Keros Type Research Articles

STUDY OF MORPHOLOGY OF THE ETHMOIDAL ROOF ON CT SCAN IN PATIENT WITH NASOSINUSAL SYNDROMES

Background: The ethmoidal roof is the thinnest bone of the skull base. Study of morphology of the ethmoidal roof on sinus CT Scan to avoid damaging the ethmoidal roof during sinus surgery. Objective: Describe the shape of the ethmoidal roof and some adjacent structures on computed tomography. Survey the relation between the shape of the ethmoidal roof and some adjacent structures. Patients and methods: Including 177 patients with nasosinusal syndromes who examined and underwent sinus CT scan at Hue University of Medicine and Pharmacy. Result: The mean hight of the lateral lamella of the cribrifom plate is 4.27 ± 1.96 mm on the right and 4.64 ± 1.92mm on the left. Keros type 1 accounted for 41.5%, type 2 accounted for 47.2% and type 3 accounted for 11.3%. Keros classification on the left was significantly higher than that on the right side. The hight of the nasal cavity was lowest in the Keros type 1 group and highest in type 3 (p=0.001). For more than 2 mm asymmetry of the hight of the lateral lamella of the cribrifom plate, the Keros 3 group showed a statistical more common when compared to the other groups (X2=15.62, p=0.004). The hight of the lateral lamella of the cribrifom plate at the ipsilateral side (deviated side) was higher than that of the contralateral side, but the difference is not statistically significant. Conclusion: Understanding potential asymmetries and variations of the skull base contour may assist the surgeons in avoiding complications in sinus surgery. Key words: The ethmoid roof, sinus surgery

Olfactory fossa depth: CT analysis of 1200 patients

Background:Olfactory fossa (OF) is a depression in anterior cranial cavity whose floor is formed by cribriform plate of ethmoid. Lateral lamella, which forms its lateral boundary, is a thin plate of bone and is at risk of injury during functional endoscopic sinus surgery, especially when fossa is deep/asymmetric.Aims:To measure the variations in the depth of OF and categorize Kerala population as per Keros classification using computed tomography (CT).Settings and Design:This study was conducted in our institution from January 2016 to August 2017. Patients >16 years of age undergoing CT scan of paranasal sinuses (PNS) were included.Materials and Methods:Coronal PNS CT scan studies of 1200 patients were reviewed. The depth of OF was measured from vertical height of lateral lamella.Statistical Methods:Results were analyzed according to gender and laterality using independent sample t-test and Chi-square test.Results:The mean depth of OF was 5.26 ± 1.69 mm. Statistically significant difference was seen in the mean depth of OF between males and females but not between right and left sides. Keros type I was found on 420 sides (17.5%), type II in 1790 (74.6%), and type III on 190 sides (7.9%). Type III Keros was more on the right (9%) than left (6.8%) side, more in males (9.5%) than females (5.9%), and more among males on the right side (11.4%). Asymmetry in OF depth between two sides was seen in 75% of subjects.Conclusion:Prevalence of the dangerous type III OF, even though low, is significant especially among males and on the right side. Therefore, preoperative assessment of OF depth must be done to reduce iatrogenic complications.

Anatomical variations of the ethmoidal roof: differences between men and women.

During the paranasal sinuses surgery different complications may occur, both vascular and bony. The objective of the present study was to evaluate the ethmoidal roof configuration through the Keros and Yenigun classifications, analyzing results stratified by gender and side. We retrospectively analyzed 120 high-resolution computed tomography paranasal sinus study images and measured the depth of the cribriform plate in a coronal view and the anterior-posterior length in a cross section. The Keros Type II was the most frequent and no statistically significant difference was found when comparing by gender. Yenigun type I was more prevalent, and a statistically significant difference was found between men and women in types I and II (p = 0.010 and p = 0.049, respectively). Statistical difference was observed in anterior-posterior means in the comparison between both classifications. In both, right and left side for men (p = 0.003 and p = 0.05) and women (p = 0.029 and p = 0.039). We demonstrate the morphological variability that exists in this region. Gender differences that must be considered by the surgeon to avoid complications. Further studies are needed to evaluate the value of these findings when predicting surgical complications. A CT before PNS surgery is already widely accepted.

Anatomical variations of the ethmoidal roof: differences between men and women

IntroductionDue to the diverse variation of the ethmoid bone, we evaluated the roof using the Keros and Yenigun classifications, stratifying results by gender and side to determine difference.Materials and methodsParanasal sinus high‐resolution computed tomography were included from 2012 to 2017, excluding all those with pathologies that alter the anatomy of the region in study. The depth of the cribriform plate in a coronal view and the anterior‐posterior length in a cross section were measured for classification and analysis.ResultsA total of 120 high resolution CT were included. The Keros Type II and Yenigun type I were the most frequent, with only statistical difference between men and women in Yenigun types I and II (p = 0.010 and p = 0.049, respectively). Statistical difference was observed in anterior‐posterior means in the comparison between both classifications. In both, right and left side for men (p = 0.003 and p = 0.05) and women (p = 0.029 and p = 0.039)ConclusionMorphological variability exists in a Mexican population. Bone injury may be more likely in men and vascular injury in women due to their incidence of classification. Gender differences that must be taken into account by the surgeon to avoid such complications.Support or Funding InformationThere was no external funding. All funding provided by the department involved and medical school.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Study of Clinical Significance of the Depth of Olfactory Fossa in Patients Undergoing Endoscopic Sinus Surgery.

The endoscope has revolutionized the diagnosis and treatment of diseases of the nose and paranasal sinuses. Endoscopic sinus surgery (ESS), like all minimally invasive surgery, is designed to combine an excellent outcome with minimal patient discomfort. Successful outcome with minimal complications can only be achieved with good knowledge of the endoscopic anatomy, appropriate training in the procedure and the understanding of the anatomical variations. The intraoperative complications of ESS are bleeding and injury to surrounding structures commonly the orbital structures and fovea ethmoidalis. This is a hospital based prospective observational study with an objective to define the distribution of Keros classification of the depth of olfactory fossa and its asymmetrical distribution rates based on Keros type. Prospective study in a tertiary rural based hospital. 100 patients above the age of 10years from October 2013 to March 2015 for a period of one year six months undergoing endoscopic sinus surgery in the Department of ENT, P.E.S. Institute of Medical Sciences and Research, Kuppam were chosen randomly. The data was collected from these patients who will met the inclusion criteria of the study and before undergoing endoscopic sinus surgery by subjecting them to CT scan of paranasal sinuses. It is observed that a total of 100 patients had been studied in which the mean age of the population is 36.65+13.36years. Youngest patient was 12years old and eldest patient was 70years old. Among the patients 50(50%) were males and remaining 50(50%) were females with a female to male ratio is 1:1. In the present study, the depth of olfactory fossa ranged from 2.1 to 8.3mm inclusive of both sides in 200 CT images with a mean height of 5.21mm. Of the 200 sides measured, the distribution of Keros classification is as the following-Keros type I 39(19.5%), Keros type II 143(71.5%) and Keros type III 18(9%) sides. Based on these observations, type II is the most common Keros type prevalent followed by type 1 Keros type and the least prevalent is the type III Keros type in the studied population. In the present study, on considering sides separately, the right side olfactory fossa depth ranged from 2.1 to 8.3mm with a mean height of 5.43mm and the left side olfactory fossa depth ranged from 2.1 to 8.1mm with a mean height of 4.98mm. On the right side, of 100 sides measured, the distribution of Keros classification is as the following-Keros type I 19(19%), Keros type II 68(68%) and Keros type III 13(13%) sides. On the left side, of 100 sides measured, the distribution of Keros classification is as the following-Keros type I 25(25%), Keros type II 70(70%) and Keros type III 5(5%) sides. Based on these observations, type II is the most common Keros type prevalent followed by type 1 Keros type and the least prevalent is the type III Keros type in the studied population on both sides. In the present study, out of 100 patients 23 patients were having asymmetric olfactory fossa between right and left sides based on Keros type, where as remaining 77% had symmetric Keros type on right and left sides. Out of 23 patients, 16 patients were having lower or deep olfactory fossa on right side, where as remaining 7 patients were having lower or deep olfactory fossa on left side. Based on these observations, a lower or deep ethmoid roof occurred more frequently on the right side than on the left side. Wilcoxon matched pair signed rank test is applied to see the significant difference between depth of right and left olfactory fossae. Since P value is <0.001 the depth of olfactory fossa is significantly different from each other. The present study presents a precise, quantitative analysis of the olfactory fossa and ethmoid roof position as well as individual asymmetry. This information may be useful during pre-operative evaluation of CT images, as well as intraoperatively. The surgeon's understanding of the anatomy of a patient's ethmoid roof and its possible variations is crucial for countering possible complication risks during endoscopic sinus surgery.

International Frontal Sinus Anatomy Classification and anatomic predictors of low-lying anterior ethmoidal arteries.

The International Frontal Sinus Anatomy Classification (IFAC) was introduced to more accurately characterize ethmoid and frontal sinus pneumatization patterns. The prevalence of IFAC cells and their anatomic associations have not been described. The goal was to examine the prevalence of IFAC cells and determine radiologic features associated with a low-lying anterior ethmoidal artery (LAEA). Imaging of adult patients who underwent computed tomographies from January 2015 to March 2016 were retrospectively reviewed by using the IFAC classification. We also measured the distance from the skull base to the anterior ethmoidal artery (AEA), the height of the lateral lamella of the cribriform plate, and anterior-posterior diameter from the anterior wall of the frontal sinus to the skull base (APF). Patients with a history of sinus surgery, trauma, malignancy, or congenital anomaly were excluded. Statistical analysis was performed by using Pearson correlation coefficients and χ2 tests. A total of 95 patients met the inclusion criteria. There was a significant association between supraorbital ethmoid cells and an LAEA (p < 0.001), with a significant effect size (φ = 0.276, p = 0.007). An inverse relationship was observed between Keros type I classification I and an LAEA (p < 0.001), with a significant effect size (φ = -0.414, p = 0.000). Significant associations were found between the AEA distance from the skull base and the cribriform lateral lamella height (R = 0.576, p < 0.001). In addition, there was a significant association between the AEA distance from the skull base and the APF (R = 0.497, p < 0.001). The presence of a supraorbital ethmoid cell and a wide APF were associated with an LAEA. There was a significant relationship between Keros type I classification and the AEA adjacent to the skull base. Delineation of these anatomic relationships may be helpful during endoscopic sinus surgery to avoid complications.

Analysis of the Relationship between the Location of the Anterior Ethmoid Artery and Keros Classification.

Objective We sought to identify a relationship between skull base height and anterior ethmoid artery (AEA) anatomy. Study Design Retrospective radiologic chart review. Setting University of Arkansas for Medical Sciences. Subjects Patients seen in a tertiary rhinology clinic between September 2014 and October 2015. Methods Review of 101 maxillofacial computed tomography scans with institutional review board approval. Skull base height and AEA locations were measured on each side. Prevalence of the AEA outside of the skull base and distance of the AEA from skull base were calculated and compared with Keros classification using χ2 testing. Comparisons of skull base height between sexes and age and distance between skull base and the AEA among Keros 2 and Keros 3 patients were made using an unpaired, 2-tailed t test. Results The AEA was located below the skull base in 25.7% of cases and more often in Keros type 3 (55%) than in Keros type 2 (29.5%) or Keros type 1 (0%) ( P < .05). Male patients were significantly more likely to have a greater average skull base height (5.25 vs 4.28 mm) and to have AEAs below the skull base (38.4% vs 14.8%). In addition, the distance of the AEA from the skull base was significantly higher in Keros type 3 patients compared with Keros type 2 patients (4.55 vs 3.42 mm, P = .001). Conclusions Variations in the AEA pathway occur more in male patients and those with higher Keros classifications. The distance between the variant AEA and the skull base increases with higher Keros classification. Keros classification can yield insight to the location of the AEA.

Reliability of multidetector CT in the diagnosis of cerebrospinal fluid rhinorrhea with operative correlation

PurposeTo evaluate the role of non-contrast multidetector CT (MDCT) reliability in localizing CSF leaks and skull base defects in correlation to operative findings. Materials and methodsTwenty patients clinically diagnosed to have CSF rhinorrhea; 8 spontaneous and 12 post-traumatic patients were evaluated using 64-rows MDCT with slice section 0.6mm. CT is considered accurate if correctly determine the site and size of bony defect as matched with operative findings. ResultsMDCT accurately detected the site of presumed CSF leak in 19 out of 20 cases with sensitivity 95%. Cribriform plate defect is the most common site of defect in 40% of cases with 75% of cases categorized as Keros type II. The consensus image with fair agreement (K=0.38) shows that coronal reformat has the highest diagnostic performance in 75% of cases while the least diagnostic value is encountered with the axial plane in 15% of cases (p=0.095). There is almost a perfect agreement (K=0.810) between the MDCT measurements and operative size of bony defect with minimal difference in 10% of patients (P<0.001). ConclusionNon-contrast MDCT is an accurate reliable non-invasive imaging modality for preoperative evaluation of CSF rhinorrhea.

Is the Keros classification alone enough to identify patients with the ‘dangerous ethmoid’? An anatomical study

Conclusion: By means of three-dimensional display of the critical measurements, the authors suggest a novel definition of ‘dangerous ethmoid’. Parallel to Keros type III, the proposed determining factors include: olfactory fossa width >6 mm, its distance to the medial nasal concha (turbinate) <20 mm and to the orbit interval of <10 mm. Clinical evaluation of these preliminary criteria based only on radiological data is required and underway.Objectives: Detailed pre-operative assessment of sinus computer tomography (CT) scans reduces the frequency of severe complications in patients undergoing endoscopic sinus surgery (ESS). The authors aimed to identify a sub-set of anatomical features pre-disposing to major post-operative complications.Method: Sinus computer tomography (CT) scans of patients of a single institution qualified for ESS were examined. Besides the Keros classification, authors focused on the anatomic measurements as follows: the olfactory fossa depth, width, and its distance from the medial nasal concha and the medial wall of the orbit (referred to as ‘critical measurements’). The sample comprised 120 consecutive CT exams, without clinical validation.Results: Keros type I, II, and III was noted in 9.2%, 75.8%, and 15.0% of cases, respectively. Despite some statistically significant correlations, it was not possible to identify the patient age, sex, and side of body clearly correlating with the critical measurements.

ETHMOID ROOF RADIOLOGY; AN ANALYSIS OF 110 PATIENTS

We evaluated the extent of asymmetry evident in paranasal sinus computed tomography (CT) scans of Turkish patients without sinusitis in the ethmoid roof. Our data contribute to the body of knowledge on the subject. We retrospectively studied multiplanar reformatted CT images of the paranasal sinus (1-mm sections) from 110 patients (50 male, 60 female). Ethmoid roof variations on either side were compared and the lateral lamellar length of the cribriform plate was measured. The results were scored using the Keros classification. The lateral lamella of the cribriform plate averaged 5.78 mm in height on the right side and 5.98 mm on the left. The most common Keros type was type 2 (67.72%), followed by type 3 (22.28%), and type 1 (10%). Keros asymmetry (≥ 0.01 mm, affecting either side) was apparent in all patients (48.2% right-sided and 51.8% left-sided). Preoperatively, paranasal sinus CT scans should be evaluated carefully to eliminate the possibility of life-threatening complications, including intracranial trauma, which may develop during endoscopic sinus surgery; the left and right sides of the ethmoid roof may differ in depth.

Variations of the height of the ethmoid roof among Egyptian adult population: MDCT study

Fovea ethmoidalis and lateral lamella of the cribriform plate of ethmoid bone (LLCP) are the most vulnerable parts of the skull base for iatrogenic complication during functional endoscopic sinus surgery. Keros classified the depth of the olfactory fossa into 3 types. According to Keros, the greater the height of LLCP, the higher the risk of its iatrogenic injury. The aim of this study was to evaluate variations of the height of ethmoid roof among Egyptian adults using MDCT. Patients and methods: This study was conducted on 100 Egyptian adult patients referred for MDCT evaluation of PNS. Patients with any pathology involving the ethmoid roof were excluded from the study. MDCT machines were used for evaluation of all patients. Results: The mean age of our patients was 38.34±12.79years. The right lateral lamella height ranges from 0.50 to 10.0mm, while the left lateral lamella height ranges from 0.80 to 9.40mm. Keros type I was seen in 56.5%, type II in 40.5% and type III in 3%. Conclusion: The majority of studied Egyptian adult population showed Keros type I (56.5%) followed by type II (40.5%). Keros type III is seen in only 3% of studied adult Egyptian population.

Assessing the surgical anatomy of the ethmoid sinus in adult Nigerians using computerized tomography scan

We undertook this study to describe the morphology and anatomical variations of ethmoidal sinus in adult Nigerians using computerized tomographic scan, bearing in mind the significance of this sinus in inflammatory pathologies of the other paranasal sinuses and endoscopic sinus surgery. This was a descriptive study of computerized tomographic scans of the paranasal sinuses of 114 subjects constituting 228 ethmoids. All the slides were examined to identify the ethmoidal sinuses and the various anatomical variations. The dimensions of the ethmoids were also measured. There were 83 (72.8%) males in this study. The mean age was 45.6 ± 19.3 years. The means of the length, anterior width, posterior width and height of the ethmoid were 41.4, 11.8, 16.7 and 30.1 mm, respectively. Keros Type III olfactory fossa was found in 163 sides (71.5%). Agger nasi cell was the commonest variation present in 102 sides (44.7%). The most frequent pattern of attachment of uncinate process seen is to the lamina papyracea (191, 32%). We concluded that the dimensions of the ethmoids among the Nigerians studied are similar to findings in other studies. The predominant type of olfactory fossa depth and pattern of insertions of uncinate process suggest that the study population may be at higher risk of certain complications during functional endoscopic sinus surgery (FESS). Key words: Anatomical variations, olfactory fossa, Nigerians.

Is there an association between olfactory bulb volume and the Keros type of fossa olfactoria?

The purpose of this study was to investigate the relationship between the volume of the olfactory bulb (OB), the depth of the olfactory sulcus (OS), the depth of the fossa olfactoria (FO), and the height of the OB. A total of 54 patients participated (9 women and 45 men; mean [SD] age, 27 [38] y; range, 20-45 y). Magnetic resonance imaging was performed with a 1.5-T system (slice thickness, 1 mm). Measurements of the right and left OB volumes were performed through manual segmentation of the coronal slices. We measured the depth of the FO on the basis of Keros classification on coronal magnetic resonance images. The depth of the OS was measured on the coronal plane at the posterior tangent through the orbital globes. The height of the OB was measured on the coronal plane of the cribriform plate at the highest portion of the OB. The mean (SD) right OB volume was measured to be 52.21 (13.73) mm3 with a range between 33.90 and 95.70 mm3. The mean (SD) left OB volume was measured to be 53.98 (13.31) mm3 with a range between 31.20 and 94.10 mm3. Type 1, type 2, and type 3 Keros ratios of the FO bilaterally were 12.9% (7/54), 68.5% (37/54), and 3.7% (2/54), respectively. There was no significant relationship between the OB volume and ipsilateral Keros type of FO (right side: P = 0.208; left side: P = 0.164). Similarly, there was no significant relationship between the OB volume and depth of OS on both sides (right side: P = 0.073; left side: P = 0.065). There was no significant association between the Keros type of the right FO and depth of the OS (right side: P = 0.812; left side P = 0.863). We conclude that there is no statistical correlation between the OB volume and depth of the FO (Keros type). From the current study, it may be concluded that the depth of the FO may develop largely independent from OB volumes. The individuals without smell disorder have a wide range in OB volume. The method of OB volume measurement that we described is a valid measure of real OB volumes with high reproducibility.

Prevaléncia de variantes anatómicas naso-sinusales: Importancia en el informe radiológico y en la cirugía endoscópica funcional

Objective: To describe the prevalence in computed tomography (CT) of the main anatomical variations of the sino-nasal region, in a sample of the Chilean population, and to emphasize the importance of reporting them in the radiology report. Materials and methods: 100 paranasal sinus CT performed at our hospital were retrospectively evaluated. Each CT was evaluated by a neuro-radiologist and a third-year Radiology resident, recording the main anatomical variations of the structure and bone pneumatization of this region. Patients youn- ger than 18 yrs of age, and patients with significant distortion of the sino-nasal anatomy (e.g. tumors, history of facial fracture), were excluded. Results: The different anatomical variations were found in frequencies similar to those described in the international literature. The most common anatomical variation was deviated septum (83%), followed by the presence of Agger nasi cell (66%) and septal spur (45%). The upper attachment of the uncinate process was 68% in the lamina papyracea, 24% in the cribriform plate and 8% in the middle turbinate. Configuration of the ethmoid roof, according to the Keros classification, was 2% type I, 28% type II and 70% type III. The frequency of Keros type III ethmoid configuration was higher than that described in classical studies. The degree of sphenoid sinus pneumatization, according to the Hamberger classification, was 80% sellar, 19% presellar and 1% conchal. In 5%, dehiscence of the bone wall in relation to the carotid channel was recorded, one of these being bilateral. Conclusion: The study of paranasal sinus CT is useful to characterize the anato- mical variations of the sino-nasal region. A precise anatomical knowledge of this region is important; variations in the radiology report should be noted, especially if there is a plan to perform functional endoscopic surgery. Keywords: Anatomical variantions, Computed tomography, Sinuses.

An Analysis of the Anatomic Variations of the Paranasal Sinuses and Ethmoid Roof Using Computed Tomography

To determine the Keros classification and asymmetrical distribution rates of the ethmoid roof and the frequency of anatomic variations of the paranasal sinuses. Paranasal sinus scans of 500 patients obtained using computed tomography were evaluated retrospectively. Measurements were performed using a coronal plan with right-left comparison and with distance measurement techniques. The depth of the lateral lamella was calculated by subtracting the depth of the cribriform plate from the depth of the medial ethmoid roof. The results were classified according to their Keros classification. Any asymmetries in the ethmoid roof depth and fovea ethmoidalis configuration were examined. The anatomic variations frequently encountered in paranasal sinuses (pneumatized middle concha, paradoxical middle concha, agger nasi cells, Haller cells, Onodi cells, etc.) were defined. The mean height of the lateral lamella cribriform plate (LLCP) was 4.92±1.70 mm. The cases were classified as 13.4% Keros Type I, 76.1% Keros Type II, and 10.5% Keros Type III. There was asymmetry in the LLCP depths of 80% of the cases, and a configuration asymmetry in the fovea in 35% of the cases. In 32% of the cases with fovea configuration asymmetry, there was also asymmetry in the height of the right and left LLCP. The most frequent variations were nasal septum deviation (81.8%), agger nasi cells (63.8%), intralamellar air cells (45%), and concha bullosa (30%). Using the Keros classification for LLCP height, higher rates of Keros Type I were found in other studies than in our study. The most frequent classification was Keros Type II. The paranasal sinus variations in each patient should be carefully evaluated. The data obtained from these evaluations can prevent probable complications by informing rhinologists performing endoscopic sinus surgery about preoperative and intraoperative processes.

Asymmetry of lateral lamella of the cribriform plate: a software-based analysis of coronal computed tomography and its clinical relevance in endoscopic sinus surgery

Endoscopic sinus surgery is a known approach for sinonasal pathologies. Due to close proximity of sinuses to orbits and brain, surgeon should be aware of sinonasal anatomy and associated variations. The roof of ethmoid (fovea ethmoidalis) separates the ethmoidal cells from the anterior cranial fossa. Medially the fovea attaches to the lateral lamella of the cribriform plate, which is the thinnest bone of the skull base. Hence, it is at a high risk of getting damaged during surgery. To ascertain the quantitative analysis of height of lateral lamella according to Keros classification in the computed tomographic (CT) images of patients presenting to our clinic. It was retrospective review of 77 CT scans using computerized software known as picture archiving and communication system. The height of lateral lamella was examined for both sides and then classified according to Keros classification. Asymmetry between two sides was also reported. Keros type I was seen in 46 sides (29.8%), type II in 75 sides (48.7%) and type III was seen in 33 (21.4%) sides. Keros type I was seen in 38 sides in males and 8 sides in females. Type II was seen in 46 and 29 sides in males and females, respectively. Type III was seen in 18 sides in males and in 15 sides in females. Understanding of the anatomy of ethmoid roof with its possible variation is crucial to give the surgeon optimal information about the possible risk that one can face during the surgery. Hence dreadful complications can be avoided.

Analysis of Ethmoid Roof and Skull Base With Coronal Section Paranasal Sinus Computed Tomography

Chronic paranasal sinus disease is one of the most common causes of application to physicians in pediatric and adult patients. In the surgical treatment of these diseases, endoscopic sinus surgery is an application that is often done to increase the quality of the patient's life. On account of this, the anatomic variations in skull basement must be well known to avoid possible major complications that may occur during the operation. Recent developments in paranasal sinus surgery also enhanced the need for examining exhaustively the anatomy of this region and existing pathology. Superiority of computed tomography (CT) has an unquestionable importance for the evaluation of anatomic structure and pathology compared with conventional radiographs. A likely anatomic knowledge is needed for a safe surgery. Before the surgery, determining the anatomic variations makes the operation safer and increases the prospects, so we can prevent complications that may occur during the surgery. In this study, CT coronal sections of 300 patients who were admitted to the Department of Ear Nose Throat of Medical Faculty of Cumhuriyet University Research and Training Hospital between the dates December 2008 and January 2011 with complaints of nasal flow and postnasal drip were studied. According to coronal section CT examinations, the patients were divided into 2 groups. Group 1, with 156 cases (64%), showed mucosal changes, and in 144 cases (36%), no mucosal changes were established (group 2). In comparison between the sexes, in groups 1 and 2 females, significant difference was determined for other parameters except the average height of the ethmoid roof. In the comparison between the sexes, in groups 1 and 2 males, significant difference was determined for all parameters. The difference between these 2 rates was statistically significant. Keros types 1 and 2 cases were compared with the control group, and there was no statistically significant difference. Notwithstanding, at the comparison of the Keros type 3 with the control group, there was a statistically significant difference for all the parameters (maximum orbital height, the length of the middle concha, and the nasal wall). It seems to be important for us to know the average length of the peripheral anatomic structures to avoid serious complications that may occur during the operation. Careful preoperative review of paranasal sinus CT scans in patients undergoing sinus surgery seems to be the most important to prevent severe intraoperative complications.

Age-dependent differences of the anterior skull base

ObjectiveImaging of the anterior skull base and paranasal sinuses is essential before surgery of the nose and paranasal sinuses. It is important to know individual anatomical variations to define a “dangerous ethmoid” to prevent complications such as considerable bleeding or injury to the brain. This study aimed to analyze the relevant parameters with special regard to age-dependent differences. MethodsThis was a retrospective, single center study of 865 patients. Data from cone beam computed tomography (CBCT) of 116 patients less than 18 years of age and 749 adult patients were analyzed. Keros type, the course of the anterior ethmoid artery, the course of the uncinate process and the angle between the lateral lamella and the cribriform of the olfactory fossa were evaluated. ResultsDifferent frequencies of the course of the uncinate process between young and adult persons could be shown: onset at the lamina papyracea 67% vs. 64%; onset at the skull base, 22% vs. 26%; and onset at the middle turbinate, 11% vs. 10%. Differences in the course of the anterior ethmoid artery could be evaluated in the same way: course at the skull base, 49% vs. 44%; free course with a distance to the skull base of less than 3mm, 11% vs. 19%; and free course with a distance to the skull base more than 3mm, 40% vs. 37%. Significant differences could be found in the frequencies of the height of the olfactory fossa: Keros type I, 28% vs. 16%; Keros type II, 51% vs. 60%; and Keros type III, 21% vs. 24%. The angle between the lateral lamella and the cribriform plate showed significant differences dependent on the course of the anterior ethmoid artery (skull base=123° vs. distance<3mm=117° vs. distance>3mm=110°) and dependent on the height of the olfactory fossa (Keros type I=135° vs. Keros type II=117° vs. Keros type III=104°). Analysis of the angle as a factor of age and Keros type showed a significant difference in Keros type I (125° vs. 132°) and Keros type II (105° vs. 110°). ConclusionCone beam computed tomography (CBCT) of the anterior skull base allows the assessment of individual anatomical-radiological risk profiles and the identification of a “dangerous ethmoid”. Significant age-dependent differences in the frequencies of anatomic landmarks and the angles of the ethmoid roof could be evaluated and led to significantly different risk profiles between children and adults.

Radiological analysis of the ethmoid roof in the Malaysian population

To ascertain the prevalence of the lateral lamella of the cribriform plate height according to Keros classification in the Malaysian population, and to find if there is any difference between the major ethnic groups in Malaysia (Malay, Chinese, Indian). Retrospective analysis of 150 CT scan studies of the paranasal sinuses. The mean height of the lateral lamella of the cribriform plate (LLCP) in 300 sides was 2.64mm. Keros type I was seen in 240 sides (80%), while, Keros type II was seen in 60 sides (20%). There was no significant difference in the distribution of Keros classification among the major ethnic groups of Malaysia (Malay, Chinese, Indian). Keros type I was seen in 103 sides in males and 137 sides in females. Significant difference was observed in type II between the male and female (47 sides in males and 13 sides in female; p-value <0.001). When comparing the difference in the height of the LLCP in the same individual, asymmetry was observed in 139 patients. The LLCP height was higher on the left side in 71 patients and higher on the right in 68. The understanding of the anatomy of the ethmoid roof with its possible variation is crucial to give the surgeon the optimal information about the possible risk that one can face during the surgery.

Analysis of the fossa olfactoria using cone beam tomography (CBT)

Conclusion: A cone beam tomography (CBT) examination of the olfactory area with its different variants allows development of an individual anatomical-radiological risk profile of the ethmoid and the identification of so-called ‘dangerous ethmoids.’ Objective: Preoperative imaging performed with high-resolution CBT is imperative for analysis of the risk of injuring the olfactory fossa during sinus surgery. This study aimed to analyze the relevant parameters. Methods: This was a retrospective, single-center study of 141 patients. The Accu-I-Tomo F17 was used. Keros type, the point of the anterior ethmoid artery, and the angle between the lateral lamella and the cribriform plate (αlc) were evaluated. Results: The Keros types were distributed as follows: type I, 13% (αlc: 131°); type II, 64% (αlc: 116°); type III, 23% (αlc: 108°) (p < 0.001). The angle of the olfactory fossa and the position of the anterior ethmoid artery (free course: αlc=112° vs integrated into the skull base: αlc= 120°) was significantly different. Discussion: Surgical procedures in Keros type III where the height of the lateral lamella is much longer than in type II or type I, with an angle of nearly 107° between the lateral lamella and the cribriform plate, are expected to be safer in comparison with Keros type II with 116° and Keros type I with 131°.