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To evaluate pre- and post-operative semicircular canal function in patients with vestibular schwannoma (VS) by the video Head Impulse Test (vHIT). Nineteen patients with VS who underwent surgery were enrolled in this study. The gain in vestibulo-ocular reflex (VOR) and the degree of scatter in catch-up saccades were examined pre- and post-operatively for the semicircular canals in VS patients. Ten of 19 cases (52.6 %) with VS were defined as demonstrating both superior vestibular nerve (SVN) and inferior vestibular nerve (IVN) impairment from the results of pre-operative vHIT. Hearing level and subjective vestibular symptoms showed significant correlations with pre-operative semicircular canal function. Compared to pre-operative vHIT results, VOR gains within 1 month after surgery were significantly reduced in all three canals; however, significant differences had disappeared in the anterior and posterior semicircular canals at 6 months after surgery. Cases of unknown origin had a significantly greater reduction in posterior semicircular canal function after surgery compared with those with disease of IVN origin. As vHIT could evaluate pre-operative vestibular nerve impairment, post-operative VOR gain reduction and the degree of vestibular compensation, semicircular canal function evaluated by vHIT provides a good deal of useful information regarding VS patients undergoing surgery compared to caloric testing, and vHIT should be performed pre- and post-operatively for patients with VS. [ABSTRACT FROM AUTHOR]

Purpose: When a dizzy patient with episodic vertigo has an abnormal caloric and a normal video head impulse test (vHIT), this caloric–vHIT dissociation provides vital information for a diagnosis of Ménière's disease (MD). Endolymphatic hydrops (EH), a histological marker of MD, is hypothesized to be involved in the caloric–vHIT dissociation in MD through hydropic duct distension of the horizontal semicircular canal (SC). This study was designed to determine the impact of EH on the function of horizontal SC during caloric stimulation. Methods: Caloric test and vHIT were used to evaluate the function of horizontal SC every six months, annual magnetic resonance imaging (MRI) was used to evaluate the degree of EH size in the vestibule, and monthly vertigo and hearing evaluation was done for 12 months. EH shrinkage was defined as the size change of vestibular EH from significant to none. Results: Among 133 MD patients evaluated for eligibility, 67 patients with caloric–vHIT dissociation entered the study. Fifteen participants had EH shrinkage (G-I), while 52 participants had no remarkable EH change (G-II). Average values (IQR) of the maximum slow phase velocity in G-I and G-II were 29.6 (13.0–34.0) and 25.9 (17.3–31.3), respectively, at baseline, 26.1 (9.0–38.0) and 23.6 (18.0–28.3) at 12 months. Two-factor repeated-measures ANOVA showed no significant differences between the groups (P = 0.486). The values of vestibulo-ocular reflex gain of the horizontal SC in G-I and G-II remained above 0.8 during the study period. Conclusions: EH detected by MRI shows limited correlation with caloric stimulation results. [ABSTRACT FROM AUTHOR]

Sudden sensorineural hearing loss with vertigo (SHLV) and vestibular neuritis (VN) can result in prolonged dizziness. This study aimed to compare the video head impulse test (vHIT) of patients with SHLV and VN. Fifteen patients with SHLV and 21 patients with VN who visited the Vertigo/Dizziness Center of our hospital between December 2016 and February 2023 were included. vHIT was performed at the time of admission, and the VOR gain and catch up saccade (CUS) in the three types of semicircular canals (SCCs) were analyzed. Pathologic vHIT results were observed most frequently in the posterior SCC (73%), followed by lateral (53%) and anterior (13%) SCCs in the SHLV group. In contrast, pathologic vHIT results were observed most frequently in the lateral SCC (100%), followed by the anterior (43%) and posterior SCC (24%) SCCs in the VN group. Pathological vHIT results in the lateral and posterior SCC showed significant differences between the two groups, but for anterior SCC, no significant differences were found. Comparison of the two vHIT results revealed differences in the SCC dysfunction patterns. This may be due to the different pathophysiological mechanisms of the two vestibular disorders, which may result in prolonged vertigo. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: Current clinical practice considers the vestibulo-ocular reflex (VOR) gain as registered by the video head impulse test (vHIT) as the primary measure for semicircular canal function, while the role of the re-fixation saccades (RSs) is still under evaluation. The goal of the study was to appraise the added benefit of RS towards the improvement of vHIT diagnostic accuracy in cases of suspected left horizontal semicircular canal dysfunction. Methods: The vHIT recordings of 40 patients with left-sided horizontal VOR gains <0.8 were retrospectively evaluated for the presence of RS. The study groups included 20 patients with a final diagnosis of left horizontal semicircular canal dysfunction and 20 patients for whom vestibular dysfunction was ruled out. Results: Gain values >0.72 were found in all patients with no vestibular disease and in 4 (20%) patients having vestibulopathy. Significantly higher average left-sided RS velocity and frequency were found among the vestibular patients. VOR gain <0.72 was found to be highly specific for the diagnosis of vestibular dysfunction. However, for gain values in the range of 0.72–0.79, the presence of RS with frequency >80% largely improved vHIT diagnostic accuracy. Conclusions: Although VOR gain <0.8 is considered to reflect dysfunction, a significant false-positive rate for left-sided horizontal vHIT was found for gains in the range of 0.72–0.79. The presence of RS with frequency >80% could improve vHIT diagnostic ability in these patients. [ABSTRACT FROM AUTHOR]

Caloric irrigation (CI) is the gold standard to investigate peripheral vestibular dysfunction. The video head impulse test (vHIT) is faster and more accessible and may be useful during acute vertigo stroke risk differentiation. Comparative studies between the two methods are needed. The objective of this study was to compare vestibular function data derived from caloric irrigation with that from vHIT. This study included 80 patients with acute onset vertigo who underwent caloric irrigation and vHIT. CI derived sum of slow phase velocities (SPVs) and unilateral weakness (UW) were compared with vHIT vestibulo-ocular reflex (VOR) gain and gain asymmetry (GA) using correlation analyses. Optimal cut offs for vHIT VOR gain and GA were calculated using Youden indexes. There was a strong positive correlation between the asymmetry measures UW and GA whereas the correlation between the sum of SPVs and VOR gain was weaker. The optimal cut offs to diagnose unilateral vestibular weakness were 0.80 for VOR gain and 28% for GA; with specificities for predicting normal caloric irrigation results of 55% and 93%, respectively. In one third of cases the results from caloric irrigation and vHIT dissociated. The results from vHIT correlated with those from CI, still neither test seem to have the accuracy to replace the other. GA appears as an attractive measure in acute vertigo as the high specificity can be used to identify those with a substantial probability of normal vestibular function in need of more comprehensive work-up for central causes. To diagnose vestibular dysfunction, CI remains gold standard. [ABSTRACT FROM AUTHOR]

Objectives  The aim of this article was to evaluate the relationship between signal intensity of the labyrinth and vestibulocochlear function and morphologic features of vestibular schwannoma (VS). Design  Cross-sectional Study. Setting  Tertiary referral center. Participants  Fifty-four patients with sporadic, untreated VS. Main Outcome Measure  Signal intensity of the cochlea and vestibule (SIRc and SIRv: signal intensity of cochlea/vestibule compared with cerebellar signal intensity; AURc and AURv: SIRc/SIRv of the affected side compared with the unaffected side) in 1.5T T2-weighted images was correlated with size (Hannover classification), cystic status, distance from the fundus of the internal auditory canal, video head impulse test (vHIT), and audiometry. Results  Signal intensity of the vestibule was higher than that of the cochlea (p  < 0.01). Large tumors had lower SIRc than smaller tumors (p  = 0.03); Hannover T1 tumors had higher SIRc (p  < 0.01), SIRv (p  < 0.01), AURc (p  < 0.01) and AURv (p  < 0.01) than the rest; heterogenous and cystic tumors had higher SIRv than solid large tumors (p  = 0.02); superior vestibular nerve pattern on vHIT had higher SIRv and AURv than inferior vestibular nerve and mixed patterns (p  = 0.03 and 0.004, respectively); and there was a weak correlation between AURv and speech discrimination (r  = 0.33, p  = 0.04). Conclusion  A more abnormal signal intensity of the labyrinth is associated with larger size and solid status of VS. There was a positive relationship between signal intensity of the labyrinth and speech discrimination scores on audiogram. [ABSTRACT FROM AUTHOR]

This study aimed to determine the incidence, pattern, and etiology of dissociated vestibulo-ocular reflex (VOR) function according to the stimulus frequency in dizzy patients. We retrospectively evaluated the results of bithermal caloric tests and video-head impulse tests (vHITs) in 1022 patients with dizziness or vertigo between July 2016 and April 2021. Patients were classified into concordant group (normal or abnormal results on both tests) and discordant group (dissociated results between two tests). Of 1022 patients, discordant group had 159 (16%), comprising abnormal horizontal vHITs with normal caloric responses (n = 36, 23%) and abnormal caloric tests with normal horizontal vHITs (n = 123, 77%). The former group showed similar frequency of peripheral (44%) and central (42%) causes, and more common involvement of bilateral horizontal semicircular canals in central than peripheral causes (86.7 vs 37.5%, p = 0.005). The most common peripheral causes were Meniere's disease and chronic vestibular neuritis, while central causes were variable, but mainly affecting the cerebellum. In the latter group, peripheral causes were common (67%), with the main etiologies being Meniere's disease and vestibular neuritis, whereas central causes were found in only 5%. The degree of canal paresis did not differ significantly between patients with central and peripheral causes. Discordant VOR function according to the stimulus frequency was not uncommon in dizzy patients. Specific patterns of VOR dissociation according to the disease etiologies may offer insight into underlying pathophysiology. [ABSTRACT FROM AUTHOR]

Background: It is generally accepted that headshake nystagmus (HSN) is generated from an asymmetrical peripheral vestibular input and a correlation exists between HSN and canal paresis. There have been limited reports, however, how HSN correlates with the more recently introduced tests of vestibular function. Aims/objectives: To evaluate the correlation between HSN and unilateral weakness on caloric testing, high-frequency vestibulo-ocular reflex (VOR) function on video head impulse testing (VHIT) and otolith function determined by vestibular evoked myogenic potentials (VEMPs). Methods: A retrospective study of all patients who underwent complete vestibular function testing at our tertiary referral center from 2016 to 2019 was performed. Demographic data, clinical diagnosis (where available), the results of video-nystagmography, vHIT, and VEMPs were evaluated. Results: Of the 1499 patients in the study period, 101 (6.7%) had HSN. Vestibular test abnormalities were more common in patients with HSN. The sensitivity of HSN for underlying pathology was low in comparison with vestibular testing. However, HSN demonstrated a high specificity. Conclusions and significance: HSN generation is likely more complex than caloric-induced nystagmus, probably due to additional variables within the vestibular system. HSN may provide clinicians with additional information concerning high-frequency VOR function involving lateral semicircular and otolith dysfunction. [ABSTRACT FROM AUTHOR]

Background: To investigate the association between disease duration and the severity of bilateral vestibulopathy in individuals with complete or incomplete CANVAS (Cerebellar Ataxia with Neuropathy and Vestibular Areflexia Syndrome) and biallelic RFC1 repeat expansions. Methods: Retrospective analysis of clinical data and the vestibulo‐ocular reflex quantified by the video head impulse test in 20 patients with confirmed biallelic RFC1 repeat expansions. Results: Vestibulo‐ocular reflex gain at first admittance 6.9 ± 5.0 years after disease onset was 0.16 [0.15–0.31] (median [interquartile range]). Cross‐sectional analysis revealed that gain reduction was associated with disease duration. Follow‐up measurements were available for ten individuals: eight of them exhibited a progressive decrease of the vestibulo‐ocular reflex gain over time. At the first visit, six of all patients (30%) did not show clinical signs of cerebellar ataxia. Conclusions: Our data suggest a pathological horizontal head impulse test, which can easily be obtained in many outpatient clinics, as a sign of bilateral vestibulopathy in genetically confirmed CANVAS that can precede clinically accessible cerebellar ataxia at least in a subset of patients. The presumably continuous decline over time possibly reflects the neurodegenerative character of the disease. Thus, genetic testing for RFC1 mutations in (isolated) bilateral vestibulopathy might allow disease detection before the onset of cerebellar signs. Further studies including a wider spectrum of vestibular function tests are warranted in a prospective design. [ABSTRACT FROM AUTHOR]

Objective: Vestibulo-ocular reflex gain at 40, 60, and 80 ms following the head movement start is calculated as the instantaneous gain. The purpose of this study was to investigate the reliability of instantaneous gain values at 40, 60, and 80 ms with testing and retesting in healthy adults. Methods: The study was conducted with Interacoustics EyeSeeCam vHIT (Interacoustics, Denmark), and 42 healthy adults were evaluated twice at half-hour intervals (test and retest) by the same practitioner. Agreement of mean gain, gain asymmetry, and instantaneous gain was evaluated using a paired samples t-test. Results: Mean age of the participants was 33.62±11.17; 38.1% were male and 61.9% were female. In the degree of the agreement, paired sample correlation (r) between test and retest results of the horizontal semicircular canals was found to be higher than those of the vertical semicircular canals. Moreover, the highest correlation between test and retest for instantaneous gain, calculated for only horizontal semicircular canals, was found at 80 ms on each side (0.791; 0.838, right and left, respectively), while the lowest correlation between these parameters was found between the gain asymmetry values. Conclusion: The video head impulse test used in studies calculates the mean gain in approximately at 60 ms. However, the higher correlation between mean gain values at 80 ms in our findings indicates that gain calculation strategies and techniques for latencies should be discussed. Additionally, the low correlation of vertical semicircular canals for mean gain and gain asymmetry between semicircular canal pairs, which clearly shows that more standard and more reliable methods should be developed. [ABSTRACT FROM AUTHOR]

Objective: To compare video head impulse test (vHIT) and caloric test efficacy in decompensated and compensated vertigo patients and to further investigate whether vHIT alone can be used as a diagnostic tool in vertigo. Methods: This study included 25 patients diagnosed with vertigo and without any previous history of vertigo or hearing loss before their admission to our clinic. The control group consisted of 16 healthy adult volunteers. Patients were classified into 2 groups, compensated and decompensated. Video head impulse test and caloric tests were performed and the results were compared between the groups. Results: The difference of caloric test values between control-compensated groups and compensated-decompensated groups was statistically significant (P <.001, Pearson χ2). However, there was no statistically significant difference between the compensated and control groups according to vHIT gain asymmetry values (P =.087). In the very early stages of the disease with spontaneous nystagmus, the diagnostic significance of vHIT was similar to that of the caloric test. When both sides were compared, vHIT gain asymmetry values were close to the caloric test asymmetry values. In the compensated stage, caloric test was superior to vHIT in differentiating compensated vestibular pathologies. When vHIT sensitivity was evaluated according to the bi-thermal caloric test results, the sensitivity of the vHIT gain asymmetry value was 85.71% and 23.08% for decompensated and compensated patients respectively. Conclusion: In the early decompensated stages of the disease with spontaneous nystagmus, vHIT shows similar diagnostic accuracy to that of the caloric test. Since patients can tolerate vHIT more easily, our results suggest that vHIT can be considered as a primary evaluation method in the early (decompensated) period of the disease and should be preferred over the caloric test during the acute phase. Caloric test is more reliable at the compensated stage. Video head impulse test is inadequate in evaluating the compensated vestibular hypofunctional states after compensation has been restored. Level of Evidence: Level 2b [ABSTRACT FROM AUTHOR]

Since usefulness of power spectra (PS) analysis was demonstrated in many fields of electrophysiology, the aims of the present study were to evaluate differences in frequency domain values of eye velocity traces between a group of 60 healthy subjects (HC) and 35 matched superior vestibular neuritis (VN) patients and to determine prognostic aspects of such values in terms of superior VN recovery. PS calculated on video head impulse test traces was compared between HC and during the acute stage of vertigo (T1) and after 3 months (T2) in superior VN patients. A multiple regression and desirability model between Δ (T2gain - T1gain) vestibulo-ocular reflex (VOR) gain and five prognostic factors were employed. Significant PS differences within the 7.8-16.6 Hz domain were found between superior VN and HC. A significant negative correlation was found between the 7.8-16.6 Hz domain unitary PS value and Δ VOR gain (β = - 0.836). The desirability model depicted a cutoff value of the unitary PS equal to 1.82 in order to obtain a Δ VOR gain rate at least equal to 0.1. Present findings could be a further step for monitoring those superior VN patients with systemic risk factors and high risk of VOR incomplete recovery. Graphical abstract In the top left, healthy control (HC) and superior vestibular neuritis (VN) subjects were screened by means of video head impulse test. In the top right, significant differences in power spectra values were depicted within the 7.8-16.6 Hz domain when comparing the two groups of subjects. In the bottom center, the desirability model depicts a cutoff value of the power spectra equal to 1.82 in order to obtain a Δ vestibulo-ocular reflex gain rate at least equal to 0.1. [ABSTRACT FROM AUTHOR]

Objective: The goal of this study was to determine the sensitivity and specificity of some widely used, easily administered clinical tests. Background: Simple tests of oculomotor function have become widely used for clinical screening of patients suspected of having vestibular disorders despite a paucity of evidence showing good statistical support for their use in this highly variable population. Methods: Healthy controls with no history of otologic or neurologic disorders (n = 291) were compared to patients with known vestibular disorders (n = 62). All subjects performed passive and active head shaking, un-instrumented head impulse tests (HT), and video head impulse tests (vHIT) recorded with infrared video-oculography. Results: For both passive and active head shaking, using presence/absence of vertigo and of nystagmus, sensitivity was low (<0.40). Sensitivity of presence/absence of saccades on HT was even lower (<0.15). On vHIT, gains were all approximately = 1.0, so sensitivity was very low (approximately 0.15-0.35). Sensitivity and specificity for presence/absence of saccades were moderately poor (less than 0.70). Conclusion: None of these tests are adequate for screening patients in the out-patient clinic for vestibular disorders or for screening people in epidemiologic studies to determine the prevalence of vestibular disorders. [ABSTRACT FROM AUTHOR]

Objective: The goal of this study was to determine the sensitivity and specificity of some widely used, easily administered clinical tests. Background: Simple tests of oculomotor function have become widely used for clinical screening of patients suspected of having vestibular disorders despite a paucity of evidence showing good statistical support for their use in this highly variable population. Methods: Healthy controls with no history of otologic or neurologic disorders (n=291) were compared to patients with known vestibular disorders (n=62). All subjects performed passive and active head shaking, un-instrumented head impulse tests (HT), and video head impulse tests (vHIT) recorded with infrared video-oculography. Results: For both passive and active head shaking, using presence/absence of vertigo and of nystagmus, sensitivity was low (<0.40). Sensitivity of presence/absence of saccades on HT was even lower (<0.15). On vHIT, gains were all approximately=1.0, so sensitivity was very low (approximately 0.15-0.35). Sensitivity and specificity for presence/absence of saccades were moderately poor (less than 0.70). Conclusion: None of these tests are adequate for screening patients in the out-patient clinic for vestibular disorders or for screening people in epidemiologic studies to determine the prevalence of vestibular disorders. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the lateralization value of video head-impulse test (vHIT) for the diagnosis of vestibulopathy and to analyze cases showing dissociated results with caloric test.Methods: In total, 19 healthy volunteers and 92 dizzy patients who underwent both a caloric test and a vHIT were enrolled. Patients were divided into two groups depending on their fluctuating pattern of vertigo. The vestibulo-ocular reflex (VOR) gain and gain asymmetry (GA) of a vHIT as well as unilateral weakness (UW) and the sum of the slow-phase velocities (SPVs) of warm and cold irrigation of the same side were compared. A cutoff value of VOR gain of a vHIT was also calculated using a receiver-operating characteristic curve.Results: A VOR gain in an affected ear and GA of a vHIT showed a statistically significant correlation with UW in a caloric test. The cutoff value of a vHIT was determined to be 0.875, derived under the assumption that UW of a caloric test ≤25% is normal. However, the parameters of the two tests were dissociated in 18%.Conclusion: A VOR gain of vHIT is a valuable objective parameter with a lateralization value determining vestibular hypofunction. However, considering substantial dissociation between a vHIT and a caloric test, these tests can be complementary tools for the lateralization of vestibular impairment for the comprehensive evaluation of patients' VOR. [ABSTRACT FROM AUTHOR]

Background/aims: Unsteadiness in the elderly is a frequent complaint and a strong predictor of falls and psychological distress. Although there is a general consensus that it is a multifactorial condition, recent studies have focused on the role of aging of the vestibular system as a possible cofactor. The aim of our work was to assess horizontal canal function in the elderly.Methods: We evaluated the gain of horizontal vestibulo-ocular reflex (VOR) with a video head impulse test on a sample of 58 subjects aged >70 years without lifetime episodes of vertigo and correlated the value with different clinical conditions (hypertension, diabetes, prior cardiovascular and vascular disorders of the central nervous system, and falls).Results: The mean value of the gain was 0.86 ± 0.12, and people aged between 70 and 80 years presented higher values (0.90 ± 0.1) compared to those >80 years (0.81 ± 0.13; p = 0.025). Previous vascular disorders of the central nervous system were a predictor of decreased VOR gain (p = 0.0003). A nonparametric analysis demonstrated that sex, age, and VOR gain (p ˂ 0.0001) were predictive of falls.Conclusions: Our data support the hypothesis of a decrease of VOR gain in the elderly. The decrease of canal function may therefore play a role in the risk of falls in the elderly. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Globally, there are 3 million people living with multiple sclerosis (PLW-MS). A large proportion of PLW-MS have abnormal vestibular function tests that suggest central vestibular lesions. Yet, data regarding vestibular-ocular control in PLW-MS is limited. Thus, we aimed to further characterize compensatory saccade (CS) behavior in PLW-MS. We analyzed video head impulse data from four groups of six age- and sex-matched adults: people living with mild MS (PLW-mild-MS, people living with moderate MS (PLW-moderate-MS), people living with unilateral vestibular deafferentation (PLW-UVD), and healthy controls (HC). PLW-moderate-MS had lower lateral canal vestibulo-ocular reflex (VOR) gain bilaterally compared to PLW-mild MS (p < 0.001), HC (p < 0.001), and PLW-UVD (p < 0.001). CS frequency was higher for impulses towards the less affected side in PLW-moderate-MS versus the more (p = 0.01) and less (p < 0.001) affected sides in PLW-mild-MS. CS latency was shorter (p < 0.001) and CS peak velocity was lower (p < 0.001) with impulses towards the more affected side versus the less affected side in PLW-moderate-MS. However, CS peak velocity with impulses towards each side was similar in PLW-mild-MS (p = 0.12). Gaze position error (GPE) was larger after impulses towards the more affected side versus the less affected side in PLW-moderate-MS (p < 0.001) and PLW-mild-MS (p < 0.001). MS-related disability was moderately associated with VOR gain (p < 0.001) and GPE (p < 0.001). Additionally, we identified micro-saccades and position correcting saccades that were uniquely employed by PLW-MS as compensatory gaze stabilizing strategies. In PLW-MS, the characteristics of compensatory oculomotor behavior depend on the extent of residual VOR gain. [Display omitted] • People living with moderate multiple sclerosis often fail to generate compensatory saccades. • People living with mild multiple sclerosis tend to over-compensate for gaze position error. • The absence of saccades to compensate for low VOR gain may suggest internuclear ophthalmoplegia. [ABSTRACT FROM AUTHOR]

Background: The observation or measurement of eye movement can aid in the detection and localization of vestibular pathology due to the relationship between the function of the vestibular sensory receptors in the inner ear and the eye movements produced by the vestibulo-ocular reflex (VOR). The majority of bedside and laboratory tests of vestibular function involve the observation or measurement of horizontal eye movements (i.e., horizontal VOR) produced by stimuli that activate the horizontal semicircular canals (SCCs) and the superior vestibular nerve. The video head impulse test (vHIT) is a new clinical test of dynamic SCO function that uses a high-speed digital video camera to record head and eye movement during and immediately after passive head rotations. The SYNAPSYS Inc. vHIT device measures the “canal deficit” (deviation in gaze) during passive head impulses in the horizontal and diagonal (vertical) planes. There is, however, a paucity of data that has been reported using this device. Purpose: The purpose of this study was to obtain normative data and assess the test-retest reliability of the SYNAPSYS vHIT (version 2.0). Research Design: A prospective repeated measures design was utilized. Study Sample: Thirty young adults with normal hearing, normal caloric test results, and a negative history of vestibular disorder, neurological disease, open or closed head injury, or cervical spine injury participated in the study. Data Collection and Analysis: A single examiner manually rotated each participant’s head in the horizontal and diagonal planes in two directions (left and right in the horizontal plane; downward and upward in each diagonal plane) resulting in the stimulation of each of the six SCCs. Each participant returned for repeat testing to assess test-retest reliability. The effects of ear, session, and semicircular canal (horizontal, anterior, posterior) on the magnitude of canal deficit during the vHIT were assessed using repeated measures analysis of variance. Results: The mean canal deficit of the horizontal canals (8.3%) was significantly lower than the mean canal deficit of the anterior canals (16.5%) and the posterior canals (15.2%); there was no significant difference between the mean canal deficits of the anterior and posterior canals. The main effects of session and ear on canal deficit were not significant, and there were no significant interaction effects. There was no significant difference between the mean canal deficit for session 1 and session 2 for the horizontal, anterior, and posterior canals. The 95th percentiles for canal deficit were 19, 26, and 22% for the horizontal, anterior, and posterior SCCs, respectively. Conclusions: Testing of all six SCCs was completed in most participants in ~10 min and was well-tolerated. The vHIT has some important advantages relative to more established laboratory tests of horizontal SCC function including the ability to assess the vertical SCCs, lower cost, shorter test time, greater portability, minimal space requirements, and increased patient comfort. Additional data, however, should be obtained from older participants with normal vestibular function and from patients with vestibular disorders. Within-subject comparisons between the results of the vHIT and the caloric and rotary chair tests will be important in determining the role of the vHIT in the vestibular test battery. [ABSTRACT FROM AUTHOR]

The video head impulse test (vHIT) is a diagnostic tool to examine patients experiencing dizziness by assessing the function of the semicircular canals. vHIT has been widely studied in adults but relatively less so in children. The aim of this study was to evaluate the causes of dizziness and the results of vHIT in children. We also identified factors that affect the vHIT results such as artifacts and technical errors. Retrospective review; Tertiary care center. A total of 39 patients who visited our clinic for dizziness from 2014 to 2017. The gain of vestibulo-ocular reflex, refixation saccades, and artifacts were analyzed using vHIT. We analyzed 691 individual vHIT traces and categorized the artifacts into 8 categories. Twenty-three males and 16 females were included. The mean age was 13.84 ± 2.60 years (range, 7–18). Common causes of dizziness were benign paroxysmal vertigo of childhood (25.6%), vestibular neuritis (20.5%), and vestibular migraine (17.9%). The sensitivity and specificity of vHIT based on the bithermal caloric test results were 40% and 94%, respectively. The analysis of vHIT traces revealed that the children had higher artifact ratios of vHIT than the adults. The main artifacts were high gain and blinking eyes. The vHIT results showed a higher percentage of artifacts in children than in the adults. More careful efforts are required to obtain more accurate results during the test, and it is necessary to check for technical errors while interpreting the results. [ABSTRACT FROM AUTHOR]