Assessment of Otolith Function with Subjective Visual Vertical Test in Sensorineural Hearing Loss: An Analytical Cross - Sectional Study.

The inner ear is responsible for balance and auditory function. Sensorineural hearing loss (SNHL) affects auditory function across various age groups. Vestibular apparatus, particularly the otolith organ can also be affected in cases of SNHL because of the close proximity of the otolith organs with the cochlea inside the bony labyrinth. The otolith organs can be assessed with Subjective Visual vertical test (SVV), which is a simple, rapid, non-invasive test with high sensitivity and specificity. Present study was conducted with the objective to compare the SVV parameters between normal and SNHL patients and to correlate between the degree of tilt in SVV with severity of SNHL. A convenient sample size of 60 was taken of which 30 were control and 30 were SNHL patients. PTA and SVV were performed on both groups and results were analysed in IBM SPSS version 26. Age stratified analysis between the control group and SNHL group for the age group 20-40 years and for > 40 years revealed a significant statistical difference in the average static SVV (P = 0.019 and P = 0.009 for age group 20-40 years and > 40 years respectively) and dynamic anti clockwise SVV (P = 0.024 and P = 0.031 for age group 20-40 years, and > 40 years respectively) between the control group and the SNHL group. Correlational analysis also shows a moderate correlation between the bone conduction threshold and the various SVV parameters. Statistical difference of SVV parameters between the two groups suggests a possible early involvement of the otolith organ in SNHL. As such the utility of SVV as an early marker for otolith dysfunction needs to be further explored. It may be worthwhile to follow up the patients of SNHL longitudinally and assess the otolith function with SVV at periodic intervals to identify any progression.

Subjective visual vertical/horizontal and video head impulse test in dyslexic children.

Different studies have tried to establish a relationship between dyslexia and the vestibular system function. Subjective Visual Vertical/Horizontal (SVV and SVH) and Video Head Impulse Test (VHIT) are useful for studying the vestibular system and can be easily performed in children. Our aim was to evaluate the vestibular function in dyslexic children by SVV/SVH and VHIT. We enrolled 18 dyslexic children (10M/8F; mean age 10.7 ± 2.3 years; range 7-14 years) and 18 age-matched children with typical development of learning abilities. All children performed VHIT, SVV and SVH. We found normal gain and symmetry of vestibulo-ocular-reflex both in dyslexic and typically developing children. Fifteen out of 18 dyslexic children (83.3%) showed a difference of at least one amongst SVV or SVH. The mean value of SVV was 2.3° and the mean value of SVH was 2.6°. Statistical analysis showed a significant difference between typically developing and dyslexic children for both SVV and SVH. We confirm a relationship between dyslexia and the alteration of SVV and SVH. Our results could be related to the pathogenetic hypothesis of a visual processing impairment related to a dysfunction of the magnocellular pathway or to a general deficit related to a multimodal cortical network.

[Test-retest reliability of subjective visual vertical from different head-tilt angles in young healthy adults].

Objective:To establish the normal values of subjective visual vertical （SVV） in different head deflection angles and analyze its test and retest reliability, in order to provide a reference for the clinical application of SVV in the evaluation of vestibular disorders. Methods:Thirty-one healthy young people were selected to wear VR glasses, and the SVV data were tested in five different head-tilt, namely, 0° in the upright head position, 45°in the left head position, 45° in the right head position, 90° in the left head position, and 90° in the right head position, and were re-tested 2 weeks later. Results:①The mean values of SVV at 5 different head-tilt angles of 0°, left 45°, right 45°, left 90°, and right 90° were -0.07±1.71, 4.30±5.39, -6.51±5.58, -3.76±7.42, and 0.40±8.02, respectively, The 95% confidence limits of SVV at 0°, left 45°, right 45°, left 90°, right 90°, and right 90° were （-3.42, 3.28）, （-6.26, 14.86）, （-17.45, 4.43）, （-18.30, 10.78）, and（-15.32, 16.12）, respectively; ②The absolute values of SVV at 4 different head-tilt angles of left 45°, right 45°, left 90°, and right 90° were 5.62±3.96, 6.90±5.07, 6.82±4.70 and 6.48±4.68, respectively. The 95% confidence limits of SVV at left 45°, right 45°, left 90°, right 90°, and right 90° were（0，12.11）,（0，15.21）,（0，14.53）and（0，14.16）, respectively. The asymmetry ratio is 10% for the absolute value of the 45 ° deviation and 3% for the absolute value of the 90° deviation; ③Intra-class correlation coefficients（ICC） for 0°, left 45°, right 45°, left 90°, right 90°were 0.757, 0.673, 0.674, 0.815, and 0.856, respectively. Conclusion:SVV has good retest reliability and high stability, and the SVV normal value data of different head deviation angles established in the present study can be used as a reference for the diagnosis and evaluation of vestibular disorders.

Asymmetry of the Subjective Visual Vertical in Patients With Unilateral Peripheral Vestibular Deficit.

BACKGROUND AND OBJECTIVES: Perception of verticality is clinically assessed using the subjective visual vertical (SVV), a test of the otolith system that consists of aligning a bar on the gravitational vertical in darkness. Patients with acute unilateral vestibulopathy (AUVP) show a systematic SVV bias toward the affected side, whichever the side of line orientation. Whether SVV estimates are symmetrical has not been investigated. SUBJECTS AND METHODS: This study included 10 patients with AUVP (vestibular neuritis) and 10 with BPPV (posterior semicircular canal). SVV measurements were made at two preset angles of line orientation (15° and 30°) toward the ipsilateral and contralateral sides, relative to the affected side. RESULTS: The results showed asymmetrical SVV estimates in the AUVP group, with significantly greater SVV errors for ipsilateral than contralateral line orientation, as well as for the preset angle of 30° compared to 15°. SVV estimates were significantly lower in patients with BPPV who also exhibited SVV asymmetry. SVV estimates remained unchanged just after the maneuver and were normalized some days later or after supplementary maneuvers. CONCLUSIONS: SVV asymmetry should be routinely considered in the clinic. We recommend individually assessing ipsilateral and contralateral SVV and using at least two preset angles. This allows for a better assessment and diagnosis of otolith organ imbalance that can trigger chronic instability and dizziness. The contribution of neck afferents related to head position in space seems to be the main source of SVV asymmetry.

Clinical Assessment of Subjective Visual and Haptic Vertical Norms in Healthy Adults.

BACKGROUND AND OBJECTIVE: Accurate verticality perception is essential for daily life activities, such as correctly estimating object orientation in space. This study established normative data for the subjective visual vertical (SVV) and subjective haptic vertical (SHV) using the portable and self-constructable modified Bucket test and Rotating-Column test. Additionally, the contribution of age, sex, and starting position of the line/ column on SVV and SHV accuracy were evaluated. METHOD: This study, part of the PRECISE project (ClinicalTrials.gov ID NCT05978596), was conducted following the STROBE guidelines. Healthy adults without visual/neurological/vestibular disorders were recruited. Subjective visual vertical and SHV accuracy were described in terms of constant errors (i.e., mean deviation from 0° [true vertical] respecting its direction), unsigned errors (i.e., mean deviation from 0° irrespective of direction), and variability (i.e., intra-individual standard deviation). RESULTS: Sixty participants were evaluated (mean age: 41.14 [SD = 16.74] years). Subjective visual vertical constant errors between -2.82° and 2.90°, unsigned errors up to 2.15°, and variability up to 1.61° are considered normal. Subjective haptic vertical constant errors ranged from -6.94° to 8.18°, unsigned errors up to 6.66° and variability up to 4.25°. Higher ages led to higher SVV unsigned errors and variability. SHV variability was higher in females compared to males. Certain starting positions led to higher SVV and SHV constants and SVV unsigned errors. DISCUSSION: Normative data are provided for affordable, self-constructable, and portable SVV and SHV tools. These norms are consistent with more sophisticated equipment and can be used to distinguish between normal and abnormal values.

Comparison of postural control and space perception outcomes between robotic and conventional cochlear implantation in adults.

PURPOSE: The aim of the study is to capture the difference between the groups in direct relation to the type of electrode array insertion during cochlear implantation (CI). The robotic insertion is expected to be a more gently option. As recent studies have shown, there is a difference in perception of visual vertical (SVV) and postural control related to the CI. We assume that there can be differences in postural control and space perception outcomes depending on the type of the surgical method. METHODS: In total, 37 (24 females, mean age ± SD was 42.9 ± 13.0) candidates for CI underwent an assessment. In 14 cases, the insertion of the electrode array was performed by a robotic system (RobOtol, Colin, France) and 23 were performed conventionally. In all of these patients, we performed the same examination before the surgery, the first day, and 3 weeks after the surgery. The protocol consists of static posturography and perception of visual vertical. RESULTS: The both groups, RobOtol and conventional, responded to the procedure similarly despite the dissimilar electrode insertion. There was no difference between two groups in the dynamic of perception SVV and postural parameters. Patients in both groups were statistically significantly affected by the surgical procedure, SVV deviation appeared in the opposite direction from the implanted ear: 0.90° ± 1.25; - 1.67° ± 3.05 and - 0.19° ± 1.78 PRE and POST surgery (p < 0.001). And this deviation was spontaneously adjusted in FOLLOW-UP after 3 weeks (p < 0.01) in the both groups. We did not find a significant difference in postural parameters between the RobOtol and conventional group, even over time. CONCLUSION: Although the robotic system RobOtol allows a substantial reduction in the speed of insertion of the electrode array into the inner ear, our data did not demonstrate a postoperative effect on vestibular functions (SVV and posturography), which have the same character and dynamics as in the group with standard manual insertion. REGISTRATION NUMBER: The project is registered on clinicaltrials.gov (registration number: NCT05547113).

Assessments of Subjective Visual Gravity and Spontaneous Nystagmus in Patients With Vestibular Neuritis.

OBJECTIVE: This study aimed to assess the correlation between the spontaneous nystagmus (SN) and the subjective visual vertical/horizontal (SVV/SVH) among patients with vestibular neuritis (VN) at the different head positions. STUDY DESIGN: Case-control study. SETTING: Affiliated Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine. METHODS: This study evaluated the SVV/SVH in both healthy subjects and patients with VN. These evaluations were performed in 5 different head positions: upright, 45° tilt to the left, 90° tilt to the left, 45° tilt to the right, and 90° tilt to the right. Additionally, the intensity of SN, as measured by slow-phase velocity, was recorded. RESULTS: In patients with VN, a significant correlation was observed between SN and SVV/SVH in an upright position. The intensity of SN was higher when the head was tilted 90° toward the affected side compared to other positions. The SVV/SVH displayed an ipsiversive shift, when the head was tilted toward both the lesion and unaffected sides, exhibiting a contraversive direction. Furthermore, the changes in position-induced SN were consistent with the displacements of SVV and SVH caused by head tilt. CONCLUSION: The presence of SN in patients with VN was observed to vary across different head position. These variations could potentially be attributed to the diverse activation patterns of the mechanical properties of otolith organs that are induced by head tilts.

Visual vertigo and motion sickness is different between persistent postural-perceptual dizziness and vestibular migraine.

INTRODUCTION: Persistent postural-perceptual dizziness (PPPD) and vestibular migraine (VM) share symptoms of visual vertigo and motion sickness that can be confusing for clinicians to distinguish. We compare the severity of these symptoms and dynamic subjective visual vertical (dSVV) in these two common vestibular conditions. METHOD: Twenty-nine patients with PPPD, 37 with VM, and 29 controls were surveyed for subjective symptoms using the visual vertigo analogue scale (VVAS) and motion sickness susceptibility questionnaire during childhood (MSA) and the past 10 years (MSB). dSVV is a measure of visual dependence measures perception of verticality against a rotating background (5 deg./s). RESULTS: VVAS revealed contextual differences for dizziness between those with PPPD and VM. Ratings of visual vertigo were most severe in PPPD, less in VM, and mild in controls (VVAS PPPD 27.1, VM 11.2, control 4.6, p < 0.001). MSA was more severe in VM than in PPPD or control (12.8 vs 7.6 vs 8.5, p = 0.01). MSB was more severe in VM than controls (MSB score 12.9 VS 8.1 p = 0.009) but was not different than PPPD (MSB score 10.0, p = 0.10). dSVV alignment was similar among the three groups (p = 0.83). Both VM and PPPD groups had greater simulator sickness than controls after completing the dSVV. CONCLUSIONS: Patients with PPPD report more visual vertigo than those with VM, but a history of motion sickness as a child is more common in VM. Additionally, the environmental context that induces visual vertigo is different between PPPD and VM.

Effect of drilling on otolithic organ functions in mastoidectomy.

OBJECTIVE: This study aimed to assess the effect of drilling during mastoidectomy on otolithic organ functions and development of benign paroxysmal positional vertigo using objective vestibular tests. MATERIALS AND METHODS: The study included 45 adult patients diagnosed with chronic otitis media who underwent mastoidectomy with drilling. Pre-operative and post-operative assessments included tests for subjective visual vertical deviation and videonystagmography. RESULTS: Subjective visual vertical deviation was significantly higher in post-operative periods. On the third day, the subjective visual vertical deviation was at its maximum (1.4 degrees). Post-operatively, benign paroxysmal positional vertigo was detected in 14 patients (31.1 per cent). The most common type was ipsilateral lateral canal benign paroxysmal positional vertigo (57.1 per cent). CONCLUSION: The effect of drilling on otolithic organ functions in mastoidectomy seems to be temporary and subclinical; however, it potentially could be a risk factor for the development of benign paroxysmal positional vertigo.

Gravity-Dependent Modulation of Downbeat Nystagmus and Subjective Visual Vertical in the Roll Plane.

Downbeat nystagmus (DBN) is the most common form of acquired central vestibular nystagmus. Gravity perception in patients with DBN has previously been investigated by means of subjective visual straight ahead (SVA) and subjective visual vertical (SVV) in the pitch and roll planes only during whole-body tilts. To our knowledge, the effect of head tilt in the roll plane on the SVV and on DBN has not yet been systematically studied in patients. In this study, we investigated static and dynamic graviceptive function in the roll-plane in patients with DBN (patients) and healthy-controls (controls) by assessment of the Subjective Visual Vertical (SVV) and the modulation of slow-phase-velocity (SPV) of DBN. SPV of DBN and SVV were tested at different head-on trunk-tilt positions in the roll-plane (0°,30° clockwise (cw) and 30° counterclockwise (ccw)) in 26 patients suffering from DBN and 13 controls. In patients, SPV of DBN did not show significant modulations at different head-tilt angles in the roll-plane. SVV ratings did not differ significantly between DBN patients vs. controls, however patients with DBN exhibited a higher variability in mean SVV estimates than controls. Our results show that the DBN does not exhibit any modulation in the roll-plane, in contrast to the pitch-plane. Furthermore, patients with DBN show a higher uncertainty in the perception of verticality in the roll-plane in form of a higher variability of responses.

Evaluation of subjective visual vertical and horizontal in patients with acoustic neuroma based on virtual reality.

Objective: To investigate potential differences in absolute deviation values of subjective visual vertical and horizontal between unilateral acoustic neuroma patients and healthy young adults under varying degrees of static head tilt, as well as the impact of proprioception on these values, with the aim of determining the effect of acoustic neuroma on gravity sensory pathway function in patients. Methods: We recruited 22 patients diagnosed with unilateral acoustic neuroma and 25 healthy young adults and employed virtual reality technology to assess the absolute deviation values of subjective visual vertical (SVV) and subjective visual horizontal (SVH) under eight different static tilted head positions (Head centered (0° tilt), PdP, Head tilt 15°, 30°, 45° to the left and right), then compare and analyze intergroup differences. Results: In the Head-centered position, both SVV and SVH absolute deviated values were significantly higher in the AN group compared to healthy young adults. The AN group exhibited significantly higher absolute deviation values of SVV compared to the healthy group when tilting their head 30° left and right. Additionally, when tilting their heads to the right at 15° and 45° the AN group showed significant increases in SVH absolute deviated values compared to healthy adults. The SVV and SVH absolute deviation values of LAN and SAN groups did not reach statistical significance. The results of the SVV test for PDP position did not show any significant differences among all groups. However, the SVH test revealed that the absolute deviation values of the LAN group was significantly higher than that of healthy individuals. Conclusion: Our study shows that the gravity sensing function of patients with unilateral acoustic neuroma is affected to different degrees, however, the degree of gravity sensing function damage of patients has little relationship with tumor size. When acoustic neuroma is larger than 2 cm, the effect of proprioception on patients' SVH outcome is noteworthy. So, we should pay attention to the postoperative follow-up of patients with acoustic neuroma and the evaluation of vestibular rehabilitation effect. Meanwhile, for patients opting for conservative treatment, it is imperative to monitor the dynamic changes in vestibular function and seize timely opportunities for intervention.

Perception of verticality in the post-COVID-19 condition correlates to infection severity.

Background: SARS-CoV-2 infection affects multiple systems, including musculoskeletal, neurological, and respiratory systems. Changes associated with physical inactivity due to prolonged hospitalization can affect the functional capacity of individuals with long coronavirus disease 2019 (COVID-19) or post-COVID-19 condition and may cause changes in some postural control functions, such as verticality. Objectives: This study aimed to evaluate the perception of verticality in individuals with long COVID. Design: Cross-sectional study. Methods: This study included 60 participants with post-COVID-19 condition divided into 2 groups: hospitalized group (n = 24), those hospitalized owing to SARS-CoV-2 infection; and non-hospitalized group (n = 36), those infected with SARS-CoV-2 but not hospitalized. All participants were examined using a post-COVID-19 functional status (PCFS), sit-to-stand test, grip strength assessment, painful and tactile sensory assessments, visual acuity assessment, and vestibular assessment. Verticality perception was evaluated using the subjective visual vertical (SVV) and subjective haptic vertical (SHV) tests. In both tests, the absolute values (positive values only) and true values (positive and negative values) were considered. To verify potential confounders that could influence the verticality of the results, logistic regression models were used for categorical variables and multiple linear regressions were used for continuous variables. For analysis between groups, the independent samples test (Mann-Whitney U test) was used. Results: There were no confounders between clinical variables and verticality in either group. There was a significant increase in absolute SVV (mean deviation [MD]: 2.83; P < .0001) and true SVV (MD: -4.18; P = .005) in the hospitalized group compared to the non-hospitalized group. Furthermore, there was a significant increase in the true SHV (MD: -3.6; P = .026) in the hospitalized group compared to that in the non-hospitalized group. Conclusion: Less accurate visual and haptic verticality perception task performance was observed in hospitalized patients with post-COVID-19 condition.

Modification of cortical electrical activity in stroke survivors with abnormal subjective visual vertical: An eLORETA study.

Objectives: Balance impairment is among the main complications of stroke. The gravity-based subjective vertical (SV) is considered an important reference for upright posture and navigation affected by stroke. The correlation between injury location and pathological perception of verticality remains controversial. This study aimed to evaluate the cortico-cortical network of vertical perception among patients with the right hemisphere stroke and abnormal visual-vertical perception compared with healthy individuals. Materials and methods: This observational cross-sectional study included 40 patients with the right hemisphere stroke and 35 healthy participants. All patients had abnormal visual-vertical perception. The EEG connectivity analysis was conducted through the exact low-resolution brain electromagnetic tomography analysis (eLORETA). Results: Stroke survivors manifested a power spectral density that reduced within the beta-2 frequency band in the left hemisphere and increased within the beta-3 frequency band in the right hemisphere compared with controls (p < 0.01). The lagged-phase synchronization was increased within alpha-1, beta-2, and beta-3 bands and decreased in stroke survivors compared with controls in the vestibular network involved in visual-vertical perception (p < 0.01). Conclusion: The results of this study demonstrated variations in the function and functional connectivity of cortical areas involved in the visual-vertical perception that are mainly located in the vestibular cortex.

Primary Graviceptive System and Astasia: A Case Report and Literature Review.

Astasia refers to the inability to maintain upright posture during standing, despite having full motor strength. Impairment of the vestibulocerebellar pathway, graviceptive system, and cingulate motor area have been proposed to be related to astasia. However, the responsible neural pathways remain unclear. We hypothesize that there is a common neural network behind astasia. To test the hypothesis, we reviewed all reported cases with astasia, including ours, and focused on the correlation between anatomical destruction and symptom presentation. A total of 26, including ours, non-psychogenic astasia patients were identified in the English literature. Seventy-three percent of them were associated with other neurologic symptoms and sixty-two percent of reported lesions were on the right side. Contralateral lateropulsion was very common, followed by retropulsion, when describing astasia. Infarction (54%) was the most reported cause. The thalamus (65%) was the most reported location. Infarctions were the fastest to recover (mean: 10.6 days), while lesions at the brainstem needed a longer time (mean: 61.6 days). By combining the character of lateropulsion in astasia and the presentation of an interrupted graviceptive system, we concluded that the primary graviceptive system may be the common neural network behind astasia. Future studies on astasia should focus on the pathological changes in the perception of verticality in the visual world and the body.

Differential effects of gender and age on dynamic subjective visual vertical.

In a retrospective study, the data of direction-dependent deviations in dynamic subjective visual vertical (SVV) testing were analysed in 1811 dizzy patients (174 benign paroxysmal positional vertigo, 99 unilateral vestibulopathy, 67 bilateral vestibulopathy, 151 Menière's disease, 375 vestibular migraine, 82 cerebellar disorder, 522 functional dizziness, 341 unclear diagnosis) and in 59 healthy controls. Major findings were (i) a significant gender difference with higher directional deviations in females over the entire range of age, (ii) a significant increase of directional deviations with increasing age for both genders and in all disease subgroups as well as in healthy controls, and (iii) a lack of significant difference of directional deviations between all tested diseases. Thus, the data allow no recommendation for performing additional angular deviation analysis in dynamic SVV testing as part of routine clinical management of dizzy patients. However, as shown in earlier longitudinal studies, it still appears reasonable that dynamic SVV in acute rather than chronic vestibular disorders may provide a useful instrument for the monitoring of acute unilateral vestibular tonus imbalances in the course of the disease.

Subjective Visual Vertical test with the 3D virtual reality system: effective factors and cybersickness.

BACKGROUND: 3D Virtual Reality (VR) offers new opportunities in vestibular science. It also presents new challenges and problems. AIMS/OBJECTIVES: The study aimed to evaluate the effective factors in the 3D VR Subjective Visual Vertical (SVV) test and the impact of cybersickness on the test results. MATERIAL AND METHODS: The effect of the foam surface, head position in the yaw axis, moving background, and arm position holding the controller was tested. Cybersickness was evaluated using the Simulator Sickness Questionnaire (SSQ). RESULTS: The head position and controller holding style significantly affected the results. The foam surface and the moving background did not have a significant effect. Although 61.4% of the patients fell into the bad category according to the symptoms of the SSQ score, cybersickness did not significantly affect the SVV results. CONCLUSIONS AND SIGNIFICANCE: In 3D VR SVV, additional factors should be considered: the headset's weight, head position, and how we hold the controller. The A-effect emerged when the head was 45 degrees turned on the yaw axis. A significant shift was detected in the test, with the arm holding the controller at 90 degrees. Most subjects felt cybersickness at a considerable level. Cybersickness should always be taken into account in VR when planning new applications.

The value of vestibular graviceptive pathway evaluation in the diagnosis of unilateral peripheral vestibular dysfunction.

BACKGROUND: Evaluation of vestibular graviceptive pathway (VGP) in patients with unilateral peripheral vestibular dysfunction (UPVD) has received increasing attention from researchers. The study aimed to investigate the value of VGP evaluation in the diagnosis of UPVD. METHODS: Ninety-five UPVD patients were divided into attack and remission phase groups. VGP evaluation-related indicators, including subjective visual vertical (SVV), subjective visual horizontal (SVH), head tilt, ocular torsion (OT), and skew deviation (SD), were measured, and their correlations with cochleovestibular function test results were analyzed. The possible etiologies of contralesional VGP (c-VGP) were analyzed. RESULTS: Positive rates of SVV, SVH, OT, and SD were significantly higher, and the degrees of SVV, SVH, and OT were significantly greater in the attack phase group than the remission phase group. The sides with abnormal VGP evaluation results were correlated with the sides with hearing loss, abnormal caloric, and video head impulse test (vHIT) results. A total of 14 patients showed c-VGP, and possible etiologies included contralateral benign paroxysmal positional vertigo (n = 4), bilateral hearing loss (n = 8), bilateral vHIT gain reduction (n = 1), autoimmune diseases (n = 6), vascular risk factors (n = 6), lacunar infarction (n = 3), and endolymphatic hydrops (n = 3). CONCLUSIONS: Alterations in SVV, SVH, OT, and SD were noted in UPVD patients in different phases, which are presumed to be related to dynamic vestibular compensation; correlations between VGP evaluation results and cochleovestibular function test results indicate that VGP evaluation may be helpful for the diagnosis of the side affected in UPVD; the presence of c-VGP may be related to bilateral labyrinth lesions or endolymphatic hydrops on the affected side; and the involvement of autoimmune mechanisms also deserves attention.

A study of otolith function in patients with orthostatic dizziness.

BACKGROUND: Orthostatic dizziness (OD) is the dizziness that occurs when moving from a sitting or a supine to a standing position. It is typically thought to be connected to orthostatic hypotension (OH). The otolithic control of respiratory and cardiovascular system through vestibulosympathetic reflex has been the focus of considerable recent interest. This study aimed to evaluate the relationship between the orthostatic dizziness and otolith organ function. METHODS: This study was carried on 50 adults aged from 18 to 50 years with normal peripheral hearing. Subjects were divided into two groups: controls (GI): 20 healthy adults and study group (GII): 30 patients who were complaining of OD. Patients were submitted to; blood pressure measurement in sitting and standing positions, combined vestibular-evoked myogenic potentials (VEMPs) and subjective visual vertical and horizontal tests (SVV) and (SVH). RESULTS: The study group showed abnormal absent cVEMP, oVEMP. There were also statistically significant differences of P13 and N23 latencies and (P13N23) amplitudes between the two groups in the left ears. Both groups differed significantly in SVH values deviated to the left side. Study group were further subdivided into ten patients with OH and 20 patients with OD without OH. The both study subgroups showed abnormal absent cVEMP, oVEMP and abnormal SVH. OH patients showed statistically significant differences of cVEMP waves P13, N23 latencies in the left ears when compared with the control. CONCLUSIONS: Otolith malfunction may be the cause of orthostatic dizziness (OD) in patients with and without orthostatic hypotension.

Application of supervised machine learning algorithms for the evaluation of utricular function on patients with Meniere's disease: utilizing subjective visual vertical and ocular-vestibular-evoked myogenic potentials.

BACKGROUND: Research on the otolith organs remains inconclusive. OBJECTIVES: This study seeks to further elucidate utricular function in patients with Meniere's disease (MD) in three ways: (1) We aimed to disambiguate the role of the Subjective Visual Vertical (SVV) and Ocular Vestibular Evoked Myogenic Potential (o-VEMP) tests regarding which utricular subsystem each is measuring. (2) We sought to characterize the acute and chronic state of MD by identifying differences in the relationship of SVV and o-VEMP results across patients with acute and chronic MD. (3) We attempted to find a machine-learning algorithm that could predict acute versus chronic MD using SVV and o-VEMP. METHODS: A prospective study with ninety subjects. RESULTS: (1) SVV and o-VEMP tests were found to have a moderate linear relationship in patients with acute MD, suggesting each test measures a different utricular subsystem. (2) Regression analyses statistically differed across the two patient populations, suggesting that SVV results were normalized in chronic MD patients. (3) Logistic regression and Naïve Bayes algorithms were found to predict acute and chronic MD accurately. SIGNIFICANCE: A better understanding of what diagnostic tests measure will lead to a better classification system for MD and more targeted treatment options in the future.

Comparison of Asymmetry between Perceptual, Ocular, and Postural Vestibular Screening Tests.

BACKGROUND: A better understanding of how vestibular asymmetry manifests across tests is important due to its potential implications for balance dysfunction, motion sickness susceptibility, and adaptation to new environments. OBJECTIVE: We report the results of multiple tests for vestibular asymmetry in 32 healthy participants. METHODS: Asymmetry was measured using perceptual reports during unilateral centrifugation, oculomotor responses during visual alignment tasks, vestibulo-ocular reflex gain during head impulse tests, and body rotation during stepping tests. RESULTS: A significant correlation was observed between asymmetries of subjective visual vertical and verbal report during unilateral centrifugation. Another significant correlation was observed between the asymmetries of ocular alignment, vestibulo-ocular reflex gain, and body rotation. CONCLUSIONS: These data suggest that there are underlying vestibular asymmetries in healthy individuals that are consistent across various vestibular challenges. In addition, these findings have value in guiding test selection during experimental design for assessing vestibular asymmetry in healthy adults.