoperative and postoperative bleeding during drill-out of the marrow-rich bone of the clivus and sphenoid floor. This bleeding can be difficult to control and may be difficult to pack given posterior location within the nasopharynx
Sphenoidotomy: sphenoid sinus nasalization	The floor of the sphenoid sinus is resected posteriorly until flush with the nasopharynx	c. Resection of tumors involving the floor of the sphenoid sinus or superior nasopharynx or disease processes requiring extensive surgical resection such as invasive fungal sinusitis		c. Requires extensive remucosalization of the bone of the clivus, posterior septum, and lateral sphenoid walls

SER, sphenoethmoidal recess.

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