Easy as 1-2-3: Development and Evaluation of a Simple yet Valid Audiogram-Classification System.

Almost since the inception of the modern-day electroacoustic audiometer a century ago the results of pure-tone audiometry have been characterized by an audiogram. For almost as many years, clinicians and researchers have sought ways to distill the volume and complexity of information on the audiogram. Commonly used approaches have made use of pure-tone averages (PTAs) for various frequency ranges with the PTA for 500, 1000, 2000 and 4000 Hz (PTA4) being the most widely used for the categorization of hearing loss severity. Here, a three-digit triad is proposed as a single-number summary of not only the severity, but also the configuration and bilateral symmetry of the hearing loss. Each digit in the triad ranges from 0 to 9, increasing as the level of the pure-tone hearing threshold level (HTL) increases from a range of optimal hearing (< 10 dB Hearing Level; HL) to complete hearing loss (≥ 90 dB HL). Each digit also represents a different frequency region of the audiogram proceeding from left to right as: (Low, L) PTA for 500, 1000, and 2000 Hz; (Center, C) PTA for 3000, 4000 and 6000 Hz; and (High, H) HTL at 8000 Hz. This LCH Triad audiogram-classification system is evaluated using a large United States (U.S.) national dataset (N = 8,795) from adults 20 to 80 + years of age and two large clinical datasets totaling 8,254 adults covering a similar age range. Its ability to capture variations in hearing function was found to be superior to that of the widely used PTA4.

Clinical Utility of the Standardized Word Recognition Score.

OBJECTIVES: An unexpectedly low word recognition (WR) score may be taken as evidence of increased risk for retrocochlear tumor. We sought to develop evidence for or against using a standardized WR (sWR) score in detecting retrocochlear tumors. The sWR is a z score expressing the difference between an observed WR score and a Speech Intelligibility Index-based predicted WR score. We retrospectively compared the sensitivity and specificity of pure-tone asymmetry-based logistic regression models that incorporated either the sWR or the raw WR scores in detecting tumor cases. Two pure-tone asymmetry calculations were used: the 4-frequency pure-tone asymmetry (AAO) calculation of the American Academy of Otolaryngology-Head and Neck Surgery and a 6-frequency pure-tone asymmetry (6-FPTA) calculation previously optimized to detect retrocochlear tumors. We hypothesized that a regression model incorporating the 6-FPTA calculation and the sWR would more accurately detect retrocochlear tumors. DESIGN: Retrospective data from all patients seen in the audiology clinic at Mayo Clinic in Florida in 2016 were reviewed. Cases with retrocochlear tumors were compared with a reference group with noise- or age-related hearing loss or idiopathic sensorineural hearing loss. Two pure-tone-based logistic regression models were created (6-FPTA and AAO). Into these base models, WR variables (WR, sWR, WR asymmetry [WRΔ], and sWR asymmetry [sWRΔ]) were added. Tumor detection performance for each regression model was compared twice: first, using all qualifying cases (61 tumor cases; 2332 reference group cases), and second, using a data set filtered to exclude hearing asymmetries greater than would be expected from noise-related or age-related hearing loss (25 tumor cases; 2208 reference group cases). The area under the curve and the DeLong test for significant receiver operating curve differences were used as outcome measures. RESULTS: The 6-FPTA model significantly outperformed the AAO model-with or without the addition of WR or WRΔ variables. Including sWR into the AAO base regression model significantly improved disease detection performance. Including sWR into the 6-FPTA model significantly improved disease detection performance when large hearing asymmetries were excluded. In the data set that included large pure-tone asymmetries, area under the curve values for the 6-FPTA + sWR and AAO + sWR models were not significantly better than the base 6-FPTA model. CONCLUSIONS: The results favor the superiority of the sWR computational method in identifying reduced WR scores in retrocochlear cases. The utility would be greatest where undetected tumor cases are embedded in a population heavily representing age- or noise-related hearing loss. The results also demonstrate the superiority of the 6-FPTA model in identifying tumor cases. The 2 computational methods may be combined (ie, the 6-FPTA + sWR model) into an automated tool for detecting retrocochlear disease in audiology and community otolaryngology clinics. The 4-frequency AAO-based regression model was the weakest detection method considered. Including raw WR scores into the model did not improve performance, whereas including sWR into the model did improve tumor detection performance. This further supports the contribution of the sWR computational method for recognizing low WR scores in retrocochlear disease cases.

New bone formation over dehiscent semicircular canal with cartilage cap.

PURPOSE: Cartilage cap resurfacing is a method to seal a superior semicircular canal dehiscence. The purpose of this study was to evaluate the detection of new bone formation after surgical placement of a cartilage cap over a dehiscent semicircular canal. METHODS: In this retrospective review, two neuroradiologists blinded to each other's interpretation reviewed the temporal bones of 20 patients, five of which had a pre-operative computed tomography (CT) exam which was interpreted as unilateral superior semicircular canal dehiscence and with new bone formation following repair on follow-up CT. There were also 15 control subjects. Each neuroradiologist was blinded to history, including post-operative changes, and asked to determine if there was a dehiscence or no dehiscence. RESULTS: Out of the 15 controls, there was 100% inter-observer agreement. On the five post-operative patients, there was agreement in 4/5 that there was no dehiscence post-operatively and 1/5 agreement of dehiscence post-operatively, but ectopic bone adjacent to the dehiscence. CONCLUSION: Our results indicate that new bone formation can be seen at the site of cartilage cap placement over the dehiscence and be interpreted as bony closure of the dehiscence.

CEDRA: A Tool to Help Consumers Assess Risk for Ear Disease.

This article introduces the Consumer Ear Disease Risk Assessment (CEDRA) tool. CEDRA is a brief questionnaire designed to screen for targeted ear diseases. It offers an opportunity for consumers to self-screen for disease before seeking a hearing device and may be used by clinicians to help their patients decide the appropriate path to follow in hearing healthcare. Here we provide highlights of previously published validation in the context of a more thorough description of CEDRA's development and implementation. CEDRA's sensitivity and specificity, using a cut-off score of 4 or higher, was 90% and 72%, respectively, relative to neurotologist diagnoses in the initial training sample used to create the scoring algorithm (n = 246). On a smaller independent test sample (n = 61), CEDRA's sensitivity and specificity were 76% and 80%, respectively. CEDRA has readability levels similar to many other patient-oriented questionnaires in hearing healthcare, and informal reports from pilot CEDRA-providers indicate that the majority of patients can complete it in less than 10 min. As the hearing healthcare landscape changes and provider intercession is no longer mandated, CEDRA provides a measure of safety without creating a barrier to access.

Comparing the International Classification of Functioning, Disability, and Health Core Sets for Hearing Loss and Otorhinolaryngology/Audiology Intake Documentation at Mayo Clinic.

OBJECTIVES: The International Classification of Functioning, Disability, and Health (ICF) Core Sets for Hearing Loss (CSHL) consists of short lists of categories from the entire ICF classification that are thought to be the most relevant for describing the functioning of persons with hearing loss. A comprehensive intake that covers all factors included in the ICF CSHL holds the promise of developing a tailored treatment plan that fully complements the patient's needs. The Comprehensive CSHL contains 117 categories and serves as a guide for multiprofessional, comprehensive assessment. The Brief CSHL includes 27 of the 117 categories and represents the minimal spectrum of functioning of persons with HL for single-discipline encounters or clinical trials. The authors first sought to benchmark the extent to which Audiologist (AUD) and Otorhinolaryngologist (ORL) discipline-specific intake documentation, as well as Mayo Clinic's multidisciplinary intake documentation, captures ICF CSHL categories. DESIGN: A retrospective study design including 168 patient records from the Department of Otorhinolaryngology/Audiology of Mayo Clinic in Jacksonville, Florida. Anonymized intake documentation forms and reports were selected from patient records filed between January 2016 and May 2017. Data were extracted from the intake documentation forms and reports and linked to ICF categories using pre-established linking rules. "Overlap," defined as the percentage of ICF CSHL categories represented in the intake documentation, was calculated across document types. In addition, extra non-ICF CSHL categories (ICF categories that are not part of the CSHL) and extra constructs (constructs that are not part of the ICF classification) found in the patient records were described. RESULTS: The total overlap of multidisciplinary intake documentation with ICF CSHL categories was 100% for the Brief CSHL and 50% for the Comprehensive CSHL. Brief CSHL overlap for discipline-specific documentation fell short at 70% for both AUD and ORL. Important extra non-ICF CSHL categories were identified and included "sleep function" and "motor-related functions and activities," which mostly were reported in relation to tinnitus and vestibular disorders. CONCLUSION: The multidisciplinary intake documentation of Mayo Clinic showed 100% overlap with the Brief CSHL, while important areas of nonoverlap were identified in AUD- and ORL-specific reports. The ICF CSHL provides a framework for describing each hearing-impaired individual's unique capabilities and needs in ways currently not documented by audiological and otological evaluations, potentially setting the stage for more effective individualized patient care. Efforts to further validate the ICF CSHL may require the involvement of multidisciplinary institutions with commonly shared electronic health records to adequately capture the breath of the ICF CSHL.

A Retrospective Estimate of Ear Disease Detection Using the "Red Flags" in a Clinical Sample.

OBJECTIVES: The purpose of this study was to evaluate the specificity and sensitivity of two red flag protocols in detecting ear diseases associated with changes in hearing. DESIGN: The presence of red-flag symptoms was determined in a chart review of 307 adult patients from the Mayo Clinic Florida Departments of Otorhinolaryngology and Audiology. Participants formed a convenience sample recruited for a separate study. Neurotologist diagnosis was the criterion for comparisons. RESULTS: Of the 251 patient files retained for analysis, 191 had one or more targeted diseases and 60 had age- or noise-related hearing loss. Food and Drug Administration red flags sensitivity was 91% (confidence interval [CI], 86 to 95%) and specificity was 72% (CI, 59 to 83%). American Academy of Otolaryngology-Head and Neck Surgery red flags sensitivity was 98% (CI, 95 to 99%) and specificity was 20% (CI, 11 to 32%). CONCLUSIONS: Stakeholders must determine which diseases are meaningful contraindications for hearing aid use and whether these red-flag protocols have acceptable levels of sensitivity and specificity. As direct-to-consumer models of hearing devices increase, a disease detection method that does not require provider intercession would be useful.

Development and Initial Validation of a Consumer Questionnaire to Predict the Presence of Ear Disease.

Importance: The already large population of individuals with age- or noise-related hearing loss in the United States is increasing, yet hearing aids remain largely inaccessible. The recent decision by the US Food and Drug Administration to not enforce the medical examination prior to hearing aid fitting highlights the need to reengineer consumer protections when increasing accessibility. A self-administered tool to estimate ear disease risk would provide disease surveillance without posing an unreasonable barrier to hearing aid procurement. Objective: To develop and validate a consumer questionnaire for the self-assessment of risk for ear diseases associated with hearing loss. Design, Setting, and Participants: The questionnaire was developed using established methods including expert opinion to validate and create questions, and cognitive interviews to ensure that questions were clear to respondents. Exploratory structural equation modeling, logistic regression, and receiver operating characteristic curve analysis were used to determine sensitivity and specificity with blinded neurotologist opinion as the criterion for evaluation. Patients 40 to 80 years old with ear or hearing complaints necessitating a neurotologic examination and a control group of participants with a diagnosis of age- or noise-related hearing loss participated at the Departments of Otorhinolaryngology and Audiology of Mayo Clinic Florida. Main Outcomes and Measures: Sensitivity and specificity of the prototype questionnaire to identify individuals with targeted diseases. Results: Of 307 participants (mean [SD] age, 62.9 [9.8] years; 148 [48%] female), 75% (n = 231) were enrolled with targeted disease(s) identified on neurotologic assessment and 25% (n = 76) with age- or noise-related hearing loss. Participants were randomly divided into a training sample (80% [n = 246; 185 with disease, 61 controls]) and a test sample (20% [n = 61; 46 with disease, 15 controls]). Using a simple scoring method, a sensitivity of 94% (95% CI, 89%-97%) and specificity of 61% (95% CI, 47%-73%) were established in the training sample. Applying this cutoff to the test sample resulted in 85% (95% CI, 71%-93%) sensitivity and 47% (95% CI, 22%-73%) specificity. Conclusions and Relevance: This is the first self-assessment tool designed to assess an individual's risk for ear disease. Our preliminary results demonstrate a high sensitivity to disease detection. A further validated and refined version of this questionnaire may serve as an efficacious tool for improving access to hearing health care while minimizing the risk for missed ear diseases.

Identifying and Prioritizing Diseases Important for Detection in Adult Hearing Health Care.

PURPOSE: The purpose of this research note is to identify and prioritize diseases important for detection in adult hearing health care delivery systems. METHOD: Through literature review and expert consultation, the authors identified 195 diseases likely to occur in adults complaining of hearing loss. Five neurotologists rated the importance of disease on 3 dimensions related to the necessity of detection prior to adult hearing aid fitting. RESULTS: Ratings of adverse health consequences, diagnostic difficulty, and presence of nonotologic symptoms associated with these diseases resulted in the identification of 104 diseases potentially important for detection prior to adult hearing aid fitting. CONCLUSIONS: Current and evolving health care delivery systems, including direct-to-consumer sales, involve inconsistent means of disease detection vigilance prior to device fitting. The first steps in determining the safety of these different delivery methods are to identify and prioritize which diseases present the greatest risk for poor health outcomes and, thus, should be detected in hearing health care delivery systems. Here the authors have developed a novel multidimensional rating system to rank disease importance. The rankings can be used to evaluate the effectiveness of alternative detection methods and to inform public health policy. The authors are currently using this information to validate a consumer questionnaire designed to accurately identify when pre- fitting medical evaluations should be required for hearing aid patients.

The Effect of Repetition Rate on Air-Conducted Ocular Vestibular Evoked Myogenic Potentials (oVEMPs).

PURPOSE: Ocular vestibular evoked myogenic potentials (oVEMPs) are used to describe utricular/superior vestibular nerve function; however, optimal recording parameters have not been fully established. This study investigated the effect of repetition rate on air-conducted oVEMPs. METHOD: Ten healthy adults were evaluated using 500-Hz tone bursts (4-ms duration, Blackman gating, 122 dB pSPL). Four repetition rates were used (1.6, 4.8, 8.3, and 26.6 Hz) and resulting oVEMP response presence, amplitude, amplitude asymmetry, and n1/p1 latency were assessed. RESULTS: Response presence was significantly reduced for 26.6 Hz using monaural stimulation and for 8.3 Hz and 26.6 Hz for binaural stimulation. For monaural stimulation using 1.6, 4.8, and 8.3 Hz, no significant differences were noted for amplitude or latency. Responses obtained using binaural stimulation demonstrated a significant effect of rate on amplitude, with 8.3 Hz producing significantly reduced amplitude. Binaural amplitudes were significantly larger than monaural contralateral responses but with reduced response presence. No significant differences were noted for latency or amplitude asymmetry. CONCLUSION: Using repetition rates of approximately 5 Hz or less may produce more consistent oVEMP response presence with minimal effects on amplitude for monaural or binaural recordings.

Vestibular Function Measurement Devices.

Vestibular function laboratories utilize a multitude of diagnostic instruments to evaluate a dizzy patient. Caloric irrigators, oculomotor stimuli, and rotational chairs produce a stimulus whose accuracy is required for the patient response to be accurate. Careful attention to everything from cleanliness of equipment to threshold adjustments determine on a daily basis if patient data are going to be correct and useful. Instrumentation specifications that change with time such as speed and temperature must periodically be checked using calibrated instruments.

Vestibular evoked myogenic potentials in patients with vestibular migraine.

OBJECTIVE: Literature investigating otolith reflexes in patients with vestibular migraine (VM) is variable and primarily describes the descending saccular pathway. This research aimed to study ocular vestibular evoked myogenic potential (oVEMP) and cervical vestibular evoked myogenic potential (cVEMP) prevalence and response characteristics in patients with suspected VM and in control patients. The purpose is to assess vulnerabilities within the ascending utricular and descending saccular pathways in the VM population. STUDY DESIGN: Retrospective study SETTING: Tertiary academic referral center PATIENTS: 39 adults with VM, 29 control patients MAIN OUTCOME MEASURE(S): Air conducted oVEMPs and cVEMPs measured with 500 Hz tone burst stimuli RESULTS: Age of headache onset was most often in childhood or adolescence, with dizziness onset occurring later. The rate of bilaterally absent oVEMPs was significantly higher (28%, p < 0.01) in the VM group compared with the control group (0%). oVEMP amplitude asymmetry ratios were significantly higher for the definite VM (p < 0.01) and probable VM (p = 0.023) groups than the control group. Eleven patients also had history of concussion; they were significantly more likely to demonstrate bilaterally absent oVEMPs (p < 0.01) in comparison to the control patients. When VM patients with a history of concussion were omitted from analysis, differences in oVEMP amplitude asymmetry (p < 0.01) and bilateral oVEMP absence remained significant (p = 0.015). There were no differences in the rate of bilateral cVEMP presence or response parameters between VM and control groups. CONCLUSION: VEMP presentation differs for some patients diagnosed with VM. The higher rates of abnormal oVEMPs may suggest greater vulnerability within the ascending utricular-ocular pathway in patients with VM.

The effect of muscle contraction level on the cervical vestibular evoked myogenic potential (cVEMP): usefulness of amplitude normalization.

BACKGROUND: The cervical vestibular evoked myogenic potential (cVEMP) is a reflexive change in sternocleidomastoid (SCM) muscle contraction activity thought to be mediated by a saccular vestibulo-collic reflex. CVEMP amplitude varies with the state of the afferent (vestibular) limb of the vestibulo-collic reflex pathway, as well as with the level of SCM muscle contraction. It follows that in order for cVEMP amplitude to reflect the status of the afferent portion of the reflex pathway, muscle contraction level must be controlled. Historically, this has been accomplished by volitionally controlling muscle contraction level either with the aid of a biofeedback method, or by an a posteriori method that normalizes cVEMP amplitude by the level of muscle contraction. A posteriori normalization methods make the implicit assumption that mathematical normalization precisely removes the influence of the efferent limb of the vestibulo-collic pathway. With the cVEMP, however, we are violating basic assumptions of signal averaging: specifically, the background noise and the response are not independent. The influence of this signal-averaging violation on our ability to normalize cVEMP amplitude using a posteriori methods is not well understood. PURPOSE: The aims of this investigation were to describe the effect of muscle contraction, as measured by a prestimulus electromyogenic estimate, on cVEMP amplitude and interaural amplitude asymmetry ratio, and to evaluate the benefit of using a commonly advocated a posteriori normalization method on cVEMP amplitude and asymmetry ratio variability. RESEARCH DESIGN: Prospective, repeated-measures design using a convenience sample. STUDY SAMPLE: Ten healthy adult participants between 25 and 61 yr of age. INTERVENTION: cVEMP responses to 500 Hz tone bursts (120 dB pSPL) for three conditions describing maximum, moderate, and minimal muscle contraction. DATA COLLECTION AND ANALYSIS: Mean (standard deviation) cVEMP amplitude and asymmetry ratios were calculated for each muscle-contraction condition. Repeated measures analysis of variance and t-tests compared the variability in cVEMP amplitude between sides and conditions. Linear regression analyses compared asymmetry ratios. Polynomial regression analyses described the corrected and uncorrected cVEMP amplitude growth functions. RESULTS: While cVEMP amplitude increased with increased muscle contraction, the relationship was not linear or even proportionate. In the majority of cases, once muscle contraction reached a certain "threshold" level, cVEMP amplitude increased rapidly and then saturated. Normalizing cVEMP amplitudes did not remove the relationship between cVEMP amplitude and muscle contraction level. As muscle contraction increased, the normalized amplitude increased, and then decreased, corresponding with the observed amplitude saturation. Abnormal asymmetry ratios (based on values reported in the literature) were noted for four instances of uncorrected amplitude asymmetry at less than maximum muscle contraction levels. Amplitude normalization did not substantially change the number of observed asymmetry ratios. CONCLUSIONS: Because cVEMP amplitude did not typically grow proportionally with muscle contraction level, amplitude normalization did not lead to stable cVEMP amplitudes or asymmetry ratios across varying muscle contraction levels. Until we better understand the relationships between muscle contraction level, surface electromyography (EMG) estimates of muscle contraction level, and cVEMP amplitude, the application of normalization methods to correct cVEMP amplitude appears unjustified.

Dizziness handicap after cartilage cap occlusion for superior semicircular canal dehiscence.

OBJECTIVE: To evaluate the change in self-reported dizziness handicap after surgical repair using the cartilage cap occlusion technique in cases of superior canal dehiscence (SCD). STUDY DESIGN: Repeated measures, retrospective chart review. SETTING: Tertiary referral center. PATIENTS: Twenty patients over a 2-year period who underwent surgical repair of SCD using the cartilage cap occlusion technique. INTERVENTION: Therapeutic. MAIN OUTCOME MEASURE: Preoperative and postoperative Dizziness Handicap Inventory (DHI) questionnaires were completed (median, interquartile range). RESULTS: Preoperative (48, 28-56) and postoperative (33, 19-50) total scores were not significantly different. Scores for patients with moderate/severe preoperative DHI scores (DHI, >30; n = 14) demonstrated significant change (p = 0.001, Wilcoxon paired sample test), whereas those with mild scores did not (DHI, ≤ 30; n = 6; p = 0.67). CONCLUSION: Change in DHI score is variable. As described by DHI score, patients with higher preoperative handicap may demonstrate significant improvement after surgery, whereas those with mild handicap may not. These results are similar to previous reports and indicate that the cartilage cap occlusion technique may provide an alternative to middle fossa craniotomy approach for surgical management of symptomatic SCD.

Pure-tone hearing asymmetry: a logistic approach modeling age, sex, and noise exposure history.

BACKGROUND: Asymmetric hearing loss (AHL) can be an early sign of vestibular schwannoma (VS). However, recognizing VS-induced AHL is challenging. There is no universally accepted definition of a "medically significant pure-tone hearing asymmetry," in part because AHL is a common feature of medically benign forms of hearing loss (e.g., age- or firearm-related hearing loss). In most cases, the determination that an observed AHL does not come from a benign cause involves subjective clinical judgment. PURPOSE: Our purpose was threefold: (1) to quantify hearing asymmetry distributions in a large group of patients with medically benign forms of hearing loss, stratifying for age, sex, and noise exposure history; (2) to assess how previously proposed hearing asymmetry calculations segregate tumor from nontumor cases; and (3) to present the results of a logistic regression method for defining hearing asymmetry that incorporates age, sex, and noise information. RESEARCH DESIGN: Retrospective chart review. STUDY SAMPLE: Five thousand six hundred and sixty-one patients with idiopathic, age- or noise exposure-related hearing loss and 85 untreated VS patients. DATA COLLECTION AND ANALYSIS: Audiometric, patient history, and clinical impression data were collected from 22,785 consecutive patient visits to the audiology section at Mayo Clinic in Florida from 2006 to 2009 to screen for eligibility. Those eligible were then stratified by VS presence, age, sex, and self-reported noise exposure history. Pure-tone asymmetry distributions were analyzed. Audiometric data from VS diagnoses were used to create four additional audiograms per patient to model the hypothetical development of AHL prior to the actual hearing test. The ability of 11 previously defined hearing asymmetry calculations to distinguish between VS and non-VS cases was described. A logistic regression model was developed that integrated age, sex, and noise exposure history with pure-tone asymmetry data. Regression model performance was then compared to existing asymmetry calculation methods. RESULTS: The 11 existing pure-tone asymmetry calculations varied in tumor detection performance. Age, sex, and noise exposure history helped to predict benign forms of hearing asymmetry. The logistic regression model outperformed existing asymmetry calculations and better accounted for normal age-, sex-, and noise exposure-related asymmetry variability. CONCLUSIONS: Our logistic regression asymmetry method improves the clinician's ability to estimate risk of VS, in part by integrating categorical patient history and numeric test data. This form of modeling can enhance clinical decision making in audiology and otology.

Oculo-vestibular recoupling using galvanic vestibular stimulation to mitigate simulator sickness.

INTRODUCTION: Despite improvement in the computational capabilities of visual displays in flight simulators, intersensory visual-vestibular conflict remains the leading cause of simulator sickness (SS). By using galvanic vestibular stimulation (GVS), the vestibular system can be synchronized with a moving visual field in order to lessen the mismatch of sensory inputs thought to result in SS. METHODS: A multisite electrode array was used to deliver combinations of GVS in 21 normal subjects. Optimal electrode combinations were identified and used to establish GVS dose-response predictions for the perception of roll, pitch, and yaw. Based on these data, an algorithm was then implemented in flight simulator hardware in order to synchronize visual and GVS-induced vestibular sensations (oculo-vestibular-recoupled or OVR simulation). Subjects were then randomly exposed to flight simulation either with or without OVR simulation. A self-report SS checklist was administered to all subjects after each session. An overall SS score was calculated for each category of symptoms for both groups. RESULTS: The analysis of GVS stimulation data yielded six unique combinations of electrode positions inducing motion perceptions in the three rotational axes. This provided the algorithm used for OVR simulation. The overall SS scores for gastrointestinal, central, and peripheral categories were 17%, 22.4%, and 20% for the Control group and 6.3%, 20%, and 8% for the OVR group, respectively. CONCLUSIONS: When virtual head signals produced by GVS are synchronized to the speed and direction of a moving visual field, manifestations of induced SS in a cockpit flight simulator are significantly reduced.

The effect of galvanic vestibular stimulation on distortion product otoacoustic emissions.

Galvanic stimulation has long been used as a nonmechanical means of activating the vestibular apparatus through direct action on the vestibular nerve endings. This stimulation has been reported to be safe, but no studies have examined the potential changes in the corresponding cochlear receptors. The aim of the present study was to evaluate the effect of galvanic vestibular stimulation (GVS) on distortion product otoacoustic emissions (DPOAEs). Fourteen subjects underwent DPOAEs during several conditions of GVS. The DPOAEs ranged from ∼ 1 kHz to ∼ 8 kHz at 65/55 dB for f1/f2 and with an f2/f1 ratio of 1.2. The subjects were evaluated at 10 stimulation conditions that ranged from -2.0 mA to +2.0 mA for each frequency. Statistical analysis showed no significant differences in DPOAE amplitudes for all conditions with and without GVS. Results also showed no significant differences between DPOAE amplitudes before and after GVS. Multivariate analysis found subject variability in DPOAE amplitude, which was not thought to be GVS related. Results indicated that GVS produced neither temporary nor permanent changes in DPOAEs.

Bilateral multicanal benign paroxysmal positional vertigo coexisting with a vestibular schwannoma: case report.

We describe a rarely encountered case of coexisting bilateral multicanal benign paroxysmal positional vertigo (BPPV) and vestibular schwannoma in a 56-year-old woman. The patient had presented with a 10-year history of dizziness and imbalance, and her vestibular findings were perplexing. We decided on a working diagnosis of BPPV and began treatment. After several months of canalith repositioning maneuvers had failed to resolve her symptoms, we obtained magnetic resonance imaging, which revealed the presence of the vestibular schwannoma. This case serves as a reminder of the importance of differentiating between central and peripheral vestibular disorders, as well as central and anterior canal BPPV-induced down-beating nystagmus in order to establish the correct diagnosis and initiate appropriate treatment.