Pathways for the vestibulo-ocular reflex excitation arising from semicircular canals of rabbits

Abstract Introduction Auditory neuropathy spectrum disorder (ANSD) features the presence of otoacoustic emissions, poor speech identification score and absent auditory brainstem response. Objective The present study was designed to evaluate the functioning of all six semicircular canals in individuals with ANSD and to compare it with those of normal-hearing individuals. Methods A total of 50 individuals participated in the present study, in which Group I comprised 25 normal-hearing individuals, and Group II comprised 25 individuals with ANSD. All of the participants underwent case history, pure tone audiometry, immittance, otoacoustic emissions, auditory evoked response and video head impulse test (vHIT). Results The independent sample t-test revealed significantly lower vestibulo-ocular reflex gain values in individuals with ANSD. A presence of 100% corrective refixation saccades was observed in the same group. The Pearson correlation test revealed no significant correlation between vestibulo-ocular reflex (VOR) gain with duration of hearing loss and pure tone thresholds for any of the three orthogonal planes. The chi-squared test revealed no association between the VOR gain values and the presence or absence of saccades in any of the semicircular canals (p > 0.05). Conclusion Huge percentages of individuals with ANSD have been found to have associated vestibular dysfunction as well. Therefore, the vHIT can be used as one of the important tests of the vestibular test battery to evaluate all six semicircular canals in individuals with ANSD.

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Vestibulo-ocular reflex gain and compensatory saccades in three semicircular canals by video head impulse test

Auditory and Vestibular Research ◽

10.18502/avr.v28i1.415 ◽

2019 ◽

Author(s):

Homa Zarrinkoob ◽

Hadi Behzad ◽

Seyed Mehdi Tabatabaee

Keyword(s):

High Velocity ◽

Semicircular Canals ◽

Head Impulse Test ◽

Video Head Impulse Test ◽

Low Velocity ◽

Head Impulse ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Reflex Gain ◽

The Right

Background and Aim: One of the tools for assessing the vestibulo-ocular reflex (VOR) is using video head impulse test (vHIT). In this test by placing the head at different angles and shaking the head, three semicircular canals of the vestibular system in each ear can be examined separately. The purpose of this study was to investigate the relationship between the low and high velocities of the vHIT test with VOR and its compensatory saccades. Methods: The vHIT test was performed by an examiner in 49 normal individuals aged 23–39 at low and high velocities. All participants had normal hearing, visual, and vestibular systems. Results: Mean gains in the horizontal, anterior and posterior semicircular canals in the right ear respectively were 0.92, 1 and 0.90 and in the left ear 0.93, 0.99 and 0.95 for low velocity and 0.78, 0.92 and 0.79 in the right ear and 0.80, 0.85 and 0.86 in the left ear for high velocity. Also, the number of compensatory saccade at high velocity was higher than those at the low velocity and the latency of compensatory saccade was lower at the higher velocity. Conclusion: In the vHIT test, VOR gain decreases at high velocity that is statistically significant. Also, compensatory saccades are more likely to occur at high velocity with smaller delay. Therefore, high-velocity vHIT test is not recommended for the purpose of examining the VOR gain and compensatory saccade.

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Asymmetry of Vestibulo-Ocular Reflex in the Cat

Otolaryngology ◽

10.1177/019459988509300505 ◽

1985 ◽

Vol 93 (5) ◽

pp. 597-600 ◽

Cited By ~ 4

Author(s):

John H. Anderson ◽

Stephen L. Liston

Keyword(s):

Eye Movements ◽

Semicircular Canals ◽

Whole Body ◽

Slow Phase ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Vertical Semicircular Canals

Vertical eye movements were recorded in alert, restrained cats that were subjected to whole-body rotations which stimulated the vertical semicircular canals. The results showed a significant asymmetry between the upward and downward slow-phase eye movements, which suggests differences in the CNS processing of vertical canal inputs vis-à-vis the vestibulo-ocular reflex.

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Ictal downbeat nystagmus in Ménière disease

Neurology ◽

10.1212/wnl.0000000000010653 ◽

2020 ◽

Vol 95 (17) ◽

pp. e2409-e2417

Author(s):

Sun-Uk Lee ◽

Hyo-Jung Kim ◽

Jeong-Yoon Choi ◽

Ji-Soo Kim

Keyword(s):

Semicircular Canals ◽

Vestibular Evoked Myogenic Potentials ◽

Slow Phase ◽

Downbeat Nystagmus ◽

Meniere Disease ◽

Head Impulse ◽

Slow Phase Velocity ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Menière Disease

ObjectiveTo determine the mechanism of ictal downbeat nystagmus in Ménière disease (MD), we compared the head impulse gain of the vestibulo-ocular reflex (VOR) for each semicircular canal between patients with (n = 7) and without (n = 70) downbeat nystagmus during attacks of MD.MethodsWe retrospectively analyzed the results of video-oculography, video head-impulse tests, and cervical vestibular-evoked myogenic potentials (VEMPs) in 77 patients with definite MD who were evaluated during an attack.ResultsPure or predominant downbeat nystagmus was observed in 7 patients (9%) with unilateral MD during the attacks. All 7 patients showed spontaneous downbeat nystagmus without visual fixation with a slow phase velocity ranging from 1.5 to 11.2°/s (median 5.4, interquartile range 3.7–8.5). All showed a transient decrease of the head impulse VOR gains for the posterior canals (PCs) in both ears (n = 4) or in the affected ear (n = 3). Cervical VEMPs were decreased in the affected (n = 2) or both ears (n = 2) when evaluated during the attacks. Downbeat nystagmus disappeared along with normalization of the VOR gains for PCs after the attacks in all patients. During the attacks, the head impulse VOR gains for the PC on the affected side were lower in the patients with ictal downbeat nystagmus than in those without (Mann-Whitney U test, p < 0.001), while the gains for other semicircular canals did not differ between the groups.ConclusionDownbeat nystagmus may be observed during attacks of MD due to an asymmetry in the vertical VOR or saccular dysfunction. MD should be considered in recurrent audiovestibulopathy and ictal downbeat nystagmus.

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Optimizing the Sensitivity of the Head Thrust Test for Identifying Vestibular Hypofunction

Physical Therapy ◽

10.1093/ptj/84.2.151 ◽

2004 ◽

Vol 84 (2) ◽

pp. 151-158 ◽

Cited By ~ 67

Author(s):

Michael C Schubert ◽

Ronald J Tusa ◽

Lawrence E Grine ◽

Susan J Herdman

Keyword(s):

Health Information ◽

Sensitivity And Specificity ◽

Semicircular Canal ◽

Medical Records ◽

Semicircular Canals ◽

Test Results ◽

Lateral Semicircular Canal ◽

Ocular Reflex ◽

Vestibular Hypofunction ◽

Vestibulo Ocular Reflex

Abstract Background and Purpose. The head thrust test (HTT) is used to assess the vestibulo-ocular reflex. Sensitivity and specificity for diagnosing unilateral vestibular hypofunction (UVH) in patients following vestibular ablation is excellent (100%), although sensitivity is lower (35%–39%) for patients with nonsurgically induced UVH. The variability of the test results may be from moving the subject's head outside the plane of the lateral semicircular canals as well as using a head thrust of predictable timing and direction. The purpose of this study was to examine sensitivity and specificity of the horizontal HTT in identifying patients with UVH and bilateral vestibular hypofunction (BVH) when the head was flexed 30 degrees in attempt to induce acceleration primarily in the lateral semicircular canal and the head was moved unpredictably. Subjects. The medical records of 176 people with and without vestibular dysfunction (n=79 with UVH, n=32 with BVH, and n=65 with nonvestibular dizziness) were studied. Methods. Data were retrospectively tabulated from a de-identified database (ie, with health information stripped of all identifiers). Results. Sensitivity of the HTT for identifying vestibular hypofunction was 71% for UVH and 84% for BVH. Specificity was 82%. Discussion and Conclusion. Ensuring the head is pitched 30 degrees down and thrust with an unpredictable timing and direction appears to improve sensitivity of the HTT.

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Evaluation of Interexaminer Variability in Video Head Impulse Test Results

Journal of the American Academy of Audiology ◽

10.1055/s-0040-1717124 ◽

2020 ◽

Vol 31 (08) ◽

pp. 613-619

Author(s):

Başak Mutlu ◽

Sıdıka Cesur ◽

Merve Torun Topçu ◽

Cennet Reyyan Geçici ◽

Öyküm Esra Aşkın ◽

...

Keyword(s):

Repeated Measures ◽

Semicircular Canals ◽

Head Impulse Test ◽

Video Head Impulse Test ◽

Head Impulse ◽

Lateral Canal ◽

Ocular Reflex ◽

Left Posterior ◽

Vestibulo Ocular Reflex ◽

The Right

Abstract Objective The video head impulse test (vHIT) is a diagnostic tool to assess the function of the semicircular canals and branches of the vestibular nerve. The aim of this study was to analyze the interexaminer variability of vHIT results in healthy subjects. Materials and Methods A total of 21 healthy participants were included in the study. vHIT responses were collected by four clinicians. Variability of the vHIT results between examiners was analyzed statistically. Results The vestibulo-ocular reflex (VOR) velocity regression values were from 0.99 to 1.09 degrees per second for the lateral canals. For the vertical canals, VOR velocity regression values were from 0.87 to 1.21 degrees per second. According to repeated measures analysis of variance, the normality assumptions for the velocity regression of the left lateral canal (p = 0.002) and the right anterior canal (p < 0.01) were met and the differences were statistically significant. The normality assumptions were not met for 40, 60, and 80 ms median gain of the right lateral canal (p = 0.016, p = 0.038, and p = 0.001, respectively); 40 and 60 ms median gain of the left lateral canal (p < 0.001 and p = 0.008, respectively); and the velocity regression of the left posterior canal (p < 0.00). These differences were found to be statistically significant by using the Friedman test. Conclusion The interexaminer differences of the VOR gain values for the vHIT were statistically significant. Serial vHIT testing should be performed by the same examiner to reduce the effects of interexaminer variability.

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Semicircular Canal Structure during Postnatal Development in Cat and Guinea Pig

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348948209100214 ◽

1982 ◽

Vol 91 (2) ◽

pp. 185-192 ◽

Cited By ~ 4

Author(s):

I. S. Curthoys ◽

R. H. I. Blanks ◽

C. H. Markham

Keyword(s):

Postnatal Development ◽

Semicircular Canal ◽

Receptor Cell ◽

Semicircular Canals ◽

Postnatal Growth ◽

Related Function ◽

Ocular Reflex ◽

Skull Growth ◽

Vestibulo Ocular Reflex ◽

The Stability

The gain of the vestibulo-ocular reflex in the cat continues to increase for some time after birth. The reason for this increase is not presently known and one possibility is that it occurs because the cat semicircular canals increase in size. The present study examined this possibility by measuring the radii of curvature (R) of individual semicircular canals and the angular relationships of the semicircular canal planes within a labyrinth in cats and guinea pigs during postnatal growth. It was found that the labyrinths do move apart substantially during postnatal development in both species, but neither the planar relations nor the radii of curvature change significantly during postnatal development. The stability of semicircular canal structure during postnatal skull growth indicates that postnatal developmental changes in canal-related function, such as increased gain in the vestibulo-ocular reflex, in these species are probably due to receptor cell or neural maturational factors.

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