• Annals of Clinical Neurophysiology
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• v.22 no.2
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• pp.67-74
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• 2020

Vestibular-evoked myogenic potentials (VEMPs) are useful for evaluating the vestibulocollic reflex arising mostly from the saccule and the vestibuloocular reflex originating from the utricle. VEMPs can vary with the characteristics of the applied stimuli and the effects of aging and diseases. VEMPs have been found to be useful for diagnosing superior canal dehiscence, but their usefulness for other clinical disorders remains unclear. This review discusses the principles of VEMP tests and summarizes the findings for VEMPs in common vestibular disorders.

• Annals of Clinical Neurophysiology
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• v.7 no.1
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• pp.1-6
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• 2005

Loud click or tone burst sound can activate vestibular receptor and evoke reflex changes in tonic electromyographic activity within the stenocleidomastoid muscles. This reflex is assumed to originate in the saccule, the afferent pathways being the inferior vestibular nerve, and the efferent pathways the vestibulospinal tract. Averaging these muscular responses allows vestibular evoked myogenic potentials (VEMP) to be obtained. The earliest response ipsilateral to a loud click, p13n23, is dependent upon vestibular activation, specifically saccular afferents. These new techniques are beginning to be applied clinically in the patient of vestibular neuritis, Meniere's disease, acoustic neuromas, Tullio phenomenon, etc. VEMP recording will provide both a straightforward non-invasive exploration of each vestibule independently and an attractive method by which to explore otolithic receptors and vestibulospinal pathways.

• Annals of Clinical Neurophysiology
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• v.12 no.2
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• pp.35-46
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• 2010

Various electrophysiological tests have provided a large body of valuable information on neuronal responses to a presented stimulus. The special and general somatic sensory pathways are main targets of evoked potentials. Two types of evoked potentials, exogenous and endogenous, are commonly used. Exogenous evoked potentials of general and special somatic sensory systems will be reviewed. One of general somatic sensory functional pathways, proprioception, can be evaluated by general somatosensory evoked potentials with electrical stimulation on nerves. The special somatosensory functional pathways, including vision, and audition, can be evaluated by visual evoked potentials and auditory evoked potentials. Also laser-evoked potentials are newly developed for pain pathway, including lateral spinothalamic pathway, and vestibular myogenic evoked potentials for sacculocollic pathways. The evoked potentials of sensory system have maximal clinical utility in evaluating functional deficits along the sensory pathways. They are used for evaluating comatose patients, hysterical patients, premature infants, patients with suspected demyelinating diseases or neoplasms, and research. We discuss the neurophysiologic tests of sensory systems in views of practical points. The organized evaluation of sensory electrophysiologic tests can be helpful in detecting and estimating the abnormalities in neurological diseases.

• Annals of Clinical Neurophysiology
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• v.8 no.1
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• pp.53-57
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• 2006

Background: Vstibular evoked myogenic potentials(VEMP) have been known to be useful documenting abnormality in patients with various vestibular disorders and brainstem lesions but the studies of VEMP in patients with hemispheric lesions are rare. Methods: We recorded VEMP in 21 consecutive patients with acute ischemic stroke in the supratentorial lesions without evidence of brainstem or vestibular end organ lesions. All patients underwent magnetic resonance imaging and the main outcome measures of VEMP were recorded in all subjects. We interpreted each parameters of VEMP using our normal laboratory data. Results: VEMP abnormalities(prolonged latency or asymmetry of amplitude) were found in 57%(12/21) of acute infarction patients with supratentorial lesions. Bilateral VEMP abnormalities were found in six patients and unilateral abnormalities were found in another six patients with ipsilateral abnormalities in the three and controlateral abnormalities in the three patients. Conclusions: VEMP abnormalities were found in supratentorial stroke patients in our studies and this findings suggest supranuclear control may affect the generation of VEMP potentials.

• Journal of Audiology & Otology
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• v.24 no.1
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• pp.10-16
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• 2020

Background and Objectives:The blockage of adenosine receptors by caffeine changes the levels of neurotransmitters. These receptors are present in all parts of the body, including the auditory and vestibular systems. This study aimed to evaluate the effect of caffeine on evoked potentials using auditory brainstem responses (ABRs) and cervical vestibular-evoked myogenic potentials (cVEMPs) in a double-blind placebo-controlled study. Subjects and Methods: Forty individuals (20 females and 20 males; aged 18-25 years) were randomly assigned to two groups: the test group (consuming 3 mg/kg pure caffeine powder with little sugar and dry milk in 100 mL of water), and the placebo group (consuming only sugar and dry milk in 100 mL water as placebo). The cVEMPs and ABRs were recorded before and after caffeine or placebo intake. Results: A significant difference was observed in the absolute latencies of I and III (p<0.010), and V (p<0.001) and in the inter-peak latencies of III-V and I-V (p<0.001) of ABRs wave. In contrast, no significant difference was found in cVEMP parameters (P13 and N23 latency, threshold, P13-N23 amplitude, and amplitude ratio). The mean amplitudes of P13-N23 showed an increase after caffeine ingestion. However, this was not significant compared with the placebo group (p>0.050). Conclusions: It seems that the extent of caffeine's effects varies for differently evoked potentials. Latency reduction in ABRs indicates that caffeine improves transmission in the central brain auditory pathways. However, different effects of caffeine on auditory- and vestibular-evoked potentials could be attributed to the differences in sensitivities of the ABR and cVEMP tests.

• Korean Journal of Audiology
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• v.24 no.1
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• pp.10-16
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• 2020

Background and Objectives:The blockage of adenosine receptors by caffeine changes the levels of neurotransmitters. These receptors are present in all parts of the body, including the auditory and vestibular systems. This study aimed to evaluate the effect of caffeine on evoked potentials using auditory brainstem responses (ABRs) and cervical vestibular-evoked myogenic potentials (cVEMPs) in a double-blind placebo-controlled study. Subjects and Methods: Forty individuals (20 females and 20 males; aged 18-25 years) were randomly assigned to two groups: the test group (consuming 3 mg/kg pure caffeine powder with little sugar and dry milk in 100 mL of water), and the placebo group (consuming only sugar and dry milk in 100 mL water as placebo). The cVEMPs and ABRs were recorded before and after caffeine or placebo intake. Results: A significant difference was observed in the absolute latencies of I and III (p<0.010), and V (p<0.001) and in the inter-peak latencies of III-V and I-V (p<0.001) of ABRs wave. In contrast, no significant difference was found in cVEMP parameters (P13 and N23 latency, threshold, P13-N23 amplitude, and amplitude ratio). The mean amplitudes of P13-N23 showed an increase after caffeine ingestion. However, this was not significant compared with the placebo group (p>0.050). Conclusions: It seems that the extent of caffeine's effects varies for differently evoked potentials. Latency reduction in ABRs indicates that caffeine improves transmission in the central brain auditory pathways. However, different effects of caffeine on auditory- and vestibular-evoked potentials could be attributed to the differences in sensitivities of the ABR and cVEMP tests.

• Korean Journal of Clinical Laboratory Science
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• v.39 no.2
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• pp.136-140
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• 2007

The aim of this study was to examine the effect of differences in age and sex on vestibular evoked myogenic potentials (VEMP), particularly in normal participants. Briefly, the VEMP is a response elicited by loud clicks or tone bursts recorded from the tonically contracted sternocleidomastoid muscle. A total of 72 participants were divided into 6 groups according to their age and sex (20~30/F, 20~30/M, 40~50/F, 40~50/M, ${\geq}60/F$, ${\geq}60/M$). We got the data of latency, amplitude, and asymmetry index of the amplitude(ASI) from them. As a result of this study, there are variations in VEMP amplitudes and ASI depending on the muscle tension and the intensity of stimuli. In contrast, the latency of the response is usually less varied and does not differ significantly.

• Journal of Audiology & Otology
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• v.25 no.2
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• pp.98-103
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• 2021

Background and Objectives: The aim of the study was to compare effects of tone-burst (TB) and narrow-band (NB) Claus Elberling (CE)-chirp stimuli on amplitude, latency and interaural asymmetry ratio (IAR) of cervical vestibular evoked myogenic potentials (cVEMP) in healthy individuals. Subjects and Methods: The study included 50 healthy volunteers. cVEMP procedure was carried out using 500 Hz TB and NB-CE-chirp stimulus (360-720 Hz, up-chirp) in random order. cVEMP were recorded at 100 dB nHL. For each ear and each stimulus, P1 latency, N1 latency and P1N1 amplitude were measured. IAR was also calculated. Results: Mean age was 26.66±9.48 years. cVEMP's in response to both TB and NB CE-chirp stimuli were obtained in all subjects. No statistically significant difference in P1 latency, N1 latency, and P1N1 amplitude was found between the right and left ears for both TB and NB CE-chirp stimuli (p>0.05). In both sides, P1 and N1 latencies were significantly shorter in NB CE-chirp stimulation compared to TB stimulation (p=0.000). In both sides, no statistically significant difference was found in P1N1 amplitude between two types of stimuli (p>0.05). Conclusions: The chirp stimulus produces robust but earlier cVEMP than TB does. This largest series study on NB chirp cVEMP shows that NB chirp is a good and new reliable alternative.

• Korean Journal of Audiology
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• v.25 no.2
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• pp.98-103
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• 2021

Background and Objectives: The aim of the study was to compare effects of tone-burst (TB) and narrow-band (NB) Claus Elberling (CE)-chirp stimuli on amplitude, latency and interaural asymmetry ratio (IAR) of cervical vestibular evoked myogenic potentials (cVEMP) in healthy individuals. Subjects and Methods: The study included 50 healthy volunteers. cVEMP procedure was carried out using 500 Hz TB and NB-CE-chirp stimulus (360-720 Hz, up-chirp) in random order. cVEMP were recorded at 100 dB nHL. For each ear and each stimulus, P1 latency, N1 latency and P1N1 amplitude were measured. IAR was also calculated. Results: Mean age was 26.66±9.48 years. cVEMP's in response to both TB and NB CE-chirp stimuli were obtained in all subjects. No statistically significant difference in P1 latency, N1 latency, and P1N1 amplitude was found between the right and left ears for both TB and NB CE-chirp stimuli (p>0.05). In both sides, P1 and N1 latencies were significantly shorter in NB CE-chirp stimulation compared to TB stimulation (p=0.000). In both sides, no statistically significant difference was found in P1N1 amplitude between two types of stimuli (p>0.05). Conclusions: The chirp stimulus produces robust but earlier cVEMP than TB does. This largest series study on NB chirp cVEMP shows that NB chirp is a good and new reliable alternative.

• Annals of Clinical Neurophysiology
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• v.7 no.2
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• pp.75-79
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• 2005

Vestibular evoked myogenic potentials (VEMP) have been known to useful in documenting abnormality in patients with various vestibular disorders but the studies of VEMP in stroke patients are rare. We recorded VEMP in 17 consecutive patients with acute ischemic stroke in the brainstem lesions. All patients underwent magnetic resonance imaging and we compare VEMP results with the lesion documented by brain imaging. VEMP were defined to be abnormal when they were very asymmetrical (one is 2 times of more as large as the other), or absent in one side. VEMP abnormalities were found in 71%(12/17) of acute infarction patients with brainstem lesions. Most abnormalities found in the ipsilateral side of the lesion(9/12) but abnormalities in contralateral side of lesion were found in 25%(3/12) of patients.VEMP would be considered a useful complementary neurophysiological tool for the evaluation of brainstem dysfunction in acute stroke patients.