Inferior vestibular neuritis: 3 cases with clinical features of acute vestibular neuritis, normal calorics but indications of saccular failure

BACKGROUND: Vestibular neuritis (VN) is commonly diagnosed by demonstration of unilateral vestibular failure, as unilateral loss of caloric response. As this test reflects the function of the superior part of the vestibular nerve only, cases of pure inferior nerve neuritis will be lost. CASE PRESENTATIONS: We describe three patients with symptoms suggestive of VN, but normal calorics. All 3 had unilateral loss of vestibular evoked myogenic potential. A slight, asymptomatic position dependent nystagmus, with the pathological ear down, was observed. CONCLUSION: We believe that these patients suffer from pure inferior nerve vestibular neuritis

Peaks and Troughs of Three-Dimensional Vestibulo-ocular Reflex in Humans

The three-dimensional vestibulo-ocular reflex (3D VOR) ideally generates compensatory ocular rotations not only with a magnitude equal and opposite to the head rotation but also about an axis that is collinear with the head rotation axis. Vestibulo-ocular responses only partially fulfill this ideal behavior. Because animal studies have shown that vestibular stimulation about particular axes may lead to suboptimal compensatory responses, we investigated in healthy subjects the peaks and troughs in 3D VOR stabilization in terms of gain and alignment of the 3D vestibulo-ocular response. Six healthy upright sitting subjects underwent whole body small amplitude sinusoidal and constant acceleration transients delivered by a six-degree-of-freedom motion platform. Subjects were oscillated about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5° in azimuth. Transients were delivered in yaw, roll, and pitch and in the vertical canal planes. Eye movements were recorded in with 3D search coils. Eye coil signals were converted to rotation vectors, from which we calculated gain and misalignment. During horizontal axis stimulation, systematic deviations were found. In the light, misalignment of the 3D VOR had a maximum misalignment at about 45°. These deviations in misalignment can be explained by vector summation of the eye rotation components with a low gain for torsion and high gain for vertical. In the dark and in response to transients, gain of all components had lower values. Misalignment in darkness and for transients had different peaks and troughs than in the light: its minimum was during pitch axis stimulation and its maximum during roll axis stimulation. We show that the relatively large misalignment for roll in darkness is due to a horizontal eye movement component that is only present in darkness. In combination with the relatively low torsion gain, this horizontal component has a relative large effect on the alignment of the eye rotation axis with respect to the head rotation axis

Prevalence of Abnormalities in Vestibular Function and Balance among HIV-Seropositive and HIV-Seronegative Women and Men

BACKGROUND: Most HIV-seropositive subjects in western countries receive highly active antiretroviral therapy (HAART). Although many aspects of their health have been studied, little is known about their vestibular and balance function. The goals of this study were to determine the prevalences of vestibular and balance impairments among HIV-seropositive and comparable seronegative men and women and to determine if those groups differed. METHODS: Standard screening tests of vestibular and balance function, including head thrusts, Dix-Hallpike maneuvers, and Romberg balance tests on compliant foam were performed during semiannual study visits of participants who were enrolled in the Baltimore and Washington, D. C. sites of the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study. RESULTS: No significant differences by HIV status were found on most tests, but HIV-seropositive subjects who were using HAART had a lower frequency of abnormal Dix-Hallpike nystagmus than HIV-seronegative subjects. A significant number of nonclassical Dix-Hallpike responses were found. Age was associated with Romberg scores on foam with eyes closed. Sex was not associated with any of the test scores. CONCLUSION: These findings suggest that HAART-treated HIV infection has no harmful association with vestibular function in community-dwelling, ambulatory men and women. The association with age was expected, but the lack of association with sex was unexpected. The presence of nonclassical Dix-Hallpike responses might be consistent with central nervous system lesions

Agenesia e lipoma de corpo caloso: relato de caso

The agenesis and lipoma of the corpus callosum is a very rare association. We report the case of a 18-years old woman with rare epileptic seizures since the age of 6 years, normal neurological examination, as well as normal electroencephalogram. The brain computed tomography scanning and the magnetic resonance showed the lipoma and the agenesis of the corpus callosum.A agenesia e lipoma do corpo caloso é uma associação muito rara. Relatamos o caso de uma paciente de 18 anos com raras crises epilépticas desde os 6 anos de idade, exame neurológico normal, assim como eletrencefalograma normal. A tomografia computadorizada de crânio e a ressonância magnética mostraram o lipoma e a agenesia de corpo caloso.Escola Paulista de MedicinaUNIFESP, EPMSciEL

Direction-dependent excitatory and inhibitory ocular vestibular-evoked myogenic potentials (oVEMPs) produced by oppositely directed accelerations along the midsagittal axis of the head

Oppositely directed displacements of the head need oppositely directed vestibulo-ocular reflexes (VOR), i.e. compensatory responses. Ocular vestibular-evoked myogenic potentials (oVEMPs) mainly reflect the synchronous extraocular muscle activity involved in the process of generating the VOR. The oVEMPs recorded beneath the eyes when looking up represent electro-myographic responses mainly of the inferior oblique muscle. We aimed: (1) to study the properties of these responses as they were produced by head acceleration impulses to the forehead and to the back of the head; (2) to investigate the relationships between these responses and the 3-D linear head accelerations that might reflect the true stimulus that acts on the vestibular hair cells. We produced backward- and forward-directed acceleration stimuli in four conditions (positive and negative head acceleration impulses to the hairline and to the inion) in 16 normal subjects. The oVEMPs produced by backward- and forward-directed accelerations of the head showed consistent differences. They were opposite in the phase. The responses produced by backward accelerations of the head began with an initial negativity, n11; conversely, those produced by accelerations directed forward showed initially a positive response, p11. There was a high inter-subject correlation of head accelerations along the head anteroposterior and transverse axes, but almost no correlation of accelerations along the vertical axis of the head. We concluded that backward-directed head accelerations produced an initial excitatory response, and forward-directed accelerations of the head were accompanied by an initial inhibitory response. These responses showed dependence on acceleration direction in the horizontal plane of the head. This could be consistent with activation of the utricle

Vestibular evoked myogenic potential: recording methods in humans and guinea pigs

O potencial miogênico evocado vestibular (VEMP) é um teste clínico que avalia a função vestibular através de um reflexo vestíbulo-cervical inibitório captado nos músculos do corpo em resposta à estimulação acústica de alta intensidade. OBJETIVO: Verificar e analisar os diversos métodos de registro dos potenciais miogênicos evocados vestibulares no homem e em cobaias. MATERIAL E MÉTODO: Realizou-se busca eletrônica nas bases de dados MEDLINE, LILACS, SCIELO e COCHRANE. RESULTADOS: Foram verificadas divergências quanto às formas de registro dos potenciais miogênicos evocados vestibulares, relacionadas com os seguintes fatores: posição do paciente no momento do registro, tipo de estímulo sonoro utilizado (clicks ou tone bursts), parâmetros para a promediação dos estímulos (intensidade, freqüência, tempo de apresentação, filtros, ganho de amplificação das respostas e janelas para captação dos estímulos), tipo de fone utilizado e forma de apresentação dos estímulos (monoaural ou binaural, ipsi ou contralateral). CONCLUSÃO: Não existe consenso na literatura quanto ao melhor método de registro dos potenciais evocados miogênicos vestibulares, havendo necessidade de pesquisas mais específicas para comparação entre estes registros e a definição de um modelo padrão para a utilização na prática clínica

A brief review of the clinical anatomy of the vestibular-ocular connections—how much do we know?

This is an accepted manuscript of an article published by Springer Nature in Eye on 21/11/2014, available online: https://doi.org/10.1038/eye.2014.262 The accepted version of the publication may differ from the final published version.The basic connectivity from the vestibular labyrinth to the eye muscles (vestibular ocular reflex, VOR) has been elucidated in the past decade, and we summarise this in graphic format. We also review the concept of ‘velocity storage’, a brainstem integrator that prolongs vestibular responses. Finally, we present new discoveries of how complex visual stimuli, such as binocular rivalry, influence VOR processing. In contrast to the basic brainstem circuits, cortical vestibular circuits are far from being understood, but parietal-vestibular nuclei projections are likely to be involved