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

Comparing Video Head Impulse Testing With Rotary Chair in Pediatric Patients: A Controlled Trial

OBJECTIVES

To investigate the efficacy of video head impulse testing (VHIT) in detecting vestibular loss in pediatric patients with abnormal rotary chair testing, compared to a control group with normal rotary chair testing.

STUDY DESIGN

Prospective, nonrandomized, controlled trial.

SETTING

Pediatric vestibular program at tertiary level children's hospital.

METHODS

Patients 3 to 18 years of age were recruited to undergo VHIT and rotary chair testing between September 2015 and November 2022. VHIT results were compared between an experimental group of 23 patients with vestibular symptoms and abnormal rotary chair testing results versus a control group of 14 patients without vestibular symptoms and with normal rotary chair testing results.

RESULTS

The experimental group demonstrated reduced mean VHIT gain for the lateral semicircular canals (right = 0.83; left = 0.75) relative to the control group (right = 1.04, P = .005; left = 0.98, P < .001), but there was no significant difference between groups in superior and posterior canal responses. Among controls, there were no significant differences in mean gain values for each canal plane between age groups (3-7, 8-12, and 13-18 years) or between genders. A VHIT lateral canal gain value <0.85 and/or corrective saccades demonstrated 100% specificity and 100% positive predictive value for detecting vestibular loss on rotary chair, but only 69.6% sensitivity and 66.7% negative predictive value.

CONCLUSION

VHIT is a useful test for detecting impairment of the lateral semicircular canals in children, though its sensitivity is limited relative to rotary chair. Its role in detecting vertical canal dysfunction in pediatric patients may be more limited and warrants further study.

Mechanisms and Impact of Aminoglycoside-Induced Vestibular Deficits

PURPOSE

Acquired vestibulotoxicity from hospital-prescribed medications such as aminoglycoside antibiotics affects as many as 40,000 people each year in North America. However, there are no current federally approved drugs to prevent or treat the debilitating and permanent loss of vestibular function caused by bactericidal aminoglycoside antibiotics. This review will cover our current understanding of the impact of, and mechanisms underlying, aminoglycoside-induced vestibulotoxicity and highlight the gaps in our knowledge that remain.

CONCLUSIONS

Aminoglycoside-induced vestibular deficits have long-term impacts on patients across the lifespan. Additionally, the prevalence of aminoglycoside-induced vestibulotoxicity appears to be greater than cochleotoxicity. Thus, monitoring for vestibulotoxicity should be independent of auditory monitoring and encompass patients of all ages from young children to older adults before, during, and after aminoglycoside therapy.

Variability in the Results of Vestibular Assessment in Patients with Genetically Confirmed Cerebellar Ataxia, Neuropathy, and Vestibular Areflexia Syndrome

BACKGROUND

Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) presents an unpredictable and uneven clinical development of cerebellar ataxia, neuropathy, and vestibular areflexia. The aim of this study is to report the variability of vestibular test results in genetically confirmed patients with cerebellar ataxia, neuropathy, and vestibular areflexia syndrome.

METHODS

Caloric testing, video head impulse test (vHIT), and rotatory chair testing were performed in 7 patients who presented pathogenic repeat expansions in the replication factor complex unit 1 gene related to cerebellar ataxia, neuropathy, and vestibular areflexia syndrome.

RESULTS

Reduced vestibulo-ocular reflex (VOR) gain was observed in 100% of the patients in rotatory chair testing. Three of them had bilateral areflexia in caloric testing while 2 showed unilateral hypofunction and 2 had no alterations in the test. Only 1 patient had bilateral abnormal vHIT with gains under 0.6 in both ears.

CONCLUSION

Genetic testing allows an early diagnosis of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome, whereby the vestibular system may be affected to different degrees. Rotatory chair testing has a higher sensitivity for the detection of vestibular hypofunction in these patients. Caloric testing can provide additional information. vHIT might underdiagnose patients with mild-to-moderate vestibulopathy.

Stability of Vestibular Testing in Children With Hearing Loss

PURPOSE

The purpose of this study was to evaluate the stability of rotary chair, video head impulse test (vHIT), and vestibular evoked myogenic potential (VEMP) responses in children with normal hearing (NH) and children with cochlear implants (CIs).

METHOD

Retrospective analysis of 66 children (33 males, M _age = 11.4 years, range: 3-18 years) seen in a tertiary clinic and/or research laboratory who completed rotary chair, VEMP, and vHIT across two test sessions between 2012 and 2019. The stability of these measures was compared between two groups: children with NH (n = 35) and children with CI (n = 31). For each outcome, the session difference was calculated by subtracting Session 1 from Session 2.

RESULTS

For rotary chair (gain and phase) and vHIT (gain), linear mixed-effects models revealed that there were no significant interactions or main effects for group (CI vs. NH), time between session, gender, or age on the session difference, suggesting that the outcomes of these measures are stable across sessions. For cervical and ocular VEMP amplitude, there was a significant interaction between group and time between sessions on the session difference. Specifically, children with NH demonstrated larger amplitudes at Session 2, whereas children with CI demonstrated smaller amplitudes at Session 2. Next, test findings were classified as normal, unilaterally abnormal, or bilaterally abnormal for Sessions 1 and 2. Misclassification was defined as a mismatch of classification between sessions. Rotary chair and vHIT had the fewest misclassifications, whereas cervical VEMPs had the most misclassifications in children with CI and ocular VEMPs had the most misclassifications in children with NH. Misclassifications in children with CI were mostly consistent with progressive vestibular loss, whereas misclassifications in children with NH were mostly consistent with improved vestibular function.

CONCLUSIONS

Stability and misclassification rates varied between tests and groups. Overall, rotary chair and vHIT outcomes were stable in both groups; however, VEMPs differentially changed between groups, improving in children with NH and declining in children with CI. Furthermore, despite relative stability, some children with CI evidenced progressive vestibular loss on all measures suggesting that vestibular testing should be completed serially due to the possibility of progression.

Vestibular function in children with cochlear implant: Impact and evaluation

Over the last 30 years, cochlear implant (CI) has been dedicated to improving the rehabilitation of hearing impairments. However, CI has shown potential detrimental effects on vestibular function. For children, due to atypical symptoms and difficulty in cooperating with vestibular function tests, systematic and objective assessments of vestibular function with CI have been conducted sparsely. This review focuses on the impact of vestibular function in children with CI and summarized the evaluation of vestibular function in children. In addition, some recommended strategies are summarized and proposed.

Video head impulse test in bilateral vestibulopathy

Introduction

Bilateral vestibulopathy is a rare chronic condition with multiple etiologies. Bilateral vestibulopathy is characterized mainly by unsteadiness when walking or standing, which worsens in darkness, as well as oscillopsia. The degree of handicap caused by bilateral vestibulopathy is variable and remains controversial.

Objectives

To determine the value of the video Head Impulse Test in quantifying vestibular deficit and to establish its impact on the quality of life.

Methods

Twenty patients (mean age, 41.9 years; range 14–80 years) fulfilling the recent Barany criteria of bilateral vestibulopathy, responded to the Situational Vertigo Questionnaire and underwent vestibular examination including fixation, positional tests, oculomotor test battery and video head impulse test.

Results

The relation between each of the video head impulse test parameters and the scores from the questionnaire were statistically analyzed. We observed that patients with covert saccades on the video head impulse test were more likely to have a better quality of life than those with both covert and overt saccades, regardless of the vestibulo-ocular reflex gain in each semicircular canal. The presence of covert saccades was found to be associated with an improved quality of life regardless of the severity of vestibule ocular reflex-deficit. Our conclusion was that vestibule ocular reflex gain, measured by video head impulse test, does not quantify the severity of affection of quality of life in patients with bilateral vestibulopathy.

Conclusion

Covert saccades are strategies aiming at minimizing the blurring of vision during head movement, that is an adaptive mechanism that improves quality of life. Therefore, we recommend that video head impulse test should be a part of the routine diagnostic workup of bilateral vestibulopathy.

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.

Relationship Between Corrective Saccades and Measures of Physical Function in Unilateral and Bilateral Vestibular Loss

OBJECTIVES

Following the loss of vestibular function, some patients functionally improve and are minimally bothered by their loss of peripheral function while others remain more symptomatic and are unable to return to their activities of daily living. To date, the mechanisms for functional improvement remain poorly understood. The purpose of the present study was to examine the association between corrective saccades and measures of handicap, dynamic visual acuity, gait, and falls.

DESIGN

A retrospective chart review was performed to identify patients who were diagnosed with unilateral or bilateral vestibular hypofunction and who also completed a baseline vestibular rehabilitation evaluation. A total of 82 patients with unilateral vestibular hypofunction and 17 patients with bilateral vestibular hypofunction were identified. The video head impulse test results for each patient were grouped based on the type of presenting saccades. Specifically, the saccade grouping included the following: (1) covert, (2) overt, or (3) a combination of both types of saccades.

RESULTS

The results show that covert saccades are associated with better performance on measures of dynamic visual acuity, gait, and balance in patients with unilateral vestibular hypofunction. Patients exhibiting overt saccades or combination of both covert and overt saccades were more often found to have an abnormal gait speed and be characterized as being at risk for falls using the Dynamic Gait Index. We observed no differences in physical function for those patients with bilateral vestibular hypofunction as a function of saccade grouping.

CONCLUSIONS

When comparing saccade groups (covert, overt, or combination of both), patients with unilateral vestibular hypofunction and covert saccades demonstrated better performance on standard baseline physical therapy measures of dynamic visual acuity and gait and balance. We did not observe any significant associations between saccade group and physical function in patients with bilateral vestibular hypofunction; however, additional studies are needed with adequate sample sizes. Our findings may suggest that corrective saccade latency in patients with unilateral vestibular hypofunction is related to measures of physical function. The extent to which saccade latency has the potential to be a useful target for vestibular rehabilitation is still to be determined and may be promising target to improve functional outcomes.

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.

Evaluation of the vestibulo-ocular reflex in patients with chronic otitis media

Introduction

In recent years, scientific evidence has shown that chronic otitis media may cause balance and vestibular dysfunction.

Objective

To compare the results of the video head impulse test (gain and symmetry of the vestibulo-ocular reflex and presence of covert and overt saccades) in patients with chronic otitis media and controls.

Methods

Cross-sectional study of patients with chronic otitis media (study group), aged between 18 and 60 years. The patients in the study group were further divided according to the chronic otitis media type as (1) non-suppurative, (2) suppurative, and (3) cholesteatomatous. For the comparative analysis, we selected volunteers with no history of ear and vestibular diseases (control group), who met the same inclusion and exclusion criteria as the study group. Patients in both groups underwent a video head impulse test.

Results

The study group consisted of 96 volunteers, and the control group of 61 individuals. The prevalence of vestibular symptoms was 66% in the study group and 3.2% in the control group (p <  0.001). The results show a higher prevalence of changes in the vestibulo-ocular reflex gain (22.9%) and corrective saccades (12.6%) in the chronic otitis media group compared to the control group (p <  0.001). Despite the higher prevalence of changes in gain, the average vestibulo-ocular reflex gains in the chronic otitis media groups were within the pre-defined values ​​of normality; however, the mean vestibulo-ocular reflex gain in the anterior semicircular canal was statistically worse in the cholesteatomatous chronic otitis media group compared to controls (p <  0.001). Regarding the corrective saccades, the prevalence of saccades was statistically higher in the suppurative and cholesteatomatous chronic otitis media subgroups compared to the non-suppurative and control groups (p =  0.004).

Conclusion

The present study demonstrated that chronic otitis media is associated with a higher prevalence of vestibular symptoms and also a higher prevalence of changes in gain and corrective saccades when compared to controls.

Estimating loss of canal function in the video head impulse test (vHIT)

BACKGROUND:

The vestibulo-ocular reflex (VOR) gain is the primary parameter for quantifying and interpreting the video head impulse test (vHIT). Yet, the relationship between the VOR gain and the extent of canal function is not clear.

OBJECTIVE:

The goal of this paper was to determine if the loss of canal function in vHIT can be estimated from the VOR gain.

METHODS:

A model of the VOR was developed that included linear components for the cupula and the velocity storage mechanism as well as nonlinear components for the vestibular nerve and the vestibular nuclei. Multiple simulations were carried out as the level of function for the right and left VOR pathways was varied systematically over their entire range.

RESULTS:

Simulation results were similar to the typical findings in normal individuals as well as in patients with unilateral and bilateral loss of canal function. Based on these simulations, a relationship between the canal function and the VOR gains was established. This relationship was surprisingly independent of most model parameters.

CONCLUSIONS:

The sum of right and left VOR gains (or 2 times the mean of VOR gains) at a given head velocity is an estimate of the total function of the involved canals. This simple formula can estimate the loss of canal function in purely unilateral lesions. For bilateral lesions, the same formula can estimate the total loss of bilateral function but contributions from individual canals cannot be determined without additional information.

Electrocochleography Results in Patients With Bilateral Vestibular Paresis and Sound- or Pressure-Induced Horizontal Nystagmus

OBJECTIVE

To describe the electrocochleography (ECochG) findings in patients with bilateral vestibular paresis and sound- and/or pressure-induced horizontal nystagmus.

DESIGN

Retrospective case series.

SETTING

Tertiary care center.

PATIENTS

Three adult patients with bilateral vestibular paresis and sound- and/or pressure-induced horizontal nystagmus were evaluated from 2012 to 2016.

MAIN OUTCOME MEASURE

All patients underwent ECochG, vestibular evoked myogenic potential (VEMP) testing, bithermal caloric testing, rotary chair testing, audiometric testing, and temporal bone computed tomography (CT). For ECochG, the summating potential (SP) to action potential (AP) ratio was determined.

RESULTS

All patients had normal temporal bone CT, reduced caloric responses bilaterally, decreased gain on rotary chair, and abnormal ECochG. For two subjects, the SP/AP was elevated bilaterally. One subject had unilateral SP/AP elevation. Cervical VEMPs were present in all subjects, but at reduced thresholds in two subjects.

CONCLUSION

SP/AP elevation was found in all three patients with the syndrome of bilateral vestibular paresis and/or sound- or pressure-induced horizontal nystagmus. As the etiology of this syndrome remains unclear, understanding the basis for abnormal ECochG may shed insight into the pathophysiology of this condition.

Evaluating the Diagnostic Accuracy of the Head-Impulse Test: A Scoping Review

Importance

Vestibular symptoms rank among the most common complaints in medicine worldwide. Underlying disorders manifested by these symptoms are generally associated with an impairment of the vestibular-ocular reflex and can be assessed with different diagnostic procedures. In recent years, an increasing number of diagnostic test accuracy studies comparing various head-impulse test (HIT) methods with other diagnostic procedures have been published but not systematically reviewed.

Objective

To conduct a scoping review and describe key characteristics of the growing number of diagnostic studies in patients presenting with vestibular symptoms.

Evidence Review

In April 2017, published studies were identified through searches of 4 bibliographic databases: Medline, Science Citation Index Expanded, the Cochrane Library, and ScienceDirect. Studies were included if they provided diagnostic accuracy data (sensitivity and specificity) for any HIT method with reference to any other vestibular test or clinical diagnosis in patients with vestibular symptoms. Study key characteristics were extracted, and the current literature was described narratively. All analysis took place between June 2017 and July 2018.

Findings

We identified a total of 27 diagnostic studies (including 3821 participants). There were disagreements between diagnostic test accuracy data both within and between studies when different HIT methods were compared with other diagnostic procedures. The proportion of correctly identified people having the disease (sensitivity) ranged between 0% and 100% (median, 41%), whereas the proportion of correctly identified people without the disease (specificity) was higher and ranged between 56% and 100% (median, 94%).

Conclusions and Relevance

Based on the studies included in this review, sensitivity, specificity, and, more importantly, the risk of misdiagnosis and associated undertreatment or overtreatment cannot be reliably estimated by HIT methods for patients with vestibular symptoms. We recommend that further diagnostic studies consider (1) multiple possible underlying causes of vestibular symptoms and multiple test thresholds, (2) a representative sample of patients with and without the disease, and (3) reporting guidelines for diagnostic test accuracy studies.

Rebalancing the Vestibular System by Unidirectional Rotations in Patients With Chronic Vestibular Dysfunction

Introduction: Vestibular dysfunction is a common disorder that results in debilitating symptoms. Even after full compensation, the vestibulo-ocular reflex (VOR) could be further improved by using rehabilitation exercises and visual-vestibular adaptation. We hypothesized that in patients with asymmetric vestibular function, the system could be rebalanced by unidirectional rotations toward the weaker side (i.e., a pure vestibular stimulation).

Methods: Sixteen subjects (5 female and 11 male, 43.2 ± 17.0 years old) with chronic vestibular dysfunction that was non-responsive to other types of medical treatment were recruited for the study (ClinicalTrials.gov Identifier: NCT01080430). Subjects had VOR asymmetry quantified by an abnormal directional preponderance (DP) with rotation test and no previous history of central vestibular problems or fluctuating peripheral vestibular disorders. They participated either in the short-term study (one session) or the long-term study (7 visits over 5 weeks). Rehabilitation consisted of five trapezoid unidirectional rotations (peak velocity of 320°/s) toward the weaker side. Care was taken to slowly stop the rotation in order to avoid stimulation in the opposite direction during deceleration. To study the short-term effect, VOR responses were measured before and 10, 40, and 70 min after a single unidirectional rotational rehabilitation session. For long-term effects, the VOR gain was measured before and 70min after rehabilitation in each session.

Results: We observed a significant decrease in VOR asymmetry even 10 min after one rehabilitation session (short-term study). With consecutive rehabilitation sessions in the long-term study, DP further decreased to reach normal values during the first 2 sessions and only one subjects required further rehabilitation after week 4. This change in DP was due to an increase in responses during rotations toward the weaker side and a decrease in VOR responses during rotations in the other direction.

Conclusion: Our results show that unidirectional rotation can reduce the VOR imbalance and asymmetry in patients with previously compensated vestibular dysfunction and could be used as an effective supervised method for vestibular rehabilitation even in patients with longstanding vestibular dysfunction.

Assessment of vestibular function in elderly patients

PURPOSE OF REVIEW

Individuals over the age of 60 are at an increased risk of falls, even if they do not have an isolated dysfunction of the vestibular system. The aim of this article is to review the various vestibular testing currently available and its usefulness in determining the presence of vestibular dysfunction in the elderly population. The primary vestibular tests to be reviewed include: balance function testing, vestibular evoked myogenic potentials (VEMPs), and video head impulse testing (vHIT).

RECENT FINDINGS

Balance function testing is important as it evaluates the integration of vestibular information along with sensory and visual information, which may also be impaired. VEMP testing provides a small diagnostic yield as most elderly patients have absent or reduced responses. vHIT gain is reduced in this population, but will still be within the normal range for individuals with normal balance function.

SUMMARY

The combination of various vestibular tests provides complimentary information instead of redundant information on the patient's balance function. Each test evaluates various aspects of the vestibular system which are all needed to determine stable balance in the elderly population.

Impact of Target Distance, Target Size, and Visual Acuity on the Video Head Impulse Test

The video head impulse test (vHIT) assesses the vestibulo-ocular reflex. Few have evaluated whether environmental factors or visual acuity influence the vHIT. The purpose of this study was to evaluate the influence of target distance, target size, and visual acuity on vHIT outcomes. Thirty-eight normal controls and 8 subjects with vestibular loss (VL) participated. vHIT was completed at 3 distances and with 3 target sizes. Normal controls were subdivided on the basis of visual acuity. Corrective saccade frequency, corrective saccade amplitude, and gain were tabulated. In the normal control group, there were no significant effects of target size or visual acuity for any vHIT outcome parameters; however, gain increased as target distance decreased. The VL group demonstrated higher corrective saccade frequency and amplitude and lower gain as compared with controls. In conclusion, decreasing target distance increases gain for normal controls but not subjects with VL. Preliminarily, visual acuity does not affect vHIT outcomes.

Bilateral Vestibular Weakness

Bilateral vestibular weakness (BVW) is a rare cause of imbalance. Patients with BVW complain of oscillopsia. In approximately half of the patients with BVW, the cause remains undetermined; in the remainder, the most common etiology by far is gentamicin ototoxicity, followed by much rarer entities such as autoimmune inner ear disease, meningitis, bilateral Ménière’s disease, bilateral vestibular neuritis, and bilateral vestibular schwannomas. While a number of bedside tests may raise the suspicion of BVW, the diagnosis should be confirmed by rotatory chair testing. Treatment of BVW is largely supportive. Medications with the unintended effect of vestibular suppression should be avoided.

The Video Head Impulse Test

In 1988, we introduced impulsive testing of semicircular canal (SCC) function measured with scleral search coils and showed that it could accurately and reliably detect impaired function even of a single lateral canal. Later we showed that it was also possible to test individual vertical canal function in peripheral and also in central vestibular disorders and proposed a physiological mechanism for why this might be so. For the next 20 years, between 1988 and 2008, impulsive testing of individual SCC function could only be accurately done by a few aficionados with the time and money to support scleral search-coil systems—an expensive, complicated and cumbersome, semi-invasive technique that never made the transition from the research lab to the dizzy clinic. Then, in 2009 and 2013, we introduced a video method of testing function of each of the six canals individually. Since 2009, the method has been taken up by most dizzy clinics around the world, with now close to 100 refereed articles in PubMed. In many dizzy clinics around the world, video Head Impulse Testing has supplanted caloric testing as the initial and in some cases the final test of choice in patients with suspected vestibular disorders. Here, we consider seven current, interesting, and controversial aspects of video Head Impulse Testing: (1) introduction to the test; (2) the progress from the head impulse protocol (HIMPs) to the new variant—suppression head impulse protocol (SHIMPs); (3) the physiological basis for head impulse testing; (4) practical aspects and potential pitfalls of video head impulse testing; (5) problems of vestibulo-ocular reflex gain calculations; (6) head impulse testing in central vestibular disorders; and (7) to stay right up-to-date—new clinical disease patterns emerging from video head impulse testing. With thanks and appreciation we dedicate this article to our friend, colleague, and mentor, Dr Bernard Cohen of Mount Sinai Medical School, New York, who since his first article 55 years ago on compensatory eye movements induced by vertical SCC stimulation has become one of the giants of the vestibular world.