Vestibular Perception following Acute Unilateral Vestibular Lesions

Abstract

Little is known about the vestibulo-perceptual (VP) system, particularly after a unilateral vestibular lesion. We investigated vestibulo-ocular (VO) and VP function in 25 patients with vestibular neuritis (VN) acutely (2 days after onset) and after compensation (recovery phase, 10 weeks). Since the effect of VN on reflex and perceptual function may differ at threshold and supra-threshold acceleration levels, we used two stimulus intensities, acceleration steps of 0.5°/s2 and velocity steps of 90°/s (acceleration 180°/s2). We hypothesised that the vestibular lesion or the compensatory processes could dissociate VO and VP function, particularly if the acute vertiginous sensation interferes with the perceptual tasks. Both in acute and recovery phases, VO and VP thresholds increased, particularly during ipsilesional rotations. In signal detection theory this indicates that signals from the healthy and affected side are still fused, but result in asymmetric thresholds due to a lesion-induced bias. The normal pattern whereby VP thresholds are higher than VO thresholds was preserved, indicating that any ‘perceptual noise’ added by the vertigo does not disrupt the cognitive decision-making processes inherent to the perceptual task. Overall, the parallel findings in VO and VP thresholds imply little or no additional cortical processing and suggest that vestibular thresholds essentially reflect the sensitivity of the fused peripheral receptors. In contrast, a significant VO-VP dissociation for supra-threshold stimuli was found. Acutely, time constants and duration of the VO and VP responses were reduced – asymmetrically for VO, as expected, but surprisingly symmetrical for perception. At recovery, VP responses normalised but VO responses remained shortened and asymmetric. Thus, unlike threshold data, supra-threshold responses show considerable VO-VP dissociation indicative of additional, higher-order processing of vestibular signals. We provide evidence of perceptual processes (ultimately cortical) participating in vestibular compensation, suppressing asymmetry acutely in unilateral vestibular lesions.

Peripheral Vestibular Dysfunction in Patients With Primary Ciliary Dyskinesia

“…We also observed an intact VOR in response to angular rotation (rVOR) in all 5 PCD subjects, confirming the presence of bilateral vestibular function. Upon rotational testing, however, the VOR time constant (which reflects vestibulo-central processing [18] and is typically 13-16s long [19]) was borderline reduced in subjects 1, 4 and 5 (Table 2), similar to that seen in vestibular disorders (such as acute vestibular neuritis [20]) and motion-habituated professionals [21]. Perhaps the slight reduction in semicircular canal function points towards reciprocal inhibition to manage the otoconia-semicircular canal mismatch [22,23].…”

“…We have chosen to use a step rotation at 90°/s to maintain consistency with our previous studies [20,31] and others of the velocity storage mechanism [32]. One measure of the velocity storage system is the vestibular velocity storage mechanism.…”

“…One measure of the velocity storage system is the vestibular velocity storage mechanism. We have chosen this measure because the time constant can reflect vestibular impairment by disease [20,33], intervention [31] and drug effects [21,[34][35][36]]. However, it should be pointed out that the time constant can habituate which lends itself to poor repeatability.…”

Effects of Prochlorperazine on Normal Vestibular Ocular and Perceptual Responses: A Randomised, Double-Blind, Crossover, Placebo-Controlled Study

“…EOG signals were passed through a low-pass filter (cut-off 30 Hz) prior to analysis. The nystagmic or vestibulo-ocular threshold, i.e., onset time of nystagmus, was obtained from the raw eye movement trace and a differentiated and de-saccaded eye movement trace [(see Cousins et al, 2013, andOkada et al, 1999), for further technical details].…”

Glucocorticoids improve acute dizziness symptoms following acute unilateral vestibulopathy

“…Despite asymmetrical VOR time constants following an acute vestibulopathy, recent evidence has shown a considerable dissociation between vestibulo-ocular and vestibulo-perceptual thresholds (i.e. the perception of self-motion) [7]. This poses the question of whether restoring the vestibular tone imbalance acutelyand thus reducing nystagmus -through a reduction in inflammation would have any effect on dizziness symptoms (i.e.…”