Are the Ethmoidal Foramina Through the Frontal Bone, Ethmoid Bone, or Frontoethmoidal Suture?

INTRODUCTION: To investigate the locations of the anterior, middle, and posterior ethmoidal foramina and their relationships to the frontoethmoidal suture. METHODS: One hundred twenty sides from sixty adult human skulls were used. Specimens with significant damage to the medial orbit wall were excluded. The number of ethmoidal foramina (anterior, middle, and posterior) on the medial orbital wall and the relationship of each foramen to the frontoethmoidal suture were recorded and classified as follows: Type I: superior to the frontoethmoidal suture; Type II: on the frontoethmoidal suture; Type III: inferior to the frontoethmoidal suture. RESULTS: Of the ninety-four sides, fourteen (14.9%) had one foramen, sixty-two (66.0%) had two , and eighteen (19.1%) had three. In total, 192 ethmoidal foramina were observed. Among the fourteen sides with one foramen, eight foramina were anterior and six were posterior. Among the 192 ethmoidal foramina, 162 were eligible for fur ther classification (74 anterior, 14 middle, and 74 posterior). Types I, II, and III ethmoidal foramina were found in 38.3% (62/162), 61.7% (100/162), and 0% (0/162), respectively. CONCLUSIONS: Our current study found a higher incidence of type I than previously reported. It is important to be aware of the significant incidence of foramen variations when the medial orbit wall is manipulated during surgery. Unless caution is observed, an inadvertent surgical injury can occur and lead to life-threatening complications. Therefore, a good understanding of orbital anatomy and its potential variations is critical for improving patient out comes.

Examination of ethmoidal roof regarding Keros and Yenigun classifications in a Turkish population: a computerized tomography study.

PURPOSE: Understanding ethmoid roof morphology is crucial to prevent complications in endoscopic sinus surgery. This study aimed to evaluate the morphological properties of the ethmoidal roof regarding gender and age differences using Keros and Yenigun classifications on high-resolution computed tomography images. METHODS: We retrospectively analyzed 891 high-resolution computed tomography paranasal sinus study images and measured the depth of the cribriform plate in coronal sections and the anterior-posterior length in axial planes. The study retrospectively examined CT images of paranasal sinuses of patients living in the eastern Anatolian region of Turkey. RESULTS: In both Keros and Yenigun Classifications, the most common class was type 2, and the least common class was type 3. According to Keros et al.'s method, no significant difference was observed between men and women (p = 0.698). However, according to Yenigun et al., the average values of women in terms of the anterior-posterior distance of the ethmoid roof were significantly higher than men (p = 0.001). When examined according to age, a very low, negative correlation was revealed regarding Keros and Yenigun classifications (p = 0.047 and p < 0.001 retrospectively). According to Keros and Yenigun's classification, there was no significant difference between the left and right sides (p = 0.488 and p = 0.919, respectively). CONCLUSION: The morphological properties of the ethmoidal roof have importance to be considered for preoperative planning. Studying larger patient groups and meta-analyses that gather various research results about this subject might help better understand the ethmoidal roof morphology among populations.

Review of olfactory cleft roof anatomy.

Progress in skull-base endoscopic surgery has improved our knowledge of olfactory cleft (OC) anatomy. This article presents a review of current knowledge concerning the OC roof: descriptive anatomy, radiological exploration, and endoscopic observation. The OC is a narrow area in the most superior part of the nasal cavity. Its roof is the thinnest structure separating the nasal cavities from the brain; it comprises three superimposed tissues: nasal mucosa, ethmoid cribriform plate (ECP), and dura mater. The ECP comprises the anterior ECP containing the ethmoidal slit (ES) medially and the cribroethmoidal foramen (CEF) laterally; and the posterior ECP, comprising the olfactory foramina. The OC roof is bordered anteriorly by the nasal bone roof, laterally by the lateral ethmoid masses, and posteriorly by the jugum and anterior wall of the sphenoid sinuses. Imaging is crucial for analyzing this wall, providing precise detailed information on conformation and anatomic relations with adjacent structures such as the anterior ethmoidal artery. Understanding OC roof anatomy and correct interpretation of imaging are essential for safety in present-day functional endoscopic sinus surgery and anterior skull-base oncologic surgery.

Crista Galli Morphometry and Morphology: An Anatomical, Radiological, and Machine Learning Application Study / Crista Galli Morfometría y Morfología: Un Estudio de Aplicación Anatómica, Radiológica y de Aprendizaje Automático

SUMMARY: The study purposed to examine the morphometry and morphology of crista galli in cone beam computed tomography (CBCT) and apply a new analysis, supervised Machine Learning techniques to find the answers to research questions "Can sex be determined with crista galli morphometric measurements?" or "How effective are the crista galli morphometric measurements in determining sex?". Crista galli dimensions including anteroposterior, superoinferior, and laterolateral were measured and carried out on 200 healthy adult subjects (98 females; 102 males) aged between 18-79 years. Also, crista galli was classified with two methods called morphological types and Keros classification. In this study, the Chi-square test, Student's t-test, and Oneway ANOVA were performed. Additionally, Machine Learning techniques were applied. The means of the CGH, CGW, and CGL were found as 14.96 mm; 3.96 mm, and 12.76 mm in males, respectively. The same values were as 13.54 mm; 3.51 mm and 11.59±1.61 mm in females, respectively. The CG morphometric measurements of males were higher than those of females. There was a significant difference between sexes in terms of morphological classification type. Also, when the sex assignment of JRip was analyzed, out of 102 male instances 62 of them were correctly predicted, and for 98 female instances, 70 of them were correctly predicted according to their CG measurements. The JRip found the following classification rule for the given dataset: "if CGH<=14.4 then sex is female, otherwise sex is male". The accuracy of this rule is not high, but it gives an idea about the relationship between CG measurements and sex. Although the issue that CG morphometric measurements can be used in sex determination is still controversial, it was concluded in the analysis that CG morphometric measurements can be used in sex determination. Also, Machine Learning Techniques give an idea about the relationship between CG measurements and sex.

En el estudio se propuso examinar la morfometría y la morfología de la crista galli del hueso etmoides usando tomografía computarizada de haz cónico (CBCT) y aplicar un nuevo análisis, técnicas de aprendizaje automático supervisado para encontrar las respuestas a las preguntas de investigación "¿Se puede determinar el sexo con mediciones morfométricas de la crista galli?" o "¿Qué tan efectivas son las medidas morfométricas de la crista galli para determinar el sexo?". Las dimensiones de la crista galli, incluidas los diámetros anteroposterior, superoinferior y laterolateral, se midieron y realizaron en 200 sujetos adultos sanos (98 mujeres; 102 hombres) con edades comprendidas entre los 18 y los 79 años. La crista galli se clasificó con dos métodos llamados tipos morfológicos y clasificación de Keros. En este estudio, se realizaron la prueba de Chicuadrado, la prueba t de Student y ANOVA de una vía. Adicionalmente, se aplicaron técnicas de Machine Learning. Las medias de CGH, CGW y CGL se encontraron en 14,96 mm; 3,96 mm y 12,76 mm en hombres, respectivamente. Los mismos valores fueron 13,54 mm; 3,51 mm y 11,59 ± 1,61 mm en mujeres, respectivamente. Las medidas morfométricas del CG de los hombress fueron más altas que las de las mujeres. Hubo una diferencia significativa entre sexos en cuanto al tipo de clasificación morfológica. Además, cuando se analizó la asignación de sexo de JRip, de 102 instancias masculinas, 62 de ellas se predijeron correctamente, y de 98 instancias femeninas, 70 de ellas se predijeron correctamente de acuerdo con las mediciones de CG. El JRip encontró la siguiente regla de clasificación para el conjunto de datos dado: "si CGH<=14.4, por tanto el sexo es femenino, de lo contrario, el sexo es masculino". La precisión de esta regla no es alta, pero da una idea de la relación entre las medidas del CG y el sexo. Aunque la pregunta si las medidas morfométricas CG se pueden usar en la determinación del sexo sigue aún siendo controvertida. Se concluyó en el análisis que las medidas morfométricas CG se pueden usar en la determinación del sexo. Además, las técnicas de aprendizaje automático dan una idea de la relación entre las medidas de CG y el sexo.

Anterior ethmoid and frontal sinus drainage pathways: five patterns formed and defined by their bony walls.

PURPOSE: To perform endoscopic sinus surgery safely and effectively, surgeons need to visualize the complex anatomy of the anterior ethmoid and frontal sinus region. Because this anatomy is so variable and individualized, the foundation of understanding lies in identifying, following, and visualizing the drainage pathway patterns and anticipating possible variations. METHODS: We studied 100 sides (50 cases: 22 male, 28 female, aged 12-86, average age 46.5 years, ± 19.5) using computed tomography (CT) and multiplanar reconstruction (MPR) to identify and classify the drainage pathways leading to the frontal sinus and anterior ethmoidal cells. RESULTS: Analysis revealed five patterns of drainage pathways defined by their bony walls: between the uncinate process and the lamina papyracea [UP-LP]; between the uncinate process and the middle turbinate [UP-MT]; between the uncinate process and the accessory uncinate process [UP-UPa]; between the uncinate process and the basal lamella of the ethmoidal bulla [UP-BLEB]; and between the basal lamella of the ethmoidal bulla and the basal lamella of the middle turbinate [BLEB-BLMT]. In most cases, BLEB formed the posterior wall of the drainage pathway of the frontal sinus, indicating BLEB could be one of the most important landmarks for approaching the frontal sinus. CONCLUSIONS: As endoscopic sinus surgery depends on an understanding of this anatomy, this study may help surgeons to identify and follow the drainage pathways more accurately and safely through the anterior ethmoid to the frontal sinus.

Nasosinusal Endoscopic Anatomy and Physiology

The present article focuses on the analysis of the nasal cavity's anatomy succinctly and descriptively. This essay was carried out through a bibliographic review, directed to the detailed anatomy of the nasal cavity, and the structures that form its sinuses. We have identified the need formore studies directed to the related anatomical area so that the improved knowledge of this region ensures a nasoendoscopic treatment with better effectiveness and no complications.

Anatomical Study of Ethmoidal Foramina and Optic Canal in Endoscopic Trans-Nasal Approach to Anterior Skull Base.

BACKGROUND: Surgery to anterior skull base is challenging since complex structures are involved. Injury of olfactory fila and optic nerve may result in postoperative complications. In our study, the authors aim to use computer topographic image to provide a comprehensive anatomical information of anterior skull base and set up a new classification of optic canal (OC) in ethmoid sinus by the degree of bony defect, so as to help surgeons in endoscopic transnasal approach to anterior skull base. METHOD: Computer topographic angiography images of 112 individuals were reviewed, the measurement was performed on coronal, sagittal, and axis planes after the multiplanar reformation. Nostril and mid-sagittal lines were used to locate the anterior, middle, and posterior part of ethmoidal foramina and orbital opening of OC. Further, the authors classified OC in ethmoidal sinus into 4 types by the degree of the bony defect. RESULT: Distance between nostril to anterior, middle, and posterior part of ethmoidal foramina and OC are 6.23 ± 0.21, 6.62 ±â€Š0.26, 7.29 ±â€Š0.25, and 7.76 ±â€Š0.41 mm, respectively. Angle between line from nostril to ethmoidal foramina and horizontal plane are 47.50°â€Š±â€Š1.03°, 41.67°â€Š±â€Š1.33°, 37.20°â€Š±â€Š1.34°, respectively. For the 4 types of OC, the percentage is 15.6%, 11.6%, 31.3%, and 41.5%, respectively. CONCLUSIONS: Our findings provide anatomical information of ethmoidal foramina and OC during endoscopic transnasal approach to anterior skull base, on the basis of some fixed anatomical landmarks. So as to enhance the surgical safety of this procedure and aid in the choice of the appropriate endoscopic equipment for the procedure.

[Proposal for the delineation of postoperative primary clinical target volumes in ethmoid cancers]. / Proposition de délinéation des volumes cibles anatomocliniques postopératoires de la tumeur primitive des cancers de l'ethmoïde.

It is proposed to delineate the anatomo-clinical target volumes of primary tumor (CTV-P) in ethmoid cancers treated with post-operative radiotherapy. This concept is based on the use of radioanatomy and the natural history of cancer. It is supported by the repositioning of the planning scanner with preoperative imaging for the replacement of the initial GTV and the creation of margins around it extended to the microscopic risk zones according to the anatomical concept. This article does not discuss the indications of external radiotherapy but specifies the volumes to be delineated if radiotherapy is considered.

Anatomical Factors that Can Predict the Structure of Lamina Papyracea for Endoscopic Sinus Surgery.

OBJECTIVES: This study investigated morphological variations of lamina papyracea, the structure that should be carefully considered when opening posterior ethmoid sinus during endoscopic sinus surgery, to avoid injury. STUDY DESIGN: This study employed axial, coronal, and sagittal computed tomography. METHODS: Using computed tomography images of 228 face-sides, various anatomical parameters were determined: distances of the anterior and posterior ethmoid arteries from the skull base, and from the third lamella; changes in the angles of the lamina papyracea at the anterior and posterior ethmoid sinuses; and presence or absence of supraorbital ethmoid cell (SECs), Onodi cell, and Haller cell. The relationship between the distances which indicate the point of maximum projection by the lamina papyracea among third lamina and posterior ethmoid artery into the posterior ethmoid sinus and these anatomical factors were analyzed statistically. RESULTS: The projection distance of lamina papyracea into the posterior ethmoid sinus was -2.6 mm to 3.4 mm, and in 41.2% of cases, projection in the direction of the nasal cavity was greater than that of the lamina papyracea at the anterior ethmoid sinus. This distance increased with increasing distance of the maximum projection point from the skull base and increasing floating distances of the anterior and posterior ethmoid arteries. The number of subjects with large projection distances was increased among those with floating posterior ethmoid arteries. In addition, subjects with SECs had significantly greater projection distances. CONCLUSIONS: Particular care should be taken to avoid injury to the lamina papyracea when opening the posterior ethmoid sinus in subjects with floating anterior or posterior ethmoid arteries, and/or SEC. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E19-E25, 2021.

Domesticating olfaction: Dog breeds, including scent hounds, have reduced cribriform plate morphology relative to wolves.

The domestic dog is assumed by nearly everyone to be the consummate smeller. Within the species Canis familiaris individual breeds, such as the bloodhound or beagle, are known as olfactory stars. These are "scent breeds," a grouping variably defined as a genetic clade or breed class commonly used for scent detection tasks. Previous work suggests that the dog has a more robust olfactory anatomy than many mammal species. Now we undertake a closer investigation of the dog's olfactory system, both in relationship to its closest wild relatives, the wolf and coyote, and across individual breeds. First, we seek to resolve whether the dog has lost olfactory capacity through its domestication from the wolf lineage. Second, we test the inertial lore that among dogs, "scent breeds," have a superior olfactory facility. As a measure of relative olfactory capacity, we look to the cribriform plate (CP), a bony cup in the posterior nasal cavity perforated by passageways for all olfactory nerve bundles streaming from the periphery to the brain. Using high-resolution computed tomography (CT) scans and digital quantification, we compare relative CP size in 46 dog breeds, the coyote and gray wolf. Results show the dog has a reduced CP surface area relative to the wolf and coyote. Moreover, we found no significant differences between CP size of "scent" and "non-scent" breeds. Our study suggests that the dog lost olfactory capacity as a result of domestication and this loss was not recovered in particular breed groupings through directed artificial selection for increased olfactory facility.

Classification of crista galli pneumatization and clinical considerations for anterior skull base surgery.

Cerebrospinal fluid (CSF) leakage caused by frontal sinus exposure is a serious complication in the basal interhemispheric approach (BIHA). Crista galli pneumatization (CGP) is often observed on preoperative computed tomography (CT) scan. The aim of this study was to classify and describe variations in anatomical measurements of CGP. We examined CT images of 300 patients with brain tumors to assess the morphology and incidence of CGP. Crista galli were classified according to their location relative to the cribriform plate and the presence of pneumatization. The paranasal sinuses were investigated as the origin of CGP. We assessed 24 patients using the BIHA for skull base tumors; these patients were included as clinical cases to assess the range of skeletonization of the crista galli and determine the route of CSF leakage in the other 276 patients. CGP was found in 28/300 CT scans, including upper, middle, and lower type CGPs. The origin of CGPs was the frontal sinus or ethmoid sinus. All CGPs were localized in the anterior half of the crista galli. In the 24 consecutive clinical cases, there were 13 tuberculum sellae meningiomas, 3 craniopharyngiomas, and 8 with other pathologies. The preoperative crista galli height was 12.3 mm and the distance from the top of the skeletonization to the cribriform plate was 5.2 mm. CGP originating from the paranasal sinuses can lead to CSF leakage. In cases where CGP originates from the ethmoid sinus, care should be taken to seal the exposed crista galli intradurally.

Impact of the ethmoid volume on endoscopic medial wall decompression outcomes in Graves' orbitopathy.

BACKGROUND: Endoscopic orbital decompression is a well-established technique for Graves orbitopathy treatment. AIMS: Measurement of the ethmoid volume and its correlation with proptosis reduction in patients undergoing endoscopic orbital decompression for Graves' orbitopathy. METHODS: We retrospectively reviewed clinical charts of 209 patients (319 orbits) operated by a surgeon at our institution between 1998 and 2019. RESULTS: Average age was 46.9 years. About 83.3% of the patients were female, 54.6% were smokers, 93.8% were euthyroid at the time of decompression, 3.8% were hypothyroid and 2.4% were hyperthyroid. About 77.5% of the patients underwent bilateral surgery, the remainder and unilateral. Subsequent stages included strabismus surgery in 22.5% patients, Müllerectomy 37.8%, with or without canthoplasty (14.8 vs. 23%). Mean proptosis reduction was 4.61 mm. Mean ethmoid volume was 5.57 mm3. Ethmoid volume had a moderate positive correlation with proptosis reduction (r s = 0.49, p < .001). Further investigation, statistically significant moderate correlation was found only in the small (SE) and big (BE) ethmoid groups. CONCLUSION: We advise evaluating ethmoid sinus pneumatization on computed tomography before decompression to estimate possible anatomical limitations. Additional wall decompression might be advocated in most severe cases.

Incidence of anatomical variations according to the International Frontal Sinus Anatomy Classification (IFAC) and their coincidence with radiological sings of opacification.

BACKGROUND: The endonasal access to the frontal recess and sinus may be complicated by a variety of anatomical variations. Previous classifications of these variants were characterized by proper names or position information without anatomical reference. The IFAC is intended to simplify the classification of anatomical variations of the frontoethmoidal complex. The aim of this study was to analyse a representative number of sinus CT scans to assess the incidence of anatomical variations according to the IFAC and to compare the results with previous classifications. In addition, the coincidence of complex anatomical variations and radiological sings of opacification was investigated. METHODOLOGY/PRINCIPAL: Two hundred and forty-nine sinus CT scans were analysed in multiplanar reconstructions. Exclusion criteria were previous operations on the paranasal sinuses, malignant diseases, and an insufficient image quality. All anatomical variants were analysed according to the IFAC criteria. In addition, the coincidence of radiological sings of opacification and the presence of anatomical variations of the frontal recess and sinus were investigated. RESULTS: The analysis revealed Agger nasi cells in 95% of the CT scans. Supra agger cells (SACs) were detected in 49% and Supra agger frontal cells (SAFCs) in 25% of the data sets. Suprabulla cells (SBCs) were detected in 89% and Supra bulla frontal cells (SBFCs) in 27% of the scans. Supraorbital ethmoid cells (SECs) were detectable in 9% and interfrontal septal cells in 28% of the scans. Despite a partially strong narrowing of the frontal recess, no increased occurrence of radiological sings of opacification could be detected (p > 0.05). CONCLUSIONS: Anatomical variations in the frontoethmoidal area are very common. According to the IFAC criteria, in 43% of the patients, cells could be detected with pneumatization to or into the frontal sinus. The IFAC is structured more clearly compared to previous classifications due to the anatomical aspect. It represents the most consistent classification regarding surgical planning. Further studies will demonstrate the scientific and clinical value of this classification.

Anatomic variations associated with antrochoanal polyps.

OBJECTIVE: Although more than a century has passed since antrochoanal polyps (ACPs) were first defined, etiopathogenesis still remains unclear. The aim of this study was to investigate the relationship between ACPs and sinonasal cavity variations. SUBJECTS AND METHODS: One hundred and forty-four patients with ACP on paranasal sinus computed tomography scans (ACP group) and 160 paranasal sinuses without ACP (control group) were included into the study. The study group was evaluated in respect of the presence of retention cyst in the contralateral maxillary sinus and sinus bone wall sclerosis thickening. Both groups were also compared with respect to the frequency of sinonasal anatomic variations, nasal septal deviation, variations of the uncinate process insertion, concha bullosa, paradoxical middle turbinate, and accessory maxillary sinus ostium. In the ACP group, the cases with septal deviation (SD) were also evaluated whether the deviation convexity was towards the polyp side or the opposite side. In addition, the posterior extension of ACPs were evaluated in three groups as middle meatus, nasopharynx, and oropharynx extension. RESULTS: The prevalence of retention cyst, sinus wall sclerosis thickening, SD, and accessory maxillary ostium was significantly higher in the ACP group. A negative directional correlation was determined between the SD side and ACP side. When the ACP extensions were examined, middle meatus extension was seen in 32.6%, nasopharynx in 56.3%, and oropharynx in 11.1%. CONCLUSION: Accessory ostium may be an accelerating factor in the transformation of retention cyst to ACP. Furthermore, the changes in the nasal passage airflow on the opposite side suggest that SD contributes to this process.

Anatomical Characteristics of the Perpendicular Plate of the Ethmoid: An Analysis of Paranasal Sinus Computed Tomography via Three-Dimensional Reconstruction.

In recent years, the perpendicular plate of the ethmoid (PPE) has emerged as a new autogenous grafting material in rhinoplasty and septoplasty of nasal deviation. However, no studies have outlined the precise size, shape, and morphologic features of the PPE. Therefore, this study aimed to provide detailed information on the anatomical and morphologic characteristics of the PPE to assist surgeons in performing surgeries that are more precise. About 104 Chinese patients who underwent paranasal computed tomography were assessed in this study. By analyzing the features of the PPE reconstructed with 3-dimensional models, the characteristics of the PPE at different stages of development and according to sex were observed. The PPE had a flat shape, and its lower part was relatively thin. It usually developed horizontally with age, which contributed to expansion of the PPE area. The dimensions of the PPE were significantly larger in male patients than in female patients. Through the reconstruction and measurement of Chinese patients' PPE, the authors have established precise information about the PPE's anatomical and morphologic features. The flat shape and proper size, which are similar to those of nasal septum cartilage, make the PPE an ideal alternative to conventional autogenous grafting materials. The findings might be useful to surgeons in helping them perform surgeries that are more precise.

The lamina push test: an alternative to the globe push test for identifying the medial orbit during endoscopic sinus surgery.

BACKGROUND: Aside from endoscopic and image guidance confirmation, the standard method of identifying the lamina involves the surgeon or an assistant applying gentle pressure on the globe externally. This globe push test requires the surgeon to remove one instrument from the endoscopic field or an assistant to press on the globe, and the test is most useful when either the periorbita or periorbital fat is exposed. We propose an alternative, equally accurate, and more efficient technique dubbed the lamina push test. METHODS: A blunt instrument is used to gently apply lateral pressure in the expected location of the medial orbital wall. If the lamina has been adequately skeletonized, the entire lamina will be seen to move as a unit. If residual ethmoid partitions are present, no movement or only localized movement is observed. RESULTS: Using the lamina push test, we have been able to safely identify the lamina papyracea in all patients undergoing endoscopic sinus surgery, without injury to the lamina or orbital contents. The use of direct pressure significantly increases the movement of an intact lamina. CONCLUSION: The lamina push test is a safe and effective technique for identification of the medial orbital wall, confirmation of removal of all lateral ethmoid partitions, and verification of lamina integrity. It enables more consistent identification of an intact lamina, allows the surgeon to keep both instruments in the endonasal surgical field, and does not require an assistant.

Cribriform plate width is highly variable within and between subjects.

OBJECTIVE: All successful endonasal surgery, including functional endoscopic sinus surgery (FESS), depends on knowledge of both anatomy and the specific variations that can occur between and within patients. Familiarity with these structures is a critical component in preventing complications from these procedures, and failure to understand subtle variation can have disastrous results. The aim of this study was to characterize the anatomical variations (if any) of the cribriform plate using a large cadaveric sample set. Better understanding of the disparities within and between patients may have important implications for surgical planning. METHODS: Whole human skull specimens (31 specimens, 62 sides) were examined to obtain dimensional measurements of the cribriform plate on the right and left sides. RESULTS: The average length of the cribriform plate was 21.28mm (range 15.25-27.73mm, SD 3.30mm). The average width of the cribriform plate (including the crista galli) was 4.53mm (range 1.75-8.03mm, SD 1.20mm). When comparing side differences in individual specimens, there was more variability between widths, relative standard deviation 26.4%, than between lengths, relative standard deviation 15.5%. CONCLUSION: There is a range of both length and width of the cribriform plate, between and within individuals. This is particularly true for width. In practice, this emphasizes the importance of pre-operative imaging and recognition of anatomic variability for sinus or anterior skull base procedure.

The Terracol and Ardouin developmental model of frontal sinus drainage pathway and surrounding spaces: a radiologic validation.

BACKGROUND: The complexity of the frontal sinus drainage pathway (FSDP) can be challenging even for expert surgeons. Several classifications have been proposed to simplify the understanding of FSDP, whose anatomical variability can be simplified based on the knowledge of its developmental mechanisms. METHODS: Cone-beam computed tomography studies performed at the Unit of Radiology of the University of Brescia between March and November 2012 were retrospectively analyzed. FSDP was classified as medial or lateral to the vertical portion of the uncinate process and the following anatomical variants were studied: agger nasi cell, Kuhn's cells, suprabullar cell, supraorbital ethmoid cell, suprabullar frontal cell, and frontal septal cell. The developmental model of the FSDP proposed by Terracol and Ardouin was analyzed and expected associations between the position of the drainage pathway and anatomical variants were formulated. Statistical associations between anatomical variants and the position of FSDP were calculated and compared with expected associations to validate the developmental model. RESULTS: The anatomical variants of FSDP statistically validated the developmental model of Terracol and Ardouin. CONCLUSION: Knowledge of the possible developmental patterns of FSDP helps the surgeon in the understanding of the complexity of the frontoethmoidal region.

Osteologic analysis of ethnic differences in supernumerary ethmoidal foramina: implications for endoscopic sinus and orbit surgery.

BACKGROUND: Knowledge of the position of the ethmoidal arteries is critical to enable safe endoscopic sinus and orbital surgery. The presence of a third or "middle" ethmoid variant has recently become more relevant as endoscopic intraconal surgery continues to advance. The purpose of this study was to quantify the presence of supernumerary (ie, over 2) ethmoid foramina in different ethnicities and genders. METHODS: Morphometric osteologic measurements were performed in 273 orbits. Prevalence of supernumerary ethmoid foramina and orbital length data were obtained from human skulls of Asian (n = 54), Caucasian (n = 70), African (n = 39), Hispanic (n = 49), and Middle Eastern (n = 61) derivation. Correlations between gender, ethnicity, symmetry, orbital floor, and lamina papyracea length were assessed by analysis of variance, paired t test, and χ2 test. RESULTS: Supernumerary foramina were identified in 95 of 273 orbits (34.79%). A significantly higher prevalence was seen in Asian (42.59%), African (41.02%), and Hispanic (41.00%) skulls as compared with Caucasian (25.71%) and Middle Eastern (22.95%) skulls (p < 0.05 for all). The length of the orbital floor was significantly shorter in the Asian (3.35 ± 1.52 cm) specimens (p < 0.01). Asians were found to have the highest risk of ethmoid artery injury compared with the other ethnic groups (ratio of number of supernumerary foramina to orbital floor length = 0.72). CONCLUSION: Supernumerary ethmoidal foramina were common among all orbits studied. Orbits of Asian and African derivation had significantly greater numbers of ethmoidal foramina, both unilaterally and symmetrically and within a shorter orbital length, suggesting a greater proximity between the ethmoidal vessels. Surgeons should be alert to the possible presence of middle ethmoidal vessels during endoscopic sinus and orbital approaches.

An Applied Anatomical Study of the Ethmoidal Arteries: Computed Tomographic and Direct Measurements in Human Cadavers.

Computed tomography (CT) images have been used in very few studies on distances to the ethmoidal arteries in the orbit. Most other studies have included direct measurements on cadavers and frequently quote the 24-12-6 mm rule to describe distances from the anterior lacrimal crest to the anterior and posterior ethmoidal foramina (AEF and PEF), optic canal (OC), respectively. However, the large interindividual variation of distances renders absolute values less applicable in a clinical setting. Preoperative measurements on CT images may provide more precise distances than absolute rules and thus lead to safer orbital surgery. The authors hypothesize that the distances to the ethmoidal arteries and the length of the medial wall are positively correlated and that measurements of the distances from the posterior lacrimal crest (PLC) on CT images are feasible with a low intra- and interobserver variability.Fifty intact orbits from 25 Caucasian cadavers were exenterated and examined. In additional, high-resolution CT scans of 48 orbits from 24 other Caucasian nonexenterated cadavers were examined. Distances were measured from 4 different anterior landmarks to the AEF and PEF and the OC.Distances from the most anterior landmarks to the arteries were positively correlated with the length of the medial wall. Measurements of the distances from the PLC to the ethmoidal arteries on CT images were feasible with a low intra- and interobserver variability. In conclusion, iatrogenic damage to the ethmoidal arteries in the orbit may be best avoided by using CT measurements in presurgical planning.