Accepted Manuscript

Evaluation of the superior semicircular canal morphology using cone-beam computedtomography: A possible correlation for TMJ symptoms

Hakan Kurt, Kaan Orhan, Secil Aksoy, Sebnem Kursun, Nihat Akbulut, BurakBilecenoglu

PII: S2212-4403(14)00014-5

DOI: 10.1016/j.oooo.2014.01.011

Reference: OOOO 823

To appear in: Oral Surgery, Oral Medicine, Oral Pathology and OralRadiology

Received Date: 27 September 2013

Revised Date: 20 December 2013

Accepted Date: 5 January 2014

Please cite this article as: Kurt H, Orhan K, Aksoy S, Kursun S, Akbulut N, Bilecenoglu B, Evaluationof the superior semicircular canal morphology using cone-beam computed tomography: A possiblecorrelation for TMJ symptoms, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2014),doi: 10.1016/j.oooo.2014.01.011.

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Evaluation of the superior semicircular canal morphology using cone-beam computed

tomography: A possible correlation for TMJ symptoms

Hakan Kurta*, Kaan Orhana,b, Secil Aksoyb, Sebnem Kursuna, Nihat Akbulutc,

Burak Bilecenoglud

a Ankara University, Faculty of Dentistry, Department of Dentomaxillofacial Radiology, Besevler,

Ankara, Turkey

b Near East University, Faculty of Dentistry, Department of Dentomaxillofacial Radiology, Mersin 10,

Turkey

cGaziosmanpaşa University, Faculty of Dentistry, Oral and Maxillofacial Surgery

Department, Tokat, Turkey.

d Ankara University, Faculty of Dentistry, Department of Anatomy, Besevler, Ankara, Turkey

Word Count-Abstract: 150

Complete manuscript word count (to include body text and figure legends):5426

Number of references: 42

Number of figures/tables: 1 Table, 6 figures

*Corresponding author: Dr. Hakan Kurt

Ankara University, Faculty of Dentistry,

DentoMaxillofacial Radiology Department, 06500 Ankara, Turkey.

Tel:+905334811997

e-mail: mhakankurt@yahoo.com

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Evaluation of the superior semicircular canal morphology using cone-beam computed

tomography: A possible correlation for TMJ symptoms

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Abstract

Objective. To assess the superior semicircular canal (SSCC) morphology and to determine

whether the SSCD correlate with the temporomandibular joint (TMJ) symptoms.

Study Design. Clinical data and CBCT of 175 patients were retrospectively examined by two

observers. The distribution and thickness measurements of the different types of bone cover

of the SSCC were performed.

Results: Five radiological SSCC pattern was identified from CBCT data. 147 cases (42 %),

defined as normal (0.6 -1.7 mm thickness), 62 cases (17.71%) as papyraceous-pattern (<0.5

mm), 77 cases (22%) showed thick pattern (>1.8 mm), and pneumatized-pattern in 42 cases

(12 %). Observer 1 and 2 diagnosed SSCD in 22 of 350 (6.28%) temporal bones individually

and had no discordances between the two reviews. All patients with SSCD had identified as

having TMJ sign and symptoms (p<0.05).

Conclusion: Maxillofacial Radiologists should be aware about these structures which can be

helpful for the interpretation of CBCTs.

Key words: Superior semicircular canal, Dehiscence, Cone beam computed tomography

temporomandibular joint

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Introduction

The semicircular canals as defines as three canals in the bony labyrinth of inner ear that are

continuous with the vestibule, namely superior, posterior and lateral semicircular canals1.

The superior semicircular canal (SSCC) is a part of the vestibular system and detects rotation

of the head around a rostral-caudal (anterior-posterior) axis. A portion of the superior

semicircular canal is closely related to arcuate eminence on the anterior surface of the petrous

bone which is located anterolaterally at an angle of approximately 45 degrees to mid sagittal

plane transversely to the long axis of the petrous bone, on the anterior surface of which its

arch forms a round projection 1-2.

Malformation of the lateral canal is most common in inner ear anomalies while

superior and posterior semicircular canal without lateral canal involvement is unusual3.

However, the superior semicircular canal has been a specific topic of study since 1998, when

Minor described a syndrome, associated with the dehiscence of its roof 3-5.

Superior semicircular canal dehiscence (SSCD) syndrome caused by the lack of bone

overlying the superior semicircular canal. Vertigo following loud noises (Tullio phenomenon)

and autophony, oscillopsia, disequilibrium due to sounds, changes in middle ear pressure, or

changes in intracranial pressure were observed in these patients. A postmortem survey of

more than 1,000 temporal bones reported the prevalence of superior SCD syndrome in adults

at 0.7%6-8. Besides, a case of otogenic brain abscess was also reported which was derived

from an infectious labyrinthitis that spread intracranially through a dehiscence of the superior

semicircular canal9. The etiology of SCD syndrome is unknown. Rarely, causative insults can

be attributed to direct head injury. More frequently, dehiscences are hypothesized to result

from pressure from overlying tissues or from pulsations of cerebrospinal fluid, arachnoid

granulations, the sigmoid or superior petrosal sinuses. Alternatively, SCDs may result from

anomalies in bone deposition during childhood and adolescence1-2,7-8.

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The imaging study of semicircular canals began in 1943 with Chaussé. Throughout the

following decades, new projections were described such as those of Schüller II (petrous bones

in the orbits), and Towne (semi-axial), Stenvers (occipitozygomatic) and others6 The most

commonly accepted imaging study for diagnosis of SCD syndrome is high-resolution

computed tomography (CT) of the temporal bone10-15. Accuracy of CT is paramount because

the finding of SSCD on CT in a patient with debilitating symptoms may lead to a craniotomy

or other surgical approach for repair. However, several studies indicated that that current CT

imaging overestimates the prevalence of SSCD and also differ in the frequency of dehiscence,

with higher prevalence values in radiologic studies16-18. Moreover, it was stated that it is still

difficult to analyze complex middle ear anatomy when using CT imaging only19. CT has been

of great value in evaluating the condition of the middle ear cavity and labyrinth but in spite of

the use of very thin adjacent slices, CT is not yet a perfect technique. Recently, Sequeira et

al.16 concluded in their study that medical CT cannot be used as the exclusive gold standard

for SSCD and that, particularly for small dehiscences on CT.

The use of cone-beam computed tomography (CBCT) was first reported by Mozzo et

al.20 and has been proposed in the last decade for maxillofacial imaging21-22. CBCT offers the

distinct advantage of a lower radiation dose, thinner slices than MDCT and the possibility of

importing and exporting individualized, overlap-free reconstructions22-24. CBCT provides

increased spatial resolution as compared to CT18. Moreover, these possibilities and increasing

access to CBCT imaging esp. for surgeons are enabling the movement for this modality22.

Numerous studies of detection of this anatomical variation, using conventional CT,

cinical and cadaver studies have been published7-8,10-11,13-16,25-31. However, “to the best of our

knowledge” only two studies have been conducted on CBCT imaging18,32, but to our

knowledge, no attempt has been made to study a possible connection with SSCD and

temporomandibular joint (TMJ) symptoms. Hence, it was considered worthwhile to assess the

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superior semicircular canal SSCC morphology and presence of dehiscence of this canal using

CBCT and to determine whether the SSCD correlate with the TMJ symptoms.

Material and Methods

Data from CBCT examinations of 350 sites in 175 patients (100 females/50 males) who had

been referred to outpatient clinic during a 5-year period were analyzed retrospectively. The

overall mean age was 36.4 years [range: 20–84 years, standard deviation (SD): 15.5 years].

The mean age of the male patients was 38.4 (SD, 14.1; n = 75) years (range, 20–73 years),

while the mean age of the female patients was 34.6 (SD, 14.4; n = 100) years (range, 20–84

years). The patients were also classified according to age as decades. The age distribution of

the study population is presented in Figure 1.

Patients with evidence of bone disease (especially osteoporosis), relevant drug

consumption, skeletal asymmetries, congenital disorders, anamnesis of surgical procedures in

the TMJ, and pathological disorders of the maxilla and mandible as well as syndromic

patients were excluded from the study. The study protocol was carried out according to the

principles described in the Declaration of Helsinki, including all amendments and revisions.

Only the investigators had access to the collected data. The institutional review board of the

faculty reviewed and approved informed consent forms. There was no preference for gender

regarding sample choice. Only high-quality scans were included. Low-quality images, such as

those containing scattering or insufficient accuracy of bony borders, were excluded.

Imaging using CBCT

CBCT scans (NewTom 3G; Quantitative Radiology s.r.l., Verona, Italy) used 9 inch field of

view (FOV) to include the craniofacial anatomy. Radiographic parameters (kV, mA) were

determined automatically from scout views by the NewTom 3G. Depending on the size of the

patient and the extent of beam attenuation, exposure varied up to 40%. The raw data were

obtained with the voxel size of 0.25 mm3 voxel size (isotropic voxels) for given specific FOV

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and also with 0.4mm axial slice thickness, 0.25-0.36mm axial pitch. For each ear, reformatted

images were created in the coronal plane. All reformations had a section thickness of 1 mm

and a spacing of 1 mm and were constructed using average voxel density. All constructions

and measurements were performed on a 21.3-inch flat-panel color-active matrix TFT medical

display (NEC MultiSync MD215MG, Munchen, Germany) with a resolution of 2048 × 2560

at 75 Hz and 0.17-mm dot pitch operated at 11.9 bits.

Image evaluation

The CBCT images were obtained first on the axial plane and reformatted images in the

plane of Pöschl and in the plane of Stenver from the axial images. The Pöschl plane is

approximately at a 45° angle to coronal and sagittal planes and specifically aligned parallel to

the superior semicircular canal. The superior semicircular canal is viewed as a whole ring in

this plane. The Stenver plane is perpendicular to the Pöschl plane. It is also approximately at a

45° angle to coronal and sagittal planes and displays a clear image of the roof of the superior

semicircular canal (Figure 2-3).

Each of the superior semicircular canals was evaluated in the plane of Pöschl and

Stenver reformatted images together with axial images. The SSCC was classified according to

Cisneros et al.’s6 study as;

Normal pattern (Figure 4a–b); SSCC thickness measures between 0.6 and 1.7 mm;

Papyraceous pattern (Figure 4c) characterized by presenting a fine thin cover, whose

thickness was <0.5 mm, Thick pattern (Figure 4d) those canals with a thickness of >1.8 mm);

Pneumatized pattern (Figure 4e) this is the pattern where the roof of the canal is occupied by

multiple supralabyrinthine cells, making it look like a woven structure. The morphometric

study determined a thickness of more than 2.5 mm in all the cases; Dehiscent pattern (Figure

4f) characterized by presenting a continuum in the bone cover of the canal. Moreover SSCC

length was measured in the Pöschl plane.

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The clinic files of all patients was retrieved from our department’s database to

document clinical symptoms. The TMJ symptoms (if exist) of these patients were carefully

noted according to their clinical evaluation and anamnesis files. The age and sex for all

patients were also recorded. Besides, TMJ bone structures were also investigated in CBCT

images and classified by the presence of one or more of the following: deformities of the

articular surfaces associated with flattening, surface irregularities, erosion, and osteophyte

formation.

All SSCC classifications were made by the reviewers individually without knowing

the clinical conditions of the patients. Any instance of an intraobserver discrepancy between

the readings was subjected to a post hoc consensus review with both observers to determine

the cause of the discrepancy and a final classification was made by the consensus of the

observers. In the meantime, all measurements were also made twice by the same observers,

and the mean values of all measurements were included in the statistical analysis.

The observers also performed the study twice with an interval of 2 weeks to detect

intra-observer variability. Moreover, before starting the radiographic examination in the

study, the examiners were calibrated to recognize as well as to identify the middle ear

anatomy. For such purpose, a different 50 CBCT, other than this study were used. The

examiners only examined the CBCTs and were blinded to any other patient data in the

radiographic examination procedure.

Examiner reliability and statistical analysis

Statistical analyses were carried out using the SPSS 17.0.1 software (SPSS, Chicago,

IL, USA). Intra- and inter-examiner validation measures were conducted. To assess intra-

observer reliability, the Wilcoxon matched-pairs signed rank test was used for repeat

measurements. The inter-observer reliability were determined by the intraclass correlation

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coefficient (ICC) and the coefficient of variation (CV) [CV=(standard

deviation/mean)x100%]. Values for the ICC range from 0 to 1. ICC values greater than 0.75

show good reliability, and the low CV demonstrates the precision error as an indicator for

reproducibility33 . Differences in age, sex, occurrence, and location were evaluated using chi-

square and paired t-test and measurements were evaluated using one way ANOVA tests.

Differences were considered significant when P < 0.05.

Results

Intra-observer consistency

Repeated CBCT evaluation and measurements indicated no significant intra-observer

difference for both observers (p > 0.05). Overall intra-observer consistency for observer 1 was

92.4% between two examinations, 94.4% the detection of SSCC and 92.1% TMJ morphology

and 100% for the detection of SSCD cases while the consistency for observer 2 was found

89.8% between two examinations, 90.2% the detection of SSCC and 90.2% TMJ morphology

and 100% for the detection of SSCD cases, respectively. All measurements were found to be

highly reproducible for both observers and no significant difference was obtained from two

measurements of the observers (p > 0.05).

Inter-observer consistency

There was no discordances in detecting the SSCD between the two reviews (ICC 1.0). The

intra-observer as well as inter-observer detection of SSCD were 100%. The ICCs for the

measurements between Observer 1 and Observer 2 which ranged from 0.972 (CV-1.98%).

There was a high inter- observer agreement, while a high ICC and low CV demonstrated that

the procedure was standardized between the evaluations and measurements of the observers.

No statistical differences were found among observers evaluations and measurements

(p<0.05). The observers were detected SSCD individually and also examined and made the

measurements individually.

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Five radiological SSCC pattern was identified following Cisneros et al.’s study from

CBCT data. Five radiological SSCC pattern was identified from CBCT data. 147 cases (42

%), defined as normal (0.6 -1.7 mm thickness), 62 cases (17.71%) as papyraceous pattern

(<0.5 mm), 77 cases (22%) showed thick pattern (>1.8 mm), and pneumatized pattern in 42

cases (12 %), which is characterized by having supralabyerinthine cells. Observer 1 and 2

diagnosed SSCD without discordances between the two reviews in 22 of 350 temporal bones

individually, for a radiologic prevalence of 6.28 % in 20 patients (12 females/8 males). Nine

cases were in the right and nine in the left superior semicircular canal, while two cases were

bilateral (Figure 5).

The statistical tests were showed no statistical significant differences with respect to

gender, localization, and age (p>0.05) (Figure 6). SSCD length varied between 1.2 and 5.8

mm (mean 3.29 mm). No significant difference for defect length was found for left (mean 3.4

mm) and right (mean 3.1 mm) sides (p>0.05). Five of the defects were smaller than 2 mm, 9

were between 2 and 4mm and 8 were larger than 4mm.

Following this, the clinical files of these patients were retrieved and the TMJ

symptoms of patients were noted for further correlation. From patients’ records, it was

retrieved that in total there were 28 patients with TMJ symptoms. Of all these patients, all

patients (n=20) with SSCD had identified as having TMJ sign and symptoms (p>0.05). The

SSCC of the rest eight patients were identified as; normal (n=5) and pneumatized pattern

(n=3) bilaterally. Although no difference was found among age, sex and location (p>0.05), all

patients (n=20) with SSCD had identified as having TMJ sign and symptoms with statistical

significant (p<0.05) (Table 1). The most common symptoms in dehiscent patients were

scattered pain in TMJ and ear area following tinnitus. Three patients were reported

disequilibrium due to sounds. Eight patients were reported to have clicking while 2 patients

showed crepitus. In total 9 patients had restriction of motion.

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Moreover, CBCT images showed flattening of the TMJ condyle in seven patients

while 8 patients showed surface irregularities and 2 patients showed osteophyte formation.

(Table 1). No significant difference was found between dehiscent patients and other SSCC

types regarding TMJ CBCT findings (p<0.05).

Discussion

Superior semicircular canal dehiscence (SSCD) is first described as a phenomenon in 1998 by

Minor et al.4 that results from thinning or absence of bone overlying the superior semicircular

canal. Cisneros et al.6 classified SSCD in terms of thinning of bone overlying superior

semicircular canal in their radiological case series as normal (amount of overlying bone

thickness ranged 0,6mm to 1.7mm), fine pattern (bone thickness<0.5mm), thick pattern

(thickness >1.8mm), pneumatised pattern that has the roof of the canal is occupied by

multiple supralabyrinthine cells, making it look like a woven structure (bone

thickness>2.5mm) and dehiscent pattern characterized by presenting a continuum in the bone

cover of the canal (bone thickness=0mm).

According to literature survey, few studies was found for the cadavers. Mondina et

al.15 evaluated 37 cadaver temporal bones and found out a prevalence of 8% for SSCD with

1.3 to 2.6 mm lenght in Pölsch plane. Dalchow et al.32 investigated Egyptian mummies with

CBCT imaging and found one SSCD in 20 temporal bones. Sequeira et al.16’investigated the

potential of CT for detecting the SSCD in cadaver patients using Micro-CT and compared

with those of CT.

Most of the studies were conducted on CT imaging. Cisneros et al.6 reported in total

163 temporal bones of their cases including normal pattern with 121 cases (74.2%), fine

pattern with 23 cases (14.1%), thick pattern with 11 cases (6.74%), pneumatized pattern with

five cases (3.06%) and finally dehiscent pattern with three cases (1.84 %). In the present

study, 147 cases (42 %), defined as normal (0.6 -1.7 mm thickness), 62 cases (17.71%) as

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papyraceous pattern (<0.5 mm), 77 cases (22%) showed thick pattern (>1.8 mm), and

pneumatized pattern in 42 cases (12 %), which is characterized by having supralabyerinthine

cells. A higher incidence of SSCD pattern as found than Cisneros et al.6’s study ( 1.84 vs

6.28%). Hagiwara et al.12 found in young individuals that the thinning of bone overlying the

semicircular canals was much more than adults. In contrary to these findings, present results

showed that there was no difference in terms of bone thinning overlying the semicircular

canals. Allen et al.34 investigated the patients eith middle fossa craniotomy for repair of

spontaneous CSF otorrhea and detected a dehiscence of the superior canal was observed in

15.2% of ears which is higher than ours. This difference can be due to patient sample.

Crovetto et al.8 also evaluated 604 ears and 160 cadaver temporal bones have been

investigated by means of CT scan and direct observation, respectively and found a prevalence

of 3.6% SSCD. Thabet et al35 stated that CT can be also used for detection of SSCD but

preferably larger than 2 mm length. Loke and Goh36 investigated 481 scans and found 10

cases of SSCD with CT imaging. According to literature survey, our radiological findings

showed that the prevalence of dehiscent pattern (6.74%) is compatible with Mondina et al.15

(8%), Nadgir et al.37 (7%), but it is not compatible with Ceylan et al.17 (12%), Crovetto et al.38

(3.6%) and Loke and Goh36 (2%). This difference can be based on regarding the studied

population.

In contrast to the prevalence, our findings regarding the size measurements of

dehiscence (ranged 1.2 to 5.8 mm) are similar to Sequeira et al.16’s (ranged 1.6 to 5.4 mm) ,

Ceylan et al.17’s (ranged 1 to 6.5 mm) and findings of dehiscence size and Hirnoven et al31.

(4.3 for unilateral and 4.5 mm for bilateral). Also no significant difference was detected for

occurrence and defect length of dehiscence between right and left side of the individuals.

Some authors reported that the size of dehiscence is highly important (especially with

dehiscence >3mm) in terms of the symptoms of this phenomenon as conductive hearing loss,

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vestibular symptoms e.g.39-40. We observed 17 dehiscence cases with the size of >2mm that

consisted almost most of the cases.

Patients with superior semicircular canal dehiscence syndrome may have some

symptoms or causes such as vertigo and/or nystagmus, oscillopsia, (Tullio phenomenon),8, 15-

17, 27, 36-40, autophony, disequilibrium due to loud noise, fistula symptoms,27 conductive

hearing loss, tinnitus, vestibular symptoms,8, 15-17, 27, 36-40. Present study interestingly reported

that all of the SSCD patients had TMJ symptoms with statistically significant results (p<0.05).

These results also differs this study from other SSCD works. The most common symptom in

dehiscent patients were scattered pain in TMJ and ear area following tinnitus. Three patients

were also reported disequilibrium due to loud sounds. The other remain patient had clicking,

crepitus, restriction of motion and shape irregularities of TMJ condyle in the joint region.

Sencimen et al.41 published a study about TMJ and ear relation about anatomical and

functional aspects of the discomallear ligament (DML), malleomandibular ligament (MML)

and sphenomandibular ligament (SML). They reported that extreme stretching of the condyle

in conjunction with the ligaments between the ossicles of the inner ear and TMJ may be the

reason for unexplained otological and TMJ disorders.

The etiology of SSCD is unclear and it is also controversial issue in head and neck region.

Some studies 12, 37 stated that the congenital, developmental, and genetic factors as the first

condition leading to SCCD, but the second possibilities of occurring this entity may be a

sudden change in middle ear pressure, or pulsatile high mid cranial pressure, pulsations of the

superior petrosal sinuses or sigmoid, arachnoid granulations (head trauma, direct injury of

SSC, etc.) during adulthood especially in obese patients. Alternatively, SSCD may result from

disturbance in bone deposition during development of individuals. 1-2,7-8,12,37 In these

developmental or genetic stages, TMJ and all of ear compartments interact in with each

other’s structure as the occurring of DML or MML in between joint and ear region. So, ear

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and TMJ related pain or other symptoms of these areas may be the causes of these etiologic

or attached or connected ligaments’ factors presented in this and/or Sencimen et al.41’s

studies. All of SSCD symptoms have clearly been defined in the literature, but current study

results showed that when clinicians detect any symptom of SSCD, the TMJ symptoms should

be taken into account or investigated.

The imaging study of semicircular canals began in 1943 with Chaussé. To date, the most

commonly accepted imaging study in the assessment of SCD syndrome is high-resolution

computed tomography (HR-CT) of the temporal bone10-15. Accuracy of CT is paramount

because the finding of SSCD on CT in a patient with debilitating symptoms may lead to a

craniotomy or other surgical approach for repair. However, several studies indicated that

current CT imaging overestimates the prevalence of SSCD and also differ in the frequency of

dehiscence, with higher prevalence values in radiologic studies15-18. Moreover, it was stated

that it is still difficult to analyze complex middle ear anatomy when using CT imaging

only18,19. CT has been of great value in evaluating the condition of the middle ear cavity and

labyrinth but in spite of the use of very thin adjacent slices, CT is not yet a perfect technique.

Recently, Sequeira et al.16 concluded in their study that medical CT cannot be used as the

exclusive gold standard for SSCD and that, particularly for small dehiscences on CT.

Moreover, Tavassolie et al.13 also evaluated CT and concluded that there were significant

differences between radiographic and actual length and width, indicating that MSCT tends to

overestimate the size of SSCD and cannot be used exclusively for the diagnosis of SSCD.

Cloutier et al.29 also concluded that with 0.55 mm-collimated helical CT and reformation in

the SSC plane, the risk of over diagnosis is present.

There are only very limited studies regarding CBCT imaging. Dalchow et al18,32 used CBCT

imaging for detection SSCD. It was concluded that CBCT can detect this anatomical

structures with a small radiation dose with a high resolution. In our opinion, it can be

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suggested that CBCT system can be used because of its smaller voxel size and high spatial

resolution in order to detect this kind small anatomical structures.

A limitation of this study can be the use of relatively old CCD camera based CBCT

system rather than using a new flat panel CBCT system. The new flat-panel technology has

allowed smaller FOVs to capture images with less ionizing radiation with a spatial resolution

down to 0.076mm isotropic voxel42. However, this CCD based systems are still on the market

and are still being used among the professions. - Unfortunately, large FOV are often still

reconstructed at larger voxel sizes due to computational limitations (file size and

reconstruction time). Hence, it should be emphasized that with the use of small FOV flat

panel CBCTs the highest detail can be obtained which can be chosen by the professions for

this kind of diagnostic purposes.

Another limitation of this study can be about retrieving the TMJ symptoms. It should

be stated that this kind of studies should be conducted as case control studies. However, this

study is based on retrospective study. The TMJ symptoms of these patients were carefully

noted according to their clinical evaluation and anamnesis files to correlate TMJ symptoms

with SSCD which showed a possible strong correlation. Further studies with larger sample

population must be done as “case-control” studies in order to figure out the detailed

correlation.

As a conclusion, CBCT offers the special advantage of a lower radiation dose, thinner

slices than MDCT and the possibility of importing and exporting individualized, overlap-free

reconstructions and also this imaging system provided increased spatial resolution as

compared to CT22-24. Maxillofacial Radiologists should be aware about these structures which

can be helpful for the interpretation of CBCTs. Further large sample and case control studies

should be done for the precise demonstration of the possible defect and TMJ symptoms using

suitable CBCT imaging with the highest resolution available.

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Figures

Figure 1. Age distribution of study population of 175 patients.

Figure 2. CBCT image showing (a) Plane of Pöschl. Angle of reformation demonstrated on

axial image, (b) Normal pattern is seen as a whole ring on reformatted image (arrow).

Figure 3. CBCT image showing (a) Plane of Stenver. Angle of reformation demonstrated on

axial image, (b) Normal pattern is seen on reformatted image (arrow).

Figure 4. CBCT images showing different radiological patterns of the bony roof of the

superior semicircular canal. a–b normal; c papyraceous; d thick pattern; e pneumatized and f

dehiscent (arrow)

Figure 5. CBCT image showing bilateral superior semicircular canal dehiscence in a 38 year

old female.

Figure 6. Age distribution of 20 patients with superior semicircular canal dehiscence.

Table

Table 1: Clinical data and findings in cases with evidence of SSCD.

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Table I. Clinical data and findings in cases with evidence of SSCD.

Patient

no

Age

(years)

Gender SSCD

location

SSCD length

(mm)

TMJ symptoms TMJ CBCT findings

1 32 Female Right 1.2mm TMJ/ear pain, tinnitus flattening

2 60 Male Right 2.2mm TMJ/ear pain, clicking flattening

3 65 female Left 4.4mm Disequilibrium due to sounds,

clicking

None

4 38 Female Left 1.7mm Disequilibrium due to sounds,

clicking

None

5 29 Female Left 4.3mm TMJ/ear pain, restriction of motion surface

irregularities

6 31 Male Right 2.8mm TMJ/ear pain, restriction of motion surface

irregularities

7 34 Female Right 3.5mm Crepitus , restriction of motion osteophyte

formation

8 42 Female Left 2.7mm Clicking None

9 44 Male Left 4.4mm TMJ/ear pain, restriction of motion osteophyte

formation

10 48 Female Right 2.2mm Clicking, restriction of motion surface

irregularities

11 55 Female Right 5.8mm TMJ/ear pain, tinnitus, clicking flattening

12 50 Female Right 4.8mm TMJ/ear pain, tinnitus, clicking flattening

13 47 Male Left 2.6mm Clicking None

14 38 Male Right 1.9mm Crepitus, restriction of motion surface

irregularities

15 28 Female Left 4.2mm TMJ/ear pain, tinnitus surface

irregularities

16 36 Male Left 5.0mm Disequilibrium due to sounds flattening

17 24 Female Right 3.4mm TMJ/ear pain, restriction of motion flattening

18 28 Female Left 3.2mm TMJ/ear pain, restriction of motion surface

irregularities

19 44 Male Right/Left 1.9/1.8mm TMJ/ear pain, restriction of motion flattening

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20 38 Female Right/Left 4.2/4.4 mm TMJ/ear pain, tinnitus surface

irregularities

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Statement of Clinical Relevance.

A possible connection with TMJ symptoms with superior semicircular canal dehiscence was

defined. Maxillofacial Radiologists should be aware about these structures which can be helpful

for the interpretation of CBCTs.