HITCal: a software tool for analysis of video head impulse test responses

Rey-Martínez, Jorge; Batuecas‐Caletrío, Ángel; Matiñó, Eusebi; Pérez-Fernández, Nicolas

doi:10.3109/00016489.2015.1035401

Cited by 54 publications

(43 citation statements)

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“…Some studies have reported that the trial by trial variability in saccade latency (clustering) is related to vestibular compensation and rehabilitation [58,59,62]. We found that saccade clustering is strongly related to visual input but only weakly related to vestibular input (Fig 8), signifying that saccade clustering better represents visual substitution than vestibular compensation.…”

Section: Discussionmentioning

confidence: 59%

Head impulse compensatory saccades: Visual dependence is most evident in bilateral vestibular loss

et al. 2020

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The normal vestibulo-ocular reflex (VOR) generates almost perfectly compensatory smooth eye movements during a 'head-impulse' rotation. An imperfect VOR gain provokes additional compensatory saccades to re-acquire an earth-fixed target. In the present study, we investigated vestibular and visual contributions on saccade production. Eye position and velocity during horizontal and vertical canal-plane head-impulses were recorded in the light and dark from 16 controls, 22 subjects after complete surgical unilateral vestibular deafferentation (UVD), eight subjects with idiopathic bilateral vestibular loss (BVL), and one subject after complete bilateral vestibular deafferentation (BVD). When impulses were delivered in the horizontal-canal plane, in complete darkness compared with light, first saccade frequency mean(SEM) reduced from 96.6(1.3)-62.3(8.9) % in BVL but only 98.3(0.6)-92.0 (2.3) % in UVD; saccade amplitudes reduced from 7.0(0.5)-3.6(0.4)˚in BVL but were unchanged 6.2(0.3)-5.5(0.6)˚in UVD. In the dark, saccade latencies were prolonged in lesioned ears, from 168(8.4)-240(24.5) ms in BVL and 177(5.2)-196(5.7) ms in UVD; saccades became less clustered. In BVD, saccades were not completely abolished in the dark, but their amplitudes decreased from 7.3-3.0˚and latencies became more variable. For unlesioned ears (controls and unlesioned ears of UVD), saccade frequency also reduced in the dark, but their small amplitudes slightly increased, while latency and clustering remained unchanged. First and second saccade frequencies were 75.3(4.5) % and 20.3(4.1) %; without visual fixation they dropped to 32.2(5.0) % and 3.8(1.2) %. The VOR gain was affected by vision only in unlesioned ears of UVD; gains for the horizontal-plane rose slightly, and the

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Section: Discussionmentioning

confidence: 59%

Head impulse compensatory saccades: Visual dependence is most evident in bilateral vestibular loss

et al. 2020

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“…A high PR score result (near 100) means maximum scattered, poor grouped responses. HITCal software development process and source code, and PR score algorithm and methodology have been previously published by our research group (7) (Figure 1; Table 1). …”

Section: Methodsmentioning

confidence: 99%

“…Using this method, saccades can be divided into two groups yielding either isochronic impulses (final look of the response is gathered) or asynchronic impulses (final look is scattered) (7). Interestingly, when the organization patterns of refixation saccades are considered, the scattered response correlates well with an uncompensated vestibular deficit in patients after surgery for a vestibular schwannoma and the gathered with a better clinical compensation (8).…”

Section: Introductionmentioning

confidence: 99%

Vestibulo-Ocular Reflex Stabilization after Vestibular Schwannoma Surgery: A Story Told by Saccades

et al. 2017

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ObjectiveTo evaluate vestibular compensation via measurement of the vestibulo-ocular reflex (VOR) following vestibular schwannoma surgery and its relationship with changes in saccades strategy after surgery.PatientsThirty-six consecutive patients with vestibular schwannomas, without brainstem compression, underwent surgical resection. Patients were recruited from University Hospital of Salamanca, Spain.MethodsWe assessed the age, sex, tumor size, degree of canalicular weakness, and preoperative video head impulse test (gain and saccade organization measured with PR score). Gain and saccade organization were compared with postoperative values at discharge and also at 1, 3, and 6 months. PR scores are a measure of the scatter of refixation saccades.ResultsPatients with normal preoperative caloric function had higher PR scores (saccades were scattered) following surgery compared to patients with significant preoperative canal paresis (p < 0.05). VOR gain and the presence of covert/overt saccades preoperatively did not influence the PR score (p > 0.05), but a group of patients with very low VOR gain (<0.45) and covert/overt saccades before surgery had lower PR scores after surgery. The differences after 6 months were not significant.ConclusionPatients with more severe vestibular dysfunction before vestibular schwannoma surgery show significantly faster vestibular compensation following surgery, manifested by changes in VOR gain and PR score. The scatter of compensatory saccades (as measured by the PR score) may be a surrogate early marker of clinical recovery, given its relationship to the Dizziness Handicap Inventory.

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“…As in [6], horizontal velocity VOR gain was calculated as the ratio of mean eye velocity over mean head velocity during a 40 msec window centered at the peak head acceleration. Or else, velocity VOR gain in [16] was calculated for each subject by dividing the length of the total eye velocity vector (eye speed) by the length of the head velocity vector (head speed). The disadvantage of the device that uses velocity VOR gain as patient output is that it requires a lot of careful calibration.…”

Section: Vor Gain Calculationmentioning

confidence: 99%

A Development of Clinical Decision Support System for Video Head Impulse Test Based on Fuzzy Inference System

et al. 2018

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This paper represents the clinical decision support system for video head impulse test (vHIT) based on fuzzy inference system. It examines the eye and head movement recorded by the eye movement tracking device, calculates the vestibulo-ocular reflex (VOR) gain, and applies fuzzy inference system to output the normality and artifact index of the test result. The position VOR gain and the proportion of covert and overt catch-up saccades (CUS) within the dataset are used as the input of the inference system. In addition, this system yields one more factor, the artifact index, which represents the current interference in the dataset. Data of fifteen vestibular neuritis patients and two of normal subjects were evaluated. The artifact index appears to be very high in the lesion side of vestibular neuritis (VN) patients, indicating highly theoretical contradictions, which are low gain but without CUS, or normal gain with the appearance of CUS. Both intact side and normal subject show high normality and low artifact index, even though the intact side has slightly lower normality and higher artifact index. In conclusion, this is a robust system, which is the first one that takes gain and CUS into account, to output not only the normality of the vHIT dataset, but also the artifacts.

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HITCal: a software tool for analysis of video head impulse test responses

Cited by 54 publications

References 10 publications

Head impulse compensatory saccades: Visual dependence is most evident in bilateral vestibular loss

Head impulse compensatory saccades: Visual dependence is most evident in bilateral vestibular loss

Vestibulo-Ocular Reflex Stabilization after Vestibular Schwannoma Surgery: A Story Told by Saccades

A Development of Clinical Decision Support System for Video Head Impulse Test Based on Fuzzy Inference System

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