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Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?

The vestibulo-ocular reflex maintains gaze stabilization during angular or linear head accelerations, allowing adequate dynamic visual acuity. In case of bilateral vestibular hypofunction, patients use saccades to compensate for the reduced vestibulo-ocular reflex function, with covert saccades occu...

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Autores principales: Hermann, R., Pelisson, D., Dumas, O, Urquizar, Ch, Truy, E., Tilikete, C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer US 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5966498/
https://www.ncbi.nlm.nih.gov/pubmed/29248983
http://dx.doi.org/10.1007/s12311-017-0907-0
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author Hermann, R.
Pelisson, D.
Dumas, O
Urquizar, Ch
Truy, E.
Tilikete, C.
author_facet Hermann, R.
Pelisson, D.
Dumas, O
Urquizar, Ch
Truy, E.
Tilikete, C.
author_sort Hermann, R.
collection PubMed
description The vestibulo-ocular reflex maintains gaze stabilization during angular or linear head accelerations, allowing adequate dynamic visual acuity. In case of bilateral vestibular hypofunction, patients use saccades to compensate for the reduced vestibulo-ocular reflex function, with covert saccades occurring even during the head displacement. In this study, we questioned whether covert saccades help maintain dynamic visual acuity, and evaluated which characteristic of these saccades are the most relevant to improve visual function. We prospectively included 18 patients with chronic bilateral vestibular hypofunction. Subjects underwent evaluation of dynamic visual acuity in the horizontal plane as well as video recording of their head and eye positions during horizontal head impulse tests in both directions (36 ears tested). Frequency, latency, consistency of covert saccade initiation, and gain of covert saccades as well as residual vestibulo-ocular reflex gain were calculated. We found no correlation between residual vestibulo-ocular reflex gain and dynamic visual acuity. Dynamic visual acuity performance was however positively correlated with the frequency and gain of covert saccades and negatively correlated with covert saccade latency. There was no correlation between consistency of covert saccade initiation and dynamic visual acuity. Even though gaze stabilization in space during covert saccades might be of very short duration, these refixation saccades seem to improve vision in patients with bilateral vestibular hypofunction during angular head impulses. These findings emphasize the need for specific rehabilitation technics that favor the triggering of covert saccades. The physiological origin of covert saccades is discussed.
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spelling pubmed-59664982018-06-04 Are Covert Saccade Functionally Relevant in Vestibular Hypofunction? Hermann, R. Pelisson, D. Dumas, O Urquizar, Ch Truy, E. Tilikete, C. Cerebellum Original Paper The vestibulo-ocular reflex maintains gaze stabilization during angular or linear head accelerations, allowing adequate dynamic visual acuity. In case of bilateral vestibular hypofunction, patients use saccades to compensate for the reduced vestibulo-ocular reflex function, with covert saccades occurring even during the head displacement. In this study, we questioned whether covert saccades help maintain dynamic visual acuity, and evaluated which characteristic of these saccades are the most relevant to improve visual function. We prospectively included 18 patients with chronic bilateral vestibular hypofunction. Subjects underwent evaluation of dynamic visual acuity in the horizontal plane as well as video recording of their head and eye positions during horizontal head impulse tests in both directions (36 ears tested). Frequency, latency, consistency of covert saccade initiation, and gain of covert saccades as well as residual vestibulo-ocular reflex gain were calculated. We found no correlation between residual vestibulo-ocular reflex gain and dynamic visual acuity. Dynamic visual acuity performance was however positively correlated with the frequency and gain of covert saccades and negatively correlated with covert saccade latency. There was no correlation between consistency of covert saccade initiation and dynamic visual acuity. Even though gaze stabilization in space during covert saccades might be of very short duration, these refixation saccades seem to improve vision in patients with bilateral vestibular hypofunction during angular head impulses. These findings emphasize the need for specific rehabilitation technics that favor the triggering of covert saccades. The physiological origin of covert saccades is discussed. Springer US 2017-12-16 2018 /pmc/articles/PMC5966498/ /pubmed/29248983 http://dx.doi.org/10.1007/s12311-017-0907-0 Text en © The Author(s) 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Original Paper
Hermann, R.
Pelisson, D.
Dumas, O
Urquizar, Ch
Truy, E.
Tilikete, C.
Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?
title Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?
title_full Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?
title_fullStr Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?
title_full_unstemmed Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?
title_short Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?
title_sort are covert saccade functionally relevant in vestibular hypofunction?
topic Original Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5966498/
https://www.ncbi.nlm.nih.gov/pubmed/29248983
http://dx.doi.org/10.1007/s12311-017-0907-0
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