Effects of vestibular disorders on vestibular reflex and imagery

Abstract

The aim of this study was to establish the effect of vestibular lesion on vestibular imagery. Subjects were required to estimate verbally their passively travelled rotation angles in complete darkness, i.e., to activate vestibular imagery. During motion, the vestibulo-ocular reflex (VOR) was measured. Thus, we examined the coherence between the vestibulo-ocular reflex and self-rotation imagery, with vestibular-lesioned patients and healthy participants. Unilateral acute and chronic patients, bilateral patients, and healthy subjects were compared. The stimulus was a sequence of eight successive passive rotations, with four amplitudes (from 90° to 360°) in two directions. The VOR gain was lower in patients with unilateral lesions, for ipsilateral rotations. The healthy subjects had the highest gain and the bilateral group the lowest, on both rotation sides. Thanks to vestibular compensation after acute unilateral neuritis, the VOR gain increased in lesion side and decreased in healthy side, resulting in a similar gain in both sides. A deficit of vestibular imagery was found exclusively in patients with bilateral hyporeflexia, on both sides. The performance in vestibular imagery was good in the control group and correct in the unilateral patients. Finally, we found a significant correlation between the efficiency of the VOR and that of vestibular imagery, exclusively in the bilateral patients. The present study shows the complex relationship between vestibular imagery and the VOR. This imagery test contributes to another assessment of the spatial handicap of vestibular patients. It seems particularly interesting for patients with bilateral canal paresis and could be used to confirm this diagnosis.

Impaired Duration Perception in Patients With Unilateral Vestibulopathy During Whole-Body Rotation

“…The first observation was that the patient group showed normal position and velocity/acceleration perception. A previous experiment with repetitive rotations from 90 • to 360 • with a 90 • interval showed that patients with acute and chronic unilateral vestibulopathy had intact position estimates in ipsilesional and contralesional rotations (Cohen et al, 2017). Therefore, the position estimation in this study using more fractionalized intervals reaffirmed the previous findings.…”

“…Of interest, the VOR pathway remained compromised in previous and current studies (Cousins et al, 2013;Cohen et al, 2017), which could support that the recovery of the VP pathway is more robust than that of the VOR pathway. The VP and VOR pathways have been known to share a velocity storage circuit (Bertolini et al, 2012).…”

“…In position estimation tests with rotational vestibular stimuli, healthy individuals tended to underestimate with a gain of about 0.8-0.9 (Kaski et al, 2016;Choi et al, 2021). In a similar experimental setting, patients with unilateral vestibulopathy also had a position estimate comparable to healthy individuals in both acute and chronic stages (Cohen et al, 2017). Regarding duration perception, a decreased duration perception for motion in the acute phase of unilateral vestibulopathy nearly recovered in the chronic phase (Cousins et al, 2013).…”

The Role of Different Afferent Systems in the Modulation of the Otolith-Ocular Reflex After Long-Term Space Flights

“…This can even take place at the cortical level, as shown in a parabolic flight study ( Demertzi et al, 2015 ; Van Ombergen et al, 2017 ). Similar inhibition of VOR gains during rotation to the healthy side are observed in the early phase of a vestibular neuritis in dizzy patients to limit the degree of asymmetry ( Cohen et al, 2017 ). This could be a first reason why the OCR is reduced during centrifugation compared to a static body or head tilt.…”

“…Recovery, after return to Earth, takes some time during which there is a readaptation of the otolith function to the Earth's gravitational level of 1 g take place (Kornilova et al, 2012(Kornilova et al, , 2017. It is known that in these recovery processes, the nodulus and uvula of the cerebellum play an important role (Cohen et al, 2002(Cohen et al, , 2019.…”