We report a case of paroxysmal downbeat nystagmus, ataxia, and dysarthria in the context of a delirium in a patient with severe hypomagnesemia. Extensive workup did not provide alternative explanations. Her attacks subsided within 48 h after the start of magnesium substitution and the patient remained confused and ataxic with a gradual but full recovery over 6 weeks. Hypomagnesemia resulted most probably from long-term proton-pump inhibitor (PPI) intake. Paroxysmal downbeat nystagmus is rare and has so far only been consistently described in association with hypomagnesemia of various causes.

ObjectivesPeripheral vestibular hypofunction (PVH) affects a significant portion of the population and impairs visual acuity during head motion (dynamic visual acuity, DVA). This study compared the effectiveness of a novel gaze stability training called Incremental VOR Adaptation (IVA) versus traditional vestibular physical therapy (VPT) for improving DVA.MethodsThe Incremental Velocity Error as a New Treatment in Vestibular Rehabilitation (INVENT) trial is a randomized, controlled, cross-over study involving 24 participants with chronic unilateral or bilateral PVH. Participants underwent either IVA or VPT for 3 weeks, followed by a washout period and then the alternate intervention (IVA-VPT or VPT-IVA). DVA was measured at baseline, after each intervention, at the completion of the washout period, and at 6-month follow-up.ResultsThere was a significant main effect of treatment Group, (1,19) = 7.75, = 0.012, with (IVA-VPT) consistently demonstrating lower DVA scores than VPT-IVA. A significant main effect of Side was also observed, (1,19) = 13.35, = 0.0017, indicating lower DVA scores for contralesional compared to ipsilesional head rotation. We found no effect of Time ( (4,76) = 1.44, = 0.23), suggesting that scores remained stable from baseline through the 6-months follow-up. There were no significant interactions, including Group × Side ( (1,19) = 0.11, = 0.74), Group × Time ( (4,76) = 1.33, = 0.27), or Group × Side × Time ( (4,76) = 0.59, = 0.67).ConclusionDVA scores were consistently better at all time points after participants completed IVA. Using an intent to treat analysis, with no baseline demographic differences between groups, our data support that exposure to the first gaze stability training type exerts a stable influence on DVA that persisted to 6-month follow-up. Clinically, this implies that once DVA improvements are established through either IVA or VPT, they tend to remain stable over 6 months.Level of EvidenceLevel 2.

ObjectivesKinesiophobia is the condition in which the patient restricts their movements and activities because of the fear of being injured again after a painful experience. Numerous studies have found kinesiophobia in patients with vestibular disorders. This research study aimed to develop and measure the psychometric properties of the Tampa Scale of Kinesiophobia (TSK-11), for use in persons with dizziness (TSKd).MethodsAn observational validation study of questionnaires was carried out including 211 participants with dizziness. After adapting the TSK-11 items to the symptoms of dizziness, the construct validity was evaluated with principal component analysis (PCA), internal consistency with the calculation of Cronbach's alpha, test-retest reliability with the intraclass correlation coefficient (ICC), concurrent validity with Spearman correlation and predictive validity with ROC curve analysis.ResultsThe PCA retained 10 items from the original scale with a three-factor structure that mediates fear (TSKd_f), negative thoughts (TSKd_n) and avoidance (TSKd_a). Cronbach's alpha was 0.810 for the 10-item TSKd. Reproducibility was moderate to substantial, with ICCs between 0.69 and 0.84. The TSK showed strong correlations with the DHI, while correlations with other dizziness measures were moderate. A TSKd score >25 and TSKd_f score >9 showed good predictive capacity, with an area under the curve (AUC) ROC of 0.85 and a sensitivity and specificity between 0.85 and 0.70.ConclusionsThe TSKd is a tool available for measuring kinesiophobia in persons with dizziness. Both the 10-item TSKd and the 4-item TSKd_f scales have good psychometric properties.

BackgroundPeople with vestibular hypofunction (PwVH) often demonstrate abnormal gait and increased fall risk. An analysis of the strategies used for maintaining walking balance is lacking in PwVH.ObjectiveThe purpose of this study was to examine how PwVH use recovery strategies and maintain stability following perturbations.MethodsPwVH and healthy controls were perturbed during walking with mediolateral ground shifts while kinematic responses were recorded.ResultsAs a group, PwVH ( = 9, unilateral loss) responded similarly to healthy participants ( = 15) with changes in foot placement, ankle inversion, ankle push-off, and trunk sway. However, responses in PwVH depended on the vestibular lesion side and functional compensation as assessed by the Functional Gait Assessment (FGA). PwVH had larger changes in stability when perturbations caused body movement toward the side of the lesion and more effective trunk responses when perturbations caused body movement away from the lesion. Additionally, PwVH who performed poorly on the FGA showed worse stability and overactive ankle and trunk responses following medial perturbations.ConclusionsThese findings demonstrate kinematic differences in balance recovery in PwVH and suggest that PwVH are more susceptible to instability when falling toward the lesion.

BackgroundSubjective visual vertical (SVV) test is a key functional assessment tool that provides insights into vestibular imbalance. Mobile virtual reality SVV measurement system (MVR-SVV) has the potential to facilitate simple, low-cost, and reliable measurements.ObjectiveThis study aimed to verify the reliability and validity of MVR-SVV by comparing its data with the previously established bucket test (bucket-SVV).MethodsThirty-eight healthy adults completed both bucket-SVV and MVR-SVV tests. The reliability and validity of MVR-SVV were examined using intraclass correlation coefficients (ICCs), Pearson's correlation, Bland-Altman plots (BAP), and minimum detectable change (MDC).ResultsBAP results indicated that the limits of agreement for the SVV angles were 1.61 to -1.24°. No fixed errors were identified ( = 0.13), although a small proportional error was detected (y = -0.59x + 0.157, < 0.001). Pearson's correlation coefficient between bucket-SVV and MVR-SVV was 0.716 ( < 0.001). Within-day reliability was poor for bucket-SVV, with ICC = 0.33-0.38, but moderate for MVR-SVV, with ICC = 0.70-0.71. Between-day reliability was poor for both methods, with ICC = 0.38 for MVR-SVV and ICC = 0.28 for bucket-SVV. MDC was 1.78° for bucket-SVV and 2.67° for MVR-SVV.ConclusionsOur findings suggest that MVR-SVV can be used for assessing SVV. Its portability, availability, and reliability make it a valuable tool for clinicians in clinical settings.

BackgroundPatients with persistent postural-perceptual dizziness (PPPD) suffer from symptoms of chronic dizziness that exacerbate in a moving environment. However, not much is known regarding gaze behavior in a static condition. The present study investigated gaze stability under static visual stimuli in patients with PPPD.MethodsThree groups of participants were recruited; 22 PPPD, 9 Ménière's disease (MD) and 19 healthy participants (HC). Participants were asked to undergo a free viewing test of emotionally neutral images through a virtual reality headset with a gaze-recording system. Bivariate Contour Ellipse Area (BCEA), a measure for gaze stability, and saliency values at points of gaze fixations were measured.ResultsPPPD showed smaller BCEA compared to MD and HC, with high anxiety state being a possible confounding factor. There was no difference in saliency values between all three groups.ConclusionsPPPD, MD, and HC all tended to fixate on salient parts of the images, but in PPPD, gaze was restricted to a smaller area compared to MD and HC. Considering that previously reported studies on PPPD patients showed gaze instability under dynamic stimuli, the gaze behavior from the present study, involving static stimuli, may reflect the opposite pole to that of dynamic stimuli.

BackgroundSense of direction (SOD) can be affected in patients with vestibular dysfunction.ObjectiveTo record differences in self-perceived sense of direction using the Santa Barbara Sense of Direction scale (SBSOD) in persons with dizziness and balance disorders over time. To determine relationships between self-perceived sense of direction and the Dizziness Handicap Inventory (DHI), Activities-specific Balance Confidence (ABC) scale, and Gait Disorientation Test (GDT).MethodsIn this prospective cohort study, 56 participants completed the SBSOD at three time points: self-recalled SOD before dizziness onset (pre-dizziness), SOD at initial evaluation (SBSOD-Eval), and SOD 3 months post-evaluation (SBSOD-3M). Participants completed DHI, ABC, and GDT at baseline. Repeated measures ANOVA and Spearman's correlation were used for analysis.ResultsMean SBSOD scores were 4.8 (SD ± 1.1) pre-dizziness; 4.6 (SD ± 1.1) at evaluation; and 4.5 (SD ± 1.2) at 3 months. Significant differences were found between pre-dizziness versus evaluation ( = .03) and pre-dizziness versus three months ( = .02). SBSOD-Eval had significant negative correlation with DHI total score (r = -0.3, = .019), significant positive correlation with ABC score (r = 0.4, < .001), and no correlation with GDT.ConclusionsOn average, participants reported that their sense of direction was worse after the onset of dizziness. A better SBSOD was significantly correlated with higher disability levels and better balance confidence.

Mastoid vibration (MV) is a non-invasive way to induce vestibular illusions. However, the influence of MV on gait kinetics during different visual conditions has not been well-established. The purpose of this study was to examine the influence of different types of MV (bilateral vs unilateral) on vertical ground reaction force (vGRF) during walking under both vision-available (VA) and vision-deprived (VD) conditions. Twenty healthy adults walked at their preferred speed on a pressure-sensor treadmill and vGRF characteristics (peak forces, impulses, loading/unloading rates, and variability) were recorded under VA and VD conditions, with and without MV. Vision deprivation increased magnitude and variability of most vGRF variables, suggesting more cautious gait. Bilateral MV (but not unilateral MV) significantly increased the components of vGRF and their variabilities in push-off phase, likely as part of a consistent "press forward" motor response to the vestibular illusion. These results show that MV systematically modulates kinetics, particularly when applied bilaterally and with no visual input. This interaction between vestibular and visual afferents in these young adults may lay a foundation and should be considered in the clinical assessment of gait patterns (GRF profiles) in the future, particularly when using pressure sensor embedded treadmills.

IntroductionThe advent and growth of social media platforms have dramatically altered the landscape of health information sharing, particularly for conditions like Meniere's disease. This study delves into the nature and impact of shared experiences and peer support concerning Meniere's disease on social media, underscoring the critical need for analyzing this content for its influence and accuracy. This study aims to analyze the portrayal of Meniere's disease across social media platforms, focusing on content accuracy and misinformation, to provide vestibular care professionals with insights for improving patient education and fostering more effective patient engagement.Materials and methodsEmploying a comprehensive qualitative approach, our study scrutinized 1108 social media posts about Meniere's disease from Facebook, Instagram, and TikTok-over 3 months. Analysis included authorship identification, examination of the subject matter, tone assessment, and evaluation of post popularity and engagement metrics.Results and analysisA significant portion of the analyzed posts were predominantly image-driven, with a majority authored by patients or their family members. Instagram was the most utilized for Meniere's disease discussions, followed by Facebook and then TikTok. The content analysis revealed that personal experiences comprised 40% of the posts, followed by informational posts, and queries or advice-seeking posts. Sentiment analysis showcased a diverse range of emotions: 45% of posts displayed a positive tone, 35% were neutral, and 20% expressed negative sentiments.DiscussionThe findings from this study highlight a significant demand for accurate and authoritative educational resources on social media regarding Meniere's disease. They offer vestibular care providers, including otolaryngologists, audiologists, physical therapists, speech-language pathologists, and others valuable insights into improving patient-centered care by developing and implementing effective communication strategies. Emphasizing patient empowerment, these strategies should cater to a patient population that is increasingly turning to social media for health-related information. The study also points to the necessity of addressing misinformation and guiding patients towards reliable sources of medical information online.

Dizziness significantly impairs health-related quality of life, yet its specific impact remains underexplored. Gaining insight into this relationship is essential for providing optimal care. Thus, this study aimed to explore the impact of dizziness-related quality of life (DRQOL) and develop a conceptual framework to inform patient-centered care. Participants with documented complaints of dizziness, vertigo, or unsteadiness were identified via medical record review. Those with severe medical illness or disability were excluded. 30 adults (12 males and 18 females), diagnosed with vestibular (n = 10), neurological (n = 10), or nonspecific-related dizziness (n = 10) were recruited. Semi-structured interviews were conducted using Zoom to examine the effects of dizziness on daily life. Interviews were transcribed, de-identified, and analyzed using thematic content analysis. Findings revealed that dizziness and imbalance affect multiple domains, including physical health (functioning, symptoms, and vision), social health (impact and support), cognitive health, and mental health (both positive and negative). These impacts were consistent across all diagnostic subgroups. Despite challenges, many participants reported adaptive responses, including coping strategies and resilience. The study highlights the broad and debilitating effects of dizziness, while also recognizing the role of positive outcomes.

The illusion of self-motion provoked by dynamic visual stimulation is known as vection and is a common phenomenon when using visual displays such as virtual reality, video games, or movie theatres. Vection has been historically linked to visually induced motion sickness (VIMS), a phenomenon similar to traditional motion sickness characterized by various symptoms including nausea, fatigue, or eyestrain. Many factors are associated with an individual's susceptibility to VIMS and vection, but their impact is not well understood. Here, we investigated how field dependence, biological sex, and age are linked to the occurrence of VIMS and vection. To achieve this, we combined the datasets from four independent experimental studies with a pooled sample size of N = 336, including 237 younger and 99 older adults. Our results demonstrated that younger adults experienced significantly more VIMS compared to older adults and that women reported more VIMS than men (although this effect was rather weak). Additionally, field dependence was positively correlated with vection in younger adults, but no relationship between field dependence and VIMS was found. Overall, the findings from this study suggest that field dependence is not a relevant factor related to VIMS. Interestingly, older adults seem to be at lower risk of experiencing VIMS, which is encouraging considering that many novel applications are tailored towards an ageing population for rehabilitation or training purposes.

BackgroundVestibular evoked myogenic potentials (VEMPs) are widely used to assess the otolith organs; however, the clinical significance of otolith organ dysfunction is unclear.ObjectiveThe primary purpose was to determine the functional consequences of otolith dysfunction on postural stability and quality of life in U.S. Veterans.MethodsA prospective case-control design was used, and 124 participants (21-84 years) were grouped based on comprehensive vestibular testing. Caloric and vertical canal video head impulse testing were used to determine semicircular canal function. Cervical and ocular VEMP testing determined otolith organ function. Three vestibular site-of-lesion groups (Otolith Only, Otolith + Canal, and Canal Only) and two control groups (Dizzy Control and Non-Dizzy Control) completed measures of quality of life and multiple measures of postural control.ResultsANCOVAs indicated significant group differences for measures of quality of life and postural stability. All vestibular groups (Otolith Only, Otolith + Canal, and Canal Only) reported significantly worse quality of life than Non-Dizzy Controls. The Otolith + Canal group performed significantly worse than the Otolith Only group and both control groups on the functional gait assessment and preferred gait speed.ConclusionsSimilar to isolated semicircular canal dysfunction, isolated otolith dysfunction may negatively impact quality of life, and in conjunction with semicircular canal dysfunction, may also negatively impact postural stability.

BackgroundDespite the role attributed to cervical proprioception in balance control, the impact of cervical dysfunction on patients with dizziness remains largely elusive.ObjectiveTo investigate the effects of cervical abnormalities on the quality of life and balance control of patients with unilateral peripheral vestibulopathy.MethodsThis was an observational cross-sectional study. Sixty-one patients with dizziness of peripheral origin were enrolled. They filled out clinical questionnaires, the Dizziness Handicap Inventory (DHI), and the Neck Disability Index (NDI). Twenty-four individuals without vestibular or neck complaints were used as controls. The participants underwent the Cervical Joint Position Error Test (CJPT) and a static posturography.ResultsPatients with dizziness showed worse CJPT results (p = 0.0003). During conditions 1 and 3 of posturography, patients with cervical symptoms performed particularly worse compared to those without them. Also, their mean DHI was higher ( = 0.014). DHI and the CJPT results correlated in the case group (r = 0.32; p = 0.012). In the subgroup with cervical complaints, the NDI and DHI scores showed a moderate correlation (r = 0.540; = 0.0001).ConclusionCervical proprioception correlated with the DHI scores in patients with dizziness. Patients with vestibular disorders with cervical complaints showed poorer results in balance control. Among them, the scores of self-perceived handicap of cervical complaints and dizziness correlated.

BackgroundDizziness is an unpleasant symptom which can cause anxiety and fear of movement (kinesiophobia) which may lead to avoidance of physical activity. There are no reliable and valid questionnaires available to detect kinesiophobia in patients with peripheral vestibular dizziness.ObjectiveTo adapt the Tampa Scale for Kinesiophobia (TSK-SV) to TSK-SV Dizziness and to investigate the questionnaire´s reliability and validity.MethodsThe TSK-SV was adapted to TSK-SV Dizziness in patients with peripheral vestibular disorder. Test-retest reliability and internal consistency was calculated. Face and content validity construct and a confirmatory factor analysis were performed. Concurrent validity was assessed in relation to Hospital anxiety and depression scale (HADS-A, HADS-D), Dizziness Handicap Inventory (DHI), Short form-36, Self-reported physical activity, assessment of dynamic and static balance function.ResultsTSK-SV dizziness showed excellent test-retest reliability (intraclass correlation coefficient 0.91) and excellent internal consistentcy (Cronbach's alpha 0.76). Confirmatory factor analysis provided acceptable model fit for the modified second-order factor model. In concurrent validity moderate to large associations between TSK-SV dizziness, HADS-A, HADS-D and DHI total sum.ConclusionsThis study supports the reliability and validity of the TSK-SV dizziness questionnaire for clinical use in patients with peripheral vestibular dizziness.

ObjectiveTo explore the incidence, risk factors, and comorbidities of persistent postural-perceptual dizziness (PPPD) after stroke.MethodsPatients with acute stroke and vestibular symptoms were enrolled prospectively and continuously. Baseline information, risk factors, imaging materials, and diagnosis were collected. PPPD, anxiety, depression, and quality of life were followed up in 6 months after stroke. Binary logistic regression was used to identify the risk factors of PPPD.ResultsIn this study, 284 patients (82.0% of males) were enrolled, with a mean age of 56.33 ± 11.87 years. Thirty-five patients (12.3%) had PPPD in 6-month follow-up. Patients with PPPD had a higher proportion of clinically significant anxiety and clinically significant depression and a lower three-level five-dimension EuroQol (EQ-5D-3L) index. Binary logistic regression analysis identified medulla oblongata stroke (OR, 5.549; < .001), cerebellar stroke in posterior inferior cerebellar artery (PICA) territory (OR, 2.449; = .026), and clinically significant anxiety at discharge (OR, 5.030; < .001) were significant predictors for PPPD.ConclusionsAbout 12.3% of stroke patients with vestibular symptoms developed PPPD at 6 months after stroke, with a higher prevalence of psychological comorbidities and decreased quality of life. Medulla oblongata lesion, cerebellar (PICA territory) lesion, and clinically significant anxiety at discharge were independent risk factors for PPPD.

BackgroundThe vestibular system is essential for balance and visual stability and relies on the ocular counter-roll (OCR) reflex to regulate torsional eye movements during head tilt.ObjectiveThis study aimed to investigate how different tilt angles (15° and 45°) and tilt positions (head and body) influence static video Ocular Counter-Rolling (vOCR) responses in healthy individuals.MethodsA total of 30 healthy volunteers (17 females and 13 males), aged between 18 and 30 years, participated in the study. vOCR testing was conducted using the Interacoustics VisualEyes™ 525 video-oculography (VOG) system. Torsional eye movements were recorded at 15° and 45° during both lateral head tilt and body block tilt. Torsion degree, asymmetry, and gain values were analyzed and compared across all conditions.ResultsGain values did not significantly differ based on tilt angle or position (p > 0.05). The degree of torsional eye movement was significantly higher at 45° tilts compared to 15°, and greater during body tilt than head tilt (p < 0.0001). Asymmetry values remained within normal limits under all conditions and showed no significant differences (p > 0.05).ConclusionsThese findings indicate that the angle and position of tilt affect the magnitude of the rotational response, but that gain and asymmetry values remain consistent across conditions. This suggests that comparable gains can be obtained at different angles, such as 15° and 45°, and that low-angle tilts may be sufficient for evaluating otolith-ocular gain.

BackgroundCerebellopontine angle (CPA) tumors commonly cause audiovestibular symptoms due to eighth cranial nerve involvement. While vestibular schwannoma (VS) is the most frequently observed CPA tumor, vestibular outcomes following surgery for non-VS CPA tumors remain underreported.ObjectivesTo compare post-operative vestibular function, as assessed by the video Head Impulse Test (vHIT), between patients with VS and non-VS CPA tumors.MethodsA retrospective review was conducted on 37 patients (23 VS, 14 non-VS) who underwent CPA tumor resection and had vHIT evaluations pre- and post-operatively. Changes in vestibulo-ocular reflex (VOR) gain across the three semicircular canals were analyzed at 1 and 6 months after surgery.ResultsAlthough pre-operative VOR gains were comparable, the non-VS group demonstrated significantly better VOR gain recovery at 6 months in the horizontal and posterior semicircular canals (p = 0.0055, p = 0.0019, respectively). Notably, VOR gains in these canals improved beyond pre-operative levels in the non-VS group. No significant improvement was observed in the anterior semicircular canal.ConclusionsvHIT outcomes indicate more favorable spontaneous vestibular recovery in non-VS CPA tumor than in VS tumor patients. These findings emphasize the importance of vestibular nerve preservation during non-VS tumor surgery and suggest differences in neural involvement between tumor types.

BackgroundPersistent postural-perceptual dizziness (PPPD) is a common yet challenging functional vestibular disorder. The Niigata PPPD Questionnaire (NPQ) is a simple diagnostic tool developed to assess the severity and presence of PPPD.ObjectiveTo validate the Korean version of the NPQ and to evaluate its reliability and diagnostic performance in differentiating PPPD from other vestibular disorders in comparison to Dizziness Handicap Inventory (DHI).MethodsWe recruited 255 patients, 150 with PPPD, 64 with peripheral vestibular disorders, and 41 with central vestibulopathy at a tertiary dizziness center in South Korea from January to December 2024. The NPQ was translated into Korean with a forward-backward translation procedure. In addition, all participants completed DHI, the Beck Depression Inventory-II (BDI-II), the State-Trait Anxiety Inventory (STAI), and the Perceived Stress Scale (PSS) to assess dizziness-related disability and psychological symptoms. Internal consistency was assessed using Cronbach's alpha. Discriminative ability was evaluated through between-group comparisons, correlation analyses, and receiver operating characteristic (ROC) curve analyses.ResultsThe Korean NPQ demonstrated excellent internal consistency (Cronbach's α = 0.93). The total and subscale scores of the NPQ were significantly higher in PPPD than in other vestibular disorder groups. ROC analysis yielded an area under the curve of 0.670 with a cut-off score at 15.5 (sensitivity 59.3%, specificity 71.4%). The visual stimulation subscale showed the highest AUC (0.703). A logistic regression combined model using NPQ visual stimulation and dizziness handicap inventory (DHI) emotional subscales achieved the best diagnostic accuracy (AUC = 0.756). The NPQ total score was moderately correlated with the DHI (ρ = 0.65) and modestly correlated with psychological symptoms.ConclusionThe Korean NPQ is reliable and provides acceptable diagnostic utility for distinguishing PPPD. Combining NPQ and DHI subscales enhances diagnostic accuracy, supporting its use as a screening tool in diverse clinical settings, including telemedicine.

BackgroundMotion sickness (MS) occurs when the brain receives conflicting signals about body movement from the visual, vestibular, and proprioceptive systems. The otolith organs play a key role in perceiving verticality, and their function may be influenced by MS susceptibility.ObjectiveThis study aimed to investigate the effect of MS susceptibility on otolith-mediated verticality perception across different head positions.MethodsForty-seven participants were classified into two groups based on the Motion Sickness Susceptibility Questionnaire-Short Form (MSSQ-SF): an MS group (n = 24) and a control group (n = 23). All participants completed static Subjective Visual Vertical (SVV), dynamic Subjective Visual Vertical (DVV), and Rod-and-Frame Test (RFT) using a virtual reality system. Measurements were conducted in three head tilt (upright, 30° left, 30° right). The absolute deviation from true vertical was calculated for each test.ResultsWhile no significant differences were found in SVV performance between groups across head-tilt angles, the MS group exhibited significantly greater deviations in DVV at all positions and in RFT during 30° head tilts. Higher MSSQ scores correlated with greater deviations in DVV and RFT under tilt conditions.ConclusionsAlthough static verticality perception remains intact, individuals with MS exhibit greater deviations under dynamic and visually misleading conditions, suggesting subtle vestibular-perceptual deficits.

PurposeTo estimate the prevalence of endolymphatic sac hypoplasia (EShp)-a proposed specific finding in Ménière's disease (MD) that defines an endophenotype characterized by bilateral involvement, male predominance, temporal bone abnormalities, and familial clustering-in individuals without MD, to assess its specificity for the condition.MethodsWe analyzed 956 temporal bone CT scans from individuals without MD to assess the prevalence of EShp using the Angular Trajectory of the Vestibular Aqueduct (ATVA) marker. ATVA distribution, reproducibility, and associations with clinical variables were also evaluated.ResultsEShp was identified in 6 ears from 4 individuals, yielding a prevalence of 0.6% per patient and 0.8% per ear. ATVA values had a median of 95.0° (IQR = 12.5°, range 65.9°-159.4°). Interobserver agreement was good (ICC = 0.75), with a mean bias of 6.2° ± 5.4° and 5.5% of ears outside the 95% limits of agreement. No significant associations were found between ATVA and sex, age, or clinical diagnosis.ConclusionsEShp is rare in individuals without MD, supporting its specificity and potential role in MD pathophysiology. The ATVA marker is reliable and reproducible and may serve as a CT biomarker for the hypoplastic MD endophenotype.

ObjectiveThe study aims to assess the high-frequency Vestibulo-Ocular Reflex (VOR) gain across three pairs of semicircular canals using the EyeSeeCam device and to determine normative values.MethodsA total of 105 volunteers, aged 19 to 69 years with no history of vestibular disorders, were enrolled. This cohort included 50 males (mean age 41.11 ± 15.98) and 55 females (mean age 35.52 ± 15.07), with no statistically significant age difference between the genders ( = 0.078). Participants were categorized into six age brackets: 11-20, 21-30, 31-40, 41-50, 51-60, and 61-70. For each test, the recording device was consistently positioned on the left side of the goggles, and the tests were conducted by a right-handed operator.ResultsThe average regression gain for left anterior-right posterior canals (LARP) was 1.44 ± 0.19, significantly surpassing that of right anterior-left posterior canals (RALP) at 1.09 ± 0.13 ( < 0.001) and horizontal semicircular canals (HSC) at 1.11 ± 0.07 ( < 0.001). No significant difference was observed between the VOR gains of RALP and HSC ( = 0.1077). Additionally, VOR gain values did not show significant variation across different age groups. In a gender-based analysis, a marginally higher HSC gain was observed in females (1.13 ± 0.07) compared to males (1.11 ± 0.07; = 0.042), while no significant gender disparity was noted for RALP gains (females: 1.09 ± 0.11; males: 1.10 ± 0.14; = 0.641). Females exhibited significantly higher LARP gain values (1.49 ± 0.18) than males (1.41 ± 0.20; = 0.002).ConclusionThis study underscores the stability of high-frequency VOR gain values across ages. However, it also reveals a significant asymmetry in vertical canal gains (LARP vs RALP), suggesting a possible vertical canals monocular directional preponderance. This finding highlights that normative values can be highly specific to the recording and testing protocol. Thus, laboratories should develop their own normative values, customized to their equipment and testing protocols.