VOR gain calculation methods in video head impulse recordings.
Ontology highlight
ABSTRACT: Background
International consensus on best practices for calculating and reporting vestibular function is lacking. Quantitative vestibulo-ocular reflex (VOR) gain using a video head impulse test (HIT) device can be calculated by various methods.Objective
To compare different gain calculation methods and to analyze interactions between artifacts and calculation methods.Methods
We analyzed 1300 horizontal HIT traces from 26 patients with acute vestibular syndrome and calculated the ratio between eye and head velocity at specific time points (40 ms, 60 ms) after HIT onset ('velocity gain'), ratio of velocity slopes ('regression gain'), and ratio of area under the curves after de-saccading ('position gain').Results
There was no mean difference between gain at 60 ms and position gain, both showing a significant correlation (r2 = 0.77, p < 0.001) for artifact-free recordings. All artifacts reduced high, normal-range gains modestly (range -0.06 to -0.11). The impact on abnormal, low gains was variable (depending on the artifact type) compared to artifact-free recordings.Conclusions
There is no clear superiority of a single gain calculation method for video HIT testing. Artifacts cause small but significant reductions of measured VOR gains in HITs with higher, normal-range gains, regardless of calculation method. Artifacts in abnormal HITs with low gain increased measurement noise. A larger number of HITs should be performed to confirm abnormal results, regardless of calculation method.
SUBMITTER: Zamaro E
PROVIDER: S-EPMC9037838 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Background/hypothesisThe video Head Impulse Test (vHIT) is now widely used to test the function of each of the six semicircular canals individually by measuring the eye rotation response to an abrupt head rotation in the plane of the canal. The main measure of canal adequacy is the ratio of the eye movement response to the head movement stimulus, i.e., the gain of the vestibulo-ocular reflex (VOR). However, there is a need for normative data about how VOR gain is affected by age and also by head velocity, to allow the response of any particular patient to be compared to the responses of healthy subjects in their age range. In this study, we determined for all six semicircular canals, normative values of VOR gain, for each canal across a range of head velocities, for healthy subjects in each decade of life.Study designThe VOR gain was measured for all canals across a range of head velocities for at least 10 healthy subjects in decade age bands: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89.MethodsThe compensatory eye movement response to a small, unpredictable, abrupt head rotation (head impulse) was measured by the ICS impulse prototype system. The same operator delivered every impulse to every subject.ResultsVestibulo-ocular reflex gain decreased at high head velocities, but was largely unaffected by age into the 80- to 89-year age group. There were some small but systematic differences between the two directions of head rotation, which appear to be largely due to the fact that in this study only the right eye was measured. The results are considered in relation to recent evidence about the effect of age on VOR performance.ConclusionThese normative values allow the results of any particular patient to be compared to the values of healthy people in their age range and so allow, for example, detection of whether a patient has a bilateral vestibular loss. VOR gain, as measured directly by the eye movement response to head rotation, seems largely unaffected by aging.
| S-EPMC4495346 | biostudies-literature
Project description:Background and objectiveMigraine is an extremely prevalent primary headache disorder that frequently associates parallel symptoms such as dizziness, tinnitus and hearing loss. Our aim is to investigate differences in video head impulse (vHIT) results with patients suffering from vestibular migraine (VM) and healthy people, taking into consideration mean values of vestibule ocular reflex (VOR) gain, occurrence of the compensatory saccades latency and amplitude. According to the results, determine the usefulness of vHIT in vestibular migraine diagnostics.MethodsA total number of 120 subjects were enrolled in the study, 80 of them were vestibular migraine patients (VM), while the other 40 were a control group of age matched healthy subjects. History was taking during the evaluation; videonystagmography and the video head impulse test were done.ResultsThe rate of saccades is much more higher in the VM group compared to the healthy subjects group, only 7.5% of the VM group showed a low VOR gain with compensatory saccades denoting a vestibular deficit.ConclusionThe refixation saccades are an important sign that could underlie different vestibular problems. vHIT result can contribute to the completion of full mosaic of vestibular migraine diagnostics.
| S-EPMC6291630 | biostudies-literature
Project description:The video head impulse test (HIT) measures vestibular function (vestibulo-ocular reflex [VOR] gain - ratio of eye to head movement), and, in principle, could be used to make a distinction between central and peripheral causes of vertigo. However, VOG recordings contain artifacts, so using unfiltered device data might bias the final diagnosis, limiting application in frontline healthcare settings such as the emergency department (ED). We sought to assess whether unfiltered data (containing artifacts) from a video-oculography (VOG) device have an impact on VOR gain measures in acute vestibular syndrome (AVS).This cross-sectional study compared VOG HIT results 'unfiltered' (standard device output) versus 'filtered' (artifacts manually removed) and relative to a gold standard final diagnosis (neuroimaging plus clinical follow-up) in 23 ED patients with acute dizziness, nystagmus, gait disturbance and head motion intolerance.Mean VOR gain assessment alone (unfiltered device data) discriminated posterior inferior cerebellar artery (PICA) strokes from vestibular neuritis with 91% accuracy in AVS. Optimal stroke discrimination cut points were bilateral VOR gain?>0.7099 (unfiltered data) versus?>0.7041 (filtered data). For PICA stroke sensitivity and specificity, there was no clinically-relevant difference between unfiltered and filtered data-sensitivity for PICA stroke was 100% for both data sets and specificity was almost identical (87.5% unfiltered versus 91.7% filtered). More impulses increased gain precision.The bedside HIT remains the single best method for discriminating between vestibular neuritis and PICA stroke in patients presenting AVS. Quantitative VOG HIT testing in the ED is associated with frequent artifacts that reduce precision but not accuracy. At least 10-20 properly-performed HIT trials per tested ear are recommended for a precise VOR gain estimate.
| S-EPMC6054448 | biostudies-literature
Project description:BackgroundThe head impulse test (HIT) is a useful bedside test to identify peripheral vestibular deficits. However, such a deficit of the vestibulo-ocular reflex (VOR) may not be diagnosed because corrective saccades cannot always be detected by simple observation. The scleral search coil technique is the gold standard for HIT measurements, but it is not practical for routine testing or for acute patients, because they are required to wear an uncomfortable contact lens.ObjectiveTo develop an easy-to-use video HIT system (vHIT) as a clinical tool for identifying peripheral vestibular deficits. To validate the diagnostic accuracy of vHIT by simultaneous measures with video and search coil recordings across healthy subjects and patients with a wide range of previously identified peripheral vestibular deficits.MethodsHorizontal HIT was recorded simultaneously with vHIT (250 Hz) and search coils (1,000 Hz) in 8 normal subjects, 6 patients with vestibular neuritis, 1 patient after unilateral intratympanic gentamicin, and 1 patient with bilateral gentamicin vestibulotoxicity.ResultsSimultaneous video and search coil recordings of eye movements were closely comparable (average concordance correlation coefficient r(c) = 0.930). Mean VOR gains measured with search coils and video were not significantly different in normal (p = 0.107) and patients (p = 0.073). With these groups, the sensitivity and specificity of both the reference and index test were 1.0 (95% confidence interval 0.69-1.0). vHIT measures detected both overt and covert saccades as accurately as coils.ConclusionsThe video head impulse test is equivalent to search coils in identifying peripheral vestibular deficits but easier to use in clinics, even in patients with acute vestibular neuritis.
| S-EPMC2890997 | biostudies-literature
Project description:BackgroundThe video head impulse test (vHIT) is a useful clinical tool to detect semicircular canal dysfunction. However vHIT has hitherto been limited to measurement of horizontal canals, while scleral search coils have been the only accepted method to measure head impulses in vertical canals. The goal of this study was to determine whether vHIT can detect vertical semicircular canal dysfunction as identified by scleral search coil recordings.MethodsSmall unpredictable head rotations were delivered by hand diagonally in the plane of the vertical semicircular canals while gaze was directed along the same plane. The planes were oriented along the left-anterior-right-posterior (LARP) canals and right-anterior-left-posterior (RALP) canals. Eye movements were recorded simultaneously in 2D with vHIT (250 Hz) and in 3D with search coils (1000 Hz). Twelve patients with unilateral, bilateral and individual semicircular canal dysfunction were tested and compared to seven normal subjects.ResultsSimultaneous video and search coil recordings were closely comparable. Mean VOR gain difference measured with vHIT and search coils was 0.05 (SD?=?0.14) for the LARP plane and -0.04 (SD?=?0.14) for the RALP plane. The coefficient of determination R(2) was 0.98 for the LARP plane and 0.98 for the RALP plane and the results of the two methods were not significantly different. vHIT and search coil measures displayed comparable patterns of covert and overt catch-up saccades.ConclusionsvHIT detects dysfunction of individual vertical semicircular canals in vestibular patients as accurately as scleral search coils. Unlike search coils, vHIT is non-invasive, easy to use and hence practical in clinics.
| S-EPMC3632590 | biostudies-literature
Project description:Introduction We are now able to detect abnormalities for any semicircular canal with the use of the video head impulse test (vHIT). Prior to the vHIT, the gold standard for unilateral canal paresis of the lateral canal was considered the caloric test. Clinical cases where the caloric test and vHIT are discordant are not uncommon. Methods Retrospective study. All consecutive cases of dizziness seen from 11/2020 to 12/2021 for which the patient underwent both caloric and vHIT tests performed within 10 days, were reviewed. Patients with discordant results were included. We evaluated the caloric response, vHIT gains for all canals and saccades, with and without gain abnormalities. Results We included 74 cases of dizziness with dissociated results. The most common finding was a normal caloric response with abnormal vHIT results (60.8%); the main abnormal finding on vHIT was the presence of saccades. In this group, 37.7% of patients had normal gains and refixation saccades. In addition, the most found low gain was for the posterior canal. The main diagnosis in this group was vestibular migraine. For the group with unilateral caloric paresis and normal vHIT gain in the lateral canal, the main diagnosis was Ménière's disease. Discussion The most common disorders with discordant results were Ménière's disease and vestibular migraine. The caloric test and vHIT are complementary and combining both tests provide greater clinical information. Further research is needed to understand refixation saccades with normal gains.
| S-EPMC9548977 | biostudies-literature
Project description:BackgroundWe propose a Suppression Head IMPulse (SHIMP) test method that provides for equipment only through the use of InfraRed Video-OculoScopy (IR-VOS) and allows horizontal and vertical semicircular canal function evaluation in bedside mode. We therefore named the test InfraRed clinical SHIMP (IR-cSHIMP).MethodsTo check IR-cSHIMP diagnostic efficiency, we studied 22 normal subjects, 18 patients with unilateral, and 6 with bilateral deficient vestibulopathy. Each subject first underwent a vestibular examination and, only later, an IRc-SHIMP test.ResultsWhen the IR-cSHIMP test was performed in the horizontal plane, all normal subjects showed anti-compensatory saccades. When the vertical semicircular canal function was evaluated, the same result was obtained in all normal subjects except three, which were considered false positives. In patients with vestibular deficits, the test performed in the horizontal and vertical planes were always pathological, with 100% agreement between clinical and instrumental tests.ConclusionsOur bedside method proved to be fast, simple, and effective in discriminating between healthy and pathological subjects. It required only the same skill as the better-known cHIT. For these reasons, we believe that the IR-cSHIMP should be part of daily clinical practice as a useful tool in the selection of patients to undergo more sophisticated investigations.
| S-EPMC10886088 | biostudies-literature
Project description:The video head impulse test (VHIT) is widely used to identify semicircular canal function impairments in adults. But classical VHIT testing systems attach goggles tightly to the head, which is not tolerated by infants. Remote video detection of head and eye movements resolves this issue and, here, we report VHIT protocols and normative values for children. Vestibulo-ocular reflex (VOR) gain was measured for all canals of 303 healthy subjects, including 274 children (aged 2.6 months-15 years) and 26 adults (aged 16-67). We used the Synapsys® (Marseilles, France) VHIT Ulmer system whose remote camera measures head and eye movements. HITs were performed at high velocities. Testing typically lasts 5-10 min. In infants as young as 3 months old, VHIT yielded good inter-measure replicability. VOR gain increases rapidly until about the age of 6 years (with variation among canals), then progresses more slowly to reach adult values by the age of 16. Values are more variable among very young children and for the vertical canals, but showed no difference for right versus left head rotations. Normative values of VOR gain are presented to help detect vestibular impairment in patients. VHIT testing prior to cochlear implants could help prevent total vestibular loss and the resulting grave impairments of motor and cognitive development in patients with residual unilateral vestibular function.
| S-EPMC5594068 | biostudies-literature
Project description:We sought to quantify and compare angular vestibulo-ocular reflex (aVOR) gain and compensatory saccade properties elicited by the head impulse test (HIT) in pontine-cerebellar stroke (PCS) and vestibular neuritis (VN).Horizontal HIT was recorded ?7 days from vertigo onset with dual-search coils in 33 PCS involving the anterior inferior, posterior inferior, and superior cerebellar arteries (13 AICA, 17 PICA, 3 SCA) confirmed by MRI and 20 VN. We determined the aVOR gain and asymmetry, and compensatory overt saccade properties including amplitude asymmetry and cumulative amplitude (ipsilesional trials [I]; contralesional trials [C]).The aVOR gain (normal: 0.96; asymmetry = 2%) was bilaterally reduced, greater in AICA (I = 0.39, C = 0.57; asymmetry = 20%) than in PICA/SCA strokes (I = 0.75, C = 0.74; asymmetry = 7%), in contrast to the unilateral deficit in VN (I = 0.22, C = 0.76; asymmetry = 54%). Cumulative amplitude (normal: 1.1°) was smaller in AICA (I = 4.2°, C = 3.0°) and PICA/SCA strokes (I = 2.1°, C = 3.0°) compared with VN (I = 8.5°, C = 1.3°). Amplitude asymmetry in AICA and PICA/SCA strokes was comparable, but favored the contralesional side in PICA/SCA strokes and the ipsilesional side in VN. Saccade asymmetry <61% was found in 97% of PCS and none of VN. Gain asymmetry <40% was found in 94% of PCS and 10% of VN.HIT gains and compensatory saccades differ between PCS and VN. VN was characterized by unilateral gain deficits with asymmetric large saccades, AICA stroke by more symmetric bilateral gain reduction with smaller saccades, and PICA stroke by contralesional gain bias with the smallest saccades. Saccade and gain asymmetry should be investigated further in future diagnostic accuracy studies.This study provides Class II evidence that aVOR testing accurately distinguishes patients with PCS from VN (sensitivity 94%-97%, specificity 90%-100%).
| S-EPMC4222852 | biostudies-other
Project description:BackgroundVideo head impulse tests (vHITs), assessing the vestibulo-ocular reflex (VOR), may be helpful in the differential diagnosis of acute dizziness. We aimed to investigate vHITs in patients with acute posterior circulation stroke (PCS) to examine whether these findings could exhibit significant abnormalities based on lesion locations, and to evaluate diagnostic value of vHIT in differentiating dizziness between PCS and vestibular neuritis (VN).MethodsWe prospectively recruited consecutive 80 patients with acute PCS and analyzed vHIT findings according to the presence of dorsal brainstem stroke (DBS). We also compared vHIT findings between PCS patients with dizziness and a previously studied VN group (n = 29). Receiver operating characteristic (ROC) analysis was performed to assess the performance of VOR gain and its asymmetry in distinguishing dizziness between PCS and VN.ResultsPatients with PCS underwent vHIT within a median of 2 days from stroke onset. Mean horizontal VOR gain was 0.97, and there was no significant difference between PCS patients with DBS (n = 15) and without (n = 65). None exhibited pathologic overt corrective saccades. When comparing the PCS group with dizziness (n = 40) to the VN group (n = 29), patients with VN demonstrated significantly lower mean VOR gains in the ipsilesional horizontal canals (1.00 vs. 0.57, p < 0.001). VOR gain and their asymmetry effectively differentiated dizziness in the PCS from VN groups, with an area under the ROC curve of 0.86 (95% CI 0.74-0.98) and 0.91 (95% CI 0.83-0.99, p < 0.001), respectively.ConclusionSignificantly abnormal vHIT results were rare in patients with acute PCS, even in the presence of DBS. Moreover, vHIT effectively differentiated dizziness between PCS and VN, highlighting its potential for aiding differential diagnosis of acute dizziness.
| S-EPMC10557255 | biostudies-literature