Anatomo-radiological study of the Superior Semicircular Canal Dehiscence Radiological considerations of Superior and Posterior Semicircular Canals

Comparison of Superior Semicircular Canal Bone Thickness and Patterns in Unilateral and Bilateral Cleft Patients and Normal Controls: A CBCT Study

Superior Semicircular Canal Dehiscence (SSCD) is a recently-defined developmental defect may be associated with several craniofacial anomalies such as Cleft Lip/Palate (CLP). The present study aimed to compare subjects with unilateral and bilateral CLP and normal controls in terms of Superior Semicircular Canal (SSC) bone thickness and pattern.

A total of 238 Cone Beam Computed Tomography (CBCT) images were collected from 52 unilateral Cleft Lip and Palate (UCLP) subjects (104 temporal bones) and 38 Bilateral Cleft Lip and Palate (BCLP) (76 temporal bones) subjects and 148 healthy controls (296 temporal bones). The SSC bone thickness was measured twice and validated by a maxillofacial radiologist. The samples were then classified into five categories based on bone thickness: papyraceous or thin, normal, thick, pneumatized, and dehiscence. After all, the UCLP, BCLP, and normal control groups were compared concerning the SSC pattern and thickness.

The results revealed no significant difference among the three groups regarding the SSC pattern and thickness based on gender. The SSC patterns (P value = .001) and SSC thickness (0.01) were strongly correlated to the cleft type. The thinnest bone thickness and the highest incidence of SSCD were observed among the subjects with BCLP.

The results showed a significant association between the SSC patterns and SSC thickness and the study groups.

The evaluation of superior semicircular canal in patients with unilateral cleft lip and palate using CBCT

OBJECTIVES

The present study aims to evaluate the thickness and radiological patterns of the superior semicircular canal (SSC) in patients with unilateral cleft lip and palate (CL/P).

METHODS

Cone beam computed tomography (CBCT) images of the patients were evaluated in axial and Pöschl planes. CBCT images of 84 patients with unilateral CL/P and 168 healthy individual controls were included in the study. Three study groups were established: the CS-CL/P group (cleft side temporal bones of the CL/P patients), NCS-CL/P (non-cleft side temporal bones of the CL/P patients) and the control group. The radiological patterns of SSCs were categorized as dehiscence, papyraceous, normal, pneumatised and thick. The minimum bone thickness of SSC was measured.

RESULTS

It was found that the CS-CL/P group had a higher prevalence for SSCD compared to both the NCS-CL/P group and the control group. CS-CL/P group had a higher prevalence of dehiscence type and papyraceous type compared to the control group. The SSC thickness on the CS-CL/P patients was thinner than the NCS-CL/P patients and the control group sides (p = 0.033 and p < 0.001, respectively).

CONCLUSIONS

The mean thickness of SSC was found significantly lower in the CS-CL/P group compared to both the NCS-CL/P group and the control group. The elevated prevalence of dehiscence and papyraceous types in the CS-C/LP group compared to the control group implies that the presence of a cleft may be a predisposing factor for these types.

Photon Counting Versus Energy-integrated Detector CT in Detection of Superior Semicircular Canal Dehiscence

BACKGROUND

Superior semicircular canal dehiscence (SSCD), an osseous defect overlying the SSC, is associated with a constellation of audiovestibular symptoms. This study sought to compare conventional energy-integrated detector (EID) computed tomography (CT) to photon-counting detector (PCD)-CT in the detection of SSCD.

MATERIAL AND METHODS

Included patients were prospectively recruited to undergo a temporal bone CT on both EID-CT and PCD-CT scanners. Two blinded neuroradiologists reviewed both sets of images for 1) the presence or absence of SSCD (graded as present, absent, or indeterminate), and 2) the width of the bone overlying the SSC (if present). Any discrepancies in the presence or absence of SSCD were agreed upon by consensus.

RESULTS

In the study 31 patients were evaluated, for a total of 60 individual temporal bones (2 were excluded). Regarding SSCD presence or absence, there was substantial agreement between EID-CT and PCD-CT (k = 0.76; 95% confidence interval, CI 0.54-0.97); however, SSCD was present in only 9 (15.0%) temporal bones on PCD-CT, while EID-CT examinations were interpreted as being positive in 14 (23.3%) temporal bones. This yielded a false positive rate of 8.3% on EID-CT. The bone overlying the SSC was thinner on EID-CT images (0.66 mm; SD = 0.64) than on PCD-CT images (0.72 mm; SD = 0.66) (p < 0.001).

CONCLUSION

The EID-CT examinations tend to overcall the presence of SSCD compared to PCD-CT and also underestimate the thickness of bone overlying the SSC.

Association of the superior semicircular canal and tegmen tympani dehiscences and its relationship with the pneumatisation of the temporal bone

PURPOSE

To analyse the degree of pneumatisation of the temporal bone when there is an association between dehiscence of the superior semicircular canal and dehiscence of the tegmen tympani.

MATERIALS AND METHODS

We analysed a retrospective CT study of 124 selected cases. A single inclusion criterion was applied: the presence of a dehiscence of the tegmen tympani. On the other hand, the degree of temporal pneumatisation was assessed by axial and coronal planes, and has been divided into the following grades O, I, II and III, according to the status and relationship of the mastoid, the bony labyrinth, the petrous segment of the carotid canal and sigmoid sinus.

RESULTS

Of the 124 cases studied, 35 (28.2%) presented both dehiscences. In 26 of the 35 (47.3%), grade II pneumatisation, 4 (14,8%), grade I, and 5 (11,9%) grade III was observed, with a statistically significant relationship (p < 0.001). On the other hand, we did not find a significant relationship when relating both dehiscences in any age or sex group. However, when relating the degree of pneumatisation to sex, among those with grade III pneumatisation, the proportion of men (52.4%) was significantly higher than that of women (47.6%) (p = 0.017).

CONCLUSION

We have detected a statistically significant relationship between the coexistence of grade II pneumatisation and the presence of both dehiscences in the temporal bone.

Superior semicircular canal dehiscence: a radiological and clinical study

Aim

to assess radiologically the prevalence of SSCD with its clinical presentations and its relationship with age.

Methods

a prospective cohort study carried out on 200 consecutive patients (400 temporal bones). Radiological evaluation was performed using High Resolution Computed Tomography (HRCT) with measurement of thickness of bone covering superior semicircular canal (SCC), height and diameter of SSC.

Results

Two hundred patients (400 temporal bones) were involved. The mean thickness ± SD, the mean diameter ± SD and the mean height ± SD were 1.38 ± 0.80 mm, 0.94 ± 0.26 mm and 10.91 ± 2.39 mm respectively. The prevalence of SSCD and predehiscence were 1% and 14% respectively. The commonest symptom encountered was autophony (48.3%). When the SSC thickness, diameter and height were compared with the age of patients, statistically significant differences were detected. The highest diameter, lowest height and lowest thickness were found in patients aged from 54 to 72 years. Thickness of bony layer covering SSC was found to be the most validated measurement for differentiation between cases with positive and negative symptoms with the highest sensitivity and specificity.

Conclusion

The prevalence of SSCD and predehiscence varied among the studies. Autophony is the commonest symptom usually encountered. The condition is acquired rather than congenital. The thickness of bone covering SCC is the most validated measurement in differentiation between cases with positive and negative symptoms.

Video Head Impulse Test Demonstrates a Residual Function after Plugging of Dehiscent Superior Semicircular Canal

OBJECTIVE

Plugging a symptomatic dehiscent superior semicircular canal (SSCC) often leads to a nonfunctional postoperative canal. However, in some instances, a residual function has been described. This study attempts to describe what factors may lead to such residual function.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

Thirty-five patients with confirmed SSCC dehiscence.

INTERVENTION

Video head impulse test was conducted pre- and postoperatively to assess any difference in the function of the SSCC.

MAIN OUTCOME MEASURES

Mean gain and pathological saccades were recorded according to well-established thresholds along with dehiscence length and location to evaluate any associations to residual canal function.

RESULTS

When comparing preoperative to postoperative SSCC abnormal gains, a significant increase was observed after plugging ( p = 0.023). This also held true when abnormal gain and pathologic saccades were taken together ( p < 0.001). Interestingly, 55.3% of patients were observed to remain with a residual SSCC function 4 months postoperatively even with a clinical improvement. Of these, 47.6% had normal gain with pathologic saccades, 38.1% had an abnormal gain without pathologic saccades, and 14.3% had normal gain without pathologic saccades (normal function). Preoperatively, SSCC abnormal gain was associated with a larger dehiscence length mean ( p = 0.002). Anterosuperior located dehiscences were also associated with a larger dehiscence length mean ( p = 0.037). A residual SSCC function after plugging was associated with a shorter dehiscence length regardless of location ( p = 0.058).

CONCLUSION

Dehiscence length and location may be useful in predicting disease symptomatology preoperatively and canals function recovery after plugging. These factors could be used as indicators for preoperative counseling and long-term management.

Evaluation of Superior Semicircular Canal Morphology and Its Relationship with Glenoid Fossa Roof Thickness Using Cone Beam Computed Tomography

Purpose

This study aimed to evaluate the bone thickness of the superior semicircular canal (SSC) roof and its relationship with the roof thickness of the glenoid fossa (RGF).

Methods

The cone beam computed tomography (CBCT) images of 280 patients (560 temporal regions) were surveyed. The lowest thickness of the SSC roof was measured and categorized based on the radiological patterns of the Cisneros et al. classification. The thickness of GF and the presence of dehiscence in this part were determined, as well. The relationship between the thickness of the GF roof and the bone thickness covering the SSC was also assessed.

Results

The mean thickness of the SSC roof was 0.93 ± 0.48 mm, with no significant difference among different age groups and genders (p > 0.05). However, superior semicircular canal dehiscence (SSCD) was more prevalent among females over 45 years old. Similarly, the individuals with the dehiscence of the GF roof had a 12.93-fold higher chance of SSCD development.

Conclusions

The results indicated that the thickness of the bone overlying the SSC was significantly related to the roof thickness of the GF. However, an increase in age resulted in no significant change in the bone thickness of the SSC roof. Gender also had no role in changing the thickness of the bone overlying the SSC. Considering the decrease in the thickness of the SSC roof among females over 45 years of age, menopause may be responsible for this occurrence as well as for the increase in the prevalence of SSCD.

Preoperative Evaluation of Otosclerosis: A National Survey of Otologists

OBJECTIVE

Describe practice patterns in preoperative assessment for stapedectomy.

STUDY DESIGN

Survey.

SETTING

Tertiary referral center.

SUBJECTS

Active members of the American Neurotologic Society and American Otologic Society.

INTERVENTION

Survey.

MAIN OUTCOME MEASURES

Percent of respondents performing preoperative testing with acoustic reflexes (ARs), electrocochleography, vestibular evoked myogenic potentials, and computed tomography (CT). Further analysis of those not ordering routine CT to determine whether imaging would be ordered for previous ear surgery, vestibular complaints, childhood hearing loss, AR inconsistent with otosclerosis, possible advanced otosclerosis, or atypical complaints, including autophony. Further subgroup analysis based on years in practice and practice setting (private versus academic).

RESULTS

Most respondents (56.5%) had practiced more than 15 years and worked in academic settings (69.4%). Rates of routine use of preoperative AR, vestibular evoked myogenic potential, and electrocochleography were 80, 4.7, and 0%, respectively. There were no significant differences based on time in practice or practice settings. For CT, 35.3% reported routine use with a statistically significant difference between academic and private practice respondents (42.4% versus 19.2%, p = 0.040). For CT contingent on specific clinical factors, only AR inconsistent with otosclerosis showed a statistically significant difference between academic and private practice providers (85.3% versus 57.1%, p = 0.020).

CONCLUSION

Most otologists routinely obtain AR before stapedectomy. Academic providers more commonly order CT routinely and for AR inconsistent with otosclerosis. Most respondents not ordering routine CT ordered imaging in specific clinical scenarios. Overall, there is a high level of consistency in preoperative testing regardless of practice setting or time in practice.

New classification of superior semicircular canal dehiscence in HRCT

Background and purpose

The complex anatomy of the temporal bone is difficult to understand and constitutes a challenge in the daily diagnostic routine even for experienced neuroradiologists. In the context of otoneurological (oVEMP) and preoperative diagnostics, the diagnosis of superior semicircular canal dehiscence (SSCD) is of great importance for Ear, Nose, and Throat (ENT) specialists. The gold standard for this diagnosis is a high-resolution CT (HRCT) of the temporal bone. In order to correctly diagnose SSCD, special oblique reconstructions are necessary in addition to standard (axial, coronal, sagittal) reconstructions. We evaluated the frequency of diagnosis and its location in HRCT in correlation with otoneurological examination. From this analysis, we present a new SSCD classification. This classification yields the potential of a differentiated analysis of the patient’s clinical symptoms with correlation to the cross-sectional anatomy and may lead to a differentiated therapy approach.

Study design and setting

We evaluated 1370 temporal bone scans of patients with residual hearing and verified 343 superior semicircular canal dehiscence (SSCD). We conducted a subgroup analysis of these 343 HRCT scans displaying a SSCD and used them as a basis to create a classification.

Results

Three location types of SSCD were identified. These were anterior type 1, superior type 2 and posterior type 3. Type 2 were significantly more frequent in both sexes. SSCD at this location can be overlooked if diagnosis is performed only in the standard axial plane, since it can only be visualized by means of double oblique reconstruction. We present a standardized reconstruction algorithm.

Conclusion

In total, three types of SSCD with differing incidences can be extrapolated from the locations. Superior type 2 is the most frequent one. Both sexes are affected with roughly equal incidence. The use of standardized double oblique reconstruction algorithm ensures that all three types are diagnosed in the HRCT.

Peripheric smell regions in patients with semicircular canal dehiscence: An MRI evaluation

OBJECTIVES

We investigated the peripheric smell regions in patients with semicircular canal dehiscence (SCD) by cranial MRI.

METHODS

In this retrospective study, cranial MRI images of 186 adult patients were included. Group 1 consisted of 83 adult patients with SCD. The control group (Group 2) consisted of 83 healthy subjects without central vertigo. Olfactory bulb (OB) volume and olfactory sulcus (OS) depth were measured in all groups.

RESULTS

In group 1, SCD was detected on the right (33.7%), left (26.5%) sides and bilateral (39.8%). Localization of dehiscence was at superior SC (75.9%), posterior SC (21.7%), lateral SC (1.2%), and posterior + superior SCs (1.2%). OB volumes of the SCD group were significantly lower than the control group bilaterally (p < 0.05). There were no significant differences between OS depths of groups 1 and 2 (p > 0.05). In SCD group, there were positive correlations between OB volumes; OS depths; and OB volumes and OS depths (p < 0.05). In older patients, bilateral OS depth values got lower (p < 0.05). In females, left OB volume values were lower than males (p < 0.05). In right SCD (+) patients, left OS depth values got lower (p < 0.05).

CONCLUSION

We concluded that possible changes in CSF dynamics may cause the development of SCD at thin bone segments; and a decrease in the OB volume. CSF leaks into the perineural sheet of the olfactory bulb (OB) maybe responsible for the decrease in the OB volume. In addition, minor trauma, infection, and inflammation may also be responsible for both coexistences of SCD development and OB volume decrease.

Relationship Between Clinical Features and the Arc and Length of Dehiscence in SCDS: A Single Center Review of 42 Cases

INTRODUCTION

Superior canal dehiscence syndrome (SCDS) is a rare disorder characterized by an array of audiovestibular symptoms due to a dehiscence of bone overlying the superior semicircular canal (SSC). In the presence of debilitating symptoms, surgical management, to plug or resurface the SCC is performed. Although computed tomography (CT) may overestimate the size or presence of a dehiscence due to a partial volume effect, it remains an invaluable diagnostic tool.

OBJECTIVES

To assess for correlation between the arc and length of dehiscence and clinical symptomology.

METHOD

A single-center, single-operator retrospective analysis of 42 patients who underwent trans mastoid plugging of SCC with confirmed radiological dehiscence of their SSC between January 2008 and July 2019 was undertaken. Patients were assessed based on seven predefined clinical symptoms. Length and arc of dehiscence's were evaluated by means of high resolution (0.5 mm) CT (HRCT), using multiplanar reconstruction (MPR). Receiver operating characteristics (ROC), and more specifically the area under the ROC curve (AUROC) were used to assess for statistical significance.

RESULTS

Our results demonstrate overall very little correlation between the arc and size of the dehiscence and symptoms. The only statistically significant correlation we found was between length of dehiscence and the presence of aural fullness.

CONCLUSION

SCDS is a debilitating condition with an array of symptoms on presentation. While dehiscence length demonstrated a correlation with aural fullness, no other symptomology in patients with radiologically evident SCDS demonstrated a statistically significant correlation either against the length or arc of dehiscence.

Relationship Between Superior Semicircular Canal Dehiscence Volume with Clinical Symptoms: Case Series

BACKGROUND

Superior semicircular canal dehiscence (SSCD) is an osseous defect of the arcuate eminence of the petrosal temporal bone. Patients typically present with auditory and vestibular symptoms, such as hearing loss and disequilibrium. Using advanced imaging segmentation techniques, we evaluated whether the volume of SSCD correlated with preoperative symptoms and postoperative outcomes.

METHODS

Our laboratory previously described a novel method of quantifying the size of an SSCD via manual segmentation. High-resolution computed tomography images of the temporal bones were imported into a specialized segmentation software. The volume of the dehiscence was outlined on consecutive slices of the coronal and axial planes via a single-pixel-thick paintbrush tool and was then calculated according to the number of nonzero image voxels.

RESULTS

This study included 111 patients (70 women and 41 men; mean age, 55.1 years; age range, 24-87 years) with a total of 164 SSCDs. Mean postoperative follow-up time was 5.2 months (range, 0.03-59.5 months). The most common preoperative and postoperative symptoms were tinnitus (n = 85) and dizziness (n = 45), respectively. Surgery resulted in improvement of symptoms in most patients. The average volume of 164 SSCDs was 1.3 mm³. SSCD volume was not significantly associated with either preoperative symptoms or postoperative outcomes.

CONCLUSIONS

Advances in imaging techniques have allowed increased visualization of SSCD. Further research will be necessary to evaluate the potential correlation of volume of the dehiscence with clinical variables.

Dehiscence or thinning of bone overlying the superior semicircular canal in idiopathic intracranial hypertension

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

The objective of the study is to evaluate a relationship between idiopathic intracranial hypertension (IIH) and superior semicircular canal dehiscence (SSCD) of bone overlying the superior semicircular canal (SSC).

MATERIALS AND METHODS

A total of 57 (114 ears) individuals, 20 of whom were controls and 37 of whom were IIH, were included in the study. Individuals were evaluated with 0.8 mm slice thickness computed tomography (CT) images for SSC bony roof thickness and SSCD. Thickness of the bony roof over the SSC was graded from Grade 1 to Grade 4. Grade 3 was defined as pre-dehiscence and Grade 4 as dehiscence.

RESULTS

Bony roof thickness was 1.25 mm in the control group and 0.76 mm in the IIH group. When bony roof thickness was compared between the groups, it was found to be significantly thinner in the IIH group (p = 0.012). In the IIH group, while dehiscence was detected in 25 of 74 ears, no dehiscence was detected in 49 ears. In the control group, while dehiscence was detected in 5 ears, no dehiscence was detected in 35 ears. The difference is statistically significant (p = 0.015). The correlation between bony roof thickness and cerebrospinal fluid (CSF) pressure in the IIH group was not statistically significant (p = 0.343; rho = 0.110). The correlation between bony roof thickness and age in the IIH group was not statistically significant (p = 0.082; rho =  - 0.164).

CONCLUSION

Increased CSF pressure in patients with IIH may cause chronic, progressive, and irreversible damage to the bone of the SSC and, according to our study, the rate of SSCD was found to be high in IIH patients.

A Comparison of Diagnostic Accuracy of Superior Semicircular Canal Dehiscence in MDCT and MRI, and Coexistence with Tegmen Tympani Dehiscence

Objective  Tegmen tympani dehiscence in temporal multidetector computed tomography (MDCT) and superior semicircular canal dehiscence may be seen together. We investigated superior semicircular canal dehiscence in temporal MDCT and temporal magnetic resonance imaging (MRI). Methods  In this retrospective study, 127 temporal MRI and MDCT scans of the same patients were reviewed. In all, 48.8% ( n  = 62) of cases were male, and 51.2% ( n  = 65) of cases were female. Superior semicircular canal dehiscence and superior semicircular canal-temporal lobe distance were evaluated by both MDCT and MRI. Tegmen tympani dehiscence was evaluated by MDCT. Results  Superior semicircular canal dehiscence was detected in 14 cases (5.5%) by temporal MDCT and 15 cases (5.9%) by temporal MRI. In 13 cases (5.1%), it was detected by both MDCT and MRI. In one case (0.4%), it was detected by only temporal MDCT, and in two cases (0.8%), it was detected by only temporal MRI. Median superior semicircular canal-to-temporal distance was 0.66 mm in both males and females in temporal MDCT and temporal MRI. In both temporal MDCT and temporal MRI, as superior semicircular canal-to-temporal lobe distance increased, the presence of superior semicircular canal dehiscence in temporal MDCT and temporal MRI decreased. Tegmen tympani dehiscence was detected in eight cases (6.3%) on the right side and six cases (4.7%) on the left side. The presence of tegmen tympani dehiscence in temporal MDCT and the presence of superior semicircular dehiscence in MDCT and MRI increased. Conclusion  Superior semicircular canal dehiscence was detected by both MDCT and MRI. Due to the accuracy of the MRI method to detect superior semicircular dehiscence, we recommend using MRI instead of MDCT to diagnose superior semicircular canal dehiscence. Moreover, there is no radiation exposure from MRI.

Superior Semicircular Canal Dehiscence : Covering Defects in Understanding from Clinical to Radiologic Evaluation

Superior semicircular canal dehiscence alters the normal fluid mechanics of the vestibulocochlear system and can be a debilitating condition. This article reviews the current understanding of the bony labyrinthine defect, including symptoms, etiology, surgical approach, as well as preoperative and postoperative imaging pearls.

Dural Contact to the Malleus Head in Patients with Superior Semicircular Canal Dehiscence (SSCD): Case Series and Review of SSCD and Tegmen Defects

OBJECTIVE

Report a series of cases in which patients have concomitant superior semicircular canal dehiscence (SSCD) and a dehiscent tegmen tympani with Dural contact to the malleus head (DCMH).

METHODS

An analysis of radiologic and audiologic data in 4 patients who presented with SSCD and DCMH at a tertiary care institution. A pertinent literature review was performed.

RESULTS

Four patients (5 ears) had SSCD and DCMH. In 3 patients with unilateral DCMH, the mean maximum air-bone gap was 15 dB in the ear with DCMH compared to 50 dB in the ear without DCMH. Of the 5 ears with DCMH, the mean air conduction threshold at 250 Hz was 17 dB compared to 42 dB in the 3 ears without DCMH.

CONCLUSIONS

We report the findings of DCMH in a series of 4 patients with bilateral SSCD. This limited series suggests that ears with SSCD and DCMH have less of an air-bone gap than would be expected, as 1 would expect an additive effect of DCMH and SSCD on the air-bone gap.

Current Trends, Controversies, and Future Directions in the Evaluation and Management of Superior Canal Dehiscence Syndrome

Patients with superior canal dehiscence syndrome (SCDS) can present with a range of auditory and/or vestibular signs and symptoms that are associated with a bony defect of the superior semicircular canal (SSC). Over the past two decades, advances in diagnostic techniques have raised the awareness of SCDS and treatment approaches have been refined to improve patient outcomes. However, a number of challenges remain. First, there is currently no standardized clinical testing algorithm for quantifying the effects of superior canal dehiscence (SCD). SCDS mimics a number of common otologic disorders and established metrics such as supranormal bone conduction thresholds and vestibular evoked myogenic potential (VEMP) measurements; although useful in certain cases, have diagnostic limitations. Second, while high-resolution computed tomography (CT) is the gold standard for the detection of SCD, a bony defect does not always result in signs and symptoms. Third, even when SCD repair is indicated, there is a lack of consensus about nomenclature to describe the SCD, ideal surgical approach, specific repair techniques, and type of materials used. Finally, there is no established algorithm in evaluation of SCDS patients who fail primary repair and may be candidates for revision surgery. Herein, we will discuss both contemporary and emerging diagnostic approaches for patients with SCDS and highlight challenges and controversies in the management of this unique patient cohort.

Concomitant Dehiscences of the Temporal Bone: A Case-Based Study

Otic capsule dehiscences create a pathological third window in the inner ear that results in a dissipation of the acoustic energy consequent to the lowered impedance. Superior semicircular canal dehiscence (SSCD) was identified by Minor et al in 1998 as a syndrome leading to vertigo and inner ear conductive hearing loss. The authors also reported the relation between the dehiscence and pressure- or sound-induced vertigo (Tullio's phenomenon). Prevalence rates of SSCD in anatomical studies range from 0.4% to 0.7% with a majority of patients being asymptomatic. The observed association with other temporal bone dehiscences, as well as the propensity toward a bilateral or contralateral "near dehiscence," raises the question of whether a specific local bone demineralization or systemic mechanisms could be considered. The present report regard a case of a patient with a previous episode of meningitis, with a concomitant bilateral SSCD and tegmen tympani dehiscence from the side of meningitis. The patient was affected by dizziness, left moderate conductive hearing loss, and pressure/sound-induced vertigo. Because of disabling vestibular symptoms, the patient underwent surgical treatment. A middle cranial fossa approach allowed to reach both dehiscences on the symptomatic side, where bone wax and fascia were used for repair. At 6 months from the procedure, hearing was preserved, and the vestibular symptoms disappeared.

Ocular Vestibular-Evoked Myogenic Potential Amplitudes Elicited at 4 kHz Optimize Detection of Superior Semicircular Canal Dehiscence

Introduction: High-resolution temporal bone computed tomography (CT) is considered the gold standard for diagnosing superior semicircular canal dehiscence (SCD). However, CT has been shown over-detect SCD and provide results that may not align with patient-reported symptoms. Ocular vestibular-evoked myogenic potentials (oVEMPs)—most commonly conducted at 500 Hz stimulation—are increasingly used to support the diagnosis and management of SCD. Previous research reported that stimulation at higher frequencies such as 4 kHz can have near-perfect sensitivity and specificity in detecting radiographic SCD. With a larger cohort, we seek to understand the sensitivity and specificity of 4 kHz oVEMPs for detecting clinically significant SCD, as well as subgroups of radiographic, symptomatic, and surgical SCD. We also investigate whether assessing the 4 kHz oVEMP n10-p15 amplitude rather than the binary n10 response alone would optimize the detection of SCD.

Methods: We conducted a cross-sectional study of patients who have undergone oVEMP testing at 4 kHz. Using the diagnostic criteria proposed by Ward et al., patients were determined to have SCD if dehiscence was confirmed on temporal bone CT by two reviewers, patient-reported characteristic symptoms, and if they had at least one positive vestibular or audiometric test suggestive of SCD. Receiver operating characteristic (ROC) analysis was conducted to identify the optimal 4 kHz oVEMP amplitude cut-off. Comparison of 4 kHz oVEMP amplitude across radiographic, symptomatic, and surgical SCD subgroups was conducted using the Mann-Whitney U test.

Results: Nine hundred two patients (n, ears = 1,804) underwent 4 kHz oVEMP testing. After evaluating 150 temporal bone CTs, we identified 49 patients (n, ears = 61) who had radiographic SCD. Of those, 33 patients (n, ears = 37) were determined to have clinically significant SCD. For this study cohort, 4 kHz oVEMP responses had a sensitivity of 86.5% and a specificity of 87.8%. ROC analysis demonstrated that accounting for the inter-amplitude of 4 kHz oVEMP was more accurate in detecting SCD than the presence of n10 response alone (AUC 91 vs. 87%). Additionally, using an amplitude cut-off of 15uV reduces false positive results and improves specificity to 96.8%. Assessing 4 kHz oVEMP response across SCD subgroups demonstrated that surgical and symptomatic SCD cases had significantly higher amplitudes, while radiographic SCD cases without characteristic symptoms had similar amplitudes compared to cases without evidence of SCD.

Conclusion: Our results suggest that accounting for 4 kHz oVEMP amplitude can improve detection of SCD compared to the binary presence of n10 response. The 4 kHz oVEMP amplitude cut-off that maximizes sensitivity and specificity for our cohort is 15 uV. Our results also suggest that 4 kHz oVEMP amplitudes align better with symptomatic SCD cases compared to cases in which there is radiographic SCD but no characteristic symptoms.

The effect of superior canal dehiscence size and location on audiometric measurements, vestibular-evoked myogenic potentials and video-head impulse testing

PURPOSE

To correlate objective measures of audio-vestibular function with superior canal dehiscence (SCD) size and location in ears with SCD and compare results with literature.

METHODS

We retrospectively evaluated 242 patients exhibiting SCD and/or extremely thinned bone overlying superior canals (SC) on CT scans and selected 73 SCD patients (95 ears with SCD). Data concerning audiometry, impedance audiometry, video-head impulse test (vHIT), cervical vestibular-evoked myogenic potentials (cVEMPs) and ocular VEMPs (oVEMPs) to air- (AC) and bone-conducted (BC) stimuli were collected for each pathologic ear and correlated with dehiscence size and location.

RESULTS

AC pure-tone average (PTA) (p = 0.013), low-frequency air-bone gap (ABG) (p  < 0.001), AC cVEMPs amplitude (p = 0.002), BC cVEMPs amplitude (p < 0.001) and both AC and BC oVEMPs amplitude (p < 0.001) positively correlated with increasing SCD size. An inverse relationship between dehiscence length and both AC cVEMPs and oVEMPs thresholds (p < 0.001) and SC vestibulo-ocular reflex (VOR) gain (p < 0.001) was observed. Dehiscences at the arcuate eminence (AE) exhibited lower SC VOR gains compared to SCD along the ampullary arm (p = 0.008) and less impaired BC thresholds than dehiscences at the superior petrosal sinus (p = 0.04).

CONCLUSION

We confirmed that SCD size affects AC PTA, ABG and both amplitudes and thresholds of cVEMPs and oVEMPs. We also described a tendency for SC function to impair with increasing SCD size and when dehiscence is located at the AE. The latter data may be explained either by a spontaneous canal plugging exerted by middle fossa dura or by a dissipation through the dehiscence of mechanical energy conveyed to the endolymph during high-frequency impulses.

Ambient Pressure Tympanometry Wave Patterns in Patients With Superior Semicircular Canal Dehiscence

Importance: Superior semicircular canal dehiscence (SSCD) is a treatable condition, but current diagnostic modalities have numerous limitations. Clinicians would benefit from an additional tool for diagnostic workup that is both rapid and widely available. Objective: To assess the utility of ambient pressure tympanometry (APT) in the diagnostic workup of SSCD by determining the sensitivity and specificity of APT for SSCD in comparison to other diagnostic modalities. Design: Retrospective cohort study of patients who underwent APT and temporal bone computerized tomography (CT) scans from May 2017 to July 2018. Setting: Tertiary referral center. Participants: APT was performed as part of routine audiological testing on adult patients. We retrospectively analyzed all patients who received both APT and temporal bone CT scans, and divided ears into SSCD and non-SSCD groups based on the presence or absence of radiographic SSCD. Ears with other radiographic findings that could affect tympanic membrane compliance were excluded. Exposures: All patients in this study underwent APT and temporal bone CT scans. Some patients also underwent pure tone audiometry and vestibular evoked myogenic potentials (VEMPs). Main Outcomes and Measures: The primary outcome measures were sensitivity, specificity, and risk ratio of APT for SSCD. Secondary outcome measures include sensitivity of VEMPs and supranormal hearing thresholds. Results: We describe 52 patients (70 ears) who underwent APT and CT imaging (mean age 47.1 years, 67.1% female). APT detected SSCD with 66.7% sensitivity and 72.1% specificity. In symptomatic patients, sensitivity was 71.4% and specificity was 75%. VEMPs performed best at detecting SSCD when defining a positive test as oVEMP amplitude >17 μV, with a sensitivity of 68.2%, similar to APT (p > 0.99). The combination of APT and VEMPs increased sensitivity to 88.9%, better than APT alone (p = 0.031) and trending toward better than VEMPs alone (p = 0.063). Conclusions and Relevance: Rhythmic wave patterns on APT are associated with SSCD and may raise suspicion for this condition in conjunction with consistent results on other diagnostic modalities. Although clinical utility requires confirmation in a larger prospective study, APT is a simple, rapid, and widely available tool warranting further study.

The Prevalence of Superior Semicircular Canal Dehiscence in Patients With Mastoid Encephalocele or Cerebrospinal Fluid Otorrhea

OBJECTIVE

To evaluate the association between mastoid encephalocele or cerebrospinal fluid (CSF) otorrhea and concurrent superior semicircular canal dehiscence (SSCD).

STUDY DESIGN

Retrospective case-control study with chart and imaging review.

SETTING

University-affiliated tertiary referral center.

PATIENTS

A chart review was conducted of all patients greater than 18 years of age who had primary surgery for CSF otorrhea or encephalocele at our university-affiliated tertiary center from 2000 to 2016. Eighty-three patients matched inclusion criteria for case subjects, and 100 patients without CSF otorrhea or encephalocele were included for controls.

MAIN OUTCOME MEASURE

High-resolution computed tomography (CT) scans were reviewed to assess superior semicircular canal roof integrity. Student's t test was used to determine significance of continuous variables. Odds ratio (OR) and χ test was used to determine the association between SSCD and concurrent mastoid encephalocele or CSF otorrhea compared with the control population.

RESULTS

The mean age of the 83 case subjects was 54 years, and 73% were women. In patients with confirmed encephalocele and CSF otorrhea, the prevalence of SSCD was 35%, which was significantly greater than controls (2%) (OR = 26.1, p < 0.001). In patients with only CSF otorrhea, 21% had concurrent SSCD (OR = 10.3, p = 0.001). In patients with SSCD, 46% had bilateral canal dehiscence.

CONCLUSIONS

This is the largest study to evaluate the prevalence of SSCD in patients with concurrent mastoid encephalocele. This study showed a significant association between SSCD and the presence of both mastoid encephalocele and CSF otorrhea. This data suggests that surgeons should have a high suspicion for SSCD in patients presenting with encephalocele or CSF otorrhea.

Inner-Ear Disorders Presenting with Air-Bone Gaps: A Review

Air-bone gaps (ABGs) are commonly found in patients with conductive or mixed hearing loss generally due to outer- and/or middle-ear diseases such as otitis externa, tympanic membrane perforation, interruption or fixation of the ossicular chain, and chronic suppurative otitis media. ABGs can also be found in correlation with inner-ear disorders, such as endolymphatic hydrops, enlarged vestibular aqueduct syndrome, semicircular canal dehiscence, gusher syndrome, cochlear dehiscence, and Paget disease's as well cerebral vascular anomalies including dural arteriovenous fistula. The typical clinical presentation of inner-ear conditions or cerebral vascular anomalies causing ABGs includes audiological and vestibular symptoms like vertigo, oscillopsia, dizziness, imbalance, spinning sensation, pulsatile or continuous tinnitus, hyperacusis, autophony, auricular fullness, Tullio's phenomenon, and Hennebert's sign. Establishing a definitive diagnosis of the underlying condition in patients presenting with an ABG is often challenging to do and, in many patients, the condition may remain undefined. Results from an accurate clinical, audiological, and vestibular evaluation can be suggestive for the underlying condition; however, radiological assessment by computed tomography and/or magnetic resonance imaging is mandatory to confirm any diagnostic suspicion. In this review, we describe and discuss the most recent updates available regarding the clinical presentation and diagnostic workup of inner-ear conditions that may present together with ABGs.

Contribution of Reformatted Multislice Temporal Computed Tomography Images in the Planes of Stenvers and Pöschl to the Diagnosis of Superior Semicircular Canal Dehiscence

OBJECTIVE

In the diagnosis of superior semicircular canal dehiscence (SSCD), computed tomography (CT) is the only imaging method. The aims of the study were to show that reformat images are more accurate than standard planes for diagnosis of SSCD and to determine the prevalence of SSCD.

METHODS

The retrospective review yielded 1309 temporal CTs performed in our radiology department for any reason. Two radiologist interpreted CTs in standard planes collaboratively. Patients with SSCD were reinterpreted in Pöschl and Stenvers planes by 2 radiologists separately.

RESULTS

Statistical analysis was made by accepting that 2 radiologists diagnosis were accurate in Pöschl plane. Coronal plane sensitivity 86%, specificity 64%, Stenvers plane sensitivity 96%, and specificity 52% have been found in the mean result of 2 observers (P < 0.001).

CONCLUSIONS

In the diagnosis of SSCD, standard and Stenvers planes can cause false-negative and false-positive diagnoses. Interpretation in Pöschl plane can significantly increase sensitivity, specificity, negative, and positive predictive values for diagnosing dehiscence.

Endotype-Phenotype Patterns in Meniere's Disease Based on Gadolinium-Enhanced MRI of the Vestibular Aqueduct

Two histopathological subtypes of Meniere's disease (MD) were recently described in a human post-mortem pathology study. The first subtype demonstrated a degenerating distal endolymphatic sac (ES) in the affected inner ear (subtype MD-dg); the second subtype (MD-hp) demonstrated an ES that was developmentally hypoplastic. The two subtypes were associated with different clinical disease features (phenotypes), suggesting that distinct endotype-phenotype patterns exist among MD patients. Therefore, clinical endotyping based on ES pathology may reveal clinically meaningful MD patient subgroups. Here, we retrospectively determined the ES pathologies of clinical MD patients (n = 72) who underwent intravenous delayed gadolinium-enhanced inner ear magnetic resonance imaging using previously established indirect radiographic markers for both ES pathologies. Phenotypic subgroup differences were evidenced; for example, the MD-dg group presented a higher average of vertigo attacks (ratio of vertigo patterns daily/weekly/other vs. monthly, MD-dg: 6.87: 1; MD-hp: 1.43: 1; p = 0.048) and more severely reduced vestibular function upon caloric testing (average caloric asymmetry ratio, MD-dg: 30.2% ± 30.4%; MD-hp: 13.5% ± 15.2%; p = 0.009), while the MD-hp group presented a predominantly male sex ratio (MD-hp: 0.06:1 [f/m]; MD-dg: 1.2:1 [f/m]; p = 0.0004), higher frequencies of bilateral clinical affection (MD-hp: 29.4%; MD-dg: 5.5%; p = 0.015), a positive family history for hearing loss/vertigo/MD (MD-hp: 41.2%; MD-dg: 15.7%; p = 0.028), and radiographic signs of concomitant temporal bone abnormalities, i.e., semicircular canal dehiscence (MD-hp: 29.4%; MD-dg: 3.6%; p = 0.007). In conclusion, this new endotyping approach may potentially improve the diagnosis, prognosis and clinical decision-making for individual MD patients.

Prevalence of Superior Semicircular Canal Dehiscence on High-Resolution CT Imaging in Patients without Vestibular or Auditory Abnormalities

BACKGROUND AND PURPOSE

Prior studies of radiologic superior semicircular canal dehiscence have suggested that CT may overcall dehiscence. However, many of those studies were performed before the advent of multichannel helical CT. Furthermore, there are limited data investigating the prevalence of radiologic superior semicircular canal dehiscence in asymptomatic individuals. The purpose of this study was to determine the rate of radiologic superior semicircular canal dehiscence in an asymptomatic population using 64-channel helical CT.

MATERIALS AND METHODS

We retrospectively enrolled 500 consecutive adult patients without symptoms of superior semicircular canal dehiscence who had undergone CT of the temporal bones in the emergency department of a tertiary academic center between February 2012 and June 2017. The superior semicircular canals were evaluated bilaterally by 2 dedicated head and neck radiologists and subjectively classified as either dehiscent or nondehiscent. A secondary group of 110 scans of patients with symptoms consistent with superior semicircular canal dehiscence was similarly interpreted, and the rate of radiologic superior semicircular canal dehiscence was calculated for each group.

RESULTS

Ten of the 500 asymptomatic patients (2.0%; 95% CI, 1.1%-3.6%) had CT evidence of superior semicircular canal dehiscence, compared with 15 of 110 symptomatic patients (13.6%; 95% CI, 7.8%-21.5%). There was excellent interobserver agreement (κ = 0.91).

CONCLUSIONS

Only 2% of asymptomatic patients had radiologic evidence of superior semicircular canal dehiscence on 64-detector row helical CT. This is markedly lower than previous reports and approaches the postmortem rate of asymptomatic superior semicircular canal dehiscence. We therefore recommend that asymptomatic patients with CT evidence of superior semicircular canal dehiscence undergo audiologic evaluation because the rate of false-positive scans is extremely low.

Superior semicircular canal dehiscence with concomitant otosclerosis-A literature review and case discussion

Computed tomography scan should be performed as a routine before every stapes surgery, in order to exclude concomitant superior semicircular canal dehiscence, since no other clinical, audiological, or electro-physiological criteria are available to exclude concomitant superior semicircular canal dehiscence in the otosclerotic temporal bone.

Radiologic correlation between the thickness of the roof of the glenoid fossa and that of the bony covering of the superior semicircular canal

OBJECTIVES

Dehiscence of the superior semicircular canal (SSC) has been associated with alteration of the temporomandibular joint, although data explaining this association are lacking. The present study examined the correlations between the presence of dehiscences and thickness of the bone covering the SSC and the roof of the glenoid fossa (RGF).

STUDY DESIGN

Computed tomography was used in a cross-sectional analysis of the presence of dehiscences and thickness of the bone overlying the SCC and RGF in 156 temporal bones of 78 patients. The correlations of the presence of dehiscences in the SSC and ipsilateral RGF and the thickness of bone covering the SSC and RGF were analyzed by using the χ² or Fisher's exact test. The relationship between the thickness of the bone overlying the SCC and RGF was analyzed by using the Spearman correlation coefficient and the Kruskal-Wallis test. The relationship between the thickness of the RGF and the covering of the SCC and patient age and gender was analyzed with the general linear model.

RESULTS

Significant correlations were found between the presence of dehiscences and thickness of the bone overlying the SSC and RGF (P < .001).

CONCLUSIONS

There is a morphologic relationship between the structure of the SSC and RGF.

Superior semicircular canal dehiscence: A new perspective

Objective

To determine the use of multi-detector computed tomography (MDCT) in the diagnostic interpretation of superior semicircular canal dehiscence (SSCD) or thinning and its association with ear pathologies and to find whether it is an acquired condition and its association with increase in age.

Materials and methods

study was performed in a tertiary care institute present in a village, following approval of the institutional ethical committee. Retrospective review of temporal bone CT examinations performed between September 2016 and March 2017 was done. 1 mm interval axial images with sagittal and coronal reformatted images were reviewed for the presence of canal dehiscence and thinning by investigators. We characterised the Superior semicircular canal status as normal, frank dehiscence or thinning. Frank dehiscence was further classified anatomically as anterior limb, apex and posterior limb dehiscence.The patient list was then subcategorized into 5 age groups, and the prevalence of SSCD was calculated for each group.

Results

Retrospective review yielded 80 positive cases which included SSC dehiscence (N = 39) and thinning (N = 41). 80 normal scans were selected as control group retrospectively. Statistical analysis was performed to assess for differences between the groups studied. Pearson chi-square test applied. there was a significant association of SSC pathologies prevalence with increasing age (p = < 0.001). No significant relationship was found between SSCD and presence of either CSOM or Cholesteatoma (p = 0.285). Vertigo rather than Tullio phenomenon was the statistically significant complaint (p = <0.001). which brought the patient to the hospital.

Conclusions

The SSCD and thinning belong to the same spectrum and are acquired conditions. Increasing prevalence in old age suggests it to be an acquired condition rather than a congenital one. No significant association of these condition was seen with CSOM and cholesteatoma. Vertigo is the predominat symptom bringing the patient to hospital along with Tullio phenomenon.

CDH23 Related Hearing Loss: A New Genetic Risk Factor for Semicircular Canal Dehiscence?

OBJECTIVE

To investigate the prevalence and relative risk of semicircular canal dehiscence (SCD) in pediatric patients with CDH23 pathogenic variants (Usher syndrome or non-syndromic deafness) compared with age-matched controls.

STUDY DESIGN

Retrospective cohort study.

SETTING

Multi-institutional study.

PATIENTS

Pediatric patients (ages 0-5 years) were compared based on the presence of biallelic pathogenic variants in CDH23 with pediatric controls who underwent computed tomography (CT) temporal bone scan for alternative purposes.

INTERVENTIONS

Retrospective review of diagnostic high resolution CT temporal bone scans and magnetic resonance imaging (MRI) for evaluation of SCD.

MAIN OUTCOME MEASURES

Superior and posterior semicircular canals were evaluated by a neuroradiologist for presence of SCD or abnormal development.

RESULTS

Forty-two CT scans were reviewed for SCD. Eighty-six percent of the CDH23 variant group had abnormalities in at least one canal compared with only 12% in age-matched controls. In the CDH23 variant group there were four patients with superior SCD (57%, RR = 10.0) and three patients with posterior canal abnormalities (43%, RR = 7.5) compared with two, and two patients, respectively, in the control population. Four CDH23 variant children had bilateral abnormalities. One child had thinning or dehiscence in both the superior and posterior canals. Relative risk of SCD in children with CDH23 pathogenic variants is 7.5 (p < 0.001) compared with the pediatric control population.

CONCLUSIONS

Children with a CDH23 pathogenic variants are at significantly increased risk of having SCD and this may be a contributing factor to the vestibular dysfunction in Usher syndrome type 1D patient population.

The Optic Canal Size Is Associated With the Severity of Papilledema and Poor Visual Function in Idiopathic Intracranial Hypertension

BACKGROUND

To determine whether the size of the bony optic canal is associated with the severity of papilledema and poor visual function in idiopathic intracranial hypertension (IIH).

METHODS

We performed a retrospective review of definite patients with IIH with requisite brain magnetic resonance imaging allowing for optic canal measurement. Clinical characteristics and automated (Humphrey) visual field results were reviewed; papilledema was graded according to the modified Frisén scale. Cross-sectional area of the optic canals was measured independently by 2 readers and averaged for each canal. Logistic regression modeling was applied.

RESULTS

Sixty-nine patients with IIH were included (mean age: 33; 91% women; 65% black). Controlling for age, sex, body mass index, race, and cerebrospinal fluid (CSF) opening pressure, each mm increase in canal size was associated with a 0.50 dB reduction in Humphrey visual field mean deviation (P = 0.006); this was likely mediated by the increased odds of Grade 4-5 papilledema or optic atrophy in patients with larger canals (odds ratio: 1.30 [95% CI: 1.10-1.55; P = 0.003] for Grade 4-5 papilledema or atrophy vs grade <4 papilledema per mm increase in canal size).

CONCLUSIONS

Poor visual function and severe papilledema or optic atrophy were associated with a larger optic canal. Potential mechanisms include alteration of local CSF flow or bony remodeling at the optic canals.

Semicircular canal dehiscence among idiopathic intracranial hypertension patients

OBJECTIVES/HYPOTHESIS

The cause of superior semicircular canal dehiscence (SSCD) is unknown. Because of a demonstrated association with tegmental defects and obesity, some have suggested idiopathic intracranial hypertension (IIH) could contribute by eroding the bone over the canal and resulting in SSCD. However, an association between IIH and SSCD has not previously been evaluated. Our objective was to evaluate an association between IIH and SSCD.

STUDY DESIGN

Retrospective cohort.

METHODS

A retrospective study was performed of opening pressures for consecutive patients presenting at a lumbar puncture clinic between August 2012 and October 2015. Imaging for patients who also had thin-sectioned computed tomography (CT) imaging was reviewed for the presence of radiographic SSCD. Association between IIH and SSCD was evaluated using the Student t test and multivariate logistic regression.

RESULTS

One hundred twenty-one patients had both a lumbar puncture performed and thin-sectioned CT imaging available, of which 24 patients (19.8%) met the criteria for IIH with an opening pressure >25 cm H₂ O. The remaining 97 patients (80.2%) did not have elevated opening pressures and served as the control cohort. None of the 24 patients with IIH had radiographic SSCD, whereas eight of the 97 patients (8.2%) without IIH had radiographic SSCD. The average opening pressure in patients without radiographic SSCD was 20.2 cm H₂ O compared to 19.3 cm H₂ O in patients with radiographic SSCD (P = .521). In multivariate logistic regression controlling for age, body mass index, gender, and comorbidities (hypertension, diabetes, hyperlipidemia), opening pressure was not a significant predictor of radiographic SSCD.

CONCLUSIONS

The results of this retrospective pilot study do not suggest an association between IIH and SSCD.

LEVEL OF EVIDENCE

3b. Laryngoscope, 128:1196-1199, 2018.

Influence of Sex and Age on Posterior Semicircular Canal Thickness

OBJECTIVE

The aim of this study is to determine whether sex and age influence posterior semicircular canal (PSC) thickness.

METHODS

This observational study was conducted in 3 tertiary hospitals. The minimal distance between the PSC and the posterior cranial fossa (PSC thickness) was estimated by thin-section multidetector row computed axial tomography (CAT) scan of the temporal bones. Nonselected consecutive patients of all ages (607 temporal bones) were considered.

RESULTS

A significant effect was only detected for sex (F = 5.418, p = 0.020); PSC thickness showed a higher mean value in women (mean difference ± SE: 0.224 ± 0.096 mm). A significant and negative r value was detected for males aged >45 years (-0.173, p = 0.026); in that group of patients, PSC thickness decreased as age increased (0.018 ± 0.008 mm/year). For females aged ≤45 years, a significant and positive r value was found (0.198, p = 0.022); in that group, PSC thickness increased as age increased (0.020 ± 0.008 mm/year).

CONCLUSIONS

PSC thickness did not significantly evolve with age in young males (≤45 years) but it decreased from age 45 years onwards. On the other hand, PCS thickness increased with age in women until the age of 45 years and it did not significantly change in older females.

Superior petrosal sinus causing superior canal dehiscence syndrome

Objective:

To determine signs and symptoms for superior canal dehiscence syndrome caused by the superior petrosal sinus.

Methods:

A review of the English-language literature on PubMed and Embase databases was conducted, in addition to a multi-centre case series report.

Results:

The most common symptoms of 17 patients with superior petrosal sinus related superior canal dehiscence syndrome were: hearing loss (53 per cent), aural fullness (47 per cent), pulsatile tinnitus (41 per cent) and pressure-induced vertigo (41 per cent). The diagnosis was made by demonstration of the characteristic bony groove of the superior petrosal sinus and the ‘cookie bite’ out of the superior semicircular canal on computed tomography imaging.

Conclusion:

Pulsatile tinnitus, hearing loss, aural fullness and pressure-induced vertigo are the most common symptoms in superior petrosal sinus related superior canal dehiscence syndrome. Compared to superior canal dehiscence syndrome caused by the more common apical location of the dehiscence, pulsatile tinnitus and exercise-induced vertigo are more frequent, while sound-induced vertigo and autophony are less frequent. There is, however, considerable overlap between the two subtypes. The distinction cannot as yet be made on clinical signs and symptoms alone, and requires careful analysis of computed tomography imaging.

Idiopathic intracranial hypertension: Contemporary review and implications for the otolaryngologist

OBJECTIVES

1) Review controversies pertaining to the pathophysiology, diagnosis, and treatment of idiopathic intracranial hypertension. 2) Discuss the evolving role of otolaryngologists in managing this disease and related disorders.

DATA SOURCES

Primary literature review, Centers for Disease Control and Prevention website, International Classification of Headache Disorders, Second Edition.

METHODS

A comprehensive review of the primary literature was performed from 1990 to 2016 utilizing keywords idiopathic intracranial hypertension, pseudotumor cerebri, benign intracranial hypertension, spontaneous cerebrospinal fluid leak, and encephalocele. Articles were included at the discretion of the authors based on novel and/or historical contributions to the literature.

RESULTS

The incidence of idiopathic intracranial hypertension is increasing along with the obesity epidemic. Undiagnosed patients may present to otolaryngologists with pulsatile tinnitus, dizziness, sleep apnea, and spontaneous cerebrospinal fluid leaks. Although diagnosis is predicated upon imaging findings and lumbar puncture, radiographic signs including empty sella, optic nerve dilation, and globe flattening may suggest the diagnosis. The most effective intervention is weight loss combined with acetazolamide. Surgery is reserved for severe or refractory symptoms and can be highly morbid. Otolaryngologists are increasingly responsible for managing a number of secondary disorders including cerebrospinal fluid rhinorrhea and otorrhea. Failure to manage intracranial hypertension may lead to adverse surgical outcomes.

CONCLUSIONS

The knowledge base for idiopathic intracranial hypertension has greatly expanded over the past 25 years. This disease is associated with a number of conditions directly relevant to otolaryngologists. A keen understanding of this disorder and its management may optimize outcomes in a growing number of patients. Laryngoscope, 128:248-256, 2018.

Relationship between Surgically Treated Superior Canal Dehiscence Syndrome and Body Mass Index

Objective

Examine the association between body mass index (BMI) and superior canal dehiscence (SCD) among patients who have undergone surgical repair for superior canal dehiscence.

Study Design

Retrospective comparison study.

Setting

Neurotology tertiary care center.

Subjects and Methods

Retrospective review of consecutive adult patients evaluated at our institution for SCD syndrome between November 2006 and August 2015. A control group who underwent imaging within the same period for reasons other than SCD was also included. Patient demographics, weight, and height were examined. We performed multiple subgroup analyses to investigate the relationship of BMI, surgery vs no surgery, and correlation between patient BMI and SCD size.

Results

Of the 268 patients with SCD, 99 underwent surgery; 96 of these patients had complete medical records and were eligible for inclusion. Eighty-eight patients were noted to have arcuate eminence defects, and the mean BMI of this surgical cohort was 28.09 ± 5.26 kg/m2. Nonsurgically treated patients with SCD with available data (n = 94) had a mean BMI of 27.97 ± 6.95 kg/m2. A control group of 204 patients who underwent computed tomography for non-SCD-related causes was analyzed, of whom 155 had available data with a mean BMI of 27.91 ± 6.38 kg/m2.

Conclusion

We demonstrate that adult patients who undergo surgery for SCD are not obese (mean BMI <30), and size of dehiscence poorly correlates with BMI. Our observations call into question the proposed theory that patient weight is a risk factor for the development of symptomatic SCD involving the arcuate eminence.

Spectrum of Third Window Abnormalities: Semicircular Canal Dehiscence and Beyond

Third window abnormalities are defects in the integrity of the bony structure of the inner ear, classically producing sound-/pressure-induced vertigo (Tullio and Hennebert signs) and/or a low-frequency air-bone gap by audiometry. Specific anatomic defects include semicircular canal dehiscence, perilabyrinthine fistula, enlarged vestibular aqueduct, dehiscence of the scala vestibuli side of the cochlea, X-linked stapes gusher, and bone dyscrasias. We discuss these various entities and provide key examples from our institutional teaching file with a discussion of symptomatology, temporal bone CT, audiometry, and vestibular-evoked myogenic potentials.

Lateral Skull Base Attenuation in Superior Semicircular Canal Dehiscence and Spontaneous Cerebrospinal Fluid Otorrhea

Objectives

(1) To quantitatively assess the lateral skull base thickness in patients with superior semicircular canal dehiscense (SSCD) using a standardized and validated radiographic measure and to compare it with that of a population with spontaneous cerebrospinal fluid otorrhea (CSFO). (2) To analyze demographic and clinical factors associated with skull base thickness in the SSCD group.

Study Design

Case series with chart review.

Setting

Tertiary neurotologic referral center.

Subjects and Methods

Based on computed tomography imaging of the tegmen, mean skull base thickness was calculated for 16 patients with radiographic and clinical SSCD. Similar measures were performed in 4 comparison groups consisting of adults with spontaneous CSFO (n = 33), as well as 3 control groups recruited from our adult cochlear implant database: 30 obese controls (body mass index [BMI] >30 kg/m2), 11 overweight controls (BMI, 25-30 kg/m2), and 20 normal weight controls (BMI <25 kg/m2).

Results

The SSCD group had a significantly lower mean BMI (28.6 kg/m2) than the spontaneous CSFO group (37.7 kg/m2; P = .0007). The mean skull base thickness of SSCD patients was 17% thinner than that of the CSFO group, 31% thinner vs obese controls, 49% thinner vs overweight controls, and 45% thinner vs normal weight controls. These differences were all statistically significant ( P < .05).

Conclusion

Patients with SSCD have a marked thinning of the lateral skull base, more so than patients with spontaneous CSF otorrhea and control groups with different BMIs. Skull base attenuation in SSCD patients did not correlate with BMI.