Role of cervical vestibular evoked myogenic potentials (cVEMP) and auditory brainstem response (ABR) in the evaluation of vestibular schwannoma / Papel dos potenciais evocados miogênicos vestibulares cervicais (cVEMP) e potencial evocado auditivo de tronco encefálico (PEATE) na avaliação do schwannoma vestibular

Abstract Introduction: Cervical vestibular evoked myogenic potentials (cVEMP) can assess the integrity of the inferior vestibular nerve thereby promising to be a useful tool in the audiological test battery to diagnose vestibular schwannoma. Objective: To ascertain the utility of cVEMP in diagnosis of vestibular schwannoma in conjunction with the ABR and to evaluate whether the size of lesion has any effect on the cVEMP measures. Methods: Case-files of 15 known cases of vestibular schwannoma whose pure tone audiometry, auditory brainstem response (ABR), cVEMP and radiological investigation findings were available, were included in the study. Patients were categorised as large or small tumours based on the size. The absolute and inter-peak latencies of ABR, amplitudes of waves V and I, and inter-aural latency difference of wave V of ABR; and latency of P1 and N1 of cVEMP and amplitude of P1-N1 complex were considered in the study. Results: There were eight large and nine small tumours. All the patients with large tumours showed significant severity of hearing loss whereas only three out of nine patients with small tumours showed severe to profound deafness in the affected ear. The rest showed hearing status ranging from normal hearing sensitivity to moderate hearing loss. Most of the patients with large tumours showed complete absence of ABR in the affected ears with no identifiable wave-peaks. ABR in small tumours exhibited delayed III-I and delayed V-I interpeak latency interval (IPL). Four out of five patients with large unilateral tumours revealed contralateral effects of reduced amplitude or absence of cVEMP. On the contrary, six out of eight unilateral small tumours showed a normal cVEMP response in the contralateral ear. Both the patients with NF2 in the present study demonstrated cVEMP abnormalities. Conclusion: ABR and cVEMP, when used in combination, can be of immense use in identification of neuro-otologic conditions such as vestibular schwannoma and bilateral tumours in NF2. In the evaluation of unilateral vestibular schwannoma, abnormal contralateral findings of cVEMP and ABR are strongly indicative of the tumour size >2.5 cm. In unilateral severe to profound loss wherein ABR in poorer ear cannot give information of site-of-lesion, cVEMP can help in the differentiation.

Resumo Introdução: Os potenciais evocados miogênicos vestibulares cervicais (cVEMP) podem avaliar a integridade do nervo vestibular inferior, prometem assim ser uma ferramenta útil na bateria de testes audiológicos para o diagnóstico de schwannoma vestibular. Objetivo: Determinar a utilidade de cVEMP no diagnóstico de schwannoma vestibular em conjunto com PEATE e avaliar se o tamanho da lesão tem qualquer efeito sobre as medidas do cVEMP. Método: Quinze casos diagnosticados com schwannoma vestibular cujos exames de audiometria tonal pura, potencial evocado auditivo de tronco encefálico (PEATE), cVEMP e investigação radiológica estavam disponíveis foram incluídos no estudo. Os pacientes foram classificados como portadores de tumores grandes ou pequenos. As latências absolutas e interpico de PEATE as amplitudes das ondas V e I e a diferença de latência interaural da onda V da PEATE e a latência de P1 e N1 de cVEMP e amplitude do complexo P1-N1 foram consideradas no estudo. Resultados: Havia oito tumores grandes e nove pequenos. Todos os pacientes com tumores grandes apresentavam perda auditiva grave enquanto apenas três dos nove pacientes com pequenos tumores apresentaram surdez grave a profunda na orelha acometida. O restante apresentou audição que variou de normal a perda auditiva moderada. A maioria dos pacientes com tumores grandes demonstrou ausência completa de PEATE nas orelhas acometidas sem picos de onda identificáveis. O PEATE em tumores pequenos apresentou intervalo de latência interpico (ILI) tardia III-I e tardia V-I. Quatro em cada cinco pacientes com tumores grandes unilaterais revelaram efeitos contralaterais de amplitude reduzida ou ausência de cVEMP. Ao contrário, seis dos oito tumores pequenos unilaterais apresentaram resposta de cVEMP normal na orelha contralateral. Ambos os pacientes com NF2 no presente estudo demonstraram anormalidades na cVEMP. Conclusão: PEATE e cVEMP, quando usadas em combinação, podem ser úteis na identificação de condições neuro-otológicas como schwannoma vestibular e tumores bilaterais em NF2. Na avaliação de schwannoma vestibular unilateral, achados contralaterais anormais de cVEMP e PEATE são fortemente indicativos de tumor >2,5 cm. Na perda unilateral grave a profunda, na qual o PEATE na orelha mais prejudicada não fornece informações do local da lesão, cVEMP pode ajudar na diferenciação.

Conditions of Cervical Vestibular Evoked Myogenic Potentials Test to Minimize Interaural Variation / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Cervical vestibular evoked myogenic potentials (cVEMP) test has been widely used to assess the function of the saccule and inferior vestibular nerve. Electrode location and stimulating sound are important factors which might affect the test results. Today those parameters are usually selected to maximize the waveform response. In this study, we tried to find the optimal condition to minimize the range of normal value of cVEMP. SUBJECTS AND METHOD: Thirteen normal subjects (26 ears) were included. We placed electrodes at five different locations over the sternocleidomastoid muscle (SCM) and used four different stimulation sounds. Variances of parameters, including interpeak amplitude, interaural difference (IAD) and normal value were analyzed and compared. RESULTS: When using the classical condition (mid point of SCM and 500 Hz) without rectification, IAD ratio was 20.8+/-14.2% and the range of normal value was 39%. When we used 2000 Hz tone burst sound at the classical electrodes site, IAD ratio and normal value were minimized, resulting in 18.7+/-14.3% and 31% respectively. After the rectification, when using the classical condition, IAD ratio was 26.4+/-22.3% and the range of normal value was 49%. The minimum IAD ratio was measured as 17.4+/-13.7% when we used click sound at SCM at the level of mandibular angle. And the minimum normal value of 32% was measured when we used 1000 Hz tone burst sound at SCM at the level of mandibular angle. CONCLUSION: Although the condition was not optimal for maximizing the interpeak amplitude, we could alternatively use the condition to minimize the normal value.

Cervical Vestibular Evoked Myogenic Potential and Ocular Vestibular Evoked Myogenic Potential in Patients With Vestibular Neuritis and Acute Viral Labyrinthitis / 대한평형의학회지

BACKGROUND AND OBJECTIVES: Vestibular neuritis predominantly affects the superior branch of the vestibular nerve, resulting in vertigo. Acute viral labyrinthitis occurs when an infection affects both vestibulo-cochlear nerve and labyrinth, resulting in hearing changes as well as vertigo. The purpose of study is to identify there is a difference of cervical vestibular evoked myogenic potentials (cVEMP) and ocular VEMP (oVEMP) in patients with vestibular neuritis and acute viral labyrinthitis. MATERIALS AND METHODS: cVEMP and oVEMP tests using 500-Hz tone-burst stimuli were performed on patients with vestibular neuritis and acute viral labyrinthitis. Pure tone audiometry, caloric test and subjective visual vertical (SVV) were performed in all patients. We compared the VEMP results, SVV, caloric test in patients with vestibular neuritis and acute viral labyrinthitis. RESULTS: Abnormal cVEMP responses were detected in 2 (20%) patients with vestibular neuritis and 5 (100%) patients with labyrinthitis. Abnormal oVEMP responses were detected in 9 patients (90%) with vestibular neuritis and 5 (100%) patients with labyrinthitis. oVEMP abnormalities is correlated with caloric test and subjective visual vertical in patients with vestibular neuritis and labyrinthits. CONCLUSION: Our results shows that the response of cVEMP and oVEMP between patients with vestibular neuritis and acute viral labyrinthitis is different. We can infer that oVEMP response to air-conducted sound is different vestibular origin compared to cVEMP and may originate from utricle.

Cervical Vestibular-Evoked Myogenic Potentials Using Vibration and Sound in Normal Subjects / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate and compare the incidence and the characteristics of parameters of cervical vestibular-evoked myogenic potentials (cVEMPs) using air-conducted (AC) and bone-conducted (BC) stimulations in normal subjects. SUBJECTS AND METHOD: Twenty-four normal subjects (48 ears) with normal hearing and no previous history of dizziness were included. cVEMP responses were recorded by surface electrodes on sternocleidomastiod muscles in response to AC and BC stimuli sequentially. Variances of parameters, including thresholds, amplitudes and interaural amplitude difference ratios (IADR), were analyzed and compared. RESULTS: cVEMP responses were clearly observed in all 48 ears in both AC and BC cVEMP tests. There was no significant difference in latencies (p1 and n1). However, the thresholds in BC cVEMP testing were significantly lower than those in AC cVEMP testing, when compared to the maximum stimulation level. Interaural amplitude difference ratios showed no significant difference in between the two tests, although amplitudes at maximum stimulation intensity in BC cVEMP testing were significantly larger than those in AC cVEMP testing. CONCLUSION: This study shows that BC cVEMP testing shows lower thresholds compared to AC cVEMP testing in normal subjects, suggesting that the threshold value can be used as a parameter in detecting vestibular dysfunction in the clinic. Further studies in patients with various vestibular disorders are needed.