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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 18  |  Issue : 2  |  Page : 152-158

The relationship between ethmoid roof and cribriform plate dimensions and degree of septal deviation angle by computerized tomography


1 Department of Otorhinolaryngology, Faculty of Medicine, Al-Azhar University, Cairo, Egypt
2 Department of Radiodiagnosis, Faculty of Medicine, Al-Azhar University, Cairo, Egypt

Date of Submission31-Mar-2020
Date of Decision13-Apr-2020
Date of Acceptance14-May-2020
Date of Web Publication24-Jul-2020

Correspondence Address:
MD Lecturer of Radiodiagnosis Mahmoud I Elshamy
Radiodiagnosis Department, Faculty of Medicine (for boys) Al-Azhar University, 5th Settlement, Narges 3, Villa 94, Flat 4, Cairo, 11865
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/AZMJ.AZMJ_61_20

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  Abstract 


Background Endoscopic sinus surgery (ESS) is a common operation for the management of sinonasal pathologies. The surgeons dealing with ESS should understand the crucial complex anatomy of the anterior cranial base to avoid the intracranial violation during ESS.
Objective The aim of this work was to investigate the relationship between degree of septal deviation angle and the dimensions of cribriform plate (CP) and ethmoid roof by evaluation of the paranasal computed tomography.
Patients and methods A total of 40 patients, comprising 20 females and 20 males, with age ranging from 18 to 60 years, were selected according to inclusion and exclusion criteria from the outpatient ENT clinics of El-Hussein and Bab-El-She’reya Hospitals from November 2017 to January 2019.
Results The severity of deviation did not affect the dimensions of the ethmoid roof and CP in terms of depth and width, except right ethmoid roof width (direct proportion) and the left cribriform width (inverse proportion). There was a significant direct relationship between ipsilateral and contralateral ethmoid roof (ER) width and between ipsilateral and contralateral ER depth. This study showed no significant relation between ipsilateral and contralateral CP width. High rate of asymmetry between CP and ethmoid roof in this study (100%) was noted.
Conclusion In cases of deviated nasal septum, the increase in the severity of septum deviation raises the possibility of the increasing right ethmoid roof width and of decreasing the left cribriform width, and this possibility should be taken into consideration to avoid iatrogenic injury during ESS.

Keywords: cribriform plate dimensions, degree of septal deviation angle, ethmoid roof


How to cite this article:
Elgalil AS, Elshamy MI, Yonis MA, Eldiehy IM. The relationship between ethmoid roof and cribriform plate dimensions and degree of septal deviation angle by computerized tomography. Al-Azhar Assiut Med J 2020;18:152-8

How to cite this URL:
Elgalil AS, Elshamy MI, Yonis MA, Eldiehy IM. The relationship between ethmoid roof and cribriform plate dimensions and degree of septal deviation angle by computerized tomography. Al-Azhar Assiut Med J [serial online] 2020 [cited 2020 Aug 10];18:152-8. Available from: http://www.azmj.eg.net/text.asp?2020/18/2/152/290606




  Introduction Top


Radiological evaluation of the ethmoid roof is important in preventing the endoscopic sinus surgery (ESS) complications. Iatrogenic lesions of the anterior skull base can occur in the ethmoid roof and the cribriform plate (CP) [1].

The relationship between CP dimensions (height or width) and other paranasal structures such as frontal sinus pneumatization, pneumatized middle turbinate, and nasal septum deviation was investigated by several researchers in the relevant literature [2].

However, the relationship between septal deviation (SD) and CP dimensions has not been evaluated so far. Among studies, a study done by Saylisoy et al. [3] observed that when SD angle is increased, ipsilateral and contralateral CP width and depth are increased.

Understanding the complex anatomy of the paranasal sinuses is crucial to surgeons to avoid the intracranial violation during ESS [4].

Inadvertent violation of the CP or the ethmoid roof may result in intracranial injury, cerebrospinal fluid rhinorrhea, and a consequent increased risk of developing meningitis [5].

Between the two CPs, there are two central vertically disposed midline processes of ethmoid bone, where the superior is the crista galli, and the inferior is the perpendicular plate that makes a substantial contribution to the nasal septum, which divides the nasal cavity into two separate chambers [2].

The SD is defined as convexities of the nasal septum on one side with accompanying deformities of midline structures [6].

The development and refinement of computerized tomography (CT) imaging has allowed detailed assessment of not only the sinonasal diseases but also the characterization of the paranasal sinuses anatomy. It is important for the surgeon to look at the CT scan preoperatively to get an idea of the anatomy and to relate the changes revealed on the CT scan to the patient’s clinical condition [7].


  Aim Top


The aim of this work was to investigate the relationship between degree of SD angle and the dimensions of CP and ethmoid roof by radiological paranasal CT evaluation.


  Patients and methods Top


This prospective study was carried out at the Otorhinolaryngology and Radiology Departments of Al-Azhar University Hospitals.

A total of 40 patients, comprising 20 females and 20 males, were selected according to inclusion and exclusion criteria from the outpatient ENT Clinics of El-Hussein and Bab El-She’reya Hospitals from November 2017 to January 2019. Their age ranged from 18 to 60 years old.

Inclusion criteria were as follows:
  1. Age: patients were between 18 and 60 years old.
  2. Sex: both sexes (males and females) were included.
  3. Race and ethnicity: to overcome the racial and ethnic problem and its effect on the skull configurations, we confined our work to the adult Egyptian population.
  4. Nasal septum deviation with or without symptoms.
  5. Paranasal sinuses with intact olfactory fossa and ethmoid roof.


Exclusion criteria were as follows:
  1. Patients younger than 18 years old and older than 60 years old.
  2. Previous sinus surgery, septoplasty, turbinoplasty, rhinoplasty, or sleep apnea surgery.
  3. Septal perforation.
  4. Craniofacial syndrome.
  5. Systemic diseases, for example, sarcoidosis and Wegener’s granulomatosis.
  6. Pregnancy.
  7. Previous facial trauma.
  8. Marked facial deformity
  9. Sinonasal polyposis.
  10. Rhinosinusitis.
  11. Cerebrospinal fluid leak.
  12. Sinonasal tumor.
  13. Head and neck tumors.
  14. Radiation therapy to the head and neck.


Written informed consent

An approval of the study was obtained from Al-Azhar University Academic and Ethical Committee. Every patient signed an informed written consent for acceptance of the operation.

Procedure

All patients were subjected to the following protocols:
  1. Careful history taking: personal history, complaint and history of the present illness, and past history.
  2. Routine physical ear-nose-throat examination: focusing on detailed nasal examination, ENT examination included ear, larynx, and oral cavity.
  3. Radiological examination of the nose: imaging CT scans of nasal and paranasal sinuses.


Methods

All patients were evaluated by clinical examination, nasal endoscopy, and CT imaging.

Nasal septum assessment by endoscopy

In the study, 0° and 30° 4-mm rigid nasal endoscopes were used for the following:
  1. To assess the anatomy in the neutral position, and it also allows inspection of the elements that are not visible in anterior rhinoscopy; this at times can reveal adenoid tissue, mucosal abnormalities, nasal polyps, or choanal pathology, which can affect the study.
  2. To exclude inferior turbinate hypertrophy, presence of nasal secretions, and nasal mass such as polyp.


CT imaging

CT examinations were performed by Activion 16 CT Scanner (2008; Toshiba Medical Systems, Tochigi, Japan) (kVp=150, mAs=150, slice thickness=3 mm) and GE 4 detector CT Scanner (GE Health Care) at El-Hussein University Hospital.

For more accurate measurement, different workstations (Vitrea 5.2.487.4267 at Bab El-She’reya Hospital and Paxera ultimate 360 at El-Hussein Hospitals) were used.

Three points were chosen as reference points at the skull base:
  1. The lateral ethmoid roof point, which is identified by the intersection of a vertical line tangent to the medial orbital wall with the ethmoid roof.
  2. The medial ethmoid roof point (MERP), which corresponded to the articulation of horizontal/slope part of anterior skull base with the lamina lateralis of the CP.
  3. CP.


The distance between these two roof points (lateral ethmoid roof point and MERP) is defined as ‘width of anterior ethmoid roof’.

The distance between crista galli and MERP is defined as ‘width of CP’ ([Figure 1],[Figure 2],[Figure 3],[Figure 4]).
Figure 1 Endoscopic nasal examination shows septal deviation to left side.

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Figure 2 Coronal computed tomographic scan demonstrating the lateral ethmoid roof point (long arrow), medial ethmoid roof point (short arrow), the distance of these landmarks to the horizontal plane of nasal cavity (LH: lateral ethmoid roof point height, MH: medial ethmoid roof point height and CH: cribriform plate height), the width of cribriform plate (asterisk), and the width of anterior ethmoidal roof (A) at the first coronal section of which is infraorbital nerve determined (curved arrow) [8]. CH, cribriform plate height; LH, lateral ethmoid roof point height; MH, medial ethmoid roof point height.

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Figure 3 Measurement of septal deviation angle by Paxera ultimate 360 workstation software.

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Figure 4 Measurement of dimensions of ethmoid roof and cribriform plate by Paxera ultimate 360 workstation software.

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Statistical analysis

Recorded data were analyzed using the Statistical Package for the Social Sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean±SD. Qualitative data were expressed as frequency and percentage.

The following tests were done:
  1. Independent-samples t-test of significance was used when comparing between two means.
    • χ2-test of significance was used to compare proportions between two qualitative parameters.
  2. The confidence interval was set to 95% and the margin of error accepted was set to 5%. The P value was considered significant as follows:
    1. P value less than 0.05 was considered significant.
    2. P value less than 0.001 was considered as highly significant.
    3. P value greater than 0.05 was considered insignificant.



  Results Top


This study included 40 patients with deviated nasal septum, comprising 20 (50%) females and 20 (50%) males, with age ranging from 18 to 60 years (mean 31.9±12.88 years).

A total of 20 (50%) patients were deviated to the right side and the other 20 (50%) patients were deviated to the left side.

According to the side of deviation, mean age of deviated septum to the right side was 30.1 years and to the left side were 33.7 years.

SD to the right side was more in females (60%, 12 cases) whereas in males was 40% (8 cases), and SD to the left was more in males (70%, 14 cases), whereas in females was 30% (6 cases) ([Table 1]).
Table 1 Comparison of age and sex regarding the side of deviation

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[Table 1] shows no significant statistical influence (P>0.05) of age and sex on the side of deviation.

[Table 2] shows no significant statistical difference between ipsilateral and contralateral sides regarding CP and ethmoid roof dimensions.
Table 2 Comparison between ipsilateral and contralateral sides regarding cribriform plate and ethmoid roof dimensions

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[Table 3] shows no significant statistical difference between right and left sides regarding CP and ethmoid roof dimensions.
Table 3 Comparison between right and left sides regarding cribriform plate and ethmoid roof dimensions

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Pearson correlation coefficient (r) test results

  1. Between SD angle degree and ethmoid roof dimensions:
    1. There was a positive correlation between the degree of SD angle and right ethmoid roof width, and this means if the angle increases, the right ethmoid roof (ER) width increase.
    2. There was no significant statistical correlation between the degree of SD angle and other ethmoid roof dimensions in the studied patients ([Table 4]).
      Table 4 Correlation study septal deviation angle degree and ethmoid roof dimensions in studied patients (r): Pearson correlation coefficient

      Click here to view
  2. Between SD angle degree and CP dimensions:


      There was a negative correlation between the degree of SD angle and the left CP width, and this means if the angle of deviation increases, the left CP width decreased.

      There was no significant statistical correlation between the degree of SD angle and other CP dimensions in studied patients ([Table 5]).
      Table 5 Correlation study septal deviation angle and cribriform plate dimensions in studied patients

      Click here to view
  3. Between the same ethmoid roof dimension in both sides: there was a high significant statistical positive correlation between right ethmoid roof width vs. left.


There was a statistically significant positive correlation between right ethmoid roof depth vs left. ethmoid roof depth. There was a statistically significant positive correlation between ipsilateral ethmoid roof (deviated side) width and contralateral ethmoid roof width. There was a statistically significant positive correlation between ipsilateral ethmoid roof (deviated side) depth and contralateral ethmoid roof depth ([Table 6]).
Table 6 Correlation study the same ethmoid roof dimension in both sides

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Between the same cribriform plate dimension in both sides

There was an insignificant positive correlation between right CP width vs left CP width.

There was a high statistical significant positive correlation between right CP depth vs left CP depth.

There was an insignificant positive correlation between ipsilateral CP (deviated side) width and contralateral CP width.

There was a statistically significant positive correlation between ipsilateral CP (deviated side) depth and contralateral CP depth ([Table 7]).
Table 7 Correlation study the same cribriform plate dimension in both sides

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  Discussion Top


This study included 40 patients with deviated nasal septum, with equal incidence in male and female (50 and 50%, respectively). It is consistent with the study done on 284 patients by Ibrahim et al. [9], which found an equal incidence in male and female (50.4 and 49.6%, respectively).

Ozkurt et al. [10] found 65% of deviated nasal septum with relatively more male predominance in their study on 212 patients, but this predominance has no significant difference between men and women [11].

In this study, the age range was 18–60 years, with a mean age of 31.9 years, and the selection of this age group indicates that deviated nasal septum is common in adults. Gray [12] found that deviated nasal septum was 30% in children and 80% in adults. van der Veken et al. [13] found that deviated nasal septum incidence is up to 70%, with increasing incidence with age.

The nasal septum may be deviated to the right or to the left side, Cumberworth [5] proposed that the nasal septum deviates to the right side, but Buyukertan et al. [14] stated that the nasal septum is usually deviated to one side or the other, most often without definition which side is more. Saylisoy et al. [3] observed that right SD was more (58% of the patients). In this study, the SD was equally deviated to both sides (50% to the right side and 50% to the left one).

The measured angles of nasal SD were found to range between 6.13 and 20° (mean: 10.57±3.76). Deviation angles were 11.7±4.3 for right deviations and 9.9±2.9 for the left deviations, and there was no significant statistical difference (P>0.05) of SD angle degree regarding the side of deviation. These results are compared with studies reported by Saylisoy et al. [3] who found the deviation angles were 6.85±1.47 for right deviations and 7.11±1.63 for the left deviations.

The present study found that the mean width of CP was 5.7±0.8 mm at the right side and 5.6±1.2 mm at the left side (P=0.7), and the mean depth of CP was 5.8±2.05 at the right side and 5.8±1.8 at the left side (P=0.9), whereas the results − according to side of deviation − showed that the mean width of CP was 5.5±0.8 mm at the ipsilateral side and 5.5±1.1 at the contralateral side (P=0.9) and the mean depth of CP was 6.1±1.9 mm at the ipsilateral side and 5.7±1.8 at the contralateral side (P=0.05). By student test, there was no statistically significant difference between the opposite sides.

These results were similar to the studies done by Erdem et al. [4], who found that the mean CP depths were 6.1±2.3 mm on the right side and 6.1±2.2 mm on the left side, and there was no statistically significant difference between the opposite sides. Saylisoy et al. [3] detected that the mean depth of CP was 5.08±1.57 mm on the right side and 5.06±1.59 mm on the left side, and there was no statistically significant difference between the opposite sides. Oakley et al. [15] found the mean depth of CP according to the ‘SD side,’ was 5.9±2.19 mm at the ipsilateral side (deviated side), and at the contralateral side, the mean depth of CP was 6.04±2.1 mm in three groups of the study. There was no statistically significant difference between the opposite sides.

The results in our study were not similar to the studies done by Erdem et al. [4] and Saylisoy et al. [3]. They reported that the mean depth of CP according to ‘SD side’ was 4.9±1.56 mm at the ipsilateral side (deviated side), and 5.22±1.58 mm at the contralateral side. They found that CP depth at the contralateral side was significantly higher than that of the ipsilateral side.

The variability of percentage of Keros classification system was found in the study done by Damar et al. [1], who observed that type I was 18.2% on the right side and 18.2% on left side and type II occurred in 64.2% on the right side and 58.8% on the left side, and type III occurred in 17.6% on the right side and 23% on the left side.

Correlation tests showed a positive correlation between the degree of SD angle and right ethmoid roof width. There was a negative correlation between the degree of SD angle and the left CP width, but Saylisoy et al. [3] reported in their study that as deviation angle increased, ipsilateral and contralateral CP width, as well as right and left CP width increased.

Our study revealed that ipsilateral and contralateral ER width, and also ipsilateral and contralateral ER depth increased together. In other words, right and left ER width and ER depth increased simultaneously. The tests also showed a positive correlation between right and left ethmoid roof width and right and left ethmoid roof depth, as well as contralateral and ipsilateral ethmoid roof (deviated side) width and contralateral and ipsilateral ethmoid roof (deviated side) depth.

Moreover, our study revealed that right and left CP depth increased together and additionally ipsilateral and contralateral CP depth increased together.

These results were, to some extent, like those of Saylisoy et al. [3], except in their study they reported that ipsilateral and contralateral CP width increased together and the CP width of the right and left sides also increased.

The asymmetry of CP and ethmoid roof had been investigated by several authors. Adeel et al. [16] found asymmetry was found in 94.8% of the patients. Souza et al. [17] in a review of 200 CT studies observed asymmetry between the left and right LLCP in 12% of the cases. Dessi et al. [18] analyzed the height of the ethmoid roof in 150 CT studies; asymmetry was observed in 15 (10%) patients. Lebowitz et al. [19] reviewed 200 CT scans and noted asymmetry in 19 cases (9.5%). Alazzawi et al. [20] reported asymmetry in 93% of cases, and Solares et al. [21] and Oakley et al. [15] reported asymmetry of the ethmoid roof in all participants.

High rate of asymmetry of CP and ethmoid roof was noted in our study compared with the aforementioned studies. This is mostly owing to the accurate measurements that are collected by using the computer software, which is able to measure with a precision of 0.01 mm.

The relationship of the ethmoid roof and its CP to other structures has been reviewed by other studies.

Conclusion and recommendations

The findings showed that the severity of deviation did not have an effect on the dimensions of ethmoid roof and CP in terms of depth and width in ipsilateral and contralateral sides and right and left sides except right ethmoid roof width (direct proportion) and the left cribriform width (inverse proportion).

Acknowledgements

This prospective study was carried out at the Otorhinolaryngology and Radiology Departments of Al-Azhar University Hospitals (Al-Hussein and Bab El-She’reya University Hospitals).

The authors thank Otorhinolaryngology and Radiodiagnosis Departments Staff, Faculty of medicine (for Boys), Al Hussein and Bab El-She’reya University Hospitals, Al Azhar University, Cairo.

All authors make substantial contributions to conception and design, acquisition, analysis, and interpretation of data; all authors participates in drafting the paper or revising it critically for important intellectual content; all authors gave final approval of the version to be submitted and any revised version.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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