scholarly journals Finding a Balance: A Systematic Review of the Biomechanical Effects of Vestibular Prostheses on Stability in Humans

2020 ◽  
Vol 5 (2) ◽  
pp. 23
Author(s):  
Felix Haxby ◽  
Mohammad Akrami ◽  
Reza Zamani
Keyword(s):  
Vestibular System ◽  
Postural Sway ◽  
Vestibular Function ◽  
Vestibular Stimulation ◽  
Significant Heterogeneity ◽  
Vestibular Loss ◽  
Ocular Reflex ◽  
Gait Characteristics ◽  
Vestibulo Ocular Reflex ◽  
Meta Analyses

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.

Vestibulospinal Findings in Two Syndromes with Spontaneous Vertigo Attacks

1989 ◽  
Vol 98 (3) ◽  
pp. 191-195 ◽  
Author(s):  
Marcel E. Norré ◽  
Gabriel Forrez ◽  
Ann Beckers
Keyword(s):  
Postural Sway ◽  
The Other ◽  
Vestibular Loss ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Central Compensation ◽  
Comparison Of The Results ◽  
Stepping In Place ◽  
Central Adaptation ◽  
Normal Performance

The influence of vestibular dysfunction upon the vestibulospinal reflex (VSR) in two common peripheral syndromes was investigated by two types of posturographic examination: “static” posturography, recording and analyzing the postural sway in stance, and “kinetic” posturography, recording the stepping in place test. The influence of the dysfunction was examined outside the attacks, ie, between attacks and not during or immediately after an attack, in patients with Meniere's disease and in others with a sudden vestibular loss syndrome, “neuronitis.” However, in both syndromes the influence of the dysfunction was obvious only in some patients; this indicates that central adaptation intervened in the other patients. In this way, central compensation related to the VSR was assessed and compared with compensation for the vestibulo-ocular reflex assessed by the rotation tests. Discordance was shown in a number of cases, ie, a number of cases showed compensation for one reflex, but not for the other. Comparison of the results of both posturographic methods also showed discordance. Normal performance in the walking test could not always be correlated with normal performance in the standing test and vice versa.

Implications of Ewald's Second Law for the Evaluation of Vestibular Function

1979 ◽  
Vol 87 (4) ◽  
pp. 453-458 ◽  
Author(s):  
Young S. Kim ◽  
Clifford G. Y. Lau ◽  
Herman A. Jenkins ◽  
Vicente Honrubia
Keyword(s):  
Vestibular System ◽  
Semicircular Canal ◽  
Piecewise Linear ◽  
Vestibular Function ◽  
Second Law ◽  
Horizontal Semicircular Canal ◽  
Transfer Characteristics ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Ewald’S Second Law

The significance of Ewald's second law in the evaluation of the vestibulo-ocular reflex (VOR) was Investigated using the transfer characteristics of the vestibular and VOR systems in normal rabbits and rabbits in which one horizontal semicircular canal had been blocked. The transfer characteristics of the vestibular system were derived from the experimental results reported by Goldberg and Fernandez in 1971. A comparison was made of the properties of the bilateral and monolateral VOR systems with the predictions of a piecewise linear model of the vestibular system. The data received quantitatively collaborate the prediction of Ewald's second law as ft applies to the VOR responses.

scholarly journals Pre-habilitation Before Vestibular Schwannoma Surgery—Impact of Intratympanal Gentamicin Application on the Vestibulo-Ocular Reflex

2021 ◽  
Vol 12 ◽  
Author(s):  
Alexander A. Tarnutzer ◽  
Christopher J. Bockisch ◽  
Elena Buffone ◽  
Alexander M. Huber ◽  
Vincent G. Wettstein ◽  
...  
Keyword(s):  
Vestibular Schwannoma ◽  
Vestibular Function ◽  
Loss Of Function ◽  
Saccadic Amplitude ◽  
Vestibular Loss ◽  
Horizontal Canal ◽  
Ocular Reflex ◽  
Intratympanic Gentamicin ◽  
Vestibulo Ocular Reflex ◽  
Anterior Canal

Background: Patients with vestibular schwannoma that show residual peripheral-vestibular function before surgery may experience sudden and substantial vestibular loss of function after surgical resection. To alleviate the sudden loss of peripheral-vestibular function after vestibular-schwannoma (VS) resection, pre-surgical intratympanic gentamicin application was proposed.Objective: We hypothesized that this approach allows for a controlled reduction of peripheral-vestibular function before surgery but that resulting peripheral-vestibular deficits may be canal-specific with anterior-canal sparing as observed previously in systemic gentamicin application.Methods: Thirty-four patients (age-range = 27–70 y) with unilateral VS (size = 2–50 mm) were included in this retrospective single-center trial. The angular vestibulo-ocular reflex (aVOR) was quantified before and after (29.7 ± 18.7 d, mean ± 1SD) a single or two sequential intratympanic gentamicin applications by use of video-head-impulse testing. Both aVOR gains, cumulative saccadic amplitudes, and overall aVOR function were retrieved. Statistical analysis was done using a generalized linear model.Results: At baseline, loss of function of the horizontal (20/34) and posterior (21/34) canal was significantly (p < 0.001) more frequent than that of the anterior canal (5/34). After gentamicin application, loss of function of the horizontal (32/34) or posterior (31/34) canal remained significantly (p ≤ 0.003) more frequent than that of the anterior canal (18/34). For all ipsilesional canals, significant aVOR-gain reductions and cumulative-saccadic-amplitude increases were noted after gentamicin. For the horizontal canal, loss of function was significantly larger (increase in cumulative-saccadic-amplitude: 1.6 ± 2.0 vs. 0.8 ± 1.2, p = 0.007) or showed a trend to larger changes (decrease in aVOR-gain: 0.24 ± 0.22 vs. 0.13 ± 0.29, p = 0.069) than for the anterior canal.Conclusions: Intratympanic gentamicin application resulted in a substantial reduction in peripheral-vestibular function in all three ipsilesional canals. Relative sparing of anterior-canal function noted at baseline was preserved after gentamicin treatment. Thus, pre-surgical intratympanic gentamicin is a suitable preparatory procedure for reducing the drop in peripheral-vestibular function after VS-resection. The reasons for relative sparing of the anterior canal remain unclear.

Evidence a shared mechanism mediates ipsi- and contralesional compensatory saccades and gait after unilateral vestibular deafferentation

2020 ◽  
Vol 123 (4) ◽  
pp. 1486-1495 ◽  
Author(s):  
Andrew R. Wagner ◽  
Michael C. Schubert
Keyword(s):  
Gait Speed ◽  
Vestibular Function ◽  
Head Rotation ◽  
Common Mechanism ◽  
Walk Test ◽  
Vestibular Loss ◽  
Study Objective ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Unilateral Vestibular Deafferentation

The study objective was to understand how the contralesional labyrinth contributes to gaze and gait stability after unilateral vestibular deafferentation (UVD). Head impulse testing (vHIT) was completed in 37 individuals [22 women (59%); age 52.13 ± 11.59 yr, mean ± SD] with UVD from vestibular schwannoma resection. Compensatory saccades (CS) and vestibulo-ocular reflex (VOR) gain were analyzed for both ipsilesional and contralesional impulses. Gait speed (10-m walk test) and endurance (2-min walk test) were collected for 35 individuals. CS were recruited during contralesional head rotation regardless of VOR gain on either the ipsilesional [ρ = 0.21 (−0.14, 0.57); Spearman rank (95% confidence interval)] or contralesional side [ρ = −0.04 (−0.42, 0.35)]. Additionally, the latency of these CS (151.19 ± 52.41 ms) was similar to that of CS generated during ipsilesional rotation (165.65 ± 21.62 ms; P = 0.159). CS recruited during ipsilesional vHIT were of a higher velocity ( P < 0.001) and greater frequency ( P < 0.001) compared with contralesional CS. VOR gain asymmetry was significantly correlated with gait speed [ρ = −0.37 (−0.73, −0.01)], yet individual VOR gain was not correlated [ipsilesional: ρ = 0.17 (−0.20, 0.55); contralesional: ρ = −0.18 (−0.52, 0.15)]. Our data reveal CS are recruited at similar latencies without correlation to VOR gain or direction of head rotation, and that the central integration of ipsilesional and contralesional vestibular afference correlates with gait. Together, our data suggest the brain considers vestibular afference from both sides when generating related behavioral output after UVD. NEW & NOTEWORTHY After unilateral vestibular deafferentation, compensatory saccades (CS) have similar latencies regardless of the direction of head rotation, and those CS generated during contralesional head rotation are unrelated to extent of vestibular loss. Additionally, the extent of asymmetry in residual vestibular function, not the extent of vestibular loss, correlates with gait speed. Our data suggest a common mechanism is responsible for the generation of CS and restoration of gait speed in vestibular compensation.

scholarly journals How do red-eyed treefrog embryos sense motion in predator attacks? Assessing the role of vestibular mechanoreception

2019 ◽  
Author(s):  
Julie Jung ◽  
Su J. Kim ◽  
Sonia M. Pérez Arias ◽  
James G. McDaniel ◽  
Karen M. Warkentin
Keyword(s):  
Vestibular System ◽  
Vestibular Function ◽  
Developmental Period ◽  
Limiting Factor ◽  
Environmental Cues ◽  
Physical Disturbance ◽  
Agalychnis Callidryas ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

ABSTRACTThe widespread ability to alter hatching timing in response to environmental cues can serve as a defense against threats to eggs. Arboreal embryos of red-eyed treefrogs, Agalychnis callidryas, hatch up to 30% prematurely to escape predation. This escape-hatching response is cued by physical disturbance of eggs during attacks, including vibrations or motion, and thus depends critically on mechanosensory ability. Predator-induced hatching appears later in development than flooding-induced, hypoxia-cued hatching; thus, its onset is not constrained by the development of hatching ability. It may, instead, reflect the development of mechanosensor function. We hypothesize that vestibular mechanoreception mediates escape-hatching in snake attacks, and that the developmental period when hatching-competent embryos fail to flee from snakes reflects a sensory constraint. We assessed the ontogenetic congruence of escape-hatching responses and an indicator of vestibular function, the vestibulo-ocular reflex (VOR), in three ways. First, we measured VOR in two developmental series of embryos 3–7 days old to compare with the published ontogeny of escape success in attacks. Second, during the period of greatest variation in VOR and escape success, we compared hatching responses and VOR across sibships. Finally, in developmental series, we compared the response of individual embryos to a simulated attack cue with their VOR. The onset of VOR and hatching responses were largely concurrent at all three scales. Moreover, latency to hatch in simulated attacks decreased with increasing VOR. These results are consistent with a key role of the vestibular system in the escape-hatching response of A. callidryas embryos to attacks.Red-eyed treefrogs’ hatching responses to predator attacks, vibration playbacks, and egg-jiggling appear when vestibular function develops. Ear development may be a key limiting factor in the onset of mechanosensory-cued hatching.

The effects of stochastic monopolar galvanic vestibular stimulation on human postural sway

2003 ◽  
Vol 12 (2-3) ◽  
pp. 77-85
Author(s):  
Anthony P. Scinicariello ◽  
J. Timothy Inglis ◽  
J.J. Collins
Keyword(s):  
Vestibular System ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
Lower Sensitivity ◽  
Input Stimulus ◽  
Vestibular Perception ◽  
Afferent Nerve Endings ◽  
Young Subjects

Galvanic vestibular stimulation (GVS) is a technique in which small currents are delivered transcutaneously to the afferent nerve endings of the vestibular system through electrodes placed over the mastoid bones. The applied current alters the firing rates of the peripheral vestibular afferents, causing a shift in a standing subject's vestibular perception and a corresponding postural sway. Previously, we showed that in subjects who are facing forward, stochastic bipolar binaural GVS leads to coherent stochastic mediolateral postural sway. The goal of this pilot study was to extend that work and to test the hypothesis that in subjects who are facing forward, stochastic monopolar binaural GVS leads to coherent stochastic anteroposterior postural sway. Stochastic monopolar binaural GVS was applied to ten healthy young subjects. Twenty-four trials, each containing a different galvanic input stimulus from among eight different frequency ranges, were conducted on each subject. Postural sway was evaluated through analysis of the center-of-pressure (COP) displacements under each subject's feet. Spectral analysis was performed on the galvanic stimuli and the COP displacement time series to calculate the coherence spectra. Significant coherence was found between the galvanic input signal and the anteroposterior COP displacement in some of the trials (i.e., at least one) in nine of the ten subjects. In general, the coherence values were highest for the mid-range frequencies that were tested, and lowest for the low- and high-range frequencies. However, the coherence values we obtained were lower than those we previously reported for stochastic bipolar binaural GVS and mediolateral sway. These differences may be due to fundamental characteristics of the vestibular system such as lower sensitivity to symmetric changes in afferent firing dynamics, and/or differences between the biomechanics of anteroposterior and mediolateral sway.

scholarly journals A review on screening tests for vestibular disorders

2019 ◽  
Vol 122 (1) ◽  
pp. 81-92 ◽  
Author(s):  
Helen S. Cohen
Keyword(s):  
Vestibular System ◽  
Epidemiological Studies ◽  
Screening Tests ◽  
Clinical Test ◽  
Clinical Use ◽  
Ocular Reflex ◽  
System A ◽  
Screening Battery ◽  
Vestibulo Ocular Reflex ◽  
Romberg Test

Although many studies have reported on tests of the vestibular system a valid and reliable, evidence-based screening battery for easy clinical use remains elusive. Many screening tests attempt to assess the vestibulo-ocular reflex. Therefore, head shaking, the Dix-Hallpike maneuver, the supine roll test, and head impulse tests are discussed. Other tests address the spatial orientation functions of the vestibular system, such as the Bucket Test and the Fukuda Stepping test. Still, other tests are based on the known correlates with balance skills, both static and dynamic, such as tandem walking and the modern variation of the Romberg test, the modified Clinical Test of Sensory Interaction and Balance. This review provides a critical overview of the literature on some of these tests and their value for clinical use and in epidemiological studies.

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

2007 ◽  
Vol 18 (03) ◽  
pp. 236-244 ◽  
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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