الفهرس 
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Abstract
The paranasal sinuses are air-filled spaces located within the bones of the skull and face. They are centered on the nasal cavity and have various functions, including lightening the weight of the head, humidifying and heating inhaled air, increasing the resonance of speech, and serving as a crumple zone to protect vital structures in the event of facial trauma. Four sets of paired sinuses exist: maxillary, frontal, sphenoid, and ethmoid.
The anatomy of paranasal sinuses is complex and in many circumstances confusing. The anatomical variants of the sinonasal cavity impose a further challenge due to their further complexity and various types and forms.
Frontal sinus anatomy can be challenging even for the most experience surgeon. A thorough knowledge of the most common normal variants is critical in order to safely navigate through the nose during endoscopic sinus surgical procedures and avoid complications.
A series of “accessory” ethmoidal cells may line the frontal sinus outflow tract along the frontal recess and infundibulum, which are collectively known as frontal recess cells. . These cells are normal anatomic variants that are present in some combination in most individuals. They not only can alter the normal sinus drainage if inflammatory conditions are present, but also if an endoscopic surgeon not aware of these cells this might result in a surgical failure.
The frontal sinus can also be confused with “frontal infundibular cells”. These represent a series of anterior ethmoidal cells directly superior to the agger nasi cell, coursing along the anterior wall of the frontal outflow tract. Bent and Kuhn have divided frontal infundibulum cells into four categories, based on their relationship to the agger nasi cell and the orbital roof. Types 1-3 are all located above the agger nasi cells: Type 1 is defined as a single anterior ethmoid cell within the frontal recess above the agger cell. Type 2 Is defined as a strand of two or more anterior ethmoid cells above the agger nasi cells. Type 3 is a single cell located above the agger nasi but that extends superiorly from the recess, through the ostium, up to the frontal sinus and pneumatizes into it with occupation of nearly 50% of the sinus. Type 4 is a single isolated cell that exists completely within the frontal sinus and has no connection to the frontal recess. It is confined at an anterior level by the anterior frontal table. The posterior wall of these cells is the free partition in the frontal sinus.
The introduction of head and neck MDCT imaging and the current wider use of this modality have definitely helped the clinician. MDCT has become a useful diagnostic modality in the evaluation of the paranasal sinuses and an integral part of surgical planning. Today, MDCT is the radiologic examination of choice in evaluating the paranasal sinuses of a patient with sinusitis.
The purpose of the current study focused on the assessment of the role of MDCT in the assessment of the effect of different anatomical types of frontal air cells on the occurrence and severity of frontal sinusitis.
The study was conducted on one hundred patients.Fifty patients (group A) had complain of frontal sinusitis. Another fifty patients (group B) had MDCT of head and neck due to other reasons as headache, epistaxis, orbital pain, hearing problems, etc. They had no complain related to sinusitis. Each case had 2 sides (right and left). Each side was considered as a separate entity. If we were dealing with age or sex, they would be 100 cases. If we were dealing with types of frontal air cells, sinusitis or Lund Mackay score for severity, it would be 200 sides.
The study included 44 males and 56 females, the age of patients ranged between 18 and 60 years, with a mean of 32.5 years.
It was noticed that the largest number of patients was found in the (above 20 and below 30 years) age group in both groups.
The highest number of cases with sinusitis in group A was in the 2nd age group (20-<30) that was 17. Bilateral sinusitis was more in same previous age group. . In group B, the highest number of patients with sinusitis was also in the 2nd age group (20-<30) that was 21. Bilateral sinusitis was more in the 3rd age group (30-<40).
In group A, The most common type presented in males was type II, while the most common type presented in females was type I. . Totally the most common type presented in this group was type I. In group B, the most common type presented in males was type III; while the most common type presented in females was type I. Totally the most common type presented in group B was type III.
The agger nasi is generally considered to be the most constant cell in the frontal recess and was found in 60% in group A, 86% in group B and 73% in the total.
The prevalence of frontal cells in the current study was 55% (55 sides) in group A, 69% (69 sides) in group B and 62% (124 sides) in the total studied population.
It was found in group A that sides those had frontal cells with sinusitis were 46 (83.6%) sides. Those had no sinusitis were nine sides (16.4%). While sides that didn’t show frontal cells and had sinusitis were five sides (71.5%). Those had no sinusitis were two (28.5%). The P value of this relation was 0.597 which means that the presence or absence of frontal cells doesn’t affect the occurrence of sinusitis (no significance).
In group B we found that sides those had frontal cells with sinusitis were 25 (36.2%). Those had no sinusitis were 44 sides (63.8%). While sides that didn’t show frontal cells and had no sinusitis were 26 sides. The P value of this relation was (<0.001) which means that is statistically significant. So we conclude that the presence of frontal cells in this non complaining group resulted in increasing the occurrence of sinusitis.
Regarding the relation between the complain and the occurrence of sinusitis. We found that the group who was complaining from sinusitis (group A) was 43 patients (86%) out of 50 patients. They had CT evidence of sinusitis. Only seven patients (14%) had no CT evidence of sinusitis. The group who wasn’t complaining from sinusitis (group B) was 15 patients (30%) out of 50 patients. Those had CT evidence of sinusitis. Thirty five patients (70%) had no CT evidence of sinusitis. The P value was (<0.001) which means that it is statistically significant. So we conclude that CT evidence of sinusitis can be found in non complaining.
The type that had the highest frequency in group A and in the total was type I. The type that had the highest frequency in group B was type III. The least type in occurrence in group A, group B and the total was type IV with the percentage of 2.5%. We found that in group A, (9.7%) had score 0. Score 1 was present in (48.4%). Score 2 was present in (41.9%). While in group B, (59.5%) had score 0. Score 1 was present in (33.8%). Score 2 was present in (6.8%).
During interpretation of cases we found that there were cases that had two types of frontal cells at the same time on one or both sides; were categorized under specific entity ”combined”. They were 17 sides (8.5%) from the total of 200 sides. The combinations of the highest frequencies were types I, III and II, III equally. Each was found in five sides.
Also there were cases that had no frontal cells; were categorized ”Not identified ”category. They were seven (7%) in group A and 26 (26%) in group B. with a total of 33 (16.5%) in all studied sides.
Lund-Mackay scoring is a system that we used to classify and determine the severity of sinus mucosal inflammation or fluid accumulation as following: 0 (complete lucency), 1 (partial lucency) or 2 (complete opacity).
It was noticed that there were a problem to identify the exact type of frontal cells in cases that had sever sinusitis with score ”2” Lund Mackay. The total opacification of cells made it difficult to identify the shape, number or outline of frontal cells so were categorized ”Couldn’t be assessed” category. They were 38 (38%) in group A and five (5%) in group B with a total of 43 (21.5%) in all studied sides.
In our study we noticed that type I cells had the highest occurrence of sinusitis (16 sides) in group A. while in group B, type III had the highest occurrence of sinusitis (9 sides).
In group A the highest occurrence of sinusitis was in the bilateral form which was (70%) then the right side involvement (16%). In group B the predominance was for the unilateral involvement which was (36%) with (18%) for each side. In all the studied cases the predominance was for the bilateral involvement (41%).