RESUMO
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.
RESUMO
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 3â¯mA, duration 1â¯ms) was performed randomly on both ears of each participant. The participants between the ages of 18-65 (mean age 39.7⯱â¯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⯱â¯3.29â¯ms and 22.06⯱â¯3.95â¯ms, respectively. The P1-N1 amplitude value was 66.64⯱â¯24.5⯵V. The percentage of vestibular asymmetry was 16.29⯱â¯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.
Assuntos
Potenciais Evocados Miogênicos Vestibulares , Vestíbulo do Labirinto , Adolescente , Adulto , Idoso , Voluntários Saudáveis , Humanos , Pessoa de Meia-Idade , Potenciais Evocados Miogênicos Vestibulares/fisiologia , Vestíbulo do Labirinto/fisiologia , Adulto JovemRESUMO
Transcranial direct current stimulation (tDCS) is a re-emerging non-invasive brain stimulation technique that has been used in animal models and human trials aimed to elucidate neurophysiology and behavior interactions. It delivers subthreshold electrical currents to neuronal populations that shift resting membrane potential either toward depolarization or hyperpolarization, depending on stimulation parameters and neuronal orientation in relation to the induced electric field (EF). Although the resulting cerebral EFs are not strong enough to induce action potentials, spontaneous neuronal firing in response to inputs from other brain areas is influenced by tDCS. Additionally, tDCS induces plastic synaptic changes resembling long-term potentiation (LTP) or long-term depression (LTD) that outlast the period of stimulation. Such properties place tDCS as an appealing intervention for the treatment of diverse neuropsychiatric disorders. Although findings of clinical trials are preliminary for most studied conditions, there is already convincing evidence regarding its efficacy for unipolar depression. The main advantages of tDCS are the absence of serious or intolerable side effects and the portability of the devices, which might lead in the future to home-use applications and improved patient care. This chapter provides an up-to-date overview of a number tDCS relevant topics such as mechanisms of action, contemporary applications and safety. Furthermore, we propose ways to further develop tDCS research.