Normal Vestibular Evoked Myogenic Potential Research Articles

Comparison of the Vestibular Evoked Myogenic Potential and the Blink Reflex in Cerebellar and Brainstem Infarction Patients

Objective: This study investigated whether the blink reflex could be substituted for the vestibular evoked myogenic potential (VEMP), which has some limitations for use in stroke patients.Methods: Thirty-four patients with cerebellar or brainstem ischemic stroke underwent VEMP and blink reflex testing. We compared the P13 latency of VEMP and the R1, R2, R2’ latency of the blink reflex in stroke patients. Statistical analysis was conducted using the Fisher exact test and independent t-test, with a p-value < 0.05 indicating statistical significance.Results: In 29 stroke patients, excluding those with bilateral lesions, the VEMP and the blink test did not show a statistically significant relationship (p = 0.2701). In all 34 stroke patients participating in the study, including those with bilateral lesions, R2’ mean showed a statistically significant difference (p = 0.0081) according to the presence of normal or abnormal VEMP. Conclusion: R2’ of the blink reflex passes through more neural pathways and polysynaptic pathways than R1 and R2; therefore, it showed a more prominent difference between the normal and abnormal VEMP groups.

Isolated Otolith Dysfunction in Persistent Postural-Perceptual Dizziness.

The aims of this study were to investigate otolith dysfunction, especially isolated otolith dysfunction (with preserved semicircular canal function) in persistent postural-perceptual dizziness (PPPD) patients. Twenty-one patients who had been diagnosed with PPPD were enrolled in this study. The subjects filled out questionnaires [the Dizziness Handicap Inventory (DHI) and the Niigata PPPD Questionnaire (NPQ)] and underwent vestibular evoked myogenic potential (VEMP) tests, video head-impulse tests (vHIT), and stabilometry. Among the 21 subjects with PPPD, 9 showed isolated otolith dysfunction, 4 exhibited both otolith dysfunction and semicircular canal dysfunction, and 2 demonstrated isolated semicircular canal dysfunction. Six subjects exhibited normal VEMP and vHIT results. Concerning the subjects' questionnaire scores and stabilometric parameters, there were no significant differences among subgroups when the subjects were classified according to their VEMP and vHIT results while stabilometric parameters obtained in PPPD subjects were significantly increased than published data of healthy subjects. As precipitating conditions for PPPD, vestibular neuritis was the most frequent and the second most was idiopathic otolithic vertigo. In conclusion, the majority of PPPD patients had otolith dysfunction, and most of them showed isolated otolith dysfunction. Idiopathic otolithic vertigo can be a precipitating factor of PPPD. While otolith dysfunction may be associated with initiation of PPPD symptoms, PPPD symptoms are also considered to be associated with other dysfunctions of the sensory processing system.

Usefulness of vestibular evoked myogenic potentials in diagnosis of peripheral vestibular disorders

<p><strong>Background: </strong>Vestibular evoked myogenic potentials (VEMP) are electromyographic responses to high-intensity acoustic stimuli to test vestibular system, otolith function and integrity of inferior vestibular nerve. These are easy to perform and non-invasive. In this study, we aimed at clinical application of VEMP to evaluate common peripheral vestibular disorders.<strong></strong></p><p><strong>Methods: </strong>Prospective observational study carried in ENT department during January 2015-November 2016 over 40 patients in age group between 30-70 years with history of vertigo who underwent regular neuro-otological examination and VEMP.</p><p><strong>Results: </strong>Of these, 25 diagnosed with BPPV, 11 with Meniere’s disease, and four with vestibular neuritis. Eight patients showed delayed VEMP responses. 28 (70%) patients had normal VEMP, 12 (30%) had abnormal VEMP responses. Out of 25 patients suffering from benign paroxysmal positional vertigo (BPPV) posterior semi-circular canal was involved in 20 (80%) patients and lateral semi-circular canal in 5 (20%) patients.<strong> </strong>Abnormal VEMP was found in 5 (20%) patients involving posterior semi-circular canal and in 1 (20%) patient involving lateral semi-circular canal. In patients with Meniere’s disease stage I, Meniere’s disease was observed in 7 (63.6%), stage II in 2 (18.1%), and stage IV disease in 1 (9.09%) patient. In these patients, abnormal VEMP was found in 3 (42.8%) of 7 stage I, 1 (50%) of 2 stage II and 1 (100%) of stage IV patients.<strong> </strong>One (20%) patient had abnormal VEMP responses during study.</p><p><strong>Conclusions: </strong>VEMP are short-latency EMG that evaluates saccule and inferior vestibular nerve in peripheral vestibular nervous system. VEMP should be considered as complementary test along with conventional vestibular function tests in patients with peripheral vertigo.<strong></strong></p>

Prognostic value of vestibular evoked myogenic potential and distortion product otoacoustic emission tests in patients with a diagnosis of sudden hearing loss: A preliminary report

Objectives: This study aims to investigate whether vestibular evoked myogenic potentials (VEMPs) and distortion product otoacoustic emissions (DPOAEs) have prognostic values in the follow-up of patients diagnosed with idiopathic sudden sensorineural hearing loss (ISSNHL) with audiological tests. Patients and Methods: Between June 2013 and January 2014, a total of 27 patients (11 males, 16 females; mean age: 44.9±13.8 years; range, 18 to 60 years) diagnosed with ISSNHL at their first admissions and underwent VEMP and DPOAE tests were included. As the treatment protocol, steroid treatment combined with hyperbaric oxygen therapy was initiated in all patients. At the second month of the treatment, all patients underwent VEMP and DPOAE tests once again. Hearing recovery was evaluated based on the hearing improvement, compared to the unaffected contralateral ear. Results: The median recovery rate was statistically significantly higher in the patients with normal pre-treatment VEMP test results than those with abnormal VEMP test results (p=0.023). The median recovery rate was statistically significantly higher in the patients with normal post-treatment VEMP test results compared to those with abnormal post-treatment VEMP test results (p=0.031). The median recovery rate was also statistically significantly higher in the post-treatment DPOAE test positivity than the post-treatment DPOAE test negativity (p<0.001). Conclusion: Our study results suggest that, in the follow-up of the prognosis of ISSNHL disease, VEMP test may have a prognostic value, while DPOAE test is an important parameter which can be used in the monitorization of the disease.

Relationship Between Galvanic Vestibular-evoked Myogenic Potentials and the Prognosis of Unilateral Severe to Profound Idiopathic Sudden Sensorineural Hearing Loss With Vertigo.

Idiopathic sudden sensorineural hearing loss (ISSNHL) may not only impair cochlear function but also damage vestibular structures, including the saccule, utricle, semicircular canals, and vestibular afferents. Poor recovery often occurs in patient with serious ISSNHL and accompanying vertigo. To define the severity of the disease and to predict prognosis, galvanic vestibular-evoked myogenic potentials (VEMPs) are added to the inner ear test battery. Retrospective case review. Tertiary referral center. Thirty patients with unilateral severe to profound ISSNHL and accompanying vertigo were enrolled in this retrospective study. Diagnostic. All subjects underwent pure tone audiometry, cervical and ocular VEMPs, and caloric tests before the initiation of treatment. The treatment outcome, rates of abnormal responses in the tests, and the characteristic parameters of VEMPs such as latencies and amplitudes, were analyzed. In affected ears, the rates of abnormal acoustic cVEMPs, vibratory oVEMPs, galvanic cVEMPs, and galvanic oVEMPs were 60, 47, 37, and 20%, respectively. The improvement in the hearing of the affected ear was specified as good recovery or poor recovery. The normal galvanic VEMP group had a significant higher rate of good recovery than abnormal galvanic VEMP group (87% versus 27%; p = 0.003). Patients with unilateral severe to profound ISSNHL and accompanying vertigo who have normal galvanic VEMPs have a higher likelihood of hearing recovery than those who have abnormal galvanic VEMPs.

Evaluation of Patients with Delayed Endolymphatic Hydrops by Videonystagmography, Vestibular-Evoked Myogenic Potentials, and Electrocochleography

Introduction: The categorization of delayed endolymphatic hydrops (DEH) based on the ear which produces vertigo may sometimes cause misdiagnosis. Objectives: The aim of this study was investigating the vestibular-evoked myogenic potentials (VEMPs), electrocochleography (ECoG), and videonystagmography (VNG) in cases with DEH to determine the ear that originates symptoms. Methods: In this cross-sectional study, 34 patients – 20 males and 14 females – with profound unilateral sensorineural deafness and vertigo attacks were recruited and evaluated by the ECoG, VNG, and VEMPs tests. Results: The average age was around 43; the summating potential/action potential was abnormal in 29.4% of patients in their normal auditive ear. In 32.4, 17.6, and 50% of cases with a deaf ear, absent, normal, and abnormal VEMPs results were sequentially observed, respectively. In normal-hearing ears, absent, normal, and abnormal VEMPs were observed in 23.5, 50, and 26.5%, respectively. In the normal-hearing ear, the distribution of abnormal VEMPs was 26.5%, and in the deaf ear, this parameter was abnormal in 50% of the opposite ear (p value = 0.00021). In the VNG test, among patients with a normal-hearing ear, results in 27 and 7 patients were sequentially normal and hypofunction. Conclusion and Significance: The probability of a hypofunction VNG test in a normal-hearing ear might be greater when the VEMPs results of the contralateral deaf ear are normal. In patients with a normal-hearing ear, the distribution of abnormal VEMPs in the contralateral deaf ear is greater, although the intact side may also manifest abnormality in VEMPs tests. The initial evaluation should begin in a deaf ear as well as for the normal-hearing ear ere utilizing ablation surgery.

Quantitative Vestibular Function Testing in the Pediatric Population.

Quantitative tests of vestibular function include the caloric test, cervical and ocular vestibular evoked myogenic potential (VEMP), rotary chair, and head impulse test, either at the bedside or utilizing video head impulse test (vHIT). The purpose of this article is to provide an overview of how to perform these tests in children, including which tests are recommended based on the child's age and any modifications or considerations that can be made. A variety of clinical measures have been recommended as screening measures for vestibular loss, which will be reviewed. Symptom questionnaires designed to assess the functional impact of dizziness and vestibular loss in children will also be discussed. If a child complains of dizziness or if vestibular loss is suspected (either by case history or positive screening measure), vestibular function testing is warranted. For vestibular function testing, children aged 0 to 2 years typically receive rotary chair, cervical VEMP, and vHIT if a remote system is available. For children aged 3 to 7 years, vHIT, cervical VEMP, and ocular VEMP are completed, and for children aged 8+ years, vHIT, caloric testing if vHIT is normal, and cervical and ocular VEMP are completed. For all children, modifications to testing can be made, as needed.

Bone-conducted Vestibular-evoked Myogenic Potentials Before and After Stapes Surgery.

To identify whether stapes surgery causes otolith dysfunction using bone-conducted vestibular-evoked myogenic potentials (VEMPs). Prospective study. Hyogo College of Medicine Hospital. Twenty primary ears (19 otosclerosis, 1 congenital stapes fixation) in 17 patients (2 men, 15 women; mean age 51 yr, range 20-68 yr) who had normal cervical VEMP (cVEMP) and ocular VEMP (oVEMP) results with bone-conducted stimulation were included. Stapes surgery. Both VEMP tests with bone-conducted stimulation were performed before and after stapes surgery. The normalized p13-n23 amplitude of cVEMPs and the nI-pI amplitude of oVEMPs were measured within 3 months after stapes surgery. Then, the asymmetry ratio (AR) was calculated to examine the effect of surgery on otolith function. Seven patients complained of temporary dizziness postoperatively, but their symptoms disappeared within approximately a week. Deterioration of VEMPs of the operated ear was not seen in any ears. Significantly greater amplitude compared with the opposite ear was found for cVEMP in one ear and oVEMP in two ears after the surgery. Their VEMP results recovered to the normal range at 6 months postoperatively. These findings suggest that stapes surgery causes no or undetectably small otolith dysfunction from the perspective of VEMP evaluation.

Otolith function assessment in patients with systemic sclerosis

IntroductionAudiovestibular dysfunction has been reported in connective tissue disease patients. Evaluation of the otolith organ function as a part of the vestibular system of the inner ear in systemic sclerosis (SSc) patients is still greatly uncovered in the literature. Aim of workTo assess otolith function in SSc patients and to correlate the findings with the clinical characteristics and disease severity. Patients and methodsThirty SSc patients and 30 matched controls were included in this work. All patients were subjected to full history taking, clinical examination, assessment disease severity by modified Rodnan skin score (mRss), relevant laboratory and radiological tests. All patients had otolith function assessment using Vestibular Evoked Myogenic Potentials (VEMP) and auditory assessment done using pure tone audiometry (PTA), speech audiometry and tympanometry. ResultsAuditory assessment revealed bilateral sensorineural hearing loss (SNHL) in 11 (36.6%) patients an abnormal VEMP response was found in 24 (80%). The mean latencies of P13 and N23 were significantly prolonged than in the controls (p<0.001). Sine scleroderma subtype was significantly more frequent in SSc patients with normal VEMP (p=0.04). Skin thickening was significantly more frequent in those with abnormal VEMP (p=0.04) and the mRss score was also significantly increased (p=0.007). Those with hearing loss were significantly older in age (p=0.03) and had a significantly longer disease duration (p=0.01) and had a significantly increased frequency of digital pitting (p=0.02) and ulcers (p=0.03) compared to those with normal hearing. ConclusionOur results showed an evidence of inner ear involvement in SSc causing audiovestibular abnormalities.

Prognostic significance of vestibulospinal abnormalities in patients with vestibular migraine.

We evaluated vestibular function test results in vestibular migraine (VM) patients, including caloric, vestibular evoked myogenic potential (VEMP), and dynamic posturography measurements and assessed their relationship with treatment responses. Retrospective case series review. Tertiary referral center. We investigated a cohort of 80 VM patients who had suffered recurrent vertigo attacks for more than 6 months. A combination of lifestyle modifications and prophylactic medications were used to treat these subjects. The patients were asked to score the treatment success by ranking symptom score from 0% to 100% for the improvement in overall severity of headache and vertigo. Patients were then classified as complete remission, symptomatic improvement 50% or more, or less than 50% improvement after 6 months of treatment. The periods needed for symptomatic improvement in the 50% or more patient group were recorded, and the responsiveness to medications and the vestibular test result metrics were analyzed to identify clinical outcome predictors. A symptomatic improvement of 50% or more in vertigo and headache was observed in 71% and 75% of the study subjects across mean periods of 2.3 and 2.2 months, respectively. Improvements in vertigo and headache did not coincide in all. Abnormal caloric, VEMP, and vestibular ratio measurements were found in 25%, 29%, and 58%, respectively. Abnormal vestibular ratios on posturography showed a significant correlation with a poor treatment response of vertigo, and a normal VEMP was significantly related to complete remission from headache, although abnormal caloric results showed no significant correlation with treatment responses. A poor response of vertigo symptoms was observed in 6% of patients with a normal vestibular ratio and 48% of patients with abnormal vestibular ratio. Complete remission from headache was observed in 61% of patients with a normal VEMP and 30% in patients with an abnormal VEMP. More than 70% of the patients with VM experienced improvements in both headache and vertigo through a combination of lifestyle changes and prophylactic medications. Abnormal vestibular ratios on posturography and abnormal VEMP responses were frequent findings in VM patients with recurrent attacks for more than 6 months and were indicators of a poor prognosis. The pathophysiology of VM appears to be closely related to vestibular abnormalities, especially in vestibulospinal pathways. Further study with a large population is needed to establish the relationship exactly. 2b Individual retrospective cohort study.

Vestibular Evoked Myogenic Potential Produced by Bone-Conducted Stimuli: A Study on its Basics and Clinical Applications in Patients with Conductive andSensorineural Hearing Loss and a Group with Vestibular Schawannoma.

Vestibular evoked myogenic potential (VEMP) has recently been broadly studied in vestibular disorders. As it is evoked by loud sound stimulation, even mild conductive hearing loss may affect VEMP results. Bone-conducted (BC) stimulus is an alternative stimulation for evoking this response. This study aims to assess the characteristics of BC-VEMP in different groups of patients. We performed a cross sectional analysis on 20 healthy volunteers with normal pure-tone audiometry as a control group; and on a group of patients consisted of 20 participants with conductive hearing loss, five with bilateral sensorineural hearing loss and four with vestibular schawannoma. AC and BC-VEMP were performed in all participants. In control group the VEMP responses to both kinds of stimuli had an acceptable morphology and consisted of p13 and n23 waves. Latency value of these main components in each type of stimulus was not significantly different (P>0.05). However, the mean amplitude was larger in BC modality than AC stimulation (P=0.025). In the group with conductive hearing loss, the VEMP response was absent in fifteen (46.87%) of the 32 ears using the AC method, whereas all (100%) displayed positive elicitability of VEMP by BC method. Normal VEMP responses in both stimuli were evoked in all patients with sensorineural hearing loss. In patients with unilateral vestibular schwannomas (VS), 2 (50.00%) had neither AC-VEMP nor BC-VEMP. Auditory stimuli delivered by bone conduction can evoke VEMP response. These responses are of vestibular origin and can be used in vestibular evaluation of patients with conductive hearing loss.

Vestibular evoked myogenic potential in sudden sensorineural hearing loss

Aim and Objective: To investigate saccular damage in patients with sudden sensorineural hearing loss (SSNHL) with or without vertigo and to evaluate the saccular damage according to the hearing loss and presence or absence of vertigo. Materials and Methods: All tests done in this study were performed in the audio vestibular unit of ENT department from September 2009 to November 2010. Statistical Analysis Used: The association between the severity of hearing loss and changes in the vestibular evoked myogenic potential (VEMP) recordings were assessed using descriptive statistics. The pattern of VEMP in different diseases and also the behavior of VEMP in presence or absence of vertigo were evaluated using SPSS 15. Results: Among 27 patients there were 11 cases of idiopathic SSNHL. Out of nine unaffected ears, 88% had normal and 12% had absent VEMP. Whereas out of 13 affected ears, only 53.9% had normal VEMP. Among all the 54 ears, 17 ears had normal hearing. In this group 76.47% had normal VEMP. The group with hearing loss > 90 dB had 61.53% absent VEMP. Conclusions: In patients with unilateral SSNHL, there was a tendency for the affected ear to have absent VEMP indicating the saccular involvement. The extent of saccular damage did not correspond to the amount of hearing loss or presence or absence of vertigo.

The Role of Vestibular Function Tests in Patients with Sudden Sensorineural Hearing Loss Who Have Subclinical Vestibular Dysfunction

Background and ObjectivesZZThe evaluation of vestibular function is very important for patients with sudden sensorineural hearing loss (SNHL) as it is a well-known prognostic factor. The purpose of this study was to evaluate subclinical vestibular dysfunction (SVD) and its association with prognosis in sudden SNHL patients with and without dizziness using the vestibular function tests. Subjects and MethodZZSeventy eight patients who had been diagnosed with unilateral sudden SNHL were examined by dividing them into three groups according to their clinical findings such as vestibular function and subjective symptoms: 1) normal, 2) SVD and 3) dizziness. Vestibular dysfunction and hearing recovery rates were also assessed. ResultsZZPatients with SVD accounted for 62.5% of patients even though they did not complain subjective dizziness. The extent of vestibular dysfunction in the dizziness group was greater than that in the SVD group (p=0.05). The hearing recovery rates for normal, SVD and dizziness group were 72% (13/18), 57% (17/30) and 48% (12/25), respectively. The incidence and extent of vestibular dysfunction was greater in patients with severe hearing loss than in those with moderate to severe loss. A significant correlation was noted between hearing recovery rate and vestibular evoked myogenic potential (VEMP) testing. Normal and abnormal VEMP data were associated with good and poor recovery (p=0.001). ConclusionZZThe evaluation of vestibular function is important in sudden SNHL patients with dizziness; however, SVD also explains a significant proportion of sudden SNHL in the absence of dizziness. Notably, VEMP is useful tools for evaluating prognosis of sudden SNHL. � Korean J Otorhinolaryngol-Head Neck Surg 2013;56:700-5

Testing the vestibular evoked myogenic potential (VEMP) to identify subclinical neurological alterations in different phases of human T-lymphotropic virus type 1 infection

Background contextThe diagnosis of human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is based on clinical signs and the confirmation of HTLV-1 infection in the central nervous system. Electrophysiological tests may facilitate an earlier diagnosis of spinal cord involvement. Vestibular evoked myogenic potential (VEMP) testing evaluates the vestibulospinal tract, which is correlated with the motor tract; the target of damage by HAM/TSP. PurposeThis study examines the subclinical neurological alterations related to HTLV-1 infection in individuals with asymptomatic HTLV-1 infections, possible HAM/TSP, and confirmed HAM/TSP. Study designVestibular evoked myogenic potential testing was performed at the beginning of the study and repeated every 6 months for 18 months. Ninety volunteers were selected for the study: 30 were HTLV-1 seronegative (the control group) and 60 were HTLV-1 seropositive (of these, 18 were asymptomatic, 25 had possible HAM/TSP, and 17 had confirmed HAM/TSP). The VEMP response was classified as normal or abnormal (latency prolongation or no response). A change in the VEMP response from normal to abnormal was the event of interest. To perform a survival analysis, the subjects with normal VEMP responses at the first assessment were selected. MethodsThe results were analyzed blindly. Vestibular evoked myogenic potential was measured using short tone bursts as acoustic stimuli (1 kHz, 118 dBHL, a rise-fall of 1 millisecond, and a plateau of 2 milliseconds). The stimulation rate was 5 Hz, and the analysis time for each response was 60 milliseconds; each trial averaged 200 responses. ResultsThe mean age of the subjects in the control group was 38±11 years (median 35), and 13 (43%) were men. In the study group, the mean age was 51±12 years (median 53), and 12 (20%) were men. An analysis of the survival curve indicated that the median time for a change in VEMP response from normal to abnormal was 18 months, which is in agreement with the slow progression of HTLV-1-associated neurologic disease. The survival analysis showed that the change in VEMP response was significantly different between the asymptomatic and HAM/TSP groups (p=.02). ConclusionsVestibular evoked myogenic potential testing was useful for monitoring the development of HAM/TSP in HTLV-1-infected individuals.

Hearing outcome of recurrent sudden deafness: Ipsilateral versus contralateral types

Conclusion: Patients with recurrent sudden deafness demonstrating normal vestibular-evoked myogenic potentials (VEMPs) in the lesion ear of the second episode may indicate a good hearing outcome. Objective: This study retrospectively reviewed our experience of patients with recurrent sudden deafness during the past 20 years. Methods: Sixteen (1.4 %) of 1156 patients with sudden deafness were diagnosed as having a recurrent episode, including ipsilateral type in 7 and contralateral type in 9. All patients underwent an audiovestibular test battery and blood and MRI examinations. After 2000, nine patients underwent the VEMP test. Results: In the ipsilateral type, the mean interval between two episodes was 2 ± 2 years, which did not differ significantly from 3 ± 3 years in the contralateral type. There were no significant differences in relation to age at onset of the second episode, inter-episode interval, gender, presence of vertigo, and abnormal caloric results. However, abnormal rate of VEMP test in the contralateral type (five of five patients) was significantly higher than that in the ipsilateral type (none of four patients). At the second episode, all four patients with normal VEMPs on the lesion ear had improved hearing, while four of five patients with absent or delayed VEMPs showed unchanged hearing. Altogether, the hearing improvement rate in both types of recurrent sudden deafness was 50%.

前庭血管系反射と起立性循環調節

There is little definitive evidence of the clinical significance of the vestibular-cardiovascular reflex in humans, despite the fact that the vestibular system is known to contribute to cardiovascular control in animals. Our first finding in this paper was that about 10% of 1479 dizzy patients in our hospital met the criteria for orthostatic hypotension (OH) set by the American Autonomic Society (2011). Second, a positive rate of the criteria for the OH was significantly higher in patients with abnormal subjective visual vertical (SVV) than patients with normal SVV, however abnormality of canal function did not affect the positive rate of the OH. Third, we classified 248 dizzy patients aged<65 into three groups based on their vestibular evoked myogenic potential (VEMP) responses; absent VEMP, asymmetry VEMP and normal VEMP. In order to investigate the effect of the otolith disorder, which was estimated by the VEMP, on the orthostatic blood pressure responses, the subjects' systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate were monitored during the orthostatic test after standing up. The male patients in the absent VEMP group presented a significant drop in their DBP at 1 min. after standing up (p<0.05) without any change in SBP. In the entire group of participants, a total of 19.6% of the patients in the absent VEMP group fulfilled the criteria for orthostatic hypotension (OH), which was significantly larger than the 8.6% of patients in the normal VEMP group and the 7.2% in the asymmetry VEMP group (P<0.05). Our results suggest that vestibular disorders due to the dysfunction of otolith organs provoke OH.

Evidence for vestibular dysfunction in orthostatic hypotension

There is little definitive evidence of the clinical significance of the vestibular-cardiovascular reflex in humans, despite the fact that the vestibular system is known to contribute to cardiovascular control in animals. The present study involved 248 dizzy patients (127 male patients and 121 female patients) aged 65years and younger. We classified all participants into three groups based on their vestibular evoked myogenic potential (VEMP) responses; absent VEMP, asymmetry VEMP and normal VEMP. To investigate the effect of the otolith disorder, which was estimated by the VEMP, on the orthostatic blood pressure responses, the subjects' systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate were monitored during the orthostatic test after they actively stood up. The male patients in the absent VEMP group had a significant drop in their DBP at 1min after active standing up (P<0.05) without any change in their SBP. Conversely, male patients in the asymmetry VEMP and normal VEMP groups showed a significant increase in the SBP at 1min after active standing up (P<0.05). Female patients in the absent VEMP group did not show any significant drop in their blood pressure after standing up (P>0.05). In the entire group of participants, a total of 19.6% of the patients in the absent VEMP group fulfilled the criteria for orthostatic hypotension (OH), which was significantly > the 8.6% of patients in the normal VEMP group and the 7.2% in the asymmetry VEMP group (P<0.05). Our results suggest that vestibular disorders due to the dysfunction of otolith organs provoke OH.

Brainstem representation of vestibular evoked myogenic potentials

Vestibular evoked myogenic potentials (VEMPs) are caused by a short-latency reflex recorded from averaged electromyography from the sternocleidomastoid muscle evoked by intense auditory clicks. Besides peripheral vestibulopathy, abnormal VEMPs can be caused by lesions of the brainstem. The aim of this study was to analyze the topology of ischemic brain lesions generating pathological VEMPs. Twenty-nine patients with brainstem infarcts were prospectively studied using VEMPs and MR imaging to evaluate the brainstem representation of the VEMP reflex. Individual brainstem lesions were projected to a standard MR-dataset for normalization. Probabilistic lesion maps were calculated. A digital brainstem atlas was fitted to the lesion maps. Twelve patients showed unilaterally abnormal VEMPs, 10 patients had normal VEMPs. Seven patients with bilaterally absent VEMPs were not analyzed. Most lesions were located in the lateral medulla oblongata involving the spinal accessory nerve. Most lesions in the pons were associated to anterolateral parts of pyramidal tract fibers. In a few cases, lesions were located in the tegmental area of the pons, including the vestibular nuclei. Abnormal VEMPs may be produced not only by peripheral vestibulopathy but also by brainstem lesions. VEMPs may be influenced by effects caused by lesions located above the level of the vestibular nuclei. This study adds to the knowledge of anatomical brainstem representation of VEMP.

Medial vestibulospinal tract lesions impair sacculo-collic reflexes

The medial vestibulospinal tract (VST) is known to mediate the vestibular-evoked myogenic potential (VEMP) in the contracting sternocleidomastoid muscle (SCM). To determine whether disruption of the medial VST in the medulla impairs formation of VEMP, we measured VEMP in 14 patients with medial medullary infarction (MMI). VEMP was induced by a short tone burst and was recorded in contracting SCM while patients turned their heads forcefully to the contralateral side against resistance. Normative data were obtained from 47 healthy volunteers. Seven patients (50%) had abnormal VEMP in the side of the MMI lesion, absent in two, decreased in four, and delayed in two. One patient showed both decreased and delayed response. Of the seven patients with abnormal VEMP, five had the lesions that extended to the dorsal tegmentum while five of the seven patients with normal VEMP showed restricted anteromedial lesions mainly involving the pyramids. Spontaneous nystagmus (4/7, 57%), gaze-evoked nystagmus (6/7, 86%), and ocular tilt reaction/tilt of the subjective visual vertical (4/7, 57%) were frequently observed in the patients with abnormal VEMP. The abnormal VEMP in patients with infarctions involving the medullary tegmentum supports that VEMP is mediated by the medial VST descending within the medial longitudinal fasciculus.

현훈을 동반하지 않은 돌발성 난청에서 전정유발근전위의 임상적 의의

Background: We investigated saccular damage in sudden sensorineural hearing loss patients without vertigo through vestibular evoked myogenic potentials (VEMP). Methods: Thirty patients (male: 9, female: 21) with idiopathic sudden sensorineural hearing loss (ISSHL) without vertigo were enrolled in this study. We identified VEMP in patients with ISSHL and analyzed the association of VEMP with initial hearing threshold, each threshold according to frequency, the type of audiogram, and the hearing recovery. Results: Among thirty patients, twenty six patients (80.7%) showed normal VEMP wave. Patients with hearing loss less than 55 dB showed significantly higher abnormal VEMP rates than the patients with 55 dB or more with frequencies at 250 and 1,000 Hz (p&lt; 0.05). According to the type of audiogram, and the hearing recovery, we found no significant differences. Conclusions: Most of sudden idiopathic sensorineural hearing loss patients without vertigo showed normal VEMP wave. In particular cases with a less than 55 dB hearing loss with a frequency at 250 or 1,000 Hz could have a high rate of abnormal VEMP. These findings suggest that these patients are associated with subclinical disturbances of the vestibular system especially of the saccule and may develop Meniere disease later. (J Clinical Otolaryngol 2009;20:201–206)