Galvanic vestibular evoked myogenic potentials: normative data and the effect of age / Potenciais evocados miogênicos vestibulares galvânicos: dados normativos e o efeito da idade

Abstract Introduction: Galvanic vestibular evoked myogenic potentials evaluate vestibular nerve responses using electric stimulation by records collected from the sternocleidomastoid muscle. A normal vestibular evoked myogenic potential response consists of the first positive, P1, and negative, N1, peaks. The response can be affected by factors such as age and gender and is also consequential in the diagnosis of pathologies. Objectives: The present study was performed to obtain normative data on healthy adults, to help in diagnosis by establishing clinical norms as well as to investigate changing test parameters with age in galvanic vestibular evoked myogenic potentials. Methods: A total of 100 healthy participants were included in the study. Galvanic vestibular evoked myogenic potential (current 3 mA, duration 1ms) was performed randomly on both ears of each participant. The participants between the ages of 18-65 (mean age 39.7 ± 13.9) were divided into 5 groups according to their ages. Normative data of galvanic vestibular evoked myogenic potentials parameters were calculated in groups and in total, and age-related changes were examined. Results: The galvanic vestibular evoked myogenic potential waveform was elicited from all participants (200 ears). The latency of P1 and N1 was 7.82 ± 3.29ms and 22.06 ± 3.95 ms, respectively. The P1-N1 amplitude value was 66.64 ± 24.5 μV. The percentage of vestibular asymmetry was 16.29 ±11.99%. The latencies of P1 and N1 and P1-N1 amplitude values demonstrated significant differences among different age groups (p < 0.01). Conclusions: The results of this study show that as age increased, latencies were prolonged, and amplitudes gradually decreased. The normative data aids in the diagnosis of retrolabyrinthine lesions and the increase in the clinical use of galvanic vestibular evoked myogenic potentials.

Resumo Introdução: Os potenciais evocados miogênicos vestibulares galvânicos avaliam as respostas do nervo vestibular com estimulação elétrica por meio de registros coletados do músculo esternocleidomastóideo. Uma resposta normal de potenciais evocados miogênicos vestibulares consiste nos primeiros picos positivo, P1, e negativo, N1. A resposta pode ser afetada por fatores como idade e sexo e também tem importância no diagnóstico de doenças. Objetivos: Obter dados normativos em adultos saudáveis, para ajudar no diagnóstico através do estabelecimento de normas clínicas, e investigar a alteração dos parâmetros de teste com a idade em potenciais evocados miogênicos vestibulares galvânicos. Método: Foram incluídos no estudo 100 participantes saudáveis. O potencial evocado miogênico vestibular galvânico (corrente 3mA, duração 1ms) foi realizado de forma aleatória nas duas orelhas de cada participante. Os participantes entre 18 e 65 anos (média de 39,7 ±13,9) foram divididos em 5 grupos de acordo com a idade. Os dados normativos dos parâmetros dos potenciais evocados miogênicos vestibulares galvânicos foram calculados nos grupos e no total e as alterações relacionadas à idade foram examinadas. Resultados: A forma de onda do potencial evocado miogênico vestibular galvânico foi obtida de todos os participantes (200 orelhas). A latência de P1 e N1 foi de 7,82±3,29ms e 22,06 ±3,95 ms, respectivamente. O valor da amplitude P1-N1 foi de 66,64 ±24,5 μV. O percentual de assimetria vestibular foi de 16,29± 11,99%. Os valores das latências de P1 e N1 e da amplitude P1-N1 mostraram diferenças significantes entre os diferentes grupos etários (p < 0,01). Conclusão: Os resultados deste estudo mostram que à medida que a idade aumentou as latências foram prolongadas e as amplitudes diminuíram gradualmente. Os dados normativos auxiliam no diagnóstico de lesões retrolabirínticas e na disseminação do uso clínico dos potenciais evocados miogênicos vestibulares galvânicos.

Effects of Galvanic Stimulation on Spontaneous Nystagmus in Meniere's Disease and Vestibular Neuritis: A Preliminary Study / 대한평형의학회지

BACKGROUND AND OBJECTIVES: Galvanic vestibular stimulation (GVS) is known to induce nystagmus, ocular torsion, a tilt of subjective visual vertical, and perceptual and postural shift. The aim of this study was to compare the findings of GVS among the patients with spontaneous nystagmus (SN) caused by Meniere's disease (MD) or vestibular neuritis (VN). MATERIALS AND METHODS: Three-dimensional video-oculography was performed without fixation in 4 patients with MD and 2 with VN, as diagnosed by history, independent vestibular function tests and neuroimaging. We recorded the eye-movements in response to bilateral, bipolar, and surface GVS (2.5~3 mA) for 30 seconds, and analyzed mean slow phase velocity of SN. RESULTS: Of the 4 patients with MD, two exhibited a suppression of the left beating SN during anode stimulation of left mastoid and an augmentation of the nystagmus during cathode stimulation of left mastoid. The same patterns of galvanic modulation were observed in the other 2 patients with right beating SN due to MD. In contrast, the patients with VN showed an absent or decreased response to GVS. CONCLUSION: In MD, the responses to GVS were preserved while the responses were impaired in VN. These results suggest that the irregular vestibular fibers, which are sensitive to GVS, are relatively spared in MD. In contrast, both regular and irregular fibers appear to be damaged in VN. GVS may be helpful in discriminating MD from VN, especially when the patients presented without auditory symptoms.

The study of galvanic vestibular stimulation in patients of total unilateral vestibular loss

OBJECTIVES: The aim of this study was to observe the nystagmus of totally unilateral vestibular function loss on galvanic vestibular stimulation and the diagnostic value of galvanic vestibular stimulation. Additionally we wanted to evaluate which portions may be stimulated by galvanic vestibular stimulation. MATERIALS AND METHODS: We evaluated the three parameters of galvanic stimulation in fourteen patients with totally unilateral vestibular function loss, 1)spontaneous nystagmus, 2)galvanic stimulating nystagmus, 3)Post galvanic stimulating nystagmus through 3-dimensional video-oculography technique. RESULTS: When negative electrode was attached to the intact side, The nystagmus on galvanic vestibular stimulation was directed to the negative electrode side in all patients and post galvanic stimulating nystagmus was directed to the opposite side but on functional loss side, we couldn't detect any nystagmus on galvanic vestibular stimulation and in 10 patients, post galvanic stimulating nystagmus was observed and directed to the intact side. CONCLUSIONS: Galvanic vestibular stimulation is very useful for evaluating the vestibular function and for diagnosing the vestibular disease.