Affiliations: [a] EFEE - Center for children balance disorders evaluation. ENT Departement, Robert Debré Universitary Hospital , 48, Bld Sérurier, 75019 Paris, France
| [b] UMR 7114 MoDyCo, CNRS-Université Paris Nanterre. Nanterre, France
| [c] CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
Correspondence:
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Corresponding authors. Moetez Baghdadi, EFEE - Center for children balance disorders evaluation. ENT Departement, Robert Debré Hospital, 48, Bld Sérurier, 75019 Paris, France. E-mail: moetez.baghdadi@gmail.com and Sylvette R. Wiener-Vacher, EFEE - Center for evaluating balance disorders in children, ENT Department, Robert Debré University Hospital, 48, Bld Sérurier, 75019 Paris, France; E-mail: sylvette.wiener@gmail.com.
Abstract: Highlights• The estimation of verticality (assessed with Subjective visual vertical (SVV)) is more variable in patients with Usher (type I and II) compared to healthy participants.• Visual and vestibular information are essential for the visual vertical (VV) perception.• A reweighting of sensory information from the central nervous system seems to be able to compensate for the absence of vestibular function in patients with Usher type I. BACKGROUND:Verticality, or more precisely the ability to perceive spatial orientation with regard to gravity, is based on the integration of visual, vestibular and somesthetic information. OBJECTIVE:The purpose of the present study was to compare the subjective visual vertical (SVV) in patients with Usher (type I and type II) with visual or vestibular impairment, and in healthy participants, in order to explore the importance of the visual and vestibular functions on the vertical’s perception. METHODS:We evaluated the SVV using a wall housing which projects on the opposite wall a red-light line of about 2 meters, obtained by laser cannon. The evaluation was carried out under two tilt conditions: clockwise and counter-clockwise randomly performed five times in each direction. The response to the SVV task was quantified by the mean of the absolute values of the SVV. RESULTS:Responses to the SVV were significantly less accurate in patients with Usher with respect to healthy participants while it was similar for the two groups of patients with Usher. CONCLUSIONS:We hypothesize that visual inputs play a very important role in the perception of verticality and that the symmetrical bilateral vestibular deficit in Usher type I does not have a strong impact in perception of verticality.
