[Subacute ataxia associated with cerebellar ataxia, neuropathy and vestibular areflexia (CANVAS)]. / Ataxia subaguda asociada a ataxia cerebelosa, neuropatía y arreflexia vestibular (CANVAS).

Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) is a late onset neurodegenerative disorder. Its genetic basis has recently been identified in the gene encoding a subunit of the Replication Factor C (RFC1). We present the case of a 62-year-old woman who experienced a history of a biphasic presentation of imbalance and gait disorders, with rapid onset of symptoms followed by slow and progressive neurological deterioration. The diagnostic process was challenging, and numerous tests were conducted to rule out acquired and genetic causes of ataxia, leading to a diagnosis of late-onset idiopathic cerebellar ataxia. Subsequently, vestibular function tests identified severe bilateral vestibulopathy. This led to considering CANVAS among the diagnoses, which was ultimately confirmed through genetic testing (biallelic expansion of the pentanucleotide AAGGG in the RFC1 gene). This case highlights the importance of this new described genetic disease and its subacute presentation variant, emphasizing the relevance of objective vestibular function tests in idiopathic ataxias to achieve proper diagnosis and eventual genetic counseling for offspring.

El síndrome de ataxia cerebelosa, neuropatía y arreflexia vestibular (CANVAS) es un trastorno neurodegenerativo progresivo que se manifiesta en etapas tardías de la vida. Su base genética ha sido recientemente identificada en el gen que codifica la subunidad 1 del factor C de replicación (RFC1). Presentamos el caso de una mujer de 62 años con una historial de desequilibrio y deterioro de la marcha de presentación bifásica, con un inicio rápido de los síntomas seguido de un deterioro neurológico lento y progresivo. El proceso diagnóstico fue complejo y se realizaron numerosas pruebas para descartar causas adquiridas y genéticas de la ataxia, arribando al diagnóstico de ataxia cerebelosa de inicio tardío idiopática. Ulteriormente, las pruebas de función vestibular identificaron una grave vestibulopatía bilateral. Esto llevó a considerar el CANVAS entre los diagnósticos, que finalmente fue confirmado mediante pruebas genéticas (expansión bialélica del penta-nucleótido AAGGG en el gen RFC1). Este caso subraya la importancia de esta nueva enfermedad genética y su variante de presentación subaguda y enfatiza la relevancia de las pruebas objetivas de función vestibular en las ataxias consideradas idiopáticas para lograr un diagnóstico adecuado y un eventual asesoramiento genético a la descendencia.

Universal Repositioning Maneuver: A New Treatment for Single Canal and Multi-Canal Benign Paroxysmal Positional Vertigo by 3-Dimensional Model Analysis.

BACKGROUND: Benign paroxysmal positional vertigo is the most common peripheral vestibular disorder and is currently treated by many types of repositioning maneuvers. A simplification of this procedure would be desirable. A new, anatomically realistic, 3-dimensional computational simulator of the human labyrinth provides a novel insight to evaluate the viability of any new maneuver. The purpose of this study is to propose a single maneuver with potential to treat canalolithiasis-type benign paroxysmal positional vertigo of any individual canal, or even multiple canals on the same side, based on a 3-dimensional model. METHODS: The benign paroxysmal positional vertigo Viewer, a 3-dimensional model of the human labyrinth, was used to analyze a "Universal Repositioning Maneuver." RESULT: Through the gravity vector, the expected position of the otoliths was demonstrated by moving the model through a single sequence of head positions, successfully promoting otolith migration from the three semicircular canals to the utricular cavity, either individually or together. CONCLUSION: The analysis with the 3-dimensional model predicts the effectiveness of the Universal Repositioning Maneuver for the resolution of each single canal or multiple-canal benign paroxysmal positional vertigo canalolithiasis, making treatment much more straightforward.

Social concepts and the cerebellum: behavioural and functional connectivity signatures in cerebellar ataxic patients.

Neurocognitive research on social concepts underscores their reliance on fronto-temporo-limbic regions mediating broad socio-cognitive skills. Yet, the field has neglected another structure increasingly implicated in social cognition: the cerebellum. The present exploratory study examines this link combining a novel naturalistic text paradigm, a relevant atrophy model and functional magnetic resonance imaging. Fifteen cerebellar ataxia (CA) patients with focal cerebellar atrophy and 29 matched controls listened to a social text (highlighting interpersonal events) as well as a non-social text (focused on a single person's actions), and answered comprehension questionnaires. We compared behavioural outcomes between groups and examined their association with cerebellar connectivity. CA patients showed deficits in social text comprehension and normal scores in the non-social text. Also, social text outcomes in controls selectively correlated with connectivity between the cerebellum and key regions subserving multi-modal semantics and social cognition, including the superior and medial temporal gyri, the temporal pole and the insula. Conversely, brain-behaviour associations involving the cerebellum were abolished in the patients. Thus, cerebellar structures and connections seem involved in processing social concepts evoked by naturalistic discourse. Such findings invite new theoretical and translational developments integrating social neuroscience with embodied semantics. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.

The Role of the Smartphone in the Diagnosis of Vestibular Hypofunction: A Clinical Strategy for Teleconsultation during the COVID-19 Pandemic and Beyond.

Introduction Vestibular disorders (VDs) are highly prevalent in primary care. Although in general they comprise conditions that are not life-threatening, they are associated with significant functional and physical disability. However, the current coronavirus disease 2019 (COVID-19) pandemic has imposed limitations on the standard treatment of benign conditions, including VDs. In this context, other resources may aid in the diagnosis and management of patients with VDs. It is well known that teleconsultation and teletreatment are both safe and effective alternatives to manage a variety of conditions, and we maintain that VDs should be among these. Objective To develop a preliminary model of clinical guidelines for the evaluation by teleconsultation of patients with suspected diagnosis of vestibular hypofunction during the COVID-19 pandemic and beyond. Methods A bibliographic review of the diagnostic feasibility in VDs by teleconsultation was carried out in the LILACS, SciELO, MEDLINE, and PubMed databases; books and specialized websites were also consulted. The legal, regulatory, and technical issues involving digital consultations were reviewed. Results We found 6 field studies published between 1990 and 2020 in which the efficiency of teleconsultations was observed in the contexts of epidemics and environmental disorders and disadvantageous geographical conditions. After reviewing them, we proposed a strategy to examine and address vestibular complaints related to vestibular hypofunction. Conclusion The creation of a digital vestibular management algorithm for the identification, counseling, initial intervention, monitoring and targeting of people with possible vestibular hypofunction seems to be feasible, and it will provide a reasonable alternative to in-person evaluations during the COVID-19 pandemic and beyond.

The spectrum of acute vestibular neuropathy through modern vestibular testing: A descriptive analysis.

OBJECTIVE: Acute vestibular neuropathy (AVN), often referred to as vestibular neuritis, is a cranial neuropathy responsible for a significant proportion of cases of acute vertigo. This study describes the spectrum of lesion patterns in AVN as identified by video head impulse testing (vHIT) which assesses the high frequency vestibulo-ocular reflex function of the semicircular canals, and cervical and ocular vestibular evoked myogenic potentials (VEMPs) which assess otolith function. METHODS: We used vHIT and VEMPs to assess 35 patients with vestibular neuropathy in the acute stage. RESULTS: Unilateral superior division vestibular nerve involvement was the most common variant (57.1%), followed by unilateral superior and inferior division (28.5%), bilateral superior division (8.5%) and unilateral inferior division (5.7%). We observed a partial inverse correlation between the proportion of afferent fibers from an organelle, and the likelihood that the test of that organelle's function will be abnormal. CONCLUSION: vHIT and VEMPs provide more detailed characterization of lesion pattern in AVN than caloric testing. SIGNIFICANCE: Comparison of lesion patterns from neuro-physiological testing with what is known about the proportional distribution of afferent fibers from the vestibular end-organelles suggests a new, neuro-anatomically based insight regarding susceptibility of these pathways to AVN.

Square wave manoeuvre for apogeotropic variant of horizontal canal benign paroxysmal positional vertigo in neck restricted patients.

OBJECTIVE: We aimed to describe the clinical features of the apogeotropic variant of horizontal canal benign paroxysmal positional vertigo (HC BPPV-AG) in a cluster of patients with restrictive neck movement disorders and a new therapeutic manoeuvre for its management. METHODS: In a retrospective review of cases from an ambulatory tertiary referral center, patients with HC BPPV-AG in combination with neck movement restriction that prevented any classical manual repositioning procedure or who were refractory to canalith repositioning manoeuvres, were treated with a new manoeuvre comprised of sequential square-wave pattern of head and body supine rotations while nystagmus was being monitored, until either an apogeotropic to geotropic conversion or resolution of the nystagmus was observed. RESULTS: Fifteen patients were studied. All but one [14/15 cases] showed a positive therapeutic response to the repositioning procedure in a single session. In two cases, a direct relief of vertigo and elimination of nystagmus was observed without an intermediate geotropic phase. Although in three patients the affected ear was not initially identified, it was ultimately identified and successfully treated by the square wave manoeuvre in all of them. CONCLUSIONS: The square-wave manoeuvre is an alternative for HC BPPV-AG treatment in either cases with neck restriction, where the affected side is not well identified at the bedside or when other manoeuvres fail to resolve the HC BPPV-AG.

Teleconsultation and Teletreatment Protocol to Diagnose and Manage Patients with Benign Paroxysmal Positional Vertigo (BPPV) during the COVID-19 Pandemic.

Introduction Telehealth consists in the application of technology to provide remote health service. This resource is considered safe and effective and has attracted an exponential interest in the context of the COVID pandemic. Expanded to dizzy patients, it would be able to provide diagnosis and treatment, minimizing the risk of disease transmission. Benign paroxysmal positional vertigo (BPPV) is the most common vestibular disorder. The diagnosis typically rests on the description of the symptoms along with the nystagmus observed at a well-established positional testing. Objectives The aim of the present study was to propose a teleconsultation and teletreatment protocol to manage patients with BPPV during the COVID-19 pandemic. Methods Specialists in the vestibular field met through remote access technologies to discuss the best strategy to manage BPPV patients by teleconsultation and teletreatment system. Additionally, several scientific sources were consulted. Technical issues, patient safety, and clinical assessment were independently analyzed. All relevant information was considered in order to design a clinical protocol to manage BPPV patients in the pandemic context. Results Teleconsultation for BPPV patients requires a double way (video and audio) digital system. An adapted informed consent to follow good clinical practice statements must be considered. The time, trigger and target eye bedside examination (TiTRaTe) protocol has proven to be a valuable first approach. The bow and lean test is the most rational screening maneuver for patients with suspected positional vertigo, followed by most specific maneuvers to diagnostic the sub-variants of BPPV. Conclusion Although with limited evidence, teleconsultation and teletreatment are both reasonable and feasible strategies for the management of patients with BPPV in adverse situations for face-to-face consultation.

Teleconsultation and Teletreatment Protocol to Diagnose and Manage Patients with Benign Paroxysmal Positional Vertigo (BPPV) during the COVID-19 Pandemic

Abstract Introduction Telehealth consists in the application of technology to provide remote health service. This resource is considered safe and effective and has attracted an exponential interest in the context of the COVID pandemic. Expanded to dizzy patients, it would be able to provide diagnosis and treatment, minimizing the risk of disease transmission. Benign paroxysmal positional vertigo (BPPV) is the most common vestibular disorder. The diagnosis typically rests on the description of the symptoms along with the nystagmus observed at a well-established positional testing. Objectives The aim of the present study was to propose a teleconsultation and teletreatment protocol to manage patients with BPPV during the COVID-19 pandemic. Methods Specialists in the vestibular field met through remote access technologies to discuss the best strategy to manage BPPV patients by teleconsultation and teletreatment system. Additionally, several scientific sources were consulted. Technical issues, patient safety, and clinical assessment were independently analyzed. All relevant information was considered in order to design a clinical protocol to manage BPPV patients in the pandemic context. Results Teleconsultation for BPPV patients requires a double way (video and audio) digital system. An adapted informed consent to follow good clinical practice statements must be considered. The time, trigger and target eye bedside examination (TiTRaTe) protocol has proven to be a valuable first approach. The bow and lean test is the most rational screening maneuver for patients with suspected positional vertigo, followed by most specific maneuvers to diagnostic the sub-variants of BPPV. Conclusion Although with limited evidence, teleconsultation and teletreatment are both reasonable and feasible strategies for the management of patients with BPPV in adverse situations for face-to-face consultation.

Evidence of Large Vestibulo-Ocular Reflex Reduction in Patients With Menière Attacks.

OBJECTIVE: To examine the high frequency horizontal vestibular ocular-reflex (hVOR) during acute attacks of vertigo in Menière's disease (MD). STUDY DESIGN: Retrospective case series and literature review. SETTING: Tertiary academic medical center. PATIENTS: Patients with clinical diagnosis of unilateral "definite MD." INTERVENTION: Review of medical records. MAIN OUTCOME MEASURES: Spontaneous nystagmus and the dynamic hVOR gain change at different stages of an acute episode of MD attack. RESULTS: We studied 10 vertigo attacks during the unique stages of the episode. During the acme stage of the attack, lower hVOR gain was recorded on the affected side (mean 0.48 ±â€Š0.23), which was associated with a paralytic nystagmus (beating away from the affected ear). Additionally, the mean hVOR gain remained significantly (p < 0.05) reduced during each of the other stages of the attack as compared with the unaffected side and a control group. After the attack, mean hVOR gains normalized in the affected ear. Mean hVOR gain of the unaffected ear remained normal during all stages. CONCLUSION: Vestibular function during an attack of MD is a dynamic process associated with fluctuation of the dynamic (hVOR gain) and static (spontaneous nystagmus) processes, which exist in parallel with the perception of vertigo. Our data support vHIT monitoring during an episode to provide objective and accurate evidence of the ear with active disease. This would be particularly useful for those patients with MD presentations of unreliable hearing or assisting to identify the ear to be treated in the case of bilateral MD.

Validation of the Argentine version of the Montreal Cognitive Assessment Test (MOCA): A screening tool for Mild Cognitive Impairment and Mild Dementia in Elderly.

The MoCA is a brief useful test to diagnose mild cognitive impairment (MCI) and mild dementia (MD). To date, no Argentine cross-cultural adapted validations of the Spanish version have been reported. OBJECTIVE: To validate the MoCA in the elderly and study its usefulness in MCI and MD. METHODS: This study included 399 individuals over 60 years old evaluated in the Cognitive-Behavioral Department (2017-2018). Patients with<3 years of education, sensory disturbances, psychiatric disorders, or moderate-severe dementia were excluded. The control group comprised cognitively normal subjects. Participants were classified according to neuropsychological assessment and clinical standard criteria into Control, MCI or MD groups. A locally adapted MoCA (MOCA-A) was administered to the patients and controls. RESULTS: Mean educational level was 10.34 years (SD 3.5 years). MoCA-A score differed significantly among groups (p<0.0001). MoCA-A performance correlated with educational level (r: 0.406 p<0.00001). Adopting a cut-off score ≥25 (YI=0.55), the sensitivity for MCI was 84.8% and for MD ​​100%, with specificity of 69.7%. When adding a single point to the score in patients with ≤12 years of education, the specificity of the test reached 81%. CONCLUSION: The MoCA-A is an accurate reliable screening test for MCI and MD in Argentina.

O MoCA é um teste breve e útil para diagnosticar comprometimento cognitivo leve (CCL) e demência leve. Até o momento, nenhuma validação argentina com adaptação transcultural da versão em espanhol havia sido relatada. OBJETIVO: Validar o MoCA em idosos e estudar sua utilidade no CCL e demência leve. MÉTODOS: Este estudo incluiu 399 indivíduos acima de 60 anos avaliados no departamento cognitivo-comportamental (2017-2018). Foram excluídos pacientes com menos de 3 anos de escolaridade, com distúrbios sensoriais, distúrbios psiquiátricos e demência moderada a grave. O grupo controle foi cognitivamente normal. Eles foram classificados de acordo com a avaliação neuropsicológica e os critérios clínicos padrão em Controles, MCI e demência leve. A versão adaptada do MoCA (MOCA-A) foi administrado aos pacientes e controles. RESULTADOS: Média de escolaridade: 10,34 anos (DP: 3,5). O escore MoCA-A foi significativamente diferente entre os grupos (p<0,0001). O MoCA-A correlacionou-se com a escolaridade (r=0,406 p<0,00001). Com uma pontuação de corte ≥25 (IY=0,55), a sensibilidade para CCL foi de 84,8% e para demência leve 100%, com especificidade de 69,7%. Adicionando um ponto único à pontuação em pacientes com menos de 12 anos de escolaridade, a especificidade do teste atingiu 81%. CONCLUSÃO: O MoCA-A é um teste de rastreamento preciso e confiável para MCI e demência leve na Argentina.

Validation of the Argentine version of the Montreal Cognitive Assessment Test (MOCA): A screening tool for Mild Cognitive Impairment and Mild Dementia in Elderly / Validação da versão argentina do teste montreal cognitive assessment test (moca): um instrumento de triagem para comprometimento cognitivo leve e demência leve em idosos

ABSTRACT. The MoCA is a brief useful test to diagnose mild cognitive impairment (MCI) and mild dementia (MD). To date, no Argentine cross-cultural adapted validations of the Spanish version have been reported. Objective: To validate the MoCA in the elderly and study its usefulness in MCI and MD. Methods: This study included 399 individuals over 60 years old evaluated in the Cognitive-Behavioral Department (2017-2018). Patients with<3 years of education, sensory disturbances, psychiatric disorders, or moderate-severe dementia were excluded. The control group comprised cognitively normal subjects. Participants were classified according to neuropsychological assessment and clinical standard criteria into Control, MCI or MD groups. A locally adapted MoCA (MOCA-A) was administered to the patients and controls. Results: Mean educational level was 10.34 years (SD 3.5 years). MoCA-A score differed significantly among groups (p<0.0001). MoCA-A performance correlated with educational level (r: 0.406 p<0.00001). Adopting a cut-off score ≥25 (YI=0.55), the sensitivity for MCI was 84.8% and for MD ​​100%, with specificity of 69.7%. When adding a single point to the score in patients with ≤12 years of education, the specificity of the test reached 81%. Conclusion: The MoCA-A is an accurate reliable screening test for MCI and MD in Argentina.

RESUMO. O MoCA é um teste breve e útil para diagnosticar comprometimento cognitivo leve (CCL) e demência leve. Até o momento, nenhuma validação argentina com adaptação transcultural da versão em espanhol havia sido relatada. Objetivo: Validar o MoCA em idosos e estudar sua utilidade no CCL e demência leve. Métodos: Este estudo incluiu 399 indivíduos acima de 60 anos avaliados no departamento cognitivo-comportamental (2017-2018). Foram excluídos pacientes com menos de 3 anos de escolaridade, com distúrbios sensoriais, distúrbios psiquiátricos e demência moderada a grave. O grupo controle foi cognitivamente normal. Eles foram classificados de acordo com a avaliação neuropsicológica e os critérios clínicos padrão em Controles, MCI e demência leve. A versão adaptada do MoCA (MOCA-A) foi administrado aos pacientes e controles. Resultados: Média de escolaridade: 10,34 anos (DP: 3,5). O escore MoCA-A foi significativamente diferente entre os grupos (p<0,0001). O MoCA-A correlacionou-se com a escolaridade (r=0,406 p<0,00001). Com uma pontuação de corte ≥25 (IY=0,55), a sensibilidade para CCL foi de 84,8% e para demência leve 100%, com especificidade de 69,7%. Adicionando um ponto único à pontuação em pacientes com menos de 12 anos de escolaridade, a especificidade do teste atingiu 81%. Conclusão: O MoCA-A é um teste de rastreamento preciso e confiável para MCI e demência leve na Argentina.

Is Cerebellar Ataxia, Neuropathy, and Vestibular Areflexia Syndrome (CANVAS) a Vestibular Ganglionopathy?

OBJECTIVES: CANVAS is an acronym for cerebellar ataxia, neuropathy and vestibular areflexia syndrome. Limited autopsy data has suggested that CANVAS is caused by a focal dorsal root ganglionopathy that damages Scarpa's (vestibular) ganglion, but spares the Spiral (hearing) ganglion. If the vestibular areflexia of CANVAS is in fact due to ganglionopathy, then there should be global reduction of all vestibular responses. MATERIALS AND METHODS: With this hypothesis in mind, a retrospective review of 5 subjects who met the clinical criteria for CANVAS was performed. Recent advances in vestibular testing have made it possible to quantify responses from all 5 vestibular end organs in the inner ear. Results of the Video head impulse test (VHIT), video oculography, caloric test and vestibular evoked myogenic potential (VEMP) were examined to determine if all 5 end organs are nonfunctional in CANVAS. RESULTS: Severe reduction of function of the six semicircular canals and ocular VEMPs were observed. Only the cervical VEMPs were present and reproducible, consistent with either partial sparing of the inferior vestibular ganglia, specific embryologic resistance of the saccule to the degeneration or a mechanism for cervical VEMPs that does not require an intact vestibular ganglion. CONCLUSION: Our results suggest that Scarpa´s ganglia dysfunction could be the mechanism for loss of semicircular canal and utricular function in CANVAS patients, but the preservation of the cervical VEMP response is unexplained.

Acute Bilateral Superior Branch Vestibular Neuropathy.

The rapid onset of a bilateral vestibular hypofunction (BVH) is often attributed to vestibular ototoxicity. However, without any prior exposure to ototoxins, the idiopathic form of BVH is most common. Although sequential bilateral vestibular neuritis (VN) is described as a cause of BVH, clinical evidence for simultaneous and acute onset bilateral VN is unknown. We describe a patient with an acute onset of severe gait ataxia and oscillopsia with features compatible with acute BVH putatively due to a bilateral VN, which we serially evaluated with clinical and laboratory vestibular function testing over the course of 1 year. Initially, bilateral superior and horizontal semicircular canals and bilateral utricles were impaired, consistent with damage to both superior branches of each vestibular nerve. Hearing was spared. Only modest results were obtained following 6 months of vestibular rehabilitation. At a 1-year follow-up, only the utricular function of one side recovered. This case is the first evidence supporting an acute presentation of bilateral VN as a cause for BVH, which would not have been observed without critical assessment of each of the 10 vestibular end organs.

Characteristics of vestibular corrective saccades in patients with slow visual saccades, vestibular disorders and controls: A descriptive analysis.

OBJECTIVE: Our aim was to determine whether overt catch up saccades (OS) provoked by vestibular stimuli, as observed in the video head impulse test (vHIT), have comparable metrics as visually triggered horizontal saccades (VS), indicating a common saccadic brainstem generator. METHODS: Three groups of patients were studied: patients with neurological disorders causing slow saccades (group 1, n = 12), patients with peripheral vestibular lesions (group 2, n = 43), and normal controls (group 3, = 24). All patients underwent vHIT and Videooculographic testing. OS velocity, acceleration, amplitude and duration and VS velocity in this group was compared between the groups. RESULTS: There was significant reduction in the velocity of visually guided saccades in group 1, as expected from the patient selection constraints of this study. Group 1 also exhibited saccades which were longer in duration and of reduced acceleration when compared to subjects without saccadic slowing to visual targets (Group 2 and 3). There were significant positive correlations between OS acceleration and amplitude in both normal saccade groups (2 and 3) which was not observed in the slow saccade group (1). CONCLUSIONS: The metrics of overt saccades measured by the vHIT in patients with slow saccades and normal controls are similar to visually guided saccades. This supports the hypothesis that overt saccades associated with vestibular stimuli and visually triggered saccades share common circuitry that controls metrics.

The Floccular Syndrome: Dynamic Changes in Eye Movements and Vestibulo-ocular Reflex in Isolated Infarction of the Cerebellar Flocculus.

The cerebellar flocculus is a critical structure involved in the control of eye movements. Both static and dynamic abnormalities of the vestibulo-ocular reflex (VOR) have been described in animals with experimental lesions of the flocculus/paraflocculus complex. In humans, lesions restricted to the flocculus are rare so they can become an exceptional model to contrast with the clinical features in experimental animals or in patients with more generalized cerebellar diseases. Here, we examined a 67-year-old patient with an acute vestibular syndrome due to an isolated infarct of the right flocculus. We evaluated him multiple times over 6 months-to follow the changes in eye movements and vestibular function-with caloric testing, video-oculography and head-impulse testing, and the anatomical changes on imaging. Acutely, he had an ipsilateral-beating spontaneous nystagmus, bilateral gaze-evoked nystagmus, borderline impaired smooth pursuit, and a complete contraversive ocular tilt reaction. The VOR gain was reduced for head impulses directed contralateral to the lesion, and there was also an ipsilesional caloric weakness. All abnormalities progressively improved at follow-up visits but with a considerable reduction in volume of the affected flocculus on imaging. The vestibular and ocular motor findings, qualitatively similar to a previously reported patient, further clarify the "acute floccular syndrome" in humans. We also add new information about the pattern of recovery from such a lesion with corresponding changes in the size of the affected flocculus on imaging.

Intra-Attack Vestibuloocular Reflex Changes in Ménière's Disease.

Ménière's attack has been shown to temporarily alter the vestibuloocular reflex (VOR). A patient with unilateral Ménière's disease was serially evaluated with the video Head Impulse Test during single, untreated episodes of acute vertigo. Spontaneous nystagmus activity was concurrently recorded in order to establish the three typical phases of Ménière's attack (irritative, paralytic, and recovery) and correlate them with VOR performance. The onset of attack was associated with a quick change in VOR gain on the side of the affected ear. While a rapidly progressive reduction of the VOR was evident at the paralytic nystagmus phase, in the recovery phase the VOR gain returned to normal and the direction of the previous nystagmus reversed. The membrane rupture potassium intoxication theory provides a good foundation with which to explain these dynamic VOR changes and the observed triphasic direction behavior of the spontaneous nystagmus. We additionally postulated that endolymphatic fluid displacement could have a synergic effect during the earliest phase of attack.