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Büki B, Migliaccio AA. The vergence-mediated gain increase: Physiology and clinical relevance. J Vestib Res 2023; 33:173-186. [PMID: 37005906 DOI: 10.3233/ves-220133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
BACKGROUND During near-viewing, the vestibulo-ocular reflex (VOR) response/gain increases to compensate for the relatively larger translation of the eyes with respect to the target. OBJECTIVE To review vergence-mediated gain increase (VMGI) testing methods stimuli and responses (latency and amplitude), peripheral/central pathways and clinical relevance. METHODS The authors discuss publications listed in PUBMED since 1980 in the light of their own studies. RESULTS The VMGI can be measured during rotational, linear and combined head accelerations. It has short-latency, non-compensatory amplitude, and relies on irregularly discharging peripheral afferents and their pathways. It is driven by a combination of perception, visual-context and internal modelling. CONCLUSIONS Currently, there are technical barriers that hinder VMGI measurement in the clinic. However, the VMGI may have diagnostic value, especially with regards to measuring otolith function. The VMGI also may have potential value in rehabilitation by providing insight about a patient's lesion and how to best tailor a rehabilitation program for them, that potentially includes VOR adaptation training during near-viewing.
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Affiliation(s)
- Bela Büki
- Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Mitterweg, Austria
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Randwick, NSW, Australia
- Graduate School of Biomedical Engineering, University of NSW, Sydney, NSW, Australia
- Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, NSW, Australia
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Büki B, Tamás LT, Todd CJ, Schubert MC, Migliaccio AA. Absence of a vergence-mediated vestibulo-ocular reflex gain increase does not preclude adaptation. J Vestib Res 2021; 31:109-117. [PMID: 33427708 DOI: 10.3233/ves-201560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The gain (eye-velocity/head-velocity) of the angular vestibuloocular reflex (aVOR) during head impulses can be increased while viewing near-targets and when exposed to unilateral, incremental retinal image velocity error signals. It is not clear however, whether the tonic or phasic vestibular pathways mediate these gain increases. OBJECTIVE Determine whether a shared pathway is responsible for gain enhancement between vergence and adaptation of aVOR gain in patients with unilateral vestibular hypofunction (UVH). MATERIAL AND METHODS 20 patients with UVH were examined for change in aVOR gain during a vergence task and after 15-minutes of ipsilesional incremental VOR adaptation (uIVA) using StableEyes (a device that controls a laser target as a function of head velocity) during horizontal passive head impulses. A 5 % aVOR gain increase was defined as the threshold for significant change. RESULTS 11/20 patients had >5% vergence-mediated gain increase during ipsi-lesional impulses. For uIVA, 10/20 patients had >5% ipsi-lesional gain increase. There was no correlation between the vergence-mediated gain increase and gain increase after uIVA training. CONCLUSION Vergence-enhanced and uIVA training gain increases are mediated by separate mechanisms and/or vestibular pathways (tonic/phasic). The ability to increase the aVOR gain during vergence is not prognostic for successful adaptation training.
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Affiliation(s)
- Béla Büki
- Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria
| | - László T Tamás
- Department of Otolaryngology, Petz Aladár Teaching Hospital, Györ, Hungary
| | - Christopher J Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, Maryland
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, Australia.,Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
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Vergence increases the amplitude of lateral ocular vestibular evoked myogenic potentials. Exp Brain Res 2021; 239:1337-1344. [PMID: 33655370 DOI: 10.1007/s00221-021-06056-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 02/03/2021] [Indexed: 10/22/2022]
Abstract
The angular and linear vestibulo-ocular reflex responses are greater when viewing near targets to compensate for the relatively larger translation of the eyes with respect to the target. Our aim was to measure vestibular evoked myogenic potentials using a lateral ocular electrode montage (oVEMP) with a laterally applied stimulus using a mini-shaker during both far- and near-viewing (vergence) distances to determine whether vergence affects the oVEMP response as it does the semicircular canal vestibulo-ocular reflex response. Our results show that during vergence, the p1 and n1-p1 amplitude of the lateral oVEMP response increases significantly, whereas the latencies do not change significantly. We suggest that the physiological basis for this vergence-mediated amplitude increase in potentials may be the same as those already documented using transient linear head accelerations. Our data also suggest that irregular vestibular afferents are likely mediating the vergence-mediated gain increase during linear head accelerations because only irregular afferents are stimulated during short, transient 500 Hz stimuli.
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Van Nechel C, Bostan A, Duquesne U, Hautefort C, Toupet M. Visual Input Is the Main Trigger and Parametric Determinant for Catch-Up Saccades During Video Head Impulse Test in Bilateral Vestibular Loss. Front Neurol 2019; 9:1138. [PMID: 30662427 PMCID: PMC6328459 DOI: 10.3389/fneur.2018.01138] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/10/2018] [Indexed: 11/13/2022] Open
Abstract
Patients with vestibular deficit use slow eye movements or catch-up saccades (CUS) to compensate for impaired vestibulo-ocular reflex (VOR). The purpose of CUS is to bring the eyes back to the visual target. Covert CUS occur during high-velocity head rotation and overt CUS are generated after head rotation has stopped. Dynamic visual acuity is improved with an increased rate and gain of CUS. Nevertheless, the trigger and the parametric determinants of CUS are still under debate. To clarify the underlying mechanism, especially the visual contribution, we analyzed the number, amplitude and latencies of the CUS in relation with the extent of VOR deficiency. The head and eye movements were recorded in 17 patients with bilateral vestibular loss (BVL) and in 33 subjects with normal VOR gain using the Video Head Impulse Test (vHIT) in two conditions: with visible target and in darkness with an imaginary target. Our study shows that in darkness without visible target the number of CUS is significantly reduced and the relationship between the amplitude of CUS and gaze position error is lost. Results showed that there is a correlation between the number of CUS and the drop in VOR gain. CUS occurring during the head movement and when the head remained still were not always sufficiently accurate. Up to four consecutive CUS could be required to bring eyes back to the visible target. A positive correlation was found between the amplitude of overt saccades with visible target and the gaze position error, namely the remaining eye movement to reach the target. These results suggest that the visual inputs are the main trigger and parametric determinant of the CUS or at least the presence of a visual target is necessary in most cases for a CUS to occur.
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Affiliation(s)
- Christian Van Nechel
- Unité Troubles de l'Equilibre et Vertiges, Centre Hospitalier Universitaire Brugmann, Brussels, Belgium.,Unité de Neuro-Ophtalmologie, Hôpital Erasme, Brussels, Belgium.,Institut de Recherche Oto-Neurologique (IRON), Paris, France.,Clinique des Vertiges, Brussels, Belgium
| | - Alionka Bostan
- Unité Troubles de l'Equilibre et Vertiges, Centre Hospitalier Universitaire Brugmann, Brussels, Belgium.,Unité de Neuro-Ophtalmologie, Hôpital Erasme, Brussels, Belgium
| | - Ulla Duquesne
- Institut de Recherche Oto-Neurologique (IRON), Paris, France.,Clinique des Vertiges, Brussels, Belgium
| | - Charlotte Hautefort
- Institut de Recherche Oto-Neurologique (IRON), Paris, France.,Service ORL, APHP CHU Lariboisière, Paris, France
| | - Michel Toupet
- Institut de Recherche Oto-Neurologique (IRON), Paris, France.,Centre d'Explorations Fonctionnelles Otoneurologiques, Paris, France
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Judge PD, Rodriguez AI, Barin K, Janky KL. Impact of Target Distance, Target Size, and Visual Acuity on the Video Head Impulse Test. Otolaryngol Head Neck Surg 2018; 159:739-742. [PMID: 29865935 DOI: 10.1177/0194599818779908] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The video head impulse test (vHIT) assesses the vestibulo-ocular reflex. Few have evaluated whether environmental factors or visual acuity influence the vHIT. The purpose of this study was to evaluate the influence of target distance, target size, and visual acuity on vHIT outcomes. Thirty-eight normal controls and 8 subjects with vestibular loss (VL) participated. vHIT was completed at 3 distances and with 3 target sizes. Normal controls were subdivided on the basis of visual acuity. Corrective saccade frequency, corrective saccade amplitude, and gain were tabulated. In the normal control group, there were no significant effects of target size or visual acuity for any vHIT outcome parameters; however, gain increased as target distance decreased. The VL group demonstrated higher corrective saccade frequency and amplitude and lower gain as compared with controls. In conclusion, decreasing target distance increases gain for normal controls but not subjects with VL. Preliminarily, visual acuity does not affect vHIT outcomes.
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Affiliation(s)
- Paul D Judge
- 1 University of Nebraska Medical Center, Omaha, Nebraska, USA
| | | | - Kamran Barin
- 3 Eye and Ear Institute, The Ohio State University, Columbus, Ohio, USA
| | - Kristen L Janky
- 2 Boys Town National Research Hospital, Omaha, Nebraska, USA
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Anson ER, Kiemel T, Carey JP, Jeka JJ. Eye Movements Are Correctly Timed During Walking Despite Bilateral Vestibular Hypofunction. J Assoc Res Otolaryngol 2017; 18:591-600. [PMID: 28593438 DOI: 10.1007/s10162-017-0626-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 05/15/2017] [Indexed: 12/12/2022] Open
Abstract
Individuals with bilateral vestibular hypofunction (BVH) often report symptoms of oscillopsia (the perception that the world is bouncing or unstable) during walking. Efference copy/proprioception contributes to locomotion gaze stability in animals, sometimes inhibiting the vestibulo-ocular reflex (VOR). Gaze stability requires both adequate eye velocity and appropriate timing of eye movements. It is unknown whether eye velocity (VOR gain), timing (phase), or both are impaired for individuals with BVH during walking. Identifying the specific mechanism of impaired gaze stability can better inform rehabilitation options. Gaze stability was measured for eight individuals with severe BVH and eight healthy age- and gender-matched controls while performing a gaze fixation task during treadmill walking. Frequency response functions (FRF) were calculated from pitch eye and head velocity. A one-way ANOVA was conducted to determine group differences for each frequency bin of the FRF. Pearson correlation coefficients were calculated to determine the relationship between the real and imaginary parts of the FRF and the Oscillopsia Visual Analog Scale (oVAS) scores. Individuals with BVH demonstrated significantly lower gains than healthy controls above 0.5 Hz, but their phase was ideally compensatory for frequencies below 3 Hz. Higher oVAS scores were correlated with lower gain. Individuals with BVH demonstrated ideal timing for vertical eye movements while walking despite slower than ideal eye velocity when compared to healthy controls. Rehabilitation interventions focusing on enhancing VOR gain during walking should be developed to take advantage of the intact timing reported here. Specifically, training VOR gain while walking may reduce oscillopsia severity and improve quality of life.
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Affiliation(s)
- Eric R Anson
- Department of Otolaryngology Head and Neck Surgery and the David M. Rubinstein Hearing Center, Johns Hopkins School of Medicine, Baltimore, MD, USA. .,Johns Hopkins Outpatient Center, 601 N. Caroline Street, Ste 6030D, Baltimore, MD, 21287, USA.
| | - Tim Kiemel
- Kinesiology Department, University of Maryland, College Park, MD, USA
| | - John P Carey
- Department of Otolaryngology Head and Neck Surgery and the David M. Rubinstein Hearing Center, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - John J Jeka
- Department of Kinesiology, Temple University, Philadelphia, 19122, PA, United States.,Department of Bioengineering, Temple University, Philadelphia, PA, USA.,Shriners Hospital for Children, Philadelphia, PA, USA
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Fadaee SB, Migliaccio AA. The effect of retinal image error update rate on human vestibulo-ocular reflex gain adaptation. Exp Brain Res 2015; 234:1085-94. [DOI: 10.1007/s00221-015-4535-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 12/15/2015] [Indexed: 10/22/2022]
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A novel and inexpensive digital system for eye movement recordings using magnetic scleral search coils. Med Biol Eng Comput 2015; 54:421-30. [PMID: 26077529 DOI: 10.1007/s11517-015-1326-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 06/03/2015] [Indexed: 10/23/2022]
Abstract
After their introduction by Robinson (IEEE Trans Biomed Eng 10:137-145, 1963), magnetic scleral search coils quickly became an accepted standard for precise eye movement recordings. While other techniques such as video-oculography or electro-oculography may be more suitable for routine applications, search coils still provide the best low-noise and low-drift characteristics paired with the highest temporal and spatial resolution. The problem with search coils is that many research laboratories still have their large and expensive coil systems installed and are acquiring eye movement data with old, analog technology. Typically, the number of recording channels is limited and modifications to an existing search coil system can be difficult. We propose a system that allows to retro-fit an existing analog search coil system to become a digital recording system. The system includes digital data acquisition boards and a reference coil as the hardware part, receiver software, and a new calibration method. The circuit design has been kept simple and robust, and the proposed software calibration allows the calibration of a single coil within a few seconds.
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