Ethmoid Bulla Research Articles

New Perspectives in the Etiology of Chronic Rhinosinusitis-Haller Cells.

Background and Objectives: Haller Cells (HCs) represent the abnormal migration of ethmoid cells that are located below the ethmoid bulla at the level of the upper wall of the maxillary sinus. Through their placement, the cells can exert a mass effect on the infundibulum of the maxillary sinus. The aim of our study is to investigate the prevalence of Haller cells in the Romanian population and to evaluate the relationship between this anatomical variation and chronic rhinosinusitis. Secondly, we want to morphometrically evaluate the impact of Haller cells' presence in the drainage paths of the maxillary sinuses. Materials and Methods: We conducted a randomised retrospective study that included 255 consecutive multi-detector computed tomography (MDCT) scans of the head. To carry out a comparative evaluation of the association of Haller cells with chronic rhinosinusitis, we divided the patients into two subgroups, a seasonal-based sample, between November 2022 and January 2023, and June 2023 and August 2023, respectively. We report the mean ± standard deviation for the continuous variables. To compare the results, we used the following statistical tests: a chi-squared test and a paired Student's t-test (one-tail). Results: Our study identified a high prevalence of Haller cells, namely in 128 out of 255 patients (50.2%). There were no statistically significant associations between the presence of HCs and the age and the gender of the sample, respectively. The unilocular morphotype predominates in unilateral shapes and in bilateral shapes as well (p = 0.002). Our study identified the correlation between the Haller cells and the chronic rhinosinusitis in both research samples: "Winter group" and "Summer group" (p = 0.0002 and p = 0.0001, respectively). Conclusions: It was determined that for 40 out of 42 patients, the presence of HCs changes the morphometric pattern of the infundibular maxillary sinus.

Approach to frontal sinus via five frontal sinus drainage pathways.

This study aimed to validate a method for successful frontal sinus surgery. The method classifies the frontal sinus drainage pathway (FSDP) into five categories based on three bony walls of the anterior ethmoid sinus, including the uncinate process (UP), accessory uncinate process (UPa), and basal lamella of the ethmoid bulla (BLEB), which was tested in actual surgical procedures. This study analyzed 53 sides of 48 patients who underwent frontal sinus surgery between October 2022 and March 2023. We classified the FSDPs using preoperative computed tomography (CT) and multiplanar reconstruction (MPR). During surgeries for FSDPs located anterior to the BLEB, we used a two-step method involving resection of the turbinal UP, followed by upward resection from the lower edge of the ethmoidal UP. For FSDPs located posterior to the BLEB, we resected the BLEB at the superior semilunar recess. We confirmed the origin of each of the five types of FSDP during surgery. These origins, which were located at the lowest part of the anterior ethmoid, could be identified in the early stages of ethmoid sinus surgery before proceeding to the frontal recess area. The origins of the five types of FSDP, classified based on the bony walls, can be clearly and accurately identified during surgery. This provides a reliable method for preoperatively predicting and locating the inferior end of the FSDP (origin), without extensive manipulation of the cells formed in the frontal fossa.

Semi-Automated Virtual Endoscopy of the Frontal Recess.

Virtual endoscopy (VE) is the computer-based reprocessing of diagnostic imaging to simulate endoscopy of an anatomic region of interest. VE of the Frontal Sinus Outflow Tract (FSOT) may assist surgical planning and education. VE was performed on 16 normal sinus computed tomography (CT) scans for a total of 32 sides using the "path-to-target" tool on the TruDi surgical navigation system (ver. 2.3; Acclarent, Irving, CA, USA). To aid orientation during VE, planning points were placed on the middle turbinate, ethmoidal bulla, and skull base. The VE representation of anatomy and FSOT accuracy was manually confirmed by reviewing the corresponding orthogonal CT images and comparing them to the computed pathway. Of the 32 sides, the software successfully calculated the FSOT in 22 sides (69%). Of those 22 sides, the calculated FSOT, depicted in the VE sequences accurately represented the FSOT. Among sides with an accurately calculated FSOT, the VE sequences depicted a "fly-through" from a starting point in the middle meatus around various frontal recess cells to the end point in the frontal sinus. This pilot study demonstrates that software-generated VE of the FSOT is indeed feasible but requires confirmation by the surgeon for accuracy. Instances in which the software did not achieve its objective may drive further refinements of the protocol. VE of the FSOT should be explored as a tool for preoperative planning and surgical education.

The Usefulness of YouTube Videos Related to Endoscopic Sinus Surgery for Surgical Residents

Abstract Objective The use of online teaching modalities to supplement surgical learning has increased recently, demonstrating promising results. Previous studies have analyzed the value and usefulness of YouTube as an educational source to learners, including teaching surgical skills to Otolaryngology–Head and Neck Surgery (OHNS) trainees. YouTube videos on endoscopic sinus surgery (ESS) still need to be explored as ESS remains a common, yet challenging surgery that OHNS residents encounter regularly. This study aimed to objectively evaluate the usefulness of YouTube videos on ESS for surgical education. Design YouTube was searched using the following keywords: “uncinectomy,” “maxillary antrostomy,” “anterior ethmoidectomy,” and “ethmoid bulla resection.” These represent the initial ESS steps residents learn. Each video was assessed for eligibility by two independent reviewers. Outcome Measures The LAParoscopic surgery Video Educational Guidelines (LAP-VEGaS) and ESS-specific criteria were used to assess educational quality. Video popularity index (VPI) was used to calculate video popularity. Results Of the 38 videos that met inclusion criteria, the average LAP-VEGaS score was 6.59 (± ) 3.23 standard deviation. Most videos were designated low quality. There was a weak positive correlation between whether a video included ESS-specific criteria and LAP-VEGaS score (r = 0.269, p = 0.102). There was a significant positive correlation between VPI and LAP-VEGaS scores (r = 0.497, p = 0.003). Conclusions Overall, the quality of included videos was poor. OHNS residents should not rely solely or primarily on YouTube videos to learn surgical skills relevant to ESS. To maximize potential of online teaching, high-quality videos should be used to compliment other methods of teaching.

Exploring the frontal recess: Specimens, endoscopy, and CT perspectives

Abstract The frontal sinus, situated between the external and internal plates of the frontal bone, posterior to the brow ridges, is the most superior and complex structure within the paranasal sinuses. The frontal sinus outflow tract encompasses two parts: the frontal ostium superiorly and the frontal recess inferiorly, collectively forming the frontal sinus drainage pathway. The frontal recess represents the most anterosuperior portion of the ethmoid. Pneumatization of this area can extend from the agger nasi cell anteriorly to the ethmoidal bulla posteriorly. This recess is bounded by the orbital plate of the ethmoid laterally and the middle nasal concha (‘middle turbinate’) medially. The detailed understanding of frontal sinus anatomy is indispensable for medical professionals, including surgeons, otolaryngologists, rhinologists, and radio-logists. The frontal recess is clinically important, especially in the diagnosis and management of various medical conditions, particularly sinusitis. Surgeons often need to navigate this intricate area. Radiological imaging, such as computed tomography (CT) scans, is frequently employed to evaluate the frontal sinus and its drainage pathway, enabling clinicians to identify abnormalities such as tumors, polyps, or foreign bodies. In this study, we investigated the anatomical intricacies of the frontal recess using specimens, CT scans, and endoscopic imagery sourced from didactic and clinical settings.

Inflammatory Modifications in Paranasal Sinuses and Ostiomeatal Complex Anatomical Variations in Jet Aircraft Pilots: A Computed Tomography Study.

Introduction Jet aircraft pilots are exposed to huge pressure variation during flight, which affect physiological functions as systems, such as the respiratory system. Objectives The objective of the present investigation was to evaluate inflammatory changes of paranasal sinuses of jet aircraft pilots before and after a jet aircraft training program, using multislice computed tomography (CT), in comparison with a group of nonairborne individuals with the same age, sex, and physical health conditions. A second objective of the present study was to assess the association between the ostiomeatal complex obstruction and its anatomical variations. Methods The study group consisted of 15 jet aircraft pilots participating in the training program. The control group consisted of 41 nonairborne young adults. The 15 fighter pilots were evaluated before initiating the training program and after their final approval for the presence of inflammatory paranasal sinus disease. The ostiomeatal complex anatomical variations and obstructions were analyzed in pilots after the training program. Results Jet aircraft pilots presented higher incidence of mucosal thickening in maxillary sinus and anterior ethmoid cells than controls. Prominent ethmoidal bulla showed significant association with obstruction of the osteomeatal complex. Conclusions Jet aircraft pilots present increased inflammatory disease when compared with nonairborne individuals. The presence of a prominent ethmoidal bulla is associated with ostiomeatal complex obstruction.

Efektifitas Variasi Window Width Terhadap Informasi Anatomi CT Scan Sinus Paranasal Citra Jaringan Lunak Pada Kasus Sinusitis

Background: Selection window width (WW) and window level (WL) must be precise to produce an optimal overview of anatomical information on CT scan paranasal sinuses soft tissue window in case of sinusitis. WW affects controlling contrast resolution. A wide window width will appear the less contrast of image. The aim of the study is to know the difference in anatomical information with variation WW and to know the most optimal WW value for CT scan paranasal sinuses soft tissue window in case of sinusitis.Methods: The research design is a quantitative experimental study, using WW variations (90, 120, 200, 350, 400). Anatomical assessment of osteomeatal unit, agger nasi cell, ethmoid roof, onodi cells, sphenoid sinus, optic nerve, middle turbinate, uncinate process, haller cells, And ethmoidal bulla. The friedman test is used to know a significant difference and the highest value of mean rank to know the most optimal WW value.Results: There is difference in information on each anatomical object with a significance value of 0.05 and there is difference in the total information on anatomical object with a significance value of 0.000 0.05. WW 120 is most optimal to display osteomeatal unit, agger nasi cell, ethmoid roof, onodi cells, middle turbinate, uncinate process, and ethmoidal bulla. WW 90 is most optimal to display sinus sphenoidalis, optic nerve, and haller cells.Conclusions: WW 120 is most optimal to display total anatomical information on CT scan paranasal sinuses soft tissue window in case of sinusitis.

The Upper Attachment of the Uncinate Process and Anterior Ethmoidal Artery.

Variations in the upper attachment of the uncinate process (UP) are important because they can affect frontal sinus drainage and change the morphology. Functional endoscopic sinus surgery (FESS) is the primary technique used to treat chronic medically refractory rhinosinusitis. Uncinectomy is the basis of FESS technique to obtain the best possible result from surgery. The anterior ethmoidal artery (AEA) enters the nasal cavity through the orbital medial wall (lamina papyracea) may also be affected by the upper attachment of the UP. The aim of this study was to investigate a possible link between UP variations and the course of the AEA. This retrospective, computed tomography (CT)-based, anatomic study was conducted on 200 healthy adults (100 females and 100 males) by screening bilateral paranasal sinus images. The upper attachment of the UP was classified in 6 types (1-6) based on the Liu classification. The AEA was divided into 4 types (A-D) based on location: anterior to the frontal sinus (A), between the frontal sinus and the middle nasal turbinate (B), and anterior to the posterior ethmoidal cells (C and D). All the CT images were evaluated simultaneously by 2 anatomists and 1 radiologist. Of the total cases (200 right and 200 left side), 48.8% were type 1 UP attachment, 11.0% type 2, 12% type 3, 9% type 4, 18% type 5, and 1.2% type 6. The AEAs were classified as 12.2% type A, 71.8% type B, 15.2% type C, and 0.8% type D. The course of the AEA through the nasal cavity was observed to shift anteriorly from the ethmoidal bulla to the frontal sinus in patients with UP attached to the lamina papyracea and middle turbinate. Remarkably, the AEA always coursed anterior from the middle nasal turbinate line.

The correlation between nasal and paranasal sinus anatomical variations with severity of Chronic Rhino Sinusitis Based on CT Scan Examination at Dr. Zainoel Abidin Hospital Banda Aceh

Background: Chronic rhinosinusitis (CRS) is a persistent inflammation of the nasal mucosa and paranasal sinuses. Anatomical variations of the nasal and paranasal sinuses can obstruct and impair the drainage and ventilation functions of the sinus ostium, causing CRS. Objective: To determine the correlation between nasal and paranasal sinus anatomical variations with the degree of severity of CRS based on a CT scan at Dr. Zainoel Abidin Hospital. Methods: An analytic observational study with a cross-sectional design from the results of CT scans of CRS patients in the period on October 2019-october 2022. The anatomical variations assessed were the degree of deviation of the nasal septum, type of bullous turbinate, paradoxical turbinate, hypertrophy of ethmoid bullae, Haller cells, deflection of uncinate process, type of superior insertion of the uncinate process, pneumatization of the uncinate process and frontal sinus cells to the degree of CRS using the Lund Mackay score. Data were analyzed using the Chi-Square test or Fisher's exact test. Result: Analysis of 64 CT scans consisting of 128 sides of the nose found a significant relationship between anatomic variations and the degree of CRS, namely the degree of deviation of nasal septum, type of concha bullosa, ethmoid bulla hypertrophy and deflection of the uncinate process to the severity of maxillary sinusitis (p=0.023; p=0.024; p=0.039; p=0.029) and paradoxical medial concha for the severity of maxillary sinusitis, anterior and frontal ethmoiditis (p=0.018; p=0.013; p=0.000) Conclusion: Anatomical variations of the nasal and paranasal sinuses are related to the severity of CRS.

Usefulness of the Three-step Simple Binostril Approach in Endoscopic Endonasal Transsphenoidal Surgery.

We describe a three-step, simple binostril approach to endoscopic endonasal transsphenoidal surgery in cases of sellar/parasellar lesions. In the first step, the mucosa of the lower third of the ethmoid bulla on the outside was coagulated with monopolar microdissection needle and opened to create space on the outside of the middle turbinate. The middle turbinate was moved outward using this space, and the natural ostium of the sphenoid sinus could be confirmed easily. In the second step, a less than 10 mm incision was made from the right natural ostium of the sphenoid sinus to the right nasal septal mucosa. The anterior wall of the sphenoid sinus was removed to free the sphenoid sinus. In the third step, the instrument was inserted through the left nostril using a hole connected to the natural ostium of the sphenoid sinus to reach the sellar floor via both nostrils. It took longer for the trainee than for the instructor to reach the sellar floor in the first four cases. However, there was no significant difference in the approach time after the fifth case. Approach-related postoperative complications were observed in 52 cases of sellar/parasellar lesions performed. This approach was considered to provide sufficient space and was simple and less burdensome to the patient.

Rare localization of the fungus ball

Fungus balls of the paranasal sinuses are one of the forms of non-invasive mycosis. Typical location of fungus balls of the paranasal sinuses is maxillary, sphenoid, ethmoid, and frontal sinuses. The article describes a case of a rare localization of the fungus ball in the ethmoid bulla.

CT Scans Imaging of Human Ethmoid Sinuses and Gross Anatomical Dissection: a Descriptive, Projective, Comparative, and Dimensional Study

Introduction: The ethmoid air sinus can subdivide into several air cells, which are separated from each other by thin, incomplete bony septa resulting in the formation of three groups of air cells (anterior, middle, and posterior cells). Methods: A randomized sample of 360 human individuals, including 110 cadavers with another 250 CT scan cases, was achieved from February 2020 to November 2021. Results: The agger nasi was the most common type of cell demonstrated by 81.8% in cadaveric cases and 94% in CT cases. The frontal bulla cell presents just above the ethmoidal bulla and may produce convexity on the frontal sinus floor. Its prevalence was 10.9% in cadaveric cases and 22.8% in CT cases. The suprabullar cell is on top of bulla ethmoidalis and represents 7.3% of cadaveric cases and 14.8% of CT cases. Concha bullosa presents as a comprehensive pneumatization in the middle turbinate. Its prevalence was 34.5% in cadaveric cases and 44% in CT cases. The Haller cell reveals as a pneumatized air-filled cell shown at the lower medial side of the orbit. It was in 29% of cadaveric cases and 42% of CT cases. In addition, the sphenoethmoid (Onodi) cell is a posterior ethmoidal cell with a prevalence of 41.8% in cadaveric and 64% in CT cases. Conclusion: This study described the morphologic anatomy of each ethmoid sinus and compared its dimensions by gross anatomy with CT scanning in different age groups. This yields clues to understanding the variations in human races and ethnic groups

Rhinogenic Contact Point Headache – a Review

Headache is a universal symptom in the course of everyone's life. There are myriads of causes for headache ranging from simple migraine, tension headache, refractory errors in the eye, temporomandibular joint arthralgia, and myofascial spasm to severe form of headache by brain tumors. The anatomical variations in the nasal cavity result in mucosal contact between the opposing surface and cause rhinogenic contact point headache (RCPH). RCPH is a new type of headache in medical literature. The pathogenesis of the RCPH is still the subject of controversy. Nose has diverse anatomical variations. Deviated nasal septum or spur, middle turbinate concha bullosa, and enlarged bulla ethmoidalis are the common anatomical variation in the nasal cavity which can cause RCPH. Diagnostic nasal endoscopy and computed tomography scan are helpful to confirm the mucosal contact points inside the nasal cavity. The precise excision of the contact points with the help of endoscopic approach in patients of RCPH is very effective. Clinicians should not ignore the anatomical variation of the nasal cavity during management of the headache. There is not much literature for RCPH indicating that this clinical entity is neglected. This review article presents an overview of the current aspect of RCPH.

Evaluation of paranasal anatomical variations with multidetector CT in Turkish population.

Abstract.

Trans-superior meatal surgery: A targeted approach for isolated posterior ethmoid diseases

BackgroundSurgical treatment for posterior ethmoid diseases has historically been performed through a trans-ethmoid approach which usually required medialization of the middle turbinate, a middle meatal antrostomy and total ethmoidectomy. This can destabilize the basal lamella of the middle turbinate and also sacrifices the integrity of ostiomeatal complex and the healthy bulla if the patient has the disease only in the posterior ethmoid sinus.The aim of this study is to present of a novel minimally disruptive approach for the management of isolated posterior ethmoid diseases. MethodsRetrospective case series analysis. Results19 patients with isolated posterior ethmoid fungal balls were operated on via a trans-superior meatal approach. The most common signs and symptoms were headache (78.9%), and purulent/mucoid discharge from the superior meatus (89.5%). The technique is described in detail with the preservation of the ostiomeatal complex and bulla ethmoidalis. Complete removal of the disease was achieved in all cases through this access, with no intra-operative complications. The posterior ethmoid cavity remained patent postoperatively in all patients. No recurrence was noted during the follow-up period which ranged from 6 to 12 months. ConclusionThis is a minimally invasive approach, which is safe and effective for the surgical management of isolated posterior ethmoid diseases.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Endoscopic Endonasal Approach to the Orbit.

Introduction Although endonasal endoscopic approaches (EEA) to the orbit have been previously reported, a didactic resource for educating neurosurgery and otolaryngology trainees regarding the pertinent anatomy, techniques, and decision-making pearls is lacking. Methods Six sides of three formalin-fixed, color latex-injected cadaveric specimens were dissected using 4-mm 0- and 30-degree rigid endoscopes, as well as standard endoscopic equipment, and a high-speed surgical drill. The anatomical dissection was documented in stepwise three-dimensional (3D) endoscopic images. Following dissection, representative case applications were reviewed. Results EEA to the orbit provides excellent access to the medial and inferior orbital regions. Key steps include positioning and preoperative considerations, middle turbinate medialization, uncinate process and ethmoid bulla removal, complete ethmoidectomy, sphenoidotomy, maxillary antrostomy, lamina papyracea resection, orbital apex and optic canal decompression, orbital floor resection, periorbita opening, dissection of the extraconal fat, and final exposure of the orbit contents via the medial-inferior recti corridor. Conclusion EEA to the orbit is challenging, in particular for trainees unfamiliar with nasal and paranasal sinus anatomy. Operatively oriented neuroanatomy dissections are crucial didactic resources in preparation for practical endonasal applications in the operating room (OR). This approach provides optimal exposure to the inferior and medial orbit to treat a wide variety of pathologies. We describe a comprehensive step-by-step curriculum directed to any audience willing to master this endoscopic skull base approach.

A Comparative Study of CT Scan and Nasal Endoscopic Findings of Lateral Wall of Nose, in Headache of Rhinogenic Origin.

Headache disorders are rated among the ten most disabling conditions worldwide. Contact points like septal spur, septal deviation, concha bullosa and bulla ethmoidalis can cause rhinogenic headache (RH). Diagnostic nasal endoscopy (DNE) is an essential part of evaluation of sinonasal disease and is the key to understanding anatomical variations. As compared to CT paranasal sinus (CT PNS), DNE is cheaper and has wider availability, being part of the basic training of present ENT curriculum. We conducted a prospective observational study from September 2018 to June 2020 on 202 patients who were diagnosed to have RH. The aim of this study was to the define the role of DNE as the primary examination for early and accurate diagnosis of rhinogenic headache as compared to CT PNS. RH patients were evaluated with DNE followed by CT PNS. Evaluation of the findings of anatomical variations of lateral wall of nose on DNE and CT PNS was done. In our study the most common anatomic variations in order of frequency in both DNE and CT PNS was deviated nasal septum, impacting spur and unilateral concha bullosa. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of DNE for the various anatomical variations was statistically better than CT PNS findings. We conclude that DNE is a better than CT PNS as a diagnostic technique to detect various anatomical variations, thus initiating early management of RH.

The effect of paranasal anatomic variations on chronic rhinosinusitis

Rhinosinusitis is the inflammation of the paranasal sinus mucosa and the most common pathophysiological event causing rhinosinusitis is the ostiomeatal complex disease. The aim of the study is to determine the prevalence of anatomical variations and mucosal pathologies in paranasal computed tomography images of patients with chronic rhinosinusitis and to reveal the relationship between anatomical variations and sinus pathologies. Anatomical variations and mucosal pathologies in coronal paranasal tomography images were evaluated in 100 patients diagnosed with chronic rhinosinusitis and 32 individuals in the control group without any sinus complaints. The rate of having at least one anatomical variation in the control group was 64.1%, while this rate was 87.5% in patients with chronic rhinosinusitis (p<0.001). The most common variation, Agger nasi cell, was found to be present in 34.3% of the individuals in the control group and in 53.5% in the rhinosinusitis group (p<0.05). In patients with rhinosinusitis, maxillary sinus was affected in 66.5%, anterior ethmoid sinus in 42.5%, frontal sinus in 32.5%, posterior ethmoid sinus in 20%, sphenoid sinus in 18.5% either in isolation or in combination. The relationship between anatomical variations and mucosal pathologies of the sinuses was evaluated. A significant correlation was found between anatomical variations such as Agger nasi cell, concha bullosa, septum deviation, ethmoid bulla and Haller cell with maxillary sinusitis, between Agger nasi cell and septum deviation with frontal sinusitis, and between Agger nasi cell, concha bullosa, septum deviation and ethmoid bulla with ethmoid sinusitis. In conclusion; it was concluded that anatomical variations are an important factor in the development of chronic sinusitis and that not only sinuses but also anatomical variations that impair drainage should be corrected during the surgical treatment of rhinosinusitis.

Anterior Skull Base Analysis from Coronal and Reconstructed Computed Tomography: Radio-Anatomical Study

Endoscopic sinus and skull base Surgery has gained significant improvement widely all over the world. A computerized tomography (CT) scan provides a detailed anatomy of the skull base especially the bone framework. This study aims to analyze the fixed anatomical bony landmarks of the anterior skull base through coronal and reconstructed CT in the context of the Nepalese population and guide the surgeon to perform endoscopic sinus and skull base surgery safely. This Prospective study includes 70 Computerized Tomography scans of Paranasal sinuses. The different measurement from nasal floor to skull base was taken in coronal and reformatted sagittal CT scan. Mean, standard deviation, minimum and maximum values were analyzed using descriptive statistics. Student T-test was applied to compare between right and left side. This study includes 75 patients between 18 to 77 years. The measurement from nasal floor to the cribriform plate and ethmoidal roof in right and left side were, mean± SD (47± 4.1, 45.3±4.3, 47.9±5.1, and 49±8.5 mm) respectively. Mean Take off angle at the cribriform plate was 43.9 ±10.9°on right side and 43 ± 9.4° on the left side. The distance from the nasal spine to the skull base (mean ± SD) at nasofrontal recess, bulla ethmoidalis, and the junction of sphenoethmoid levels at right sides were 51.5 ± 4.7, 52.9 ± 4.1, and 61.2 ±4.7 little higher at left side. This study provides a detailed analysis of the anterior skull base in coronal and sagittal CT scans which helps to reduces complications.

Computed tomography analysis of the anterior ethmoid genu of the frontal recess in non-diseased sinuses.

Knowledge of anatomical variations of the frontal recess and frontal sinus and recognition of endoscopic landmarks are vital for safe and effective endoscopic sinus surgery. This study revisited an anatomical landmark in the frontal recess that could serve as a guide to the frontal sinus. Prevalence of the anterior ethmoid genu, its morphology and its relationship with the frontal sinus drainage pathway was assessed. Computed tomography scans with multiplanar reconstruction were used to study non-diseased sinonasal complexes. The anterior ethmoidal genu was present in all 102 anatomical sides studied, independent of age, gender and race. Its position was within the frontal sinus drainage pathway, and the drainage pathway was medial to it in 98 of 102 cases. The anterior ethmoidal genu sometimes extended laterally and formed a recess bounded by the lamina papyracea laterally, by the uncinate process anteriorly and by the bulla ethmoidalis posteriorly. Distance of the anterior ethmoidal genu to frontal ostia can be determined by the height of the posterior wall of the agger nasi cell rather than its volume or other dimensions. This study confirmed that the anterior ethmoidal genu is a constant anatomical structure positioned within frontal sinus drainage pathway. The description of anterior ethmoidal genu found in this study explained the anatomical connection between the agger nasi cell, uncinate process and bulla ethmoidalis and its structural organisation.