Potencial evocado miogênico vestibular (Vemp): avaliação das respostas em indivíduos normais

Abstract

Background: the Vestibular Evoked Myogenic Potential (Vemp) is formed by myogenic neurophysiologic responses activated by high-intensity sound stimulation. The response is registered through surface electromyography of the cervical muscles during muscle contraction. The acoustic stimuli activate the saccular macula, the vestibular inferior nerve and the pathways related to the vestibule-spinal descendant nerves. Aim: to describe Vemp parameters in a normal population. Methods: thirty adults, 13 men and 17 women with no otoneurological complaints were selected. The stimuli were 200 tone burst, with a frequency of 1Hz and intensity of 118 dB Na, band-pass filter ranging from 10Hz to 1500Hz. The first potential biphasic P13-N23 wave was analyzed. Results: no significant difference was observed between the sides of stimulation in terms of latency and amplitude. However, a statistically significant difference was found for amplitude between genders. Conclusion: Vemp demonstrated to be a reliable instrument in the clinical assessment of the vestibular function. Key Words: Vestibular Function Tests; Evaluation; Standards. ResumoTema: o Potencial Evocado Miogênico Vestibular (Vemp) é formado por respostas miogênicas ativadas por estimulação sonora de alta intensidade. Essas respostas são registradas por eletromiografia de superfície sobre a musculatura cervical na presença de contração muscular, ativando a mácula, o nervo vestibular inferior e as vias vestíbulo-espinhais descendentes. Objetivo: descrever as respostas evocadas do Vemp em uma população normal. Método: selecionaram-se 30 sujeitos adultos, sendo 13 homens e 17 mulheres, sem queixas otoneurológicas. Utilizou-se 200 estímulos tone burst com freqüência de 1Hz e intensidade de 118dB Na, filtro passa-banda de 10Hz a 1500Hz. Os traçados obtidos foram analisados em relação ao primeiro potencial bifásico composto por P13 e N23. Resultados: não houve diferença estatisticamente significativa entre o lado da estimulação em relação a latência e amplitude, porém foi encontrada diferença estatisticamente significativa em relação à amplitude do potencial entre os sexos. Conclusão: Vemp demonstrou ser uma ferramenta confiável na avaliação da função vestibular. Palavras-Chave: Vestibular; Potencial; Avaliação.

Potencial evocado miogênico vestibular cervical em crianças e adolescentes sem queixas vestibulares

“…In this study, the protocol that was used to perform cVEMP was based on other related studies that objectified standardize this test (2,3,9) . The positioning of the electrodes is one of the most frequently found methodological differences in the literature.…”

“…The positioning in the medial part of sternocleidomastoid muscle (13,14) used in this study was the most commonly used technique in the literature, with more consistent results, besides being comfortable for the patient (15,16,17) . Despite the various methods described in the literature for the activation of the sternocleidomastoid muscle (2,18,19,20,21) , the maximum lateral rotation of head with the seated individual was the method chosen in this research. This method is preferable for children and the elderly, due to the ease of staying in position without any major inconvenience (9,22) .…”

“…In this study, a tone burst of 500 Hz was used due to the more effective responses than click stimuli (16,18,23) . Frequencies equal or lower than 500 Hz are more commonly used and evoked homogeneous and reliable responses (2,14,23) .…”

“…The type of auditory stimuli used was the tone burst at a frequency of 500 Hz, intensity of 118 dBHL, with alternating polarity, a band-pass filter of 5-1000 Hz, 200 stimuli per second, and a noise limit of 90 to 100%. To perform the cVEMP, the patient was instructed to take the maximum lateral rotation of the head to the opposite side to the ear stimulated in order to capture the response of contraction muscle (2,3,9) . The database was made in Excel and analyzed by SPSS (Statistical Package for Social Sciences), version 20.0.…”

“…This response is activated by a sound stimulation in high intensity, which activates the saccular macula, the inferior vestibular nerve, and the vestibular-spinal tract descendants. The responses are recorded by the surface electrodes of the cervical muscles in contraction force and head rotation (2) . The assessment of diseases in the vestibular system in pediatric populations is important because changes in this system may involve several effects in the future, such as delayed in motor and learning development, interfering in language, writing, and reading skills.…”