Asymptomatic superior semicircular canal dehiscence.

OBJECTIVE: To describe a case of asymptomatic superior semicircular canal dehiscence. METHOD: Clinical case report. RESULTS: A 50-year-old man presenting with right-sided Ménière´s disease also showed an enhanced response on vestibular evoked myogenic potential testing for the left ear. Unilateral left-sided superior semicircular canal bone dehiscence was clearly visualised on a subsequent temporal bone computed tomography scan. These findings were consistent with superior canal dehiscence syndrome. However, the patient did not complain of any specific superior canal dehiscence syndrome symptoms. Given that vestibular evoked myogenic potential testing may detect asymptomatic forms of superior canal dehiscence, as noted in this case, such testing seems to exhibit reduced specificity for superior canal dehiscence syndrome. CONCLUSION: An enhanced response on vestibular evoked myogenic potential testing in isolation appears to be a weaker indicator of superior canal dehiscence syndrome, and rather a marker of superior semicircular canal dehiscence.

Superior Semicircular Canal Dehiscence Syndrome Following Head Trauma: A Multi-institutional Review.

OBJECTIVE: To evaluate patients who become symptomatic from superior semicircular canal dehiscence (SSCD) following head trauma. STUDY DESIGN: Case series assessing patients presenting with SSCD after a trauma. METHODS: A case series was completed assessing patients presenting with SSCD after trauma. Data from three academic medical centers were evaluated, including the following: imaging, videonystagmography (VNG)/vestibular evoked myogenic potential (VEMP) testing, audiometric assessment, and surgical repair. Outcome measures included the following: 1) Description of audio-vestibular symptoms, 2) mean pre- and post-operative pure tone average (PTA), word recognition score (WRS), and air bone gap (ABG). RESULTS: A total of 14 patients were included; 86% were male. Approximately 43% were found to have bilateral SSCD on imaging, with 57% of patients pursuing surgical management. The most common presenting symptoms included pulsatile tinnitus (93%), autophony (79%), and hearing loss (64%). Approximately 36% of patients underwent VNG/VEMP testing, with 83.3% of those demonstrating abnormal results. The mean audiometric findings on the symptomatic side included an air-conduction PTA of 38.0 dB, bone-conduction PTA of 24.3 dB, WRS of 81%, and ABG of 17.9 dB. Among patients who underwent surgery (57%), there was no significant change in the air-conduction PTA, bone-conduction PTA, or WRS (P > .05). However, there was an improvement in the ABG (preoperative = 22.8 dB versus postoperative = 9.7 dB; P = .005). CONCLUSION: Head trauma may be a potentiating event for SSCD syndrome. This study advances the hypothesis that these patients likely have underlying radiographic SSCD prior to their trauma, and a traumatic event increases in intra-vestibular or intracranial pressures, unmasking SSCD syndrome. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E2810-E2818, 2021.

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.

Video-head impulse test in superior canal dehiscence.

BACKGROUND: Superior Canal Dehiscence is classically diagnosed with typical abnormalities on Vestibular Evoked Myogenic Potentials (VEMPs) and Computed Tomography (CT) scans. AIM: This paper discusses the utility of the video Head Impulse Test (vHIT) in SCD. METHODS: Data from 11 ears (8 patients) with SCD were retrospectively reviewed. Results from vHIT, VEMPs and CT and when possible, MRI scans were correlated. An audit of 300 vHIT from patients undergoing routine testing for any neurotological complaint was also conducted to look at the incidence of isolated abnormal superior canal function. RESULTS: 82% of patients (9 ears) with SCD showed abnormal vHIT (reduced gain and catch-up saccades) isolated to the affected superior semicircular canal. CONCLUSION: Correlation of the CT and VEMPs are important in forming a diagnosis of SCD. However, if isolated superior canal vHIT abnormalities are demonstrated, it is suggestive of SCD and such patients should be referred for further investigations.

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.

Elevated ocular VEMP responses in the absence of a superior semicircular canal dehiscence.

BACKGROUND: Vestibular evoked myogenic potentials (VEMPs) have an accepted role in the diagnosis of the superior semicircular canal dehiscence (SSCD) syndrome. The current impression is that ocular VEMPs (oVEMPs) are more sensitive than cervical VEMPs (cVEMPs) for detecting a SSCD and that oVEMP testing in response to air conducted sound provides an excellent screening test without risk of radiation exposure from computerized tomography (CT). AIMS/OBJECTIVES: To report on patients with elevated oVEMP amplitudes but without evidence for a SSCD on multiplanar CT imaging. MATERIAL AND METHODS: Retrospective chart review of all patients referred for vestibular function testing to our department. Patients with oVEMP peak-to-peak amplitudes ≥17 µν without evidence for a SSCD on imaging were evaluated. RESULTS: 26 patients had oVEMP peak-to-peak amplitudes ≥17 µν with no evidence of a SSCD on imaging. The most common diagnosis was Meniere's disease in those identified. CONCLUSION AND SIGNIFICANCE: oVEMPs can provide false positive results for diagnosis of a SSCD and an elevated oVEMP amplitude in itself is insufficient for diagnosis of a SSCD.

Current management of superior semicircular canal dehiscence syndrome.

PURPOSE OF REVIEW: The current article reviews literature on the contemporary management of superior semicircular canal dehiscence syndrome (SSCDS). Approaches to management and surgical techniques are compared along with a discussion of the use of more standardized, objective outcome measures. RECENT FINDINGS: Considerable debate still exists as to what approach and technique is most appropriate for patients with SSCDS and how to best measure postoperative outcomes. However, it is increasingly accepted that multiple factors account for outcomes in SSCDS, including presenting symptoms and presence of vestibular comorbidities. Therefore, surgical intervention is best tailored to each individual patient. Data on SSCDS outcomes is heterogenous, and increased emphasis is being placed on validated measures of outcome. Round window approaches remain controversial and their role is still undefined. SUMMARY: The treatment strategies for SSCDS continue to diversify. A patient-specific approach with systematic documentation of outcomes will continue to inform how these patients are best managed.

Multiple Co-Occurring Vestibular Disorders Identified Using the Dizziness Symptom Profile.

Purpose The purpose of the current investigation was to determine the interrelations among vestibular disorders from a data set generated from the patient perspective as compared to previous data generated from the physician's perspective. Method The data for the current investigation originated from a previously published study describing the development of the Dizziness Symptom Profile (DSP; Jacobson et al., 2019). The DSP is a 31-item patient self-report tool designed to help primary care physicians in the development of a differential diagnosis using the patient's level of agreement with each dizziness and symptom-related statement. Responses to these items converge on common vestibular diagnoses and were previously found to agree with ear specialist differential diagnoses 70.3% of the time. Data were collected for 131 subjects (M age = 56.7 years, 72 women) seen for evaluation in a tertiary dizziness specialty clinic. For this study, the data were analyzed using descriptive statistics to determine the frequency of single diagnoses, multiple diagnoses, co-occurring diagnoses, and patterns of co-occurrence. Results Results indicated that 52.7% of patients endorsed a single vestibular diagnosis and 47.3% endorsed two or more vestibular diagnoses. Benign paroxysmal positional vertigo (BPPV) and vestibular migraine were the most common single diagnoses and also the most common co-occurring diagnoses. As the number of diagnoses endorsed on the DSP increased, so did the percentage of time that BPPV and vestibular migraine would occur. Conclusions Results support and extend the work of others but using data generated from the perspective of the patient. A slight majority of patients endorsed a single disorder, but almost as many patients endorsed more than one vestibular diagnosis. BPPV and vestibular migraine were the most common single vestibular diagnoses and also the most common co-occurring vestibular diagnoses; vestibular migraine was more common when multiple diagnoses were endorsed. Results suggest it is common for patients to volunteer symptoms that cannot be explained by a single vestibular diagnosis. This finding is in agreement with physician-generated diagnosis data. Clinicians should consider the possibility of co-occurring diagnoses in complicated patients or in patients who are not responding optimally to management of a single vestibular disorder. The DSP is a tool that encourages clinicians to consider multiple co-occurring vestibular disorders as the source of patient complaints.

Superior Semicircular Canal Dehiscence Syndrome.

Superior canal dehiscence syndrome (SCDS) is a vestibular disorder caused by a pathologic third window into the labyrinth that can present with autophony, sound- or pressure-induced vertigo, and chronic disequilibrium among other vestibulocochlear symptoms. Careful history taking and examination in conjunction with appropriate diagnostic testing can accurately diagnose the syndrome. Key examination techniques include fixation-suppressed ocular motor examination investigating for sound- or pressure-induced eye movements in the plane of the semicircular canal. Audiometry, vestibular evoked myogenic potentials, and computed tomography confirm the diagnosis. Corrective surgical techniques can be curative, but many patients find their symptoms are not severe enough to undergo surgery. Although a primarily peripheral vestibular disorder, as first-line consultants for most dizziness complaints, neurologists will serve their patients well by understanding SCDS and its role in the differential diagnosis of vestibular disorders.

Symptoms, Audiometric and Vestibular Laboratory Findings, and Imaging in a Concurrent Superior Canal Dehiscence Syndrome and Vestibular Schwannoma: A Case Report.

BACKGROUND: Dizziness is a common complaint that can arise from multiple systems in the body. Objective vestibular tests are used to understand the underlying function of the vestibular system and whether or not it may be contributing to the dizziness symptoms experienced by the patient. Even when comprehensive case history is consistent with an otologic etiology, audiometric and vestibular tests are ordered to objectively characterize inner ear function to help further refine the differential diagnoses and aid in guiding treatment options. Few reports in the literature describe audiometric and vestibular results in patients with multiple concurrent otologic etiologies. PURPOSE: This case provides a description of audiometric, vestibular, and imaging results in a case of concurrent bilateral superior canal dehiscence, right-sided vestibular schwannoma, and right-sided posterior canal benign paroxysmal positional vertigo. The patient's symptoms and laboratory findings are described in detail and, where appropriate, highlight challenges that may arise in interpretation. RESEARCH DESIGN: A case report. RESULTS: The patient presented for evaluation of dizziness, asymmetric hearing loss, and autophony. Comprehensive audiometric evaluation shows asymmetric sensorineural hearing loss and an air-bone gap at 250 Hz in the right ear. Vestibular evaluation shows right caloric asymmetry along with abnormal cervical vestibular- and ocular vestibular-evoked myogenic potentials, with the left ear showing results consistent with the third-window pathology. CONCLUSIONS: Comprehensive assessment of symptoms and critical thinking while performing testing are necessary when examining multiple concurrent otologic etiologies in a patient. Knowledge of anticipated test results and physiology may help the audiologist to synthesize results and make appropriate clinical recommendations as part of the multidisciplinary team.

Cautionary Findings for the Presence of Facial Canal Dehiscence During Cholesteatoma Surgery.

Our aim was to investigate the relationship between facial canal dehiscence (FCD) and surgical findings and procedures in patients with cholesteatoma. A total of 186 patients (118 males, 39.2 ± 15 years) who underwent surgery for advanced cholesteatoma between 2013 and 2018 were included in the study. The relationship between FCD and surgical findings was investigated via the surgical registries. The prevalence of FCD was 36.6% (68/186). The prevalence of FCD was 44%, and 13.2% for the patients who underwent canal wall down mastoidectomy (62/141) and canal wall up mastoidectomy (6/45), respectively (P < .001). Facial canal dehiscence was detected in 73.9% of the 23 patients who had a lateral semicircular canal (LSCC) defect (P < .001), in 61.9% of 21 patients who had a tegmen tympani defect, and in 58.1% of the 31 patients who had erosion on the posterior wall of the external auditory canal (EAC; P < .05). The prevalence of FCD was 3.1% in patients with isolated incus erosion, 59.1% in patients with erosion of malleus and incus, 60.7% in patients with erosion of stapes suprastructure and incus, and 43.2% in patients with whole ossicular chain deformation (P < .001). The defects on LSCC, EAC, tegmen tympani, and malleus and incus might be cautionary findings for the presence of FCD during cholesteatoma surgery.