Endoscopic Transpterygoid Approach Research Articles

Endoscopic Multiport Approach for Exenteration of the Infratemporal Fossa.

To demonstrate anatomic relationships pertinent to the endoscopic multiport approach to the infratemporal fossa (ITF). Discuss advantages and limitations of each individual approach. Cadaveric study. Endoscopic and endoscopic-assisted endonasal transpterygoid, sublabial transmaxillary, endoscopic transorbital, and endoscopic transoral approaches to accessing the ITF were completed in five silicone-injected fresh cadaveric specimens (10 sides) with the assistance of 0, 30, and 450 rods-lens endoscopes. Image guidance was used to confirm and document the anatomical relationships encountered in each approach. The endonasal endoscopic transpterygoid approach provides better visualization and more direct exposure to median structures. Endoscopic-assisted sublabial transmaxillary approach enhances the field of exposure, angle of attack, and ease of instrumentation to the lateral part of the ITF. Endoscopic-assisted transorbital approach via the inferior orbital fissure provided cephalic and anterior access. Endoscopic-assisted transoral approach complements the access to lesions extending inferior to the hard palate or far lateral to the mandibular condyle. A combination of minimal access infratemporal approaches can provide adequate exposure of the entire ITF while avoiding some of the morbidity associated with open approaches. NA Laryngoscope, 133:1367-1374, 2023.

Endoscopic Transpterygoid Corridor for Petroclival Tumors: Case Series and Technical Nuances.

The petroclival area is a technically challenging region to operate owing to the proximity of the internal carotid artery (ICA) and the need to obtain gross total excision of tumors in this area as they are often resistant to radiotherapy. We present our experience with the endonasal endoscopic transpterygoid approach in managing tumors of the petroclival region and discuss various operative nuances for safer resection. A retrospective study of all consecutive cases of lesions occupying the petroclival region that were operated via endonasal endoscopic transpterygoid approach at our center between January 2016 and December 2021 was performed. The study included 14 cases of lesions occupying the petroclival region. Gross total resection by intraoperative observation was achieved in 10 patients, near total decompression was performed in two patients, and the remaining two patients underwent marsupialization of lesion. Postoperatively, one patient had right Lower motor neuron (LMN) facial nerve palsy and one patient required surgery for Cerebrospinal fluid (CSF) rhinorrhea on postoperative day 8. The mean duration of follow-up was 13.8 ± 16.6 months (range: 2-59 months). Four of six patients with visual symptoms on presentation reported improvement in vision, and the other two patients had a stable vision on follow-up. Two patients received radiotherapy postsurgery. No mortality was noted. The extended endonasal endoscopic transpterygoid approach can be safely and efficiently used for petroclival lesions. Very sound knowledge of anatomical relationship, use of intraoperative image guidance to avoid injury to ICA, and multilayer reconstruction with a vascularized nasoseptal flap are required to optimize the clinical outcome.

Extended Endoscopic Endonasal Approach for a Giant Parasellar Epidermoid Cyst.

Epidermoid cysts are rare lesions which typically grow slowly. For this reason, these lesions are usually discovered when they are already very large. The parasellar location is no exception to this rule and may involve the cavernous sinus or the Meckel cave. We present a 34-year-old female patient without past medical history who was admitted in our tertiary referral center for episodes of diplopia in the right lateral gaze and right trigeminal dysesthesias. Brain magnetic resonance imaging (MRI) showed a large right parasellar mass with mixed intensity signal on the T1 and T2 sequences, without contrast enhancement and a typical hypersignal intensity on diffusion-weighted sequences evoking an epidermoid cyst. We discuss the radiologic criteria which differentiate the lesions originating in the cavernous sinus from those of the Meckel cave ( Figs. 1 and 2 ). Parasellar tumors may be approached through classical transcranial approaches such the epidural temporopolar or the subtemporal approach which involve a significant degree of brain retraction. The last decade witnessed the advent of extended endonasal approaches which offer an interesting alternative and avoid the manipulation of the brain. We used the endoscopic transpterygoid approach in our patient and we were able to achieve an excellent clinical and radiological result. We discuss the nuances of the technique and present the surgical steps of the procedure ( Figs. 3 and 4 ). The endoscopic endonasal approach represents an excellent therapeutic option for parasellar lesions. A thorough knowledge of the anatomy and experience with endoscopic techniques are obvious prerequisite. The link to the video can be found at: https://youtu.be/QonSvHrCwOU .

Simplifying Access to the Lateral Sphenoid Recess: A Modification of the Transpterygoid Approach.

Meningoencephaloceles originating in the lateral recess of the sphenoid sinus can be difficult to access. Historically, the endoscopic transpterygoid approach was advocated, which carries additional morbidity given the dissection of the pterygopalatine fossa (PPF) contents to provide a direct line approach to the defect. Given our increased facility with angled endoscopes and instrumentation, we now approach this region in a less invasive manner. We describe the endoscopic modified transpterygoid approach (MTPA), a quicker approach to the lateral sphenoid recess which preserves the PPF contents through a single nostril corridor. In the MTPA, the face of the sphenoid and anterior junction of the pterygoid plates are removed, allowing for mobilization of the PPF contents with the periosteum intact. Angled instrumentation is then used to resect the meningoencephalocele and repair the skull base defect in the lateral recess. If increased exposure is needed, this can be gained by sacrificing the sphenopalatine artery and even the vidian nerve, although this is rarely required. The MTPA obviates the need for PPF dissection and simplifies access to the lateral sphenoid recess while minimizing postoperative morbidity. This approach should be considered for accessing meningoencephaloceles and other benign lesions in this challenging location.

Endoscopic management of lateral sphenoid cerebrospinal fluid leaks: Identifying a radiographic parameter for surgical planning.

ObjectiveRepair of cerebrospinal fluid (CSF) leaks of the lateral recess of the sphenoid (LRS) sinus can be challenging to accomplish via an endoscopic transphenoidal approach. The endoscopic transpterygoid approach can improve surgical access to the lateral recess but requires more extensive surgical dissection. We review our experience with LRS CSF leak repair via both techniques to determine whether preoperative radiologic data can help predict the most appropriate surgical approach.MethodsElectronic medical records of patients with LRS CSF leaks were retrospectively reviewed at a single tertiary referral center. Radiographic measurements from preoperative computed tomography images were reviewed.ResultsTwenty‐two LRS CSF leaks were identified. The transphenoidal and transpterygoid approach were used in 6 (27.3%) and 16 (72.7%) cases, respectively.The mean vidian canal to foramen rotundum angle of the repairs accessed transphenoidally as compared to the transptyergoid approach were not significantly different (41.93° ±10.91, 40.72° ±19.49, respectively; P = .63). However, the mean volume of the LRS accessed by the transpterygoid approach was significantly greater compared to those accessed through the transphenoidal approach (0.97 cm3 ± 0.48, 0.39 cm3 ± 0.40, respectively; P = .04). A LRS volume of 0.400 cm3 or greater predicted the use of the transpterygoid approach with 93.3% sensitivity and 60.0% specificity.ConclusionThis study demonstrated that LRS CSF leaks that necessitated repair by the transpterygoid approach, rather than transphenoidal approach, were in the context of significantly larger lateral recess. Assessment of the LRS volume is a quantifiable parameter to aid in preoperative surgical planning.Level of EvidenceLevel 4.

Stepwise Surgical Corridors for Endoscopic Transpterygoid Approach

Stepwise Surgical Corridors for Endoscopic Transpterygoid Approach

Surgical excision of trigeminal (V3) schwannoma through endoscopic transpterygoid approach

Background:Endoscopic endonasal transpterygoid (EET) approach is well suited for trigeminal schwannomas.Case Description:A 25-year-old female presented with the right hemifacial pain for 1 month. Examination revealed mild sensory loss to both touch and pain in the right V2 and V3 dermatomal distribution. On magnetic resonance imaging, a well-defined extra-axial lesion was seen in the right infratemporal fossa extending intracranially, widening the foramen ovale. Erosion of the lateral pterygoid plate was evident on computed tomography. Diagnosis of a trigeminal schwannoma was made and excision through endoscopic transnasal transpterygoid approach was planned. After adequate nasal decongestion, lateralization of the inferior turbinate followed by medialization of middle turbinate done to expose the posterior part of the lateral nasal wall. Sphenopalatine foramen was visualized and the branches of the sphenopalatine artery to turbinate were coagulated followed by partial inferior and middle turbinectomy. Next, antegrade uncinectomy, bullectomy, and middle meatal antrostomy performed. Anterior and posterior ethmoidectomy was done to gain access to the sphenoid sinus. Medial maxillectomy done, posterior maxillary sinus wall exposed and drilled to reach infratemporal fossa harboring the tumor. The lateral recess was further exposed to visualize the vidian and maxillary nerves. Palatine bone and pterygoid body along with the medial pterygoid plate were completely drilled to expose the tumor capsule, which was gently dissected off. Complete tumor excision was performed uneventfully.Conclusion:EET provides a good oncological and functional outcome. With a lesser risk of surgical morbidities, it is an excellent alternative to conventional skull base approaches to trigeminal schwannomas in the modern era.

Morbidities Associated with the Endoscopic Transnasal Transpterygoid Approach: Focusing on Postoperative Sequelae

Although the endoscopic transpterygoid approach has been popularized, there are no studies about anatomy-specific morbidities of this approach. The objective of this study is to investigate the surgical morbidities associated with the endoscopic transpterygoid approach for resection of anatomic structures. A retrospective analysis was carried out of prospectively collected data of patients who underwent the endoscopic transpterygoid approach for skull base tumor by a single ear nose and throat surgeon in a tertiary-care center from November 2013 to January 2019. Postoperative patient symptom prevalence associated with surgical findings and SNOT-22 (Sino-Nasal Outcome Test-22) score were included in the analysis. Thirty-seven consecutive patients were enrolled. The mean follow-up period was 12.4 months (range, 1-39 months). Twenty-six (70.3%) vidian nerves were sacrificed, but only 38.5% of those patients (10/26) reported mild dry eye symptoms. Fourteen nasolacrimal ducts (37.8%) were resected, with only 1 patient (7.1%) who had undergone previous radiation therapy reporting transient epiphora. SNOT-22 scores before and after surgery did not present statistical difference in inferior turbinate sacrifice group and preservation group. Sacrifice of sinonasal structures such as the inferior turbinate or vidian nerve is sometimes inevitable for safe tumor resection with the endoscopic transpterygoid approach. Subjective symptoms were not apparent in most patients, despite the structural sacrifice.

Endoscopic-Assisted Lateral Corridor to the Infratemporal Fossa: Proposal and Quantitative Comparison to the Endoscopic Transpterygoid Approach.

Objective This study was aimed to propose an expanded endoscopic-assisted lateral approach to the infratemporal fossa (ITF) and compare its area of exposure and surgical freedom with the endoscopic endonasal transptergyoid approach (EETA). Methods Anatomical dissections were performed in five cadaver heads (10 sides). The ITF was first examined through the endoscopically assisted lateral corridor, herein referred to as the endoscopic-assisted transtemporal fossa approach (TTFA). After that, the EETA was performed and coupled with two sequential maxillary procedures (medial maxillectomy [MM], and endoscopic-assisted Denker's approach [DA]). Using the stereotactic neuronavigation, measurements of the area of exposure and surgical freedom at the foramen ovale were determined for the previously mentioned approaches. Results Bimanual exploration of the ITF through the endoscopic-assisted lateral approach was achieved in all specimens. The DA (729 ± 49 mm 2 ) provided a larger area of exposure than MM (568 ± 46 mm 2 ; p < 0.0001). However, areas of exposure were similar between the DA and the TTFA (677 ± 35 mm 2 ; p = 0.09). The surgical freedom offered by the TTFA (109.3 ± 19 cm 2 ) was much greater than the DA (24.7 ± 4.8 cm 2 ; p < 0.0001), and the MM (15.2 ± 3.2 cm 2 , p < 0.0001). Conclusion The study demonstrates the feasibility of the proposed approach to provide direct access to the extreme extensions of the ITF. The lateral corridor offers an ideal working area in the posterior compartment of the ITF without crossing over important neurovascular structures. The new technique may be used alone in selected primary ITF lesions or in combination with endonasal approaches in pathologies spreading laterally from the nose or nasopharynx.

Endoscopic transpterygoid approach for resection of trigeminal neurotropic melanoma: Case report and technical note

BackgroundThe endoscopic transpterygoid approach to Meckel's cave is an established technique for resection of trigeminal schwannomas. Modern endoscopes provide excellent intraoperative visualization of anatomic structures and relevant pathology while the minimally-invasive nature of the procedure allows for rapid postoperative recovery. Neurotropic melanoma is a rare clinical entity that often involves the head and neck and can lead to cranial neuropathies when nerve invasion occurs. Pathological diagnosis of this lesion can be challenging due to its rarity and lack of classic melanoma markers such as Melan-A and HMB-45. Case descriptionIn this article, the authors describe the endoscopic transpterygoid approach to a neurotropic melanoma involving the maxillary and infraorbital nerves. To our knowledge, this is the first use of this surgical approach for resection of neurotropic melanoma. ConclusionsEndoscopic approaches to the trigeminal nerve allow for safe and effective resection of these lesions. However, a strong understanding of the microsurgical anatomy is necessary prior to such an undertaking.

Endoscopic Endonasal Transpterygoid Approach to Sphenoid Sinus Lateral Recess Defects.

Background Lesions affecting sphenoid sinus lateral recess (SSLR) are difficult to visualize and manipulate through the transnasal routes, especially when the sinus is highly pneumatized. External approaches to this area involve extensive surgery and are associated with significant morbidity. The aims of this study are to present our experience with the endoscopic transpterygoid approach as a method for approaching lesions of the SSLR and to evaluate the outcomes of this procedure. Methods Clinical charts of patients who had lesions in the SSLR and who were treated at our institution from September 1998 to June 2018 were retrospectively reviewed. All these patients were managed by the endoscopic endonasal transpterygoid approach. Results Thirty-nine patients were identified. No cerebrospinal fluid leak recurrences were observed during follow-up (range: 1-19.7 years; median: 2.3 years). Hypoesthesia (temporary, 1; persistent, 4) in the region innervated by the maxillary branch of the trigeminal nerve was detected in five (12.8%) patients, while symptoms due to the Vidian nerve damage (dry eye, 3; dry nasal mucosa, 1) were present in four (10%) patients. Conclusions Although the endoscopic endonasal transpterygoid approach is an excellent corridor for dealing with lesions of the SSLR, limited rate of neurologic and lacrimal complications was observed. Potential morbidity of the intervention should be discussed during preoperative counselling.

Surgical salvage of recurrent T3 nasopharyngeal carcinoma: Prognostic significance of clivus, maxillary, temporal and sphenoid bone invasion

BackgroundTo study the efficacy of surgery for recurrent T3 nasopharyngeal carcinoma (NPC) and to determine the prognostic significance of various skull base bone invasion. MethodRetrospective view of the surgical outcome for recurrent T3 NPC. Kaplan Meier and log rank tests were used to determine the 5-year overall and disease specific survival. Multivariate analysis was used to identify significant independent prognostic factors that affect the surgical outcome. ResultsBetween 1990 and 2017, 208 patients with recurrent T3 NPC were recruited. Salvage surgery was performed via the endoscopic endonasal approach (n = 22, 10.6%), endoscopic transpterygoid approach (n = 63, 30.3%) and the maxillary swing approach (n = 123, 59.1%). Thirty-eight (18.3%) patients required vascular bypass. The skull base bone involved by the tumours included: maxillary sinus (n = 13), clivus (n = 36), pterygoid process (n = 61), sphenoid sinus (n = 30), petrous part of the temporal bone (n = 42) and a combination of the above (n = 26). The mean follow-up duration was 41.7 months. Multivariate analysis identified tumours involving with both cortexes of the clivus and the lateral wall of the sphenoid sinus, as well as positive bone resection margins as the significant independent prognostic factors for surgical outcome. ConclusionOutcome of surgical salvage is significantly worse for tumours that involve multiple bones at the skull base, particularly when both cortexes of the clivus and the lateral wall of the sphenoid sinus are invaded. Indication of aggressive surgery in such circumstances is controversial.

Clinical implications of transpterygoid approach to mandibular nerve

BackgroundThe endonasal transpterygoid approach has been very popular as a standard approach to the pterygopalatine and infratemporal fossa. However, its implications actually extend beyond these regions to include access to the middle cranial fossa and parapharyngeal space.ObjectiveThe aim was to illustrate the anatomical landmarks of the endoscopic transpterygoid approach especially the mandibular nerve and clinical implication of this approach through illustrated case presentation.Materials and methodsA cadaveric study was performed on three cadaveric adult specimens. Endoscopic medial maxillectomy, Sturman Canefield approach, and completion of transpterygoid approach were done to visualize the different anatomical landmarks, especially the mandibular nerve. An example of clinical application of transpterygoid approach is an illustrated case to biopsy a perineural spread of squamous cell cancer along the mandibular nerve in the lateral wall of cavernous sinus.ConclusionEndoscopic transpterygoid approach is very useful to resect most of benign and some malignant tumors that involve the infratemporal fossa and middle cranial fossa. Good understanding of the V3 anatomy helps in the resection of tumors extending to the infratemporal fossa and poststyloid parapharyngeal space.

Cavernous Sinus and Parasellar Region: An Endoscopic Endonasal Anatomic Cadaver Dissection.

The aim of this study was to investigate the neurovascular structures of the cavernous sinus with the endonasal endoscopic transpterygoid approach on fresh human cadavers. Additionally, the course of internal carotid artery (ICA) and relevant anatomy was thoroughly investigated to refine the anatomical landmarks, exposure difficulties, potential complications, and limitations using the endonasal endoscopic technique. This study was carried out at an otolaryngology department of a tertiary medical center between June 2014 and June 2015. The surgical dissection was performed on 10 fresh human cadaver specimens using paranasal sinus and skull base endoscopic instruments. Cavernous sinuses and parasellar area were explored via an endoscopic endonasal transpterygoid approach. Dehiscence was present in 5 (25%) cavernous ICAs. Projection of the cavernous ICA on the whole lateral sphenoid wall was prominent in 6 (%30) sphenoid sinuses. Anterior curve was prominent in 12 (60%) cavernous ICAs, whereas posterior was prominent in 7 (35%). Mean distance between the lateral wall of eustachian tube orifice and petrous ICA was 19.50 ± 1.05 mm (range 18-22 mm). Cranial nerves of the cavernous sinus showed no variation. Control of the ICA is critical during the endonasal endoscopic approach to the cavernous sinus and skull base. The vidian nerve is a reliable and important landmark to the petrous ICA in the transpterygoid approach. Dissection of the eustachian tube and its relation to the ICA has to be kept in mind during nasopharyngeal surgery.

Endoscopic endonasal approach to the vidian nerve and its relation to the surrounding structures: an anatomic cadaver study.

The aim of this study was to investigate the neurovascular structures and their relevant anatomy with the endonasal endoscopic transpterygoid approach on fresh human cadavers. In addition, the relationship between the vidian nerve, ICA and surrounding structures were investigated METHODS: This study was carried out at an otolaryngology department of a tertiary medical center between June 2014 and June 2015. Ten fresh human cadavers were included in this study. Pterygopalatine fossa was explored via an endoscopic endonasal transpterygoid approach. Same surgical dissection procedures were performed on all cadavers: maxillary antrostomy, anterior and posterior ethmoidectomy, sphenoidotomy, transpterygoid pterygopalatine fossa and vidian canal dissection. Mean distance between the anterior nasal spine and ethmoidal crest was 60.35 ± 1.31 mm (range 59-64 mm). Mean distance between the sphenopalatine foramen and superior border of choana was 18.30 ± 1.38 mm (range 17-22 mm). Mean distance between the vidian canal and sphenopalatine foramen was 6.30 ± 0.47 mm (range 5.5-7 mm). Mean distance between the vidian canal and anterior nasal spine was 64.6 ± 1.71 mm (range 62-67 mm). Foramen rotundum was located superior lateral to the vidian canal in all specimens. Mean distance between foramen rotundum and vidian canal was 9.45 ± 0.60 mm (range 8.5-10.5 mm). Course of the greater palatine nerve was always medial to the descending palatine artery. The mean length of the vidian nerve from the petrous ICA to the point the nerve exits the vidian canal (vidian canal length) was 17.90 ± 1.59 mm (range 16-20 mm). The distances between the vidian canal and surrounding neurovascular structures would help the skull base surgeon in this narrow and complex area.

Experience of treating patients with lateral sphenoid sinus recess CSF leak

The study purpose was to analyze our own experience in treating patients with CSF leak and meningoencephalocele in the lateral sphenoid sinus recess and, based on the obtained results, develop an algorithm for the treatment of this pathology. We retrospectively reviewed a series of 89 patients with CSF leak and meningoencephalocele in the lateral sphenoid sinus recess who were treated at the Burdenko Neurosurgical Institute in the period between 2001 and 2017. The demographic characteristics of patients, clinical data, and aspects of surgical treatment were analyzed. Treatment outcomes were assessed based on analysis of recurrences and postoperative complications. The obtained data were compared to the literature data. In the series of 89 patients with CSF leak and meningoencephalocele in the lateral sphenoid sinus recess, the mean age was 49 years. Surgery through the transsphenoid approach was performed in 89 (74%) patients. There were 25 (28%) recurrences in this group. Nine (7%) patients underwent repair of a complex skull base defect using the transethmoidal approach; there were 3 (33%) recurrences. The transpterygoid approach was used in 22 (17%) patients; there were 3 (14%) recurrences in this group. Endoscopic endonasal repair is an effective technique for treating complex skull base defects in the lateral sphenoid sinus recess. The choice of an approach to the defect depends on the degree of pneumatization of the sphenoid sinus, surgeon's experience, and availability of the necessary equipment and tools. The endoscopic transpterygoid approach is advisable to use in cases of excessive pneumatisation of the sinus with developed lateral processes and recurrent nasal CSF leak. This enables visualization of the defect edges in this hard-to-reach area and adequate repair.

Endoscopic transpterygoid approach to the skull base lesions

Endoscopic transpterygoid approach to the skull base lesions

Spontaneous CSF rhinorrhea from the trigeminal canal in an adolescent

We report a case of a seventeen-year old, healthy, non-obese young woman who presented with retro-orbital headaches and metallictasting, left-sided rhinorrhea. Computed tomography revealed a defect along the medial wall of the canal of V2 within a well-pneumatized lateral recess of the left sphenoid sinus. Prior imaging obtained 4 years earlier in the context of nasal trauma showed no such defect - thus lending support for the arachnoid granulation hypothesis of spontaneous CSF leaks from the sphenoid sinus. We perform a literature review and describe a successful repair through an endoscopic transpterygoid approach, which allowed for resolution of symptoms with minimal postoperative morbidity.

The Pedicled Buccal Fat Pad: Anatomical Study of the New Flap for Skull Base Defect Reconstruction After Endoscopic Endonasal Transpterygoid Surgery.

Objectives To evaluate the efficacy and safety of using a buccal fat pad for endoscopic skull base defect reconstruction. Design Descriptive anatomical study with an illustrative case presentation. Setting Anatomical study was performed on 12 fresh human cadaver specimens with injected arteries (24 sides). Internal carotid artery was exposed in the coronal plane via the endoscopic transpterygoid approach. The pedicled buccal fat pad was used for reconstruction. Participants: 12 human cadaver head specimens; one patient operated using the proposed technique. Main outcome measures: Proximity of the buccal fat pad flap to the defect, compliance of the flap, comfort and safety of harvesting procedure, and compatibility with the Hadad-Bassagasteguy nasoseptal flap. Results: Harvesting procedure was performed using anterior transmaxillary corridor. The pedicled buccal fat pad flap can be used to pack the sphenoid sinus or cover the internal carotid artery from cavernous to upper parapharyngeal segment. Conclusion The buccal fat pad can be safely harvested through the same approach without external incisions and is compliant enough to conform to the skull base defect. The proposed pedicled flap can replace free abdominal fat in central skull base reconstruction. The volume of the buccal fat pad allows obliteration of the sphenoid sinus or upper parapharyngeal space.

Radiographic characterization of the retroantral ethmoid cell.

The retroantral ethmoid cell (RAEC) is defined as a posterior ethmoid cell that pneumatizes inferolaterally behind the posterior wall of the maxillary sinus. The RAEC can present a challenge to otolaryngologists during endoscopic ethmoidectomy due to its concealed location. It is also encountered during the endoscopic transpterygoid approach to the skull base, which requires dissection behind the posterior wall of the maxillary sinus. Because the RAEC is not described in the literature, this study aims to better characterize this anatomic variant. This is a retrospective review of 58 consecutive patients who underwent revision functional endoscopic sinus surgery (FESS) within a 2-year period at a tertiary referral center. Sinus computed tomography (CT) scans for this cohort (116 sides total) were reviewed independently by 3 authors to determine the incidence of the RAEC and the degree of surgical dissection during prior surgery. Of the 116 sides included in the study, RAEC was identified in 19 (16%). Furthermore, 14 of 19 (74%) cells were diseased with evidence mucosal thickening or neo-osteogenesis. Of the 12 sides with RAEC that had evidence of previous posterior ethmoidectomy, 4 (33%) cells were not opened, 6 (50%) were partially opened, and only 2 (17%) were completely opened. This study demonstrates the relatively high prevalence of the RAEC in our patient population. The majority of RAECs showed both evidence of disease and that they were not completely opened during previous surgery. Recognition of this anatomic entity may allow for more thorough ethmoidectomy.