Probabilities of Isolated and Co-Occurring Vestibular Disorder Symptom Clusters Identified Using the Dizziness Symptom Profile.

OBJECTIVES: Dizziness is among the most common reasons people seek medical care. There are data indicating patients with dizziness, unsteadiness, or vertigo may have multiple underlying vestibular disorders simultaneously contributing to the overall symptoms. Greater awareness of the probability that a patient will present with symptoms of co-occurring vestibular disorders has the potential to improve assessment and management, which could reduce healthcare costs and improve patient quality of life. The purpose of the current investigation was to determine the probabilities that a patient presenting to a clinic for vestibular function testing has symptoms of an isolated vestibular disorder or co-occurring vestibular disorders. DESIGN: All patients who are seen for vestibular function testing in our center complete the dizziness symptom profile, a validated self-report measure, before evaluation with the clinician. For this retrospective study, patient scores on the dizziness symptom profile, patient age, and patient gender were extracted from the medical record. The dizziness symptom profile includes symptom clusters specific to six disorders that cause vestibular symptoms, specifically: benign paroxysmal positional vertigo, vestibular migraine, vestibular neuritis, superior canal dehiscence, Meniere disease, and persistent postural perceptual dizziness. For the present study, data were collected from 617 participants (mean age = 56 years, 376 women, and 241 men) presenting with complaints of vertigo, dizziness, or imbalance. Patients were evaluated in a tertiary care dizziness specialty clinic from October 2020 to October 2021. Self-report data were analyzed using a Bayesian framework to determine the probabilities of reporting symptom clusters specific to an isolated disorder and co-occurring vestibular disorders. RESULTS: There was a 42% probability of a participant reporting symptoms that were not consistent with any of the six vestibular disorders represented in the dizziness symptom profile. Participants were nearly as likely to report symptom clusters of co-occurring disorders (28%) as they were to report symptom clusters of an isolated disorder (30%). When in isolation, participants were most likely to report symptom clusters consistent with benign paroxysmal positional vertigo and vestibular migraine, with estimated probabilities of 12% and 10%, respectively. The combination of co-occurring disorders with the highest probability was benign paroxysmal positional vertigo + vestibular migraine (~5%). Probabilities decreased as number of symptom clusters on the dizziness symptom profile increased. The probability of endorsing vestibular migraine increased with the number of symptom clusters reported. CONCLUSIONS: Many patients reported symptoms of more than one vestibular disorder, suggesting their symptoms were not sufficiently captured by the symptom clusters used to summarize any single vestibular disorder covered by the dizziness symptom profile. Our results indicate that probability of symptom clusters indicated by the dizziness symptom profile is comparable to prior published work on the prevalence of vestibular disorders. These findings support use of this tool by clinicians to assist with identification of symptom clusters consistent with isolated and co-occurring vestibular disorders.

Test-Retest Reliability of the Dizziness Symptom Profile.

OBJECTIVES: This investigation was conducted to measure the test-retest reliability of the Dizziness Symptom Profile (DSP). The DSP was developed to assist primary care providers, general otolaryngologists, and other health care providers in the development of a differential diagnosis for patients who present with dizziness, vertigo, or unsteadiness. The DSP yields a score ranging from 0 to 100% for each of 7 subscales. Each subscale represents a different diagnosis including benign paroxysmal positional vertigo, Ménière's disease, persistent postural-perceptual dizziness (PPPD), superior semi-circular canal dehiscence, vestibular migraine, vestibular neuritis, and general unsteadiness. DESIGN: Subjects were 150 adult patients (mean age 56.79 years, SD 15.69 years) referred to the Balance Disorders Clinic at Vanderbilt University Medical Center. Subjects completed two administrations of the DSP. The mean interval between test administrations was 1.58 days (SD 1.78 days). The response modes for the DSP were both a 0 to 100 mm visual analog scale (scored 0 mm = "strongly disagree" to 100 mm = "strongly agree") and, by extrapolation, the original 5-point Likert scale where the anchors were "strongly disagree" (scored 0 points) and "strongly agree" (scored 4 points). RESULTS: Pearson correlation coefficients were calculated to assess test-retest reliability for individual DSP items, and ranged from r = 0.67 to 0.91 (mean 0.80; p < 0.001). Cronbach's α coefficients were calculated to assess internal consistency reliability of items comprising the seven subscales. Each subscale had an acceptable level of internal consistency (Cronbach's α coefficients > 0.7) with the exception of PPPD which approached 0.7. Intraclass correlation coefficient estimates and their 95% confidence intervals were also calculated to assess the relative reliability of the subscales. All 7 subscales showed moderate to strong test-retest reliability, with intraclass correlation coefficients ranging from 0.85 to 0.94. Minimal detectable change (MDC) scores were calculated to assess absolute variability/measurement error for the seven subscale scores (which range from 0 to 100%). MDC values ranged from 16% (PPPD) to 25% (unsteadiness). CONCLUSIONS: (1) The test-retest reliability of the DSP is moderate to strong. (2) MDC values for each subscale were determined. (3) The DSP coupled with the Dizziness Handicap Inventory enables the clinician to evaluate the constructs of dizziness impairment, and disability/handicap. (4) The DSP may help provide a window to the natural history of dizziness disease(s). (5) The DSP provides a less biased assessment of the symptoms reported by the patient.

Development and Preliminary Findings of the Dizziness Symptom Profile.

OBJECTIVES: Dizziness, vertigo, and unsteadiness are common complaints of patients who present to primary care providers. These patients often are referred to otology for assessment and management. Unfortunately, there are a small number of specialists to manage these patients. However, there are several dizziness disorders that can be successfully managed by primary care providers if the disorder is properly identified. To assist in the identification of several of the most common dizziness disorders, we developed the dizziness symptom profile (DSP). The DSP is a self-report questionnaire designed to generate one or more differential diagnoses that can be combined with the patient's case history and physical examination. DESIGN: This report describes three investigations. Investigations 1 and 2 (i.e., exploratory and confirmatory investigations, N = 514) describe the development of the DSP. Investigation 3 (N = 195) is a validation study that describes the level of agreement between the DSP completed by the patient, and, the differential diagnosis of the otologist. RESULTS: The final version of the DSP consists of 31 items. Preliminary findings suggest that the DSP is in agreement with the differential diagnoses of ear specialists for Meniere's disease (100% agreement), vestibular migraine (95% agreement), and benign paroxysmal positional vertigo (82% agreement). CONCLUSIONS: Early results suggest that DSP may be useful in the creation of differential diagnoses for dizzy patients that can be evaluated and managed locally. This has the potential to reduce the burden on primary care providers and reduce delays in the diagnosis of common dizziness and vertigo disorders.

Predictive properties of the video head impulse test: measures of caloric symmetry and self-report dizziness handicap.

OBJECTIVES: The purpose of this investigation was to determine whether a predictable relationship existed between self-reported dizziness handicap and video Head Impulse Test (vHIT) results in a large sample of patients reporting to a dizziness clinic. Secondary objectives included describing the characteristics of the vHIT ipsilesional and contralesional vestibulo-ocular reflex slow-phase velocity in patients with varying levels of canal paresis. Finally, the authors calculated the sensitivity and specificity of the vHIT for detecting horizontal semicircular canal impairment using the caloric test as the "gold standard." DESIGN: Participants were 115 adults presenting to a tertiary medical care center with symptoms of dizziness. Participants were administered a measure of self-report dizziness handicap (i.e., Dizziness Handicap Inventory) and underwent caloric testing and vHIT at the same appointment. RESULTS: Results showed that (1) there were no significant group differences (i.e., vHIT normal versus vHIT abnormal) in the Dizziness Handicap Inventory total score, (2) both ipsilesional and contralateral velocity gain decreased with increases in caloric paresis, and (3) a caloric asymmetry of 39.5% was determined to be the cutoff that maximized discrimination of vHIT outcome. CONCLUSIONS: The level of self-reported dizziness handicap is not predicted by the outcome of the vHIT, which is consistent with the majority of published reports describing the poor relationship between quantitative tests of vestibular function and dizziness handicap. Further, the study findings have demonstrated that vHIT and caloric data are not redundant, and each test provides unique information regarding the functional integrity of the horizontal semicircular canal at different points on the frequency spectrum. The vHIT does offer some advantages over caloric testing, but at the expense of sensitivity. The vHIT can be completed in less time, is not noxious to the patient, and requires very little laboratory space. However, the study data show that a caloric asymmetry of 39.5% is required to optimize discrimination between an abnormal and normal vHIT. It is the authors' contention that the vHIT is a complementary test to the balance function examination and should viewed as such rather than as a replacement for caloric testing.

Concordance and discordance in patient and provider perceptions of dizziness.

PURPOSE: The purpose of the present investigation was to determine whether there are significant differences in patient/healthcare provider perceptions of patient's dizziness severity, dizziness disability/handicap, anxiety, and signs of autonomic system activation. MATERIALS AND METHODS: This was a prospective investigation of 30 patient-provider dyads drawn as a sample of convenience from an otology clinic in a large, tertiary care, medical center. Patients completed both the Dizziness Handicap Inventory (DHI) and the Vestibular Symptom Scale (VSS) prior to vestibular function testing. Providers were instructed to complete the same measures following the patient's clinic visit from what they estimated was the patient's point of view. The two measures were analyzed for concordance and discordance. RESULTS: Patient/provider differences in DHI and VSS vertigo subscale scores were not significantly different. However, difference scores on the VSS anxiety/autonomic subscale indicated that providers significantly under-estimated patient anxiety and symptoms of autonomic system activation. CONCLUSIONS: The results suggest that providers may be missing information pertinent to the role anxiety and autonomic system activation may play in patient visits for complaints of dizziness. We suggest that this problem can be mitigated by administrating to patients prior to their clinic visit a standardized measure that quantifies patient self-report dizziness, vertigo, anxiety and autonomic system arousal. Patterns of response by patients on these measures can enable providers to diagnose correctly dizziness disorders that are rooted in clinically significant anxiety either related to, or unrelated to, a history of vestibular system impairment.

Does radiation dose to the vestibule predict change in balance function and patient perceived dizziness following stereotactic radiotherapy for vestibular schwannoma?

OBJECTIVE: To date, the majority of the vestibular schwannoma (VS) literature has focused on tumor control rates, facial nerve function and hearing preservation. Other factors that have been shown to significantly affect quality-of-life (QOL), such as dizziness, remain understudied. The primary objective of the current study is to investigate the association between radiation dose to the vestibule and post-treatment changes in vestibular function and patient reported dizziness handicap. MATERIALS AND METHODS: This is a prospective observational pilot study at a tertiary academic referral center including all subjects that underwent linear accelerator-based stereotactic radiotherapy (SRS) for sporadic VS and completed pre-treatment and post-treatment vestibular testing and Dizziness Handicap Inventory (DHI) questionnaires. Associations between objective vestibular test results, patient-reported DHI scores and radiation dose parameters were investigated. RESULTS: Ten patients met inclusion criteria. Tumor control was achieved in all individuals. There were no statistically significant associations or identifiable trends between radiation dose and change in vestibular function or DHI scores. Notably, the four ears receiving the highest vestibular dose had minimal changes in vestibular function tests and DHI scores. CONCLUSIONS: To the best of our knowledge, no previous reports have described the association between radiation dose to the vestibule and post-treatment changes in vestibular function and patient reported DHI. Based on these preliminary data, radiation dose to the vestibule does not reliably predict change in objective or subjective vestibular outcome measures.

The effects of amplitude normalization and EMG targets on cVEMP interaural amplitude asymmetry.

OBJECTIVES: The purpose of this investigation was to determine whether the use of visual feedback of tonic electromyographic (EMG) activity, or the use of amplitude normalization techniques would reduce significantly the variability in cervical vestibular evoked myogenic potential (cVEMP) P13-N23 interaural amplitude asymmetry data in otologically and neurologically intact children and adults. DESIGN: There were 97 subjects, both pediatric and adult, from whom the authors recorded cVEMPs with and without the use of an EMG target and amplitude normalization techniques. The four conditions were: (1) conventional recording (condition 1), (2) conventional recording with an EMG target (condition 2), (3) same as condition 1, with the addition of postacquisition amplitude normalization techniques, and (4) same as condition 2, with the addition of postacquisition amplitude normalization techniques. The absolute peak to peak amplitude of positive-negative response (P13-N23), absolute latency of P13, and the left or right amplitude asymmetry of P13-N23 were measured. RESULTS: Neither P13-N23 amplitudes nor latencies, neither mean root mean square (RMS) of the full wave rectified EMG activity, nor the standard deviation of the RMS EMG activity differed significantly when subjects were, and were not, asked to ensure their tonic EMG activity exceeded a visual target (i.e., representing >50 µV RMS EMG). Amplitude normalization of the cVEMP waveforms failed to reduce significantly the variability in the amplitude asymmetry data. CONCLUSIONS: Activating the sternocleidomastoid muscle with the patient in a semirecumbent position, with head turned away from the stimulated ear and head elevated (i.e., an optimal activation technique) was sufficient to produce the highest amplitude cVEMPs with an acceptable amount of variability in subjects of all ages. Group data suggested that the use of visual targets and amplitude normalization routines did not reduce significantly the variability in cVEMP interaural amplitude asymmetry measures. However, in isolated cases amplitude normalization converted an "abnormal" cVEMP into a "normal" cVEMP although the reverse occurred as well, suggesting that these techniques may be beneficial for a subset of patients receiving a less than perfectly administered test procedure.

Effects of age on the tuning of the cVEMP and oVEMP.

OBJECTIVES: The purpose of the present investigation was to define for young, middle-aged, and older adults the optimal frequency (cies) to record both the cervical vestibular-evoked myogenic potential (cVEMP) and the ocular vestibular-evoked myogenic potential (oVEMP). Further, this study aimed to describe age-related changes in the tuning of these two vestibular-evoked myogenic potentials. DESIGN: This was a prospective study. Participants were 39 healthy adults (mean age 46.3 ± 15.7 years; range = 22 to 78 years; 15 men) equally divided into 3 age groups of 13 participants each: young adult (18 to 39 years), middle age (40 to 59 years), and old adult (≥60 years). cVEMPs and oVEMPs were recorded using air-conduction tone bursts at stimulus frequencies of 125, 250, 500, 750, 1000, 1500, and 2000 Hz presented at 127 dB pSPL. RESULTS: There was a significant main effect of age group and frequency on the amplitude of both the cVEMP and the oVEMP. Amplitudes were largest for the Young adult group for the cVEMP and for the young adult and Middle age group for the oVEMP. The largest average peak-to-peak amplitude occurred in response to a 750 Hz tone burst for both responses. No significant differences in mean amplitude of the cVEMP or oVEMP were observed for 500, 750, or 1000 Hz stimuli. There was a significant interaction of age group and frequency for the cVEMP, suggesting a loss of tuning for the old adult group. Compared with the young adult group, the tuning of the cVEMP and oVEMP for the older adjults appeared to shift to a higher frequency. CONCLUSION: There is no sharp tuning in the saccule and utricle. Instead, there is a range of best frequencies that may be used to evoke the cVEMP and oVEMP responses. The results of the present investigation also demonstrate that the optimal stimulus frequency to elicit a VEMP may change with age. Accordingly, 500 Hz may not be the ideal frequency to elicit VEMPs for all age groups. For this reason, in cases where the VEMP response is absent at 500 Hz it is recommended that attempts be made to record the VEMP for tone-burst frequencies of 750 or 1000 Hz.

Clinical characteristics associated with isolated unilateral utricular dysfunction.

PURPOSE: The ocular vestibular evoked myogenic potential (oVEMP) represents the sound-induced activation of extraocular muscles and is believed to originate from the utricle and superior vestibular nerve. Isolated unilateral oVEMP abnormalities with otherwise normal balance function test (BFT) results have not yet been characterized in a large patient series, and their clinical significance remains unclear. MATERIALS AND METHODS: Retrospective review of adult patients with vestibular complaints at a tertiary academic neurotologic referral center was performed. Patients with isolated unilateral oVEMP abnormalities were identified. The prevalence of vestibular symptoms and results of the Dizziness Handicap Inventory (DHI) and Hospital Anxiety and Depression Scale (HADS) were compared between these patients and those with normal BFT results. RESULTS: Thirty-one adult patients with isolated unilateral oVEMP abnormalities were identified (71% female, mean age 48 ± 14 years). Presenting complaints included vertigo in 53%, non-vertiginous dizziness in 68%, postural instability in 52%, and swaying/rocking sensation in 13%. Significant differences were observed in the percentage of patients with postural instability (p=0.046) and swaying/rocking sensation (p=0.04) when comparing the abnormal oVEMP group to patients with a normal BFT battery. No differences were observed when comparing other symptoms, age, gender, diagnoses, and DHI/HADS scores between groups. CONCLUSION: This is the largest series to date reporting on patients with isolated unilateral oVEMP abnormalities. Our results suggest this population may demonstrate an increased prevalence of postural instability and swaying/rocking sensation. Other measures of postural stability may further characterize the vestibular impairments associated with isolated unilateral utricular dysfunction.

The tinnitus functional index: development of a new clinical measure for chronic, intrusive tinnitus.

OBJECTIVES: Chronic subjective tinnitus is a prevalent condition that causes significant distress to millions of Americans. Effective tinnitus treatments are urgently needed, but evaluating them is hampered by the lack of standardized measures that are validated for both intake assessment and evaluation of treatment outcomes. This work was designed to develop a new self-report questionnaire, the Tinnitus Functional Index (TFI), that would have documented validity both for scaling the severity and negative impact of tinnitus for use in intake assessment and for measuring treatment-related changes in tinnitus (responsiveness) and that would provide comprehensive coverage of multiple tinnitus severity domains. DESIGN: To use preexisting knowledge concerning tinnitus-related problems, an Item Selection Panel (17 expert judges) surveyed the content (175 items) of nine widely used tinnitus questionnaires. From those items, the Panel identified 13 separate domains of tinnitus distress and selected 70 items most likely to be responsive to treatment effects. Eliminating redundant items while retaining good content validity and adding new items to achieve the recommended minimum of 3 to 4 items per domain yielded 43 items, which were then used for constructing TFI Prototype 1.Prototype 1 was tested at five clinics. The 326 participants included consecutive patients receiving tinnitus treatment who provided informed consent-constituting a convenience sample. Construct validity of Prototype 1 as an outcome measure was evaluated by measuring responsiveness of the overall scale and its individual items at 3 and 6 mo follow-up with 65 and 42 participants, respectively. Using a predetermined list of criteria, the 30 best-functioning items were selected for constructing TFI Prototype 2.Prototype 2 was tested at four clinics with 347 participants, including 155 and 86 who provided 3 and 6 mo follow-up data, respectively. Analyses were the same as for Prototype 1. Results were used to select the 25 best-functioning items for the final TFI. RESULTS: Both prototypes and the final TFI displayed strong measurement properties, with few missing data, high validity for scaling of tinnitus severity, and good reliability. All TFI versions exhibited the same eight factors characterizing tinnitus severity and negative impact. Responsiveness, evaluated by computing effect sizes for responses at follow-up, was satisfactory in all TFI versions.In the final TFI, Cronbach's alpha was 0.97 and test-retest reliability 0.78. Convergent validity (r = 0.86 with Tinnitus Handicap Inventory [THI]; r = 0.75 with Visual Analog Scale [VAS]) and discriminant validity (r = 0.56 with Beck Depression Inventory-Primary Care [BDI-PC]) were good. The final TFI was successful at detecting improvement from the initial clinic visit to 3 mo with moderate to large effect sizes and from initial to 6 mo with large effect sizes. Effect sizes for the TFI were generally larger than those obtained for the VAS and THI. After careful evaluation, a 13-point reduction was considered a preliminary criterion for meaningful reduction in TFI outcome scores. CONCLUSIONS: The TFI should be useful in both clinical and research settings because of its responsiveness to treatment-related change, validity for scaling the overall severity of tinnitus, and comprehensive coverage of multiple domains of tinnitus severity.

The effect of EMG magnitude on the masseter vestibular evoked myogenic potential (mVEMP).

Introduction: The masseter vestibular evoked myogenic potential (mVEMP) is a bilaterally generated, electromyographically (EMG)-mediated response innervated by the trigeminal nerve. The purpose of the present investigation was to 1) determine whether subjects could accurately achieve and maintain a range of EMG target levels, 2) to examine the effects of varied EMG levels on the latencies and amplitudes of the mVEMP, and 3) to investigate the degree of side-to-side asymmetry and any effects of EMG activation. Methods: Subjects were nine neurologically and otologically normal young adults. A high-intensity tone burst was presented monaurally while subjects were seated upright and asked to match a range of EMG target levels by clenching their teeth. Recordings were made from the ipsilateral and contralateral masseter muscles referenced to the ear being monaurally stimulated. Results: We found that the tonic EMG target had no effect on mVEMP latency. Additionally, although mVEMP amplitudes "scaled" to the EMG target, there was a tendency for the subjects' EMG level to "undershoot" the EMG target levels greater than 50 µV. While some individuals did generate differences in EMG activation between sides, there were no significant differences on average EMG activation between sides. Further, while average corrected amplitude asymmetry was similar across EMG targets, some individuals demonstrated large, corrected amplitude asymmetry ratios. Conclusions: The results of this investigation suggest that, as with cVEMP recordings, the underlying EMG activation may vary between subjects and could impact mVEMP amplitudes, yet could be mitigated by amplitude correction techniques. Further it is important to be aware that even young normal subjects have difficulty maintaining large, tonic EMG activity during the mVEMP recording.

Agreement Between Caloric and Horizontal Video Head Impulse Testing in School-Aged Children Presenting With Dizziness.

OBJECTIVE: The purpose of this investigation was to determine the relationship between the horizontal semicircular canal video head impulse test (hvHIT) and the caloric test in a sample of school-age children evaluated due to complaints of dizziness or imbalance. In adults, these two tests provide different but complementary information regarding vestibular function and/or pathology. However, the most common causes of vestibular loss in children are different than those in adults, and it is not clear how these two tests of horizontal semicircular canal function are related in a pediatric population. METHOD: This is a retrospective study of electronic records of pediatric patients (< 18 years old) who were referred for vestibular function testing and completed both hvHIT and caloric testing. Agreement between both test results was evaluated by examining measures of sensitivity, specificity, and calculating Cohen's kappa. RESULTS: Results from 117 patients (mean age = 13.7 years, age range: 8-17 years, 37 males) were analyzed. Most patients (97/115 [84.3%]) demonstrated both normal hvHIT and caloric test results. Compared to caloric testing, the hvHIT had poor sensitivity (38.9%) and excellent specificity (98.0%). Cohen's kappa analysis revealed moderate agreement between the methods (coefficient = 0.49 [0.24, 0.73]). Where disagreement between the two tests occurred, the final diagnosis was not contingent on either test result. CONCLUSIONS: There is a moderate agreement between the hvHIT and the caloric test in pediatric patients presenting to a tertiary care medical center for a vestibular evaluation. Most patients in this cohort presented with normal findings. The specificity of hvHIT was excellent, although the sensitivity was low. This may be related to the low prevalence of peripheral vestibular system disease in this study cohort, and these results do not generalize to centers that serve populations of children where vestibular disorders are more prevalent (e.g., children with sensorineural hearing loss).

Insensitivity of the "Romberg test of standing balance on firm and compliant support surfaces" to the results of caloric and VEMP tests.

OBJECTIVE: The objective of this study was to assess the sensitivity, specificity, and positive and negative predictive value of the Romberg Test of Standing Balance on Firm and Compliant Support Surfaces (RTSBFCSS) for the identification of patients with vestibular system impairments affecting the horizontal semicircular canal, saccule, and/or inferior and superior vestibular nerves. The RTSBFCSS was developed for the National Health and Nutrition Examination Survey (NHANES) and was used recently to estimate the numbers of individuals aged 40 yr or older with vestibular system impairments among the general population of the United States. DESIGN: A retrospective analysis of the medical records of 103 consecutive patients aged 40 yr or older (mean age 59 ± 12 yr, 71 females) who had undergone vestibular assessment at the Balance Disorders Clinic at the Vanderbilt University School of Medicine. Patients with complete electro- or videonystagmography testing, cervical vestibular evoked myogenic potential (cVEMP) testing, and the RTSBFCSS screening test were included in the analysis. A series of 2 × 2 tables were created that represented the number of "true positives," "true negatives," "false positives," and "false negatives" of the RTSBFCSS under conditions where the caloric test was abnormal and then separately where the cVEMP test was abnormal. The data were analyzed in a manner such that sensitivity, specificity, and both positive and negative predictive value of the RTSBFCSS could be calculated. RESULTS: When the caloric test was used as the criterion standard and the subject selection criteria in the NHANES study were used (i.e., subjects who were able to maintain postural stability for trials 1-3 of the RTSBFCSS; N = 45), the sensitivity and specificity of the RTSBFCSS to impairment of the horizontal semicircular canal or superior vestibular nerve were 55% and 64%, respectively, yielding positive and negative predictive values of 55% and 64%, respectively. When all patients aged 40 yr or older were evaluated (N = 103), the sensitivity and specificity were 61% and 58%, respectively, yielding positive and negative predictive values of 39% and 78%, respectively. Using the cVEMP test as the criterion standard for the detection of impairment affecting the saccule and/or inferior vestibular nerve did not improve the performance criteria of the NHANES screening measure. CONCLUSIONS: The RTSBFCSS should not be used as a screening measure for vestibular impairment.

Normal characteristics of the ocular vestibular evoked myogenic potential.

BACKGROUND: Stimulus-evoked electromyographic changes can be recorded from the extraocular muscles. These short-latency negative-polarity evoked myogenic potentials are called ocular vestibular evoked myogenic potentials (oVEMPs). To date there has not yet been a large-scale study examining the effects of age on the amplitude, latency, threshold, and interaural differences of the oVEMP to air-conducted stimuli. Further, before the oVEMP can become a useful clinical tool, the test-retest reliability of the response must be established. The oVEMP response, once more completely understood, may provide diagnostic information that is complementary to the cervical vestibular evoked myogenic potential (cVEMP; i.e., sternocleidomastoid muscle). PURPOSE: To describe the normal characteristics of oVEMP in a cohort of age-stratified subjects, to assess the test-retest reliability of the oVEMP, and to determine if reference contamination occurs using a common recommended infraorbital reference electrode derivation. RESEARCH DESIGN: A prospective, descriptive study design was used for an investigation with a threefold purpose in which oVEMP recordings were made from the extraocular muscles (e.g., inferior oblique muscle). STUDY SAMPLE: Fifty otologically and neurologically normal adults and children served as subjects. Subjects ranged in age from 8 to 88 yr. DATA COLLECTION AND ANALYSIS: In Investigation 1, oVEMPs were recorded from the ipsilateral and contralateral inferior oblique muscles for all subjects. The stimulus was a 95 dB nHL 500 Hz tone burst. Next, oVEMP thresholds were obtained. Amplitude, latency, and thresholds were tabulated, and descriptive statistics were used to calculate normative values. Age-related differences in oVEMP component latencies, amplitudes, interaural amplitude asymmetries (IAAs), and thresholds were determined using an analysis of variance. In Investigation 2, oVEMPs were recorded twice in 10 subjects, once (test) and once approximately 10 weeks later (retest). Test-retest reliability for the oVEMP peak-to-peak amplitude, n1 latency, p1 latency, n1 threshold, and IAA were assessed with intraclass correlation coefficients (ICCs) calculated using a two-way random-effects, absolute-agreement model. In Investigation 3, a four-channel oVEMP recording was conducted in 10 subjects. Both observational methods and paired-sample t-tests were used to evaluate the effect that reference electrode location had on the oVEMP. RESULTS: oVEMP responses were present bilaterally in 90% of our subjects. The upper limit of oVEMP amplitude asymmetry, defined as the mean plus two standard deviations, was 34% (mean = 14%, SD 10), and the mean n1 latency was 12.5 (SD 1.0) msec. The amplitude of the response significantly decreased and the threshold significantly increased with increasing age, with the greatest age effects occurring in subjects 50 yr and older. Test-retest reliability was acceptable (ICCs for the measurement variables ranged from .53 to .87). Using conventional recommended recording techniques, evidence of reference contamination occurred for all subjects, resulting in a mean amplitude reduction of 30% (range = 18%-43%). CONCLUSIONS: Age results in systematic changes in oVEMP measurement parameters. The test-retest reliability is acceptable, and reference contamination averaging 30% is guaranteed using a second infraorbital electrode as the inverting input (i.e., reference electrode) for bipolar recordings. The oVEMP can be used as a complementary diagnostic tool to the cVEMP in evaluating subjects with suspected peripheral vestibular disorders.

The influence of unilateral saccular impairment on functional balance performance and self-report dizziness.

BACKGROUND: Postural stability in humans is largely maintained by vestibular, visual, and somatosensory inputs to the central nervous system. Recent clinical advances in the assessment of otolith function (e.g., cervical and ocular vestibular evoked myogenic potentials [cVEMPs and oVEMPs], subjective visual vertical [SVV] during eccentric rotation) have enabled investigators to identify patients with unilateral otolith impairments. This research has suggested that patients with unilateral otolith impairments perform worse than normal healthy controls on measures of postural stability. It is not yet known if patients with unilateral impairments of the saccule and/or inferior vestibular nerve (i.e., unilaterally abnormal cVEMP) perform differently on measures of postural stability than patients with unilateral impairments of the horizontal SCC (semicircular canal) and/or superior vestibular nerve (i.e., unilateral caloric weakness). Further, it is not known what relationship exists, if any, between otolith system impairment and self-report dizziness handicap. PURPOSE: The purpose of this investigation was to determine the extent to which saccular impairments (defined by a unilaterally absent cVEMP) and impairments of the horizontal semicircular canal (as measured by the results of caloric testing) affect vestibulospinal function as measured through the Sensory Organization Test (SOT) of the computerized dynamic posturography (CDP). A secondary objective of this investigation was to measure the effects, if any, that saccular impairment has on a modality-specific measure of health-related quality of life. RESEARCH DESIGN: A retrospective cohort study. Subjects were assigned to one of four groups based on results from balance function testing: Group 1 (abnormal cVEMP response only), Group 2 (abnormal caloric response only), Group 3 (abnormal cVEMP and abnormal caloric response), and Group 4 (normal control group). STUDY SAMPLE: Subjects were 92 adult patients: 62 were seen for balance function testing due to complaints of dizziness, vertigo, or unsteadiness, and 30 served as controls. INTERVENTION: All subjects underwent videonystagmography or electronystagmography (VNG/ENG), vestibular evoked myogenic potentials (VEMPs), self-report measures of self-perceived dizziness disability/handicap (Dizziness Handicap Inventory), and tests of postural control (Neurocom Equitest). DATA COLLECTION AND ANALYSIS: Subjects were categorized into one of four groups based on balance function test results. All variables were subjected to a multifactor analysis of variance (ANOVA). The Dizziness Handicap Inventory (DHI) total scores and equilibrium scores served as the dependent variables. RESULTS: Results showed that patients with abnormal unilateral saccular or inferior vestibular nerve function (i.e., abnormal cVEMP) demonstrated significantly impaired postural control when compared to normal participants. However, this group demonstrated significantly better postural stability when compared to the group with abnormal caloric responses alone and the group with abnormal caloric responses and abnormal cVEMP results. Patients with an abnormal cVEMP did not differ significantly on the DHI compared to the other two impaired groups. CONCLUSIONS: We interpret these findings as evidence that a significantly asymmetrical cVEMP in isolation negatively impacts performance on measures of postural control compared to normal subjects but not compared to patients with significant caloric weaknesses. However, patients with a unilaterally abnormal cVEMP do not differ from patients with significant caloric weaknesses in regard to self-perceived dizziness handicap.

Patterns of abnormality in cVEMP, oVEMP, and caloric tests may provide topological information about vestibular impairment.

BACKGROUND: The cervical vestibular evoked myogenic potential (cVEMP) is recorded from the sternocleidomastoid muscle (SCM) and represents a stimulus-evoked attenuation of electromyographic (EMG) activity following activation of the saccule and inferior vestibular nerve. In addition to the cVEMP, it is possible to record a biphasic response from the infraorbital region following stimulation that is identical to that used to record the cVEMP. This response is known as the ocular VEMP (oVEMP). The peripheral vestibular origins of the oVEMP elicited with air conduction remain controversial as some investigators argue the response originates from the saccule and others argue that the response emanates from the utricle. We review several lines of evidence and present several case studies supporting the contention that the oVEMP to air conduction stimulation derives its peripheral origins predominantly from the utricle and superior vestibular nerve. PURPOSE: To review the current evidence regarding the peripheral origins of the oVEMP. Further, a purpose of this report is to present case studies illustrating that the cVEMP and oVEMP to air conduction stimulation may vary independently of one another in patients with peripheral vestibular system impairments. RESEARCH DESIGN: A collection of case studies illustrating three common patterns of abnormality observed in patients complaining of vertigo seen in a tertiary care referral center. STUDY SAMPLE: Retrospective analysis of data from three patients complaining of dizziness and/or vertigo who have undergone vestibular function tests. RESULTS: Each case report illustrates a different pattern of abnormality of caloric, cVEMP, and oVEMP tests results from three patients with a vestibular nerve section, superior vestibular neuritis, and Ménière's disease, respectively. CONCLUSIONS: We have shown that the cVEMP and oVEMP can vary independent of one another, and in that way, provide topological information about the sites of impairment. We feel that, with caloric, oVEMP, and cVEMP tests, it is possible to augment the diagnostic information we are able to provide regarding the location, or locations, of vestibular system impairment. These findings suggest that air conduction oVEMPs measure a part of the peripheral vestibular system different from that measured by cVEMPs, perhaps the utricle, and similar to that measured by caloric testing, the superior portion of the vestibular nerve.

Case Study: Depersonalization and Vestibular Impairment.

BACKGROUND: We describe herein the case of a patient whose primary complaints were episodic vertigo and "depersonalization," a sensation of detachment from his own body. PURPOSE: This case study aims to further clinical knowledge and insight into the clinical evaluation of vertiginous patients with complaints of depersonalization. RESEARCH DESIGN: This is a case study. DATA COLLECTION AND ANALYSIS: A retrospective chart review of vestibular function testing done on a vertiginous patient with complaints of depersonalization was performed. RESULTS: Vestibular function testing revealed absent cervical and ocular vestibular evoked myogenic potentials on the left side with normal vHIT or video Head Impulse Test, videonystagmography, and rotational chair results, suggesting peripheral vestibular impairment isolated to the left saccule and utricle. CONCLUSION: The otolith end organ impairment explains the patient's postural deviation to the left side during attempts to ambulate. We recommend that clinicians should be attentive to patient complaints of depersonalization and perform vestibular evoked myogenic potential testing to determine whether evidence of at least a unilateral peripheral otolith end organ impairment exists.

Transforming superior canal dehiscence to chronic subjective dizziness: from SCD to CSD.

Patients presenting with chronic dizziness and no identifiable vestibular impairments have been described as having "extravestibular" symptoms, or "psychogenic dizziness." In 2005, Staab and Ruckenstein described a syndrome they referred to as "chronic subjective dizziness" (CSD), which characterized this concept more clearly. According to Staab and Ruckenstein (2003), the primary physical symptoms of CSD are continual nonvertiginous dizziness or subjective imbalance that persists for 3 mo or longer. Patients suffering from CSD often describe their dizziness as a rocking or swaying when sitting or standing. This case study describes a 41-yr-old female who originally presented with complaints of noise-induced vertigo. The patient's history, imaging studies, and balance function examinations led to the diagnosis of a right-sided superior canal dehiscence (SCD). After surgical repair of the dehiscence, the quantitative electrophysiological tests returned to normal. However, the patient's scores on measures of anxiety, depression, and self-perceived dizziness handicap increased significantly postoperatively. This case illustrates the transformation of a peripheral end-organ impairment (i.e., SCD) into a psychiatric condition (i.e., CSD).

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.

Short Communication: The Belly-Tendon Derivation Yields Superior Ocular Vestibular Evoked Myogenic Potential Amplitudes in a Normal Pediatric Sample.

Purpose The purpose of the investigation was to determine whether the "belly-tendon" electrode derivation produced ocular vestibular evoked myogenic potentials (oVEMPs) in children that were superior to those recorded with the infraorbital-chin electrode derivation. Method This was a prospective observational study using a sample of convenience at a tertiary care medical center. Subjects were 13 children between the ages of 5 and 12 years. We compared the latency of the N1 wave and the N1-P1 peak-to-peak amplitude for the belly-tendon electrode derivation to the infraorbital-chin electrode derivation. Results The belly-tendon electrode derivation was associated with superior N1-P1 amplitudes compared to the infraorbital-chin electrode derivation. However, the large amplitude was also associated with greater variability compared to the infraorbital-chin derivation. There were no significant electrode derivation-based differences in N1 latency. Additionally, there was no predictable relationship between age and oVEMP amplitude. Conclusion As shown previously in adults, the belly-tendon electrode derivation produces significantly larger oVEMP amplitudes compared to the infraorbital-chin electrode derivation.