New perspectives on vestibular evoked myogenic potentials. Curr Opin Neurol. 2013;26:74-80. [PMID: 23254558 DOI: 10.1097/wco.0b013e32835c5ef3]

The History of Superior Semicircular Canal Dehiscence: A Bibliometric Analysis

OBJECTIVE

The treatment and understanding of superior semicircular canal dehiscence (SSCD) has seen significant developments over the past 25 years. Bibliographic analysis can provide insight into the evolution of research as well as highlight emerging areas. Reviewing a large volume of publications provides valuable insights into the citation patterns and collaborations of research groups. This study seeks to offer a comprehensive historical overview of SSCD and leading authors.

DATABASE REVIEWED

Web of Science Core Collection.

METHODS

A bibliometric analysis of the current literature on SSCD was conducted. A performance analysis and science mapping of the top 100 most cited articles was completed using a citation analysis. Two independent reviewers evaluated articles for relevance and adjugated by a third reviewer. Author and institution networks were examined.

RESULTS

Seven hundred ninety-one articles on the topic of SSCD were identified. The top 100 articles spanned over 23 years from 1998 to 2019 and were published in 30 different journals. The top 100 articles were cited 8253 times in literature. The document contents revealed 233 keywords and 238 author keywords. The articles were authored by a total of 291 authors, with only 4 single-authored documents.

CONCLUSIONS

SSCD has been highly researched in aspects of symptomatology, diagnosis, and treatment, as indicated by many highly cited articles that relate. However, the production of highly cited articles on SSCD displays a significant decrease after 2013, with only 17 of the top cited articles published since then.

The impact of vestibular dysfunction on falls and postural instability in individuals with type 2 diabetes with and without diabetic polyneuropathy

Aim

This study aimed to determine the association between vestibular dysfunction, falls, and postural instability in individuals with type 2 diabetes (T2D) compared to healthy control individuals and to examine the impact of diabetic polyneuropathy (DPN).

Methods

This cross-sectional study included individuals with T2D with DPN (n = 43), without DPN (n = 32), and healthy controls (n = 32). Cervical and ocular vestibular evoked myogenic potentials (VEMP) were recorded, and latencies and amplitudes were determined. DPN was diagnosed based on nerve conduction studies and clinical scores. Postural instability was examined using a static posturographic balance system and calculated as an instability index (ST). Falls were recorded retrospectively during the past year. Group comparisons were conducted by using univariate and bivariate statistics.

Results

Individuals with T2D experienced more falls than healthy controls (T2D with DPN n = 12[38%], T2D without DPN n = 15[35%], controls n = 5[16%], p = 0.04). Individuals with T2D had decreased postural stability, T2D with DPN, ST (median of 52[iqi = 33; 77]), T2D without DPN, ST (median of 31[iqi = 24; 39]), controls ST (median of 26[iqi = 19; 33], p = 0.01), when comparing all three groups. Individuals with T2D had a greater number of no-responses in oVEMP compared to controls (T2D with DPN, n = 15[46.9%] T2D without DPN n = 25[58.1%], controls n = 9[28.1%], p = 0.04). No difference was found in cVEMP and oVEMP amplitudes in any of the groups. Irrespectively of DPN, fallers with T2D had decreased oVEMP and cVEMP latencies on the right ears, when comparing to non-fallers, respectively, n10 (fallers [median of 16, iqi=15;19 ms.] vs. non-fallers [median of 25 iqi=16;35 ms]); p13 (fallers [median of 16, iqi=15;17 ms.] vs. non-fallers [median of 15, iqi=8;16 ms.], p < 0.05).

Conclusion

Falls and postural instability were more frequent in individuals with T2D compared to healthy controls. Fallers with T2D had vestibular end-organ impairments based on the oVEMP and cVEMP latencies on the right but not the left ears, irrespective of DPN. Individuals with T2D had more frequent no-response of the oVEMP, indicating impaired vestibular nerve function.

Vestibular motor control

The vestibular system is an essential sensory system that generates motor reflexes that are crucial for our daily activities, including stabilizing the visual axis of gaze and maintaining head and body posture. In addition, the vestibular system provides us with our sense of movement and orientation relative to space and serves a vital role in ensuring accurate voluntary behaviors. Neurophysiological studies have provided fundamental insights into the functional circuitry of vestibular motor pathways. A unique feature of the vestibular system compared to other sensory systems is that the same central neurons that receive direct input from the afferents of the vestibular component of the 8th nerve can also directly project to motor centers that control vital vestibular motor reflexes. In turn, these reflexes ensure stabilize gaze and the maintenance of posture during everyday activities. For instance, a direct three-neuron pathway mediates the vestibulo-ocular reflex (VOR) pathway to provide stable gaze. Furthermore, recent studies have advanced our understanding of the computations performed by the cerebellum and cortex required for motor learning, compensation, and voluntary movement and navigation. Together, these findings have provided new insights into how the brain ensures accurate self-movement during our everyday activities and have also advanced our knowledge of the neurobiological mechanisms underlying disorders of vestibular processing.

Vestibular function in children with cochlear implant: Impact and evaluation

Over the last 30 years, cochlear implant (CI) has been dedicated to improving the rehabilitation of hearing impairments. However, CI has shown potential detrimental effects on vestibular function. For children, due to atypical symptoms and difficulty in cooperating with vestibular function tests, systematic and objective assessments of vestibular function with CI have been conducted sparsely. This review focuses on the impact of vestibular function in children with CI and summarized the evaluation of vestibular function in children. In addition, some recommended strategies are summarized and proposed.

Impact of Cochlear Implantation on Canal and Otolith Function

OBJECTIVE

To quantify the impact of cochlear implantation (CI) on all five vestibular end-organs and on subjective ratings of post-CI dizziness.

METHODS

Seventy-two patients undergoing unilateral CI were recruited for the study. All participants completed pre- and post-CI three-dimensional video head-impulse tests (3D vHITs) to assess semicircular-canal (SC) function, air- and bone-conducted (AC and BC) cervical and ocular vestibular-evoked myogenic potentials (cVEMPs and oVEMPs) to assess otolith-function and the dizziness handicap inventory (DHI) to measure self-perceived disability.

RESULTS

Nineteen percent of patients reported new or worsened dizziness postsurgery. Post-CI abnormalities (new lesions and significant deteriorations) were seen in the AC cVEMP (48%), AC oVEMP (34%), BC cVEMP (10%), and BC oVEMP (7%); and lateral (L) (17%), posterior (P) (10%), and anterior (A) (13%) SC vHITs. CI surgery was more likely to affect the AC cVEMP compared with the other tests (χ2 test, p < 0.05). Fifty percent of patients reported no dizziness pre- and postsurgery. In the implanted ear, normal pre-CI vHIT gain was preserved in lateral semicircular canal (LSC) (69%), anterior semicircular canal (ASC) (74%), and posterior semicircular canal (PSC) (67%), and normal reflex amplitudes were found in AC cVEMP (25%), AC oVEMP (20%), BC cVEMP (59%), and BC oVEMP (74%). Statistically significant decreases were observed in LSC vHIT gain, AC cVEMP amplitude, and AC oVEMP amplitude postsurgery (p < 0.05). There was a significant moderate positive correlation between change in DHI scores and the summed vestibular deficit postsurgery (r(51) = 0.38, p < 0.05).

CONCLUSION

CI can impact tests that assess all five vestibular end-organs and subjective ratings of dizziness. These results support pre and post-surgical vestibular testing and assist preoperative counseling and candidate selection.

The Impact of Optical Illusions on the Vestibular System

Background and Objectives

Balance control is maintained in stationary and dynamic conditions, with coordinated muscle responses generated by somatosensory, vestibular, and visual inputs. This study aimed to investigate how the vestibular system is affected in the presence of an optical illusion to better understand the interconnected pathways of the visual and vestibular systems.

Subjects and Methods

The study involved 54 young adults (27 males and 27 females) aged 18-25 years. The recruited participants were subjected to the cervical vestibular evoked myogenic potentials (cVEMP) test and video head impulse test (vHIT). The cVEMP and vHIT tests were performed once each in the absence and presence of an optical illusion. In addition, after each test, whether the individuals felt balanced was determined using a questionnaire.

Results

cVEMP results in the presence of the optical illusion showed shortened latencies and increased amplitudes for the left side in comparison to the results in the absence of the optical illusion (p≤0.05). When vHIT results were compared, it was seen that the right lateral and bilateral anterior canal gains were increased, almost to 1.0 (p<0.05).

Conclusions

It is thought that when the visual-vestibular inputs are incompatible with each other, the sensory reweighting mechanism is activated, and this mechanism strengthens the more reliable (vestibular) inputs, while suppressing the less reliable (visual) inputs. As long as the incompatible condition persists, the sensory reweighting mechanism will continue to operate, thanks to the feedback loop from the efferent vestibular system.

Independent Measures of Utricular Function: Ocular Vestibular Evoked Myogenic Potentials Do Not Correlate With Subjective Visual Vertical or Fundus Photographic Binocular Cyclorotation

Ocular vestibular evoked myogenic potentials (oVEMPs), subjective visual vertical (SVV), and fundus photographically measured binocular cyclorotation (BCR) are diagnostic tests to assess utricular function in patients with vertigo or dizziness. In 138 patients with chronic vertigo or dizziness, we asked whether the asymmetry ratio of oVEMP (normal, right side pathological, left side pathological) could predict the SVV deviation (normal, rightward deviation, leftward deviation) or BCR (normal, cyclorotation to the right, cyclorotation to the left). There was no correlation between oVEMP and SVV and between oVEMP and BCR, while SVV and BCR correlated highly. Although both oVEMP and SVV measure aspects of utricular function, our findings demonstrate that oVEMP and SVV are not redundant and may reflect different utricular pathologies. The role of fundus photographic BCR may be relegated to only confirm unclear SVV results in vestibular diagnostic workup.

Vestibular status: A missing factor in our understanding of brain reorganization in deaf individuals

The brain of deaf people is definitely not just deaf, and we have to reconsider what we know about the impact of hearing loss on brain development in light of comorbid vestibular impairments.

Selective Asymmetry of Ocular Vestibular-Evoked Myogenic Potential in Patients with Acute Utricular Macula Loss

OBJECTIVES

We retrospectively evaluated a chart review of 3,525 patients evaluated for any acute disturbance. A total of 1,504 patients with acute vestibular syndrome (AVS) received an instrumental vestibular assessment within 72 h from the onset of the symptoms evaluated using simultaneously a combination of ocular vestibular-evoked myogenic potential (oVEMPs), cervical vestibular-evoked myogenic potential (cVEMPs), video head-impulse test (vHIT), and subjective visual vertical (SVV) were included in this study.

MATERIALS AND METHODS

A total of 41 patients with AVS that showed a normal horizontal canal function tested with vHIT, a normal cVEMP function, unilaterally reduced or absent oVEMP n10, and an altered SVV were enrolled.

RESULTS

We found that although these patients referred acute vertigo and presented spontaneous nystagmus, they showed physiological values of vHIT and a normal saccular function, as shown by symmetrical cVEMPs.

CONCLUSION

Our findings support the hypothesis that a percentage of patients evaluated during an AVS using an instrumental vestibular assessment could present selective utricular macula dysfunction.

Association of cervical vestibular-evoked myogenic potential tuning property test results with MRI findings of endolymphatic hydrops in Meniere's disease

PURPOSE

To examine the concordance between cervical vestibular-evoked myogenic potential (cVEMP) tuning property test results and MRI findings of endolymphatic hydrops (EH).

METHODS

Fourteen subjects (age 24-76 years) that had been diagnosed with unilateral definite Meniere's disease (MD) (N = 8) or unilateral probable MD (N = 6) were enrolled. All of the subjects underwent cVEMP tests (using 500 Hz and 1000 Hz tone bursts), pure-tone audiometry, and gadolinium-enhanced 3 T-MRI. To examine tuning properties of cVEMP, the 500-1000 Hz amplitude ratio was calculated as the SLOPE. The results of the cVEMP tuning property test results were compared with EH-related MRI findings.

RESULTS

EH positivity in both the cochlea and vestibule on MRI was observed in 7 of the 8 affected ears of definite MD and 3 of the 6 affected ears of probable MD, although it was only in one of the 14 unaffected ears. EH(+) or no response (NR) in cVEMP tuning property test was significantly associated with EH positivity on MRI, while EH(-) in the cVEMP tuning property test was significantly associated with EH-negativity on MRI (p = 0.0016 Fisher's exact test test).

CONCLUSION

EH(+) or NR in the cVEMP tuning property test correspond well to EH positivity in the MRI findings. The cVEMP tuning property test is useful for screening and following up EH.

Functional Integrity of the Inferior Vestibular Nerve and Posterior Canal BPPV

The functional integrity of the inferior vestibular nerve (IVN) may be evaluated by the cervical vestibular evoked myogenic potential (cVEMP) response, which requires signal transmission via the nerve. As functional integrity of the IVN innervating the posterior semicircular canal is required to produce the typical positioning vertigo and nystagmus characterizing posterior canal benign paroxysmal positional vertigo (PCBPPV), we hypothesized that normal cVEMPs would be found in most PCBPPV patients. Twenty-four PCBPPV patients participated in a prospective cohort study. All were treated by canal repositioning maneuver and had air-conduction cVEMP and videonystagmography (VNG). Follow-up evaluations including history and otoneurological bedside examination were carried out 1, 3, 6, and 12 months after the initial treatment. At the last follow-up, the patients filled the Dizziness Handicap Inventory (DHI) questionnaire. Normal cVEMPs were recorded in 19 (79%) and were absent in 5 (21%) of the subjects. The average DHI in the patients with normal cVEMP was 16.42 ± 17.99 vs. 0.4 ± 0.89 among those with pathological cVEMP (p < 0.04, Mann-Whitney test). Thirteen (54%) patients experienced recurrent PCBPPV (rPCBPPV). The average DHI score was significantly higher among patients having recurrence (22.15 ± 18.61) when compared to those with complete cure (2.36 ± 5.98; p < 0.003, Mann-Whitney test). Ten (77%) of the subjects with rPCBPPV had normal and 3 (23%) had pathological cVEMP as compared to 9 (82%) and 2 (18%) subjects in the non-recurrent (nrPCBPPV) group (Fisher's exact test-not significant). cVEMP p13 and n23 wave latencies and amplitudes, inter-aural differences in p13-n23 peak-to-peak amplitudes, and response thresholds did not differ between the groups. No differences were found between the rPCBBPV and nrPCBBPV groups in VNG caloric lateralization and directional preponderance values. We have found that in most cases, PCBPPV symptoms and signs are associated with normal cVEMP response supporting the role of IVN functional integrity. The absent cVEMPs in the minority of patients, although having similar clinical presentation, raise the possibility that the ipsilateral saccule is affected by the same pathology causing degeneration of the utricle macula. Alternatively, lacking inhibitory stimuli from the involved ipsilateral utricle or partial degeneration of the IVN and ganglion could explain the diminished cVEMP response. Clinical Trial Registration: The study was registered in ClinicalTrials.gov Internet site (study ID-NCT01004913; https://clinicaltrials.gov/ct2/show/NCT01004913?cond=BPPV&cntry=IL&draw=2&rank=3).

Diagnosing Myasthenia Gravis With Repetitive Ocular Vestibular Evoked Myogenic Potentials

Timely and accurate diagnosis of myasthenia gravis, particularly in patients with fluctuating, isolated ocular involvement, remains challenging. Serological antibody testing and repetitive nerve stimulation of peripheral muscles usually have low sensitivity in these patients. Edrophonium testing may cause adverse events, single-fiber electromyography (SFEMG) is time-consuming and both tests are often unavailable outside specialized institutions. Repetitive ocular vestibular evoked myogenic potential (roVEMP) stimulation has recently been introduced to facilitate the diagnosis of myasthenia gravis. Similar to repetitive nerve stimulation, roVEMPs detect muscle decrements with the benefit of being non–invasive and allowing for direct measurement of the extraocular muscles. This review summarizes the clinical evidence of the diagnostic value of roVEMP for myasthenia. Prospective clinical trials have demonstrated high sensitivity and specificity. RoVEMPs are of particular interest in challenging myasthenia subgroups with isolated ocular involvement, negative serology, and/or negative conventional electrophysiological results. Optimal roVEMP repetition rates of 20–30 Hz have been identified. This promising novel diagnostic tool merits further attention and investigation to establish its value as a clinical test for myasthenia.

Validating the Utility of High Frequency Ocular Vestibular Evoked Myogenic Potential Testing in the Diagnosis of Superior Semicircular Canal Dehiscence

INTRODUCTION

Ocular vestibular evoked myogenic potential (oVEMP) is a diagnostic test employed in the evaluation of superior semicircular canal dehiscence (SSCD) syndrome. Previous work showed that the presence of the n10 component of oVEMP at 4000 Hz was diagnostic of SSCD with perfect sensitivity and specificity of 1.0 in a series of 22 patients. This study sought to validate the diagnostic accuracy of high-frequency oVEMP with comparison to 500 Hz oVEMP and cervical vestibular evoked myogenic potential (cVEMP) in a larger series of patients.

METHODS

Retrospective chart review of 171 patients with clinical symptoms consistent with SSCD who underwent oVEMP and cVEMP testing. Dehiscence of the superior semicircular canal (SCC) on high-resolution computed tomography (CT) imaging of the temporal bone was used to identify cases of likely SSCD. The presence or absence of 4000 Hz oVEMP n10 responses, increased amplitude of 500 Hz oVEMP responses, and reduced threshold of 500 Hz cVEMP responses were identified for each patient.

RESULTS

SCC dehiscence was identified by CT imaging in 48 of 171 patients with symptoms consistent with SSCD. High-frequency oVEMP testing at 4000 Hz elicited a n10 response in 40 of 48 (83.3%) of patients and was present in 48 of 171 (28.1%) patients overall. The corresponding sensitivity was 0.83, specificity was 0.93, positive predictive value was 0.83, and negative predictive value was 0.93. oVEMP and cVEMP testing at 500 Hz was less accurate with sensitivity of 0.62 and 0.64, respectively, and specificity of 0.73 and 0.73, respectively.

CONCLUSION

The presence of a 4000 Hz oVEMP n10 response was predictive of SSC dehiscence on CT imaging among patients with symptoms consistent with SSCD with sensitivity of 0.83, specificity of 0.93, positive predictive value of 0.83, and negative predictive value of 0.93. A negative finding strongly rules out SSCD. High-frequency oVEMP was more accurate than 500 Hz oVEMP or cVEMP.

When the Room Is Spinning: Experience of Vestibular Neuritis by a Neurotologist

Vestibular neuritis (VN) is the most common cause of acute prolonged spontaneous vertigo, and is characterized by acute unilateral vestibular hypofunction, probably due to inflammation of the vestibular nerve. VN is diagnosed at the bedside when there is spontaneous horizontal-torsional nystagmus beating away from the side of the lesion, abnormal head impulse tests for the semicircular canals involved on the lesion side, and when other neurological symptoms and signs are absent. Here, as a neuro-otologist, I describe my experience during an attack of VN and discuss how it may help physicians to better understand why and what a patient feels during attacks of vertigo.

Vestibular evoked myogenic potentials in patients with diabetes mellitus

Although the exact mechanism and most involved region of the vestibular system have not yet been fully clarified, vestibular dysfunction has been demonstrated in patients with diabetes mellitus (DM). Vestibular evoked myogenic potential (VEMP) is a short latency electromyographic response to sound or vibration stimuli that may reflect otolith organ or related reflex functions. Since its first description in 1992, VEMP has become a significant part of the vestibular test battery as an objective measurement tool. In diabetic patients, VEMP responses have been studied in order to determine any otolith organ or related reflex dysfunctions. Here, we review the literature with regard to VEMP findings representing any peripheral vestibular end-organ dysfunction in patients with DM. Distinctive vestibular end-organ impairments seem to be demonstrated in patients with DM either with or without DNP via objective vestibular testing tools including VEMP recordings according to relevant studies. However, further studies with larger sample sizes are required to reveal the more definitive findings of VEMP recordings regarding the vestibular pathologies in patients with DM.

Vection in virtual reality modulates vestibular-evoked myogenic potentials

The popularity of virtual reality (VR) has increased rapidly in recent years. While significant technological advancements are apparent, a troublesome problem with VR is that between 20% and 80% of users will experience unpleasant side effects such as nausea, disorientation, blurred vision and headaches-a malady known as Cybersickness. Cybersickness may be caused by a conflict between sensory signals for self-motion: while vision signals that the user is moving in a certain direction with certain acceleration, the vestibular organs provide no corroborating information. To resolve the sensory conflict, vestibular cues may be down-weighted leading to an alteration of how the brain interprets actual vestibular information. This may account for the frequently reported after-effects of VR exposure. Here, we investigated whether exposure to vection in VR modulates vestibular processing. We measured vestibular-evoked myogenic potentials (VEMPs) during brief immersion in a vection-inducing VR environment presented via head-mounted display. We found changes in VEMP asymmetry ratio, with a substantial increase in VEMP amplitude recorded on the left sternocleidomastoid muscle following just one minute of exposure to vection in VR. Our results suggest that exposure to vection in VR modulates vestibular processing, which may explain common after-effects of VR.

Assessment of Subjective Visual Vertical (SVV) Using the "Bucket Test" and the Virtual SVV System

OBJECTIVE

The purpose of this study was to describe the variability and test-retest reliability of a commercially available subjective visual vertical (SVV) system known as Virtual SVV (Interacoustics). In addition, the study aimed to compare the reliability of the Virtual system with a previously established bucket test of SVV.

STUDY DESIGN

Fifteen participants with normal hearing, normal middle ear function, and normal utricular function were included in the study. Each participant underwent static SVV testing using both the Virtual system and the bucket test. Subjects completed 2 testing sessions to determine test-retest reliability. For each test, data were collected with the head at 0°, tilted 45° to the right, and tilted 45° to the left.

SETTING

This study was conducted in a balance function laboratory embedded in a large, tertiary care otology clinic.

RESULTS

The mean SVV values obtained with the Virtual system were within 1°-2° from 0 with the head positioned at 0°, which is in agreement with many other studies of SVV with the head at 0° (Akin & Murnane, 2009; Halmagyi & Curthoys, 1999; Zwergal, Rettinger, Frenzel, Dieterich, & Strupp, 2009). Using the intraclass correlation coefficient, test-retest reliability of the Virtual system was excellent in the 45° left position and fair to good in the 45° right and 0° position. Test-retest reliability of the bucket test was poor in all head positions.

CONCLUSIONS

The Virtual system is a more reliable measure of static SVV than the bucket test. Therefore, the Virtual system could be utilized as a screening device for utricular dysfunction in busy clinical settings.

μVEMP: A Portable Interface to Record Vestibular Evoked Myogenic Potentials (VEMPs) With a Smart Phone or Tablet

Background: Cervical VEMPs and ocular VEMPs are tests for evaluating otolith function in clinical practice. We developed a simple, portable and affordable device to record VEMP responses on patients, named μVEMP. Our aim was to validate and field test the new μVEMP device. Methods: We recorded cervical VEMPs and ocular VEMPs in response to bone conducted vibration using taps tendon hammer to the forehead (Fz) and to air conducted sounds using clicks. We simultaneously recorded VEMP responses (same subject, same electrode, same stimuli) in three healthy volunteers (2 females, age range: 29-57 years) with the μVEMP device and with a standard research grade commercial (CED) system used in clinics. We also used the μVEMP device to record VEMP responses from six patients (6 females, age mean±SD: 50.3 ± 20.8 years) with classical peripheral audio-vestibular diseases (unilateral vestibular neuritis, unilateral neurectomy, bilateral vestibular loss, unilateral superior canal dehiscence, unilateral otosclerosis). Results: The first part of this paper compared the devices using simultaneous recordings. The average of the concordance correlation coefficient was rc = 0.997 ± 0.003 showing a strong similarity between the measures. VEMP responses recorded with the μVEMP device on patients with audio-vestibular diseases were similar to those typically found in the literature. Conclusions: We developed, validated and field tested a new device to record ocular and cervical VEMPs in response to sound and vibration.This new device is portable (powered by a phone or tablet) with pocket-size dimensions (105 × 66 × 27 mm) and light weight (150 g). Although further studies and normative data are required, our μVEMP device is simpler (easier to use) and potentially more accessible than standard, commercially available equipment.

Vestibular-Evoked Myogenic Potentials in Bilateral Vestibulopathy

Bilateral vestibulopathy (BVP) is a chronic condition in which patients have a reduction or absence of vestibular function in both ears. BVP is characterized by bilateral reduction of horizontal canal responses; however, there is increasing evidence that otolith function can also be affected. Cervical and ocular vestibular-evoked myogenic potentials (cVEMPs/oVEMPs) are relatively new tests of otolith function that can be used to test the saccule and utricle of both ears independently. Studies to date show that cVEMPs and oVEMPs are often small or absent in BVP but are in the normal range in a significant proportion of patients. The variability in otolith function is partly due to the heterogeneous nature of BVP but is also due to false negative and positive responses that occur because of the large range of normal VEMP amplitudes. Due to their variability, VEMPs are not part of the diagnosis of BVP; however, they are helpful complementary tests that can provide information about the extent of disease within the labyrinth. This article is a review of the use of VEMPs in BVP, summarizing the available data on VEMP abnormalities in patients and discussing the limitations of VEMPs in diagnosing bilateral loss of otolith function.

Effects of motion sickness severity on the vestibular-evoked myogenic potentials

BACKGROUND

Motion sickness is a common debilitating condition associated with both actual and perceived motion. Despite the commonality, little is known about the underlying physiological mechanisms. One theory proposes that motion sickness arises from a mismatch between reality and past experience in vertical motions. Physiological tests of the vestibular system, however, have been inconclusive regarding the underlying pathogenesis. Cervical vestibular-evoked myogenic potentials (cVEMPs) arise from the saccule, which responds to vertical motion. If vertical motion elicits motion sickness, the cVEMP should be affected.

PURPOSE

The purpose of this investigation was to determine if cVEMP characteristics differ among individuals with a range of motion sickness susceptibility from negligible to severe. The hypothesis was that individuals with high susceptibility would have larger cVEMP amplitudes and shorter cVEMP latencies relative to those who are resistant to motion sickness.

RESEARCH DESIGN

The study had two parts. The first was quasi-experimental in which participants comprised three groups based on susceptibility to motion sickness (low, mild-moderate, high) as identified on the short version of the Motion Sickness Susceptibility Questionnaire (MSSQ-S). The second part of the study was correlational and evaluated the specific relationships between the degree of motion sickness susceptibility and characteristics of the VEMPs.

STUDY SAMPLE

A total of 24 healthy young adults (ages 20-24 yr) were recruited from the university and the community without regard to motion sickness severity.

DATA COLLECTION AND ANALYSIS

Participants took the MSSQ-S, which quantifies susceptibility to motion sickness. The participants had a range of motion sickness susceptibility with MSSQ raw scores from 0.0-36.6, which correspond to percent susceptibility from 0.0-99.3%. VEMPs were elicited by 500 Hz tone-bursts monaurally in both ears at 120 dB pSPL. MSSQ-S percent scores were used to divide the participants into low, mild-moderate, and high susceptibility groups. A fixed general linear model with repeated-measures analysis of variance tested cVEMP characteristics for the susceptibility groups (between participants) and ears (within participants). A univariate analysis of variance tested the cVEMP interaural amplitudes across groups. The second analysis was a regression of the severity of motion sickness in percent on cVEMP characteristics. Significance was defined as p < 0.05.

RESULTS

Participants in the high susceptibility group had significantly higher cVEMP amplitudes than those in the low susceptibility group. cVEMP amplitudes did not differ between ears, and latencies did not differ between the two groups or between ears. Regression analysis on MSSQ-S percent susceptibility by VEMP amplitudes revealed a best-fit cubic function in both ears, with r(2) values of more than 42%. The interaural asymmetry ratio was negatively associated with motion sickness susceptibility (r(2) = 0.389).

CONCLUSIONS

The current study is the first to report that greater susceptibility to motion sickness is associated with larger cVEMP amplitudes and lower interaural cVEMP asymmetries. Larger interaural asymmetries in cVEMPs did not promote motion sickness susceptibility. The cVEMP findings implicate the saccule and its neural pathways in the production of motion sickness and are consistent with the theory that vertical motions elicit motion sickness. Motion sickness susceptibility may contribute to the variability in normative cVEMP amplitudes.

Paroxysmal positional vertigo despite complete vestibular impairment: the role of instrumental assessment

Lindsay-Hemenway syndrome is characterised by a posterior canal benign paroxysmal positional vertigo following a partial unilateral vestibular loss affecting the same side. The syndrome is caused by damage of structures innervated by the superior division of the vestibular nerve and perfused by the anterior vestibular artery; the detached otoconia can cause vertigo in the still intact posterior semicircular canal. The most recent vestibular instrumental techniques allow reaching an accurate topodiagnosis in case of peripheral vestibular failure. We report on two cases of Lindsay-Hemenway syndrome despite complete vestibular failure demonstrated by vestibular instrumental assessment. After making some critical considerations on these findings, we underline the importance of not disregarding the diagnosis of paroxysmal positional vertigo in an established complete labyrinthine loss of function.

Comparison of Different Electrode Configurations for the oVEMP With Bone-Conducted Vibration

OBJECTIVES

This study was performed to compare three electrode configurations for the ocular vestibular evoked myogenic potentials (oVEMPs)-"standard," "sternum," and "nose"-by making use of bone-conducted stimuli (at the level of Fz with a minishaker). In the second part, we compared the test-retest reliability of the standard and nose electrode configuration on the oVEMP parameters.

DESIGN

This study had a prospective design. Fourteen healthy subjects participated in the first part (4 males, 10 females; average age = 23.4 (SD = 2.6) years; age range 19.9 to 28.3 years) and second part (3 males, 11 females; average age = 22.7 (SD = 2.4) years; age range 20.0 to 28.0 years) of the study. OVEMPs were recorded making use of a hand-held bone conduction vibrator (minishaker). Tone bursts of 500 Hz (rise/fall time = 2 msec; plateau time = 2 msec; repetition rate = 5.1 Hz) were applied at a constant stimulus intensity level of 140 dB FL.

RESULTS

PART 1: The n10-p15 amplitude obtained with the standard electrode configuration (mean = 15.8 μV; SD = 6.3 μV) was significantly smaller than the amplitude measured with the nose (Z = -3.3; p = 0.001; mean = 35.0 μV; SD = 19.1 μV) and sternum (Z = -3.3; p = 0.001; mean = 27.1 μV; SD = 12.2 μV) electrode configuration. The p15 latency obtained with the nose electrode configuration (mean = 14.2 msec; SD = 0.54 msec) was significantly shorter than the p15 latency measured with the standard (Z = -3.08; p = 0.002) (mean = 14.9 msec; SD = 0.75 msec) and sternum (Z = -2.98; p = 0.003; mean = 15.4 msec; SD = 1.07 msec) electrode configuration. There were no differences between the n10 latencies of the three electrode configurations. The 95% prediction intervals (given by the mean ± 1.96 * SD) for the different interocular ratio values were [-41.2; 41.2], [-37.2; 37.2], and [-25.9; 25.9] for standard, sternum, and nose electrode configurations, respectively. PART 2: Intraclass correlation (ICC) values calculated for the oVEMP parameters obtained with the standard electrode configuration showed fair to good reliability for the parameters n10-p15 amplitude (ICC = 0.51), n10 (ICC = 0.52), and p15 (ICC = 0.60) latencies. The ICC values obtained for the parameters acquired with the nose electrode configuration demonstrated a poor reliability for the n10 latency (ICC = 0.37), a fair to good reliability for the p15 latency (ICC = 0.47) and an excellent reliability for the n10-p15 amplitude (ICC = 0.85).

CONCLUSIONS

This study showed the possible benefits from alternative electrode configurations for measuring bone-conducted-evoked oVEMPs in comparison with the standard electrode configuration. The nose configuration seems promising, but further research is required to justify clinical use of this placement.

Current diagnostic procedures for diagnosing vertigo and dizziness

Vertigo is a multisensory syndrome that otolaryngologists are confronted with every day. With regard to the complex functions of the sense of orientation, vertigo is considered today as a disorder of the sense of direction, a disturbed spatial perception of the body. Beside the frequent classical syndromes for which vertigo is the leading symptom (e.g. positional vertigo, vestibular neuritis, Menière’s disease), vertigo may occur as main or accompanying symptom of a multitude of ENT-related diseases involving the inner ear. It also concerns for example acute and chronic viral or bacterial infections of the ear with serous or bacterial labyrinthitis, disorders due to injury (e.g. barotrauma, fracture of the oto-base, contusion of the labyrinth), chronic-inflammatory bone processes as well as inner ear affections in the perioperative course. In the last years, diagnostics of vertigo have experienced a paradigm shift due to new diagnostic possibilities. In the diagnostics of emergency cases, peripheral and central disorders of vertigo (acute vestibular syndrome) may be differentiated with simple algorithms. The introduction of modern vestibular test procedures (video head impulse test, vestibular evoked myogenic potentials) in the clinical practice led to new diagnostic options that for the first time allow a complex objective assessment of all components of the vestibular organ with relatively low effort. Combined with established methods, a frequency-specific assessment of the function of vestibular reflexes is possible. New classifications allow a clinically better differentiation of vertigo syndromes. Modern radiological procedures such as for example intratympanic gadolinium application for Menière’s disease with visualization of an endolymphatic hydrops also influence current medical standards. Recent methodical developments significantly contributed to the possibilities that nowadays vertigo can be better and more quickly clarified in particular in otolaryngology.

What the electrical impedance can tell about the intrinsic properties of an electrodynamic shaker

Small electrodynamic shakers are becoming increasingly popular for diagnostic investigations of the human vestibular system. More specifically, they are used as mechanical stimulators for eliciting a vestibular evoked myogenic potential (VEMP). However, it is largely unknown how shakers perform under typical measurement conditions, which considerably differ from the normal use of a shaker. Here, it is shown how the basic properties of a shaker can be determined without requiring special sensors such as accelerometers or force gauges. In essence, the mechanical parts of the shaker leave a signature in the electrical impedance, and an interpretation of this signature using a simple model allows for drawing conclusions about the properties of the shaker. The theory developed (which is quite general so that it is usable also in other contexts) is applied to experimental data obtained for the minishaker commonly used in VEMP measurements. It is shown that the experimental conditions substantially influence the properties of the shaker. Relevant factors are, in particular, the spatial orientation of the shaker (upright, horizontal or upside-down) and the static force acting on the table of the shaker (which in a real measurement corresponds to the force by which the shaker is pressed against the test person's head). These results underline the desirability of a proper standardization of VEMP measurements. Direct measurements of displacement and acceleration prove the consistency of the conclusions derived from the electrical impedance.

Vestibular evoked myogenic potentials and video head impulse test in patients with vertigo, dizziness and imbalance

The aim of this study was to compare vestibular evoked myogenic potentials (VEMP) and video head impulse test (vHIT) results in patients presenting with vertigo and dizziness. We retrospectively analyzed data of all patients with the chief complaint of vertigo, dizziness, or imbalance that underwent VEMP and vHIT from January 2015 to January 2016. A total of 117 patients (73 females, mean age 53.92±16.76) fulfilled inclusion criteria: group 1 included patients with the final diagnosis of vestibular neuritis (VN) (N=31 (16 right and 15 left VN)), group 2 included patients with the final diagnosis of vertigo of central origin (N=23) and group 3 included patients with the final diagnosis of unspecified dizziness (N=63). There was significant correlation between oVEMP asymmetry and asymmetry of the lateral canals 60ms gains on vHIT (r=0.225, p=0.026). Significant correlation between oVEMP and vHIT asymmetry was present in VN patients (r=0.749, p<0.001), while no correlation was found in the groups 2 and 3. oVEMP and vHIT lateral canals asymmetries were significantly greater in patients with vestibular neuritis. Furthermore, positive correlations of oVEMP amplitudes with 60ms gain of the lateral semicircular canal and slope of the anterior semicircular canal on vHIT, and cVEMP with slope of the posterior semicircular canal on the vHIT were found. These changes were significantly more pronounced in patients with vestibular neuritis. In conclusion, VEMPs and vHIT data should be used complementarily; asymmetry on both tests strongly supports peripheral vestibular system involvement.

The new vestibular stimuli: sound and vibration-anatomical, physiological and clinical evidence

The classical view of the otoliths-as flat plates of fairly uniform receptors activated by linear acceleration dragging on otoconia and so deflecting the receptor hair bundles-has been replaced by new anatomical and physiological evidence which shows that the maculae are much more complex. There is anatomical spatial differentiation across the macula in terms of receptor types, hair bundle heights, stiffness and attachment to the overlying otolithic membrane. This anatomical spatial differentiation corresponds to the neural spatial differentiation of response dynamics from the receptors and afferents from different regions of the otolithic maculae. Specifically, receptors in a specialized band of cells, the striola, are predominantly type I receptors, with short, stiff hair bundles and looser attachment to the overlying otoconial membrane than extrastriolar receptors. At the striola the hair bundles project into holes in the otolithic membrane, allowing for fluid displacement to deflect the hair bundles and activate the cell. This review shows the anatomical and physiological evidence supporting the hypothesis that fluid displacement, generated by sound or vibration, deflects the short stiff hair bundles of type I receptors at the striola, resulting in neural activation of the irregular afferents innervating them. So these afferents are activated by sound or vibration and show phase-locking to individual cycles of the sound or vibration stimulus up to frequencies above 2000 Hz, underpinning the use of sound and vibration for clinical tests of vestibular function.

Acute Unilateral Vestibulopathy

Normal vestibular end organs generate an equal resting-firing frequency of the axons, which is the same on both sides under static conditions. An acute unilateral vestibulopathy leads to a vestibular tone imbalance. Acute unilateral vestibulopathy is defined by the patient history and the clinical examination and, in unclear cases, laboratory examinations. Key signs and symptoms are an acute onset of spinning vertigo, postural imbalance and nausea as well as a horizontal rotatory nystagmus beating towards the non-affected side, a pathological head-impulse test and no evidence for central vestibular or ocular motor dysfunction. The so-called big five allow a differentiation between a peripheral and central lesion by the bedside examination. The differential diagnosis of peripheral labyrinthine and vestibular nerve disorders mimicking acute unilateral vestibulopathy includes central vestibular disorders, in particular "vestibular pseudoneuritis" and other peripheral vestibular disorders, such as beginning Menière's disease. The management of acute unilateral vestibulopathy involves (1) symptomatic treatment with antivertiginous drugs, (2) causal treatment with corticosteroids, and (3) physical therapy.

It is 2015: What are the best diagnostic and treatment options for Ménière’s disease?

Ménière’s disease (MD) is a common cause of recurrent vertigo. Its pathophysiology is still unclear and controversial. The most common histological finding in postmortem temporal bone studies of patients is endolymphatic hydrops (EH). However, not all cases of hydrops are associated with MD and it may represent the end point of various etiologies. The diagnostic criteria for MD have undergone changes during the past few decades. A recent collaboration among specialty societies in United States, Europe and Japan has given rise to a new set of guidelines for the diagnosis and classification of MD. The aim is to develop international consensus criteria for MD that would help improve the quality of data collected from patients. The diagnosis of MD can be difficult in some cases as there is no gold standard for testing. Previous use of audiometric data and electrocochleography are poorly sensitive as screening tools. Recently magnetic resonance imaging as a diagnostic tool for identifying EH has gained popularity in Asia and Europe. Vestibular evoked myogenic potentials are also used but lack specificity. Finally, the treatment for MD has improved with the introduction of intratympanic treatments with steroids and gentamicin as well as less invasive treatment with the Meniett device.

Hippocampal gray matter volume in bilateral vestibular failure

Bilateral vestibular failure (BVF) is a severe chronic disorder of the labyrinth or the eighth cranial nerve characterized by unsteadiness of gait and disabling oscillopsia during head movements. According to animal data, vestibular input to the hippocampus is proposed to contribute to spatial memory and spatial navigation. Except for one seminal study showing the association of impaired spatial navigation and hippocampal atrophy, patient data in BVF are lacking. Therefore, we performed a voxel-wise comparison of the hippocampal gray matter volume (GMV) in a clinically representative sample of 27 patients with incomplete BVF and 29 age- and gender-matched healthy controls to test the hypothesis of hippocampal atrophy in BVF. Although the two groups did not generally differ in their hippocampal GMV, a reduction of GMV in the bilateral hippocampal CA3 region was significantly correlated with increased vestibulopathy-related clinical impairment. We propose that GMV reduction in the hippocampus of BVF patients is related to the severity of vestibular-induced disability which is in line with combined hippocampal atrophy and disorders of spatial navigation in complete vestibular deafferentation due to bilateral nerve section. Clinically, however, the most frequent etiologies of BVF cause incomplete lesions. Accordingly, hippocampus atrophy and deficits in spatial navigation occur possibly less frequently than previously suspected. Hum Brain Mapp 37:1998-2006, 2016. © 2016 Wiley Periodicals, Inc.

Ocular vestibular evoked myogenic potentials to vertex low frequency vibration as a diagnostic test for superior canal dehiscence

OBJECTIVE

To explore ocular vestibular evoked myogenic potentials (oVEMP) to low-frequency vertex vibration (125 Hz) as a diagnostic test for superior canal dehiscence (SCD) syndrome.

METHODS

The oVEMP using 125 Hz single cycle bone-conducted vertex vibration were tested in 15 patients with unilateral superior canal dehiscence (SCD) syndrome, 15 healthy controls and in 20 patients with unilateral vestibular loss due to vestibular neuritis. Amplitude, amplitude asymmetry ratio, latency and interaural latency difference were parameters of interest.

RESULTS

The oVEMP amplitude was significantly larger in SCD patients when affected sides (53 μVolts) were compared to non-affected (17.2 μVolts) or compared to healthy controls (13.6 μVolts). Amplitude larger than 33.8 μVolts separates effectively the SCD ears from the healthy ones with sensitivity of 87% and specificity of 93%. The other three parameters showed an overlap between affected SCD ears and non-affected as well as between SCD ears and those in the two control groups.

CONCLUSIONS

oVEMP amplitude distinguishes SCD ears from healthy ones using low-frequency vibration stimuli at vertex.

SIGNIFICANCE

Amplitude analysis of oVEMP evoked by low-frequency vertex bone vibration stimulation is an additional indicator of SCD syndrome and might serve for diagnosing SCD patients with coexistent conductive middle ear problems.

Vertigo and dizziness in children

Vertigo and dizziness of at least moderate severity occur in >5% of school-aged children and cause considerable restrictions in participation in school and leisure activity. More than 50% of dizzy children also have headache. Vestibular migraine and benign paroxysmal vertigo as a migraine precursor are the most common diagnoses in dizziness clinics for children and adolescents. They account for 30-60% of diagnoses. Other common causes are somatoform, orthostatic, or posttraumatic dizziness. All other disorders that are known to cause vertigo and dizziness in adults also occur in children, but incidence rates are usually lower. The vestibular and balance systems are largely developed after 1 year of age. Therefore, clinical and laboratory testing is reliable. Brain magnetic resonance imaging to exclude severe conditions, such as a brainstem tumor, is necessary only if clinical - in particular, ocular motor - testing is abnormal. Most conditions causing vertigo and dizziness in childhood and adolescence are treatable. Nonpharmacologic prophylaxis should always be recommended in vestibular migraine. Behavioral support is useful in somatization. Evidence for the effectiveness of drug therapy is largely based on experience in adult populations. High-quality controlled studies in childhood cohorts are sparse. It is important to make a correct diagnosis early on, as counseling and appropriate treatment may avoid chronic illness.

Bilateral vestibulopathy

The leading symptoms of bilateral vestibulopathy (BVP) are postural imbalance and unsteadiness of gait that worsens in darkness and on uneven ground. There are typically no symptoms while sitting or lying under static conditions. A minority of patients also have movement-induced oscillopsia, in particular while walking. The diagnosis of BVP is based on a bilaterally reduced or absent function of the vestibulo-ocular reflex (VOR). This deficit is diagnosed for the high-frequency range of the angular VOR by a bilaterally pathologic bedside head impulse test (HIT) and for the low-frequency range by a bilaterally reduced or absent caloric response. If the results of the bedside HIT are unclear, angular VOR function should be quantified by a video-oculography system (vHIT). An additional test supporting the diagnosis is dynamic visual acuity. Cervical and ocular vestibular-evoked myogenic potentials (c/oVEMP) may also be reduced or absent, indicating impaired otolith function. There are different subtypes of BVP depending on the affected anatomic structure and frequency range of the VOR deficit: impaired canal function in the low- and/or high-frequency VOR range only and/or otolith function only; the latter is very rare. The etiology of BVP remains unclear in more than 50% of patients: in these cases neurodegeneration is assumed. Frequent known causes are ototoxicity mainly due to gentamicin, bilateral Menière's disease, autoimmune diseases, meningitis and bilateral vestibular schwannoma, as well as an association with cerebellar degeneration (cerebellar ataxia, neuropathy, vestibular areflexia syndrome=CANVAS). In general, in the long term there is no improvement of vestibular function. There are four treatment options: first, detailed patient counseling to explain the cause, etiology, and consequences, as well as the course of the disease; second, daily vestibular exercises and balance training; third, if possible, treatment of the underlying cause, as in bilateral Menière's disease, meningitis, or autoimmune diseases; fourth, if possible, prevention, i.e., being very restrictive with the use of ototoxic substances, such as aminoglycosides. In the future vestibular implants may also be an option.

Vestibulo-spinal and vestibulo-ocular reflexes are modulated when standing with increased postural threat

We investigated how vestibulo-spinal reflexes (VSRs) and vestibulo-ocular reflexes (VORs) measured through vestibular evoked myogenic potentials (VEMPs) and video head impulse test (vHIT) outcomes, respectively, are modulated during standing under conditions of increased postural threat. Twenty-five healthy young adults stood quietly at low (0.8 m from the ground) and high (3.2 m) surface height conditions in two experiments. For the first experiment (n = 25) VEMPs were recorded with surface EMG from inferior oblique (IO), sternocleidomastoid (SCM), trapezius (TRP), and soleus (SOL) muscles in response to 256 air-conducted short tone bursts (125 dB SPL, 500 Hz, 4 ms) delivered via headphones. A subset of subjects (n = 19) also received horizontal and vertical head thrusts (∼150°/s) at each height in a separate session, comparing eye and head velocities by using a vHIT system for calculating the functional VOR gains. VEMP amplitudes (IO, TRP, SOL) and horizontal and vertical vHIT gains all increased with high surface height conditions (P < 0.05). Changes in IO and SCM VEMP amplitudes as well as horizontal vHIT gains were correlated with changes in electrodermal activity (ρ = 0.44-0.59, P < 0.05). VEMP amplitude for the IO also positively correlated with fear (ρ = 0.43, P = 0.03). Threat-induced anxiety, fear, and arousal have significant effects on VSR and VOR gains that can be observed in both physiological and functional outcome measures. These findings provide support for a potential central modulation of the vestibular nucleus complex through excitatory inputs from neural centers involved in processing fear, anxiety, arousal, and vigilance.

Subclinical vestibular dysfunction in migraine patients: a preliminary study of ocular and rectified cervical vestibular evoked myogenic potentials

Background

Many studies have identified various vestibular symptoms and laboratory abnormalities in migraineurs. Although the vestibular tests may be abnormal, the changes may exist without vestibular symptoms. To date, vestibular-evoked myogenic potential (VEMP) has been the easiest and simplest test for measuring vestibular function in clinical practice. Cervical VEMP (cVEMP) represents a vestibulo-collic reflex, whereas ocular VEMP (oVEMP) reflects a vestibulo-ocular pathway. Therefore, we determined whether ocular and rectified cervical VEMPs differed in patients with migraine or tension type headache (TTH) and compared the results to controls with no accompanying vestibular symptoms.

Methods

The present study included 38 females with migraine without aura, 30 with episodic TTH, and 50 healthy controls without vestibular symptoms. oVEMP and cVEMP using a blood pressure manometer were recorded during a headache-free period. From the VEMP graphs, latency and amplitude parameters were analyzed, especially following EMG rectification in cVEMP.

Results

With respect to oVEMP, the migraine group exhibited significantly longer mean latencies of bilateral n1 and left p1 than the other groups (p < 0.05). Amplitudes of n1-p1 were lower than in other groups, but the difference did not reach statistical significance. In regards to cVEMP, p13 and n23 latencies and amplitudes after rectification did not differ significantly among groups.

Conclusions

An abnormal interictal oVEMP profile was associated with subclinical vestibular dysfunction in migraineurs, suggesting pathology within the vestibulo-ocular reflex. oVEMP is a more reliable measure than cVEMP to evaluate vestibular function in migraineurs, although results from the two tests in patients with migraine are complementary.

Deconvolution of the vestibular evoked myogenic potential using the power spectrum of the electromyogram

BACKGROUND

The vestibular evoked myogenic potential (VEMP) can be modelled reasonably well by convolving two functions: one representing an average motor unit action potential (MUAP), the other representing the temporal modulation of the MUAP rate (rate modulation). It is the latter which contains the information of interest, and so it would be desirable to be able to estimate this function from a combination of the VEMP with some other data. As the VEMP is simply a stimulus-triggered average of the electromyogram (EMG), a supplementary, easily accessible source of information is the EMG power spectrum, which can be shown to be roughly proportional to the squared modulus of the Fourier transform of the MUAP. But no phase information is available for the MUAP so that a straightforward deconvolution is not possible.

METHODS

To get around the problem of incomplete information, the rate modulation is described by a thoughtfully chosen function with just a few adjustable parameters. The convolution model is then used to make predictions as to the energy spectral density of the VEMP, and the parameters are optimized using a cost function that quantifies the difference between model prediction and data.

RESULTS

The workability of the proposed approach is demonstrated by analysing Monte Carlo simulated data and exemplary data from patients who underwent VEMP testing as part of a clinical evaluation of their dizziness symptoms.

CONCLUSIONS

The approach is suited, for example, to estimate the duration of the inhibition causing the VEMP or to disentangle a VEMP consisting of more than one component.

The sensory-motor theory of rhythm and beat induction 20 years on: a new synthesis and future perspectives

Some 20 years ago Todd and colleagues proposed that rhythm perception is mediated by the conjunction of a sensory representation of the auditory input and a motor representation of the body (Todd, 1994a, 1995), and that a sense of motion from sound is mediated by the vestibular system (Todd, 1992a, 1993b). These ideas were developed into a sensory-motor theory of rhythm and beat induction (Todd et al., 1999). A neurological substrate was proposed which might form the biological basis of the theory (Todd et al., 2002). The theory was implemented as a computational model and a number of experiments conducted to test it. In the following time there have been several key developments. One is the demonstration that the vestibular system is primal to rhythm perception, and in related work several experiments have provided further evidence that rhythm perception is body dependent. Another is independent advances in imaging, which have revealed the brain areas associated with both vestibular processing and rhythm perception. A third is the finding that vestibular receptors contribute to auditory evoked potentials (Todd et al., 2014a,b). These behavioral and neurobiological developments demand a theoretical overview which could provide a new synthesis over the domain of rhythm perception. In this paper we suggest four propositions as the basis for such a synthesis. (1) Rhythm perception is a form of vestibular perception; (2) Rhythm perception evokes both external and internal guidance of somatotopic representations; (3) A link from the limbic system to the internal guidance pathway mediates the “dance habit”; (4) The vestibular reward mechanism is innate. The new synthesis provides an explanation for a number of phenomena not often considered by rhythm researchers. We discuss these along with possible computational implementations and alternative models and propose a number of new directions for future research.

Cervical and ocular vestibular evoked myogenic potentials in Behcet's disease

OBJECTIVE

To investigate vestibular evoked myogenic potentials combined with audiologic status in Behcet's disease (BD) and to compare the results with normal healthy subjects.

METHODS

Cervical vestibular evoked myogenic potential (cVEMP) test, ocular vestibular evoked myogenic potential (oVEMP) test, Dix-Hallpike test, conventional pure tone audiometry (cPTA) and high frequency audiometry (HFA), and 226 and 1000Hz tympanometry were performed to each subject of the study. Cranial magnetic resonance imaging (MRI) with contrast enhancement was also performed to evaluate the central nervous system (CNS) in patients with BD.

RESULTS

VEMP parameters including the mean peak latencies of p13-n23 and n10-p15, AR values and thresholds were not statistically different both in cVEMP and oVEMP between the BD and control groups. Except for 250Hz, mean audiological thresholds were significantly higher in the BD group. Five of the 20 patients had pathological cranial MRI findings that may be compatible with central nervous system involvement.

CONCLUSION

To our knowledge, the present study is the first report investigating oVEMP and cVEMP responses combined with MRI findings in patients with BD. The presence of high frequency hearing loss is a common finding in BD and HFA may help early detection of hearing loss in patients with BD when combined with cPTA.