Cervical and Ocular VEMP Testing in Diagnosing Superior Semicircular Canal Dehiscence

Diagnostic Yield of Patients Undergoing Evaluation of Possible Superior Canal Dehiscence

OBJECTIVE

To characterize the diagnostic yield of patients undergoing evaluation for superior canal dehiscence syndrome (SCDS), and identify alternative conditions diagnosed in patients suspected of, but not ultimately diagnosed with, SCDS.

METHODS

Diagnostically undifferentiated adult patients suspected of having SCDS were identified between 2016 and 2021 at a tertiary academic medical system. Patients were categorized by diagnostic testing, radiographic superior semicircular canal (SSC) abnormality, symptoms, evaluating clinician specialty, operative intervention, and diagnosis. Differences among groups were assessed for statistical significance.

RESULTS

Of 1242 candidate patients, 477 met inclusion criteria-evaluation by a clinician with SCDS on their differential diagnosis prior to diagnostic imaging. The mean (SD) age was 53.0 (15.0) years and 70.6% were female. A total of 364 patients underwent subsequent diagnostic imaging, and among these, 164 (45.1%) had a radiographic SSC abnormality with 99 (27.2%) receiving a diagnosis of SCDS (two cases of "near dehiscence syndrome"). One third (33.3%) of patients with SCDS underwent operative repair. Most clinicians with the initial suspicion for SCDS were otolaryngologists (90.6%), who had greater diagnostic yield than clinicians from other specialties (22.2% vs. 6.7%, p = 0.012). Patients not diagnosed with SCDS alternatively received 21 unique diagnoses and 52.1% (138/265) were not definitively diagnosed with any condition.

CONCLUSIONS

This study characterizes the diagnostic incidence, or yield, of newly identified radiographic SSC abnormalities (45.1%) and SCDS (27.2%) among people suspected of having SCDS. Considerable overlap in presentation between SCDS and other conditions exists, and there is need for improvement in efficiently diagnosing patients with SCDS and audio-vestibular complaints in general.

LEVEL OF EVIDENCE

III Laryngoscope, 2024.

Predictors of non-primary auditory and vestibular symptom persistence following surgical repair of superior canal dehiscence syndrome

Objective

Patients with superior canal dehiscence syndrome (SCDS) can present with a plethora of auditory and/or vestibular symptoms associated with a bony defect of the superior semicircular canal. While surgical repair is a reasonable option for patients with significant localizing symptoms, the degree of clinical improvement will vary among patients and poses challenges in outcome prediction. This study aims to assess the relationship between preoperative and postoperative symptoms and identify predictors of symptom persistence following repair.

Study design

Retrospective chart review.

Setting

Tertiary neurotology single-institution care center.

Main outcome measures

The primary outcome was to determine the proportion of resolved and persistent primary (most bothersome) and non-primary audiologic and vestibular symptoms following SCD repair. Secondary outcomes included comparison of patient, operative and radiologic characteristics between patients with resolved vs. persistent symptoms. Standardized patient questionnaires including 11 auditory and 8 vestibular symptoms were administered to patients at their preoperative and follow-up visits. Patient pre- vs. postoperative survey results, demographic and clinical characteristics, operative characteristics, audiometric data and cervical vestibular evoked myogenic potential (cVEMP) thresholds were compared via univariate χ2 and multivariate binary logistic regression analyses between those patients reporting full postoperative resolution of symptoms and persistence of one or more symptoms. Radiologic computed tomography (CT) measurements of superior canal dehiscence (SCD) defect size, location, and laterality were also compared between these two groups.

Results

Of 126 patients (132 ears) included in our study, 119 patients (90.2%) reported postoperative resolution (n = 82, 62.1%) or improvement (n = 37, 28.0%) of primary (most bothersome) symptoms, while 13 patients (9.8%) reported persistence of primary symptoms. The median (interquartile range) and range between surgery and questionnaire completion were 9 (4-28), 1-124 months, respectively. Analyzing all symptoms (primary and non-primary) 69 (52.3%) and 68 (51.1%) patients reported complete postoperative auditory and vestibular symptom resolution, respectively. The most likely persistent symptoms included imbalance (33/65/67, 50.8%), positional dizziness (7/20, 35.0%) and oscillopsia (44/15, 26.7%). Factors associated with persistent auditory symptoms included history of seizures (0% vs. 7.6%, p = 0.023), auditory chief complaint (50.0% vs. 70.5%), higher PTA (mean 19.6 vs. 25.1 dB, p = 0.043) and higher cervical vestibular evoked myogenic potential (cVEMP) thresholds at 1000 Hz (mean 66.5 vs. 71.4, p = 0.033). A migraine diagnosis (14.0% vs. 41.9% p < 0.010), bilateral radiologic SCD (17.5% vs. 38.1%, p = 0.034) and revision cases (0.0% vs. 14.0%, p = 0.002) were associated with persistent vestibular symptoms. Neither SCD defect size nor location were significantly associated with symptom persistence (P > 0.05).

Conclusions

Surgical repair for SCDS offers meaningful reduction in the majority of auditory and vestibular symptoms. However, the persistence of certain, mostly non-primary, symptoms and the identification of potential associated factors including migraines, PTA thresholds, cVEMP threshold, bilateral SCD, and revision cases emphasize the importance of individualized patient counseling and management strategies.

Superior canal dehiscence syndrome: A review

Superior canal dehiscence syndrome (SCDS) is a vestibular disorder in which the presence of a pathological third window in the labyrinth causes several vestibular and cochlear symptoms. Herein, we review the diagnostic criteria and treatment of SCDS. The cause of SCDS is considered to be congenital or acquired; however, its etiology is not well known. Symptoms: Vertigo and/or oscillopsia induced by loud sounds (Tullio phenomenon) or stimuli that change the middle ear or intracranial pressure (fistula symptoms) with vestibular symptoms and hyperacusis and aural fullness with cochlear symptoms are characteristic clinical complaints of this syndrome. Neurological tests: Vertical-torsional eye movements can be observed when the Tullio phenomenon or fistula symptoms are induced. Conductive hearing loss with both a decrease in the bone conduction threshold at lower frequencies and an increase in the air conduction threshold at lower frequencies may be present on audiometry. Cervical and/or ocular vestibular evoked myogenic potentials are effective in strongly suspecting the presence of a pathologic third window in the labyrinth. Computed tomography (CT) imaging: High-resolution CT findings with multiplanar reconstruction in the plane of the superior semicircular canal consistent with dehiscence indicate SCDS. The Pöschl view along the plane of the superior semicircular canal and the Stenvers view perpendicular to it are recommended as CT imaging conditions. Findings from all three major diagnostic categories (symptoms, neurological tests, and/or CT imaging) are needed to diagnose SCDS. The surgical approaches for SCDS are as follows: the 1) middle cranial fossa approach, 2) transmastoid approach, and 3) round window and oval window reinforcement. Each technique has advantages and disadvantages.

Electrocochleography in the diagnosis of third window conditions

Introduction

Superior semicircular canal dehiscence (SSCD) is the best-known and most common presentation of so-called "third window conditions." There are a variety of diagnostic measures and tests for this condition in the current literature, including air-bone gap, vestibular-evoked myogenic potentials, and electrocochleography (EcochG). The purpose of this study was to investigate the diagnostic utility of EcochG and its relationship to air-bone gap in a cohort of patients with confirmed SSCD.

Methods

We reviewed data from 20 patients (11 female and 9 male subjects, age ranging 21-78 years), with confirmed unilateral or bilateral superior canal dehiscence. In total, 11 patients had unilateral SSCD and 9 patients had bilateral SSCD as determined by high-resolution CT scan. This resulted in the inclusion of twenty-nine ears with superior canal dehiscence and 11 normal ears.

Results

Our results indicated that all confirmed SSCD ears presented with an abnormal EcochG SP/AP value and that there was a statistically significant difference between normal and dehiscent ears. There was no statistically significant relationship between air-bone gap and SP/AP ratio in the ears diagnosed with SSCD nor was there a significant difference between dehiscent and normal ears in terms of air-bone gap at three frequencies.

Discussion

These results are consistent with previous studies showing the diagnostic utility of EcochG for this condition and the variability of air-bone gap. While an unexpected air-bone gap continues to be a red flag for SSCD, its absence along with the presence of subjective symptoms is a reasonable indicator for further clinical investigation to include EcochG.

Measurement of Ocular Vestibular Evoked Myogenic Potentials: Nasion Reference Montage as an Alternative to the Clinical Standard Montage

OBJECTIVE

To compare two novel electrode montages for ocular, vestibular evoked myogenic potential using single-nasion reference electrodes with the clinical standard montage.

STUDY DESIGN

Randomized crossover experiment.

SETTING

Tertiary referral center.

PARTICIPANTS

Sixty healthy participants.

INTERVENTION

Normal hearing and vestibular function were confirmed with an extensive test-battery. All ocular, vestibular evoked myogenic potential settings were measured with air-conducted tone bursts at 100-dB normal hearing level and a frequency of 500 Hz. Three electrode montages were measured in randomized order: the clinical standard montage ("S"), the nasion reference montage ("N"), and the nasion reference montage with a more lateral active electrode ("L"). Upgaze was standardized to 35 degrees.

MAIN OUTCOME MEASURES

Detection rate, latency of N1 and P1, peak-to-peak amplitude of N1 and P1, signal-to-noise ratio (SNR), asymmetry ratio (AR), concordance of expert assessment, and reliability.

RESULTS

All electrode montages showed detection rates greater than 90%. Latencies for "L" were shorter than for "S" and "N." Amplitudes and SNR for "S" and "N" were higher than for "L," whereas the values for "S" and "N" did not differ significantly. For AR, no significant differences between the montages were assessed. Concordance of experts ranged from 78% for "L" and 89.8% for "N." All montages provided excellent day-to-day reliability (intraclass correlation coefficient ≥0.9) for amplitudes and SNR.

CONCLUSIONS

Montage N could be a useful alternative to the clinical standard montage: although results are roughly equivalent, montage N requires one less electrode to do so.

Vestibular mapping in Ramsay-Hunt syndrome and idiopathic sudden sensorineural hearing loss

PURPOSE

To observe vestibular impairment patterns in patients with Ramsay Hunt syndrome with dizziness (RHS_D) and sudden sensorineural hearing loss with dizziness (SSNHL_D) using hierarchical cluster analysis (HCA) to interpret results with possible mechanisms.

METHODS

The data of 30 RHS_D and 81 SSNHL_D patients from January 2017 to August 2022 in a single tertiary referral center were retrospectively analyzed. Video head impulse test (vHIT) and vestibular evoked myogenic potential (VEMP) were used for vestibular analysis of peripheral vestibular organs, and the results of vHIT and VEMP were analyzed. HCA was used to analyze vestibular impairment patterns.

RESULTS

In RHS_D patients, the lateral semicircular canal (LSCC) was the most impaired semicircular canal (SCC), followed by the anterior semicircular canal (ASCC) and the posterior semicircular canal (PSCC), and the utricle was more impaired than the saccule. In SSNHL_D patients, the PSCC was the most impaired SCC, followed by the LSCC and the ASCC, and the utricle was more impaired than the saccule. In HCA of RHS_D patients, the ASCC and utricle were initially clustered, followed by the LSCC, PSCC and saccule in order. In the HCA of SSNHL_D patients, the PSCC was solely merged and independently clustered.

CONCLUSION

There were different patterns of vestibular impairments between RHS_D and SSNHL_D patients. The vestibular analysis and HCA results of SSNHL_D showed tendency of skip lesion, which could be explained by vascular pathophysiology.

A Comparative Study Using Vestibular Mapping in Sudden Sensorineural Hearing Loss With and Without Vertigo

OBJECTIVE

To investigate the impairment patterns in peripheral vestibular organs in sudden sensorineural hearing loss (SSNHL) with and without vertigo.

STUDY DESIGN

Retrospective study.

SETTING

Single tertiary medical center.

METHODS

Data from 165 SSNHL patients in a tertiary referral center from January 2017 to December 2022 were retrospectively analyzed. All patients underwent a video head impulse test, vestibular evoked myogenic potential test, and pure-tone audiometry. Hierarchical cluster analysis was performed to investigate vestibular impairment patterns. The prognosis of the hearing was determined using American Academy of Otolaryngology-Head and Neck Surgery recommendations.

RESULTS

After excluding patients with vestibular schwannoma and Meniere's disease, 152 patients were included in this study. A total of 73 of 152 patients were categorized as SSNHL with vertigo (SSNHL_V) and showed an independent merge of the posterior semicircular canal (PSCC) in cluster analysis. A total of 79 of 152 patients were categorized as SSNHL without vertigo (SSNHL_N) and showed an independent merge of saccule in cluster analysis. The PSCC (56.2%) and saccule (20.3%) were the most frequently impaired vestibular organs in SSNHL_V and SSNHL_N, respectively. In terms of prognosis, 106 of 152 patients had partial/no recovery and showed an independent merge of the PSCC in cluster analysis. A total of 46 of 152 patients had a complete recovery and showed an independent merge of the saccule in cluster analysis.

CONCLUSION

A tendency of isolated PSCC dysfunction was seen in SSNHL_V and partial/no recovery. A tendency of isolated saccular dysfunction was seen in SSNHL_N and complete recovery. Different treatments might be needed in SSNHL depending on the presence of vertigo.

An evidenced-based diagnostic tool for superior semicircular canal dehiscence syndrome

Purpose

To construct a symptoms-based prediction tool to assess the likelihood of superior canal dehiscence (SSCD) on high-resolution CT.

Materials and methods

Mathematical modeling was employed to predict radiologic evidence of SSCD at a tertiary neurotology referral center.

Results

A total of 168 patients were included, of which 118 had imaging-confirmed SSCD. On univariate analysis significant predictors of SSCD presence were: sound/pressure-induced vertigo (p = 0.006), disequilibrium (p = 0.008), hyperacusis (p = 0.008), and autophony (p = 0.034). Multivariate analysis enabled a 14-point symptom-weighted tool to be developed, wherein a score of ≥6 raised the suspicion of SSCD (≥70% likelihood of being present), R2 = 0.853.

Conclusions

The likelihood of SSCD on CT scan can be determined with a high degree of certainty based on symptoms recorded at presentation. Using the evidenced-based diagnostic tool validated herein, a score ≥6 with any symptom combination justifies ordering a CT scan.

New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder

Background

Third window syndrome is a vestibular-cochlear disorder in humans in which a third mobile window of the otic capsule creates changes to the flow of sound pressure energy through the perilymph/endolymph. The nature and location of this third mobile window can occur at many different sites (or multiple sites); however, the most common third mobile window is superior semicircular canal dehiscence (SSCD). There are two essential objective diagnostic characteristics needed to validate a model of SSCD: the creation of a pseudoconductive hearing loss and cVEMP increased amplitude and decreased threshold.

Methods

Adult Mongolian gerbils (n = 36) received surgical fenestration of the superior semicircular canal of the left inner ear. ABR and c+VEMP testing were carried out prior to surgery and over acute (small 1 mm SSCD, 1-10 days) or prolonged (large 2 mm SSCD, 28 days) recovery. Because recovery of function occurred quickly, condenser brightfield stereomicroscopic examination of the dehiscence site was carried out for the small SSCD animals post-hoc and compared to both ABRs and c+VEMPs. Micro-CT analysis was also completed with representative samples of control, day 3 and 10 post-SSCD animals.

Results

The SSCD created a significant worsening of hearing thresholds of the left ear; especially in the lower frequency domain (1-4 kHz). Left (EXP)/right (CTL) ear comparisons via ABR show significant worsening thresholds at the same frequency representations, which is a proxy for the human pseudoconductive hearing loss seen in SSCD. For the c+VEMP measurements, increased amplitude of the sound-induced response (N1 2.5 ms and P1 3.2 ms) was observed in animals that received larger fenestrations. As the bone regrew, the c+VEMP and ABR responses returned toward preoperative values. For small SSCD animals, micro-CT data show that progressive osteoneogenesis results in resurfacing of the SSCD without bony obliteration.

Conclusion

The large (2 mm) SSCD used in our gerbil model results in similar electrophysiologic findings observed in patients with SSCD. The changes observed also reverse and return to baseline as the SSCD heals by bone resurfacing (with the lumen intact). Hence, this model does not require a second surgical procedure to plug the SSCD.

Usefulness of Cervical Vestibular-Evoked Myogenic Potentials for Diagnosing Patients With Superior Canal Dehiscence Syndrome: A Meta-Analysis

OBJECTIVES

To compare the diagnostic accuracy of cervical vestibular-evoked myogenic potential (cVEMP) for detecting superior canal dehiscence (SCD) syndrome to that of computed tomography (CT) and surgical findings.

DATABASES REVIEWED

PubMed, SCOPUS, Embase, Web of Science, and the Cochrane database.

METHODS

Databases were searched up to July 2021. True positives, true negatives, false positives, and false negatives were extracted. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool.

RESULTS

Our search yielded nine studies with 721 patients. Including all cVEMP thresholds, the diagnostic odds ratio (DOR) was 32.8483 (95% confidence interval [CI]: 19.6577, 54.8900; I2 = 49.9%). The area under the summary receiver operating characteristic curve (AUC) was 0.879. Sensitivity and specificity were 0.8278 (95% CI: 0.7517, 0.8842; I2 = 76.4%) and 0.8824 (95% CI: 0.7859, 0.9387; I2 = 92.8%), respectively. However, there was a high degree of heterogeneity (I2 ≥ 70%) due to the different VEMP threshold values used among the studies. In subgroup analysis, higher cVEMP threshold values showed higher sensitivity (threshold ≤ 85: 0.9568; threshold ≤ 65: 0.7691) but lower specificity (threshold ≤ 85: 0.5879; threshold ≤ 65: 0.8913). The threshold ≤75 subgroup showed moderate sensitivity of 0.7455, high specificity of 0.9526, and the highest DOR of 38.9062. The AUC of this subgroup was 0.894.

CONCLUSIONS

cVEMP is a reliable adjunctive tool for the clinical diagnosis of SCD. Taking the balance between sensitivity and specificity into consideration, a cVEMP threshold value of 75 showed good diagnostic accuracy.

Machine Learning Techniques for Differential Diagnosis of Vertigo and Dizziness: A Review

Vertigo is a sensation of movement that results from disorders of the inner ear balance organs and their central connections, with aetiologies that are often benign and sometimes serious. An individual who develops vertigo can be effectively treated only after a correct diagnosis of the underlying vestibular disorder is reached. Recent advances in artificial intelligence promise novel strategies for the diagnosis and treatment of patients with this common symptom. Human analysts may experience difficulties manually extracting patterns from large clinical datasets. Machine learning techniques can be used to visualize, understand, and classify clinical data to create a computerized, faster, and more accurate evaluation of vertiginous disorders. Practitioners can also use them as a teaching tool to gain knowledge and valuable insights from medical data. This paper provides a review of the literatures from 1999 to 2021 using various feature extraction and machine learning techniques to diagnose vertigo disorders. This paper aims to provide a better understanding of the work done thus far and to provide future directions for research into the use of machine learning in vertigo diagnosis.

Investigating Performance of cVEMP and oVEMP in the Identification of Superior Canal Dehiscence in Relation to Dehiscence Location and Size

Compare the sensitivity and specificity of cVEMP (500 Hz), oVEMP (500 Hz and 4 kHz) in the identification of SSCD. A secondary objective was to identify the influence of dehiscence size and location on cVEMP and oVEMP responses. Methods: Individuals with unilateral (n = 16) and bilateral (n = 10) scan confirmed SSCD were assessed using air-conducted cVEMP and oVEMP Results: For cVEMP, an amplitude cutoff of 286.9 μV or a threshold cutoff of 67.5 dBnHL revealed, respectively, a sensitivity of 75% and 70.6% and a specificity of 69.4% and 100%. For oVEMP (500 Hz), an amplitude cutoff of 10.8 μV or a threshold cutoff of 77.5 dBnHL revealed a sensitivity of 83.33% and a specificity of 87.5% and 80%, respectively. oVEMP (4 kHz), an amplitude cutoff of 3.1 μV, revealed a high specificity of 100% but a low sensitivity of 47.2%. A positive correlation was noted between the length of the SSCD and the cVEMP and oVEMP (500 Hz) thresholds and cVEMP amplitude. Conclusions: Our results support the use of oVEMP in the identification of SSCD. The presence of oVEMP (500 Hz) with an amplitude higher or equal to 10.8 μV, a threshold lower or equal to 77.5 dBnHL or oVEMP (4 kHz) amplitude of 3.1 μV represents the most useful to identify SSCD.

Hearing Outcomes After Surgical Manipulation of the Membranous Labyrinth During Superior Semicircular Canal Dehiscence Plugging or Posterior Semicircular Canal Occlusion

OBJECTIVE

To analyze audiometric data after surgical manipulation of the membranous labyrinth during plugging of superior semicircular canal dehiscence (SSCD) or posterior semicircular canal occlusion (PSCO) for benign paroxysmal positional vertigo.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Patients undergoing plugging of SSCD or PSCO between 2009 and 2019.

MAIN OUTCOME MEASURES

Pre- and postoperative audiometric data were collected per AAO-HNS guidelines. Hearing outcomes at initial and last follow-up were compared. Subanalyses were performed for surgical approach and age.

RESULTS

Eighty-seven total procedures in 76 patients including 43 middle cranial fossa for SSCD, 29 transmastoid SSCD, and 15 PSCO. Mean preoperative air-conduction-pure-tone averages was 21.1±14.9 dB compared with 26.1 ± 19.6 dB at initial follow-up and 24.4 ± 18.6 dB at last follow-up (p = 0.006). Mean preoperative bone-conduction-pure-tone average was 14.3 ± 11.9 dB compared with 18.3 ± 15.6 dB at initial follow-up and 18.5 ± 16.9 dB at last follow-up (p < 0.001). There were five cases of hearing loss >20 dB including one case of profound sensorineural hearing loss >55 dB. PSCO resulted in the most hearing loss at initial follow-up but largely resolves with time. Transmastoid approaches for SSCD resulted in more hearing loss compared with middle cranial fossa. Hearing outcomes were generally stable for SSCD approaches but showed improvement over time for PSCO. Age >50 was associated with greater hearing loss of 5.2 ± 11.1 dB compared with 1.3 ± 10.5 dB but did not reach statistical significance (p = 0.110).

CONCLUSIONS

Surgical manipulation of the membranous labyrinth results in statistically significant hearing loss in a pooled analysis. Transient hearing loss is observed in PSCO and TM SSCD plugging was associated with postoperative hearing loss. There was a trend toward increased hearing loss in patients >50 years old.

Superior semicircular canal dehiscence syndrome: Diagnostic criteria consensus document of the committee for the classification of vestibular disorders of the Bárány Society

This paper describes the diagnostic criteria for superior semicircular canal dehiscence syndrome (SCDS) as put forth by the classification committee of the Bárány Society. In addition to the presence of a dehiscence of the superior semicircular canal on high resolution imaging, patients diagnosed with SCDS must also have symptoms and physiological tests that are both consistent with the pathophysiology of a ‘third mobile window’ syndrome and not better accounted for by another vestibular disease or disorder. The diagnosis of SCDS therefore requires a combination of A) at least one symptom consistent with SCDS and attributable to ‘third mobile window’ pathophysiology including 1) hyperacusis to bone conducted sound, 2) sound-induced vertigo and/or oscillopsia time-locked to the stimulus, 3) pressure-induced vertigo and/or oscillopsia time-locked to the stimulus, or 4) pulsatile tinnitus; B) at least 1 physiologic test or sign indicating that a ‘third mobile window’ is transmitting pressure including 1) eye movements in the plane of the affected superior semicircular canal when sound or pressure is applied to the affected ear, 2) low-frequency negative bone conduction thresholds on pure tone audiometry, or 3) enhanced vestibular-evoked myogenic potential (VEMP) responses (low cervical VEMP thresholds or elevated ocular VEMP amplitudes); and C) high resolution computed tomography (CT) scan with multiplanar reconstruction in the plane of the superior semicircular canal consistent with a dehiscence. Thus, patients who meet at least one criterion in each of the three major diagnostic categories (symptoms, physiologic tests, and imaging) are considered to have SCDS.

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.

Optimized Diagnostic Approach to Patients Suspected of Superior Semicircular Canal Dehiscence

OBJECTIVES

Current methods of diagnosing superior semicircular canal dehiscence syndrome (SCDS) include a clinical exam, audiometric testing, temporal bone computer tomography (CT) imaging, and vestibular evoked myogenic potential (VEMP) testing. The main objective of this study was to develop an improved diagnostic approach to SCDS optimized for accuracy, efficiency, and safety that utilizes clinical presentation, audiometric testing, CT imaging, high-frequency cervical VEMP (cVEMP) testing, and patient treatment preference. A secondary aim was to investigate the cost associated with the current versus proposed diagnostic paradigms.

DESIGN

All patients who underwent cVEMP testing since introduction of the 2 kHz cVEMP in our clinical protocol in July 2018 were screened. Patients suspected of SCDS based upon symptoms who also had available audiogram, CT scan, and 2 kHz cVEMP were included (58 ears). Patients were categorized as dehiscent, thin, or not dehiscent based on their CT scan. Symptom prevalence and cVEMP outcomes were analyzed and compared for all groups. The accuracy of the 2 kHz cVEMP was calculated using CT imaging as the standard. Using a combination of patient symptomatology, audiometric, CT and 2 kHz cVEMP data, as well as patient preference, a best clinical practice approach was developed. The cost associated with this approach was calculated and compared with cost of the current SCDS diagnostic workup using Medicare reimbursement rates.

RESULTS

In the overall patient population suspected of SCDS based on clinical presentation, the sensitivity and specificity of 2 kHz cVEMP were 76% and 100%, respectively, while the positive and negative predictive values were 100% and 84.6%, assuming that the CT scan finding was correct. Autophony was the most common symptom in patients who had both superior semicircular canal dehiscence on CT imaging plus abnormal 2 kHz cVEMP (p < 0.001). Combining patient symptomatology, 2 kHz normalized peak to peak cVEMP amplitude, and patient treatment preference to determine, which patients should undergo CT scanning resulted in a potential cost reduction between 45% and 61%.

CONCLUSION

In patients suspected of SCDS based on their clinical presentation, the combination of symptomatology, 2 kHz cVEMP data, and patient preference can be used to determine which patients should undergo CT scanning, resulting in a diagnostic cost reduction and reduced patient radiation exposure.

Measuring Vestibular Contributions to Age-Related Balance Impairment: A Review

Aging is associated with progressive declines in both the vestibular and human balance systems. While vestibular lesions certainly contribute to imbalance, the specific contributions of age-related vestibular declines to age-related balance impairment is poorly understood. This gap in knowledge results from the absence of a standardized method for measuring age-related changes to the vestibular balance pathways. The purpose of this manuscript is to provide an overview of the existing body of literature as it pertains to the methods currently used to infer vestibular contributions to age-related imbalance.

Bone-Conducted oVEMP Latency Delays Assist in the Differential Diagnosis of Large Air-Conducted oVEMP Amplitudes

Background: A sensitive test for Superior Semicircular Canal Dehiscence (SCD) is the air-conducted, ocular vestibular evoked myogenic potential (AC oVEMP). However, not all patients with large AC oVEMPs have SCD. This retrospective study sought to identify alternate diagnoses also producing enlarged AC oVEMPs and investigated bone-conducted (BC) oVEMP outcome measures that would help differentiate between these, and cases of SCD.

Methods: We reviewed the clinical records and BC oVEMP results of 65 patients (86 ears) presenting with dizziness or balance problems who underwent CT imaging to investigate enlarged 105 dB nHL click AC oVEMP amplitudes. All patients were tested with BC oVEMPs using two different stimuli (1 ms square-wave pulse and 8 ms 125 Hz sine wave). Logistic regression and odds ratios were used to determine the efficacy of BC oVEMP amplitudes and latencies in differentiating between enlarged AC oVEMP amplitudes due to dehiscence from those with an alternate diagnosis.

Results: Fifty-three ears (61.6%) with enlarged AC oVEMP amplitudes were identified as having frank dehiscence on imaging; 33 (38.4%) had alternate diagnoses that included thinning of the bone covering (near dehiscence, n = 13), vestibular migraine (n = 12 ears of 10 patients), enlarged vestibular aqueduct syndrome (n = 2) and other causes of recurrent episodic vertigo (n = 6). BC oVEMP amplitudes of dehiscent and non-dehiscent ears were not significantly different (p > 0.05); distributions of both groups overlapped with the range of healthy controls. There were significant differences in BC oVEMP latencies between dehiscent and non-dehiscent ears for both stimuli (p < 0.001). A prolonged n1 125 Hz latency (>11.5 ms) was the best predictor of dehiscence (odd ratio = 27.8; 95% CI:7.0-111.4); abnormal n1 latencies were identified in 79.2% of ears with dehiscence compared with 9.1% of ears without dehiscence.

Conclusions: A two-step protocol of click AC oVEMP amplitudes and 125 Hz BC oVEMP latency measures optimizes the specificity of VEMP testing in SCD.

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.

Vestibular Evoked Myogenic Potential (VEMP) Testing for Diagnosis of Superior Semicircular Canal Dehiscence

Superior semicircular canal dehiscence is a bony defect of the superior semicircular canal, which can lead to a variety of auditory and vestibular symptoms. The diagnosis of superior semicircular canal dehiscence (SCD) can be challenging, time consuming, and costly. The clinical presentation of SCD patients resembles that of other otologic disease, necessitating objective diagnostics. Although temporal bone CT imaging provides excellent sensitivity for SCD detection, it lacks specificity. Because the treatment of SCD is surgical, it is crucial to use a highly specific test to confirm the diagnosis and avoid false positives and subsequent unnecessary surgery. This review provides an update on recent improvements in vestibular evoked myogenic potential (VEMP) testing for SCD diagnosis. Combining audiometric and conventional cervical VEMP results improves SCD diagnostic accuracy. High frequency VEMP testing is superior to all other methods described to date. It is highly specific for the detection of SCD and may be used to guide decision-making regarding the need for subsequent CT imaging. This algorithmic sequential use of testing can substantially reduce radiation exposure as well as cost associated with SCD diagnosis.

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.

The occlusion effect in bone conducted cVEMP

BACKGROUND

Vestibular evoked myogenic potentials (VEMP) are transient alteration in tonic activity of muscles elicited by auditory stimulation of the otolithic organs of the ear. VEMP can be triggered by auditory stimulation via air or bone conduction. Occlusion of the external auditory meatus has long been known to decrease thresholds for sound perception medicated by the cochlea.

OBJECTIVE

Proof that the occlusion effect is present for bone conducted (BC) cervical VEMPs (cVEMP).

METHODS

Measurement of the thresholds and raw amplitudes of BC-VEMPs in twenty healthy adults with the external auditory canal open and occluded.

RESULTS

Thresholds for BC-VEMPs were similar for the open vs. the occluded condition. However, amplitudes were statistically significantly higher in the occluded (average 76.34μV) vs. open group (average 69.9μV).

CONCLUSIONS

The occlusion effect is present in cVEMPs. This finding, described herein for the first time, has a number of clinical implications such as the surgically altered ear and the use of occluding hearing aids.

A new and simple test for diagnosis and prognosis in children with otitis media with effusion: cVEMP

Aim/objectives: A typical vestibular stimulated myogenic potential (VEMP) response depends on suitable sound transfer from the middle ear to inner ear. This transfer is degraded at various degrees in otitis media with effusion (OME). In cases where the effusion is reduced by treating the OME, response to VEMP test can be obtained Backgrounds: In this study we aimed to compare preoperative and postoperative VEMP values of children who were applied ventilation tube for OME and to compare these values and VEMP values of healthy children. Materials and methods: Forty healthy and 40 patients with OME aged between 4 and 16 years were used for the study. VEMP test was performed before and after the surgery. Results: Significant decrease was seen in p13 and n23 values of patient group (p < .05). Statistically significant increase was seen in postoperative amplitudes of patient group (p < .05). Conclusions: Increased VEMP responses in children with OME have shown that dysfunction of middle ear caused vestibular dysfunction. We think that VEMP test can be used to follow up children with OME as a test for showing improvement. Significance: The VEMP test can be used a diagnostic and prognostic test in the diagnosis and follow-up of children with OME.

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.

Toward Optimizing VEMP: Calculating VEMP Inhibition Depth With a Generic Template

OBJECTIVES

Cervical vestibular evoked myogenic potentials (cVEMP) indirectly reveal the response of the saccule to acoustic stimuli through the inhibition of sternocleidomastoid muscle electromyographic response. VEMP inhibition depth (VEMPid) is a recently developed metric that estimates the percentage of saccular inhibition. VEMPid provides both normalization and better accuracy at low response levels than amplitude-normalized cVEMPs. Hopefully, VEMPid will aid in the clinical assessment of patients with vestibulopatholgy. To calculate VEMPid a template is needed. In the original method, a subject's own cVEMP was used as the template, but this method can be problematic in patients who do not have robust cVEMP responses. We hypothesize that a "generic" template, created by assembling cVEMPs from healthy subjects, can be used to compute VEMPid, which would facilitate the use of VEMPid in subjects with pathological conditions.

DESIGN

A generic template was created by averaging cVEMP responses from 6 normal subjects. To compare VEMPid calculations using a generic versus a subject-specific template, cVEMPs were obtained in 40 healthy subjects using 500, 750, and 1000 Hz tonebursts at sound levels ranging from 98 to 123 dB peSPL. VEMPids were calculated both with the generic template and with the subject's own template. The ability of both templates to determine whether a cVEMP was present or not was compared with receiver operating characteristic curves.

RESULTS

No significant differences were found between VEMPid calculations using a generic template versus using a subject-specific template for all frequencies and sound levels. Based on the receiver operating characteristic curves, the subject-specific and generic template did an equally good job at determining threshold. Within limits, the shape of the generic template did not affect these results.

CONCLUSIONS

A generic template can be used instead of a subject-specific template to calculate VEMPid. Compared with cVEMP normalized by electromyographic amplitudes, VEMPid is advantageous because it averages zero when there is no sound stimulus and it allows the accumulating VEMPid value to be shown during data acquisition as a guide to deciding when enough data has been collected.

Cervical Vestibular Evoked Myogenic Potentials in Menière's Disease: A Comparison of Response Metrics

OBJECTIVE

The cervical vestibular evoked myogenic potential (cVEMP) has been used to evaluate patients with Menière's disease (MD). Studied cVEMP metrics include: amplitude, threshold, frequency tuning, and interaural asymmetry ratio (IAR). However, few studies compared these metrics in the same set of MD patients, and methodological differences prevent such a comparison across studies. This study investigates the value of different cVEMP metrics in distinguishing one set of MD patients from age-matched controls.

STUDY DESIGN

Prospective study.

SETTING

Tertiary care center.

PATIENTS

Thirty patients with definite unilateral MD and 23 age-matched controls were prospectively included. All underwent cVEMP testing at 500, 750, 1000, and 2000 Hz on each side. Ears were separated into three groups: affected MD, unaffected MD, and control.

MAIN OUTCOME MEASURES

Sound level functions were obtained at each frequency, and normalized peak-to-peak amplitude (VEMPn), VEMP inhibition depth (VEMPid), threshold, frequency-tuning ratio, and IAR were calculated. For all metrics, the differentiation between MD and control ears was compared using receiver operating characteristic (ROC) curves.

RESULTS

500 Hz cVEMP threshold, VEMPn, and VEMPid were similarly good at distinguishing affected MD ears from healthy ears, with ROC area under the curves (AUCs) of more than 0.828 and optimal sensitivities and specificities of at least 80 and 70%. Combinations of these three metrics yielded slightly larger AUCs (>0.880). Tuning ratios and IAR were less effective in separating healthy from affected ears with AUCs ranging from 0.529 to 0.720.

CONCLUSION

The cVEMP metrics most useful in distinguishing MD patients from healthy controls are threshold, VEMPn, and VEMPid, using 500 Hz stimuli.

Toward Optimizing cVEMP: 2,000-Hz Tone Bursts Improve the Detection of Superior Canal Dehiscence

BACKGROUND

The cervical vestibular evoked myogenic potential (cVEMP) test measures saccular and inferior vestibular nerve function. The cVEMP can be elicited with different frequency stimuli and interpreted using a variety of metrics. Patients with superior semicircular canal dehiscence (SCD) syndrome generally have lower cVEMP thresholds and larger amplitudes, although there is overlap with healthy subjects. The aim of this study was to evaluate which metric and frequency best differentiate healthy ears from SCD ears using cVEMP.

METHODS

Twenty-one patients with SCD and 23 age-matched controls were prospectively included and underwent cVEMP testing at 500, 750, 1,000 and 2,000 Hz. Sound level functions were obtained at all frequencies to acquire threshold and to calculate normalized peak-to-peak amplitude (VEMPn) and VEMP inhibition depth (VEMPid). Third window indicator (TWI) metrics were calculated by subtracting the 250-Hz air-bone gap from the ipsilateral cVEMP threshold at each frequency. Ears of SCD patients were divided into three groups based on CT imaging: dehiscent, thin or unaffected. The ears of healthy age-matched control subjects constituted a fourth group.

RESULTS

Comparing metrics at all frequencies revealed that 2,000-Hz stimuli were most effective in differentiating SCD from normal ears. ROC analysis indicated that for both 2,000-Hz cVEMP threshold and for 2,000-Hz TWI, 100% specificity could be achieved with a sensitivity of 92.0%. With 2,000-Hz VEMPn and VEMPid at the highest sound level, 100% specificity could be achieved with a sensitivity of 96.0%.

CONCLUSION

The best diagnostic accuracy of cVEMP in SCD patients can be achieved with 2,000-Hz tone burst stimuli, regardless of which metric is used.

Animal Models of Vestibular Evoked Myogenic Potentials: The Past, Present, and Future

Vestibular-evoked myogenic potentials (VEMPs) provide a simple and cost-effective means to assess the patency of vestibular reflexes. VEMP testing constitutes a core screening method in a clinical battery that probes vestibular function. The confidence one has in interpreting the results arising from VEMP testing is linked to a fundamental understanding of the underlying functional anatomy and physiology. In this review, we will summarize the key role that studies across a range of animal models have fulfilled in contributing to this understanding, covering key findings regarding the mechanisms of excitation in the sensory periphery, the processing of sensory information in central networks, and the distribution of reflexive output to the motor periphery. Although VEMPs are often touted for their simplicity, work in animals models have emphasized how vestibular reflexes operate within a broader behavioral and functional context, and as such vestibular reflexes are influenced by multisensory integration, governed by task demands, and follow principles of muscle recruitment. We will conclude with considerations of future questions, and the ways in which studies in current and emerging animal models can contribute to further use and refinement of this test for both basic and clinical research purposes.

Laboratory examinations for the vestibular system

PURPOSE OF REVIEW

In the last decades, researchers suggested that clinical assessment of labyrinthine function in detail became easy thanks to video head impulse tests (VHITs), vestibular evoked myogenic potential test (VEMP) and video-oculography (VOG). It has been argued that they can replace electronystagmography, the caloric and rotatory chair tests. This review addresses the latest evaluations of these tests and the opportunities they offer, but also the limitations in clinical practice.

RECENT FINDINGS

The VHIT and suppression head impulse test (SHIMP) are under ideal circumstances able to accurately identify deficits of the VOR in 3D. However, in a relevant part of the patient population, pupil tracking is inaccurate, video-goggles slip and VOR quantification is problematic. The dissociation between the VHIT and caloric test suggests that these tests are complementary. A new 3D-VOG technique claims to quantify eye torsion better than before, opening multiple diagnostic possibilities. VEMPs remain difficult to standardize. Variability in normal cervical vestibular-evoked myogenic potential amplitude is large. VEMPs become smaller or absent with age, raising questions of whether there is a lower normal limit at all. Recent research shows that the labyrinth is directly stimulated in the MRI offering new opportunities for diagnostics and research.

SUMMARY

In clinical practice, the VHIT, SHIMP, VEMP and new 3D-VOG techniques improve diagnostic power. Unfortunately, technical issues or variability prevent reliable quantitative evaluation in a part of the regular patient population. The traditional caloric and rotatory chair test can still be considered as valuable complementary tests.