What is the potential clinical utility of vHIT when assessing adult patients with dizziness?

Clinical characteristics of patients with dizziness/vertigo showing a dissociation between caloric and video head impulse test results

ObjectiveTo explore the clinical characteristics of patients with dizziness/vertigo who showed a dissociation between the results of the caloric test and video head impulse test (vHIT).MethodsA total of 327 patients who complained of dizziness/vertigo were continuously included. All patients underwent both the horizontal vHIT (h-vHIT) and caloric tests. Of the 327 patients, 69 patients showed a dissociation between the results of the two tests, 4 patients were excluded because the interval between the two tests exceeded 7 days. Finally, 65 patients were included in the analysis.ResultsAmong the 65 patients, 55 (84.6%) patients showed a positive caloric test (+) with a negative h-vHIT (-), and 10 (15.4%) patients showed a negative caloric test (-) with a positive h-vHIT (+). Peripheral and central lesions were identified in 50 (90.9%) and 5 (9.1%) patients, respectively, in the caloric test (+)/h-vHIT (-) group; and central lesions were found in 6 (60%) patients in caloric test (-)/h-vHIT (+) group. The etiologies were unilateral peripheral vestibular dysfunction (n = 25), Meniere's disease (MD, n = 10), sudden hearing loss with vertigo (SHLV, n = 7), benign paroxysmal positional vertigo (n = 5), vestibular neuritis (n = 2), autoimmune inner ear disease (n = 1), vestibular migraine (VM, n = 3), multiple sclerosis (n = 1), and multiple system atrophy (n = 1) in the caloric test (+)/h-vHIT (-) group, which were SHLV (n = 3), MD (n = 1), VM (n = 1), episodic ataxia type 2 (n = 1), cerebellopontine angle tumor (N = 1), Parkinson's disease (n = 1), Persistent postural perceptual dizziness (n = 1), and posterior circulation ischemia (n = 1) in the caloric test (-)/h-vHIT (+) group.ConclusionDissociation between the results of caloric test and h-vHIT is not uncommon. A positive caloric test with a negative h-vHIT occurred more frequently, and these patients mostly had peripheral vestibular lesions; while a negative caloric test with a positive h-vHIT was unusual, these patients had both peripheral and central lesions.

Evaluation of Semicircular Canal Function Using Video Head Impulse Test in Patients With Peripheral Vestibular Disorders Without Nystagmus

Objectives This study aims to evaluate semicircular canal function using video head impulse test (vHIT) in patients with peripheral vestibular disorders without nystagmus. Methods Patients who underwent vHIT were enrolled in this study, and the proportion of abnormal findings on vHIT in patients without nystagmus was investigated. In addition, the results of vestibular testing were investigated in cases in which both vHIT and caloric testing were performed in patients without nystagmus. Results Forty-six patients (23.4%) of 197 patients who had no abnormal findings on the nystagmus tests, including the gaze nystagmus test, positional nystagmus test, and positioning nystagmus test, showed dysfunction in at least one semicircular canal on vHIT. The most frequent diagnosis was vestibular schwannoma (14/46, 30.4%), and cases with bilateral vestibular dysfunction were also included (12/46, 26.1%). A disorganized pattern of catch-up saccade was observed more frequently in patients with subjective symptoms of dizziness/vertigo compared to those without subjective symptoms. Although the sensitivity of vHIT was low compared to caloric testing, vHIT could detect isolated vertical canal dysfunction not detected by caloric testing. Conclusions vHIT is considered to be a useful test for patients without nystagmus, as vHIT could detect abnormalities in approximately one-quarter of patients without nystagmus. vHIT is considered to be one of the first tests to be performed following nystagmus testing, including the gaze nystagmus test, the positional nystagmus test, and the positioning nystagmus test. On the other hand, there are some cases in which vHIT shows no abnormality while caloric testing shows canal paresis. It is necessary to perform vHIT, bearing in mind that there are abnormalities that cannot be detected by vHIT alone.

Video head impulse test in stroke: a review of published studies

Accurate and timely diagnosis of posterior circulation stroke in patients with acute dizziness is a challenge that can lead to misdiagnosis and significant harm. The present review sought to identify and describe published research on the clinical application of vHIT in posterior circulation stroke. vHIT, a portable device, has gained prominence in evaluating peripheral vestibular disorders and offers potential applications in diagnosing neurological disorders, particularly posterior circulation stroke. Several studies have shown that vHIT can differentiate between stroke and vestibular neuritis based on VOR gain values, with high sensitivity and specificity. The manuscript also discusses vHIT's performance in differentiating between types of posterior circulation stroke, such as PICA, AICA, and SCA strokes. While vHIT has demonstrated promise, the review emphasizes the need for further research to validate its use as a tool to rule out stroke in acute dizziness patients in the emergency department. In conclusion, the manuscript underscores the potential of vHIT as a valuable addition to the diagnostic arsenal for acute dizziness, particularly in the context of posterior circulation stroke. It calls for further research and wider adoption of vHIT in clinical settings to improve patient care and reduce unnecessary costs associated with misdiagnoses.

Insights Into Vestibulo-Ocular Reflex Artifacts: A Narrative Review of the Video Head Impulse Test (vHIT)

Video head impulse test (vHIT) artifacts are defined as spurious elements or disturbances in the recorded data that deviate from the true vestibulo-ocular reflex response. These artifacts can arise from various sources, encompassing technological limitations, patient-specific factors, or environmental influences, introducing inaccuracies in vHIT outcomes. The absence of standardized criteria for artifact identification leads to methodological heterogeneity. This narrative review aims to comprehensively examine the challenges posed by artifacts in the vHIT. By surveying existing literature, the review seeks to elucidate the multifaceted nature of artifacts arising from technological, patient-related, evaluator-related, and environmental factors.

Comparison of Asymmetry between Perceptual, Ocular, and Postural Vestibular Screening Tests

BACKGROUND

A better understanding of how vestibular asymmetry manifests across tests is important due to its potential implications for balance dysfunction, motion sickness susceptibility, and adaptation to new environments.

OBJECTIVE

We report the results of multiple tests for vestibular asymmetry in 32 healthy participants.

METHODS

Asymmetry was measured using perceptual reports during unilateral centrifugation, oculomotor responses during visual alignment tasks, vestibulo-ocular reflex gain during head impulse tests, and body rotation during stepping tests.

RESULTS

A significant correlation was observed between asymmetries of subjective visual vertical and verbal report during unilateral centrifugation. Another significant correlation was observed between the asymmetries of ocular alignment, vestibulo-ocular reflex gain, and body rotation.

CONCLUSIONS

These data suggest that there are underlying vestibular asymmetries in healthy individuals that are consistent across various vestibular challenges. In addition, these findings have value in guiding test selection during experimental design for assessing vestibular asymmetry in healthy adults.

Diagnostic Value of the Vestibular Autorotation Test in Menière's Disease, Vestibular Migraine and Menière's Disease with Migraine

(1) Background: Vestibular migraine (VM) and Menière's disease (MD) share multiple features in terms of clinical presentations and auditory-vestibular functions, and, therefore, more accurate diagnostic tools to distinguish between the two disorders are needed. (2) Methods: The study was of retrospective design and examined the data of 69 MD patients, 79 VM patients and 72 MD with migraine patients. Five vestibular autorotation test (VAT) parameters, i.e., horizontal gain/phase, vertical gain/phase and asymmetry were subjected to logistic regression. The receiver operating characteristic (ROC) curves were generated to determine the accuracy of the different parameters in the differential diagnosis of MD and VM. (3) Results: Our results showed that the horizontal gain of VAT significantly outperformed other parameters in distinguishing MD and VM. In addition, the sensitivity, specificity and accuracy of the horizontal gain were 95.7%, 50.6% and 71.6%, respectively, for the differentiation between VM and MD. In most MD patients, the horizontal gain decreased in the range of 3-4 Hz, while in most VM patients, horizontal gain increased in the range between 2-3 Hz. More MD with migraine patients had an increased horizontal gain when the frequency was less than 5.0 Hz and had a decreased horizontal gain when the frequency was greater than 5.0 Hz. (4) Conclusion: Our study suggested the VAT, especially the horizontal gain, as an indicator, may serve as a sensitive and objective indicator that helps distinguish between MD and VM. Moreover, VAT, due to its non-invasive and all-frequency nature, might be an important part of a test battery.

[The application value of video head impulse test, caloric test and dizziness handicap inventory in the diagnosis of acoustic neuroma]

Objective:To explore the application value of video head impulse test（vHIT）, caloric test（CT） and the dizziness handicap inventory（DHI） in the diagnosis of acoustic neuroma（AN）, to analyze the correlation between vHIT and CT, and to determine the correlationsof tumor size, vHIT, CT and DHI score. Methods:The clinical data of 24 patients with AN who underwent surgery in our department from January 2019 to January 2022 were analyzed retrospectively, including craniocerebral MRI, vHIT, caloric test and DHI score. All the data were statistically analyzed by GraphPadPrism9.0. Results:There was a significant negative correlation between the UW value of CT and the vestibular eye reflex gain of vHIT（P<0.01, r=-0.62）. The tumor size was significantly correlated with the increase of UW value of CT（P<0.01, r=0.69）, and with the decrease of vestibulo-ocular reflex gain of vHIT（P<0.01, r=-0.53）. The average Dizziness Handicap Inventory score was 8.9±16.2, which was not correlated with tumor size（P>0.05）. Conclusion:Both vHIT and CT can effectively evaluate the vestibular function of patients with AN（and they are complementary）, and they are related to the size of the tumor and have certain value in the diagnosis of acoustic neuroma.

Relationship between spontaneous nystagmus and video Head Impulse Test findings among patients with chronic neurotologic conditions

The vestibulo-ocular reflex (VOR) in neurotologic patients can be evaluated most quickly by spontaneous nystagmus examinations, and the video Head Impulse Test (vHIT) quantitatively evaluates the VOR of the semicircular canals. We aimed to clarify the concordance and discrepancies between spontaneous nystagmus and vHIT findings, to provide guidance on screening vestibular functions by initial spontaneous nystagmus examination then vHIT. We evaluated 169 outpatients by spontaneous nystagmus examination in the dark using a charge-coupled device camera, then by horizontal vHIT the same day. Vestibular loss on vHIT was defined if both reduced VOR gain (<0.8) and corrective saccade were observed. Adjusted logistic regression modelling revealed that differences in right and left VOR gain positively impacted the presence of nystagmus, which suggests lateralised vestibular dysfunction (P<0.05; odds ratio 1.39 [95% confidence interval, 1.1-1.8] per 0.1 increment). When vHIT is regarded as the standard clinical test, the positive predictive value of nystagmus for vestibular loss on vHIT was 44.4%, and the negative predictive value was 93.5%. The adjusted odds ratio of adults ≥65 years old compared to younger patients associated with a discrepancy of nystagmus and vHIT was significant (2.4 [1.1-5.3]). In conclusion, if spontaneous nystagmus is initially observed in patients, further assessment by vHIT could confirm vestibular dysfunction in 40-50% of cases. If no nystagmus is observed, vHIT might also result in a negative finding in >90% of cases. Older adults appear more likely to show discrepancies between nystagmus and vHIT.

Imbalance and dizziness caused by unilateral vestibular schwannomas correlate with vestibulo-ocular reflex precision and bias

Imbalance and dizziness are disabling symptoms for many patients with vestibular schwannomas (VS) but symptom severity typically does not correlate with the vestibulo-ocular reflex (VOR) amplitude-based metrics used to assess peripheral vestibular damage. In this study, we tested the hypothesis that imbalance and dizziness in patients with VS relate to VOR metrics that are not based on response amplitude. Twenty-four patients with unilateral, sporadic VS tumors were studied, and objective (balance) and subjective (dizziness) vestibular dysfunction was quantified. The VOR was tested using two yaw-axis motion stimuli, low-frequency en-bloc sinusoidal, and high-frequency head-on-body impulsive rotations. Imbalance correlated with VOR precision (the inverse of the trial-to-trial variability) and with low-frequency VOR dynamics (quantified with the time constant), and these two metrics were also strongly correlated. Dizziness correlated with the VOR bias caused by an imbalance in static central vestibular tone, but not with dynamic VOR metrics. VOR accuracy (mean response amplitude relative to the ideal response) was not correlated with the severity of imbalance or dizziness or with measures of VOR precision or time constant. Imbalance in patients with VS, therefore, scales with VOR precision and time constant, both of which appear to reflect the central vestibular signal-to-noise ratio, but not with VOR slow-phase accuracy, which is based on the magnitude of the central vestibular signals. Dizziness was related to the presence of a static central tone imbalance but not to any VOR metrics, suggesting that abnormal perception in VS may be affected by factors that are not captured by yaw-axis VOR measurements.NEW & NOTEWORTHY The severity of symptoms associated with unilateral vestibular schwannomas (VS) is poorly correlated with standard yaw-axis vestibulo-ocular reflex (VOR) metrics that are based on response amplitude. In this study, we show that the balance and perceptual dysfunction experienced by patients with VS scales with VOR metrics that capture information about the central signal-to-noise ratio (balance) and central static tone (dizziness), but are not correlated with the VOR gain, which reflects central signal amplitude.

Emerging and distinct video head impulse test responses in elderly with vestibular symptoms

INTRODUCTION

Dizziness has been reported to be the most common symptom in elderly population. Video head impulse test, VHIT, allows clinicians to assess the vestibular function in elderly individuals, during their initial stages of vestibular symptoms. Inferences from VHIT responses were traditionally low vestibulo-ocular reflex gain or a normal vestibulo-ocular reflex gain. However, the possibility of a third and new variant of the vestibulo-ocular reflex gain has not been clinically explored yet.

OBJECTIVES

To determine and report distinct patterns of vestibulo-ocular reflex gain using VHIT in elderly individuals with vestibular symptoms.

METHODS

Retrospective cross-sectional study was done on a group of elderly patients who were above 70 years of age. These individuals were subjected to VHIT during their symptomatic phase. A vestibulo-ocular reflex gain value between 0.80-01.20 (Horizontal plane) was considered normal. The gain above and below this cutoff range was considered abnormal.

RESULTS

39 elderly patients (15 males and 24 females) whose mean age range was 74.71 years were evaluated for the VHIT response. Vestibulo-ocular reflex gain obtained was categorized into three distinct patterns: (i) normal vestibulo-ocular reflex gain, (ii) reduced vestibulo- ocular reflex gain and (iii) increased vestibulo-ocular reflex gain. The mean vestibulo- ocular reflex gain for both left and right horizontal canals varied significantly between the three groups (p < 0.05). No significant effect of age and vestibulo-ocular reflex gain was noted, though vestibulo-ocular reflex gain was higher in 80 years and above age (p > 0.05).

CONCLUSION

Elderly individuals with dizziness may show varying responses with vestibulo-ocular reflex gain during the symptomatic period. The third type of hyperactive vestibule-ocular reflex responses that emerged from the current study were potential indicators of fluid dynamic changes in the inner ear. These responses need to be explored further as it relates to new clinical markers for both peripheral and central vestibular disorders.

Benefits of pre-labyrinthectomy intratympanic gentamicin: contralateral vestibular responses

OBJECTIVE

To determine the impact of pre-operative intratympanic gentamicin injection on the recovery of patients undergoing translabyrinthine resection of vestibular schwannomas.

METHODS

This prospective, case-control pilot study included eight patients undergoing surgical labyrinthectomy, divided into two groups: four patients who received pre-operative intratympanic gentamicin and four patients who did not. The post-operative six-canal video head impulse test responses and length of in-patient stay were assessed.

RESULTS

The average length of stay was shorter for patients who received intratympanic gentamicin (6.75 days; range, 6-7 days) than for those who did not (9.5 days; range, 8-11 days) (p = 0.0073). Additionally, the gentamicin group had normal post-operative video head impulse test responses in the contralateral ear, while the non-gentamicin group did not.

CONCLUSION

Pre-operative intratympanic gentamicin improves the recovery following vestibular schwannoma resection, eliminating, as per the video head impulse test, the impact of labyrinthectomy on the contralateral labyrinth.

Intratympanic Gentamicin Versus Labyrinthectomy: Inner Ear Sensitivity to Gentamicin and Impact on the Contralateral Labyrinth

Objectives.

To investigate the impact of labyrinthectomy and intratympanic (IT) gentamicin injections on the contralateral labyrinth, we also assessed the response of each individual semicircular canal to each IT gentamicin application.

Methods.

We performed a pilot observational study on tertiary, referral, academic settings. Thirteen patients with unilateral vestibular pathology were organized into two groups, group I (seven patients) receiving IT gentamicin and group II undergoing labyrinthectomy (six patients). All patients underwent six-canal video-head-impulse test in predetermined time intervals. Patients receiving gentamicin were additionally tested 3 to 5 days after every sequential injection, until all ipsilateral canals were ablated, to determine the order of response to gentamicin. We recorded the vestibular-ocular reflex gains and the presence of covert/overt saccades for each canal.

Results.

The posttreatment ipsilateral gains were abnormal. No patient from the gentamicin group developed abnormal contralateral responses, while patients undergoing labyrinthectomy had abnormal contralateral responses from at least one canal, even several months posttreatment. Finally, the lateral semicircular canal was the first one to be affected by IT gentamicin followed by the posterior canal: the superior canal was ablated last.

Conclusion.

In our study, labyrinthectomy had an impact on the responses recorded from the contralateral ear, while IT gentamicin ablated the ipsilateral labyrinthine function without affecting the contralateral responses, possibly because of a milder, more gradual impact. We also show for the first time the order that IT gentamicin application affects the semicircular canals, with the lateral being the first to be affected.

Associations of Video Head Impulse Test and Caloric Testing among Patients with Vestibular Schwannoma

OBJECTIVE

To determine relationships between caloric testing (CT) and video head impulse testing (vHIT) among patients with unilateral vestibular schwannoma (VS). To describe the distribution of CT and vHIT measurements and assess associations with tumor size and self-perceived handicapping effects.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral hospital.

SUBJECTS AND METHODS

Subjects were adults with presumed unilateral VS between 2014 and 2017. Interventions were CT and vHIT. Primary outcomes were vHIT value (abnormal <0.8) and CT value (abnormal >25%). Secondary outcomes were tumor size and Dizziness Handicap Inventory scores.

RESULTS

Fifty-one individuals had complete data for CT and vHIT. The odds of abnormal gain increases by 2.18 for every 10% increase in unilateral weakness on CT (range, 1.44-3.34; P < .001). A significant negative correlation between CT and gain exists (r_s = -0.64, P < .001). Odds of observing saccades increased by 2.68 for every 10% increase in unilateral weakness (range, 1.48-4.85; P = .001). This association was larger in magnitude for overt than covert saccades (odds ratios, 2.48 and 1.59, respectively). Tumor size was significantly associated with an increase in caloric weakness (β = 0.135, P < .001). With every 10-mm increase of tumor size, odds of abnormal gain on vHIT increased 4.13 (range, 1.46-11.66; P = .007). Mean Dizziness Handicap Inventory score was 19.7 (σ = 22), without association to caloric weakness, gain, or tumor size.

CONCLUSION

CT and vHIT both effectively assess vestibular function for patients with VS and correlate to tumor size. These findings are important as vHIT has a lower overall cost, improved patient tolerance, and demonstrated reliability.