Evidence for the differential efficacy of yaw and pitch gaze stabilization mechanisms in people with multiple sclerosis.

People with multiple sclerosis (PwMS) who report dizziness often have gaze instability due to vestibulo-ocular reflex (VOR) deficiencies and compensatory saccade (CS) abnormalities. Herein, we aimed to describe and compare the gaze stabilization mechanisms for yaw and pitch head movements in PwMS. Thirty-seven PwMS (27 female, mean ± SD age = 53.4 ± 12.4 years old, median [IQR] Expanded Disability Status Scale Score = 3.5, [1.0]. We analyzed video head impulse test results for VOR gain, CS frequency, CS latency, gaze position error (GPE) at impulse end, and GPE at 400 ms after impulse start. Discrepancies were found for median [IQR] VOR gain in yaw (0.92 [0.14]) versus pitch-up (0.71 [0.44], p < 0.001) and pitch-down (0.81 [0.44], p = 0.014]), CS latency in yaw (258.13 [76.8]) ms versus pitch-up (208.78 [65.97]) ms, p = 0.001] and pitch-down (132.17 [97.56] ms, p = 0.006), GPE at impulse end in yaw (1.15 [1.85] degs versus pitch-up (2.71 [3.9] degs, p < 0.001), and GPE at 400 ms in yaw (-0.25 [0.98] degs) versus pitch-up (1.53 [1.07] degs, p < 0.001) and pitch-down (1.12 [1.82] degs, p = 0.001). Compared with yaw (0.91 [0.75]), CS frequency was similar for pitch-up (1.03 [0.93], p = 0.999) but lower for pitch-down (0.65 [0.64], p = 0.023). GPE at 400 ms was similar for yaw and pitch-down (1.88 [2.76] degs, p = 0.400). We postulate that MS may have preferentially damaged the vertical VOR and saccade pathways in this cohort.

Changes in vestibular-related responses to combined noisy galvanic vestibular stimulation and cerebellar transcranial direct current stimulation.

Vestibular nuclei and cerebellar function comprise vestibular neural networks that control vestibular-related responses. However, the vestibular-related responses to simultaneous stimulation of these regions are unclear. This study aimed to examine whether the combination of noisy galvanic vestibular stimulation (nGVS) and cerebellar transcranial direct current stimulation (ctDCS) using a complex transcranial electrical stimulation device alters vestibular-dominant standing stability and vestibulo-ocular reflex (VOR) function. The center of foot pressure (COP) sway and VOR of participants (28 healthy, young adults) were assessed under four conditions of transcranial electrical stimulation using nGVS and ctDCS. The COP was calculated with the participant standing on a soft-foam surface with eyes closed using a force plate to evaluate body sway. VOR measurements were collected via passive head movements and fixation on a target projected onto the front wall using a video head impulse test (vHIT). VOR gain was calculated in six directions using a semicircular canal structure based on the ratio of eye movement to head movement. The nGVS + ctDCS and nGVS + sham ctDCS conditions decreased COP sway compared to the sham nGVS + ctDCS and sham nGVS + sham ctDCS conditions. No significant differences were observed in the main effect of stimulation or the interaction of stimulation and direction on the vHIT parameters. The results of this study suggest that postural stability may be independently affected by nGVS. Our findings contribute to the basic neurological foundation for the clinical application of neurorehabilitation using transcranial electrical stimulation of the vestibular system.

Effects of valproic acid and levetiracetam monotherapy on balance functions in patients with generalized epilepsy.

BACKGROUND: It is reported that antiepileptic drugs have an effect on balance functions. The aim of the study was to evaluate and compare the effects of valproic acid and levetiracetam monotherapy on balance functions in patients with generalized epilepsy using objective test methods. METHODS: The study included 43 generalized epilepsy patients aged 18-60 years, including 20 patients receiving valproic acid monotherapy, 23 patients receiving levetiracetam monotherapy, and 25 healthy individuals as controls, in the Neurology Clinic of a university hospital in eastern Turkey. The demographic data form was filled out and the Video Head Impulse Test and Vestibular Evoked Myogenic Potentials test were performed. RESULTS: Statistically significant differences were obtained between the groups in lateral, posterior, and anterior semicircular canal gains and RALP and LARP asymmetry values in the V-HIT test (p < 0.05). Statistically significant differences were obtained between the groups in P1, N1 latency and asymmetry values in the C-VEMP test and in N1, P1 latency, amplitude, and asymmetry values in the o-VEMP test (p < 0.05). CONCLUSION: Valproic acid and levetiracetam may affect the vestibulocular and vestibulocolic reflex pathways negatively. In this cohort, valproic acid had more pronounced adverse effects on balance functions as compared to levetiracetam.

Impact of endolymphatic hydrops on the function of the horizontal canal during caloric stimulation in Ménière's disease.

PURPOSE: When a dizzy patient with episodic vertigo has an abnormal caloric and a normal video head impulse test (vHIT), this caloric-vHIT dissociation provides vital information for a diagnosis of Ménière's disease (MD). Endolymphatic hydrops (EH), a histological marker of MD, is hypothesized to be involved in the caloric-vHIT dissociation in MD through hydropic duct distension of the horizontal semicircular canal (SC). This study was designed to determine the impact of EH on the function of horizontal SC during caloric stimulation. METHODS: Caloric test and vHIT were used to evaluate the function of horizontal SC every six months, annual magnetic resonance imaging (MRI) was used to evaluate the degree of EH size in the vestibule, and monthly vertigo and hearing evaluation was done for 12 months. EH shrinkage was defined as the size change of vestibular EH from significant to none. RESULTS: Among 133 MD patients evaluated for eligibility, 67 patients with caloric-vHIT dissociation entered the study. Fifteen participants had EH shrinkage (G-I), while 52 participants had no remarkable EH change (G-II). Average values (IQR) of the maximum slow phase velocity in G-I and G-II were 29.6 (13.0-34.0) and 25.9 (17.3-31.3), respectively, at baseline, 26.1 (9.0-38.0) and 23.6 (18.0-28.3) at 12 months. Two-factor repeated-measures ANOVA showed no significant differences between the groups (P = 0.486). The values of vestibulo-ocular reflex gain of the horizontal SC in G-I and G-II remained above 0.8 during the study period. CONCLUSIONS: EH detected by MRI shows limited correlation with caloric stimulation results.

Video head impulse test in subacute and chronic stroke survivors: new perspectives for implementation of assessment in rehabilitation.

INTRODUCTION: The Video Head Impulse Test (vHIT) is a safe and reliable assessment of peripheral vestibular function. Many studies tested its accuracy in clinical settings for differential diagnosis and quantification of the vestibulo-oculomotor reflex (VOR) in various disorders. However, the results of its application after lesions of the CNS are discordant and have never been studied in rehabilitation. This study aims to assess the VOR performance in a sample of stroke survivors. METHODS: This is a cross-sectional study on 36 subacute and chronic stroke survivors; only persons with first-ever stroke and able to walk independently, even with supervision, were included. We performed VOR assessments for each semicircular canal by vHIT and balance assessments by the Berg Balance Scale and the MiniBESTest scale. RESULTS: Two hundred and sixteen semicircular canals were assessed using the Head Impulse paradigm (in both the vertical and horizontal planes), while 72 semicircular canals were assessed using the Suppressed Head Impulse paradigm (horizontal plane). There was a high prevalence of participants with dysfunctional canals, particularly for the left anterior and right posterior canals, which were each prevalent in more than one-third of our sample. Furthermore, 16 persons showed an isolated canal dysfunction. The mean VOR gain for the vertical canals had confidence intervals out of the normal values (0.74-0.91 right anterior; 0.74-0.82 right posterior; 0.73-0.87 left anterior). CONCLUSION: Our findings suggest that peripheral vestibular function may be impaired in people with stroke; a systematic assessment in a rehabilitation setting could allow a more personalized and patient-centred approach.

Impact of audiovestibular factors on prognosis in patients with sudden sensorineural hearing loss without vertigo.

PURPOSE: This study aimed to investigate the hearing outcomes in patients with sudden sensorineural hearing loss without vertigo (SSNHLwoV). METHODS: Patients with SSNHLwoV managed from December 2016 to March 2020 were prospectively enrolled in an academic tertiary referral center. Fifty-one patients with SSNHLwoV who completed high-dose steroid treatment. The hearing prognosis was analyzed using a multivariate Cox regression model. RESULTS: The rates of complete, partial, and no hearing recovery were 52.9%, 17.6%, and 29.4% in patients with SSNHLwoV, respectively. The video head impulse test (vHIT) of the posterior semicircular canal (PSC), high-tone hearing loss (4-8 kHz) ≥ 30 dB, and average hearing threshold (0.5-1-2-4 kHz) were significantly associated with incomplete recovery of hearing after treatment. In multivariate analysis, the vHIT of the PSC (hazard ratio [HR], 14.502; 95% confidence interval [CI], 1.371-153.355) and high-tone hearing loss ≥ 30 dB (HR, 9.170; 95% CI, 2.283-36.830) remained robust. CONCLUSIONS: Abnormal vestibular function tests were performed in 80.4% of the patients with SSNHLwoV. Abnormal vHIT of the PSC and high-tone hearing loss ≥ 30 dB were independent factors resulting in incomplete recovery of hearing in patients with SSNHLwoV. In the SSNHLwoV cohort, the caloric test was not significantly associated with hearing prognosis, and vHIT was a feasible predictor of treatment outcome.

[Investigation of vestibular function in patients with vestibular neuritis]. / Issledovanie vestibulyarnoi funktsii u patsientov s vestibulyarnym neironitom.

Vestibular neuritis occupies the third place in terms of prevalence in the structure of peripheral vestibulopathies, therefore, the choice of optimal diagnostic and differential diagnostic tactics at different stages of the disease is an urgent task. OBJECTIVE: To optimize the diagnostic algorithm for vestibular neuritis based on an assessment of the sensitivity of clinical methods for studying vestibular function in the recovery period of the disease. MATERIAL AND METHODS: A comprehensive assessment of the sensitivity of clinical methods for the study of vestibular function in the acute (up to 14 days: at the time of initial treatment, on the 7th and 14th day) and subacute (up to 3 months: on the 28th and 90th day) periods of the disease in 52 patients with upper vestibular neuritis was carried out. RESULTS: The timing of the processes of restoration of vestibular function after a transferred vestibular neuritis is individual: after 14 days, restoration of vestibular function was recorded in 52% (n=27) patients, after 1 month - in 62% (n=32), after 3 months - in 71% (n=37) patients with upper vestibular neuritis. Statocoordination, statokinetic, oculomotor tests under visual control have the highest sensitivity in the acute period of vestibular neuritis, within up to 7 days from the onset of symptoms. In the subacute period of vestibular neuritis, the study of spontaneous nystagmus and nystagmus in the head shaking test retains high sensitivity only when using special tools (Frenzel goggles or videonystagmography). A decrease in the sensitivity of the head rotation test and the dynamic visual acuity test in the subacute period of vestibular neuritis is associated with the processes of central compensation and the formation of a latent saccade. CONCLUSION: The sensitivity of clinical tests in patients with vestibular neuritis depends on the timing of the examination.

Long-term dance training modifies eye-head coordination in response to passive head impulse.

Long-term dance training is known to improve postural control, especially in challenging postural tasks. However, the effect of dance training on the vestibulo-ocular reflex (VOR) has yet to be properly assessed. This study directly investigated whether VOR parameters are influenced by long-term dance training by testing dancers and controls using the video head impulse test. VOR gains using two of the most common methods (area ratio and instantaneous gains), latency and amplitude of the first saccade, if applicable, were computed. Results revealed a larger VOR gain as measured by area gain and instantaneous gain at 40 ms specifically for left-head impulses, but not right-head impulses. No significant differences in saccade frequency, amplitude, or latency were observed between groups. These differences appear to stem from a modified eye-to-head relationship during high-velocity head impulses in dancers. More specifically, the dancers' eyes lead head movement during passively applied head impulses, which result in higher VOR gain.NEW & NOTEWORTHY This study demonstrates, for the first time, that long-term dance training results in a nonlinear relationship between eye and head velocity within the first milliseconds following passive head impulse. The data also suggest a larger VOR gain in dancers. This finding suggests that dance training may modify eye-head relationship in passive high-frequency head movements. This is of particular interest for vestibular rehabilitation.

Determining the effect of obstructive sleep apnea syndrome on peripheral vestibular system and hearing.

There have been studies in the literature regarding the effect of obstructive sleep apnea syndrome on hearing function, but studies on the effect of obstructive sleep apnea syndrome on the peripheral vestibular system are limited. The aim of the present study was to determine whether obstructive sleep apnea syndrome causes functional neurological changes, particularly in the peripheral vestibular system, using the video head impulse test. Overall, 57 patients with obstructive sleep apnea syndrome were included; the 'Snorers' group comprised 20 volunteers diagnosed with simple snoring in the polysomnography test. The severity of apnea was assessed by monitoring cardiac and respiratory functions during sleep in both groups. The video head impulse test and audiological evaluations were performed in both groups. Statistically significant differences were found in the cochlea and semicircular canals of our patients in the video head impulse test and audiological battery tests. It may be assumed that decreased blood oxygen concentrations and chronic hypoxaemia have negative effects on the vestibule, cochlear sensory epithelium, and the auditory pathways. We think that inner ear structures and pathways may be affected due to hypoxia in obstructive sleep apnea syndrome. Therefore, screening patients with obstructive sleep apnea syndrome with an audiometry battery may help to detect inner ear pathologies early.

Assessment of vestibulo-ocular reflex and its adaptation during stop-and-go car rides in motion sickness susceptible passengers.

Motion sickness is a physiological condition that negatively impacts a person's comfort and will be an emerging condition in autonomous vehicles without proper countermeasures. The vestibular system plays a key role in the origin of motion sickness. Understanding the susceptibility and (mal) adaptive mechanisms of the highly integrated vestibular system is a prerequisite for the development of countermeasures. We hypothesize a differential association between motion sickness and vestibular function in healthy individuals with and without susceptibility for motion sickness. We quantified vestibular function by measuring the high-frequency vestibulo-ocular reflex (VOR) using video head impulse testing (vHIT) in 17 healthy volunteers before and after a 11 min motion sickness-inducing naturalistic stop-and-go car ride on a test track (Dekra Test Oval, Klettwitz, Germany). The cohort was classified as motion sickness susceptible (n = 11) and non-susceptible (n = 6). Six (out of 11) susceptible participants developed nausea symptoms, while a total of nine participants were free of these symptoms. The VOR gain (1) did not differ significantly between participant groups with (n = 8) and without motion sickness symptoms (n = 9), (2) did not differ significantly in the factor time before and after the car ride, and showed no interaction between symptom groups and time, as indicated by a repeated measures ANOVA (F(1,15) = 2.19, p = 0.16. Bayesian inference confirmed that there was "anecdotal evidence" for equality of gain rather than difference across groups and time (BF10 < 0.77). Our results suggest that individual differences in VOR measures or adaptation to motion sickness provocative stimuli during naturalistic stop-and-go driving cannot predict motion sickness susceptibility or the likelihood of developing motion sickness.

Refining the Video Head Impulse Test Diagnostic Accuracy: A Case-Control Study.

INTRODUCTION: Current clinical practice considers the vestibulo-ocular reflex (VOR) gain as registered by the video head impulse test (vHIT) as the primary measure for semicircular canal function, while the role of the re-fixation saccades (RSs) is still under evaluation. The goal of the study was to appraise the added benefit of RS towards the improvement of vHIT diagnostic accuracy in cases of suspected left horizontal semicircular canal dysfunction. METHODS: The vHIT recordings of 40 patients with left-sided horizontal VOR gains <0.8 were retrospectively evaluated for the presence of RS. The study groups included 20 patients with a final diagnosis of left horizontal semicircular canal dysfunction and 20 patients for whom vestibular dysfunction was ruled out. RESULTS: Gain values >0.72 were found in all patients with no vestibular disease and in 4 (20%) patients having vestibulopathy. Significantly higher average left-sided RS velocity and frequency were found among the vestibular patients. VOR gain <0.72 was found to be highly specific for the diagnosis of vestibular dysfunction. However, for gain values in the range of 0.72-0.79, the presence of RS with frequency >80% largely improved vHIT diagnostic accuracy. CONCLUSIONS: Although VOR gain <0.8 is considered to reflect dysfunction, a significant false-positive rate for left-sided horizontal vHIT was found for gains in the range of 0.72-0.79. The presence of RS with frequency >80% could improve vHIT diagnostic ability in these patients.

Recurrent Vestibulopathy: Comparison of Vestibular Test Results with Ménière's Disease and Vestibular Migraine.

INTRODUCTION: Recurrent and episodic vestibular symptoms not fulfilling criteria for known episodic vestibular syndromes are named as recurrent vestibulopathy (RV). We aimed to compare the vestibular test results of RV patients with vestibular migraine (VM) and Ménière's disease (MD). METHODS: Twenty patients with MD, 20 patients with VM, 18 patients with RV, and 20 healthy volunteers (HC) were evaluated. Pure-tone hearing thresholds (PTHTs), video head impulse test (vHIT), functional head impulse test (fHIT), and cervical vestibular evoked myogenic potentials (cVEMPs) were studied. RESULTS: PTHT of the MD-affected ears were significantly high, and cVEMP-corrected amplitudes were low when compared with the VM, RV, and HC (p < 0.001 for all). Amplitude asymmetry ratio was significantly high in MD-affected ears when compared with the HC (p = 0.014), VM (p = 0.038), and RV (p = 0.045). VEMP latencies and lateral canal vHIT gain were not different between groups (p > 0.05). The percentage of correctly identified optotypes on fHIT of the MD (p > 0.001), VM (p = 0.004), and RV (p = 0.001) patients were low in comparison with the HC. CONCLUSION: Apart from hearing loss, low cVEMP amplitudes on the affected side were the main feature in MD differentiating it from VM and RV. Vestibular test results of patients with RV and VM were similar. Low fHIT results in all groups indicate a functional deficit in gaze stabilization. Disabling vertigo attacks disturbing attention may be the cause of this functional impairment. MD, VM, and RV may be parts of a broad-spectrum disorder, RV patients representing milder forms not associated with cochlear or migrainous features.

Long-term outcome of vestibular function and hearing in children with congenital cytomegalovirus infection: a prospective cohort study.

PURPOSE: Congenital cytomegalovirus infection (cCMV) is the most frequent nonhereditary cause for sensorineural hearing loss (SNHL) in children. Data on vestibular function in children with cCMV are, however, scarce, although some evidence for cCMV-associated vestibular dysfunction exists. In this prospective cohort study, we evaluated long-term vestibular function and hearing outcomes in a cohort of children with cCMV. METHODS: Participants were 6-7-year-old children with cCMV from a large population-based screening study. Controls were age and gender matched healthy children, who were CMV-negative at birth. Hearing was examined with pure tone audiometry. Definition of hearing loss was pure-tone average > 20 dB. Vestibular function was assessed using the video head impulse test that provides a measure of semicircular canal function. Definition of vestibular dysfunction was lateral semicircular canal gain < 0.75. RESULTS: Vestibular dysfunction occurred in 7/36 (19.4%) of children with cCMV and in 1/31 (3.2%) of controls (p = 0.060). SNHL was recorded in 4/38 (10.5%) of children with cCMV and in 0/33 of controls (p = 0.118). Hearing loss was unilateral in all cases. In cCMV group, the two children with bilateral vestibular dysfunction also had SNHL, whereas those with unilateral vestibular dysfunction (n = 5) had normal hearing. CONCLUSIONS: In this cohort of children with cCMV identified using newborn screening, vestibular dysfunction was more common than SNHL at 6 years of age. Vestibular dysfunction occurred both in children with and without SNHL. Based on these data, inclusion of vestibular tests in follow-up protocol of cCMV should be considered.

Normative values for the video Head Impulse Test in children without otoneurologic symptoms and their evolution across childhood by gender.

PURPOSE: The video Head Impulse Test is routinely used to assess semicircular canal function in adults, but to date, pediatric reference values are scarce. This study aimed to explore the vestibulo-ocular reflex (VOR) in healthy children at different development stages and to compare the obtained gain values with reference to those in an adult population. METHODS: This prospective, single-center study recruited 187 children from among patients without otoneurological diseases, healthy relatives of these patients, and staff families from a tertiary hospital. Patients were divided into three groups by age: 3-6 years, 7-10 years, and 11-16 years. The vestibulo-ocular reflex was assessed by video Head Impulse Test, using a device with a high-speed infrared camera and accelerometer (EyeSeeCam®; Interacoustics, Denmark). RESULTS: We found a lower vestibulo-ocular reflex gain of both horizontal canals in the 3-6-year-old group when compared with the other age groups. No increasing trend was found in the horizontal canals from age 7-10 years to age 11-16 years, and no differences were found by sex. CONCLUSION: Gain values in the horizontal canals increased with age until children reached age 7-10 years and matched the normal values for adults.

Evaluation of postural stability and vestibulo-ocular reflex in adults with chronic suppurative otitis media.

PURPOSE: To evaluate the vestibulospinal reflex and vestibulo-ocular reflex (VOR) in patients with chronic suppurative otitis media (CSOM) using posturography and the video head impulse test (vHIT). METHODS: Sixty-five patients with CSOM and 65 healthy participants as controls were included. Patients with CSOM were instructed to complete the dizziness handicap inventory (DHI). All participants underwent otoscopy, pure-tone audiometry, posturography sensory organization test (SOT), and vHIT. RESULTS: Patients with CSOM exhibited a high prevalence of dizziness. The CSOM group had poor SOT vestibular scores compared to the control group. Patients with CSOM had worse sways in the antero-posterior and mediolateral planes. The CSOM group was divided into two subgroups according to the type of hearing loss. SOT vestibular scores were significantly poorer in the mixed hearing loss group than those in the conductive hearing loss group. We found a positive correlation between disease duration and poor SOT vestibular scores. Moreover, poor SOT vestibular scores correlated with high DHI scores. We found abnormalities in the vHIT results in the CSOM group in the form of low VOR gain and corrective saccades. CONCLUSION: Our study provides clinical evidence of dizziness, poor postural control, and VOR abnormalities in patients with CSOM. The presence of sensory elements of hearing loss in patients with CSOM appears to be positively associated with vestibular dysfunction.

Comparison between caloric and video-head impulse tests in Ménière's disease and vestibular neuritis.

OBJECTIVE: To compare the diagnostic accuracies of air caloric testing with electronystagmography and the vHIT (video-head impulse test). DESIGN: Prospective, controlled study. STUDY SAMPLE: MD (Ménière's disease), 26; vestibular neuritis, 27; control, 56. RESULTS: In MD, CP (canal paresis) was pathological in 88.5%, the GA (gain asymmetry) on vHIT was pathological in 65.3%, and the gain was abnormal in only one patient. The GA and CP, were significantly higher in the MD group than in the control group, indicating hypofunction of the horizontal canals in MD, whereas a hyperfunction may also occur. No correlation was observed between the results of the two tests for evaluating MD, suggesting that pathological outcomes of one test do not guarantee abnormalities on the other test. For vestibular neuritis, significantly higher CP (96.3%), GA (81.5%), and gain (51.9%) values were detected. A correlation was identified between the two tests for vestibular neuritis, indicating a similar diagnostic efficiency. The higher percentage of pathological GA versus pathological gain values indicates that the asymmetry may be more informative. CONCLUSIONS: The vHIT showed a higher specificity, whereas the caloric test a higher sensitivity. No correlation between the two methods was observed; therefore, the tests appear to provide complementary information.

Peripheral Vestibular System Involvement in Multiple Sclerosis and Associations with the Disease Severity.

INTRODUCTION: Multiple sclerosis (MS) is an autoimmune disease that can affect balance, gait, and improve fall risk. The aim of this study was to investigate peripheral vestibular system involvement in MS and associations with the disease severity. METHODS: Thirty-five adult patients with MS and 14 age- and gender-matched healthy controls were evaluated using video head impulse test (v-HIT), cervical vestibular evoked myogenic potential (c-VEMP), ocular vestibular evoked myogenic potentials (o-VEMPs), and sensory organization test (SOT) of computerized dynamic posturography (CDP). The results of both groups were compared, and association with EDSS scores was evaluated. RESULTS: There was no significant difference between the groups regarding v-HIT and c-VEMP results (p > 0.05). There was no association of the v-HIT, c-VEMP, and o-VEMP results with EDSS scores (p > 0.05). There was no significant difference between the o-VEMP results of the groups (p > 0.05) except for N1-P1 amplitudes (p = 0.01). The amplitudes of N1-P1 were significantly lower in the patients compared to controls (p = 0.01). There was no significant difference between the SOT results of the groups (p > 0.05). However, significant differences were found within and between groups when the patients were categorized according to their EDSS scores with a cutoff point of 3 (p < 0.05). There were negative correlations between the EDSS scores and composite (r = -396, p = 0.02) and somatosensory (SOM) scores (r = -487, p = 0.04) of CDP in the MS group. CONCLUSION: Although central and peripheral balance-related systems are affected in MS, the impact of disease on the peripheral vestibular end organ is subtle. In particular, the v-HIT, which was mentioned previously as a detector of brainstem dysfunction could not be a reliable tool in the detection of brainstem pathologies in MS patients. The o-VEMP amplitudes may be affected in the early stages of the disease, possibly due to the crossed ventral tegmental tract, oculomotor nuclei, or interstitial nucleus of Cajal involvements. An EDSS score >3 seems a cutoff level indicating abnormalities in balance integration.

Functional and Molecular Markers for Hearing Loss and Vertigo Attacks in Meniere's Disease.

Meniere's disease (MD) is one of the most complicated diseases in the otologic clinic. The complexity of MD is partially due to the multifactorial etiological mechanisms and the heterogenous symptoms, including episodic vertigo, hearing loss, aural fullness and tinnitus. As a result, the diagnosis of MD and differentiating MD from other diseases with similar symptoms, such as vestibular migraine (VM), is challenging. In addition, it is difficult to predict the progression of hearing loss and the frequency of vertigo attacks. Detailed studies have revealed that functional markers, such as pure tone audiometry (PTA), electrocochleography (ECochG), vestibular evoked myogenic potential (VEMP), caloric test, video head impulse test (vHIT) and magnetic resonance imaging (MRI) could help to evaluate MD with different hearing levels and frequency of vertigo attacks. Investigations of molecular markers such as autoimmunity, inflammation, protein signatures, vasopressin and circadian clock genes in MD are still underway. This review will summarize these functional and molecular markers, address how these markers are associated with hearing loss and vertigo attacks in MD, and analyze the results of the markers between MD and VM.

Influence of predictability on saccade timing in a head impulse VOR suppression task.

Gaze stabilization performance has been shown to be influenced differently when the head is either passively or actively moved in normal healthy participants. However, for a visual fixation suppression task, it remains unknown if the pattern of coordinated head and eye movement is influenced differently by passive or active head movements. We used a suppression head impulse paradigm (SHIMP), where the subject's goal was to maintain gaze stabilized on a visual target that moved with the head during rapid impulsive head movements, to evaluate gaze fixation performance in three conditions: (1) passive-unpredictable where the examiner applied impulsive head yaw rotations with random timing and direction, (2) passive-predictable where the direction of head rotation was announced and then the examiner repeatedly applied impulses in the same direction, and (3) active where the test subject self-generated their head movements. Thirteen young healthy adults performed all three conditions to assess the percentage of early saccades that initiated the gaze shift toward the final visual target position and the latency of first saccades. Early saccades were defined as those occurring within the duration of the head impulse. Results showed that active head impulses generated the greatest percentage of early saccades, followed by predictable and unpredictable. Among the two passive conditions, predictability shortened the first saccade onset latencies. Active condition onset latencies were shorter than in either of the passive conditions, showing a consistent head-leads-eye pattern defining a specific behavioral pattern that could vary across patient groups leading to insights into central neural mechanisms that control eye-head coordination.

Clinical use of child-friendly video head impulse test in dizzy children.

OBJECTIVE: To investigate the high-frequency vestibular functions using a child-friendly video head impulse test and to classify vestibular symptoms using a standard nomenclature guideline in dizzy children. MATERIALS AND METHODS: The video head impulse test with a remote camera was used in this study. The data of 40 dizzy children (7.30 ± 4.75 years) were analyzed retrospectively. RESULTS: The high-frequency vestibulo-ocular reflex gains of 14 (35%) dizzy children in the study group were reduced, whereas the vestibulo-ocular reflex gains of 26 (65%) dizzy children were normal. Two of them had a dramatic reduction in vestibulo-ocular reflex gains on their affected SCCs, but no corrective saccades as their gazes had not been fixated on the target at the onset of head impulses. In dizzy children, the most common cause was inner ear malformation (15%) and the most common vestibular symptom was unsteadiness (25%). CONCLUSION: The high-frequency vestibular function of the VOR in dizzy children, especially those suffering from IEM and unsteadiness, can be quickly screened using the vHIT device with the remote camera. However, clinicians should be careful during the interpretation of traces in the pediatric group.