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SUMMARYThe paranasal sinuses include four pairs, ethmoid frontal, maxillary, and sphenoid sinuses. These sinuses have great number of anatomical variation between individuals and even in the same individual there is variation between the right and the left side. The use functional endoscopic sinus surgery (FESS) in treatment or diagnosis of sinusitis or both require a good knowledge of the complex anatomy of paranasal sinuses and the variation of this anatomy.aim of the workGive radiological anatomical view of the sinuses.Describe the radiological anatomical variations which could be observed at each sinus.1) CasesThis study comprised 180 CTs of paranasal sinuses from patients whom were free from chronic sinusitis. The cases were explored at multiple radiological sites in the Radio-diagnostic Unit Zagazig University Hospital.The cases were divided into two main groups:Group A: 90 male. The age of them ranged from 17 to 75 yearsGroup B: 90 females. The age of them ranged from 18 to 70 years.Each group was subdivided according to age into three subgroups each subgroup contains 30 cases:Subgroup/ I: age from 17 in male or 18 in female to 39 years.Subgroup/ II: age from 40 to 59 yearsSubgroup/ III: age > 60 years.2-MethodsSystemic and local examinations were done before scanning for each case to exclude the diseased sinuses. . Each case was subjected to both coronal and axial CT scans. The position of the case was supine in axial scans. In coronal scans the case position may be supine with hyper extended neck or prone with hyper extended neck depending on the case.The coronal CT scans:Coronal CT scans were made from the anterior wall of the frontal sinus to the posterior wall of the sphenoid sinus. Contiguous 5 mm slice thickness is recommended to avoid loss of any bony details. Gantry angle was perpendicular to the hard palate as possible as can.Axial scan :The extent of axial scan was from alveolar margin of the maxilla inferiorly to upper limit of the frontal sinus (supra-sellar) superiorly.The Gantry angle was parallel to orbito-meatal line.In both axial and coronal scans the window and level were adjusted to be suitable for imaging bony details, air passages and soft tissue .Each variant was expressed as ratio. This ratio was compared between the males and females .Each ratio was compared between the different age groups to detect the possible effect of the aging process on the sinuses. Comparison between the right and the left side in the same individual is also discussedMeasurements of both transverse and anteroposterior diameters These measurements were taken for each sinus. These measurements were collected and statistically analyzed for detection of: Difference between the right and the left sides Difference between the males and females. Correlation between these different dimenations and ages.Ethmoid sinusThe ethmoid sinus is the commonest one of the paranasal sinuses that affected by variations. This sinus by coronal CT is observed as several superimposed structures arranged in anteroposterior direction. It has variation in each structure. The ethmoid sinus contains the anterior group which located in front (anterior) and drains in the middle meatus anterior to the basal lamella. The posterior group is located behind basal lamella and drains in the superior meatus. From the anterior ethmoidal group the bulla ethmoidalis (which is the laergest one) and the agger nasi cells were dectecd.Also there were important cells that have special clinical importance. These cells are Haller’s cells and Onodi cells.The Haller’s cell lied in the region of ethmoid infundibulum. It lied in the medial part of the roof of maxillary sinus and infero-medial wall of the orbit, inferior of the ethmoid bulla and lateral to the uncinate process .The Haller’s cells were present in 14.4 cases 8.3% in males and 6.1% in femalesOn the other hand the Onodi cell was present antero-lateral to the sphenoid sinus area in the most posterior part of the ethmoid sinus. In these cases the optic nerve was detected bulging into the Onodi cell. The cells were present in 7.8% cases in both groups ; 5% in males and 2.8% cases in female .Symmetry, Gender and correlation with age:As regards symmetry of the ethmoid sinus, the current result showed that there was no significant difference between anteroposterior or transverse diameters of ethmoidal sinuses on both sides. Concerning the comparison with gender the present study found that there was highly significant decrease in transverse diameter on both right and left sides in females when compared with males .There was also significant decrease in the left anteroposterior diameter in females when compared with males.Correlation of diameters of ethmoid sinus on both sides with age reveals that there was insignificant negative correlation between these diameters and age.The frontal sinuses:The frontal sinuses showed a great number of variations .This sinus was highly variable between the studied cases. The normal radiological anatomy of this sinus was described. Unilateral aplasia of the frontal sinus was detected in 6.1% of studied cases (5.5% on the left side and 0.6% on the right side).The sinuses also showed different septal variations (deviation, deficiency, S-shape).central septum was obsereved in 22.2% of cases. Deviated septum towards the right side was obsereved in 45% of the studied cases .Deviated septum towards the left side was observed in25.6% of the studied cases.The accessory cells (supraorbital and intersinus septal cells) were detected also in the frontal sinus.The supraorbital cell was detected in this study in 7.8% of casesThe intersinus septal cell is an air cell that pneumatize the septum between the two frontal sinuses. The present study observed the intersinus septal cell in 5% of studied cases(2.8%males and 2.2% females).Symmetry, Gender and correlation with age: As regards symmetry, the finding of this work showed that was significant decrease of the right transverse diameter when compared with the left one (pAs regards gender it was found that the frontal sinus is larger in male than female. Correlation of diameters of the frontal sinus on both sides with age reveals that there was insignificant positive correlation between these diameters and age (p>0.05).Maxillary sinuses:The normal radiological anatomy of these sinus was described .The different degrees of pneumatization were observed (average, over and hypo). A number of variations (septation and accessory, ostia) affecting these sinuses was observed. The accessory ostia detected in this study in 12.8% (5.6% males and 7.2% females) . The hypoplastic maxillary sinus was detected in 23.8% of studied cases(10% males and 13.8% females)Septated maxillary sinus wsa present in five percent of cases in the present study (2.2% males and 2.8% females).Symmetry, Gender and correlation with age:As regards symmetry, our result showed that there was no significant difference between anteroposterior or transverse diameters of maxillary sinuses on both sides (p> 0.05). As regard the gender in the present study there was insignificant change in all diameters of the maxillary sinuses both right and left sides in female when compared with male (p>0.05) except the left anteroposterior.This diameter showed significant decrease in females when compared with males (pCorrelation of diameters of maxillary sinuses on both sides with age reveals that there was significant positive correlation between these and the age.Sphenoid sinuses:The normal radiological anatomy of these sinuses was observed in both axial and coronal views.The different degrees of pneumatization were observed (average, over and hypo) were observed..The septal variations (central, deviated, S-shape and deficiency) were also observed.central septum was observed in 13.4%.of the studied cases. Deviated septum towards the right side was observed in 26.7% of male and 21.7% of female cases. Deviated septum towards the left side was observed in 16.1%% of of male and 13.8%.of female cases. A number of other variations was observed the most important variations were the pneumatization of anterior clinoid process(s) and pterygoid process (s).Symmetry, Gender and correlation with age: As regards symmetry, the results of the present study showed that there was no significant difference between anteroposterior or transverse diameters of sphenoid sinuses on both sides (p> 0.05). As regard the gender the present study found that there was insignificant change in the sphenoid sinuses in transverse or antro-posterior diameter on both right and left sides in females when compared with males (p>0.05). In the present study the correlation of diameters of sphenoid sinuses on both sides with age reveals that there was significant negative correlation between anteroposterior diameter on the right side only and age (pConclusionFrom the above mentioned study we can concludes the following; The human paranasal sinuses are clearly studied by CT for description of the normal radiological anatomy in the living subjects. The fine bony details of this anatomy and its complicated nature are also clearly seen. There are racial factors affect this variations. There is difference between the prevalence of the variations between this study and other studies. There are some variations observed in this study not mentioned in the other studies. The ethmoid, sinus has special nature characterizes it from the other paranasal sinuses. It is observed as several lamellae. It is the most complicated one of the paranasal sinuses. As its name denote it is a labyrinth. The frontal sinus has a special pattern for each individual. The sphenoid sinus is affected by variations which cause vulnerability of the optic nerve and the internal carotid artery during the infection or the surgery of this sinus. The maxillary sinus is the least variable sinus. The CT scans especially the coronal is excellent preoperative investigation for the surgeon to be familiar with the paranasal sinuses’ region and also it help in identification of the anatomical variations.
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