Clinical Head Impulse Test Research Articles

Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS): a family with five affected sibs from Turkey

BackgroundCerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS), a relatively common cause of late-onset progressive ataxia, is a genetic disease characterised by biallelic pentanucleotide AAGGG repeat expansion in intron 2 of the replication factor complex subunit 1 gene. Herein, we describe the first molecularly confirmed CANVAS family with five affected siblings from Turkey.Case presentationThe family comprised seven siblings born from healthy non-consanguineous parents. CANVAS phenotype was present in five of them; two were healthy and asymptomatic. Chronic cough was the first symptom reported in all five siblings, followed by the development of sensory symptoms, oscillopsia and imbalance. Clinical head impulse test (HIT) was positive in all cases and video HIT performed on three patients revealed very low vestibulo-ocular reflex gains bilaterally. Magnetic resonance imaging and nerve conduction studies revealed cerebellar atrophy and sensory neuronopathy, respectively. RP-PCR confirmed the homozygous presence of the AAGGG repeat expansion in all five cases.ConclusionGenetic screening for CANVAS should be considered in all patients with late-onset ataxia, sensory disturbances and vestibular involvement, especially in the presence of chronic cough.

Acute Unilateral Peripheral Vestibulopathy After COVID-19 Vaccination: Initial Experience in a Tertiary Neurotology Center.

ObjectiveThe aim of the present study was to identify patients who developed acute unilateral peripheral vestibulopathy (AUPVP) after COVID-19 vaccination.MethodsFor this single-center, retrospective study, we screened the medical records of our tertiary interdisciplinary neurotology center for patients who had presented with AUPVP within 30 days after COVID-19 vaccination (study period: 1 June−31 December 2021). The initial diagnosis of AUPVP was based on a comprehensive bedside neurotological examination. Laboratory vestibular testing (video head impulse test, cervical and ocular vestibular evoked myogenic potentials, dynamic visual acuity, subjective visual vertical, video-oculography, caloric testing) was performed 1–5 months later.ResultsTwenty-six patients were diagnosed with AUPVP within the study period. Of those, n = 8 (31%) had developed acute vestibular symptoms within 30 days after COVID-19 vaccination (mean interval: 11.9 days, SD: 4.8, range: 6–20) and were thus included in the study. The mean age of the patients (two females, six males) was 46 years (SD: 11.7). Seven patients had received the Moderna mRNA vaccine and one the Pfizer/BioNTech mRNA vaccine. All patients displayed a horizontal(-torsional) spontaneous nystagmus toward the unaffected ear and a pathological clinical head impulse test toward the affected ear on initial clinical examination. Receptor-specific laboratory vestibular testing performed 1–5 months later revealed recovery of vestibular function in two patients, and heterogeneous lesion patterns of vestibular endorgans in the remaining six patients.Discussion and ConclusionsThe present study should raise clinicians' awareness for AUPVP after COVID-19 vaccination. The relatively high fraction of such cases among our AUPVP patients may be due to a certain selection bias at a tertiary neurotology center. Patients presenting with acute vestibular symptoms should be questioned about their vaccination status and the date of the last vaccination dose. Furthermore, cases of AUPVP occurring shortly after a COVID-19 vaccination should be reported to the health authorities to help determining a possible causal relationship.

Is the clinical head impulse test helpful in cochlear implantation candidacy evaluation?

Vestibular dysfunction is a known risk of cochlear implantation (CI). However, the utility of the physical exam to screen CI candidates for vestibular dysfunction is not well-studied. The objective of this study is to evaluate the preoperative role of the clinical head impulse test (cHIT) in subjects undergoing CI surgery evaluation. We conducted a retrospective review of 64 adult CI candidacy cases between 2017 and 2020 at a tertiary health care center. All patients underwent audiometric testing and evaluation by the senior author. Patients with an abnormal catch-up saccade contralateral to their worse hearing ear during cHIT were referred for formal vestibular testing. Outcomes included clinical and formal vestibular results, operated ear with regard to audiometric and vestibular results, and postoperative vertigo. Among all CI candidates, 44% (n = 28) reported preoperative disequilibrium symptoms. Overall, 62% (n = 40) of the cHITs were normal, 33% (n = 21) were abnormal, and 5% (n = 3) were inconclusive. There was one patient who presented with a false positive cHIT. Among the patients who endorsed disequilibrium, 43% had a positive preoperative cHIT. Fourteen percent of the subjects (n = 9) without disequilibrium had an abnormal cHIT. In this cohort, bilateral vestibular impairment (71%) was more common than unilateral vestibular impairment (29%). In 3% of the cases (n = 2), surgical management was revisited or altered due to cHIT findings. There is a high prevalence of vestibular hypofunction in the CI candidate population. Self-reported assessments of vestibular function are often not congruent with cHIT results. Clinicians should consider incorporating cHITs as part of the preoperative physical exam to potentially avoid bilateral vestibular dysfunction in a minority of patients.

A Simple Gain-Based Evaluation of the Video Head Impulse Test Reliably Detects Normal Vestibulo-Ocular Reflex Indicative of Stroke in Patients With Acute Vestibular Syndrome

Objective: The head impulse test (HIT) assesses the vestibulo-ocular reflex (VOR) and is used to differentiate vestibular neuritis (abnormal VOR) from stroke (normal VOR) in patients presenting with an acute vestibular syndrome (AVS). The video-oculography-based HIT (vHIT) quantifies VOR function and provides information imperceptible for the clinician during clinical bedside HIT. However, the vHIT—like an electrocardiogram—requires experienced interpretation, which is especially difficult in the emergency setting. This calls for a simple, reliable and rater-independent way of analysis.Methods: We retrospectively collected 171 vHITs performed in patients presenting with AVS to our emergency department. Three neuro-otological experts comprehensively assessed the vHITs including interpretability (artifacts), VOR gain (eye/head velocity ratio), velocity profile (abrupt decline) and corrective saccades (overt/covert). Their consensus rating (abnormal/peripheral vs. normal/central) was compared to a simple algorithm that automatically classified the vHITs based on a single VOR gain cutoff (0.7).Results: Inter-rater agreement between experts was high (Fleiss' kappa = 0.74). Five (2.9 %) vHITs were “uninterpretable” according to experts' consensus, 80 (46.8 %) were rated “normal” and 86 (50.3 %) “abnormal”. The algorithm had substantial agreement with the experts' consensus (Cohen's kappa = 0.75). Importantly, it correctly classified all of the normal/central vHITs denoted by the experts (100% specificity) and at the same time it had sufficient sensitivity (75.6%) in detecting abnormal/peripheral vHITs.Conclusion: A simple, automated, gain-based evaluation of the vHIT reliably detects normal/central VOR and may be a feasible and effective tool to screen AVS patients for potentially underlying stroke in the emergency setting.

Prevalence of Vestibular Disorders in Independent People Over 50 That Experience Dizziness.

People aged over 50 are the most likely to present to a physician for dizziness. It is important to identify the main cause of dizziness in order to develop the best treatment approach. Our goal was to determine the prevalence of benign paroxysmal positional vertigo (BPPV), and peripheral and central vestibular function in people that had experienced dizziness within the past year aged over 50. One hundred and ninety three community-dwelling participants aged 51–92 (68 ± 8.7 years; 117 females) were tested using the clinical and video head impulse test (cHIT and vHIT) to test high-frequency vestibular organ function; the head thrust dynamic visual acuity (htDVA) test to test high-frequency visual-stability; the dizziness handicap inventory (DHI) to measure the impact of dizziness; as well as sinusoidal and unidirectional rotational chair testing to test low- to mid-frequency peripheral and central vestibular function. From these assessments we computed the following measures: HIT gain; htDVA score; DHI score; sinusoidal (whole-body; 0.1–2 Hz with 30°/s peak-velocity) vestibulo-ocular reflex (VOR) gain and phase; transient (whole-body, 150°/s2 acceleration to 50°/s constant velocity) VOR gain and time constant; optokinetic nystagmus (OKN) gain and time constant (whole-body, 50°/s constant velocity rotation). Our study showed that BPPV, and peripheral or central vestibular hypofunction were present in 34% of participants, suggesting a vestibular cause to their dizziness. Over half (57%) of these with a likely vestibular cause had BPPV, which is more than twice the percentage reported in other dizzy clinic studies. Our findings suggest that the physical DHI score and VOR time constant were best at detecting those with non-BPPV vestibular loss, but should always be used in conjunction with cHIT or vHIT, and that the htDVA score and vHIT gain were best at detecting differences between ipsilesional and contralesional sides.

Determination of the Test Retests Reliability of the Otometrics Video Head Impulse Test (Vhit) Among Healthy Adults

Video head impulse test (vHIT) is a clinical head impulse test to evaluate the vestbulo ocular re?ex (VOR). The VOR is the re?ex mechanism that carries out the functon of gaze stabilizaton which is one of the most important functons of the balance system. Material and Methods: Main aim of this study to determine the test retest reliability of the otometrics video head impulse test (vHIT) among healthy adults aged 18 to 35 years (mean age of 22.51 years). A repeated measures study that recruited 51 young adults (102 ears, 33% were males and 67% were females). All subjects flled Malay Version Vertgo Symptom Scale (MVVSS) as a screening then vHIT testng done for the frst and second session within 1 to 2 weeks. The vHIT was carried out according to the standard protocol and the head of the partcipants were rotated in the di?erent planes which was lateral, anterior and posterior. Results: The lateral canals have high gain compared to anterior and posterior canals in session 1 and session 2. Then, there is no signifcance di?erence (p>0.05 between VOR gain of session 1 and session 2 for each semicircular canals except for the lef lateral. The right lateral showed the highest correlaton ~ 0.746 while right anterior showed the lowest correlaton ~ 0.545. However, the overall canals revealed moderate to high correlaton (0.5 to 0.7). Conclusion: vHIT is a good test to determine the vestbular functon by measuring the VOR gain of each canal.

Computing Endolymph Hydrodynamics During Head Impulse Test on Normal and Hydropic Vestibular Labyrinth Models.

Hypothesis: Build a biologic geometry based computational model to test the hypothesis that, in some circumstances, endolymphatic hydrops can mechanically cause enhanced eye velocity responses during clinical conditions of the head impulse test.Background: Some recent clinical and experimental findings had suggested that enhanced eye velocity responses measured with the video head impulse test could not only be caused by recording artifacts or central disfunction but also could be directly caused by the mechanical effect of endolymphatic hydrops on horizontal semicircular canal receptor.Methods: Data from clinical video head impulse test was computed in three biologic-based geometry models governed by Navier-Stokes equations; six head impulses of incrementally increasing peak head velocity were computed in each one of the three different geometric models, depending on absence, canal or utricular hydrops.Results: For all computed head impulses an increased endolymphatic pressure was measured at the ampullar region of the horizontal semicircular canal on both canal and utricular hydrops models. The mean of aVOR gain was 1.01 ± 0.008 for the no-hydrops model, 1.14 ± 0.010 for the canal hydrops model was, and 1.10 ± 0.007 for the utricular hydrops model.Conclusion: The results of the physical computation models support-the hypothesis that in endolymphatic hydrops conditions, which are affecting horizontal semicircular canal and utricular region on moderate dilatations, the eye velocity responses output-by the aVOR will be enhanced by a 1.14 factor and aVOR gain values will be enhanced by over 1.1 for impulses to the right side.

Vestibular function in severe GH deficiency due to an inactivating mutation in the GH-releasing hormone receptor gene.

Body balance involves the vestibular, visual, and proprioceptive systems. IGF-I is a GH-dependent key factor in the development and postnatal differentiation of the inner ear in mice and men, but its role in the vestibular function in adult humans is unknown. We have previously described a cohort of individuals with severe isolated GH deficiency (IGHD) caused by a mutation in the GHRH receptor (GHRHR) gene. These individuals complain of dizziness, exhibit mild sensorineural loss, but have normal postural balance, without increase in falls risk. The aim of this study was to evaluate their vestibular function. We performed physical examination (clinical head impulse and Fukuda dynamic stepping test), oculomotor (saccadic eye movements, spontaneous, semi-spontaneous and opotokinetic nystagmus, and pendular tracking) and caloric stimulation (postcaloric reflex and ocular fixation index) tests, in 15 GH-naïve IGHD (seven males) and 15 controls (five males). IGHD subjects showed lower height and weight, with similar BMI to controls, and higher number of individuals with abnormal clinical head impulse test and abnormal oculomotor tests, namely the saccadic movements and the spontaneous nystagmus. There was a nonsignificant trend in abnormalities in the Fukuda stepping test and postcaloric reflex test. Adult untreated IGHD individuals have higher prevalence of moderate peripheral vestibular impairment, and of abnormal vestibular-ocular reflex.

Rehabilitation of dynamic visual acuity in patients with unilateral vestibular hypofunction: earlier is better.

Patients with acute peripheral unilateral hypofunction (UVH) complain of vertigo and dizziness and show posture imbalance and gaze instability. Vestibular rehabilitation therapy (VR) enhances the functional recovery and it has been shown that gaze stabilization exercises improved the dynamic visual acuity (DVA). Whether the effects of VR depend or not on the moment when it is applied remains however unknown, and investigation on how the recovery mechanisms could depend or not on the timing of VR has not yet been tested. Our study investigated the recovery of DVA in 28 UVH patients whose unilateral deficit was attested by clinical history and video head impulse test (vHIT). Patients were tested under passive conditions before (pre-tests) and after (post-tests) being subjected to an active DVA rehabilitation protocol. The DVA protocol consisted in active gaze stabilization exercises with two training sessions per week, each lasting 30 min, during four weeks. Patients were sub-divided into three groups depending on the time delay between onset of acute UVH and beginning of VR. The early DVA group (N = 10) was composed of patients receiving the DVA protocol during the first 2 weeks after onset (mean = 8.9 days), the late group 1 (N = 9) between the 3rd and the 4th week (mean = 27.5 days after) and the late group 2 (N = 9) after the 1st month (mean: 82.5 days). We evaluated the DVA score, the angular aVOR gain, the directional preponderance and the percentage of compensatory saccades during the HIT, and the subjective perception of dizziness with the Dizziness Handicap Inventory (DHI). The pre- and post-VR tests were performed with passive head rotations done by the physiotherapist in the plane of the horizontal and vertical canals. The results showed that patients submitted to an early DVA rehab improved significantly their DVA score by increasing their passive aVOR gain and decreasing the percentage of compensatory saccades, while the late 1 and late 2 DVA groups 1 and 2 showed less DVA improvement and an inverse pattern, with no change in the aVOR gain and an increase in the percentage of compensatory saccades. All groups of patients exhibited significant reductions of the DHI score, with higher improvement in subjective perception of dizziness handicap in the patients receiving the DVA rehab protocol in the first month. Our data provide the first demonstration in UVH patients that earlier is better to improve DVA and passive aVOR gain. Gaze stabilization exercises would benefit from the plastic events occurring in brain structures during a sensitive period or opportunity time window to elaborate optimal functional reorganizations. This result is potentially very important for the VR programs to restore the aVOR gain instead of recruiting compensatory saccades assisting gaze stability.

Reader response: Teaching Video NeuroImages: Vestibulo-ocular reflex defect in cerebellar stroke.

We read with interest the Teaching Video NeuroImage article by Witsch et al.1 The authors stated that abnormal vestibulo-ocular reflex, which cannot be measured by the naked eye, is indirectly implied by way of observing a corrective catch-up saccade. Our group demonstrated with quantitative head impulse test that catch-up saccade can be generated in acute cerebellar stroke, even when the gain of the vestibulo-ocular reflex is not abnormal.2 We suggest, with the widespread availability of portable video head impulse test,3 that abnormal clinical head impulse test should be rapidly confirmed at point of care by measuring both the vestibulo-ocular reflex gain and catch-up saccade parameters.

The Video Head Impulse Test: Our Experience in 45 Cases.

To evaluate the role of video head impulse test in the diagnosis of peripheral vestibular disorders, we performed an observational study in the outpatient department in a tertiary setup in which the clinical head impulse test and the video head impulse test were performed on 45 patients with clinically suspected peripheral vestibular disorders, and their results were correlated. To analyse our results, each ear was counted individually and hence, among 45 patients, 12 out of 90 ears showed abnormal clinical head impulse test for lateral semicircular canals and 27 out of 90 ears showed abnormal video head impulse test for lateral semicircular canals. This gave us an additional diagnostic accuracy of 21.1% on using video head impulse test for the lateral semicircular canals as compared to the clinical head impulse test. Video head impulse test is a physiological, quick and well tolerated test for assessing the vestibular function, and the only practical test for assessing the vertical semicircular canal function. Video head impulse test provides valuable information in localising the site of lesion as it assesses the semicircular canals individually. Video head impulse is merely not an objectification and registration system for the clinical head impulse test as it provides additional information such as vestibulo-ocular reflex gain, and occurrence of covert refixation saccades which cannot be picked up by naked eyes.

Increased intracranial tension and cochleovestibular symptoms: an observational clinical study

ObjectivesMeniere’s disease is thought to be pathophysiologically due to increased pressure in the endolymphatic spaces leading to distortion of the sensory elements. As the inner ear fluids are in direct and indirect contact with cerebrospinal fluid (CSF), it was hypothesized that changes in CSF hydrodynamics could affect inner ear fluid pressures.Patients and MethodsThis study was conducted on 150 patients presenting with benign increased intracranial tension diagnosed by Dandy’s criteria and by radiological data. All patients were subjected to a detailed vertigo questionnaire and underwent comprehensive clinical, audiological, and vestibular testing to detect any vestibular abnormalities.ResultsOf the studied patients, 38 (25.3%) (34 females and four males) presented with audiovestibular symptoms: ear fullness and/or hearing loss, tinnitus, attacks of vertigo, and instability. Some patients reported atypical positional or motion-induced vertigo. A total of 13 patients presented with sensorineural hearing loss (SNHL). Clinical head impulse test (HIT) was positive in 30 patients, abnormal caloric test results in 24 patients, and 12 had positive Dix–Hallpike test results. All patients with audiovestibular symptoms were previously treated with betahistine (24 mg, three times a day) with poor response. Patients with abnormal test results were shifted to acetazolamide+betahistine. Thirty patients had a dramatic response on both audiological and vestibular manifestations.ConclusionChanges in CSF pressure significantly affect inner ear fluids in some patients. Symptoms and tests may mimic Meniere’s disease, and we recommend evaluating patients with atypical Meniere’s disease (MD), especially early bilateral affection and/or poor response to conventional therapy, for increased intracranial tension (ICT). Further testing of other cochlea-vestibular functions in these patients is under way.

Recent advances in head impulse test findings in central vestibular disorders.

The head impulse test (HIT) is used to evaluate the vestibulo-ocular reflex (VOR) during a high-velocity head rotation. Corrective catch-up saccades that occur during or after the HITs usually indicate peripheral vestibular hypofunction, whereas in acute vestibular syndrome, normal clinical (bedside) HITs should prompt a search for a central lesion. However, recent quantitative studies that evaluated HITs using magnetic search coils or video-based techniques have demonstrated that specific patterns of HIT abnormalities are associated with central vestibular disorders. While normal clinical HITs are typical of central lesions, discrepancies have been observed between clinical and quantitative HITs. The horizontal head impulse VOR gains can be significantly reduced unilaterally or bilaterally (positive HITs) in lesions involving the vestibular nucleus, nucleus prepositus hypoglossi, or flocculus. In diffuse cerebellar lesions, the VOR gain during horizontal head impulses may increase (hyperactive) with corrective saccades directed the opposite way. The presence of cross-coupled vertical corrective saccades during horizontal HITs is also suggestive of diffuse cerebellar lesions. Lesions involving the vestibular nucleus, medial longitudinal fasciculus, and cerebellum may show decreased or increased gains of the VOR during vertical HITs. Defining the differences in patterns observed during abnormal HITs may help practitioners localize the responsible lesions in both central and peripheral vestibulopathy.

Editors' note: Clinical Reasoning: Labyrinthine hemorrhage: An unusual etiology for peripheral vertigo

“Clinical Reasoning: Labyrinthine hemorrhage: An unusual etiology for peripheral vertigo” discussed the case of a man with worsening vertigo caused by a spontaneous labyrinthine hemorrhage. Dr. Chen comments that while the head impulse test remains the most important clinical test to differentiate peripheral from central causes of vertigo, it is a subjective test. He argues for the use of video head impulse test (vHIT), a system for testing the vestibulo-ocular reflex of each semicircular canal at high frequency, which is more sensitive than the clinical head impulse test. Drs. Parikh and Frank, authors of the article, agree with Dr. Chen but add that caloric testing is more sensitive than vHIT in patients with Meniere disease and in patients with only moderate vestibular dysfunction. They explain that while clinicians should continue to consider incorporating technology such as vHIT as additional neurologic tools, the clinical history and examination remain the cornerstone of neurology; therefore, the head impulse test should remain the starting point. “Clinical Reasoning: Labyrinthine hemorrhage: An unusual etiology for peripheral vertigo” discussed the case of a man with worsening vertigo caused by a spontaneous labyrinthine hemorrhage. Dr. Chen comments that while the head impulse test remains the most important clinical test to differentiate peripheral from central causes of vertigo, it is a subjective test.

Reader response: Clinical Reasoning: Labyrinthine hemorrhage: An unusual etiology for peripheral vertigo.

I read with interest the Resident & Fellow Clinical Reasoning by Drs. Parikh and Frank.1 In differentiating peripheral (e.g., acute unilateral vestibular loss) from central causes of vertigo (e.g., acute posterior circulation stroke), the clinical head impulse test remains the most important clinical test. However, as a clinical test, it is subjective and, depending on examiner experience, its interpretation is variable. With the widespread availability of the video head impulse test, which provides quantitative information on the vestibulo-ocular reflex and catch-up saccade, the head impulse sign can be rapidly confirmed at point of care. This should now be considered part of the initial workup.

Clinical and video head impulse test in the diagnosis of posterior circulation stroke presenting as acute vestibular syndrome inthe emergency department.

Head impulse test (HIT) is the critical bedside examination which differentiates vestibular neuritis (VN) from posterior circulation stroke (PCS) in acute vestibular syndrome (AVS). Video-oculography based HIT (vHIT) may have aadditional strength in making the differentiation. Patients admitted to the emergency department of a tertiary-care medical center with AVS were studied. An emergency specialist and a neurologist performed HIT. vHIT was conducted by an neuro-otology research fellow. Forty patients 26 male, 14 female with a mean age of 49 years were included in the analyses. Final diagnoses were VN in 24 and PCS in 16 patients.In the VN group, clinical HIT was assessed as abnormal in 19(80%) cases by the emergency specialist and in 20(83%) by the neurologist. In all PCS patients, HIT was recorded as normal both by the emergency specialist and the neurologist (100%).On vHIT, patients with VN had significantly low gain values for both the ipsilesional and contralesional sides when compared with the healthy controls, with significantly lower figures for the ipsilesional side (p < 0.001). All patients in this group had normal DWI-MRI.PCS patients had bilaterally low gain (p < 0.05) on vHIT. However, gain asymmetry was not significant. Subgroup analyses according to presence of brainstem involvement revealed bilateral low gain (p < 0.05) in patients with brainstem infarction (anterior inferior cerebellar artery-posterior inferior cerebellar artery stroke, AICA-PICA stroke) whereas patients with pure cerebellar infarction (posterior inferior cerebellar artery-superior cerebellar artery stroke, PICA-SCA stroke) had gain values similar to healthy controls.With a gain cut-off ≤0.75 and gain asymmetry cut-off ≥17%, as determined by ROC analysis, 100% of PCS patients and 80% of VN patients were correctly diagnosed. Clinical HIT, either performed by an emergency specialist or neurologist is equivalent to vHIT gain and gain asymmetry analysis as conducted by neuro-otologist in the diagnosis of PCS, albeit mislabeling about 20% of VN patients. vHIT does not appear to yield additional diagnostic information. These findings indicate the strength of clinical HIT. Pure gain-based vHIT analysis seems limited and needs to be incorporated with saccade analysis.

Video head impulse test: a review of the literature.

Video head impulse test (vHIT) is a new testing which able to identify the overt and covert saccades and study the gain of vestibulo-ocular reflex (VOR) of each semicircular canal. The aim of this study is to review the clinical use of vHIT in patients with vestibular disorders in different diseases. PubMed and Cochrane databases were searched for all articles that defined vHIT, compared vHIT with another clinical test, and studied the efficacy of vHIT as diagnostic tools with vestibular disease. 37 articles about vHIT were reviewed. All articles studied the vHIT in English and French languages up to May 2015 were included in the review. Editorial articles or short comments, conference abstracts, animal studies, and language restriction were excluded from the review. Four systems were used in the literature to do the vHIT. vHIT is physiological quick test, which studied the VOR at high frequency of each semicircular canal by calculating the duration ratio between the head impulse and gaze deviation. vHIT is more sensitive than clinical head impulse test (cHIT), especially in patient with isolated covert saccades. vHIT test is diagnostic of vestibular weakness by gain reduction and the appearance of overt and covert saccades. If the vHIT is normal, then caloric test is mandatory to rule out a peripheral origin of vertigo. It is recommended to test each semicircular canal, as isolated vertical canal weakness was identified in the literature. More investigation would be required to determine the evolution of the VOR gain with the progression of the vestibular disease.

Video head impulse test in peripheral vestibular diseases

The function of the semicircular canal receptors and the pathway of the vestibulo-ocular reflex (VOR) can be diagnosed with the clinical head impulse test. The aim of the study was to investigate the horizontal VOR by means of video head impulse test in peripheral vestibular disorders. Using the vHIT, we examined horizontal semicircular canal VOR in a group of 55 patients and a control group of 20 healthy subjects. The group of patients included 10 cases of vestibular neuritis (VN), 6 cases of vestibular schwannoma (VS), 12 cases of Meniere's disease (MD), and 15 cases of bilateral vestibulopathy (BV), as well as 13 cases of idiopathic sudden hearing loss with vertigo (ISHL). Instantaneous gains of 40 ms, 60 ms and 80 ms of horizontal VOR were 0.88 ± 0.17, 0.94 ± 0.13 and 0.96 ± 0.13, respectively. Regression gain at 60 ms was 0.99 ± 0.11, and asymmetry was 5.6 ± 3.5. Normal range of 60 ms instantaneous gain was > 0.73, normal range of regression gain was > 0.80. Abnormal vHIT was found in VS (100%), VN (90.9%), BV (86.7%), MD (40.0%) and ISHL (38.5%). Three conditions of refixation saccades occurred in cases with abnormal VOR: isolated covert saccades (12.5%), isolated overt saccades (45.0%) and the combination of overt and covert saccades (42.5%). The vHIT detects abnormal VOR changes in the combination of gain assessment and refixation saccades. Since isolated covert saccades in VOR changes can only be seen with vHIT, peripheral vestibular disorders are likely to be misdiagnosed with the HIT.

Covert anti-compensatory quick eye movements during head impulses.

BackgroundCatch-up saccades during passive head movements, which compensate for a deficient vestibulo-ocular reflex (VOR), are a well-known phenomenon. These quick eye movements are directed toward the target in the opposite direction of the head movement. Recently, quick eye movements in the direction of the head movement (covert anti-compensatory quick eye movements, CAQEM) were observed in older individuals. Here, we characterize these quick eye movements, their pathophysiology, and clinical relevance during head impulse testing (HIT).MethodsVideo head impulse test data from 266 patients of a tertiary vertigo center were retrospectively analyzed. Forty-three of these patients had been diagnosed with vestibular migraine, and 35 with Menière’s disease.ResultsCAQEM occurred in 38% of the patients. The mean CAQEM occurrence rate (per HIT trial) was 11±10% (mean±SD). Latency was 83±30 ms. CAQEM followed the saccade main sequence characteristics and were compensated by catch-up saccades in the opposite direction. Compensatory saccades did not lead to more false pathological clinical head impulse test assessments (specificity with CAQEM: 87%, and without: 85%). CAQEM on one side were associated with a lower VOR gain on the contralateral side (p<0.004) and helped distinguish Menière’s disease from vestibular migraine (p = 0.01).ConclusionCAQEM are a common phenomenon, most likely caused by a saccadic/quick phase mechanism due to gain asymmetries. They could help differentiate two of the most common causes of recurrent vertigo: vestibular migraine and Menière’s disease.

Detection of isolated covert saccades with the video head impulse test in peripheral vestibular disorders

The function of the semicircular canal receptors and the pathway of the vestibulo-ocular-reflex (VOR) can be diagnosed with the clinical head impulse test (cHIT). Recently, the video head impulse test (vHIT) has been introduced but so far there is little clinical experience with the vHIT in patients with peripheral vestibular disorders. The aim of the study was to investigate the horizontal VOR (hVOR) by means of vHIT in peripheral vestibular disorders. Using the vHIT, we examined the hVOR in a group of 117 patients and a control group of 20 healthy subjects. The group of patients included vestibular neuritis (VN) (n=52), vestibular schwannoma (VS) (n=31), Ménière's disease (MD) (n=22) and bilateral vestibulopathy (BV) (n=12). Normal hVOR gain was at 0.96 ± 0.08, while abnormal hVOR gain was at 0.44 ± 0.20 (79.1% of all cases). An abnormal vHIT was found in VN (94.2%), VS (61.3%), MD (54.5%) and BV (91.7%). Three conditions of refixation saccades occurred frequently in cases with abnormal hVOR: isolated covert saccades (13.7%), isolated overt saccades (34.3%) and the combination of overt and covert saccades (52.0%). The vHIT detects abnormal hVOR changes in the combination of gain assessment and refixation saccades. Since isolated covert saccades in hVOR changes can only be seen with vHIT, peripheral vestibular disorders are likely to be diagnosed incorrectly with the cHIT to a certain amount.