cVEMP Tests Research Articles

Correlating vestibular schwannoma size with vestibular-evoked myogenic potential results.

The maximum size of the vestibular schwannoma (VS) that is compatible with preservation of the function of the vestibular nerve in performing stereotactic radiosurgery remains unclear. This study utilized ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) test results to correlate with the size of VS. Fifty patients with unilateral VS underwent audiometry, and caloric, oVEMP and cVEMP tests. Tumor size from magnetic resonance imaging was measured on the axial plane, and the relationships between tumor size and each test result were analyzed. The pure-tone average from four frequencies did not significantly predict tumor size. Alternatively, oVEMP and cVEMP responses remained significant predictors for tumor size in the regression model, namely, tumor size (cm) = 0.62 × (oVEMP response) + 1.39 × (cVEMP response), where oVEMP and cVEMP responses were regarded as binary variables, in which 1 and 0 reflect abnormal and normal responses, respectively. This model explained 76% of the variance. Accordingly, the estimated VS size exhibiting abnormal oVEMPs and cVEMPs is >2.01 (0.62 +1.39) cm. When VS size is <2.0 cm, preservation of the function of superior/inferior vestibular nerve indicated by the oVEMP/cVEMP test is achievable. Therefore, both oVEMP and cVEMP tests may serve as supplementary tools for determining treatment option in VS patients.

Assessment of Ocular and Cervical Vestibular‐Evoked Myogenic Potentials in Cisptin‐Induced Otolith Toxicity in Guinea Pigs

Objectives: (1) Determine if cervical vestibular evoked myogenic potentials (cVEMPs) and ocular vestibular evoked myogenic potentials oVEMPs are good electrophysiological examinations to represent the degree of cisplatin-induced otolith toxicity. (2) Examine if D-methionine (D-met) pre-injection protects the otolith organs against cisplatin-induced changes of enzyme activities and oxidative status. Methods: Guinea pigs were intraperitoneally injected with sterile 0.9% saline alone, cisplatin (5 mg/kg) alone, D-met (300 mg/kg) alone, or D-met (300 mg/kg) 30 minutes before cisplatin (5 mg/kg) in combination, once daily for 7 consecutive days. Each animal was given the oVEMP and cVEMP tests before and after treatment. Changes in otolithic biochemistry, including membranous Na+, K+-ATPase, and Ca2+-ATPase, lipid peroxidation (LPO), and nitric oxide (NO), were also evaluated. Results: In the cisplatin-treated guinea pigs, the mean amplitudes of cVEMP and oVEMP tests were significantly ( P’s &lt; .05) decreased in comparison with the other 3 groups. In guinea pigs receiving both D-met and cisplatin, their amplitudes of cVEMP and oVEMP tests were significantly larger ( P &lt; .05) than those of the cisplatin group, but smaller ( P &lt; .05) than those of the saline or D-met group. In comparison with the other 3 groups, cisplatin alone group had the lowest ( P &lt; .05) mean Na+, K+-ATPase, and Ca2+-ATPase, and the highest ( P &lt; .05) LPO and NO levels. Conclusions: The cVEMP and oVEMP tests were feasible for the evaluation of cisplatin-related otolith dysfunction. The D-met–mediated improvement in otolith function correlated with a significant attenuation of increased oxidative stress and reduced ATPase activities.

Vestibular Testing Data in Migraine‐Associated Vertigo

Objectives: (1) Describe data on comprehensive vestibular testing in migraine-associated vertigo patients. (2) Delineate specific findings in vestibular testing that can assist in the diagnosis and treatment of migraine-associated vertigo. Methods: A retrospective case review of individuals diagnosed with migraine-associated vertigo after evaluation by an otologist, a neurologist, and who had vestibular testing between January 1, 2010, and June 31, 2012, at a tertiary referral center. Videonystagmography (VNG), sinusoidal harmonic acceleration (SHA) testing, and cervical vestibular evoked myogenic potential (cVEMP) testing were analyzed. Results: Eighty-three patients met inclusion criteria; 63 had a diagnosis of primary migraine-associated vertigo. An additional 20 patients had a secondary diagnosis including Ménières disease, intracranial hypertension, and a history of cranial surgery (secondary migraine-associated vertigo). The average patient was 49 years old, with 82% being female. There was no statistically significant difference between the 2 groups. Overall, 30% of migraine-associated vertigo patients had abnormal caloric testing with a 60% average unilateral weakness. The unilateral weakness was to the right 77% of the time. When VNG, SHA, and cVEMP testing were combined, 24 patients (29%) had an identifiable vestibular weakness; 75% had a peripheral source and 25% had central vestibular findings. A total of 50% of patients with a peripheral weakness were fully compensated, 33% were partially compensated, and 17% were poorly compensated. Conclusions: In patients with primary and secondary migraine-associated vertigo, approximately two-thirds of patients were found to have normal vestibular testing. When there was an identifiable vestibular weakness, 75% were peripheral with only 50% fully compensated.

Normalization Reduces Intersubject Variability in Cervical Vestibular Evoked Myogenic Potentials

Cervical vestibular evoked myogenic potentials are used to assess saccular and inferior vestibular nerve function. Normalization of the VEMP waveform has been proposed to reduce the variability in vestibular evoked myogenic potentials by correcting for muscle activation. In this study, we test the hypothesis that normalization of the raw cervical VEMP waveform causes a significant decrease in the intersubject variability. Prospective cohort study. Large specialty hospital, department of otolaryngology. Twenty healthy subjects were used in this study. All subjects underwent cervical vestibular evoked myogenic potential testing using short tone bursts at 250, 500, 750, and 1,000 Hz. Both intersubject and intrasubject variability was assessed. Variability between raw and normalized peak-to-peak amplitudes was compared using the coefficient of variation. Intrasubject variability was assessed using the intraclass correlation coefficient and interaural asymmetry ratio. cVEMPs were present in most ears. Highest peak-to-peak amplitudes were recorded at 750 Hz. Normalization did not alter cVEMP tuning characteristics. Normalization of the cVEMP response caused a significant reduction in intersubject variability of the peak-to-peak amplitude. No significant change was seen in the intrasubject variability. Normalization significantly reduces cVEMP intersubject variability in healthy subjects without altering cVEMP characteristics. By reducing cVEMP amplitude variation due to nonsaccular, muscle-related factors, cVEMP normalization is expected to improve the ability to distinguish between healthy and pathologic responses in the clinical application of cVEMP testing.

Involvement of vestibular organs in idiopathic sudden hearing loss with vertigo: An analysis using oVEMP and cVEMP testing

ObjectiveTo investigate the extent of vestibular lesions in idiopathic sudden hearing loss (ISHL) with vertigo. MethodWe reviewed the clinical records of 25 consecutive new patients with ISHL with vertigo. We classified patients based on their pattern of vestibular dysfunction. All patients showed cochlear damage and were labeled C (cochlear) type. If a patient showed abnormal cervical vestibular evoked myogenic potential (cVEMP), ocular VEMP (oVEMP) or caloric responses, an S (saccule), U (utricule) or L (lateral semicircular canal) respectively was added to their label. ResultsAll patients underwent cVEMPs and caloric tests. Sixteen (64%) and 13 (52%) showed abnormal cVEMPs and caloric responses, respectively, on the affected side. Among the 23 patients who underwent oVEMPs, 10 (43%) showed abnormal oVEMPs on the affected side. Of these 23 patients, 6 (26%) were classified as C type, 4 (17%) as CS type, 1 (4%) as CL type, 1 (4%) as CSU type, 2 (9%) as CSL type, 1 (4%) as CUL type, 8 (35%) as CSUL type. ConclusionThe vestibular end organs close to the cochlea tended to be preferentially affected. SignificanceIt is likely that vestibular dysfunction extends from organs close to the cochlea to those further from the cochlea.

Clinical uses of cervical vestibular-evoked myogenic potential testing in pediatric patients.

To demonstrate the feasibility and clinical significance of cervical vestibular-evoked myogenic potential (cVEMP) test in pediatric patients.Retrospective review study was conducted in a pediatric tertiary care facility. A total of 278 patients were identified with adequate data, including medical notes, results of cVEMP, and imaging studies.Among the total of 278 pediatric patients, only 3 children were not able to finish the cVEMP test successfully. In about 90% of the cases, the cVEMP test was requested to investigate a patient’s hearing loss and/or vestibular complaints. Over 90% of the cVEMP tests were ordered by specialists such as pediatric otolaryngologists or otologists. Obtained cVEMP results provided useful information in clinical diagnosis and management in all cases.It is feasible to conduct cVEMP testing in children, including infants, and cVEMP testing can provide valuable information in the diagnosis and management of hearing loss and vestibular impairment. This simple and noninvasive test should be embraced by pediatric professionals.

Role of ocular VEMP test in assessing the occurrence of vertigo in otosclerosis patients

ObjectiveThis study adopted an inner ear test battery comprising audiometry, caloric test, ocular vestibular-evoked myogenic potential (oVEMP) test and cervical VEMP (cVEMP) test to find the factors related to the occurrence of vertigo in patients with otosclerosis. MethodsFifty otosclerosis patients comprising 27 patients with vertigo (Group A) and 23 patients without vertigo/dizziness (Group B) were enrolled. Each patient underwent otoscopy, image study, audiometry, caloric test, and oVEMP and cVEMP tests via bone vibration stimuli. ResultsThe sequence of inner ear deficits in Group A was in the order from oVEMP test (84%), cVEMP test (51%), caloric test (38%) and mean bone-conducted (BC) hearing threshold (14%), exhibiting a significantly declining trend (p<0.001). The rate of inner ear dysfunction in Group B also declined significantly but in a different order – cVEMP test (55%), oVEMP test (52%), mean BC hearing threshold (33%), and caloric test (18%). Comparison between the two groups revealed a significant difference in the oVEMP test results (p<0.01), but not in the results of the BC hearing threshold, caloric test or cVEMP test (p>0.05). Further, no significant differences existed between the BC hearing threshold and vestibular function test results. ConclusionOtosclerosis patients with vertigo have more frequent abnormalities of oVEMPs to impulsive stimulation than do those without, consistent with more frequent abnormalities of the utricle. Abnormalities of oVEMPs and cVEMPs are more frequent than for caloric testing and BC hearing thresholds. SignificanceThe relative frequency of abnormalities may reflect the degree of pathological involvement of the utricle, saccule, semicircular canals and cochlea in otosclerosis patients with vertigo.

The influence of caffeine on calorics and cervical vestibular evoked myogenic potentials (cVEMPs).

Prior to undergoing vestibular function testing, it is not uncommon for clinicians to request that patients abstain from caffeine 24 hr prior to the administration of the tests. However, there is little evidence that caffeine affects vestibular function. To evaluate whether the results from two tests commonly used in a clinical setting to assess vestibular function (i.e., calorics and the cervical vestibular evoked myogenic potential [cVEMP]) are affected by caffeine. Subjects were tested with and without consuming a moderate amount of caffeine prior to undergoing calorics and cVEMPs. Thirty young healthy controls (mean = 23.28 yr; females = 21). Subjects were excluded if they reported any history of vestibular/balance impairment. The Variotherm Plus Caloric Irrigator was used to administer the water, while the I-Portal VNG software was used to collect and analyze subjects' eye movements. The TECA Evoked Potential System was used for the cVEMP stimulus presentation as well as for the data collection. During cVEMP collection, subjects were asked to monitor their sternocleidomastoid muscle contraction with a Delsys EMG monitor. IBM SPSS Statistics 20 was used to statistically analyze the results via paired t-tests. Analysis of the data revealed that ingestion of caffeine did not significantly influence the results of either test of vestibular function. The results revealed that a moderate amount of caffeine does not have a clinically significant effect on the results from caloric and cVEMP tests in young healthy adults. Future research is necessary to determine whether similar results would be obtained from individuals with a vestibular impairment, as well as older adults.

Rotatory and Collic Vestibular Evoked Myogenic Potential Testing in Normal-Hearing and Hearing-Impaired Children

Vertigo and imbalance are often underestimated in the pediatric population, due to limited communication abilities, atypical symptoms, and relatively quick adaptation and compensation in children. Moreover, examination and interpretation of vestibular tests are very challenging, because of difficulties with cooperation and maintenance of alertness, and because of the sometimes nauseatic reactions. Therefore, it is of great importance for each vestibular laboratory to implement a child-friendly test protocol with age-appropriate normative data. Because of the often masked appearance of vestibular problems in young children, the vestibular organ should be routinely examined in high-risk pediatric groups, such as children with a hearing impairment. Purposes of the present study were (1) to determine age-appropriate normative data for two child-friendly vestibular laboratory techniques (rotatory and collic vestibular evoked myogenic potential [cVEMP] test) in a group of children without auditory or vestibular complaints, and (2) to examine vestibular function in a group of children presenting with bilateral hearing impairment. Forty-eight typically developing children (mean age 8 years 0 months; range: 4 years 1 month to 12 years 11 months) without any auditory or vestibular complaints as well as 39 children (mean age 7 years 8 months; range: 3 years 8 months to 12 years 10 months) with a bilateral sensorineural hearing loss were included in this study. All children underwent three sinusoidal rotations (0.01, 0.05, and 0.1 Hz at 50 degrees/s) and bilateral cVEMP testing. No significant age differences were found for the rotatory test, whereas a significant increase of N1 latency and a significant threshold decrease was noticeable for the cVEMP, resulting in age-appropriate normative data. Hearing-impaired children demonstrated significantly lower gain values at the 0.01 Hz rotation and a larger percentage of absent cVEMP responses compared with normal-hearing children. Seventy-four percent of hearing-impaired children showed some type of vestibular abnormality when examined with a combination of rotatory and cVEMP testing, in contrast to an abnormality rate of 60% with cVEMP and a rate of 49% with rotatory testing alone. The observed pediatric age correlations underscore the necessity of age-appropriate normative data to guarantee accurate interpretation of test results. The high percentages of abnormal vestibular test results in hearing-impaired children emphasize the importance of vestibular assessment in these children because the integrity of the vestibular system is a critical factor for motor and psychological development.

Mapping affected territory of anterior/posterior inferior cerebellar artery infarction using a vestibular test battery

Conclusion: Although the affected territory in the posterior/anterior inferior cerebellar artery (PICA/AICA) infarction could not be meticulously demonstrated by magnetic resonance imaging (MRI), it could be picked up by the results of a vestibular test battery comprising caloric, ocular vestibular evoked myogenic potential (oVEMP), and cervical VEMP (cVEMP) tests. Objectives: This study applied audiometry and caloric, oVEMP, and cVEMP tests to map affected territory in patients with PICA/AICA infarction. Methods: Fourteen patients, including 11 with PICA infarction and 3 with AICA infarction, were enrolled in this study during the last 8 years. Each patient underwent audiometry, caloric test, oVEMP test, and cVEMP test. Results: In the PICA group, 8 (36%) of 22 ears had a mean hearing level >25 dB. All six ears (100%) in the AICA group had abnormal hearing, and thus both groups revealed a significant difference. Conversely, significant differences were not observed in the vestibular test battery between the PICA and AICA groups. MRI demonstrated infarction at the brainstem for six patients, while one patient also had cerebellar involvement, indicated by loss of visual suppression on caloric nystagmus. Six patients showed infarction at the cerebellum, and four of them had brainstem affliction based on abnormal oVEMP/cVEMP test results.

Registering grades of sudden deafness to predict the hearing outcome via an inner-ear test battery

Objectives: An inner ear test battery comprising audiometry and ocular vestibular-evoked myogenic potential (oVEMP), cervical VEMP (cVEMP), and caloric tests was applied to patients with sudden deafness to map their lesions and predict hearing outcome. Design: Retrospective study. Study sample: Seventy-five patients with unilateral sudden deafness underwent an inner-ear test battery. Registering the grades of sudden deafness was based on the number of abnormal test results in the inner ear test battery. Results: After treatment for three consecutive months, mean hearing gain declined significantly from Grade I (one abnormal test) to Grade IV (four abnormal tests). Significant relations existed between hearing outcome and oVEMP test results (p < 0.05), caloric test results (p < 0.05), but not cVEMP test results and pre-treatment mean hearing level. Combined caloric and oVEMP test results demonstrated a stronger predictor with a c statistic of 0.722 than either test alone, indicating that this regression model fits the whole set of observations well and is effective in predicting the hearing outcome. Conclusion: Abnormal caloric and oVEMP test results in sudden deafness patients may indicate poor prognosis for hearing improvement, whereas hearing recovery can be anticipated when both tests reveal normal responses.

Feasibility of simultaneous recording of cervical and ocular vestibular-evoked myogenic potentials via galvanic vestibular stimulation

Conclusion: Simultaneous galvanic vestibular stimulation (GVS)-cervical vestibular-evoked myogenic potential (cVEMP) and GVS-ocular (oVEMP) tests yielded similar information to that obtained in individual tests. Objective: This study compared the characteristic parameters of cVEMPs and oVEMPs via GVS between individual and simultaneous recording patterns in healthy and elderly subjects. Consequently, the effectiveness of simultaneous GVS-cVEMP and GVS-oVEMP tests was assessed. Methods: A total of 24 healthy and 16 elderly subjects were enrolled in this study. All participants underwent individual cVEMP, individual oVEMP, and simultaneous cVEMP and oVEMP testing via GVS mode in a random order. The response rates and characteristic parameters of cVEMPs and oVEMPs between individual and simultaneous tests, including latencies, intervals, and amplitudes, were measured. Results: The VEMP parameters, including latencies, intervals, and amplitudes, all demonstrated no significant differences between individual and simultaneous tests (p > 0.05, paired t test), either in healthy or elderly subjects. Pearson's correlation analyses also revealed significant positive correlations in all parameters between these two tests (p < 0.05).

Inner ear deficits after chronic otitis media

Investigation of the causes of vestibular symptoms in patients with chronic otitis media (COM) faces frustration, mainly because the bithermal caloric test using tap water is generally contraindicated in perforated ears. This study utilized audiometry, ocular vestibular-evoked myogenic potential (oVEMP) test, and cervical VEMP (cVEMP) test to evaluate inner ear deficits after COM. A total of 85 COM patients (117 ears) underwent otoscopy, image study, audiometry, oVEMP test, and cVEMP test. Mean bone-conducted (BC) hearing threshold ≤25 dB was observed in 74 ears, 26-40 dB in 30 ears, and >40 dB in 13 ears. Restated, abnormal BC hearing threshold was identified in 43 ears (37 %). Percentages of abnormal cVEMP test, oVEMP test, and BC hearing threshold in 117 COM ears were 65, 62, and 37 %, respectively, exhibiting a significantly declining sequence in inner ear function. Furthermore, cVEMP/oVEMP test results were significantly correlated with BC hearing threshold, whereas no correlation existed between the cVEMP and oVEMP test results. In conclusion, the sequence of inner ear deficits after COM runs from the saccule/utricle to the cochlea and semicircular canals. Restated, in addition to BC hearing test, the cVEMP/oVEMP test may serve as a supplementary tool for early detection of inner ear involvement in COM patients.

Differentiating cerebellopontine angle meningioma from schwannoma using caloric testing and vestibular-evoked myogenic potentials

ObjectiveThis study utilized audiometry, and caloric, ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests to differentiate between cerebellopontine angle (CPA) meningioma and schwannoma. Patients and methodsEleven CPA meningioma patients with mean tumor size 2.8±1.4cm and another 11 CPA schwannoma patients with mean tumor size 2.7±1.0cm were enrolled in this study. All patients underwent a battery of audiovestibular function tests. ResultsThe two groups did not differ significantly in terms of clinical manifestation. The abnormal percentage of caloric test in the meningioma group was 36%, compared to 91% in the schwannoma group, and thus both groups differed significantly. However, such difference was not observed between the two groups regardless of mean hearing level, oVEMP test and cVEMP test. ConclusionCombined caloric with oVEMP test results may help differentiate a CPA tumor. Correlation between the caloric and oVEMP test results in a CPA tumor indicates a schwannoma nature, while dissociation between the caloric and oVEMP test results depicts a meningioma character.

Secondary endolymphatic hydrops after sudden deafness

Conclusion: Patients with sudden deafness who had abnormal ocular vestibular-evoked myogenic potential (oVEMP)/cervical VEMP (cVEMP) responses but retained caloric function may subsequently develop secondary hydrops with a mean interval of 8 years. Objective: This study applied the inner ear test battery in patients who had sudden deafness previously to elucidate how secondary endolymphatic hydrops occurs years after sudden deafness. Methods: Twenty patients who had experienced recent vertiginous attacks several years after sudden deafness (group A) and 20 patients without rotational vertiginous episode for at least 5 years following sudden deafness (group B) were enrolled. All patients underwent an inner ear test battery comprising audiometry, caloric test, and oVEMP and cVEMP tests. Results: The mean interval from initial sudden deafness to vertiginous attack in group A was 8 years, with a mean hearing level of 66 ± 20 dB, which did not significantly differ from 61 ± 20 dB in group B. For the vestibular test results, the percentages of abnormal cVEMP, oVEMP, and caloric tests in group A were 65%, 70%, and 25%, respectively. Compared to the respective 70%, 60%, and 75% abnormalities in group B, only the caloric test differed significantly.

Correlations Between Foam Posturography and Vestibular-Evoked Myogenic Potential Tests in Ménière’s Disease

This study adopted foam posturography coupled with inner ear test battery including audiometry, and cervical Vestibular-Evoked Myogenic Potential (cVEMP), ocular Vestibular-Evoked Myogenic Potential (oVEMP) and Caloric tests in patients with Ménière's disease to investigate the relations between them. Fifty patients with unilateral definite Ménière's disease were enrolled. All patients underwent Audiometry, and Caloric, oVEMP, and cVEMP tests. In addition, posturography was also performed under 4 conditions: A (firm surface, eyes open), B (firm surface, eyes closed), C (foam pad, eyes open), and D (foam pad, eyes closed). Romberg quotient (RQ) was measured as the value from eyes closed divided by that from eyes open. No correlation existed between Ménière stage and RQ measured with foam pad. Mean RQ of the sway area on foam pad in Ménière's patients with abnormal oVEMPs (1.75 ± 0.95) was significantly larger than 1.20 ± 0.70 in those with normal oVEMPs. However, neither cVEMP nor Caloric test results were associated with RQ on foam pad (p > 0.05). Further, the area under the receiver operating characteristic curve of the RQ of sway area on foam pad in discrimination between normal and abnormal oVEMP test was 0.65 (95% CI, 0.51 to 0.79; p < 0.05), implying that RQ of the sway area on foam pad may serve as a significant predictor for abnormal oVEMP test. By removing or reducing both visual and somatosensory inputs from foam posturography, the remaining vestibular cue, represented as RQ of sway area on foam pad, may reflect utricular function.

Vestibular evoked myogenic potentials and habituation to seasickness

ObjectiveSeasickness may impose severe limitations on the performance of ships’ crew. Cervical vestibular evoked myogenic potentials (cVEMP) assess the function of the saccule, the organ responsible for monitoring vertical linear acceleration, which has been found to be the most provocative motion stimulus in the evolution of motion sickness. We used the cVEMP test in a prospective evaluation of susceptibility and habituation to seasickness. MethodsForty-six naval recruits underwent the cVEMP test before exposure to sea conditions. After 6months’ sailing experience, participants completed a questionnaire evaluating their initial and current seasickness severity. Based on their most recent experience, subjects were divided into three groups: non-vomiting non-habituating (NV-NH), vomiting (V), and non-vomiting habituating (NV-H). ResultsStatistically significant lower thresholds for cVEMP were found in subjects who habituated to sea conditions (NV-H), compared with those remaining severely susceptible (V) (77.0dB HL vs. 84.9dB HL; p<0.01). ConclusionsThe ability to produce the cVEMP at lower thresholds represents a broader dynamic range, in which the reflex can respond to a wider array of stimuli amplitudes. SignificanceThe present study demonstrates the potential of the cVEMP test for predicting future habituation to seasickness.

A Proposed Method to Comprehensively Define Outcomes in Acoustic Tumor Patients Undergoing CyberKnife Management

Background: Vestibular assessment in patients with acoustic tumor (so-called vestibular schwannoma, VS) via ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests are not often discussed in the neurosurgical literature. Objectives: This study conducted physiological and morphological assessments for VS patients before and after CyberKnife radiosurgery. Methods: Twenty patients with unilateral VS underwent a battery of tests comprising facial nerve function test, audiometry, and caloric, oVEMP and cVEMP tests before and 2 years after CyberKnife treatment at a mean dosage of 18 Gy in 3 fractions. Results: The abnormal percentages of caloric, oVEMP and cVEMP tests did not significantly differ before and after Cyberknife treatment, indicating that preservation of the superior and inferior vestibular nerves can be achieved after radiosurgery. Median tumor volumes, 1.49 cm³ before treatment versus 0.97 cm³ at 2 years after treatment, differed significantly. Conclusions: The use of oVEMP and cVEMP tests in VS patients before stereotactic radiosurgery may help to evaluate the tumor origin from the superior or inferior vestibular nerve. It takes a short time and costs less, and it would be practical to make this a routine examination in VS patients having stereotactic radiosurgery.

Comparison of head elevation versus rotation methods for eliciting cervical vestibular-evoked myogenic potentials via bone-conducted vibration

Objectives: This study investigated the feasibility of the cervical vestibular-evoked myogenic potential (cVEMP) test using bone-conducted vibration (BCV) tapping. Design: Prospective study. Study sample: Initially, 20 healthy volunteers aged 23–38 years underwent cVEMP tests in supine position using head elevation method by BCV tapping at the Fz and inion. On another day, the same subjects underwent cVEMP tests in seated position with head rotation method by BCV tapping at the Fz and inion. Another 20 healthy subjects aged 41–60 years undergoing cVEMP tests by BCV tapping at the inion were also included for comparison. Results: Tapping at the inion (100%) had significantly higher response rate of cVEMPs than tapping at Fz (65–70%), regardless of whether the head was elevated or rotated. Except for mean latencies of p13 and n23, the mean p13-n23 amplitude, corrected amplitude, and asymmetry ratio did not differ significantly between the elevation and rotation methods when cVEMPs were elicited by inion tapping; both methods showed excellent test-retest reliability. Conclusions: The BCV at the inion is the optimal method for eliciting BCV cVEMPs. These responses can be recorded using either the seated/head rotation method or supine/head elevation method.

Influence of thresholds on amplitudes in vestibular evoked myogenic potentials

To investigate the relationship between the threshold and the interaural amplitude difference ratio (IADR) in cervical vestibular evoked myogenic potential (cVEMP) testing and pursuit the clinical significance of the parameters. cVEMP responses were recorded while the SCM contraction was controlled using a pressure cuff. The intensities of the sound stimulation decreased from 95 dB n HL by 5 dB, until no responses were evoked. Thresholds, interaural threshold difference (ITD), amplitudes, and interaural amplitude difference ratio at the stimulation of 95 dB n HL were calculated and the relationship between them was examined. All subjects showed cVEMP responses bilaterally. Thresholds measured were overall 76 dB n HL and most (92%) ears showed the ITD of 0 or 5 dB. The amplitudes of cVEMP responses showed a positive correlation with the sound intensities, and more specifically with the sound intensity above each threshold value. There was no significant difference in IADR values by the ITD. Based on our study, the ITD is less than 10 dB in most normal subjects and estimation of threshold should be added to cVEMP testing for probing vestibular asymmetry. Getting a threshold might be helpful in determining whether the abnormal interaural amplitude difference ratio is related to the abnormal ITD.