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Table of Contents
Year : 2022  |  Volume : 71  |  Issue : 4  |  Page : 311-316

The Relationship between Isolated Unilateral Concha Bullosa and Mastoid Air Cell Volumes

1 Department of Otorhinolaryngology, Konya City Hospital, Karatay, Konya, Turkey
2 Department of Radiology, Konya City Hospital, Karatay, Konya, Turkey

Date of Submission14-Sep-2021
Date of Decision04-Jul-2022
Date of Acceptance25-Jul-2022
Date of Web Publication01-Dec-2022

Correspondence Address:
Dr. Fatih Yuksel
Department of Otolaryngology, Konya City Hospital, Akabe, Karatay 42020, Konya
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jasi.jasi_164_21

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Introduction: The purpose of this study was to investigate the relationship between the pneumatization of mastoid air cells (MACs) and isolated unilateral concha bullosa (CB) using computed tomography (CT) scans of the paranasal sinuses (PNS). Material and Methods: A retrospective review of PNS CT scans from 53 patients was performed. Cases with nasal septum angulation >5° were excluded from the study. CT evaluations were made with a 128-slice multislice CT scanner in two projections, axial and coronal. Slice thickness was taken as 1 mm for volumetric analysis. Volume measurements were calculated using the syngo.via software program by selecting the relevant anatomical region and using step-by-step addition and expansion processes. Volumes of the MACs (right and left) and isolated unilateral CB (right and left) were obtained and compared using statistical analysis. Results: The volume of MACs and isolated unilateral CB did not change with age; however, the volumes of male participants were larger than that of women. It was observed that the pneumatization of MACs on the side with isolated unilateral CB was significantly greater than for opposing MACs. Discussion and Conclusion: In our study, it was concluded that the isolated unilateral CB caused a significant increase in the MACs volume on the same side of CB.

Keywords: Computed tomography, concha bullosa, mastoid air cells, volumetric analysis

How to cite this article:
Yuksel F, Kahraman ME, Deniz I. The Relationship between Isolated Unilateral Concha Bullosa and Mastoid Air Cell Volumes. J Anat Soc India 2022;71:311-6

How to cite this URL:
Yuksel F, Kahraman ME, Deniz I. The Relationship between Isolated Unilateral Concha Bullosa and Mastoid Air Cell Volumes. J Anat Soc India [serial online] 2022 [cited 2023 Jan 27];71:311-6. Available from: https://www.jasi.org.in/text.asp?2022/71/4/311/362547

  Introduction Top

Concha bullosa (CB) is the most common anatomical variation of the osteomeatal region.[1],[2] It is usually seen in the middle turbinate, rarely in the superior and inferior turbinates. CB can be unilateral or bilateral, and its incidence ranges from 13% to 53.6%.[3],[4],[5],[6] The mechanism of CB formation remains unclear. CB has been reported to originate from anterior or posterior ethmoid cells extending to the middle turbinate.[7] It is also thought that the imbalance in nasal airflow due to nasal septum deviation (NSD) plays a role in CB formation.[8] However, there are cases with unilateral or bilateral CB without NSD. CB is thought to play a stabilizing role in airflow on both sides of the nasal passage.[9] Unless the CB is large and does not obstruct the nasal airway or sinus ostium, it usually does not cause symptoms or require any treatment.[1]

Another important air structure in skull bones is the mastoid air cells (MACs). Although the function of the MAC is not fully known, it is thought to function as a gas reserve to balance middle ear pressure.[10] Pneumatization of mastoid cells begins at 33 weeks of gestation and continues until puberty.[11] Radiographically, MACs become visible after birth. The mastoid antrum is present at birth. The development of other cells takes place in three stages: the childhood period from birth to 2 years of age, the transitional period between 2 and 5 years, and the adult period.[11],[12],[13] It has been suggested that nasal airflow and positive pressure in the nasopharynx affect the development of mastoid cells through the eustachian tube.[14] It has also been shown that conditions affecting nasal airflow, such as septal deviation, cause changes in nasopharyngeal pressure.[15] There are several theories pointing to the importance of available nasal airflow and normal oxygen pressure for paranasal sinus development.[16],[17] In addition, long-term or recurrent infections in childhood are thought to affect the development of MAC.[18],[19],[20]

Although there are studies investigating the relationship between NSD and CB and between NSD and mastoid pneumatization, we could not find any study in the literature investigating the relationship between CB (isolated concha bullosa) and mastoid pneumatization in patients without NSD. The aim of this study was to evaluate whether the volumes of MACs are affected in patients with isolated concha bullosa (ICB).

  Material and Methods Top

The images of patients who underwent paranasal sinus computed tomography (CT) examination for any reason between August 15, 2020, and February 15, 2021, at Konya City hospital were retrospectively analyzed. Patients under the age of 18, patients with NSD, history of surgery to the sinonasal and mastoid region, maxillofacial and temporal trauma, sinonasal tumor, radiotherapy, granulomatous disease, middle ear infection, and diffuse sinonasal polyposis were excluded from the study. After applying the exclusion criteria, 53 patients (24 (45.3%) female and 29 (54.7%) male) with unilateral CB on paranasal sinus CT were included in the study. Patient consent was not obtained, because this study was conducted from the records. This study complied with the Helsinki Declaration principles. This study was approved by the Necmettin Erbakan University Faculty of Medicine Ethics Committee (Date: February 04, 2021, No: 2021/3171).

Elimination method of patients with septum deviation

Nasal septal deviation evaluated in coronal CT studies was defined as the curvature of the nasal septal contour in any direction. Septal deviation angle was obtained by measuring the angle between a line drawn from the level of crista galli to the level of the maxillary crest and another line drawn from the level of crista galli to the most prominent point of the septal angulation with a protractor. Septal deviation, when the angle was <5, was considered normal.[8] Cases with an angle >5 were evaluated for the presence of septum deviation and were excluded from the study [Figure 1].
Figure 1: The measurement of the angle of septal deviations

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Computed tomography examination method

Images of all patients were reviewed simultaneously by a radiologist and an otolaryngologist. Paranasal CT evaluations were performed with a 128-slice multislice CT scanner in two projections, axial and coronal (Siemens, Germany). CB was considered present, when more than 50% of the vertical height of the middle turbinate became pneumatic (measured from the top of the coronal plane down). The presence of CB on CT scan was defined as unilateral or bilateral. Patients with bilateral CB were excluded from the study.

Slice thickness was taken as 1 mm for volumetric analysis. Volume measurements were calculated using the syngo.via software program by selecting the relevant anatomical region, using step-by-step addition and expansion processes, and finally displayed as colored areas for analysis. The volume of ICB [Figure 2]a and [Figure 2]b and MACs [Figure 3]a and [Figure 3]b was automatically calculated in the three-dimensional reconstruction, 140 kV and 120 mA. The imaging data were stored in a Digital Imaging and Communications in Medicine and then imported to a personal computer running syngo.via software (Germany). When performing reconstruction using a volume-rendering algorithm, the selection of the window thresholds was 1,030 to 300 Hounsfield units.
Figure 2: (a and b) These figures show the program used to measure the volume of the concha bullosa at the workstation. (a: coronal view; b: axial view)

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Figure 3: (a and b) These figures show the program used to measure the volume of mastoid air cells at the workstation. (a: coronal view; b: axial view)

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Statistical analysis

SPSS 26.0 (IBM Corporation, Armonk, New York, United States) program was used in the analysis of the variables. Univariate data were evaluated with the Kolmogorov–Smirnov test and Shapiro–Wilk–Francia test, while the homogeneity of variance was evaluated with the Levene's test. In the comparison of two independent groups according to quantitative data, the independent samples t-test was used together with the bootstrap results, while the Mann–Whitney U test was used together with the Monte Carlo results. Paired samples t-test was used with bootstrap results to compare two replicate measures of dependent quantitative variables with each other. Pearson correlation and Kendall's tau-b tests were used to examine the correlations of the variables with each other. Pearson's Chi-square Monte Carlo Simulation technique was used to compare categorical variables with each other. Quantitative variables were expressed as mean (standard deviation) and median (Percentile 25/Percentile 75) in the tables, while categorical variables were shown as n (%). Variables were analyzed at 95% confidence level, and P < 0.05 was considered statistically significant.

  Results Top

The mean age of the patients was 30.68 ± 10.78 years. Twenty-four (45.3%) patients were female and 29 (54.7%) were male. There was no statistically significant difference in terms of age and gender in patients with right and left ICB (P = 0.112 and P = 0.783, respectively). Right ICB was detected in 24 (45.3%) patients and left ICB in 29 (54.7%) patients. Right ICB volume was 0.87 (0.53/1.28) cm3, and left ICB volume was 0.77 (0.50/1.23) cm3, and there was no statistically significant difference between right and left ICB volumes (P = 0.884). The ipsilateral (right) MAC volume was 14.87 ± 5.67 cm3 in patients with right ICB, ipsilateral (left) MAC volume was 10.29 ± 5.62 cm3 in patients with left ICB, and there was a significant difference between ipsilateral MAC cell volumes in patients (P = 0.007) [Table 1].
Table 1: Comparison of demographic data, isolated concha bullosa, and mastoid air cells volumes by direction of isolated concha bullosa

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Right MAC volumes were 14.87 ± 5.67 cm3 and left MAC volumes were 13.37 ± 5.99 cm3 in patients with right ICB; the difference was statistically significant (P = 0.004). While left MAC volumes were 10.29 ± 5.62 cm3 in left ICB patients, right MAC volumes were 9.19 ± 5.58 cm3; the difference was statistically significant (P = 0.001). It was determined that the MAC volumes on the ipsilateral side of the ICB were larger than the MAC volumes on the contralateral side [Table 2].
Table 2: Comparison of right and left mastoid air cells volumes according to the direction of the isolated concha bullosa

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ICB volumes and right and left MAC volumes were found to be significantly larger in male than in female participants (P values 0.005, 0.026, and 0.022, respectively) [Table 3].
Table 3: Analysis of isolated concha bullosa and mastoid air cells volumes by gender

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  Discussion Top

The size and shape of the paranasal sinuses (PNS) and MAC vary from person to person and can differ between two halves of the body in the same person. This difference is thought to be related to the developmental processes. It has been reported that environmental factors such as trauma and infection, as well as genetic factors, contribute in the difference between individuals.[21],[22],[23] The formation of air spaces within the bone occurs through opportunistic expansion of the epithelium and the formation of bone that counteracts it.[14] Bone formation and factors affecting the epithelium also play a role in the development of air spaces.

The turbinates are important structures arising from the lateral wall of the nasal cavity. The middle turbinate is formed by the medial part of the ethmoid bone. In the 5th and 6th months of the embryonic period, ethmoid air cell groups are formed by the extension of the nasal epithelium to the lateral nasal wall. CB occurs as an extension of the normal pneumatization of ethmoid air cells.[3],[7] Pneumatization of the middle turbinate is mostly mediated by anterior ethmoid cells. Pneumatization through posterior air cells or both have also been reported.[3],[24] Therefore, CB can also be considered a part of the PNS system. CB becomes evident after 7–8 years and continues to develop even after puberty.[25]

MAC differs in size and shape from person to person, is one of the important air structures in the skull bones. MAC development begins with the formation of the mastoid antrum, which can first be recognized at 21–22 weeks of gestation.[11] The mastoid antrum is fully organized at 34 weeks, and there are usually no additional air cells at birth. During the growth and expansion of MACs, mesenchymal tissue is cleared by absorption and/or redistribution.[12],[26] MAC formation continues until puberty with the development of air cells at the petrous apex.[11],[12],[13]

Both airspace systems, consisting of the PNS and the MAC, are formed by resorption of the epithelium in the mastoid bone and PNS. Considering the similar developmental process of both structures, it can be thought that besides genetic factors, CB in the nasal airway may have an effect on MAC. We could not find any study investigating the volumetric relationship of these two structures. We consider this study to be the first.

There are various studies on the relationship between PNS and MAC. MAC pneumatization has been shown to be positively associated with sphenoid sinus pneumatization, but not with maxillary sinuses.[14] Karakas and Kavakli[27] reported that PNS and MAC volumes increase with age, mean volume is lower in women, and there is a positive correlation between right–left and ipsilateral PNS and MACs. Lee et al.[19] reported that there was no interaction in the pneumatization of the PNS and MACs in the pediatric population, and that the growth of both was affected by age. In our study, both mastoid cells and CB volumes were greater in men than in women.

Nasal airflow and positive pressure in the nasopharynx are thought to be factors that affect MAC and PNS pneumatization. The total amount of nasal air space affects nasal airflow, affecting the amount of positive pressure on the mucosa of the nasal cavity and the mastoid cell mucosa through the eustachian nasopharynx.[28] There are studies showing the possible effects of factors affecting nasal airflow, such as NSD, on PNS and MAC, and reporting different findings. Impairment of airflow due to NSD may result in decreased pneumatization of the MAC.[20],[29],[30] Fırat et al.[29] reported that as the degree of NSD increased, the total ethmoid cell volume on the NSD side decreased compared to the opposite side. Karataş et al.[31] showed that moderate septum deviation significantly affects the maxillary sinus volume. Kapusuz Gencer et al.[30] reported that maxillary sinus volume tended to be larger on the opposite side of severe NSD in adults. Lee and Jin[32] showed that the MAC and maxillary sinus volumes on the deviated side were smaller than on the opposite side in a clinical study in children, suggesting that NSD may affect both ventilations. However, there are also studies reporting that NSD does not affect sinus and MAC volumes.[33],[34]

CB is usually asymptomatic and diagnosed incidentally by CT. Swollen or hypertrophic nasal turbinates can cause obstruction of nasal airflow.[35] The ventilated middle turbinate may completely fill the entire space between the septum and the lateral nasal wall, followed by blockage of the osteomeatal complex, predisposing to paranasal sinus infection.[35],[36] Li et al.[9] reported that CB on the undeviated side of patients with NSD makes the airflow more balanced between the bilateral nasal cavities, which may be a compensatory action for nasal physiology from aerodynamic point of view. However, the presence of CB narrows the ipsilateral nasal cavity. Karataş et al.[37] found a moderately positive correlation between CB and maxillary sinus volume, and a low positive correlation between frontal sinus volume. Özkiriş et al.[36] reported that there is a possible relationship between CB and ipsilateral decreased olfactory bulb volume; however, the exact mechanism remains unclear. According to the authors, decreased nasal airflow on the CB side may be attributed to the pathophysiological mechanism of this finding. Septal deviation and unilateral/dominant CB did not affect the asymmetry in the maxillary sinus volumes.[38] However, bilateral CB was associated with larger volumes of maxillary sinuses. In our study, MAC volumes were found to be larger on the side with CB than on the opposite side. This finding suggests that the CB affects MAC volumes positively, unlike NSD. Accordingly, it can be said that the MACs are larger on the side with genetically CB.

The limitations of our study are that the number of patients is small and it is single center. In addition, the patients included in our study were those who underwent paranasal sinus CT for suspected sinonasal disease. Therefore, statistical interpretations of the results of our study are valid only for the symptomatic population.

  Conclusion Top

In our study, it was concluded that the ICB caused a significant increase in the MAC volumes on the side where they were located. According to our results, it was thought that ICB increases MAC aerations.

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Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3]


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