Variability in the Results of Vestibular Assessment in Patients with Genetically Confirmed Cerebellar Ataxia, Neuropathy, and Vestibular Areflexia Syndrome.

BACKGROUND: Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) presents an unpredictable and uneven clinical development of cerebellar ataxia, neuropathy, and vestibular areflexia. The aim of this study is to report the variability of vestibular test results in genetically confirmed patients with cerebellar ataxia, neuropathy, and vestibular areflexia syndrome. METHODS: Caloric testing, video head impulse test (vHIT), and rotatory chair testing were performed in 7 patients who presented pathogenic repeat expansions in the replication factor complex unit 1 gene related to cerebellar ataxia, neuropathy, and vestibular areflexia syndrome. RESULTS: Reduced vestibulo-ocular reflex (VOR) gain was observed in 100% of the patients in rotatory chair testing. Three of them had bilateral areflexia in caloric testing while 2 showed unilateral hypofunction and 2 had no alterations in the test. Only 1 patient had bilateral abnormal vHIT with gains under 0.6 in both ears. CONCLUSION: Genetic testing allows an early diagnosis of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome, whereby the vestibular system may be affected to different degrees. Rotatory chair testing has a higher sensitivity for the detection of vestibular hypofunction in these patients. Caloric testing can provide additional information. vHIT might underdiagnose patients with mild-to-moderate vestibulopathy.

Assessment of vestibulo-ocular reflex with video head impulse test in epilepsy patients undergoing carbamazepine monotherapy.

OBJECTIVE: Carbamazepine may cause clinical effects such as dizziness and nystagmus. This may depend on the duration of use. The aim of this study is to measure the effect of carbamazepine monotherapy on the vestibular system electrophysiologically by using Video Head Impulse Test (VHIT) and to compare the numerical and objective data obtained between the groups. PATIENTS AND METHODS: In this study, in which 55 people (110 ears) participated, Video Head Impulse Test (VHIT) was performed to evaluate the vestibulo-ocular reflex (VOR) in the epilepsy patients and a healthy control group consisting of healthy individuals. In addition, patients were analyzed in two groups to demonstrate the long-term effects of carbamazepine (<10 years and >10 years). Right/left lateral, anterior, posterior semi-circular canals (SCCs) VOR gains, lateral, left anterior right posterior, and right anterior right posterior gain asymmetries were measured between groups. RESULTS: Lateral SCCs VOR gains were 0.878±0.057 and 0.921±0.045 between the patient and healthy control groups, respectively (p=0.024). A decrease in the right and left lateral SCCs VOR gains (0.885±0.062 and 0.868±0.063) was detected in the patients (p=0.011 and p=0.001). Those using carbamazepine for >10 years had a decrease in lateral SSCs VOR gains (0.843±0.055) compared to those using the drug for <10 years (0.902±0.046) (p=0.008). CONCLUSIONS: A relative reduction in lateral (right/left) SCCs VOR gains was found in epilepsy patients using carbamazepine and in the group of patients using this drug for a long time (>10 years).

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.

Assessment of the Clinical Use of Vestibular Evoked Myogenic Potentials and the Video Head Impulse Test in the Diagnosis of Early-Stage Parkinson's Disease.

OBJECTIVES: To explore the usefulness of vestibular tests including "vestibular evoked myogenic potentials" (VEMPs) and the video head impulse test (vHIT) in the early diagnosis of "idiopathic Parkinson's disease" (PD). MATERIALS AND METHODS: The study involved 80 participants including 40 patients (24 males, 16 females; age average 63.20 ± 7.94 years) with PD and 40 healthy individuals (18 males and 22 females; age average of 60.36 ± 7.68 years). The Modified Hoehn and Yahr (H&Y) scale was used to measure how Parkinson's symptoms progress and the level of disability. Patients with PD underwent cVEMPs, oVEMPs, and vHIT and the results were compared with those of 40 age-matched healthy control (HC) subjects. vHIT results and VEMP responses were registered in all patients and HCs. RESULTS: One-sided absent cVEMP responses were found in 6 (15%) patients with PD and 8 (20%) patients had bilaterally absent responses. Five (12.5%) patients had 1-sided absent oVEMP responses and it was bilateral in 6 (15%). Patients with PD had significantly shorter cVEMP P1, N1 latency, lower cVEMP amplitudes, and oVEMP amplitudes than the HC group. The cVEMP and oVEMP amplitude asymmetry ratio was significantly higher in the PD group (P < .05). Evaluation of vHIT results and vestibular-ocular reflex (VOR) gain between the groups revealed that anterior canal and posterior canal VOR gains results were remarkably lower in the PD group than in the HCs (P < .05). There was no difference in right and left lateral canal VOR gains between the groups (P > .05). CONCLUSION: The results of this study suggest that cVEMP and vHIT can be used to evaluate the vestibular system in patients with early-stage Parkinson's disease.

Does the video head impulse test replace caloric testing in the assessment of patients with chronic dizziness? A systematic review and meta-analysis / O video head impulse test substitui a prova calórica na avaliação de pacientes com tontura crônica? Uma revisão sistemática e metanálise

Abstract Introduction: Caloric testing is the most frequently used test to assess peripheral vestibular function since the beginning of the 20th century. However, the video head impulse test, vHIT, has gained prominence in the field of neurotology, as it is a faster examination, easier to perform and less uncomfortable for the patient. Objective: To compare, through systematic review and meta-analysis, the proportion of altered cases between vHIT tests and caloric testing in patients with chronic dizziness, in addition to assessing the sensitivity and specificity of vHIT, with caloric testing as the gold standard. Methods: The literature search was carried out in the PubMed, Scopus, BVS-Bireme, Web of Science, Embase, Cochrane and ProQuest indexed databases, with no restrictions regarding the publication period. All articles that contained the results of the two tests were included in the evaluation of patients with dizziness. Two researchers independently conducted data selection and extraction from the studies, strictly following the inclusion and exclusion criteria defined in the research protocol. In case of disagreement during the selection, a discussion was carried out with a third evaluator. Results: Eleven of the 1293 initial articles met the eligibility criteria and were analyzed. 2670 patients were evaluated, of which 1112 (41.6%) were males and 1558 (58.4%) females, with a mean age of 51.6 years. The proportion of altered results in the vHIT was 21% (95%CI 9% --33%), and 55% in the caloric testing (95%CI 43% --67%). Conclusion: The vHIT does not substitute for caloric testing. The tests are complementary in assessing the patient with dizziness, as they describe the tonotopy of the ampullary crest at different frequency ranges of stimulation. In chronic cases, the vHIT has a low sensitivity and high diagnostic specificity in comparison to caloric testing.

Resumo Introdução: A prova calórica é o exame mais usado para avaliação da função vestibular periférica desde os primórdios do século XX. Porém, o vídeo teste de impulso cefálico, vHIT, tem ganhado destaque no campo da otoneurologia por ser um exame mais rápido, de fácil execução e menos desconfortável para o paciente. Objetivo: Comparar, através de revisão sistemática e metanálise, a proporção de casos alterados entre os exames vHIT e prova calórica nos pacientes com tontura crônica, além de avaliar a sensibilidade e especificidade do vHIT, tendo a prova calórica como padrão-ouro. Método: A busca na literatura foi feita nas bases de dados indexadas PubMed, Scopus, BVS-Bireme, Web of Science, Embase, Cochrane e ProQuest, sem restrições quanto ao período da publicação. Foram incluídos todos os artigos que tivessem os resultados dos dois exames na avaliação de pacientes com tontura. Dois pesquisadores conduziram de forma independente a seleção e extração de dados dos estudos, obedeceram rigorosamente os critérios de inclusão e exclusão definidos no protocolo de pesquisa. Em caso de discordância na seleção, fez-se discussão com um terceiro avaliador. Resultados: Onze dos 1.293 artigos iniciais preencheram os critérios de elegibilidade e foram analisados. Foram avaliados 2.670 pacientes, 1.112 (41,6%) do sexo masculino e 1.558 (58,4%) do feminino, com média de 51,6 anos. A proporção de exames alterados no vHIT foi de 21% (95% IC 9%-33%) e na prova calórica foi de 55% (95% IC 43%-67%). Conclusão: O vHIT não substitui a prova calórica. Ambos os testes são complementares na avaliação do paciente com tontura, pois descrevem a tonotopia da crista ampular em diferentes faixas de frequência de estimulação. Nos quadros crônicos, o vHIT tem baixa sensibilidade e alta especificidade diagnóstica em relação à prova calórica.

Changes in daily energy expenditure and movement behavior in unilateral vestibular hypofunction: Relationships with neuro-otological parameters.

The vestibular system has been found to affect energy homeostasis and body composition, due to its extensive connections to the brainstem and melanocortin nuclei involved in regulating the metabolism and feeding behavior. The aim of this study was to evaluate - by means of a wrist-worn physical activity tracker and bioelectrical impedance analysis (BIA) - the energy expenditure (EE) in resting (REE) and free-living conditions and movement behavior in a group of chronic unilateral vestibular hypofunction (UVH) patients when compared with a control group (CG) of healthy participants. Forty-six chronic UVH and 60 CG participants underwent otoneurological (including video-Head Impulse Test [vHIT] for studying vestibulo-ocular reflex [VOR] and static posturography testing [SPT]), and EE and movement measurements and self-report (SRM) andperformance measures (PM). As well as significant (p < 0.001) changes in SPT variables (area and path length) and SRM/PM, UVH participants also demonstrated significantly (p < 0.001) lower values in REE, movement EE, hours/day spent upright, number of strides and distance covered and total daily EE (p = 0.007) compared to the CG. UVH patients consumed significantly lower Kcal/min in sweeping (p = 0.001) and walking upstairs and downstairs (p < 0.001) compared to the CG. Multiple correlations were found between free-living and resting EE and neuro-otological parameters in UVH participants. Since the melanocortin system could be affected along the central vestibular pathways as a consequence of chronic vestibular deafferentation, data collected by reliable wearables could reflect the phenomena that constitute an increased risk of falls and sedentary lifestyle for patients affected by UVH, and could improve rehabilitation stages.

Assessment protocol and reference values of vestibulo-ocular reflex (VOR) gain in the horizontal plane recorded with video-Head Impulse Test (vHIT) in a pediatric population. / Protocolo de evaluación y valores de referencia de la ganancia del reflejo vestíbulo-ocular (RVO) en el plano horizontal registrado mediante el video-Head Impulse Test (v-HIT) en población pediátrica.

PURPOSE: To develop an assessment protocol and establish reference values of vestibulo-ocular reflex gain of the horizontal semicircular canal obtained with vHIT in a pediatric population without vestibular changes. METHODS: Quantitative, non-experimental, analytical study with a non-probabilistic convenience sample. A total of 39 subjects aged 5 to 17 years were selected based on the inclusion and exclusion criteria. RESULTS: The mean gain obtained of the horizontal right semicircular canal was 0.93 and of the left one, 1.08, with statistically significant differences between the ears. There were no statistically significant differences between the 5-to-10-year and 11-to-17-year subgroups. CONCLUSION: The vestibulo-ocular reflex gain in children neared the values found in the international scientific literature and the adult population. The protocol developed can guide beginning professionals in the otoneurological evaluation of children.

OBJETIVO: Elaborar un protocolo de evaluación y establecer valores de referencia de las ganancias del reflejo vestíbulo-ocular del canal semicircular horizontal obtenidas con el v-HIT en población pediátrica sin alteraciones vestibulares. MÉTODO: Estudio cuantitativo, analítico, no experimental con muestreo no probabilístico por conveniencia. Se seleccionaron 39 sujetos entre 5 a 17 años, los cuales cumplieron los criterios de inclusión y exclusión. RESULTADOS: El promedio de la ganancia obtenida para el conducto semicircular horizontal derecho fue de 0,93 y para el conducto semicircular izquierdo fue de 1,08. Existen diferencias estadísticamente significativas entre oídos. No existen diferencias estadísticamente significativas entre los subgrupos de 5 a 10 años y 11 a 17 años. CONCLUSIÓN: La ganancia del reflejo vestíbulo-ocular en población pediátrica se acerca a los valores encontrados en la literatura científica internacional y de la población adulta. El protocolo confeccionado puede orientar a profesionales que están comenzando en la evaluación otoneurológica de esta población.

Comprehensive Clinical Assessment of Vestibular Function in Multiple Sclerosis.

BACKGROUND AND PURPOSE: Balance disorders and dizziness are common in people with multiple sclerosis (MS), suggesting dysfunction of the vestibular system. Evaluating how people with MS perform on objective clinical vestibular tools will help broaden understanding of vestibular function in MS. This cross-sectional study's goal was to complete a robust battery of vestibular-ocular reflex (VOR), dynamic visual acuity (DVA), subjective visual vertical (SVV), and cervical and ocular vestibular-evoked myogenic potential (c/oVEMP) tests in people with and without MS. METHODS: Forty people with relapsing-remitting MS (Expanded Disability Status Scale [EDSS] ≤6.5) and 20 controls completed the vestibular testing battery. Results were compared between groups and correlations with EDSS scores were calculated. RESULTS: People with MS were less able to visually cancel their VOR and showed a larger variance in response on SVV. EDSS significantly correlated with VOR cancellation, SVV variance, and DVA lines lost; linear regression showed that VOR cancellation and SVV variance significantly predicted EDSS. DISCUSSION AND CONCLUSION: Vestibular functions requiring central integration of vestibular information, but not reflexive vestibular functions like VEMP, were impaired in people with MS and correlated with EDSS, suggesting that clinical evaluation of functions requiring central integration best evaluates MS-related vestibular dysfunction. Measures assessing central vestibular integration and not vestibular reflexes may be more sensitive to detecting vestibular deficits in people with mild to moderate MS.Video Abstract available for more insight from the authors (see Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A344).

Estimated Vestibulogram (EVEST) for Effective Vestibular Assessment.

BACKGROUND: The availability and development of methods testing the vestibuloocular reflex (VOR) brought a broader view into the lateral semicircular canal (L-SCC) function. However, the higher number of evaluated parameters makes more difficult the specialist's diagnose-making process. PURPOSE: To provide medical specialists, a new diagnostic-graphic tool, Estimated Vestibulogram- EVEST, enabling a quick and easy-to-read visualization and comparison of the VOR test results within the L-SCC. METHODS: The development of EVEST involved 148 participants, including 49 healthy volunteers (28 female and 21 male) and 99 (58 female and 41 male) patients affected by different degrees of peripheral vestibular deficit. The corresponding L-SCC VOR test results, from patients meeting the diagnostic criteria, were used to create the EVEST. RESULTS: Based on the test results, we depicted and calculated the EVEST vestibular function asymmetry (VFA) in all the groups. To assess a feasibility of EVEST to describe a vestibular function deficit, we calculated sensitivity and specificity of VFA using a receiver operating characteristic curve (ROC) and compared it to single tests. In all the tests, we determined the cutoff value as the point with the highest sensitivity and specificity. For discrimination of any vestibular deficit, the VFA with cutoff 6.5% was more sensitive (91%) and specific (98%) than single tests. Results showed that EVEST is a beneficial graphic tool for quick multifrequency comparison and diagnosis of different types of the peripheral vestibular loss. CONCLUSIONS: EVEST can help to easily evaluate various types of peripheral vestibular lesion.

Does the video head impulse test replace caloric testing in the assessment of patients with chronic dizziness? A systematic review and meta-analysis.

INTRODUCTION: Caloric testing is the most frequently used test to assess peripheral vestibular function since the beginning of the 20th century. However, the video head impulse test, vHIT, has gained prominence in the field of neurotology, as it is a faster examination, easier to perform and less uncomfortable for the patient. OBJECTIVE: To compare, through systematic review and meta-analysis, the proportion of altered cases between vHIT tests and caloric testing in patients with chronic dizziness, in addition to assessing the sensitivity and specificity of vHIT, with caloric testing as the gold standard. METHODS: The literature search was carried out in the PubMed, Scopus, BVS-Bireme, Web of Science, Embase, Cochrane and ProQuest indexed databases, with no restrictions regarding the publication period. All articles that contained the results of the two tests were included in the evaluation of patients with dizziness. Two researchers independently conducted data selection and extraction from the studies, strictly following the inclusion and exclusion criteria defined in the research protocol. In case of disagreement during the selection, a discussion was carried out with a third evaluator. RESULTS: Eleven of the 1293 initial articles met the eligibility criteria and were analyzed. 2670 patients were evaluated, of which 1112 (41.6%) were males and 1558 (58.4%) females, with a mean age of 51.6 years. The proportion of altered results in the vHIT was 21% (95%CI 9% -33%), and 55% in the caloric testing (95%CI 43% -67%). CONCLUSION: The vHIT does not substitute for caloric testing. The tests are complementary in assessing the patient with dizziness, as they describe the tonotopy of the ampullary crest at different frequency ranges of stimulation. In chronic cases, the vHIT has a low sensitivity and high diagnostic specificity in comparison to caloric testing.

VEMPs and Dysautonomia Assessment in Definite Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS): a Case Series Study.

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a recently described slowly progressive ataxia with severe imbalance due to the compromise of three of the four sensory inputs for balance, leaving only vision unaffected. Bilateral vestibulopathy is present but saccular and utricular function, measured by vestibular evoked myogenic potentials (VEMPs), has not been widely studied in these patients. Dysautonomia has been reported but is not among the diagnostic criteria. We performed a database analysis to identify patients evaluated between 2003 and 2019 with probable diagnosis of CANVAS by using key words "bilateral vestibulopathy and/or cerebellar ataxia and/or sensory polyneuropathy." Five out of 842 met all conditions. Patients underwent neurological/neurootological exam, brain MRI, visually enhanced vestibulo-ocular reflex (VVOR) exam by high-speed video-oculography using video-Head Impulse Test (vHIT), VEMPs, neurophysiological studies, and genetic tests to exclude other causes of ataxia. Dysautonomia was addressed by the standardized survey of autonomic symptoms. All patients had clinically definite CANVAS as brain MRI showed vermal cerebellar atrophy, neurophysiological studies showed a sensory neuronopathy pattern (absent sensory action potentials), VVOR was abnormal bilaterally, and genetic tests ruled out other causes of ataxia including SCA 3 and Friedreich ataxia. Patients had at least 3 dysautonomic symptoms, including xerostomia/xerophthalmia (5/5). VEMP results varied among patients, ranging from normal to completely abnormal. We found inconsistent results with VEMPs. The utilization of VEMPs in more CANVAS cases will determine its utility in this syndrome. Dysautonomia may be included in the diagnostic criteria.

Vestibular function assessment following cochlear implantation using rotatory chair testing.

PURPOSE: Study aimed to assess short- and long-term impact of unilateral cochlear implantation in children on the angular vestibulo-ocular reflex using rotatory chair test. METHODS: Two groups; A (early postoperative evaluation) and B (later on evaluation) were included, each consisted of 23 cochlear implant candidates' children with unilateral implant surgeries were performed in El-Galaa Hospital, Cairo, Egypt. They were assessed by rotatory chair test; sinusoidal harmonic acceleration paradigm. Three parameters: average gain, asymmetry, and phase results of each group were compared with the manufacturer's norms and with each other. Further analysis by comparing each group implanted side specific gain results with the same group non-implanted side specific gain and with the other group implanted side specific gain results. RESULTS: Group A versus norms showed only significant differences in average gain and phase at 0.02 Hz and 0.01 Hz test frequencies respectively. However, three parameters in group B showed no significant differences when compared with norms. When comparing the results of both groups relieved significant differences only in average gain at 0.02 Hz and in phase at both 0.01 Hz and 0.04 Hz. Comparing specific gain results for both sides of group A showed significance at 0.32 Hz test frequency, while those of group B showed no significant differences. The analysis of implanted sides gain results of both groups showed differences at 0.16 Hz and 0.32 Hz. CONCLUSION: Bilateral restoration and improvement of angular vestibulo-ocular reflexes after unilateral cochlear implantation was reported with long-term assessment by rotatory chair test.

Assessment of the effects of menopause on semicircular canal using the video head impulse test.

This cross-sectional study included early menopausal and late menopausal women aged between 40 and 60 years to evaluate the effects of menopause on semicircular canal function. A video head impulse test (vHIT) was performed for all subjects. Vestibulo-ocular reflex (VOR) mean gains of each semicircular canal and gain asymmetry were compared between groups. Of the 87 subjects, 37(42.5%) were reproductive age 28(32.5%) were early menopausal and 22(25.3%) were late menopausal patients. VOR gain of semicircular canals or gain asymmetry values did not differ between groups. In postmenopausal women, presence of vasomotor symptoms was associated with higher gain asymmetry of the left anterior-right posterior (LARP) plane (p = .01), and presence of balance problems was associated with lower right anterior (RA) VOR gain (p = .01). In conclusion semicircular canal function in postmenopausal women was similar to that in women of reproductive age.IMPACT STATEMENTWhat is already known on this subject? During menopause, women face potential risks such as dizziness, balance problems, falls and fractures. Postmenopausal patients were tested with dynamic posturography to measure balance before and after oestrogen treatment, and it was shown that balance problems significantly improved with oestrogen treatment. Healthy vestibular system is one of the components for sustaining normal balance.What do the results of this study add? In postmenopausal women the function of the semicircular canals is normal and the balance deficit in postmenopausal women may not be caused by the vestibular system. In this study changes within normal limits were observed in vestibular system of postmenopausal women.What are the implications of these findings for clinical practice and/or further research? Reported balance deficits might have been due to central origin. Further research to differentiate origin of balance deficits are needed. Specific research on symptomatic postmenopausal patients would reveal more information.

Protocolo de evaluación y valores de referencia de la ganancia del reflejo vestíbulo-ocular (RVO) en el plano horizontal registrado mediante el video-Head Impulse Test (v-HIT) en población pediátrica / Assessment protocol and reference values of vestibulo-ocular reflex (VOR) gain in the horizontal plane recorded with video-Head Impulse Test (vHIT) in a pediatric population

RESUMEN Objetivo Elaborar un protocolo de evaluación y establecer valores de referencia de las ganancias del reflejo vestíbulo-ocular del canal semicircular horizontal obtenidas con el v-HIT en población pediátrica sin alteraciones vestibulares. Método Estudio cuantitativo, analítico, no experimental con muestreo no probabilístico por conveniencia. Se seleccionaron 39 sujetos entre 5 a 17 años, los cuales cumplieron los criterios de inclusión y exclusión. Resultados El promedio de la ganancia obtenida para el conducto semicircular horizontal derecho fue de 0,93 y para el conducto semicircular izquierdo fue de 1,08. Existen diferencias estadísticamente significativas entre oídos. No existen diferencias estadísticamente significativas entre los subgrupos de 5 a 10 años y 11 a 17 años. Conclusión La ganancia del reflejo vestíbulo-ocular en población pediátrica se acerca a los valores encontrados en la literatura científica internacional y de la población adulta. El protocolo confeccionado puede orientar a profesionales que están comenzando en la evaluación otoneurológica de esta población.

ABSTRACT Purpose To develop an assessment protocol and establish reference values of vestibulo-ocular reflex gain of the horizontal semicircular canal obtained with vHIT in a pediatric population without vestibular changes. Methods Quantitative, non-experimental, analytical study with a non-probabilistic convenience sample. A total of 39 subjects aged 5 to 17 years were selected based on the inclusion and exclusion criteria. Results The mean gain obtained of the horizontal right semicircular canal was 0.93 and of the left one, 1.08, with statistically significant differences between the ears. There were no statistically significant differences between the 5-to-10-year and 11-to-17-year subgroups. Conclusion The vestibulo-ocular reflex gain in children neared the values found in the international scientific literature and the adult population. The protocol developed can guide beginning professionals in the otoneurological evaluation of children.

Nondestructive and objective assessment of the vestibular function in rodent models: A review.

The normal function of the vestibular system is crucial for the sense of balance. The techniques used to assess the vestibular function plays a vital role in the research of the vestibular system. In this article, we have systematically reviewed some popular methods employing vestibular reflexes and vestibular evoked potentials for assessing the vestibular function in rodent models. These vestibular reflexes and vestibular evoked potentials to effective stimuli have been used as nondestructive and objective functional measures. The main types of vestibular reflexes include the vestibulo-ocular reflex (VOR), vestibulocollic reflex (VCR), and vestibulo-sympathetic reflex (VSR). They are all capable of indicating the functions of the semicircular canals and otoliths. However, the VOR assessment is much more prevalently used because of the relatively stereotypical inputoutput relationship and simple motion pattern of the ocular response. In contrast, the complicated motion pattern and small gain of the VCR response, as well as the undesired component possibly contributed from the acceleration receptors outside the labyrinths in the VSR response, restrict the widespread applications of VCR and VSR in the assessment of the vestibular system. The vestibular evoked myogenic potentials (VEMPs) and vestibular sensory evoked potentials (VsEPs) are the two typical evoked potentials that have been also employed for evaluating the vestibular function. Through exploiting different types of the VEMPs, the saccular and utricular functions can be evaluated separately. The sound-induced VEMPs, moreover, are capable of noninvasively assessing the unilateral vestibular function. The VsEPs, via the morphology of their signal waveforms, enable the access to the location-specific information that indicates the functional statuses of different components within the vestibular neural pathway.

Surgery-free video-oculography in mouse models: enabling quantitative and short-interval longitudinal assessment of vestibular function.

Vestibulo-ocular reflex (VOR) responding to acceleration stimuli is originated from the vestibular apparatuses and thus widely used as an in vivo indicator of the vestibular function. We have developed a vestibular function testing (VFT) system that allows to evaluate VOR response with improved efficiency. The previously required surgical procedure has been avoided by using a newly designed animal-immobility setup. The efficacy of our VFT system was demonstrated on the mice with vestibular abnormalities caused by either genetic mutations (Lhfpl5-/- or Cdh23-/-) or applied vestibulotoxicant (3,3'-iminodipropionitrile, IDPN). Daily longitudinal inspection of the VOR response in the IDPN-administered mice gives the first VOR-based daily-progression profile of the vestibular impairment. The capability of VOR in quantifying the severity of toxicant-induced vestibular deficits has been also demonstrated. The acquired VOR-measurement results were validated against the corresponding behavioral-test results. Further validation against immunofluorescence microscopy was applied to the VOR data obtained from the IDPN-administered mice. We conclude that the improved efficiency of our surgery-free VFT system, firstly, enables the characterization of VOR temporal dynamics and quantification of vestibular-impairment severity that may reveal useful information in toxicological and/or pharmaceutical studies; and, secondly, confers our system promising potential to serve as a high-throughput screener for identifying genes and drugs that affect vestibular function.

Assessment of Vestibulo-ocular Reflex Gain and Catch-up Saccades During Vestibular Rehabilitation.

OBJECTIVE: To assess, in patients referred to vestibular rehabilitation (VR) for persistence of disability after acute unilateral vestibulopathy (AUV), whether the video head impulse test (vHIT) can be a useful technique to define the efficacy of the treatment. STUDY DESIGN: Prospective clinical study. SETTING: Tertiary academic referral hospitals. PATIENTS: Thirty patients with residual symptoms after AUV were included. INTERVENTION: Patients underwent a 10-week VR program. MAIN OUTCOME MEASURES: Evaluation of dizziness handicap inventory score, high-velocity vestibulo-ocular reflex gain, asymmetry index, and catch-up saccade parameters before and after VR. RESULTS: All patients reported a clear clinical improvement after VR, also demonstrated by better dizziness handicap inventory scores (p < 0.001). A consistent increased gain and decreased asymmetry index were also observed (p < 0.001 for both). Patients did not show any change in covert catch-up saccades, while a statistically significant reduction of the number and amplitude of the overt catch-up saccades was interestingly detected (p = 0.009 and p = 0.030, respectively). CONCLUSION: VR is a valid approach for patients with residual disability after AUV. A reduction in number and amplitude of overt catch-up saccades seems useful to evaluate the efficacy of VR and to be related to clinical improvement.

[Etiology analysis and vestibular assessment of bilateral vestibular vestibulopathy].

Objective:To define clinical and laboratory characteristics of bilateral vestibulopathy(BVP) and to propose diagnostic criteria of this disorder based on clinical and laboratory vestibular function test findings.Method:Forty-two case series with a clinical suspicion of BVP were retrospectively analyzed, in an attempt to determine etiology. Presenting auditory-vestibular symptoms, bedside dynamic visual acuity tests and laboratory test were reviewed, including bithermal caloric test, rotatory chair tests, video head impulse test (vHIT), vestibular-evoked myogenic potentials (VEMP).Result:Among these 42 patients, dizziness was seen in 42 cases(100%), oscillopsia was seen in 21 cases(50%), hearing loss was seen in 30(71.4%). Eight cases(19%) had tinnitus. Twenty-five cases showed vestibular loss in dynamic visual acuity test (69.4%). Definite diagnosis of complete BVP was made in 36 patients when the patients showed abnormal findings on caloric test, rotatory chair test and vHIT in addition to the symptoms. Whereas probable diagnosis of partial BVP was obtained in 6 patients with abnormal caloric test and rotatory chair test but no pathological vHIT. VEMP (ocular or cervical) could be recorded in 20 patients. Fourteen cases were caused by ototoxic drugs while no causes could be determined in 6 cases among these 42 cases.Conclusion:The diagnosis of BVP is a challenge. Vestibular laboratory test battery which reflect full frequency function of VOR has great value to confirming the diagnosis and differentiate complete BVP to partial BVP. Diagnosis standard shall be made combining clinical history, characteristic symptoms and the results of auditory-vestibular function testing. Ototoxic drugs contribute most considering etiology.

A low-cost video-oculography system for vestibular function testing.

In order to remain in focus during head movements, vestibular-ocular reflex causes eyes to move in the opposite direction to head movement. Disorders of vestibular system decrease vision, causing abnormal nystagmus and dizziness. To diagnose abnormal nystagmus, various studies have been reported including the use of rotating chair tests and videonystagmography. However, these tests are unsuitable for home use due to their high costs. Thus, a low-cost video-oculography system is necessary to obtain clinical features at home. In this paper, we present a low-cost video-oculography system using an infrared camera and Raspberry Pi board for tracking the pupils and evaluating a vestibular system. Horizontal eye movement is derived from video data obtained from an infrared camera and infrared light-emitting diodes, and the velocity of head rotation is obtained from a gyroscope sensor. Each pupil was extracted using a morphology operation and a contour detection method. Rotatory chair tests were conducted with our developed device. To evaluate our system, gain, asymmetry, and phase were measured and compared with System 2000. The average IQR errors of gain, phase and asymmetry were 0.81, 2.74 and 17.35, respectively. We showed that our system is able to measure clinical features.