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.

cVEMP correlated with imbalance in a mouse model of vestibular disorder

BACKGROUND@#Cervical vestibular evoked myogenic potential (cVEMP) testing is a strong tool that enables objective determination of balance functions in humans. However, it remains unknown whether cVEMP correctly expresses vestibular disorder in mice.@*OBJECTIVE@#In this study, correlations of cVEMP with scores for balance-related behavior tests including rotarod, beam, and air-righting reflex tests were determined in ICR mice with vestibular disorder induced by 3,3'-iminodipropiontrile (IDPN) as a mouse model of vestibular disorder.@*METHODS@#Male ICR mice at 4 weeks of age were orally administered IDPN in saline (28 mmol/kg body weight) once. Rotarod, beam crossing, and air-righting reflex tests were performed before and 3-4 days after oral exposure one time to IDPN to determine balance functions. The saccule and utricles were labeled with fluorescein phalloidin. cVEMP measurements were performed for mice in the control and IDPN groups. Finally, the correlations between the scores of behavior tests and the amplitude or latency of cVEMP were determined with Spearman's rank correlation coefficient. Two-tailed Student's t test and Welch's t test were used to determine a significant difference between the two groups. A difference with p < 0.05 was considered to indicate statistical significance.@*RESULTS@#After oral administration of IDPN at 28 mmol/kg, scores of the rotarod, beam, and air-righting reflex tests in the IDPN group were significantly lower than those in the control group. The numbers of hair cells in the saccule, utricle, and cupula were decreased in the IDPN group. cVEMP in the IDPN group was significantly decreased in amplitude and increased in latency compared to those in the control group. cVEMP amplitude had significant correlations with the numbers of hair cells as well as scores for all of the behavior tests in mice.@*CONCLUSIONS@#This study demonstrated impaired cVEMP and correlations of cVEMP with imbalance determined by behavior tests in a mouse model of vestibular disorder.

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 Plateau Time on Cervical Vestibular Evoked Myogenic Potential (cVEMP) elicited by 500-Hz Tone Burst / Jurnal Sains Kesihatan Malaysia

Cervical Vestibular Evoked Myogenic Potential (cVEMP) is a routine vestibular test which checks the integrity of vestibulocollic reflex (VCR) pathway. Clinically, 500-Hz tone burst is widely used stimulus to evoke a cVEMP. Although several studies have suggested different plateau times (PT) for eliciting cVEMPs, but not many have reported the optimal PT for evoking cVEMP using 500 Hz tone burst stimuli. Therefore, the present study aimed to investigate the effect of PT on cVEMPs elicited by 500 Hz tone burst at 95 dBnHL using four different PT (0, 2, 4 and 10 ms). Thirty healthy adults with normal hearing and vestibular systems participated in this study. Results revealed that the P1 latency was significantly longer for PT 10 ms compared to other PTs. N1 latency was significantly prolonged for long PT of 10 ms compared to PT 2 ms. P2 latency showed no significant differences among PTs. The P1-N1 inter-amplitude values however revealed no significant difference across all PTs. It was found that the P1-N1 inter-amplitude was severely affected after 4 ms of PT. This study concluded that the PT of either 0 or 2 ms yielded the most robust cVEMP.