scholarly journals Short-Latency Covert Saccades - The Explanation for Good Dynamic Visual Performance After Unilateral Vestibular Loss?

2021 ◽  
Vol 12 ◽  
Author(s):  
Julia Sjögren ◽  
Mikael Karlberg ◽  
Craig Hickson ◽  
Måns Magnusson ◽  
Per-Anders Fransson ◽  
...  
Keyword(s):  
Visual Perception ◽  
Head Movement ◽  
Position Error ◽  
Head Movements ◽  
Visual Performance ◽  
Head Impulse Test ◽  
Vestibular Loss ◽  
Intact Side ◽  
Head Impulse ◽  
Head Impulses

Background: Functional head impulse test (fHIT) tests the ability of the vestibulo-ocular reflex (VOR) to allow visual perception during head movements. Our previous study showed that active head movements to the side with a vestibular lesion generated a dynamic visual performance that were as good as during movements to the intact side.Objective: To examine the differences in eye position during the head impulse test when performed with active and passive head movements, in order to better understand the role of the different saccade properties in improving visual performance.Method: We recruited 8 subjects with complete unilateral vestibular loss (4 men and 4 women, mean age 47 years) and tested them with video Head Impulse Test (vHIT) and Functional Head Impulse Test (fHIT) during passive and active movements while looking at a target. We assessed the mean absolute position error of the eye during different time frames of the head movement, the peak latency and the peak velocity of the first saccade, as well as the visual performance during the head movement.Results: Active head impulses to the lesioned side generated dynamic visual performances that were as good as when testing the intact side. Active head impulses resulted in smaller position errors during the visual perception task (p = 0.006) compared to passive head-impulses and the position error during the visual perception time frame correlated with shorter latencies of the first saccade (p < 0.001).Conclusion: Actively generated head impulses toward the side with a complete vestibular loss resulted in a position error within or close to the margin necessary to obtain visual perception for a brief period of time in patients with chronic unilateral vestibular loss. This seems to be attributed to the appearance of short-latency covert saccades, which position the eyes in a more favorable position during head movements.

scholarly journals The Effect of Different Head Movement Paradigms on Vestibulo-Ocular Reflex Gain and Saccadic Eye Responses in the Suppression Head Impulse Test in Healthy Adult Volunteers

2021 ◽  
Vol 12 ◽  
Author(s):  
Dmitrii Starkov ◽  
Bernd Vermorken ◽  
T. S. Van Dooren ◽  
Lisa Van Stiphout ◽  
Miranda Janssen ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Healthy Adult ◽  
Head Movements ◽  
Head Impulse Test ◽  
Head Impulse ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Reflex Gain ◽  
Head Impulses ◽  
Adult Volunteers

Objective: This study aimed to identify differences in vestibulo-ocular reflex gain (VOR gain) and saccadic response in the suppression head impulse paradigm (SHIMP) between predictable and less predictable head movements, in a group of healthy subjects. It was hypothesized that higher prediction could lead to a lower VOR gain, a shorter saccadic latency, and higher grouping of saccades.Methods: Sixty-two healthy subjects were tested using the video head impulse test and SHIMPs in four conditions: active and passive head movements for both inward and outward directions. VOR gain, latency of the first saccade, and the level of saccade grouping (PR-score) were compared among conditions. Inward and active head movements were considered to be more predictable than outward and passive head movements.Results: After validation, results of 57 tested subjects were analyzed. Mean VOR gain was significantly lower for inward passive compared with outward passive head impulses (p < 0.001), and it was higher for active compared with passive head impulses (both inward and outward) (p ≤ 0.024). Mean latency of the first saccade was significantly shorter for inward active compared with inward passive (p ≤ 0.001) and for inward passive compared with outward passive head impulses (p = 0.012). Mean PR-score was only significantly higher in active outward than in active inward head impulses (p = 0.004).Conclusion: For SHIMP, a higher predictability in head movements lowered gain only in passive impulses and shortened latencies of compensatory saccades overall. For active impulses, gain calculation was affected by short-latency compensatory saccades, hindering reliable comparison with gains of passive impulses. Predictability did not substantially influence grouping of compensatory saccades.

scholarly journals Enhanced Eye Velocity With Backup Saccades in vHIT Tests of a Menière Disease Patient: A Case Report

2021 ◽  
Vol 8 ◽  
Author(s):  
Maria Montserrat Soriano-Reixach ◽  
Jorge Rey-Martinez ◽  
Xabier Altuna ◽  
Ian Curthoys
Keyword(s):  
Disease Patient ◽  
Vestibular Function ◽  
Position Error ◽  
Head Movements ◽  
Slow Phase ◽  
Head Impulse ◽  
Head Impulses ◽  
Eye Velocity ◽  
Gaze Position ◽  
Horizontal Head

Reduced eye velocity and overt or covert compensatory saccades during horizontal head impulse testing are the signs of reduced vestibular function. However, here we report the unusual case of a patient who had enhanced eye velocity during horizontal head impulses followed by a corrective saccade. We term this saccade a “backup saccade” because it acts to compensate for the gaze position error caused by the enhanced velocity (and enhanced VOR gain) and acts to return gaze directly to the fixation target as shown by eye position records. We distinguish backup saccades from overt or covert compensatory saccades or the anticompensatory quick eye movement (ACQEM) of Heuberger et al. (1) ACQEMs are anticompensatory in that they are in the same direction as head velocity and so, act to take gaze off the target and thus require later compensatory (overt) saccades to return gaze to the target. Neither of these responses were found in this patient. The patient here was diagnosed with unilateral definite Meniere's disease (MD) on the right and had enhanced VOR (gain of 1.17) for rightward head impulses followed by backup saccades. For leftwards head impulses eye velocity and VOR gain were in the normal range (VOR gain of 0.89). As further confirmation, testing with 1.84 Hz horizontal sinusoidal head movements in the visual-vestibular (VVOR) paradigm also showed these backup saccades for rightwards head turns but normal slow phase eye velocity responses without backup saccades for leftwards had turns. This evidence shows that backup saccades can be observed in some MD patients who show enhanced eye velocity responses during vHIT and that these backup saccades act to correct for gaze position error caused by the enhanced eye velocity during the head impulse and so have a compensatory effect on gaze stabilization.

Viewing Target Distance Influences the Vestibulo-Ocular Reflex Gain when Assessed Using the Video Head Impulse Test

2018 ◽  
Vol 23 (5) ◽  
pp. 285-289 ◽  
Author(s):  
Patricia Castro ◽  
Sara Sena Esteves ◽  
Florencia Lerchundi ◽  
David Buckwell ◽  
Michael A. Gresty ◽  
...  
Keyword(s):  
Head Movements ◽  
Target Distance ◽  
Head Impulse Test ◽  
Video Head Impulse Test ◽  
Gaze Stabilization ◽  
Head Impulse ◽  
Ocular Reflex ◽  
Significant Difference ◽  
Vestibulo Ocular Reflex ◽  
Reflex Gain

Gaze stabilization during head movements is provided by the vestibulo-ocular reflex (VOR). Clinical assessment of this reflex is performed using the video Head Impulse Test (vHIT). To date, the influence of different fixation distances on VOR gain using the vHIT has not been explored. We assessed the effect of target proximity on the horizontal VOR using the vHIT. Firstly, we assessed the VOR gain in 18 healthy subjects with 5 viewing target distances (150, 40, 30, 20, and 10 cm). The gain increased significantly as the viewing target distance decreased. A second experiment on 10 subjects was performed in darkness whilst the subjects were imagining targets at different distances. There were significant inverse relationships between gain and distance for both the real and the imaginary targets. There was a statistically significant difference between light and dark gains for the 20- and 40-cm distances, but not for the 150-cm distance. Theoretical VOR gains for different target distances were calculated and compared with those found in light and darkness. The increase in gain observed for near targets was lower than predicted by geometrical calculations, implying a physiological ceiling effect on the VOR. The VOR gain in the dark, as assessed with the vHIT, demonstrates an enhancement associated with a reduced target distance.

scholarly journals Effects of Device on Video Head Impulse Test (vHIT) Gain

2017 ◽  
Vol 28 (09) ◽  
pp. 778-785 ◽  
Author(s):  
Kristen L. Janky ◽  
Jessie N. Patterson ◽  
Neil T. Shepard ◽  
Megan L. A. Thomas ◽  
Julie A. Honaker
Keyword(s):  
Normal Control ◽  
Vestibular Function ◽  
Head Impulse Test ◽  
Video Head Impulse Test ◽  
Vestibular Loss ◽  
Directional Bias ◽  
Horizontal Canal ◽  
Head Impulse ◽  
Control Subjects ◽  
Bilateral Vestibular Loss

AbstractNumerous video head impulse test (vHIT) devices are available commercially; however, gain is not calculated uniformly. An evaluation of these devices/algorithms in healthy controls and patients with vestibular loss is necessary for comparing and synthesizing work that utilizes different devices and gain calculations.Using three commercially available vHIT devices/algorithms, the purpose of the present study was to compare: (1) horizontal canal vHIT gain among devices/algorithms in normal control subjects; (2) the effects of age on vHIT gain for each device/algorithm in normal control subjects; and (3) the clinical performance of horizontal canal vHIT gain between devices/algorithms for differentiating normal versus abnormal vestibular function.Prospective.Sixty-one normal control adult subjects (range 20–78) and eleven adults with unilateral or bilateral vestibular loss (range 32–79).vHIT was administered using three different devices/algorithms, randomized in order, for each subject on the same day: (1) Impulse (Otometrics, Schaumberg, IL; monocular eye recording, right eye only; using area under the curve gain), (2) EyeSeeCam (Interacoustics, Denmark; monocular eye recording, left eye only; using instantaneous gain), and (3) VisualEyes (MicroMedical, Chatham, IL, binocular eye recording; using position gain).There was a significant mean difference in vHIT gain among devices/algorithms for both the normal control and vestibular loss groups. vHIT gain was significantly larger in the ipsilateral direction of the eye used to measure gain; however, in spite of the significant mean differences in vHIT gain among devices/algorithms and the significant directional bias, classification of “normal” versus “abnormal” gain is consistent across all compared devices/algorithms, with the exception of instantaneous gain at 40 msec. There was not an effect of age on vHIT gain up to 78 years regardless of the device/algorithm.These findings support that vHIT gain is significantly different between devices/algorithms, suggesting that care should be taken when making direct comparisons of absolute gain values between devices/algorithms.

scholarly journals Comparison of two systems for the video head impulse test (vHIT) for the lateral semicircular canal: description of results from normal and pathological subjects

2021 ◽  
Vol 79 (7) ◽  
pp. 571-578
Author(s):  
Lilian Felipe
Keyword(s):  
Objective Assessment ◽  
Semicircular Canals ◽  
Small Sample ◽  
Head Impulse Test ◽  
Functional Evaluation ◽  
Video Head Impulse Test ◽  
Vestibular Disorder ◽  
Head Impulse ◽  
Two Systems ◽  
Head Impulses

ABSTRACT Background: The video head impulse test (vHIT) is a recent technique for functional evaluation of semicircular canals (SSCs). The vHIT examines eye movements at high frequencies of stimulation and provides an objective assessment of the functioning of the high-frequency domain of the vestibular system. Objective: To describe the results from vHIT performed using two systems. Methods: All subjects were evaluated through an audiological and otoneurological battery of tests and were diagnosed as normal or abnormal by an otorhinolaryngologist. The results from two systems: 1. ICS Impulse (Otometrics/Natus, Denmark) and 2. EyeSeeCam (InterAcoustics, Denmark) were recorded. The same operator delivered every impulse to every subject. The head impulses were performed while the operator was standing behind the subject, using both hands on the top of the subject’s head, well away from the goggles strap and forehead skin. Two calibrations were completed in each system, prior to beginning the test. Results: Test parameters were recorded through both systems for healthy subjects with no history or complaint of any vestibular disorder (N = 12; M/F = 5/7; age 35.1 ± 13.5 y) and for pathological subjects with a diagnosis of unilateral or bilateral vestibular disorder (N = 15; M/F = 7/8; age 53.4 ± 16.7 y). Conclusions: The vHIT is an important tool for otoneurological complementary evaluation. Both systems are reliable for vestibular disorders. The EyeSeeCam seems to reject fewer data and provides more information to include in diagnostics. Because of the small sample, there is a need for further in-depth comparison of both systems.

scholarly journals Reduced Purposeful Head Movements During Community Ambulation Following Unilateral Vestibular Loss

2018 ◽  
Vol 32 (4-5) ◽  
pp. 309-316 ◽  
Author(s):  
Serene Sulyn Paul ◽  
Leland E. Dibble ◽  
Raymond G. Walther ◽  
Clough Shelton ◽  
Richard Klaus Gurgel ◽  
...  
Keyword(s):  
Head Movement ◽  
Cross Sectional Study ◽  
Head Movements ◽  
Healthy Individuals ◽  
Cross Sectional ◽  
Vestibular Loss ◽  
Vestibular Hypofunction ◽  
Large Head ◽  
Community Ambulation ◽  
Measurement Units

Background. Individuals with unilateral vestibular hypofunction (UVH) alter their movement and reduce mobility to try to stabilize their gaze and avoid symptoms of dizziness and vertigo. Objective. To determine if individuals with UVH 6 weeks after surgery demonstrate altered head and trunk kinematics during community ambulation. Methods. A total of 15 vestibular schwannoma patients with documented postoperative unilateral vestibular loss and 9 healthy controls with symmetrical vestibulo-ocular reflexes participated in this cross-sectional study. Head kinematics (head turn frequency, amplitude, and velocity) and head-trunk coordination during community ambulation were obtained from inertial measurement units for all head movements and within specific amplitudes of head movement. Results. Individuals with UVH made smaller (mean 26° [SD = 3°] vs 32° [SD = 6°]), fewer (mean 133 [SD = 59] vs 221 [SD = 64]), and slower (mean 75°/s [SD = 8°/s] vs 103°/s [SD = 23°/s]) head turns than healthy individuals ( P < .05) but did not demonstrate significantly increased head-trunk coupling (mean 38% [SD = 18%] vs 31% [SD = 11%], P = .22). When small (≤45°) and large (>45°) head turns were considered separately, individuals with UVH demonstrated increased head-trunk coupling compared with healthy individuals for large head turns (mean 54% [SD = 23%] vs 33% [SD = 10%], P = .005). Conclusions. This study demonstrated that although walking at an adequate speed, individuals with UVH made fewer, smaller, and slower head movements symmetrically in both directions compared with healthy individuals and did not decouple their head movement relative to their trunk when required to make larger purposeful head turns during community ambulation.

scholarly journals Normal Saccadic Responses Using Video Head Impulse Test In Healthy Young Adults

2018 ◽  
Vol 17 (1) ◽  
Author(s):  
Nurul Amira Omar ◽  
Saiful Adli bin Jamaluddin
Keyword(s):  
Average Velocity ◽  
Infrared Camera ◽  
Head Movements ◽  
Head Impulse Test ◽  
Video Head Impulse Test ◽  
Head Impulse ◽  
Velocity Gain ◽  
Left Posterior ◽  
History Of

Introduction: Vertigo and dizziness are common symptoms reported in audiology and ENT clinics. One of the objective assessments includes the video head impulse test (vHIT) where gain & amp; velocity responses of eye movements relative to the head movements are recorded using an infrared camera. Materials and Methods: Thirty normal hearing subjects age between 18 to 25 years old participated in this study. Exclusion factors include those with the history of head or neck injury and vertigo. At least ten lateral, left anterior right posterior (LARP), and right anterior left posterior (RALP) responses were recorded for each participant by making small unpredictable head movements. Results: The average velocity gain for lateral responses at 40 ms, 60 ms and 80 ms were 1.05 ± 0.003, 1.03 ± 0.002 and 1.01 ± 0.003 respectively. The LARP and RALP average velocity regression were 1.01 ± 0.24 for left anterior and 1.05 ± 0.25 for right posterior, 1.08±0.31 for right anterior and 1.12 ± 0.30 for left posterior. One sample T-test was conducted to compare lateral responses to a previous study by Mossman et al. 2015. There were significant differences in velocity gain at 60 ms and 80 ms where, t (59) = 5.56, p < 0.01 and t (59) = 2.86, p < 0.01, respectively. Conclusion: This indicates the importance of establishing norms for clinics as various factors could affect the results such as techniques used and equipment differences. A follow-up study on subjects with vestibular disorders is required to validate this data as a normative reference.

The Effects of Cochlear Implantation on Vestibular Function

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P60-P60
Author(s):  
Thuy-Anh N. Melvin ◽  
Americo Migliaccio ◽  
John P Carey ◽  
Charles Coleman Della Santina
Keyword(s):  
Cochlear Implantation ◽  
Full Range ◽  
Vestibular Function ◽  
Head Movements ◽  
Vestibular Evoked Myogenic Potentials ◽  
Head Impulse Test ◽  
Head Impulse ◽  
Vestibular Hypofunction ◽  
Before And After ◽  
Vestibulo Ocular Reflex

Objective 1) Measure vestibular function before and after cochlear implantation (CI) using a battery of tests covering the full range of stimulus frequencies over which the normal angular vestibulo-ocular reflex (VOR) stabilizes gaze. Methods Semicircular canal (SCC) function was assayed using head impulse test during 3-dimensional scleral search coil eye movement recordings (HIT), dynamic visual acuity during rapid head movements (DVA), head-shake nystagmus (HSN), and caloric electronystagmography (ENG). Saccular function was determined using vestibular-evoked myogenic potentials (VEMP). Patient self-assessment via the dizziness handicap inventory (DHI) and clinical head impulse testing (cHIT) were also measured. Results One of 28 post-implanted ears (4%) suffered severe loss of vestibular function in all 3 SCCs. HSN revealed no change in 11 subjects. ENG revealed new hypofunction in 1 of 16 ears (6%). Passive DVA revealed no significant change for 16 implanted ears. VEMP revealed significant increase or disappearance in threshold in 5 of 16 ears (31%). DHI scores were variable and correlated poorly with objective tests. The cHIT performed by one otolaryngologist in 14 subjects exhibited 44% sensitivity and 94% specificity for detection of severe hypofunction confirmed via quantitative HIT. Conclusions CI carries a small but nontrivial risk of iatrogenic vestibular hypofunction in the implanted ear. For bilateral simultaneous-CI, the risk of bilateral vestibular hypofunction is ∼0.16%, comparable to the likelihood of meningitis. The cHIT was highly specific for vestibular hypofunction in this study, but likely depends heavily on the examiner's threshold for abnormal.

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