An Assay for Systematically Quantifying the Vestibulo-Ocular Reflex to Assess Vestibular Function in Zebrafish Larvae

The vestibular system is located in the inner ear and is responsible for maintaining balance in humans. Bilateral vestibular dysfunction (BVD) is a disorder that adversely affects vestibular function. This results in symptoms such as postural imbalance and vertigo, increasing the incidence of falls and worsening quality of life. Current therapeutic options are often ineffective, with a focus on symptom management. Artificial stimulation of the vestibular system, via a vestibular prosthesis, is a technique being explored to restore vestibular function. This review systematically searched for literature that reported the effect of artificial vestibular stimulation on human behaviours related to balance, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) technique. A total of 21 papers matched the inclusion criteria of the literature search conducted using the PubMed and Web of Science databases (February 2019). The populations for these studies included both healthy adults and patients with BVD. In every paper, artificial vestibular stimulation caused an improvement in certain behaviours related to balance, although the extent of the effect varied greatly. Various behaviours were measured such as the vestibulo-ocular reflex, postural sway and certain gait characteristics. Two classes of prosthesis were evaluated and both showed a significant improvement in at least one aspect of balance-related behaviour in every paper included. No adverse effects were reported for prostheses using noisy galvanic vestibular stimulation, however, prosthetic implantation sometimes caused hearing or vestibular loss. Significant heterogeneity in methodology, study population and disease aetiology were observed. The present study confirms the feasibility of vestibular implants in humans for restoring balance in controlled conditions, but more research needs to be conducted to determine their effects on balance in non-clinical settings.

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Comparison of Horizontal and Vertical Dynamic Visual Acuity in Patients with Vestibular Dysfunction and Nonvestibular Dizziness

Journal of the American Academy of Audiology ◽

10.3766/jaaa.18.3.5 ◽

2007 ◽

Vol 18 (03) ◽

pp. 236-244 ◽

Cited By ~ 4

Author(s):

Richard A. Roberts ◽

Richard E. Gans

Keyword(s):

Visual Acuity ◽

Head Movement ◽

Vestibular Function ◽

Vestibular Dysfunction ◽

Common Symptom ◽

Dynamic Visual Acuity ◽

Blurred Vision ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Horizontal Head

Blurred vision with head movement is a common symptom reported by patients with vestibular dysfunction affecting the vestibulo-ocular reflex (VOR). Impaired VOR can be measured by comparing visual acuity in which there is no head movement to visual acuity obtained with head movement. A previous study demonstrated that dynamic visual acuity (DVA) testing using vertical head movement revealed deficits in impaired VOR. There is evidence that horizontal head movement is more sensitive to impaired VOR. The objective of this investigation was to compare horizontal and vertical DVA in participants with normal vestibular function (NVF), impaired vestibular function (IVF), and participants with nonvestibular dizziness (NVD). Participants performed the visual acuity task in a baseline condition with no movement and also in two dynamic conditions, horizontal head movement and vertical head movement. Horizontal DVA was twice as sensitive to impaired VOR than vertical DVA. Results suggest that horizontal volitional head movement should be incorporated into tasks measuring functional deficits of impaired VOR. Una visión borrosa con los movimientos de la cabeza es un síntoma común reportado por los pacientes con una disfunción vestibular que afecta el reflejo vestíbulo-ocular (VOR). La alteración en el VOR puede ser medida comparando la aguda visual no acompañada de movimientos de la cabeza, con la aguda visual obtenida con movimientos cefálicos. Un estudio previo demostró que la prueba de aguda visual dinámica (DVA) usando movimiento vertical de la cabeza revelaba deficiencias relacionados con un VOR alterado. Existe evidencia que el movimiento cefálico horizontal es más sensible a un VOR alterado. El objetivo de esta investigación fue comparar el DVA horizontal y vertical en participantes con funcional vestibular normal (NVF), con función vestibular alterada (IVF) y en sujetos con mareo no vestibular (NVD). Los participantes realizaron sus tareas de agudeza visual en una condición basal, sin movimiento, y también en dos condiciones dinámicas, con movimientos de cabeza horizontales y verticales. El DVA horizontal fue dos veces más sensible a un VOR alterado que el DVA vertical. Los resultados sugieren que los movimientos volitivos horizontales de la cabeza deben incorporarse en las tareas que midan deficiencias funcionales con un VOR alterado.

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Relation Between Perception of Vertical Axis Rotation and Vestibulo-Ocular Reflex Symmetry

Journal of Vestibular Research ◽

10.3233/ves-1992-2105 ◽

1992 ◽

Vol 2 (1) ◽

pp. 59-69

Author(s):

Robert J. Peterka ◽

Martha S. Benolken

Keyword(s):

Measurement Errors ◽

Rotational Velocity ◽

Vestibular Function ◽

Vertical Axis ◽

Perceptual Bias ◽

Common Source ◽

Ocular Reflex ◽

Small Constant ◽

Vestibulo Ocular Reflex ◽

Axis Rotation

Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in a subject’s perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function that could be of either central or peripheral origin. Deviations from perfect vestibulo-ocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. We looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflexive and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests in the same subjects of both perceptual bias and VOR symmetry were well correlated.

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Recovery of vestibulo-ocular reflex-function in subjects with an acute unilateral peripheral vestibular deficit

Journal of Vestibular Research ◽

10.3233/ves-1999-9208 ◽

1999 ◽

Vol 9 (2) ◽

pp. 135-144 ◽

Cited By ~ 1

Author(s):

J.H.J. Allum ◽

T. Ledin

Keyword(s):

Low Frequency ◽

Vestibular Function ◽

Vertical Axis ◽

Whole Body ◽

Horizontal Semicircular Canal ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Central Compensation ◽

Head Rotations ◽

Vestibular Deficit

The centrally controlled compensation for a reduced horizontal vestibulo-ocular reflex (VOR) gain caused by a unilateral afferent deficit is usually studied following a selective surgical procedure which completely lesions the vestibular nerve or blocks the horizontal semicircular canal. The more common, unilateral, vestibular deficit encountered clinically, is a partial loss of peripheral vestibular function, following which peripheral recovery and/or central compensation may occur. We investigated changes of the VOR gain in response to a sudden, idiopathic, unilateral vestibular deficit in 64 subjects by examining the responses to low-frequency, whole-body, rotations about an earth vertical axis with different accelerations (5, 20 and 40 deg / sec 2 ) during in- and out-patient visits separated by 4 months in an attempt to identify changes brought about by peripheral recovery and by central compensation processes. Peripheral function was assumed to be measured by the response to caloric irrigation. It improved some 30% between the two visits. VOR responses for rotations towards the deficit side also improved between the two visits. Most improvement occurred for 20 deg / sec 2 accelerations. However, the correlation coefficient between rotation and caloric responses was always less than 0.6. Unlike caloric responses which improved over time, responses for rotations to the intact side did not change between the visits. For this reason, the majority of observed VOR rotation responses were nearly symmetrical at the time of the second visit, despite being below normal levels. These findings suggest that both peripheral recovery and central compensation processes help restore symmetrical VOR function for head rotations after a partial unilateral vestibular deficit. However the improvement of VOR response symmetry, particularly to slow ( < 40 deg / sec 2 ) accelerations, is largely independent of the recovery of peripheral sensitivity.

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Effect of aging on the otolith-ocular reflex

Journal of Vestibular Research ◽

10.3233/ves-2001-11204 ◽

2001 ◽

Vol 11 (2) ◽

pp. 91-103

Author(s):

Joseph M. Furman ◽

Mark S. Redfern

Keyword(s):

Semicircular Canal ◽

Head Tilt ◽

Vestibular Function ◽

Vertical Axis ◽

Ocular Reflex ◽

Age Related ◽

Vestibulo Ocular Reflex ◽

Older Subjects ◽

Axis Rotation ◽

Reflex Time

We assessed the influence of age on the otolith-ocular reflex and semicircular canal-otolith interaction. Healthy young (n=30) and healthy older (n=60) subjects were rotated about an earth vertical axis, and about a 30 degree off-vertical axis. Eye movements during and following rotation were recorded using electro-oculography. Results indicated that there were statistically significant changes in the otolith-ocular reflex and semicircular canal-otolith interaction as a function of age. The modulation component during off-vertical axis rotation (OVAR) was greater in the older group compard to the young adults, whereas the bias component was smaller with advanced age. The foreshortening of the vestibulo-ocular reflex time constant induced by post-rotatory head tilt following cessation of rotation was less prominent in the older group. There were no consistent changes in the semicircular canal-ocular reflex. Overall, response parameters showed more variability in the older subjects. We conclude that age related changes in the otolith-ocular reflex and semicircular canal-otolith interaction are a result primarily of a degradation of central vestibular processing of otolith signals rather than a decline of peripheral vestibular function.

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On the Search for Markers of Poor Vestibular Compensation

Otolaryngology ◽

10.1177/019459988910100511 ◽

1989 ◽

Vol 101 (5) ◽

pp. 572-577 ◽

Cited By ~ 6

Author(s):

Brian W. Blakley ◽

Hugh O. Barber ◽

R. David Tomlinson ◽

Susan Stoyanoff ◽

Mabel Mai

Keyword(s):

Vestibular Function ◽

Vestibular Compensation ◽

Clinical Tool ◽

Vestibular Function Tests ◽

Control Subjects ◽

Ocular Reflex ◽

Function Tests ◽

Vestibulo Ocular Reflex ◽

Pursuit Gain

The effectiveness of pursuit gain, cancellation of the vestibulo-ocular reflex, and a clinical oscillopsia test were assessed as vestibular function tests and tests that may allow prediction of which patients would compensate poorly after vestibular surgery. Cancellation of the vestibulo-ocular reflex in 17 patients and 17 control subjects was compared. Pursuit gain for 17 patients was determined for three frequencies at peak velocities of 25 and 50 degrees/sec. The oscillopsia test was administered to seven patients during at least the first 6 postoperative months. We are unable to state that any of these parameters were effective “markers” of impaired compensation, but the oscillopsia test appears to be a useful clinical tool for vestibular examination.

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Clinical-pathologic correlation in a patient with selective loss of hair cells in the vestibular endorgans

Neurology ◽

10.1212/wnl.49.5.1377 ◽

1997 ◽

Vol 49 (5) ◽

pp. 1377-1382 ◽

Cited By ~ 10

Author(s):

R. W. Baloh ◽

I. Lopez ◽

K. Beykirch ◽

A. Ishiyama ◽

V. Honrubia

Keyword(s):

Time Constant ◽

Hair Cells ◽

Vestibular Function ◽

Cochlear Hair Cells ◽

Vestibular Hair Cells ◽

Selective Loss ◽

Ocular Reflex ◽

Hearing Function ◽

Vestibulo Ocular Reflex ◽

Vestibular Endorgans

We found a selective loss of vestibular hair cells in a patient followed for more than 10 years with imbalance and oscillopsia due to idiopathic progressive loss of vestibular function. Hearing function and cochlear hair cells were normal. The vestibulo-ocular reflex (VOR) gain at high frequencies was relatively maintained despite marked shortening of the dominant VOR time constant (to less than 500 ms). Ultrastructural examination of remaining hair cells showed mitochondrial abnormalities. The ultrashort VOR time constant probably resulted from changes in firing patterns of the primary afferent nerves due to loss of hair cells and impaired energy metabolism in remaining hair cells.

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Study of Pursuit and Vestibulo-Ocular Cancellation

Otolaryngology ◽

10.1177/019459988609500512 ◽

1986 ◽

Vol 95 (5) ◽

pp. 589-591 ◽

Cited By ~ 8

Author(s):

M. Mai ◽

V.S. Dayal ◽

R.D. Tomlinson ◽

J. Farkashidy

Keyword(s):

Single Dose ◽

High Frequency ◽

Vestibular Function ◽

Sedative Effect ◽

Drug Intake ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Analysis Of Results ◽

Time Courses

This present study, a follow-up of our earlier investigation, further examines the time courses of recovery of oculomotor and vestibular function while patients are under the sedative effect of a single dose of secobarbital (Seconal). The assessment included tests for saccade and smooth pursuit, and the vestibulo-ocular reflex and its cancellation, as evaluated by sinusoidal and pseudorandom rotation in a high-frequency hydraulic chair (up to 5 Hz). Analysis of results showed that the vestibulo-ocular reflex (VOR) gain, depressed soon after drug intake, recovered substantially after a few hours. Changes in VOR gain were more pronounced with higher frequencies of rotation at 2 and 3 Hz, and greater with pseudorandom than sinusoidal stimulation. Under barbiturate influence, pursuit and VOR cancellation followed distinctly different time courses of recovery. This dissociation between VOR cancellation and pursuit supports the theory that these two systems are subserved by different mechanisms. Saccadic hypermetria was also observed after drug intake.

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Usefulness of manually rotated vestibulo-ocular reflex testing estimated from the viewpoint of peripheral vestibular function

Equilibrium Research ◽

10.3757/jser.72.182 ◽

2013 ◽

Vol 72 (3) ◽

pp. 182-191

Author(s):

Makoto Miura ◽

Chiaki Suzuki ◽

Hiroki Ikeda

Keyword(s):

Vestibular Function ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Reflex Testing

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Evaluation of betahistine for the prevention of seasickness: Effect on vestibular function, psychomotor performance and efficacy at sea

Journal of Vestibular Research ◽

10.3233/ves-2003-132-305 ◽

2003 ◽

Vol 13 (2-3) ◽

pp. 103-111 ◽

Cited By ~ 2

Author(s):

Carlos R. Gordon ◽

Ilana Doweck ◽

Zohar Nachum ◽

Adi Gonen ◽

Orna Spitzer ◽

...

Keyword(s):

Side Effects ◽

Psychomotor Performance ◽

Vestibular Function ◽

Placebo Treatment ◽

Crossover Design ◽

Performance Tests ◽

Double Blind ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Sinusoidal Harmonic Acceleration

Betahistine was evaluated for the prevention of seasickness in a laboratory and sea study. The effect of 48 mg betahistine on the vestibulo-ocular reflex (VOR) and on psychomotor performance was evaluated in twelve young healthy subjects in a double-blind, placebo controlled, randomized, crossover design. The vestibulo-ocular reflex was evaluated by the Sinusoidal Harmonic Acceleration (SHA) test at frequencies of 0.01, 0.02, 0.04, 0.08 and 0.16 Hz. Psychomotor performance was assessed by both computerized and paper and pencil test batteries. No significant differences in VOR gain or phase were found between betahistine and placebo treatment for any of the frequencies tested. No significant differences were found between treatments for any of the psychomotor performance tests or other possible side effects. The effect of 48 mg betahistine on seasickness severity was evaluated in 83 subjects during a voyage in rough seas. Betahistine had a borderline non-statistically significant effect on the prevention of seasickness in comparison with placebo (p = 0.053), with no notable side effects. Although our results are insufficient to recommend betahistine as an anti-seasickness drug, further studies are required to determine its possible effectiveness in less provocative motion sickness situations.

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