Journal of Vestibular Research-Equilibrium & Orientation最新文献

Perception of self-motion involves the integration of visual and vestibular sensory information. Currently, there is limited research exploring visual-vestibular interactions under weak vestibular stimulation. This study investigates the impact of weak inertial stimulation on visual-vestibular bimodal heading perception. A translational XY-axis motion platform equipped with a 46-inch LCD TV was utilized to generate synchronized visual and inertial stimuli. The heading perception was examined under visual-only, vestibular-only, and bimodal conditions using three levels of inertial stimuli (9 mg, 14 mg, and 19 mg). In each condition, participants were tested at nine angles (±16°, ±9.2°, ±3°, ±1.7°, and 0° where 0° represents forward movement), to discern left-forward or right-forward motion. The heading discrimination threshold (HDT) was derived from participants' rightward response proportions across all angles. Our findings reveal that the HDT under 14 mg bimodal conditions is significantly higher than that under visual-only conditions (with marginal significance in the 9 mg and 19 mg conditions), indicating that the presence of weak vestibular signals might decrease the precision of bimodal heading discrimination. These results contradict the prediction of Bayesian model theory that perception is more precise under bimodal compared with unimodal conditions. The results may be explained by neurological biases during Bayesian integration, the "reduced visual precision" theory, or increased task complexity in bimodal heading discrimination. Further research with larger sample size, extending the study to varied inertial stimuli and visual coherence levels, will be beneficial for clarifying its underlying mechanisms.

BackgroundPatients with persistent postural-perceptual dizziness (PPPD) exhibit altered postural and gait dynamics, but development of these changes following precipitating illnesses is poorly understood.ObjectiveTo compare posture and gait metrics in patients with PPPD or subacute unilateral vestibulopathies (sAUVP) to healthy controls (HC).MethodsTen patients with sAUVP, nine with PPPD, and eleven HC completed the 10 Meters Walk Test (10MWT) (an eyes open task) and Fukuda Stepping Test (FST) (an eyes closed task). Gait stability, symmetry, and smoothness were compared among groups and correlated with Dizziness Handicap Inventory (DHI) scores.Results10MWT - Patients with PPPD had lower pelvis stability and gait symmetry than HCs. Patients with sAUVP had only lower pelvis stability. FST - Patients with PPPD and sAUVP had lower gait smoothness than HCs. Patients with sAUVP also had lower gait symmetry. Among patients with PPPD, DHI scores correlated positively with head stability.ConclusionsPPPD and sAUVP caused abnormal pelvis stability when walking and gait smoothness when stepping but differed in effects on gait symmetry with the presence/absence of visual inputs. For PPPD, visual stimuli had destabilizing effects, whereas for sAUVP vision aided stability. Symptom severity in patients with PPPD was related to head stability.

BackgroundThe efficacy of corticosteroids for treating acute vestibular neuritis, or acute unilateral vestibulopathy (AUVP), remains controversial.ObjectiveThis study aimed to evaluate whether corticosteroids improve vestibular function and reduce symptoms in both acute and chronic phases of AUVP.MethodsThis randomized, placebo-controlled, double-blind trial included patients with AUVP (ages 18-80) from emergency departments at three sites in southern Sweden. Patients were randomly assigned to one of three groups: placebo, 3-day or 10-day corticosteroid treatment. The steroid groups received intravenous betamethasone followed by oral steroids, while the placebo group received intravenous saline followed by oral placebo. The primary outcome was canal paresis (%) after 12 months, measured via caloric testing. Secondary outcomes included vHIT gain, Diary Vertigo score, Dizziness Handicap Inventory, and Hospital Anxiety and Depression Scale. Analyses were conducted on an intention-to-treat basis. The trial was registered with the EU Clinical Trials Register (EudraCT Number: 2014-005484-32) and ClinicalTrials.gov (NCT00802529).ResultsFrom December 2015 to March 2021, 350 patients were screened, and 69 were included: 23 in the 10-day corticosteroid group, 22 in the 3-day corticosteroid group, and 24 in the placebo group. All groups showed significant improvement in caloric function over time (p = .002), with no significant differences between groups at any time point (p = .629). Change in caloric asymmetry from baseline to 12 months did not differ between the treatment groups and the placebo group: mean difference -8.34 (95% CI -25.93 to 9.26; p = .347) in the 10-day steroid group and -6.61 (-24.67 to 11.45; p = .467) in the 3-day steroid group, compared with placebo. Secondary outcomes showed no significant differences between groups. Corticosteroid treatments were well tolerated with no safety concerns.ConclusionsCorticosteroid treatment does not significantly improve caloric recovery, vHIT gain recovery, or subjective well-being in patients with AUVP.

BackgroundVestibular neuritis (VN) has faced various diagnostic challenges despite years of clinical use. This study analyzes 65 cases based on diagnostic criteria for acute unilateral vestibulopathy/vestibular neuritis (AUVP/VN) 2022.MethodThrough medical history, physical examinations, and vestibular function tests, including the caloric test, video-head impulse test (v-HIT), and vestibular evoked myogenic potentials (VEMPs), we thoroughly tested vestibular receptor dysfunction of AUVP/VN cases. Patients were divided into two groups: total vestibular nerve branch dysfunction (tVND) and partial vestibular nerve branch dysfunction (pVND). The tVND group was defined as involving all receptors innervated by the superior and/or inferior vestibular nerve. The pVND group was defined as involving any other combination pattern of vestibular receptors (at least one). Sociodemographic and clinical characteristics were analyzed. All patients were followed up for 6 months. Changes in DHI scale scores and residual or new symptoms were investigated.ResultsA total of 65 AUVP/VN patients with vestibular receptor dysfunction were included. There were 51 cases in the pVND group and 14 in the tVND group. Compared to the pVND group, the tVND group showed longer vertigo duration (p < 0.05), higher rates of postural symptoms (p < 0.01), higher rates of abnormal caloric tests (p < 0.05), higher canal paresis values (p < 0.001), and higher rates of deficient vestibulo-ocular reflex (VOR) gain in v-HIT (p < 0.001). After a 6-month follow-up, the pVND group showed lower DHI scores (p < 0.001) and higher cure rate (p < 0.001).ConclusionsIn general, patients in the tVND group showed a more severe disease and worse prognosis than those in the pVND group. The substitution of the term AUVP for VN is appropriate and aligns with the clinical characteristics of the cases. However, the diagnosis of AUVP should be further developed to include otolith organ dysfunction.

BackgroundMotion sickness (MS) is a clinical condition that causes autonomic symptoms as a result of a mismatch in sensory inputs with unusual body and environmental movements. Although the cause of MS is not clearly established, one widely accepted theory is otolith asymmetry and canal-otolith conflict. Masseteric vestibular evoked myogenic potentials (mVEMPs) are short latency inhibitory potentials recorded from the bilateral masseter muscle in response to bilateral or unilateral galvanic/acoustic stimuli. Studies have shown that mVEMP evaluates the integrity of the vestibulo-trigeminal pathway and the generator region is the saccule in common with cVEMP.ObjectiveOur study aimed to evaluate the function of the otolith organ and vestibulo-trigeminal pathway in people with high susceptibility to MS via mVEMP.MethodsAccording to the Motion Sickness Susceptibility Questionnaire-Short Form (MSSQ-SF), 21 people with 70-100% susceptibility (high susceptibility) and 20 people with 0-30% susceptibility (low susceptibility) were included in the study. Participants have normal hearing and do not have any additional disorders. All participants underwent mVEMP evaluation.ResultsThere was no statistical difference in P1, N1 absolute latency, N1-P1 inter-wave latency, N1-P1 amplitude, interaural amplitude asymmetry ratios at 100 dB nHL, and mVEMP thresholds in the high and low susceptibility groups.ConclusionsOur study obtained no findings suggesting saccule and vestibulo-trigeminal involvement in people high susceptible to motion sickness.

BackgroundSound stimulation can influence electrophysiological vestibular reflexes. However, the effects of sound stimulation on space perception remain unknown.ObjectiveTo know the effects of monaural sound stimulation on subjective visual vertical (SVV).MethodsWe measured SVV with and without monaural sound stimulation (105 dB, 500 Hz short tone burst presented at 4.7 Hz) in 50 healthy volunteers (aged 20-77 [mean = 42.7] years).ResultsThe mean SVV was deviated 0.139° to the left by right monaural sound stimulation and 0.123° to the right by left monaural sound stimulation. SVV changes due to right and left ear stimulations were significantly different (p = 0.019). Sound stimulation resulted in a significant change in SVV on the left side (p = 0.014) in participants aged 50 or younger (mean = 35.6 years) (n = 37).ConclusionsThis study is the first to show the possibility that the monaural sound input deviates the SVV toward the opposite side and is more pronounced for left-ear input. The vestibular-evoked myogenic potential responses may be involved in the mechanism of the contralateral SVV deviation due to sound input.

BackgroundFlight simulators have an essential role in aircrew training. Occasionally, symptoms of motion sickness, defined as simulator sickness, develop during training sessions. The reported incidence of simulator sickness ranged widely in different studies.ObjectiveThe aims of this study were to calculate the incidence of and to define a threshold value for simulator sickness among rotary-wing pilots using the validated Simulator Sickness Questionnaire (SSQ).MethodsCH-53 and UH-60 helicopter pilots, who trained in helicopter simulators in the Israeli Air Force, were asked to fulfill SSQ. A score of 20 in the SSQ was defined as the threshold for simulator sickness. Simulator sickness incidence and average SSQ were calculated. Correlations between age and simulator training hours to SSQ scores were analyzed.ResultsA total of 207 rotary-wing aircrew participated in the study. Simulator sickness was experienced by 51.7% of trainees. The average SSQ score was 32.7. A significant negative correlation was found between age and SSQ score.ConclusionsSimulator sickness was experienced by more than half of helicopter pilots. A score of 20 in the SSQ was found to be suitable as the threshold for this condition.

BackgroundVestibular migraine (VM) is a common cause of recurrent spontaneous and positional dizziness of varying durations. Short episodes of VM lasting seconds to minutes, triggered by changes in head position can resemble those of benign paroxysmal positioning vertigo (BPPV), while episodes lasting minutes to hours can mimic those of Meniere's disease (MD).ObjectiveWe aimed to compare symptoms and vestibular test results in patients with VM, BPPV and MD, where VM was categorized by episode duration.MethodsWe compared vestibular, aural and migraine symptoms, as well as cervical and ocular vestibular evoked myogenic potentials and 3D video head impulse tests, in 108 patients: 24 with BPPV, 33 with VM episodes of short duration (<10 min), 29 with VM of medium duration (≥10 min) and 22 with MD.ResultsWe found significant overlap in the symptoms of all patient groups, and no significant differences between patients with short and medium VM. Abnormal test results occurred infrequently in all groups.ConclusionsOur results confirm significant symptom overlap between BPPV or MD and VM, and suggest that VM mimics other conditions when the episode duration matches the differential diagnosis, rather than because patients with different durations of vertigo have different symptoms.

BackgroundThe video head impulse test (vHIT) is vital in clinical setting for assessing vestibulo-ocular reflex (VOR) function in patients of all ages. However, how normal aging influence VOR gain and catch-up saccades remains unclear, thus leading to confusion in interpretation of vHIT results.ObjectiveThis study aims to compare VOR gain and saccades parameters (frequency, amplitude, and latency) between younger and older adults, while maintaining head velocity and acceleration within the same range.MethodsA total of 24 younger and 24 older adults performed horizontal vHIT tests (ICS Impulse, Otometrics, Denmark). Gain and saccades were analyzed using a custom MATLAB script. Three VOR gain algorithms were compared: Area under the curve (AUC), instantaneous gain, and regression gain.ResultsIn our sample, no significant differences in the VOR gains were observed between younger and older adults using any of the algorithms. Compared to younger adults, older adults had saccades that were significantly more frequent, of greater amplitude, and of shorter latencies. However, a larger sample size is needed to confirm the lack of aging effect on VOR gains.ConclusionsThe absence of significant effects of aging on VOR gain in vHIT demonstrates that all three gain algorithms should provide similar values for patients across all ages in clinical practice. The results suggest that small saccades in older adults are unrelated to head impulse parameters, and the mechanisms behind this increase in saccades with normal aging remain to be explored.