Assessment of otolith function using vestibular evoked myogenic potential in women during pregnancy / Avaliação da função otolítica através do potencial evocado miogênico vestibular em mulheres durante a gravidez

Abstract Introduction: More than 50% of pregnant women experience dizziness frequently in the first two gestational trimesters. During pregnancy, the changes in the metabolism of hormones are responsible for the ovarian cycle resulting in either peripheral or central vestibular alterations. The need for the study is to focus on the effect of changes during pregnancy on the vestibular evoked myogenic potential, an electrophysiological measure that investigates functions of the otolith structures. Objectives: The aim is to investigate the vestibular evoked myogenic potential responses during the first trimester of pregnancy. Methods: A total of 17 pregnant women and 17 non-pregnant women with age matched took part in this study. The cervical vestibular evoked myogenic potential were recorded from the ipsilateral sternocleridomastoid muscle and the ocular vestibular evoked myogenic potential were recorded from contralateral extraocular muscle in both groups. Results: Peak to peak amplitude of cervical vestibular evoked myogenic potential and ocular vestibular evoked myogenic potential was found to be significantly reduced in the responses obtained from first-trimester pregnant women when compared to that of non-pregnant women. Conclusions: Vestibular evoked myogenic potential tests exhibits a clinically significant reduced peak to peak amplitude in the first trimester of pregnancy, which indicates dysfunction in the otolith reflex pathway.

Resumo Introdução: Mais de 50% das mulheres grávidas apresentam tonturas frequentes nos primeiros dois trimestres da gravidez. Durante a gestação, as mudanças no metabolismo dos hormônios são responsáveis pelo ciclo ovariano, resultam em alterações vestibulares periféricas ou centrais. A necessidade do estudo é enfocar o efeito das mudanças durante a gravidez sobre o potencial evocado miogênico vestibular, uma medida eletrofisiológica que investiga as funções das estruturas otolíticas. Objetivo: Investigar as respostas do potencial evocado miogênico vestibular no primeiro trimestre da gravidez. Método: Participaram deste estudo 17 mulheres grávidas e 17 não grávidas com idades pareadas. O potencial evocado miogênico vestibular cervical foi registrado a partir do músculo esternocleidomastóideo ipsilateral e o potencial evocado miogênico vestibular ocular foi registrado a partir do músculo extraocular contralateral em ambos os grupos. Resultados: A amplitude pico a pico do potencial evocado miogênico vestibular cervical e do potencial evocado miogênico vestibular ocular estava significativamente reduzida nas respostas obtidas de mulheres grávidas no primeiro trimestre de gestação quando comparadas a de mulheres não grávidas. Conclusão: Os testes de potencial evocado miogênico vestibular mostram uma redução clinicamente significativa na amplitude pico a pico no primeiro trimestre da gravidez, o que indica disfunção na via otolítica reflexa.

Behavioural and objective vestibular assessment in persons with osteoporosis and osteopenia: a preliminary investigation / Behavioural and objective vestibular assessment in persons with osteoporosis and osteopenia: a preliminary investigation

Abstract Introduction: Calcium is vital for the functioning of the inner ear hair cells as well as for the neurotransmitter release that triggers the generation of a nerve impulse. A reduction in calcium level could therefore impair the peripheric vestibular functioning. However, the outcome of balance assessment has rarely been explored in cases with osteopenia and osteoporosis, the medical conditions associated with reduction in calcium levels. Objective: The present study aimed to investigate the impact of osteopenia and osteoporosis on the outcomes of behavioural and objective vestibular assessment tests. Methods: The study included 12 individuals each in the healthy control group and osteopenia group, and 11 individuals were included in the osteoporosis group. The groups were divided based on the findings of bone mineral density. All the participants underwent behavioural tests (Fukuda stepping, tandem gait and subjective visual vertical) and objective assessment using cervical and ocular vestibular evoked myogenic potentials. Results: A significantly higher proportion of the individuals in the two clinical groups' demonstrated abnormal results on the behavioural balance assessment tests (p < 0.05) than the control group. However, there was no significant difference in latencies or amplitude of cervical vestibular evoked myogenic potential and oVEMP between the groups. The proportion of individuals with absence of ocular vestibular evoked myogenic potential was significantly higher in the osteoporosis group than the other two groups (p < 0.05). Conclusion: The findings of the present study confirm the presence of balance-related deficits in individuals with osteopenia and osteoporosis. Hence the clinical evaluations should include balance assessment as a mandatory aspect of the overall audiological assessment of individuals with osteopenia and osteoporosis.

Resumo: Introdução: O cálcio é vital para o funcionamento das células ciliadas, assim como para a liberação dos neurotransmissores que desencadeiam um impulso nervoso. Uma redução nos níveis de cálcio poderia, portanto, prejudicar o funcionamento vestibular periférico. No entanto, a avaliação do equilíbrio tem sido raramente explorada em casos de osteopenia e osteoporose, condições médicas associadas à redução dos níveis de cálcio. Objetivo: O presente estudo teve como objetivo investigar o impacto da osteopenia e da osteoporose nos resultados dos testes de avaliação comportamental e vestibular objetiva. Método: O estudo incluiu 12 indivíduos nos grupos controle e grupo de osteopenia e 11 indivíduos no grupo da osteoporose. Os grupos foram divididos com base nos achados da densidade mineral óssea. Todos os participantes foram submetidos a testes comportamentais (Prova dos Passos de Fukuda, Marcha em tandem e Vertical Visual Subjetiva) e à avaliação objetiva com o uso de potenciais evocados miogênicos vestibulares cervical e ocular (cVEMP e oVEMP). Resultados: Uma proporção significativamente maior de indivíduos nos dois grupos com condições clínicas mostrou resultados anormais nos testes de avaliação comportamental e do equilíbrio (p < 0,05) do que o grupo controle. Embora não tenha havido diferença significativa nas latências ou na amplitude de cVEMP e oVEMP entre os grupos, a proporção de indivíduos com ausência de oVEMP foi significativamente maior no grupo da osteoporose do que nos outros dois grupos (p < 0,05). Conclusão: Os resultados do presente estudo demonstram a presença de déficits de equilíbrio em indivíduos com osteopenia e osteoporose. Assim, as avaliações clínicas gerais e audiológicas de indivíduos com osteopenia e osteoporose deveriam incluir a avaliação do equilíbrio como um aspecto obrigatório.

Effects of Gaze Positions on Ocular Vestibular Evoked Myogenic Potentials / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Recent works have demonstrated the existence of ocular vestibular evoked myogenic potentials (OVEMPs), which reflects otolith-ocular reflex. The purpose of this study was to identify an appropriate gaze position to detect OVEMPs produced by air-conducted sound stimulation in healthy subjects. SUBJECTS AND METHOD: Twenty four healthy subjects (35 ears) were included in this study. Surface electromyographic activity was recorded from active electrodes placed inferior to each eye. Stimulation with 500 Hz short tone bursts was used to activate the vestibular end-organs. RESULTS: Sound stimulation evoked negative-positive biphasic responses on both ipsilateral and contralateral eyes, while responses were contralateral eye-dominant. Contralateral eye responses had higher response incidence and larger amplitudes. Altering the direction of gaze generally changed the incidence and size of the inter-peak amplitudes. The higher incidence and larger amplitudes were recorded when the eyes are directed to the superior and ipsilateral side to the sound stimulation. In that gaze position, the amplitude was 5.3 micronV, the first negative peak latency was 10.5 ms and the following positive peak latency was 15.4 ms on the average. CONCLUSION: OVEMPs can be evoked using an air-conducted 500 Hz tone burst and are best recorded contralaterally with a upward gaze towards the source of sound stimulation. Further changes of the test parameters are needed for higher and consistent responses.