Evaluation of superior semicircular canal bony roof morphology and adjacent pneumatization patterns in children using cone beam computed tomography: a retrospective study

Abstract

Background

This study evaluated the distribution of radiological patterns of the superior semicircular canal (SSC) bony roof and adjacent pneumatization in the pediatric population using cone beam computed tomography (CBCT) and examined their relationship with age and gender.

Materials and methods

CBCT images of a total of 125 patients aged 4–17 years were included in the study. Radiological patterns of the SSC bony roof and adjacent pneumatization were classified as normal, papyraceous, thick, pneumatized, and dehiscent types. Cases showing both pneumatization and dehiscent-like findings were evaluated as a separate subcategory (pneumatized + dehiscent) due to overlapping features. Patients were classified into three groups based on age: 4–8, 9–13, and 14–17. Chi-square test and Fisher’s exact test were used where appropriate, and p < 0.05 was considered statistically significant.

Results

The normal pattern was the most commonly observed radiological pattern on both the right and left sides, followed by the papyraceous and pneumatized patterns. No statistically significant relationship was found between SSC bony roof morphology and age groups, gender, or side. The pneumatized + dehiscent pattern was rare.

Conclusion

In this retrospective CBCT study, the normal SSC bony roof morphology was the most common in pediatric patients, followed by the papyraceous and pneumatized patterns. No statistically significant association was observed between SSC bony roof morphology and age group, gender, or side in this sample. Further prospective studies with clinical and audiovestibular correlation are needed.

Background

The semicircular canals are components of the vestibular apparatus and are anatomically described as the anterior, posterior, and lateral semicircular canals. These approximately orthogonal canals sense angular accelerations and decelerations of the head [1].

In the clinical and radiological literature, particularly in studies on semicircular canal dehiscence, the anterior canal is frequently referred to as the superior semicircular canal (SSC) [2–6]. Therefore, the term SSC was retained throughout this manuscript to maintain consistency with the existing radiological literature.

The SSC is covered by a thin bony layer within the floor of the middle cranial fossa [7]. Thinning or discontinuity of the bony layer covering the SSC may increase the sensitivity of the vestibular system to sound and middle ear pressure changes, leading to clinical findings such as vertigo, abnormal eye movements, auditory symptoms, and autophony [5].

Computed tomography (CT) is a three-dimensional imaging method used to confirm the diagnosis by showing the defect in the bone covering the SSC. However, due to the limitations of CT in distinguishing cases where the bone layer covering the SSC is thin but intact, it may lead to reduced specificity in the diagnosis of superior semicircular canal dehiscence. Nevertheless, multiplanar reformatted images, particularly in planes aligned with the SSC, have been shown to increase diagnostic specificity by reducing false-positive results [8].

Cone-beam computed tomography (CBCT) may provide lower radiation exposure than conventional multidetector CT in dentomaxillofacial imaging, depending on the field of view, device settings, and acquisition protocol [9–12]. CBCT also offers high spatial resolution, isotropic voxels, rapid image acquisition, and multiplanar reconstruction capabilities, allowing detailed evaluation of bony structures such as the temporal bone. However, CBCT has limitations, including lower soft tissue contrast, image noise, artifacts, and possible partial volume effects, particularly when evaluating very thin bony structures such as the SSC roof [9–11].

The majority of studies have focused on adult populations, with limited analyses specific to the pediatric age group [13, 14]. Therefore, evaluating the radiological patterns of the SSC bony roof and adjacent pneumatization in pediatric patients may contribute to a better understanding of radiological variations encountered on CBCT. Clinically, recognizing these appearances may help oral and maxillofacial radiologists interpret incidental SSC findings cautiously and identify cases that may require clinical or otolaryngological correlation.

The aim of this study was to evaluate the distribution of SSC bony roof and adjacent pneumatization patterns in pediatric patients aged 4–17 years using CBCT and to examine their relationship with age and gender.

The null hypothesis was that SSC bony roof and adjacent pneumatization patterns do not differ significantly according to age group or gender in pediatric patients.

Materials and methods

Study design and ethical approval

This retrospective study was conducted with the approval of the Harran University Ethics Committee (Decision No: HRÜ/25.02.58). All stages of the study were conducted in accordance with the principles of the Declaration of Helsinki.

Study population

In this study, CBCT images of patients under the age of 18 who were referred to the Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Harran University, for various clinical indications between 2022 and 2025 were retrospectively evaluated. CBCT images of a total of 125 patients aged 4–17 years with sufficient image quality to allow evaluation of the SSC bony roof and adjacent pneumatization were included in the study.

Patients were divided into three age groups (4–8, 9–13, and 14–17 years) to allow comparison across broad developmental periods within childhood and adolescence. These groups were intended as practical analytical categories rather than strict biological boundaries. The final study population consisted of 125 pediatric patients aged 4–17 years, including 61 females and 64 males.

Patients with temporal bone or vestibular system trauma, a history of temporal bone surgery, congenital inner ear anomalies, or vestibular pathologies were excluded, as were images containing significant motion artifacts or technical artifacts that reduced diagnostic quality.

All CBCT scans included in this study had been acquired previously for clinically justified diagnostic purposes unrelated to this research. No CBCT scan was obtained specifically for the present study. The main clinical indications included impacted or supernumerary tooth evaluation, developmental dental anomalies, maxillofacial pathologies, and preoperative surgical or orthodontic planning.

CBCT imaging protocol

All CBCT images were acquired using a Castellini X-Radius Trio Plus (Imola, Italy) device with exposure parameters of 90 kVp and 16 mAs, a field of view (FOV) of 13 × 16 cm, and an isotropic voxel size of 0.3 mm. The DICOM data were reconstructed with a slice thickness of 0.3 mm using IRYS Viewer 15.1 software.

Evaluation of CBCT images

CBCT images were initially evaluated in the axial plane. Based on the axial images, multiplanar reconstructions were created for detailed evaluation of the SSC. The reconstruction plane approximately parallel to the long axis of the SSC, corresponding to the Pöschl plane, was used as the primary plane for evaluating SSC bony roof morphology.

The Pöschl plane was created at an angle of approximately 45° to the coronal and sagittal planes and parallel to the SSC axis; in this plane, the SSC was observed as a ring-shaped structure. Standard multiplanar views were also reviewed to confirm the continuity and thickness of the bony roof overlying the SSC. The Stenvers plane, reconstructed perpendicular to the Pöschl plane, was used only as a complementary view when needed and was not considered a stand-alone diagnostic plane.

Classification of SSC bony roof morphologies was performed twice by two independent observers after an interval of 14 days. The observers were blinded to their initial evaluations during the second assessment. Inter-observer agreement for the classification of SSC bony roof morphologies was assessed using Cohen’s kappa (κ) coefficient; κ ≥ 0.80 was considered good agreement. The reliability of bone thickness measurements was evaluated using the intraclass correlation coefficient (ICC), which was found to be 0.836 (95% confidence interval = 0.763–0.887), indicating good reliability.

Bone thickness measurement

The minimum thickness of the bone overlying the SSC adjacent to the middle cranial fossa was measured in each temporal bone. The minimum bone thickness was defined as the thinnest point of bone between the outer cortical surface of the SSC and the free surface of the middle cranial fossa in the CBCT sections obtained in the Pöschl plane.

Classification of superior semicircular canal bony roof morphologies

SSC bony roof morphologies were evaluated based on the thickness and integrity of the bony roof and adjacent pneumatization patterns, in accordance with the SSC-related radiological patterns described by Cisneros et al. [15]. Accordingly, SSC bony roof morphologies were classified as normal, papyraceous, thick, pneumatized, and dehiscent. Cases in which pneumatization and dehiscent-like findings were observed together were evaluated as a separate study-specific subcategory, named pneumatized + dehiscent, due to the overlap of morphological features. This approach was preferred because pneumatization and dehiscent-like appearances may overlap radiologically, making differential diagnosis challenging when both findings co-occur.

In this regard, SSC bony roof morphologies were classified according to the following criteria:

• Normal type: The thickness of the bone roof covering the SSC is between 0.6 and 1.7 mm.

• Papyraceous type: A bony covering thinner than 0.5 mm is observed over the SSC.

• Thick type: The SSC roof thickness is greater than 1.8 mm.

• Pneumatized type: A mesh-like appearance is observed on the canal roof due to the presence of supralabyrinthine air cells.

• Dehiscent type: Discontinuity in the bone tissue covering the SSC or the bone roof not being completely visible.

• Pneumatized + dehiscent type: Both pneumatization findings and areas of discontinuity in the bone tissue are observed in the SSC roof.

Representative CBCT images illustrating each SSC bony roof morphology are shown in Fig. 1. The figure demonstrates the normal, papyraceous, thick, pneumatized, dehiscent, and pneumatized + dehiscent patterns used in the classification.

Fig. 1.

Representative CBCT images showing superior semicircular canal (SSC) bony roof morphologies: (a) normal type, (b) papyraceous type, (c) thick type, (d) pneumatized type, (e) dehiscent appearance, and (f) pneumatized + dehiscent appearance

Statistical analysis

Statistical analyses were performed using SPSS version 25 (IBM Corp., Armonk, NY, USA) software. Descriptive statistics were used to calculate numbers and percentages. The relationships between SSC bony roof morphologies and gender, age groups, and side were evaluated using the chi-square test. When the expected cell counts did not meet the assumptions required for the chi-square test and Fisher’s exact test were used, as appropriate. A p-value < 0.05 was considered statistically significant.

Results

The demographic characteristics of the study population and the distribution of SSC bony roof morphologies are presented in Table 1. The mean age of the patients was 12.20 ± 2.90 years.

Table 1.

Distribution of demographic characteristics and SSC bony roof morphologies

	n (%)
Gender	female	61 (48.8)
	male	64 (51.2)
Right SSC bony roof morphologies	pneumatized	16 (12.8)
	normal	68 (54.4)
	dehiscent	9 (7.2)
	papyraceous	22 (17.6)
	thick	7 (5.6)
	pneumatized + dehiscent	3 (2.4)
Left SSC bony roof morphologies	pneumatized	21 (16.8)
	normal	62 (49.6)
	dehiscent	14 (11.2)
	papyraceous	22 (17.6)
	thick	4 (3.2)
	pneumatized + dehiscent	2 (1.6)

When SSC bony roof morphologies were examined on the right side, the highest prevalence was observed in the normal type at 54.4%, followed by the papyraceous type at 17.6% and the pneumatized type at 12.8%. The dehiscent and thick patterns accounted for 7.2% and 5.6%, respectively, while the pneumatized + dehiscent pattern accounted for 2.4%. On the left side, the normal type was the most common at 49.6%, followed by the papyraceous (17.6%), pneumatized (16.8%), dehiscent (11.2%), and thick (3.2%) patterns. The pneumatized + dehiscent pattern accounted for 1.6% (Table 1).

The distribution of SSC bony roof morphologies according to gender is presented in Table 2. No statistically significant association was observed between gender and SSC bony roof morphologies on either side (right: p = 0.625; left: p = 0.089).

Table 2.

Distribution of SSC bony roof morphologies by gender

		Gender Number (%)
		female	male	p
Right SSC bony roof morphologies	pneumatized	11 (8.8)	5 (4.0)	0.625
	normal	33 (26.4)	35 (28.0)
	dehiscent	4 (3.2)	5 (4.0)
	papyraceous	9 (7.2)	13 (10.4)
	thick	3 (2.4)	4 (3.2)
	pneumatized + dehiscent	1 (0.8)	2 (1.6)
Left SSC bony roof morphologies	pneumatized	13 (10.4)	8 (6.4)	0.089
	normal	34 (27.2)	28 (22.4)
	dehiscent	5 (4.0)	9 (7.2)
	papyraceous	9 (7.2)	13 (10.4)
	thick	0 (0)	4 (3.2)
	pneumatized + dehiscent	0 (0)	2 (1.6)

Values are given as n (% of total sample)

Chi-square test and Fisher’s exact test were used where appropriate

Statistical significance was set at p < 0.05

The distribution of SSC bony roof morphologies according to age groups is presented in Table 3. No statistically significant association was observed between age group and SSC bony roof morphologies on either side (right: p = 0.314; left: p = 0.745).

Table 3.

Distribution of SSC bony roof morphologies by age group

		Age Group Number (%)
		4–8	9–13	14–17	p
Right SSC bony roof morphologies	pneumatized	1 (0.8)	12 (9.6)	3 (2.4)	0.314
	normal	8 (6.4)	29 (23.2)	31 (24.8)
	dehiscent	0 (0)	5 (4.0)	4 (3.2)
	papyraceous	2 (1.6)	14 (11.2)	6 (4.8)
	thick	2 (1.6)	2 (1.6)	3 (2.4)
	pneumatized + dehiscent	0 (0)	2 (1.6)	1 (0.8)
Left SSC bony roof morphologies	pneumatized	1 (0.8)	12 (9.6)	8 (6.4)	0.745
	normal	7 (5.6)	30 (24.0)	25 (20.0)
	dehiscent	1 (0.8)	7 (5.6)	6 (4.8)
	papyraceous	2 (1.6)	13 (10.4)	7 (5.6)
	thick	2 (1.6)	1 (0.8)	1 (0.8)
	pneumatized + dehiscent	0 (0)	1 (0.8)	1 (0.8)

Values are given as n (% of total sample)

Chi-square test and Fisher’s exact test were used where appropriate

Statistical significance was set at p < 0.05

Discussion

This study contributes to the literature by evaluating SSC bony roof morphologies in the pediatric age group using CBCT. Most existing studies have focused on the adult population, and data on the distribution of SSC bony roof morphologies in children and adolescents are relatively limited. It has previously been reported that thin bone or dehiscent-like appearances detected in radiological examinations of pediatric patients may reflect the range of radiological appearances observed in pediatric imaging and should be interpreted in the clinical context [16]. Although CBCT may allow detailed evaluation of different radiological patterns of the SSC bony roof structure, comprehensive evaluations specific to the pediatric age group appear to be limited [6]. On the other hand, it is emphasized that the prevalence of radiological dehiscence reported in high-resolution CT studies does not always correspond with histopathological data, and that this situation may carry the risk of overdiagnosis [17].

In this regard, the added value of the present study lies in its focus on a pediatric population, in which data on SSC bony roof and adjacent pneumatization patterns are limited compared with adult populations. Rather than aiming to establish a clinical diagnosis of SSC dehiscence, this study provides descriptive reference data on the distribution of SSC bony roof morphologies in children and adolescents using CBCT. These findings may contribute to a better understanding of the range of SSC bony roof morphologies in pediatric CBCT images and may serve as a basis for future studies incorporating clinical, audiovestibular, and higher-resolution imaging correlations.

The results of this study show that SSC bony roof morphologies were most frequently observed as normal type on both sides, followed by the papyraceous and pneumatized types. This observed distribution is generally consistent with the results reported in previous CBCT studies that used classifications based on the thickness of the SSC bone structure. The predominance of normal and papyraceous types suggests that these appearances fall within the spectrum of SSC bony roof morphologies previously described in CBCT-based evaluations [18]. Cisneros et al. described five radiological patterns of the SSC bony roof, providing a useful framework for evaluating these patterns [15]. In this context, our findings suggest that SSC bony roof variations in the pediatric population represent a range of radiological patterns described in the literature.

The distinction between the papyraceous pattern and true dehiscence is critical for accurately assessing SSC bony roof morphologies, particularly in the pediatric population. Classifying cases in which pneumatization and dehiscent findings coexist as a separate pattern acknowledges that these findings may overlap radiologically in the pediatric population and that evaluating them separately may increase the risk of misclassification. In high-resolution CT studies, it has been reported that evaluation based solely on axial sections may increase false-positive dehiscence rates; in contrast, reconstructions in the Pöschl and Stenvers planes can more reliably reveal the continuity of the SSC roof [19]. However, even when these advanced reconstruction techniques are used, the very thin bone layer may appear discontinuous or absent due to the spatial resolution limitations of imaging systems, and this situation may be interpreted radiologically as dehiscence. Studies conducted on normal and asymptomatic individuals have shown that even at the thinnest point of the SSC roof, a certain bone thickness is preserved in most cases and that this thickness does not show a significant relationship with age or gender [14]. In light of these data, papyraceous appearances should be interpreted cautiously, particularly in pediatric cases without accompanying clinical or audiovestibular data. Therefore, papyraceous and dehiscent radiological findings should not be interpreted in isolation and should be evaluated together with clinical data.

Our data reveals no significant difference in SSC bony roof morphologies between the right and left sides. This finding suggests that, within the present sample, SSC bony roof morphologies showed a broadly similar distribution between the right and left sides. However, the absence of a statistically significant difference should not be interpreted as definitive evidence of biological symmetry. Studies evaluating the temporal bones histopathologically have reported that the bone covering the SSC does not show a consistent distribution indicating a clear lateral dominance between the right and left sides, and that dehiscence may exhibit a bilateral or variable pattern [20]. Similarly, studies that considered both radiological and clinical data have stated that there is no consistent evidence supporting the idea that SSC dehiscent or thin-bone patterns are more common in the right or left temporal bone [21]. These findings suggest that side-based differences may mostly stem from variability related to sample characteristics or imaging techniques. Within this framework, it was concluded that the observed right–left distribution of SSC bony roof morphologies was consistent with the literature and that interpretations based solely on side dominance may not be clinically decisive in evaluating SSC bony roof morphologies in the pediatric population. Therefore, side-related interpretations should be made cautiously and should not be considered clinically decisive without clinical correlation.

When the gender variable was taken into account, no significant difference was found between female and male patients in terms of the SSC bony roof morphologies. Studies that histologically examined the temporal bones also reported no significant differences in bone thickness and the presence of dehiscence on the SSC between female and male individuals; this finding may support the view that SSC bony roof morphologies are not strongly influenced by gender, although this interpretation should be made cautiously [14]. Similarly, radiological studies emphasize that SSC dehiscence or thin bone patterns do not differ in prevalence between genders and that gender alone is not a determining factor [13]. In particular, the fact that hormonal or age-related secondary bone changes are not yet apparent in pediatric and young patient groups may explain why gender-related differences have not been detected in this anatomical region. In this context, it is thought that the results obtained are consistent with the literature and that gender-based interpretations should be made cautiously, particularly because clinical correlation was not available in the present study.

Our study did not reveal a significant relationship between age groups and SSC bony roof morphologies. This finding suggests that SSC bony roof morphologies in the 4–17-year age range did not show a clear age-related distribution in the present sample. The results of previous studies evaluating the relationship between SSC bone thickness and age are heterogeneous; while some series reported a tendency for thinning of the SSC bone cover with age [22], others discussed the possible effects of aging and physiological periods such as menopause [23]. However, most of these studies were conducted in adult populations, and caution is required when directly generalizing adult-based findings to pediatric patients. To the best of our knowledge, no pediatric CBCT study has evaluated SSC bony roof morphologies; therefore, direct comparison with previous studies was not possible. In addition, because the age groups in the present study represent broad developmental categories rather than strict biological stages, and because subgroup sizes were limited, the age-related findings should be interpreted cautiously.

When interpreting SSC bony roof morphologies in the pediatric population, it is essential to distinguish between the intrinsic structure of the otic capsule and the surrounding temporal bone environment. The otic capsule undergoes early ossification during fetal development and remains largely stable throughout life, with minimal remodeling compared to other skeletal structures [24]. This supports the assumption that the intrinsic thickness of the otic capsule remains relatively stable after development, rather than undergoing substantial age-related remodeling. Therefore, major postnatal remodeling of the intrinsic otic capsule is generally considered limited [25].

In contrast, the radiological appearance of the bone overlying the SSC may be influenced by the surrounding temporal bone anatomy, particularly by adjacent pneumatization patterns around the superior semicircular canal [26]. The variability and distribution of temporal bone air cell systems may complicate the radiological assessment of the SSC roof. In particular, supralabyrinthine or overlying air cells should be distinguished from true bony defects, as their presence has been associated with an intact SSC roof and may support classification of the canal as nondehiscent despite an apparently thin bony covering [26–28]. Furthermore, imaging-related factors, including limited spatial resolution and partial volume effects, may contribute to the misinterpretation of very thin but intact bone overlying the SSC as dehiscent on CT-based imaging [28, 29]. This distinction is especially important in pediatric populations, where ongoing craniofacial development and variable pneumatization patterns may further complicate radiological assessment. Therefore, radiological findings suggestive of papyraceous or dehiscent-like patterns should be interpreted cautiously and should not be directly equated with pathological dehiscence in the absence of clinical correlation.

From a broader anatomical perspective, although this relationship was not directly evaluated in the present study, previous anatomical literature suggests that cranial and brain asymmetry patterns, including occipital petalia, may be associated with skull base asymmetry, including variations in structures related to the petrous part of the temporal bone [30]. Similarly, long-term biomechanical factors, including subtle brain pulsation forces, have been proposed as potential contributors to bone remodeling in adjacent cranial structures [31]. However, the available evidence remains limited, and these potential mechanisms were not directly evaluated in the present study.

Taken together, these findings suggest that SSC bony roof morphologies likely reflect a combination of stable intrinsic otic capsule anatomy, variable surrounding bone pneumatization, and imaging-related factors. Accordingly, the absence of statistically significant differences across age groups or gender in the present study should be interpreted with caution, as it does not necessarily indicate true biological invariance but may also reflect sample size limitations and methodological constraints.

Limitations

This study has several limitations. First, due to its retrospective design, no direct correlation was established with clinical symptoms, audiological findings, or vestibular test results; therefore, the clinical counterpart of the radiological findings could not be evaluated. Second, although CBCT provides high spatial resolution, the reliable distinction between papyraceous bone and true dehiscence may still be affected by partial volume effects and imaging-related limitations when evaluating very thin bony structures. In addition, the CBCT findings were not validated against high-resolution CT, histopathological data, or surgical findings; therefore, dehiscent-like appearances should be interpreted as radiological findings rather than definitive diagnostic entities. Third, the study was based on archived CBCT scans obtained for different clinical indications, which may have introduced selection bias and may limit generalizability to the general pediatric population. Finally, the study was single-center and included a broad pediatric age range of 4–17 years. Although subgroup analyses were performed, the age groups were broad and subgroup sizes were limited, which may have reduced the ability to detect subtle age-related differences. Future prospective studies using thinner isotropic imaging protocols and incorporating clinical and audiovestibular correlation are needed.

Conclusion

In this retrospective CBCT study, the normal SSC bony roof morphology was the most common in pediatric patients, followed by the papyraceous and pneumatized patterns. No statistically significant association was observed between SSC bony roof morphologies and age group, gender, or side in this sample. Further prospective studies with clinical and audiovestibular correlation are needed.

Abbreviations

SSC

Superior semicircular canal

CBCT

Cone-beam computed tomography

CT

Computed tomography

SPSS

Statistical package for the social sciences

DICOM

Digital imaging and communications in medicine

ICC

Intraclass correlation coefficient

Authors’ contributions

Conceptualization: Ş.A., M.E.D., S.D.Y.; Methodology: Ş.A., M.E.D., S.D.Y.; Data collection: Ş.A., M.E.D.; Image evaluation and analysis: Ş.A., M.E.D.; Statistical analysis: Ş.A., M.E.D.; Writing – original draft: Ş.A., S.E., M.E.D.; Writing – review & editing: Ş.A., M.E.D.; Supervision: M.E.D.

Funding

No funding was received for conducting this study.

Data availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Ethical approval was obtained from the Ethics Committee of Harran University (approval number: HRÜ/25.02.58). The study was conducted in accordance with the Declaration of Helsinki. Due to the retrospective design of the study and the use of anonymized archival CBCT images, the requirement for study-specific informed consent was waived by the ethics committee.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.