Electrophysiological and inner ear MRI findings in patients with bilateral vestibulopathy.

PURPOSE: Bilateral vestibulopathy (BV) is an uncommon disorder and the etiology remained idiopathic in most cases. Delayed 3D-FLAIR sequences have provided new insights into various inner ear diseases, allowing the evaluation of the endolymphatic space and the permeability of the blood-labyrinthine barrier (BLB). The aim of this study was to assess both the morphology of the endolymphatic space and the permeability of the BLB in patients with BV as evaluated by delayed 3D-FLAIR sequences. METHODS: In this retrospective study, we performed 3D-FLAIR sequences 4 h after administering contrast media to 42 patients with BV. Two radiologists independently evaluated the morphology of the endolymphatic space (either vestibular atelectasis or endolymphatic hydrops) and the permeability of the BLB. RESULTS: Morphologic anomalies of the endolymphatic space and vestibular blood-labyrinthine barrier impairment were observed in 59.6% of patients with BV. Bilateral vestibular atelectasis (VA) was found in 21 patients (50%), involving only the utricle and all three ampullas while the saccule was always observed with no sign of collapse: idiopathic BV (n = 19), aminoglycoside administration (n = 1) and few days following abdominal surgery (n = 1). One patient had bilateral vestibular malformation. BLB impairment was observed in five patients (11.9%): paraneoplastic (n = 1), lymphoma (n = 1), autoimmune (n = 1), and vestibular "neuritis" (n = 2). Seventeen patients (40.4%) had normal MRI with no endolymphatic space anomaly or BLB impairment. CONCLUSION: Patients with BV presented with morphologic anomalies of the endolymphatic space or BLB impairment in 59.6% of patients.

Influence of Visual and Vestibular Hypersensitivity on Derealization and Depersonalization in Chronic Dizziness.

Objective: The aim of this study was to investigate the relation between visual and vestibular hypersensitivity, and Depersonalization/Derealization symptoms in patients with chronic dizziness. Materials and Methods: 319 adult patients with chronic dizziness for more than 3 months (214 females and 105 males, mean age: 58 years, range: 13-90) were included in this prospective cross-sectional study. Patients underwent a complete audio-vestibular workup and 3 auto questionnaires: Hospital Anxiety and Depression (HAD), Depersonalization/Derealization Inventory (DDI), and an in-house questionnaire (Dizziness in Daily Activity, DDA) assessing 9 activities with a score ranging from 0 (no difficulty) to 10 (maximal discomfort) and 11 (avoidance) to detect patients with visual and vestibular hypersensitivity (VVH, a score > 41 corresponding to mean + 1 standard deviation). Results: DDI scores were higher in case of VVH (6.9 ± 6.79, n = 55 vs. 4.2 ± 4.81, n = 256 without VVH, p < 0.001, unpaired t-test), migraine (6.1 ± 6.40, n = 110 vs. 4.0 ± 4.42, n = 208no migraine, p < 0.001, unpaired t-test), and motion sickness (6.8 ± 5.93, n = 41 vs. 4.4 ± 5.11, n = 277 no motion sickness, p < 0.01, unpaired t-test). Women scored DDI higher than men (5.1 ± 5.42, n = 213 vs. 3.9 ± 4.91, n = 105, respectively, p < 0.05, unpaired t-test). DDI scores were also related to depression and anxiety. DDI score was also higher during spells than during the basal state. Conclusion: During chronic dizziness, Depersonalization/Derealization symptoms seem to be related to anxiety and depression. Moreover, they were prominent in women, in those with visual and vestibular hypersensitivity, migraine, and motion sickness.

Visual Input Is the Main Trigger and Parametric Determinant for Catch-Up Saccades During Video Head Impulse Test in Bilateral Vestibular Loss.

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.

Subjective Visual Vertical in Idiopathic Bilateral Vestibular Hypofunction: Enhanced Role of Vision, Neck, and Body Proprioception.

INTRODUCTION: We aimed to study the participation of proprioceptive and visual inputs in subjective visual vertical (SVV) in bilateral vestibular hypofunction and in normal subjects. STUDY DESIGN: Prospective case-control study. SETTING: Tertiary referral center. MATERIALS AND METHODS: SVV (six replicates) was measured on a tiltable rehabilitation seat in 26 adult patients with idiopathic bilateral vestibular hypofunction (IBVH) and 33 adult controls. Subjects were asked to place vertically a 45 degrees-tilted red line on a screen (three replicates to left and three to right alternatively) using a remote control in total darkness and in seven body positions: vertical, head, and body left- and right-tilts to 12 and 24 degrees, and then body left- and right-tilt to 24 degrees with the head upright. RESULTS: In the vertical position, SVV did not differ between IBVH and controls. Patients with IBVH were more sensitive to body tilt than controls (SVV: -8.1 ±â€Š4.66 degrees for IBVH versus -0.2 ±â€Š3.23 for control at 24 degrees body and head left-tilt, p < 0.0001, unpaired t test). The visual attraction effect defined by a deviation of the SVV to the side of the initial line presentation appeared to be higher in the IBVH than in controls suggesting higher visual dependence in IBVH. Placing the head upright while the body was still tilted significantly reduced this difference. Similar results were observed for the right-tilts. CONCLUSION: Not only otolithic function but also visual plus body and neck proprioceptive entries participate in SVV. The influence of vision and proprioception appears to be enhanced in case of IBVH.

Anchoring the Self to the Body in Bilateral Vestibular Failure.

Recent findings suggest that vestibular information plays a significant role in anchoring the self to the body. Out-of-body experiences of neurological origin are frequently associated with vestibular sensations, and galvanic vestibular stimulation in healthy participants anchors the self to the body. Here, we provide the first objective measures of anchoring the self to the body in chronic bilateral vestibular failure (BVF). We compared 23 patients with idiopathic BVF to 23 healthy participants in a series of experiments addressing several aspects of visuo-spatial perspective taking and embodiment. In Experiment 1, participants were involved in a virtual "dot-counting task" from their own perspective or the perspective of a distant avatar, to measure implicit and explicit perspective taking, respectively. In both groups, response times increased similarly when the avatar's and participant's viewpoint differed, for both implicit and explicit perspective taking. In Experiment 2, participants named ambiguous letters (such as "b" or "q") traced on their forehead that could be perceived from an internal or external perspective. The frequency of perceiving ambiguous letters from an internal perspective was similar in both groups. In Experiment 3, participants completed a questionnaire measuring the experienced self/body and self/environment "closeness". Both groups reported a similar embodied experience. Altogether, our data show that idiopathic BVF does not change implicit and explicit perspective taking nor subjective anchoring of the self to the body. Our negative findings offer insight into the multisensory mechanisms of embodiment. Only acute peripheral vestibular disorders and neurological disorders in vestibular brain areas (characterized by strong multisensory conflicts) may evoke disembodied experiences.