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.

Objective: This study aimed to quantitatively analyze the characteristics of saccades in normal subjects during video head impulse test (vHIT), to establish a reference for clinical practice.

Methods: A cohort of 20 healthy individuals (40 ears) was recruited and compared with a matched group of 20 patients (20 ears) suffering from vestibular neuritis (VN), utilizing vHIT to evaluate the functionality of all three semicircular canals (SCCs). This study analyzed the quantitative characteristics of saccades observed in healthy individuals and patients with VN.

Results: Significant differences were observed between both groups in terms of lateral saccade frequency, latency, peak velocity, and duration for both the first and second saccades (all p < 0.05, with age as a covariate). Similarly, significant differences were found in vertical SCCs between groups for the frequency, latency, peak velocity, and duration of the first saccade (all p < 0.05, with age as a covariate). However, no significant differences were found in Perez-Rey (PR) scores either in lateral (p = 0.259) or vertical (p = 0.102) SCCs. Within the healthy group, significant differences were observed in the frequency, peak velocity, and duration of the first saccade in lateral and vertical SCCs (all p < 0.05). However, the latency (p = 0.827) and PR scores (p = 0.552) exhibited no significant variation.

Conclusions: Microsaccades characterized by prolonged latency and reduced amplitude can occur in healthy individuals during vHIT and are distinct from the saccades seen in patients with VN due to vestibular impairment. This highlights the need to carefully identify and interpret relevant saccades during clinical assessments.

Background: Vestibular 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.

Method: Through 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.

Results: A 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).

Conclusions: In 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.

Background: Patients with persistent postural-perceptual dizziness (PPPD) exhibit altered postural and gait dynamics, but development of these changes following precipitating illnesses is poorly understood.

Objective: To compare posture and gait metrics in patients with PPPD or subacute unilateral vestibulopathies (sAUVP) to healthy controls (HC).

Methods: Ten 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.

Results: 10MWT - 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.

Conclusions: PPPD 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.

Background: The 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.

Objective: This 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.

Methods: A 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.

Results: In 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.

Conclusions: The 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.

Background: Vestibular 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).

Objective: We aimed to compare symptoms and vestibular test results in patients with VM, BPPV and MD, where VM was categorized by episode duration.

Methods: We 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.

Results: We 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.

Conclusions: Our 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.

Background: Sound stimulation can influence electrophysiological vestibular reflexes. However, the effects of sound stimulation on space perception remain unknown.

Objective: To know the effects of monaural sound stimulation on subjective visual vertical (SVV).

Methods: We 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).

Results: The 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).

Conclusions: This 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.

Background: Flight 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.

Objective: The 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).

Methods: CH-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.

Results: A 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.

Conclusions: Simulator 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.

Background: Persistent postural-perceptual dizziness (PPPD) is a functional vestibular disorder that causes chronic dizziness and limits daily activities. Although pharmacology, vestibular rehabilitation, and cognitive behavioral therapy have been proposed to have some efficacy, they have certain limitations. Some patients with PPPD report that public square dancing can effectively relieve the symptoms of dizziness and instability, and their mood improves.

Objective: To evaluate the effects of combining public square dancing with serotonin reuptake inhibitors (SSRIs/SNRIs) on the subjective sensations of dizziness, balance enhancement, anxiety, and depressive symptom regulation in middle-aged and older women with PPPD.

Materials and methods: In this trial, 124 patients diagnosed with PPPD were enrolled. Among them, 64 patients were randomly assigned to the experimental group (EG), where they received square dance training combined with serotonin reuptake inhibitors. The remaining 60 cases were randomly assigned to the control group (CG), where they received only serotonin reuptake inhibitors and did not participate in organized sports activities, allowing them freedom in their daily lives. Data from the Dizziness Handicap Inventory (DHI), Hospital Anxiety and Depression Scale (HADS), Active-specific Balance Confidence Scale (ABC), and Vestibular Disorder Activities of Daily Living Scale (VADL) were collected and compared at the beginning, 3 months, and 6 months of the trial to evaluate the effect of public square dancing on middle-aged and older women with PPPD.

Results: There were no significant differences between the EG and CG before the trial. Compared with baseline measures, DHI, HADS, ABC, and VADL scores improved as the experiment progressed, and the improvements were more pronounced in the EG.

Conclusion: Public square dancing combined with serotonin reuptake inhibitors has a positive impact on the subjective sensations of dizziness, balance enhancement, anxiety, and depressive symptom regulation in middle-aged and older women with PPPD.

Objective: A normal video Head Impulse Test is the gold standard in the emergency department to rule-in patients with an acute vestibular syndrome and a stroke. We aimed to compare the diagnostic accuracy of vHIT metrics regarding the vestibulo-ocular reflex gain and the corrective saccades in detecting vestibular strokes.

Methods: Prospective cross-sectional study (convenience sample) of patients presenting with acute vestibular syndrome in the emergency department of a tertiary referral centre between February 2015 and May 2020. We screened 1677 patients and enrolled 76 patients fulfilling the inclusion criteria of acute vestibular syndrome. All patients underwent video head impulse test with automated and manual data analysis. A delayed MRI served as a gold standard for vestibular stroke confirmation.

Results: Out of 76 patients, 52 were diagnosed with acute unilateral vestibulopathy and 24 with vestibular strokes. The overall accuracy of detecting stroke with an automated vestibulo-ocular reflex gain was 86.8%, compared to 77.6% for cumulative saccade amplitude and automatic saccade mean peak velocity measured by an expert and 71% for cumulative saccade amplitude and saccade mean peak velocity measured automatically. Gain misclassified 13.1% of the patients as false positive or false negative, manual cumulative saccade amplitude and saccade mean peak velocity 22.3%, and automated cumulative saccade amplitude and saccade mean peak velocity 28.9% respectively.

Conclusions: We found a better accuracy of video head impulse test for the diagnosis of vestibular strokes when using the vestibulo-ocular reflex gain than using saccade metrics. Nevertheless, saccades provide an additional and important information for video head impulse test evaluation. The automated saccade detection algorithm is not yet perfect compared to expert analysis, but it may become a valuable tool for future non-expert video head impulse test evaluations.