Caloric test versus rotational sinusoidal harmonic acceleration and step-velocity tests in patients with and without suspected peripheral vestibulopathy

Comparative utility of vestibular function tests in patients with peripheral and central vestibular dysfunction

Background

Bithermal caloric irrigation, video head impulse test (vHIT), and rotational testing are commonly used to assess peripheral vestibular function, but the relative clinical utility of each test in differentiating patients with peripheral vestibulopathy is debated.

Objectives

To determine whether (1) the combination of two or more vestibular tests enhances diagnostic utility over a single test; (2) abnormal test results on vestibular tests correlate with one another.

Methods

Retrospective analysis of data collected from multidisciplinary vestibular clinics at two academic medical centers from 2016 to 2022.

Results

150 patients (54.10 ± 15.09 years, 88 females) were included. No individual test was significantly better at predicting the presence of peripheral vestibular damage (p > 0.05). vHIT test results improved significantly when combined with either the caloric test (p = 0.007) or rotary chair test (p = 0.039). Caloric and rotational testing had high sensitivity (74.65% and 76.06%, respectively) and specificity (83.54% and 78.48%, respectively). vHIT demonstrated excellent specificity (89.87%) but poor sensitivity (47.89%). Caloric, vHIT, and rotary chair tests results did not correlate with one another (p > 0.05).

Conclusions

Vestibular function tests have comparable diagnostic utility, yet each offers unique advantages. Caloric and rotational testing may be best suited for screening peripheral damage and vHIT may function ideally as a confirmatory test.

Dynamic change of vestibular function and the long-term prognosis of vestibular neuritis

AIM

To comprehensively evaluate the dynamic change of vestibular function during long-term follow-up of vestibular neuritis, as well as the co-relationship with the outcomes of vestibular neuritis (VN), which provides the recommendations for vestibular function tests during the course of VN.

METHODS

A prospective cohort study was conducted on 16 patients with acute VN. Caloric test, vHIT, rotatory chair tests, VEMP, dizziness handicap inventory (DHI) score, and dynamic dizzy scales (VAS-DD) was first performed within 7 days of neuritis onset, which were further re-evaluated during the 6-12 months of follow-up. The dynamic changes on multiple objective vestibular examinations were analyzed during the acute and recovery stage of VN. We further evaluated the co-relationship between the vestibular dysfunction scales and the prognosis of VN.

RESULTS

In more than 6 months of follow-up, 44% of the ultralow frequency, 94% of the low-to-mid frequency, and 44% of the high-frequency function of the horizontal semicircular canal returned to normal (p < 0.05). The change degree in symmetry of the rotatory chair test was correlated with the gain of the horizontal semicircular canal on the vHIT and the unilateral weakness (UW) value on the caloric test (p < 0.05). The change in DHI score was correlated with the phase; change in VAS-DD level correlated with the symmetry and TC of the rotatory chair test at VN recovery stage (p < 0.05). There was no significant correlation between the change in DHI score or change in VAS-DD and the degree of vestibular function recovery (p > 0.05).

CONCLUSION

In general, vestibular function improved during the course of VN. The rotatory chair test can be used to evaluate the overall function of the vestibular system and the compensatory state in patients with VN.

The prevalence of isolated otolith dysfunction in a local tertiary hospital

OBJECTIVE

Patients with dizziness may present with symptoms of tilting, swaying, rocking, floating or with disequilibrium. This may be suggestive of an isolated otolithic dysfunction yet, there is little emphasis on this emerging clinical entity. To characterize and describe the prevalence of isolated otolith dysfunction in a local tertiary hospital and correlate them with clinical diagnosis.

METHODOLOGY

Retrospective medical chart review of patients who presented with dizziness to the specialist outpatient Otolaryngology clinic, who required vestibular laboratory investigation.

RESULTS

Of the 206 patients, more than half of them (52.4%) fulfilled the criteria for either probable or definite isolated otolith dysfunction. When there are clinical symptoms of otolith dysfunction reported, there is a 1.62 odds of a remarkable laboratory otolith finding. The most common clinical finding was "no clear diagnosis" (65.5%) followed by Vestibular Migraine (13.6%).

CONCLUSION

The prevalence of isolated otolith dysfunction is quite high. Laboratory tests of otolith function should be performed more routinely. This can be done in a sequential way to optimize cost effectiveness in countries with no insurance reimbursement. Prospective cohort studies on isolated otolith dysfunction, will lay the groundwork for achieving diagnostic consensus and formulating rehabilitation plans to aid this group of patients.

The Outpatient Approach to Dizziness

The evaluation of the dizzy patient is complicated by many common pitfalls. The patient's description of symptoms and the standard neurologic examination are often nonspecific or unrevealing, and neuroimaging is most often normal. Over the past several years, research has demonstrated that a refocusing of history taking results in more reliable and diagnostically helpful information. This can guide a targeted expansion of the exam, often with an emphasis on eye movements.

Update on current diagnosis and treatment of vestibular neuritis

Vertigo is the sensation of self-motion of the head or body when no self-motion is occurring or the sensation of distorted self-motion during an otherwise normal head movement. Representative peripheral vertigo disorders include benign paroxysmal positional vertigo, Ménière disease, and vestibular neuritis. Vestibular neuritis, also known as vestibular neuronitis, is the third most common peripheral vestibular disorder after benign paroxysmal positional vertigo and Ménière disease. The cause of vestibular neuritis remains unclear. However, a viral infection of the vestibular nerve or ischemia of the anterior vestibular artery is known to cause vestibular neuritis. In addition, recent studies on immune-mediated mechanisms as the cause of vestibular neuritis have been reported. The characteristic clinical features of vestibular neuritis are abrupt true-whirling vertigo lasting for more than 24 hours, and no presence of cochlear symptoms and other neurological symptoms and signs. To accurately diagnose vestibular neuritis, various diagnostic tests such as the head impulse test, bithermal caloric test, and vestibular-evoked myogenic potential test are conducted. Various treatments for vestibular neuritis have been reported, which are largely divided into symptomatic therapy, specific drug therapy, and vestibular rehabilitation therapy. Symptomatic therapies include generalized supportive care and administration of vestibular suppressants and antiemetics. Specific drug therapies include steroid therapy, antiviral therapy, and vasodilator therapy. Vestibular rehabilitation therapies include generalized vestibular and customized vestibular exercises.

Initial Degree of Spontaneous Nystagmus Affects the Length of Hospitalization of Patients With Vestibular Neuritis

OBJECTIVE

To assess factors predicting vestibular neuritis (VN) prognosis at an early stage.

STUDY DESIGN

Retrospective chart review.

SETTING

University hospital.

PATIENTS

Sixty-five patients with VN, between 2014 and 2018.

INTERVENTIONS

Bithermal caloric test, rotatory chair test, subjective visual horizontal and vertical, cervical visual myogenic evoked potential test, and visual head impulse test (vHIT).

MAIN OUTCOME MEASURES

Hospitalization duration.

RESULTS

The mean hospitalization duration was 4.6 ± 1.4 days. Mean caloric weakness was 65.5 ± 20.6%. For the vHIT, gain in both anterior and horizontal semicircular canal (SCC) was statistically significantly different between the lesion and intact sides (p < 0.001). Backward conditional regression analysis revealed that a higher degree of spontaneous nystagmus (SN) (EXP[B] = 1.104, 95% confidence interval [CI] = 1.012-1.204, p = 0.026), and a lower caloric paresis (CP) value (EXP(B) = 1.033, 95% CI = 1.000-1.075, p = 0.047) were associated with 5 days or more of hospitalization. The cut-off value of SN was 12.05 degrees/s for increased hospital stay. Four weeks after discharge from hospital, five patients (8.9%) had persistent SN, and 19 (33.9%) and 28 (50.0%) had a positive HIT and nystagmus during head-shaking, respectively. Patients with persistent nystagmus at 1 month had more severe initial SN (p < 0.05).

CONCLUSION

Only the degree of SN at the initial evaluation affected both the hospitalization period and the bed-side examination results at 1 month after discharge in patients with VN.

Clinician Use and Payments by Medical Specialty for Audiometric and Vestibular Testing Among US Medicare Beneficiaries

Importance

Variations in diagnostic test use may indicate that there are opportunities for quality improvement in vestibular health care. To date, the extent to which clinician acquisition of tests varies nationwide by region and specialty of the clinician is unknown.

Objective

To quantify variation in clinician use and payments for audiograms and vestibular tests across all geographic regions of the United States and by specialty of practice.

Design, Setting, and Participants

This cross-sectional study used a population-based sample of 1 307 887 audiovestibular test claims from fee-for-service Medicare beneficiaries aged 65 years or older in the Medicare Provider Utilization and Payment Public Use File from January 1 through December 31, 2014. The analysis was completed from January 2 through June 1, 2019.

Exposures

Diagnostic audiograms, caloric testing, and rotary chair testing.

Main Outcomes and Measures

Test utilization was analyzed by hospital referral region, medical specialty, and total payments.

Results

In 2014, clinicians performed 1 213 328 audiograms, 317 880 caloric tests (ie, single caloric irrigations), and 62 779 rotary chair tests, for a total of $38 647 350.21 in Medicare payments from the Centers for Medicare & Medicaid Services. No patient or clinician demographic characteristics were available. Across health care referral regions, rates of testing per 100 000 beneficiaries varied from 166 to 12 021 for audiograms, 15 to 4271 for caloric tests, and 13 to 3556 for rotary chair tests between the lowest-use and highest-use regions. Most audiograms and caloric tests were billed by audiologists (797 957 audiograms [65.8%]; 112 485 caloric tests [35.4%]) and otolaryngologists (376 728 audiograms [31.0%]; 70 567 caloric tests [22.2%]). In contrast, primary care physicians (18 933 [30.2%]) and neurologists (15 254 [24.3%]) billed the largest proportion of rotary chair tests compared with other specialists, including audiologists (7253 [11.6%]) and otolaryngologists (6464 [10.3%]).

Conclusions and Relevance

Substantial geographic and clinician-level variation may have been observed in use of audiovestibular tests. Quality improvement efforts in vestibular health care may need to target a range of clinicians, including primary care physicians to be successful.

The Relationship Between Rotary Chair and Video Head Impulse Testing in Children and Young Adults With Cochlear Implants

Purpose Conflicts among video head impulse testing (vHIT) and rotary chair have occurred; therefore, the purpose of this study was to determine the relationship between rotary chair and vHIT outcome parameters to understand when these two tests disagree and determine if one or both test outcomes are needed in children. Method Data from 141 child and young adult subjects (73 males, 68 females, M _age = 15 years, range: 6-35) were retrospectively reviewed. Of those, 56 had a cochlear implant and 85 were normal controls. All subjects completed rotary chair and vHIT, which were categorized as (a) normal vestibular function, (b) unilateral vestibular loss, or (c) bilateral vestibular loss. vHIT tracings were analyzed to determine if gain and corrective saccade velocity, frequency, or latency were helpful parameters for determining vestibular loss. Results Of the 141 subjects, the misclassification rate was 13/141 (9%). All normal control subjects were classified as having normal rotary chair and normal vHIT. In subjects with a cochlear implant (n = 56), the misclassification rate was 13/56 (23%). There were four misclassification patterns. Using rotary chair as the gold standard, receiver operating characteristic analysis revealed optimal cut-points for vHIT gain (< 0.84), corrective saccade frequency (≥ 50%), amplitude (≥ 75°/s), and latency (≤ 320 ms). Using these vHIT cut-points improved the agreement between rotary chair and vHIT, resulting in an overall misclassification rate of 10/141 (7%) and 9/56 (16%) in subjects with a cochlear implant. Conclusions When testing children, caloric testing is often not an option due to tolerability or time. However, discordant results occur between rotary chair and vHIT. These data suggest vHIT is a sufficient first-tier assessment. If abnormal, rotary chair is not necessary. If normal, rotary chair can be helpful for uncovering other indicators of vestibular loss. When interpreting vHIT, including gain and all corrective saccade outcomes may improve sensitivity.

Clinical Practice Guideline: Ménière's Disease

OBJECTIVE

Ménière's disease (MD) is a clinical condition defined by spontaneous vertigo attacks (each lasting 20 minutes to 12 hours) with documented low- to midfrequency sensorineural hearing loss in the affected ear before, during, or after one of the episodes of vertigo. It also presents with fluctuating aural symptoms (hearing loss, tinnitus, or ear fullness) in the affected ear. The underlying etiology of MD is not completely clear, yet it has been associated with inner ear fluid (endolymph) volume increases, culminating in episodic ear symptoms (vertigo, fluctuating hearing loss, tinnitus, and aural fullness). Physical examination findings are often unremarkable, and audiometric testing may or may not show low- to midfrequency sensorineural hearing loss. Conventional imaging, if performed, is also typically normal. The goals of MD treatment are to prevent or reduce vertigo severity and frequency; relieve or prevent hearing loss, tinnitus, and aural fullness; and improve quality of life. Treatment approaches to MD are many and typically include modifications of lifestyle factors (eg, diet) and medical, surgical, or a combination of therapies.

PURPOSE

The primary purpose of this clinical practice guideline is to improve the quality of the diagnostic workup and treatment outcomes of MD. To achieve this purpose, the goals of this guideline are to use the best available published scientific and/or clinical evidence to enhance diagnostic accuracy and appropriate therapeutic interventions (medical and surgical) while reducing unindicated diagnostic testing and/or imaging.

Vestibular testing in children with severe-to-profound hearing loss

Many studies showed that children with sensorineural hearing loss (SNHL) have possible vestibular affection which is related to the severity of cochlear pathology.

OBJECTIVES

this work is designed to evaluate vestibular function in children with congenital severe to profound SNHL and correlate the degree of hearing loss with the results of vestibular tests.

METHODS

this work included 52 children divided into two groups; control group consisted of 20 normal hearing children with no vestibular complaints, and study group consisted of 32 children with congenital severe to profound SNHL. All children were submitted to basic audiologic evaluation, combined vestibular evoked myogenic potentials, sinusoidal harmonic acceleration test (SHA) of rotatory chair test.

RESULTS

all children in the control group had normal oVEMP and cVEMPs results while abnormal cVEMPs and oVEMPs results were found in 89% and 96.9% of the tested ears of the study group respectively. Sinusoidal harmonic acceleration test results were normal in control group with significant reduction in gain, phase lead and higher level of asymmetry in 50% of the children in study group. There was a significant relation between the degree of hearing loss and the cVEMPs, oVEMPs abnormalities, while SHA test results showed no such relationship.

CONCLUSION

There is an evident vestibular abnormalities in children with severe to profound sensorineural hearing loss as revealed by the rotatory chair testing and VEMPs recordings. Vestibular assessment is very important in such group as it has an impact on their rehabilitation plan.

Acute vestibular asymmetry disorder: a new disease entity in acute vestibular syndrome?

BACKGROUND

Acute vestibular syndrome (AVS) is characterized by the rapid onset of vertigo, nausea, vomiting and gait unsteadiness, which lasts for days.

AIMS/OBJECTIVES

We report cases as acute vestibular asymmetry disorder (AVAD), with presentations that mimic vestibular neuritis (VN) but without central lesions.

MATERIALS AND METHODS

We retrospectively reviewed records of patients presenting with acute spontaneous vertigo lasting more than 24 h from January 2011 to June 2016. Among 341 patients, five showed different findings that did not indicate either VN or stroke. We analyzed the clinical features and vestibular assessments of these patients.

RESULTS

All five patients showed spontaneous nystagmus continuing for several days. However, head impulse tests (HITs) did not reveal a corrective saccade. Brain magnetic resonance imaging showed no abnormal lesions. The bithermal caloric test revealed directional preponderance without canal paresis. Finally, the slow harmonic test of the rotatory chair revealed unilateral high gain and phase within the normal range, but a significantly asymmetric response was observed. No patients showed recurrence during follow-up.

CONCLUSIONS AND SIGNIFICANCE

Our study suggests that a normal HIT in AVS is not always a dangerous sign indicating an acute stroke. From our observations, we propose that AVAD would be a new disease entity within AVS.

Effects of motion sickness severity on the vestibular-evoked myogenic potentials

BACKGROUND

Motion sickness is a common debilitating condition associated with both actual and perceived motion. Despite the commonality, little is known about the underlying physiological mechanisms. One theory proposes that motion sickness arises from a mismatch between reality and past experience in vertical motions. Physiological tests of the vestibular system, however, have been inconclusive regarding the underlying pathogenesis. Cervical vestibular-evoked myogenic potentials (cVEMPs) arise from the saccule, which responds to vertical motion. If vertical motion elicits motion sickness, the cVEMP should be affected.

PURPOSE

The purpose of this investigation was to determine if cVEMP characteristics differ among individuals with a range of motion sickness susceptibility from negligible to severe. The hypothesis was that individuals with high susceptibility would have larger cVEMP amplitudes and shorter cVEMP latencies relative to those who are resistant to motion sickness.

RESEARCH DESIGN

The study had two parts. The first was quasi-experimental in which participants comprised three groups based on susceptibility to motion sickness (low, mild-moderate, high) as identified on the short version of the Motion Sickness Susceptibility Questionnaire (MSSQ-S). The second part of the study was correlational and evaluated the specific relationships between the degree of motion sickness susceptibility and characteristics of the VEMPs.

STUDY SAMPLE

A total of 24 healthy young adults (ages 20-24 yr) were recruited from the university and the community without regard to motion sickness severity.

DATA COLLECTION AND ANALYSIS

Participants took the MSSQ-S, which quantifies susceptibility to motion sickness. The participants had a range of motion sickness susceptibility with MSSQ raw scores from 0.0-36.6, which correspond to percent susceptibility from 0.0-99.3%. VEMPs were elicited by 500 Hz tone-bursts monaurally in both ears at 120 dB pSPL. MSSQ-S percent scores were used to divide the participants into low, mild-moderate, and high susceptibility groups. A fixed general linear model with repeated-measures analysis of variance tested cVEMP characteristics for the susceptibility groups (between participants) and ears (within participants). A univariate analysis of variance tested the cVEMP interaural amplitudes across groups. The second analysis was a regression of the severity of motion sickness in percent on cVEMP characteristics. Significance was defined as p < 0.05.

RESULTS

Participants in the high susceptibility group had significantly higher cVEMP amplitudes than those in the low susceptibility group. cVEMP amplitudes did not differ between ears, and latencies did not differ between the two groups or between ears. Regression analysis on MSSQ-S percent susceptibility by VEMP amplitudes revealed a best-fit cubic function in both ears, with r(2) values of more than 42%. The interaural asymmetry ratio was negatively associated with motion sickness susceptibility (r(2) = 0.389).

CONCLUSIONS

The current study is the first to report that greater susceptibility to motion sickness is associated with larger cVEMP amplitudes and lower interaural cVEMP asymmetries. Larger interaural asymmetries in cVEMPs did not promote motion sickness susceptibility. The cVEMP findings implicate the saccule and its neural pathways in the production of motion sickness and are consistent with the theory that vertical motions elicit motion sickness. Motion sickness susceptibility may contribute to the variability in normative cVEMP amplitudes.

Determination of the time course of caloric nystagmus in patients with spinocerebellar degeneration using caloric step stimulus procedure

CONCLUSIONS

The step stimulus procedure can provide information on the time course of the vestibulo-ocular reflex. Spinocerebellar degeneration and aging seem to shorten the time constant of the onset of the vestibulo-ocular reflex, causing a rapid rise up. Failure of the central processing of velocity storage might contribute to this rapid rise up.

OBJECTIVES

The aim of this study is to evaluate the time course characteristics of the vestibulo-ocular reflex in patients with spinocerebellar degeneration.

METHODS

Ten patients (20 ears) and 22 healthy subjects (30 ears) underwent caloric test using the step stimulus procedure. We evaluated the time course of caloric VOR and calculated the parameters of the time constant of an activation and adaptation response. We compared between the control and SCD groups to elucidate the time course characteristics of caloric VOR in patients with SCD.

RESULTS

Spinocerebellar degeneration seems to shorten the time constant of the activation response by caloric irrigation with 20 °C, 7l/min air. However, aging also possibly contributes to this shortening. No change was observed in the time constant of the adaptation response.

Can the Video Head Impulse Test Define Severity of Bilateral Vestibular Hypofunction?

OBJECTIVE

The objective of the study was to compare rotary chair and video head impulse test (vHIT) findings in patients with bilateral vestibular hypofunction (BVH) to determine whether vHIT can: 1) define severity of BVH and 2) accurately predict rotary chair findings in patients with BVH.

STUDY DESIGN

Retrospective chart review.

SETTING

Research hospital.

PATIENTS

Twenty subjects with bilateral vestibular hypofunction as assessed by rotary chair.

INTERVENTION

Rotary chair and vHIT.

MAIN OUTCOME MEASURES

The main outcome measures were rotary chair phase, gain, and symmetry and vHIT vestibulo-ocular reflex (VOR) gain. Rotary chair and vHIT results were assessed and subjects were stratified into groups according to the severity of their vestibular hypofunction. For rotary chair, subjects were classified as mild, moderate, or severe BVH. For vHIT, subjects were classified as normal, unilateral, or bilateral.

RESULTS

Average lateral canal vHIT VOR gain: 1) significantly increased as severity of BVH decreased, and 2) demonstrated a significant and positive, linear relationship with rotary chair gains. vHIT was in disagreement with rotary chair in the classification of five subjects, which could be due to right-left asymmetry of BVH.

CONCLUSION

vHIT can serve as an initial tool for identifying patients with BVH. Lower vHIT gains are consistent with having severe BVH. There was disagreement between vHIT and rotary chair, though not for any patients with severe BVH. Compared with rotary chair, the clinical gold standard for identifying BVH, vHIT possesses 100% sensitivity for excluding severe BVH when average vHIT gains are greater than 0.46.

Comparison of three diagnostic tests in detecting vestibular deficit in patients with peripheral vestibulopathy

OBJECTIVES

This study aimed to evaluate the results of the video head impulse test and of the caloric and rotatory chair tests in patients with dizziness. Agreement between test results was assessed and the best protocol for detecting peripheral vestibulopathy was identified.

METHODS

Participants comprised 116 patients, 75 with a peripheral vestibulopathy and 41 with non-peripheral vestibulopathy. The main outcome measures were classified as normal or abnormal according to our laboratory data.

RESULTS

Agreement between tests was low. Vestibulopathy testing that required all three results to be abnormal had a sensitivity of 0.547, a specificity of 0.878, and positive and negative predictive values of 0.891 and 0.514, respectively. Vestibulopathy testing that required just one result to be abnormal had a sensitivity of 0.933, a specificity of 0.292, and positive and negative predictive values of 0.701 and 0.705, respectively.

CONCLUSION

In peripheral vestibulopathy, there was weak concordance in the assessment of horizontal semicircular canal function among the different tests. However, the video head impulse test had sufficient statistical power to be recommended as the first-line test.

The dissociation of video head impulse test (vHIT) and bithermal caloric test results provide topological localization of vestibular system impairment in patients with "definite" Ménière's disease

PURPOSE

We report 3 patients with Ménière's disease and describe how the combination of audiometry, video head impulse testing, and caloric results may prove helpful in the diagnosis of Ménière's disease.

METHOD

Three patients with "definite" Ménière's disease were evaluated in a tertiary care medical center. Each patient underwent videonystagmography, horizontal canal video head impulse testing, and audiometry.

RESULTS

All 3 patients demonstrated moderate, flat, sensorineural hearing losses; significant caloric asymmetries; and bilaterally normal video head impulse testing. This pattern of findings suggests differential preservation of high-frequency function (video head impulse testing) with impairment of low-frequency function (unilaterally abnormal caloric test results) in these patients.

CONCLUSION

Ipsilesional abnormal caloric testing in the presence of normal video head impulse testing is a pattern of findings observed in a cohort of patients who have "definite" Ménière's disease.

Vibration-induced nystagmus after acute peripheral vestibular loss: comparative study with other vestibule-ocular reflex tests in the yaw plane

OBJECTIVE

To validate the role of vibration-induced nystagmus (VIN) detecting vestibular asymmetry by comparing several vestibulo-ocular reflex (VOR) parameters in the yaw plane.

STUDY DESIGN

Prospective validation study for diagnostic test.

SETTING

Tertiary referral center.

PATIENTS

Seventy-four patients with unilateral vestibular loss of acute onset without a history of fluctuating vestibular function and 24 healthy volunteers.

INTERVENTION

Spontaneous nystagmus, head-shaking nystagmus (HSN), and VIN using a 100 Hz handheld vibrator were recorded using a videonystagmography system. Canal paresis on the caloric test and the time constant (TC) on the step velocity test were examined as parameters of the laboratory test.

MAIN OUTCOME MEASURES

Correlation analysis between horizontal VOR parameters was performed. Receiver operating characteristic (ROC) curves of these parameters were plotted, and the area under the ROC curve (AUC) was compared according to the lower limiting value of TC on step velocity test as well as the presence of unilateral vestibular loss.

RESULTS

VIN was observed in 64 (86%) of 74 patients, and it was directed toward the contralesional side in 98%. VIN showed a significant positive correlation with the canal paresis (r=0.416, p<0.001) and a negative correlation with the TC (r=-0.351, p<0.005). ROC curves of several VOR parameters were compared according to the presence of unilateral vestibular loss. The AUC of VIN was 0.882, and the cutoff intensity of VIN was 2.5 degrees per second. The AUCs of the HSN and spontaneous nystagmus were 0.774 and 0.661, respectively.

CONCLUSION

The lateralization value of VIN was comparable with caloric test and superior to HSN. VIN is a useful vestibular test detecting vestibular asymmetry in the evaluation of dizziness.

Clinical usefulness of the rotatory, caloric, and vestibular evoked myogenic potential test in unilateral peripheral vestibular pathologies

OBJECTIVE

The aim of this study was to investigate the diagnostic capacity of three different rotatory tests, and to investigate the clinical effectiveness of the caloric, rotatory, and vestibular evoked myogenic potential (VEMP) test.

DESIGN AND STUDY SAMPLE

Several rotatory tests--sinusoidal harmonic acceleration test (SHAT), pseudorandom rotation test (PRRT), velocity step test (VST)--and a caloric and a VEMP test, were given to 77 patients (mean age 52 years) with a unilateral peripheral vestibular pathology, and 80 control subjects (mean age 48 years).

RESULTS

For the rotatory test, the highest diagnostic capacity was obtained with the 0.01 Hz SHAT frequency, followed by 0.1 and 0.05 Hz. A higher diagnostic accuracy was reached for the caloric and VEMP test. The caloric test demonstrated high sensitivity and specificity values, but the 0.01 Hz SHAT rotation appeared more sensitive, and the VEMP more specific, than the caloric test.

CONCLUSION

A selection of the 0.01, 0.05, and 0.1 Hz SHAT rotations is suggested as the most ideal rotatory test protocol, and a combination of rotatory, caloric, and VEMP testing will result in a more complete examination of our vestibular system.

Effect of cupula shrinkage on the semicircular canal activity

CONCLUSION

With half-sized cupula, the semicircular canal nerve potentials decreased under slow stimulus, thus potentially leading to reduced caloric response. This also suggests that shrunken cupula may cause dizziness because of its hypermobility.

OBJECTIVES

To examine the physiological effect of half-sized cupula on the semicircular canal nerve potential.

METHODS

The isolated cupula of the bullfrog was sectioned in half with fine scissors and was replaced on the crista. Mechanical endolymphatic flow and slow and fast stimuli were delivered and the evoked action potentials were recorded.

RESULTS

The cupula was successfully sectioned in half and was replaced on the crista. With the half-sized cupula, the action potentials became smaller under slow stimulus than under fast stimulus.