Clinical Manifestations of Superior Semicircular Canal Dehiscence

Decision Making in Patients With Concomitant Otosclerosis and Superior Semicircular Canal Dehiscence: A Systematic Review of the Literature

OBJECTIVE

Concomitant otosclerosis (OTS) and superior semicircular canal dehiscence (SSCD) is a rare, but difficult-to-identify and treat diagnosis. A systematic review of the literature was performed to analyze the diagnostic and therapeutic approaches of concurrent OTS and SSCD cases and to identify possible factors that may help in predicting the surgical outcome.

DATA SOURCES

PubMed, Scopus, Medscape, Ovid databases.

STUDY SELECTION

Studies showing diagnosis of OTS documented by audiometric test with or without associated radiological signs (computed tomography), and concomitant diagnosis of SSCD, documented at least by high-resolution computed tomography (and possibly supported by neurophysiological testing) were included. Both surgically treated and untreated patients were considered for data analysis.

DATA EXTRACTION

The general characteristics of each study were recorded, when available. Clinical, audiological, vestibular testing, surgical, and radiological data were extracted from the published case reports and series, and recorded on a database. For each case, the diagnostic steps that confirmed OTS and concomitant SSCD in the same ear were extracted.

DATA SYNTHESIS

Twelve studies were included in the review and 18 cases affected simultaneously by the 2 conditions were extracted and analyzed. Seven of 12 ears (58.3%) undergoing stapes surgery experienced a hearing improvement. In four (33.3%) cases, vestibular symptoms (with or without associated acoustic symptoms) of SSCD were unmasked or worsened by stapes surgery.

CONCLUSIONS

A reliable preoperative diagnosis of the two concomitant conditions is possible with a proper interpretation of clinical signs, audiometric, and vestibular testing, in association with the radiologic assessment. Despite that the length and the location of the dehiscence may guide the surgical decision, definitive conclusions regarding the appropriate indications for surgical treatment cannot be drawn due to the limited number of cases with adequate data reported in the literature.

Radiologically-proven New Development of Superior Semicircular Canal Dehiscence Associated With Development of Superior Semicircular Canal Dehiscence Syndrome

OBJECTIVE

This report describes a case of development of radiologic superior semicircular canal dehiscence and reviews the literature for pertinent clinical and radiologic findings in patients with superior semicircular canal dehiscence syndrome (SCDS).

PATIENT

A 28-year-old man presented with auditory and vestibular symptoms of SCDS and underwent a high-resolution temporal bone computed tomography scan that showed frank dehiscence of the right superior semicircular canal. Diagnosis of SCDS was further verified with audiometric and cervical vestibular-evoked myogenic potential (cVEMP) thresholds. The patient had previously undergone a computed tomography scan 12 years prior for work-up of sudden sensorineural hearing loss that showed no evidence of superior semicircular canal dehiscence bilaterally.

INTERVENTIONS

A combination of diagnostic and therapeutic interventions was conducted consisting of preoperative audiometric and cVEMP thresholds, followed by middle fossa craniotomy for surgical repair of the dehiscence.

MAIN OUTCOME MEASURE

Postoperative audiometric and cVEMP thresholds and symptomatic improvement of SCDS after surgical repair of the dehiscence.

RESULTS

The patient reported resolution of his clinical symptoms after surgical repair of the dehiscence. Postoperative cVEMP thresholds improved to the normal range and the mild low-frequency conductive hearing loss resolved.

CONCLUSIONS

To our knowledge, this case report is the first description of radiologically proven new development of superior canal dehiscence. Further prospective studies that include serial imaging examinations may help with visualizing and understanding the temporal evolution of superior canal dehiscence, and better elucidate the relationship between development/ progression of superior canal dehiscence and onset of clinical symptoms.

On the Relationship Between Menière's Disease and Endolymphatic Hydrops

: The relationship between Menière's disease and endolymphatic hydrops is ambiguous. On the one hand, the existence of cases of endolymphatic hydrops lacking the classic symptoms of Menière's disease has prompted the assertion that endolymphatic hydrops alone is insufficient to cause symptoms and drives the hypothesis that endolymphatic hydrops is a mere epiphenomenon. Yet, on the other hand, there is considerable evidence suggesting a relationship between the mechanical pressure effects of endolymphatic hydrops and resultant disordered auditory physiology and symptomatology. A critical appraisal of this topic is undertaken, including a review of key histopathologic data chiefly responsible for the epiphenomenon hypothesis. Overall, a case is made that A) the preponderance of available evidence suggests endolymphatic hydrops is likely responsible for some of the auditory symptoms of Menière's disease, particularly those that can be modulated by mechanical manipulation of the basilar membrane and cochlear microphonic; B) Menière's disease can be reasonably considered part of a larger spectrum of hydropic inner ear disease that also includes some cases that lack vertigo. C) The relationship with endolymphatic hydrops sufficiently robust to consider its presence a hallmark defining feature of Menière's disease and a sensible target for diagnostic detection.

Underwater Endoscopic Repair of Superior Canal Dehiscence

: Superior canal dehiscence (SCD) is a bony defect of the superior semicircular canal (SCC). Patients with SCD Syndrome (SCDS) may experience symptoms such as aural fullness, pulsatile tinnitus, hyperacusis, autophony, or pressure or noise-induced vertigo . The defect can be repaired in various ways, but there is potential for loss of perilymphatic fluid during transmastoid approaches that could result in postoperative sensorineural hearing loss . We hypothesize that if the procedure were performed "underwater" in balanced salt solution (BSS), loss of perilymphatic fluid would be minimized. CASE REPORT:: A 55-year-old male presented with right-sided autophony, pulsatile tinnitus, and hyperacusis. Audiometric testing demonstrated a low-frequency airbone gap and a supranormal bone-conduction threshold at 4 kHz. Ocular VEMP responses were increased amplitude. Temporal bone imaging revealed a SCC dehiscence.The patient was taken to the operating room for an underwater, endoscopic repair of the SCC using a transmastoid approach. A cortical mastoidectomy was performed using Landmarx image navigation. BSS filled the mastoid and a 0-degree endoscope with endoscrub was used to see the SCC underwater. The SCC was entered near the ampullated end with a bur. A stepwise plugging process included applying strips of wet and dried fascia and bone dust. The non-ampullated end was similarly plugged. BSS was suctioned, and under microscopic visualization, labyrinthotomies were capped with bone chips. The patient tolerated the procedure well and was discharged the next day. There was no sensorineural hearing loss postoperatively. CONCLUSION:: SCDS may be addressed surgically using multiple approaches. An underwater endoscopic repair of the SCC may be safe and effective surgical treatment.SDC video link: http://links.lww.com/MAO/A808.

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.

Case Report: Local Anesthesia Round Window Plugging and Simultaneous Vibrant Soundbridge Implant for Superior Semicircular Canal Dehiscence

The aim of the present study is to report the outcomes of round window reinforcement surgery performed with the application of a Vibrant Soundbridge middle ear implant (VSB; MED-EL) in a patient with superior semicircular canal dehiscence (SSCD) who presented with recurrent vertigo, Tullio phenomenon, Hennebert's sign, bone conduction hypersensitivity, and bilateral moderate to severe mixed hearing loss. Vestibular evoked myogenic potentials (VEMPs) and high-resolution computed tomography (HRCT) confirmed bilateral superior semicircular canal dehiscence while this was not seen in magnetic resonance imaging. The surgical procedure was performed in the right ear as it had worse vestibular and auditory symptoms, a poorer hearing threshold, and greatly altered HRCT and VEMPs findings. With local-assisted anesthesia, round window reinforcement surgery (plugging) with perichondrium was performed with simultaneous positioning of a VSB on the round window niche. At the one and 3 months follow-up after surgery, VSB-aided hearing threshold in the right ear improved to mild, and loud sounds did not elicit either dizziness or pain in the patient.

Positional nystagmus in middle ear cholesteatoma with labyrinthine fistula

Chronic otitis media with cholesteatoma can cause erosion of the dense labyrinthine bone overlying the inner ear organs, and this labyrinthine fistula allows pressure or mass-induced motion of the underlying perilymphatic and endolymphatic compartment, evoking vestibular symptoms. While the mechanism of a positive fistula test, which is conducted by increasing or decreasing the external auditory canal pressure, has been well established, the mechanism underlying positional nystagmus in labyrinthine fistula has not been discussed yet. In the present study, we propose a new hypothesis accounting for positional nystagmus in labyrinthine fistula involving the lateral semicircular canal (LSCC), i.e., the change in intracranial cerebrospinal fluid pressure by position change is transmitted to the perilymphatic space, causing ampullopetal (excitatory) or ampullofugal (inhibitory) deflection of the LSCC cupula.

Cervical and Ocular Vestibular-Evoked Myogenic Potentials in Patients With Intracochlear Schwannomas

Objective: To evaluate ocular and cervical vestibular evoked myogenic potentials (oVEMPs and cVEMPs) in patients with solely intracochlear localization of an intralabyrinthine schwannoma (ILS).

Study Design: Retrospective analysis of a series of cases.

Setting: Monocentric study at a tertiary referral center.

Patients: Patients with intracochlear schwannoma (ICS) and VEMP measurements.

Outcome Measures: Signed asymmetry ratio (AR) of cVEMPs and oVEMPs to air conducted sound with AR cut-offs considered to be asymmetrical when exceeding ±30% for cVEMPs and ±40% for oVEMPs with respect to the side affected by the tumor (reduced amplitudes on the affected side indicated by negative values, enhanced amplitudes by positive values); VEMP amplitudes and latencies; tumor localization in the cochlear turn and scala.

Results: Nineteen patients with a solely intracochlear tumor (ICS patients) [10 males, 9 females, mean age 57.1 (SD: 13.4) years] were included in the study. On the affected side, cVEMPs were absent or reduced in 47% of the patients, normal in 32%, and enhanced in 21%. Ocular VEMPs on the affected side were absent or reduced in 53% of the patients, normal in 32% and enhanced in 15%. Latencies for cVEMPs and oVEMPs were not significantly different between the affected and non-affected side. In all patients with enhanced VEMPs, the tumor was located in the scala tympani and scala vestibuli.

Conclusions: As a new and unexpected finding, VEMP amplitudes can be enhanced in patients with intracochlear schwannoma, mimicking the third window syndrome.

Impact of Superior Canal Dehiscence Syndrome on Health Utility Values: A Prospective Case-Control Study

Introduction: Superior canal dehiscence syndrome (SCDS) is a condition characterized by a defect in the bone overlying the superior semicircular canal, creating a third mobile window into the inner ear. Patients can experience disabling symptoms and opt for surgical management. Limited data are available on the impact of SCDS on health-related quality of life (HRQoL) and disease-specific HRQoL more specifically.

Objective: To perform a prospective analysis on generic HRQoL in SCDS patients compared to healthy age-matched controls.

Methods: A prospective study was performed on patients diagnosed with SCDS and who did not undergo reconstructive surgery yet. Patients were recruited between November 2017 and January 2020 and asked to complete the Health Utility Index (HUI) Mark 2 (HUI2)/Mark 3 (HUI3) questionnaire. For the control group, age-matched participants without otovestibular pathology or other chronic pathology were recruited. The multi-attribute utility function (MAUF) score was calculated for the HUI2 and HUI3. Results of both groups were compared using the Mann-Whitney U test.

Results: A total of 20 patients completed the questionnaire. Age ranged from 37 to 79 years with a mean age of 56 years (45% males and 55% females). The control group consisted of 20 participants with a mean age of 56.4 years and ranged from 37 to 82 years (35% males and 65% females). For the case group, median HUI2 MAUF score was 0.75 and median HUI3 MAUF score was 0.65. For the control group, the median scores were 0.88 and 0.86 respectively. There was a statistically significant difference for both HUI2 (p = 0.024) and HUI3 (p = 0.011). SCDS patients had a worse generic HRQoL than age-matched healthy controls. One patient with unilateral SCDS had a negative HUI3 MAUF score (−0.07), indicating a health-state worse than death.

Conclusion: SCDS patients have significantly lower health utility values than an age-matched control group. This confirms the negative impact of SCDS on generic HRQoL, even when using an instrument that is not designed to be disease-specific but to assess health state in general. These data can be useful to compare impact on HRQoL among diseases.

Biomechanics of Third Window Syndrome

Third window syndrome describes a set of vestibular and auditory symptoms that arise when a pathological third mobile window is present in the bony labyrinth of the inner ear. The pathological mobile window (or windows) adds to the oval and round windows, disrupting normal auditory and vestibular function by altering biomechanics of the inner ear. The most commonly occurring third window syndrome arises from superior semicircular canal dehiscence (SSCD), where a section of bone overlying the superior semicircular canal is absent or thinned (near-dehiscence). The presentation of SSCD syndrome is well characterized by clinical audiological and vestibular tests. In this review, we describe how the third compliant window introduced by a SSCD alters the biomechanics of the inner ear and thereby leads to vestibular and auditory symptoms. Understanding the biomechanical origins of SSCD further provides insight into other third window syndromes and the potential of restoring function or reducing symptoms through surgical repair.

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.

Membranous or Hypermobile Stapes Footplate: A New Anatomic Site Resulting in Third Window Syndrome

Objectives: To describe a potentially underappreciated pathology for post-traumatic persistent intractable dizziness and third window syndrome as well as the methods to diagnose and surgically manage this disorder. Study Design: Observational analytic case studies review at a tertiary care medical center. Methods: Patients suffering persistent dizziness following head trauma and demonstrating Tullio phenomena or Hennebert signs are included. All had reportedly normal otic capsules on high resolution temporal bone CT scans (CT). The gray-scale invert function was used to visualize the stapes footplate, which helped determine the diagnosis. Gray-scale inversion can be used to improve visualization of temporal bone anatomy and pathologic changes when diagnoses are in doubt. A search to check for the presence of perilymph leakage was performed in all cases. This was accomplished using intraoperative Valsalva maneuvers. Fat grafting of round and oval windows was performed. Results: Over an 11-year period between January 2009 and December 2019, 28 patients (33 ears) were treated. Follow-up with balance testing and audiograms were performed 6-8 weeks following surgery. Follow-up ranged from 6 months to 7 years. Prior to surgery all patients reported dizziness in response to loud sounds and/or barometric pressure changes. Seven out of 33 ears had demonstrable perilymph leakage into the middle ear; the rest (26 ears) appeared to have membranous or hypermobile stapes footplates. Membranous stapes footplates were better visualized using the invert function on CT. Thirteen patients had a fistula sign positive bilaterally while 15 had unilateral pathology. Twenty-four of the 28 patients (85.7%) showed both subjective and objective improvement following surgery. No patients suffered from a deterioration in hearing. Conclusions: A previously underappreciated membranous or hypermobile stapes footplate can occur following head trauma and can cause intractable dizziness typical of third window syndrome (TWS). Durable long term success can be achieved by utilizing fat graft patching of the round and oval windows. High resolution temporal bone CT scans using the gray-scale inversion (invert) function can assist in preoperative diagnosis.

Utricular Sensitivity during Hydrodynamic Displacements of the Macula

To explore the effects of cochlear hair cell displacement, researchers have previously monitored functional and mechanical responses during low-frequency (LF) acoustic stimulation of the cochlea. The induced changes are believed to result from modulation of the conductance of mechano-electrical transduction (MET) channels on cochlear hair cells, along with receptor potential modulation. It is less clear how, or if, vestibular hair cell displacement affects vestibular function. Here, we have used LF (<20 Hz) hydrodynamic modulation of the utricular macula position, whilst recording functional and mechanical responses, to investigate the effects of utricular macula displacement. Measured responses included the Utricular Microphonic (UM), the vestibular short-latency evoked potential (VsEP), and laser Doppler vibrometry recordings of macular position. Over 1 cycle of the LF bias, the UM amplitude and waveform were cyclically modulated, with Boltzmann analysis suggesting a cyclic modulation of the vestibular MET gating. The VsEP amplitude was cyclically modulated throughout the LF bias, demonstrating a relative increase (~20-50 %; re baseline) and decrease (~10-20 %; re baseline), which is believed to be related to the MET conductance and vestibular hair cell sensitivity. The relationship between macular displacement and changes in UM and VsEP responses was consistent within and across animals. These results suggest that the sensory structures underlying the VsEP, often thought to be a cranial jerk-sensitive response, are at least partially sensitive to LF (and possibly static) pressures or motion. Furthermore, these results highlight the possibility that some of the vestibular dysfunction related to endolymphatic hydrops may be due to altered vestibular transduction following mechanical (or morphological) changes in the labyrinth.

Sealing of superior semicircular canal dehiscence is associated with improved balance outcomes postoperatively versus plugging of the canal in middle fossa craniotomy repairs: a case series

OBJECTIVE

The authors compared postoperative symptoms between patients with sealed and those with plugged semicircular canal dehiscence repairs.

METHODS

In total, 136 ears from 118 patients who underwent surgical repair for semicircular canal dehiscence were identified via chart review. Data from postoperative MRI scans showing preservation or loss of semicircular canal fluid signal and postoperative reports of autophony, amplification, aural fullness, tinnitus, hyperacusis, hearing loss, vertigo, dizziness, disequilibrium, oscillopsia, and headache were amalgamated and analyzed.

RESULTS

Patients with preservation of fluid signal were far less likely to have dizziness postoperatively (p = 0.007, OR 0.158, 95% CI 0.041-0.611). In addition, these patients were more likely to have tinnitus postoperatively (p = 0.028, OR 3.515, 95% CI 1.145-10.787).

CONCLUSIONS

The authors found that superior semicircular canal dehiscence patients who undergo sealing without plugging have improved balance outcomes but show more tinnitus postoperatively than patients who undergo plugging.

Endolymphatic hydrops mimicking obstructive Eustachian tube dysfunction: preliminary experience and literature review

PURPOSE

Aural fullness is a common symptom of middle ear diseases, most importantly Eustachian tube dysfunction (ETD). Yet, aural fullness may also be caused by inner ear disorders, such as hydropic ear diseases. Here, we report our experience with endolymphatic hydrops (EH) mimicking ETD. Furthermore, we review the literature related to (i) EH as a differential diagnosis of symptoms suggesting ETD and (ii) the pathophysiology and treatment of aural fullness due to inner ear disorders.

METHODS

We retrospectively included adult patients with aural fullness as chief complaint and radiographically diagnosed EH. Hearing and Eustachian tube function were assessed using audiometry, tympanometry, and tubomanometry. Primarily suspected ETD was treated by balloon dilatation of the Eustachian tube (BDET). The endolymphatic space of the inner ear was imaged using gadolinium-enhanced MRI (Gd-MRI) including a 3D-real inversion-recovery sequence after intravenous gadolinium administration.

RESULTS

We report three affected ears of two patients (two females, age 42 and age 51) with aural fullness as chief complaint. Audiometry of main speech frequencies was normal in all affected ears. In one ear, there was a type A tympanogram and in two ears, there was a type B tympanogram. In both patients, medical treatment for ETD and BDET were unsuccessful. Gd-MRI of the inner ears revealed cochlear EH in 3/3 ears affected by aural fullness, but not in the unaffected ear.

CONCLUSION

EH may underlay cases with aural fullness and could in these cases explain unsuccessful treatment for ETD. As ETD is often treated by invasive procedures, distinguishing ETD from EH as the underlying cause of aural fullness is important. Our findings raise the question whether Gd-MRI to rule out EH is indicated in patients with unexplained aural fullness, in particular after unsuccessful interventional treatment for ETD.

Validating the Utility of High Frequency Ocular Vestibular Evoked Myogenic Potential Testing in the Diagnosis of Superior Semicircular Canal Dehiscence

INTRODUCTION

Ocular vestibular evoked myogenic potential (oVEMP) is a diagnostic test employed in the evaluation of superior semicircular canal dehiscence (SSCD) syndrome. Previous work showed that the presence of the n10 component of oVEMP at 4000 Hz was diagnostic of SSCD with perfect sensitivity and specificity of 1.0 in a series of 22 patients. This study sought to validate the diagnostic accuracy of high-frequency oVEMP with comparison to 500 Hz oVEMP and cervical vestibular evoked myogenic potential (cVEMP) in a larger series of patients.

METHODS

Retrospective chart review of 171 patients with clinical symptoms consistent with SSCD who underwent oVEMP and cVEMP testing. Dehiscence of the superior semicircular canal (SCC) on high-resolution computed tomography (CT) imaging of the temporal bone was used to identify cases of likely SSCD. The presence or absence of 4000 Hz oVEMP n10 responses, increased amplitude of 500 Hz oVEMP responses, and reduced threshold of 500 Hz cVEMP responses were identified for each patient.

RESULTS

SCC dehiscence was identified by CT imaging in 48 of 171 patients with symptoms consistent with SSCD. High-frequency oVEMP testing at 4000 Hz elicited a n10 response in 40 of 48 (83.3%) of patients and was present in 48 of 171 (28.1%) patients overall. The corresponding sensitivity was 0.83, specificity was 0.93, positive predictive value was 0.83, and negative predictive value was 0.93. oVEMP and cVEMP testing at 500 Hz was less accurate with sensitivity of 0.62 and 0.64, respectively, and specificity of 0.73 and 0.73, respectively.

CONCLUSION

The presence of a 4000 Hz oVEMP n10 response was predictive of SSC dehiscence on CT imaging among patients with symptoms consistent with SSCD with sensitivity of 0.83, specificity of 0.93, positive predictive value of 0.83, and negative predictive value of 0.93. A negative finding strongly rules out SSCD. High-frequency oVEMP was more accurate than 500 Hz oVEMP or cVEMP.

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.

A Basis for Standardizing Superior Semicircular Canal Dehiscence Management

OBJECTIVES

(1) To determine how otologic/neurotologic surgeons counsel patients with superior semicircular canal dehiscence (SSCD). (2) To understand the plethora of presenting symptoms associated with SSCD and appropriate management. (3) To suggest appropriate management; oftentimes avoiding surgery.

METHODS

This was a survey study of both community and academic physicians. A 23-question survey was distributed to all members of the American Neurotological (ANS) and American Otologic Societies (AOS) via email in the Fall of 2018. A total of 54 responses were received from a possible pool of 279 for a response rate of 19.4%. Inferences were made about the population through sample proportions and confidence intervals.

RESULTS

All respondents use computed tomography (CT) in diagnosing SSCD and 11.1% use CT exclusively. Cervical vestibular evoked myogenic potential (VEMP; 77.8%) are used more often than ocular VEMPs (38.9%). Magnetic resonance imaging (7.4%) is used infrequently; 96.3% of surgeons surveyed have seen patients with SSCD on imaging that are asymptomatic. Following surgical treatment, respondents reported balance issues and mild-to-moderate high-frequency sensorineural hearing loss (88.4%); 32.6% reported that the majority (>50%) of their patients needed further intervention after surgery, typically aggressive vestibular rehabilitation.

CONCLUSIONS

There is a discrepancy in the systematic approach to SSCD between both the surgeons and the published literature. Patients with SSCD on ultra-high-resolution CT may have myriad symptoms while others are asymptomatic, and surgery may lead to additional complications. We will present a methodical recommendation to assist in the management of patients with SSCD depending upon their symptoms. This may improve patient selection, counseling, and outcomes.

Superior Canal Dehiscence Surgery Outcomes Following Failed Round Window Surgery

OBJECTIVE

Round window (RW) occlusion or reinforcement is a less-invasive option compared with direct repair approaches to improve symptoms of superior canal dehiscence (SCD) syndrome. However, RW surgery is associated with variable outcomes. Middle fossa craniotomy or transmastoid repair is an option for SCD patients who fail RW surgery, but it is unknown whether sequential repair following RW plugging improves SCD symptoms or increases complications. The objective of this study is to evaluate outcomes of SCD repair via middle fossa craniotomy following failed RW surgery.

STUDY DESIGN

Retrospective review.

SETTING

Academic tertiary care center.

PATIENTS

Adult patients with SCD syndrome who underwent failed RW surgery followed by sequential middle fossa craniotomy and plugging of the arcuate eminence defect. Patients with SCD associated with the superior petrosal sinus were excluded.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Prospectively collected pre- and postoperative symptom questionnaires, threshold audiograms, and cervical vestibular evoked myogenic potentials (cVEMP).

RESULTS

Seven SCD patients (out of a total of 194 surgical cases at our institution) underwent sequential middle-fossa SCD repair following failed RW surgery. Resolution of symptoms and reversal of diagnostic indicators were observed in the majority of subjects following sequential repair. Two of seven patients underwent a third procedure with plugging of the superior semicircular canal by a transmastoid approach due to the presence of residual symptoms.

CONCLUSION

Middle fossa craniotomy and SCD occlusion is a safe and reasonable option for patients who fail RW surgery. Our cohort did not show increased risks of auditory or vestibular dysfunction.

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.

Flat Panel Computed Tomography in the Diagnosis of Superior Semicircular Canal Dehiscence Syndrome

HYPOTHESIS

Flat panel computed tomography (FPCT) provides more accurate measurements of dimensions for superior semicircular canal dehiscence (SCD) than multislice CT (MSCT).

BACKGROUND

SCD syndrome occurs when a bony defect of the superior semicircular canal causes vestibular and auditory symptoms. MSCT can overestimate the size of the canal defect, with possible over-diagnosis of SCD and suboptimal selection of surgical approach. The higher resolution of FPCT should afford more accurate measurements of these defects.

METHODS

Radiographic and surgical measurements were compared in 22 patients (mean age 49.4) with clinical SCD syndrome and canal defects confirmed at surgery. Twenty second FPCT scans were acquired before surgery with parameters: 109Kv, small focus, 200 degrees rotation angle, and 0.4 degree per frame angulation step. Dehiscence dimensions were measured from orthogonal multiplanar reconstructions on a high-resolution liquid crystal display monitor and compared with actual measurements recorded during microsurgery.

RESULTS

SCD dimensions by FPCT (x) were 2.8 ± 1.6 mm for length and 0.72 ± 0.28 mm for width. The surgical measurements (y) were 2.8 ± 1.7 mm for length and 0.72 ± 0.34 mm for width. Linear fits between x and y yielded R values of 0.93 (length) and 0.66 (width). Our previous study using MSCT had R values of 0.28 (length) and 0.48 (width). The average difference between each FPCT and corresponding surgical measurement was not significantly different from zero, whereas the results for MSCT were significantly different.

CONCLUSION

FPCT can provide more accurate measurements of SCD than MSCT. Clinicians should consider using FPCT for imaging suspected SCD.

Clinical and Physiologic Predictors and Postoperative Outcomes of Near Dehiscence Syndrome

OBJECTIVE

To identify predictors of near dehiscence (ND) or thin rather than dehiscent bone overlying the superior semicircular canal in patients with signs and symptoms suggestive of superior semicircular canal dehiscence syndrome (SCDS), as well as postoperative outcomes.

STUDY DESIGN

Retrospective case-control study.

SETTING

Tertiary referral center.

PATIENTS

All 288 patients who underwent middle cranial fossa approach for repair of SCDS (1998-2018) were reviewed for cases of ND. Demographics, symptoms, and clinical signs including nystagmus, ocular vestibular-evoked myogenic potential (oVEMP) amplitude, cervical vestibular-evoked myogenic potential (cVEMP) thresholds, and low-frequency air-bone gap were compared before and after surgery.

MAIN OUTCOME MEASURE

Presence of preoperative ND and postoperative symptoms and physiologic measures.

RESULTS

Seventeen cases of ND (16 patients, 17 ears) and 34 cases (34 ears) of frank SCDS were identified. ND cases differed from frank dehiscence cases in that they were less likely to have nystagmus in response to ear canal pressure or loud sounds, OR = 0.05 (95% CI 0.01-0.25) and Valsalva, OR = 0.08 (0.01-0.67), smaller peak-to-peak oVEMP amplitudes, OR = 0.84 (0.75-0.95), and higher cVEMP thresholds, OR = 1.21 (1.07-1.37). Patients with ND had similar symptoms to those with frank SCDS before surgery, and after surgery had outcomes similar to patients with frank SCDS.

CONCLUSIONS

In patients with symptoms consistent with SCDS, predictors of ND include absence of nystagmus in response to pressure/loud sounds, greater cVEMP thresholds, and smaller oVEMP amplitudes. We propose ND is on a spectrum of dehiscence that partially accounts for the diversity of clinical presentations of patients with SCDS.

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.

Third Window Syndrome: Surgical Management of Cochlea-Facial Nerve Dehiscence

Objective: This communication is the first assessment of outcomes after surgical repair of cochlea-facial nerve dehiscence (CFD) in a series of patients. Pre- and post-operative quantitative measurement of validated survey instruments, symptoms, diagnostic findings and anonymous video descriptions of symptoms in a cohort of 16 patients with CFD and third window syndrome (TWS) symptoms were systematically studied. Study design: Observational analytic case-control study. Setting: Quaternary referral center. Patients: Group 1 had 8 patients (5 children and 3 adults) with CFD and TWS who underwent surgical management using a previously described round window reinforcement technique. Group 2 had 8 patients (2 children and 6 adults) with CFD who did not have surgical intervention. Interventions: The Dizziness Handicap Inventory (DHI) and Headache Impact Test (HIT-6) were administered pre-operatively and post-operatively. In addition, diagnostic findings of comprehensive audiometry, cervical vestibular evoked myogenic potential (cVEMP) thresholds and electrocochleography (ECoG) were studied. Symptoms before and after surgical intervention were compared. Main outcome measures: Pre- vs. post-operative DHI, HIT-6, and audiometric data were compared statistically. The thresholds and amplitudes for cVEMP in symptomatic ears, ears with cochlea-facial nerve dehiscence and ears without CFD were compared statistically. Results: There was a highly significant improvement in DHI and HIT-6 at pre- vs. post-operative (p < 0.0001 and p < 0.001, respectively). The age range was 12.8-52.9 years at the time of surgery (mean = 24.7 years). There were 6 females and 2 males. All 8 had a history of trauma before the onset of their symptoms. The mean cVEMP threshold was 75 dB nHL (SD 3.8) for the operated ear and 85.7 dB (SD 10.6) for the unoperated ear. In contrast to superior semicircular canal dehiscence, where most ears have abnormal ECoG findings suggestive of endolymphatic hydrops, only 1 of 8 operated CFD ears (1 of 16 ears) had an abnormal ECoG study. Conclusions: Overall there was a marked improvement in DHI, HIT-6 and symptoms post-operatively. Statistically significant reduction in cVEMP thresholds was observed in patients with radiographic evidence of CFD. Surgical management with round window reinforcement in patients with CFD was associated with improved symptoms and outcomes measures.

Reducing Radiation Dose for High-resolution Flat-panel CT Imaging of Superior Semicircular Canal Dehiscence

OBJECTIVE

High-resolution flat panel computed tomography (FPCT) is useful for the evaluation of temporal bone pathologies. While radiation exposure remains a concern, efforts have been devoted to reduce dose, while maintaining image quality. We hypothesize that removing the antiscatter grid (ASG) results in decreased radiation exposure, while maintaining diagnostic image quality for the evaluation of superior semicircular canal dehiscence (SSCD).

METHODS

Ten patients with clinical suspicion for SSCD participated in this prospective study. Two sequential collimated 20-second FPCT acquisitions were performed (first: grid in; second: grid removed) in all patients. Secondary reconstructions were created by manually generating the volume of interest to include the middle ear using a voxel size of 0.1 mm and 512 × 512 matrix. Radiation dose parameters (air kerma (Ka,r) in mGy and dose area product (DAP) in μGym) were recorded. Three reviewers analyzed images for the ability to diagnose SSCD, to identify the stapes crurae, and to determine if an ASG was present.

RESULTS

The average Ka,r and DAP for the grid-in acquisitions were 246.7 mGy (SD 47.9) and 2838.0 μGym (SD 862.8), versus 160.2 mGy (SD 33.2) and 2026.3 μGym (SD 644.8) for the grid-out acquisitions, respectively (p<0.001 for both Ka,r and DAP). Radiation exposure was reduced by approximately 30% solely by removing the ASG. All reviewers correctly identified all patients with SSCD (confirmed at surgery), with mean AUC of 0.99 (κ = 0.90).

CONCLUSION

Removing the antiscatter grid during FPCT imaging of the temporal bones is a simple and effective way to reduce radiation exposure while maintaining diagnostic image quality for the evaluation of SSCD.

Electrocochleography Results in Patients With Bilateral Vestibular Paresis and Sound- or Pressure-Induced Horizontal Nystagmus

OBJECTIVE

To describe the electrocochleography (ECochG) findings in patients with bilateral vestibular paresis and sound- and/or pressure-induced horizontal nystagmus.

DESIGN

Retrospective case series.

SETTING

Tertiary care center.

PATIENTS

Three adult patients with bilateral vestibular paresis and sound- and/or pressure-induced horizontal nystagmus were evaluated from 2012 to 2016.

MAIN OUTCOME MEASURE

All patients underwent ECochG, vestibular evoked myogenic potential (VEMP) testing, bithermal caloric testing, rotary chair testing, audiometric testing, and temporal bone computed tomography (CT). For ECochG, the summating potential (SP) to action potential (AP) ratio was determined.

RESULTS

All patients had normal temporal bone CT, reduced caloric responses bilaterally, decreased gain on rotary chair, and abnormal ECochG. For two subjects, the SP/AP was elevated bilaterally. One subject had unilateral SP/AP elevation. Cervical VEMPs were present in all subjects, but at reduced thresholds in two subjects.

CONCLUSION

SP/AP elevation was found in all three patients with the syndrome of bilateral vestibular paresis and/or sound- or pressure-induced horizontal nystagmus. As the etiology of this syndrome remains unclear, understanding the basis for abnormal ECochG may shed insight into the pathophysiology of this condition.

Audiometric and cVEMP Thresholds Show Little Correlation With Symptoms in Superior Semicircular Canal Dehiscence Syndrome

OBJECTIVE

Evaluate the relationship between objective audiometric and vestibular tests and patient symptoms in superior canal dehiscence (SCD) syndrome.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary care center.

PATIENTS

Ninety-eight patients with SCD, preoperative threshold audiograms, cervical vestibular evoked myogenic potential (cVEMP) thresholds, and computed tomography (CT) imaging were included. Clinical reports were reviewed for self-reported SCD symptoms. Twenty-five patients completed the Hearing Handicap Inventory (HHI), Dizziness Handicap Inventory (DHI), Autophony Index (AI), and the 36-item Short Form Survey (SF-36).

MAIN OUTCOME MEASURES

Correlations between preoperative low-frequency air-bone gap (ABG), cVEMP thresholds, and symptoms (including HHI, DHI, AI, and SF-36). Symptoms included hearing loss, aural fullness, autophony, hyperacusis, tinnitus, vertigo, imbalance and sound-, pressure and exercise provoked dizziness. Secondary outcome measure: Correlations between changes of objective and subjective measures before and after surgery.

RESULTS

Patients who reported hearing loss had larger ABGs at 250 Hz than patients without subjective hearing loss (p = 0.001). ABGs and cVEMP thresholds did not correlate with any other symptom. No significant correlation was found between ABG or cVEMP threshold and the HHI, DHI, AI or Health Utility Value (derived from the SF-36 quality of life score). Following SCD surgery, ABG decreased (p < 0.001), cVEMP thresholds increased (p < 0.001) and overall symptoms, handicap scores and quality-of-life improved; however, there was no significant relationship between these measures.

CONCLUSION

While threshold audiometry and cVEMP are important tools to diagnose SCD and monitor surgical outcomes, these measures showed no significant correlation with vestibular and most auditory symptoms or their severity.

Comparison of Transmastoid and Middle Fossa Approaches for Superior Canal Dehiscence Repair: A Multi-institutional Study

OBJECTIVE

To compare outcomes for patients undergoing a transmastoid approach versus a middle fossa craniotomy approach with plugging and/or resurfacing for repair of superior semicircular canal dehiscence. Outcome measures include symptom resolution, hearing, operative time, hospital stay, complications, and revision rates.

STUDY DESIGN

Multicenter retrospective comparative cohort study.

SETTINGS

Three tertiary neurotology centers.

SUBJECTS AND METHODS

All adult patients undergoing repair for superior canal dehiscence between 2006 and 2017 at 3 neurotology centers were included. Demographics and otologic history collected by chart review. Imaging, audiometric data, and vestibular evoked myogenic potential measurements were also collected for analysis.

RESULTS

A total of 68 patients (74 ears) were included in the study. Twenty-one patients underwent middle fossa craniotomy repair (mean age, 47.9 years), and 47 underwent transmastoid repair (mean age, 48.0 years). There were no significant differences in age or sex distribution between the groups. The transmastoid group experienced a significantly shorter duration of hospitalization and lower recurrence rate as compared with the middle fossa craniotomy group (3.8% vs 33%). Both groups experienced improvement in noise-induced vertigo, autophony, pulsatile tinnitus, and nonspecific vertigo. There was no significant difference among symptom resolution between groups. Additionally, there was no significant difference in audiometric outcomes between the groups.

CONCLUSION

Both the transmastoid approach and the middle fossa craniotomy approach for repair of superior canal dehiscence offer symptom resolution with minimal risk. The transmastoid approach was associated with shorter hospital stays and lower recurrence rate as compared with the middle fossa craniotomy approach.

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.

The Gopen-Yang Superior Semicircular Canal Dehiscence Questionnaire: development and validation of a clinical questionnaire to assess subjective symptoms in patients undergoing surgical repair of superior semicircular canal dehiscence

OBJECTIVE

To characterise subjective symptoms in patients undergoing surgical repair of superior semicircular canal dehiscence.

METHODS

Questionnaires assessing symptom severity and impact on function and quality of life were administered to patients before superior semicircular canal dehiscence surgery, between June 2011 and March 2016. Questionnaire sections included general quality of life, internal amplified sounds, dizziness and tinnitus, with scores of 0-100 points.

RESULTS

Twenty-three patients completed the questionnaire before surgery. Section scores (mean±standard deviation) were: 38.2 ± 25.2 for general quality of life, 52.5 ± 23.9 for internal amplified sounds, 35.1 ± 28.8 for dizziness, 33.3 ± 30.7 for tinnitus, and 39.8 ± 22.2 for the composite score. Cronbach's α statistic averaged 0.93 (range, 0.84-0.97) across section scores, and 0.83 for the composite score.

CONCLUSION

The Gopen-Yang Superior Semicircular Canal Dehiscence Questionnaire provides a holistic, patient-centred characterisation of superior semicircular canal dehiscence symptoms. Internal consistency analysis validated the questionnaire and provided a quantitative framework for further optimisation in the clinical setting.

Can Wideband Tympanometry Be Used as a Screening Test for Superior Semicircular Canal Dehiscence?

OBJECTIVES

We explored whether wideband tympanometry (WBT) could be used as a screening test for superior semicircular canal dehiscence (SSCD), and obtained new WBT data (given that the test is not yet in common clinical use) on patients with SSCD.

METHODS

We compared the WBT data of patients clinically and radiologically diagnosed with SSCD in our hospital between 2013 and 2018 to those of healthy volunteers. We compared the resonance frequency (RF), maximum absorbance frequency (MAF), and maximum absorbance ratio (MAR). The t-test was used for statistical analysis with the significance level set to P<0.05. In addition, we used receiver operating characteristic analysis to derive cutoff values for SSCD diagnosis in terms of sensitivity and specificity.

RESULTS

Seventeen patients (four with bilateral and 13 with unilateral disease; 17 ears) diagnosed with SSCD and 27 healthy volunteers (47 ears) were included. The mean RFs of the SSCD patients and healthy subjects were 548.7 Hz (range, 243 to 853 Hz) and 935.1 Hz (range, 239 to 1,875 Hz), respectively (P<0.001). The mean MARs of the SSCD patients and healthy subjects were 89.4% (range, 62% to 100%) and 82.4% (range, 63% to 99%), respectively (P=0.005). The mean MAFs of the SSCD patients and healthy subjects were 1,706.3 Hz (range, 613 to 3,816 Hz) and 2,668 Hz (range, 876 to 4,387 Hz), respectively (P<0.001). In terms of SSCD diagnosis, a MAR above 86% afforded 81% sensitivity and 77% specificity; an RF below 728 Hz, 86% sensitivity and 81% specificity; and an MAF below 1,835 Hz, 79% sensitivity and 67% specificity.

CONCLUSION

WBT may be a useful clinical screening test for SSCD. The RF and MAF were lower, and the MAR higher, in SSCD patients than in normal controls.

Anterior Canal benign paroxysmal positional Vertigo following surgical Management of superior canal dehiscence

OBJECTIVE

Benign paroxysmal positional vertigo (BPPV) is a common post-surgical finding in patients managed for superior semicircular canal dehiscence (SSCD). The posterior semicircular canal has been reported as the involved canal in the majority of cases of post-surgical BPPV, with only two cases reported of lateral canal involvement. The objective of this report is to present a case in which an anterior semicircular canal BPPV response was identified in a patient following surgical management for SSCD.

METHOD

This case report presents an adult with residual dizziness following surgical management of SSCD and vestibular rehabilitation therapy (VRT). During subsequent evaluation of vestibular function, a transient and torsional, down-beating nystagmus was provoked along with vertigo during Dix-Hallpike positioning to the right. This was consistent with BPPV affecting the left superior (anterior) semicircular canal.

RESULTS

The patient was treated with a repositioning maneuver to manage anterior semicircular canal BPPV and no nystagmus response was recorded with post-repositioning Dix-Hallpike test. Review of radiographic images, obtained prior to vestibular function testing, showed a hyperintensity in the area of the left anterior semicircular canal ampulla. It was felt this was likely a bone chip from the SSCD repair that was pushing against the ampulla with further mobile debris within the canal.

CONCLUSION

It is reported that BPPV is a common complication in patients surgically managed for SSCD. Posterior semicircular canal BPPV is reported most often, with a couple of cases of lateral semicircular canal BPPV also reported. As far as we are aware, the current case represents the first report of anterior semicircular canal BPPV in this type of patient.

Postoperative MR imaging features after superior semicircular canal plugging in Minor syndrome

PURPOSE

To report the postoperative magnetic resonance imaging (MRI) features after superior semicircular canal plugging in patients with Minor syndrome.

MATERIALS AND METHODS

The MRI examinations with 3D T2-weighted SPACE sequence of 12 patients with superior semicircular canal dehiscence syndrome (SCDS) were retrospectively assessed. Two radiologists independently evaluated the presence of a filling defect of the superior semicircular canal above the superior ampulla and the common crus using an oblique plane parallel to the superior semicircular canal (Pöschl's plane).

RESULTS

Postoperative MRI showed a filling defect above the ampulla of the superior semicircular canal and the common crus in 8/12 patients (67%). Three patients (3/12; 25%) had a filling defect involving also the superior ampulla that caused postoperative labyrinthitis with labyrinthine enhancement on MRI in 2 patients. One patient (1/12; 8%) had incomplete plugging of superior semicircular canal with abnormal functional tests and remaining symptoms.

CONCLUSION

Postoperative MRI shows a normal plugging aspect of the superior semicircular canal in 67% of patients. MRI can reveal complications that may have therapeutic implications.

Cross Sectional Imaging of the Ear and Temporal Bone

CT and MR imaging are essential cross-sectional imaging modalities for assessment of temporal bone anatomy and pathology. The choice of CT versus MR depends on the structures and the disease processes that require assessment, delineation, and characterization. A thorough knowledge of the two imaging modalities' capabilities and of temporal bone anatomy greatly facilitates imaging interpretation of pathologic conditions.