Methodological aspects of testing vestibular evoked myogenic potentials in infants at universal hearing screening program.

Motor development in infants is dependent upon the function of the inner ear balance organ (vestibular organ). Vestibular failure causes motor delays in early infancy and suboptimal motor skills later on. A vestibular test for newborns and infants that is applicable on a large scale, safe and cost effective is in demand in various contexts: in the differential diagnosis of early onset hearing loss to determine forms associated with vestibular failure; in early hearing habilitation with cochlear implant, indicating the vestibular predominant side; and in the habilitation of children affected by motor skill disorders, revealing the contribution of a vestibular failure. This work explored the feasibility of cervical vestibular evoked myogenic potentials (VEMP) in conjunction with newborn universal hearing screening program. VEMP was measured after the hearing tests and was evoked by bone-conducted stimuli. Moreover, stimulus delivery was regulated by neck muscle activity, with infants rested unconstrained in their parents´ arms and with the head supported by the operator´s hand. This VEMP protocol showed a high level of feasibility in terms of test viability and result reproducibility. VEMP integrated into the newborn hearing screening program may represent a practical method for large-scale assessment of balance function in infants.

Diagnostic Accuracy of Ocular Vestibular Evoked Myogenic Potentials for Superior Canal Dehiscence Syndrome in a Large Cohort of Dizzy Patients.

OBJECTIVES: To determine the diagnostic accuracy of ocular vestibular evoked myogenic potentials (oVEMPs) for superior canal dehiscence syndrome (SCDS) in a large cohort of unselected dizzy patients. Most SCDS patients are dizzy (90%); however, only 30% demonstrate archetypical SCDS clinical proxies (Tullio or Hennebert findings). Several case-control studies have addressed specific SCDS markers using VEMP testing, but the diagnostic value of VEMP for SCDS has not been demonstrated in a target population of dizzy patients. The aim of this study was to confirm the diagnostic properties of oVEMP for SCDS in an unselected cohort of dizzy patients. DESIGN: This diagnostic accuracy study was performed in a tertiary referral center and included a consecutive sample of dizzy patients referred for vestibular function testing. One hundred fifty subjects were collected prospectively; five were excluded due to middle ear disorders, 10 had the target condition (SCDS group), and 135 had an alternative condition (non-SCDS group), based on diagnostic criteria for SCDS used in our department as reference standard. The non-SCDS group was subdivided into diagnostic categories including an "undefined dizziness" group. The index test applied to the total sample (missing data: 1%) consisted of oVEMP recording using three different stimulation modalities, that is, air-conducted (AC) sound stimulation and midsagittal bone-conducted (BC) vibration at both forehead (Fz) and vertex (Cz). Data analysis was conducted on four oVEMP parameters: amplitude, latency, amplitude asymmetry ratio, and interaural latency difference. Between-group analysis was conducted with nonparametric tests. The oVEMP diagnostic accuracy for SCDS was determined with uni/multiparametric receiver operating characteristic analysis. Best cutoff points were computed for those parameters or parameter combinations that showed an accuracy level appropriate for clinical use (area under the curve [AUC] > 0.8). RESULTS: Different oVEMP parameters, in particular, the amplitude to AC stimulation (SCDS: 53, inter quartile range [IQR]: 27.6-68.3 µV; non-SCDS: 4.4, IQR: 2.0-8.1 µV; p < 0.001), were able to separate SCDS from non-SCDS conditions with statistical significance. AC oVEMP amplitude had the highest diagnostic accuracy (area under the curve = 0.96) for SCDS, with optimal sensitivity (100%) and high specificity (89%) at a specific cutoff point (16.7 µV); as an SCDS index, it could distinguish these patients not only from those with other vestibular diagnoses but also from patients with undefined dizziness (sensitivity 100%; specificity 81%). CONCLUSIONS: oVEMP was able to identify all subjects affected by SCDS, according to our diagnostic criteria, in a large cohort of unselected dizzy patients. The AC oVEMP amplitude parameter showed optimal sensitivity and high specificity for SCDS and may represent an ideal screening test for SCDS among dizzy patients. This is noteworthy when considering that not all SCDS patients express the clinical key features of vestibular hypersensitivity to sound or pressure change, even though most complain of dizziness.

Practice guideline: Cervical and ocular vestibular evoked myogenic potential testing: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology.

OBJECTIVE: To systematically review the evidence and make recommendations with regard to diagnostic utility of cervical and ocular vestibular evoked myogenic potentials (cVEMP and oVEMP, respectively). Four questions were asked: Does cVEMP accurately identify superior canal dehiscence syndrome (SCDS)? Does oVEMP accurately identify SCDS? For suspected vestibular symptoms, does cVEMP/oVEMP accurately identify vestibular dysfunction related to the saccule/utricle? For vestibular symptoms, does cVEMP/oVEMP accurately and substantively aid diagnosis of any specific vestibular disorder besides SCDS? METHODS: The guideline panel identified and classified relevant published studies (January 1980-December 2016) according to the 2004 American Academy of Neurology process. RESULTS AND RECOMMENDATIONS: Level C positive: Clinicians may use cVEMP stimulus threshold values to distinguish SCDS from controls (2 Class III studies) (sensitivity 86%-91%, specificity 90%-96%). Corrected cVEMP amplitude may be used to distinguish SCDS from controls (2 Class III studies) (sensitivity 100%, specificity 93%). Clinicians may use oVEMP amplitude to distinguish SCDS from normal controls (3 Class III studies) (sensitivity 77%-100%, specificity 98%-100%). oVEMP threshold may be used to aid in distinguishing SCDS from controls (3 Class III studies) (sensitivity 70%-100%, specificity 77%-100%). Level U: Evidence is insufficient to determine whether cVEMP and oVEMP can accurately identify vestibular function specifically related to the saccule/utricle, or whether cVEMP or oVEMP is useful in diagnosing vestibular neuritis or Ménière disease. Level C negative: It has not been demonstrated that cVEMP substantively aids in diagnosing benign paroxysmal positional vertigo, or that cVEMP or oVEMP aids in diagnosing/managing vestibular migraine.

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.

Enhanced Auditory Sensitivity to Body Vibrations in Superior Canal Dehiscence Syndrome.

A key feature of superior canal dehiscence (SCD) syndrome is supranormal hearing of body sounds. The aim of the present study was to quantify this phenomenon and to ascertain whether auditory sensitivity to body vibrations can distinguish SCD patients. Hearing thresholds in response to vibration at the vertex, at the spinous process of the 7th cervical vertebra, and at the medial malleolus were tested in 10 SCD patients and 10 controls. Both patients and controls had insert earphones in both ears. The insert in the test ear was blocked while masking was presented to the other ear. Vibration in the frequency range of 125-1,000 Hz was presented to each of the 3 stimulation sites. The SCD patients were found to have significantly lower hearing thresholds compared with controls. The two study groups reacted differently with respect to frequency. The SCD patients showed an enhanced sensitivity for the lower stimulus frequencies. The difference was, however, rather independent of stimulus presentation site. The findings suggest that hearing thresholds in response to low-frequency body vibration at sites distant from the ears can distinguish SCD patients. The present findings may also support the idea that auditory sensation to body vibrations is a response related to soft tissue conduction.

Do extant elephants have superior canal dehiscence syndrome?

CONCLUSION: X-ray CT of an Asian elephant's skull suggest that elephants do not have a labyrinthine 3(rd) mobile window. This excludes the concept that elephants benefit from enhancement of bone conducted vibration by an extra opening of the labyrinth. This finding does not, however, exclude that elephants use bone conducted hearing for seismic detection, nor that other species may use an extra labyrinthine opening for improved detection of seismic signals. OBJECTIVES: In man, a pathologic extra opening of the bony labyrinth causes altered hearing with supranormal bone conduction. Theoretically, this variation in auditory performance could be advantageous for detection of seismic waves. METHOD: The skull of an adult Asian elephant was examined by X-ray computed tomography to investigate whether a natural '3(rd) mobile window' mechanism for enhanced sensitivity of body sounds exist in elephants. RESULTS: Although the entire elephant's skull was otherwise broadly aerated, the labyrinth areas were surrounded by dense bone.

Microvascular decompression for typewriter tinnitus-case report.

BACKGROUND: Microvascular decompression has been tested as a treatment for tinnitus. METHODS: However, only a fraction of patients appear to benefit from surgery if the combination of findings such as paroxysmal vertigo, ABR changes and tinnitus is used to select patients for microvascular decompression. RESULTS: Instead, a more specific syndrome of staccato or "typewriter" tinnitus, which is highly responsive to carbamazepine, was suggested to be caused by a neurovascular conflict. CONCLUSION: We present the first case of typewriter tinnitus with complete long-term symptom relief following microvascular decompression of the vestibulocochlear nerve. We suggest that this specific syndrome is caused by a neurovascular conflict and treatable by microvascular decompression.

Ocular vestibular-evoked myogenic potentials (oVEMP) to skull taps in normal and dehiscent ears: mechanisms and markers of superior canal dehiscence.

The site of stimulus delivery modulates the waveforms of cervical- and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP) to skull taps in healthy controls. We examine the influence of stimulus location on the oVEMP waveforms of 18 patients (24 ears) with superior canal dehiscence (SCD) and compare these with the results of 16 healthy control subjects (32 ears). oVEMPs were recorded in response to taps delivered with a triggered tendon-hammer and a hand-held minishaker at three midline locations; the hairline (Fz), vertex (Cz) and occiput (Oz). In controls, Fz stimulation evoked a consistent oVEMP waveform with a negative peak (n1) at 9.5 ± 0.5 ms. In SCD, stimulation at Fz produced large oVEMP waveforms with delayed n1 peaks (tendon-hammer = 13.2 ± 1.0 ms and minitap = 11.5 ± 1.1 ms). Vertex taps produced diverse low-amplitude waveforms in controls with n1 peaks at 15.5 ± 1.2 and 13.2 ± 1.3 ms for tendon-hammer taps and minitaps, respectively; in SCD, they produced large amplitude oVEMP waveforms with n1 peaks at 12.9 ± 0.8 ms (tendon-hammer) and 12.1 ± 0.5 ms (minitap). Occiput stimulation evoked oVEMPs with similar n1 latencies in both groups (tendon-hammer = 11.3 ± 1.3 and 10.7 ± 0.8; minitap = 10.3 ± 0.9 and 11.1 ± 0.4 for control and SCD ears, respectively). Compared to reflex amplitudes, n1 peak latencies to Fz taps provided clearer separation between SCD and control ears. The distinctly different effects of Fz and vertex taps on the oVEMP waveforms may represent an additional non-osseous mechanism of stimulus transmission in SCD. For skull taps at Fz, a prolonged n1 latency is an indicator of SCD.

Mastoid and vertex low-frequency vibration-induced oVEMP in relation to medially directed acceleration of the labyrinth.

OBJECTIVE: To explore the stimulus site and stimulus configuration dependency for bone-conducted low-frequency vibration-induced ocular vestibular evoked myogenic potentials (oVEMPs). METHODS: oVEMPs were tested in response to 125 Hz single cycle bone-conducted vibration in healthy subjects (n=12) and in patients with severe unilateral vestibular lesions (n=10). The stimulus sites were the mastoids and vertex. Both directions of initial stimulus motion were used. RESULTS: At mastoid stimulation, the oVEMP to initial laterally directed acceleration of the labyrinth was delayed approximately the length of time of a stimulus half-cycle, as compared with the response to initial medially directed acceleration. At vertex stimulation, the oVEMP to positive initial acceleration was similar to the oVEMP to mastoid stimulation causing lateral initial acceleration. Likewise, the oVEMP to vertex negative initial acceleration was similar to mastoid stimulation causing initial medial acceleration. Further, patients with unilateral vestibular loss had, compared to healthy subjects, similar oVEMP from the healthy labyrinth. CONCLUSIONS: A fundamental dependency on medially directed accelerations of the labyrinth, based on the latency differences revealed, may theoretically account for oVEMP in response to low-frequency stimulation. SIGNIFICANCE: Low-frequency bone vibration stimulation at vertex might serve for simultaneous oVEMP testing of both ears.

Superior vestibular dysfunction in severe decompression sickness suggests an embolic mechanism.

BACKGROUND: Both nitrogen bubble embolism and the difficulty of inner ear tissues to wash out nitrogen have been discussed as possible reasons for the selective vulnerability of the inner ear to decompression illness. This case report suggests that nitrogen bubble embolism plays a crucial role in the pathogenesis of inner ear lesions in decompression accidents. CASE REPORT: The current patient, a 48-yr-old male dive master, suffered a severe decompression illness with vertigo as the only residual symptom. At the 1-mo follow-up, neuro-otological evaluation revealed a selective lesion of the superior vestibular division of the left labyrinth with normal functioning inferior vestibular division. At vestibular testing, there was no caloric response from the affected left ear, and the head impulse tests for the lateral and anterior semicircular canal were also impaired. Tests of vestibular evoked myogenic potentials (VEMP) showed divergent results. Ocular VEMP in response to left ear stimulation were absent, whereas the cervical VEMP were completely symmetrical and normal. Thus, the lesion profile implies a partial vestibular loss selectively affecting the superior vestibular division of the inner ear. DISCUSSION: The most likely explanation for such a selective injury seems to be bubble microembolism coupled with both the specific anatomy of this terminally supplied subunit, and with the slow nitrogen wash-out of the vestibular organ.

Effectiveness of different click stimuli in diagnosing superior canal dehiscence using cervical vestibular evoked myogenic potentials.

CONCLUSION: Testing cervical vestibular evoked myogenic potential (cVEMP) in response to 90 dB nHL clicks can, in contrast to high-intensity 500 Hz tone bursts, be used as a screening test for superior canal dehiscence (SCD) syndrome. OBJECTIVES: cVEMP testing has its key clinical significance for evaluating saccular and inferior vestibular nerve function, but also for assessment of vestibular hypersensitivity to sounds in patients with SCD syndrome. The routine stimulus used in cVEMP testing is high-intensity 500 Hz tone bursts. The aim of the present study was to compare the high-intensity tone burst stimulation with less intense click stimulations for the diagnosis of SCD syndrome. METHODS: cVEMP amplitudes in response to 500 Hz tone bursts and clicks were studied in 38 patients with SCD syndrome unilaterally. RESULTS: cVEMP testing using high-intensity 500 Hz tone bursts did not consistently distinguish SCD patients. This nonfunctioning of high-intensity 500 Hz stimulation is most likely due to saturation. With 90 and 80 dB nHL clicks there is low risk for saturation and both these click stimulations were effective. Testing with both 80 and 90 dB nHL clicks did not have any significant advantage over just using 90 nHL dB clicks.

Ménière's disease in children aged 4-7 years.

This is a retrospective review of clinical data and audiovestibular test results from four children in whom symptoms suggesting Ménière's disease started at 4-7 years of age. The four patients all had spontaneous recurrent attacks of (spinning) vertigo and fluctuating low frequency sensorineural hearing loss from an early age, suggesting a diagnosis of definite Ménière's disease. Presumably, due to age-related inability to communicate auditory symptoms, the children did not initially meet requirements for a diagnosis of Ménière's disease. However, by 8 years of age, all four children reported tinnitus and/or fullness in the affected ear and, thus, met the AAO criteria for Ménière's disease. Even if information on subjective auditory symptoms is missing, it is reasonable to consider young children with idiopathic spontaneous recurrent attacks of vertigo in whom audiograms reveals fluctuating low frequency hearing loss to have Ménière's disease. This report is a reminder that Ménière's disease may also occur in young children.

Similarity of vertigo attacks due to Meniere's disease and benign recurrent vertigo, both with and without migraine.

CONCLUSION: Vertigo attacks in patients with benign recurrent vertigo (BRV) cannot be distinguished from those in patients with Meniere's disease on the basis of duration, triggers or associated symptoms (other than auditory). A subset of BRV is associated with migraine. OBJECTIVE: To investigate whether clinical features of vertigo attacks can distinguish patients with BRV from those with Meniere's disease and whether subtypes of BRV can be identified. METHODS: A structured interview was used to analyze features in patients with BRV, i.e. those who have normal audiograms and caloric test results even though they have had recurrent vertigo (n = 63). A group of patients with definite Meniere's disease (n = 112) served as the comparison group. RESULTS: Compared with the Meniere's disease group, patients with BRV had a female preponderance, earlier age of onset, and increased incidence of migraine headaches (IHS criteria). With regard to the vertigo attacks, duration tended to be shorter in patients with BRV but there was a large overlap in the duration of attacks between the two groups. Triggers (stress/emotional upset, fatigue, menstrual periods) and associated symptoms (imbalance, nausea and vomiting, headache, sensitivity to light) were not significantly different in the two groups.

Ocular vestibular evoked myogenic potentials: skull taps can cause a stimulus direction dependent double-peak.

OBJECTIVE: To explore the mechanisms for skull tap induced ocular vestibular evoked myogenic potentials (oVEMP). METHODS: An electro-mechanical "skull tapper" was used to test oVEMP in response to four different stimulus sites (forehead, occiput and above each ear) in healthy subjects (n=20) and in patients with unilateral loss of vestibular function (n=10). RESULTS: In normals, the oVEMP in response to forehead taps and the contra-lateral oVEMP to taps above the ears were similar. These responses had typical oVEMP features, i.e. a short-latency negative peak (n10) followed by a positive peak (p15). In contrast, the ipsi-lateral oVEMP to the laterally directed skull taps, as well as the oVEMP to occiput taps, had an initial double negative peak (n10+n10b). In patients with unilateral loss of vestibular function, the crossed responses from the functioning labyrinth were very similar to the corresponding oVEMP in normals. CONCLUSIONS: The present data support a theory that skull tapping may cause both a response that is more stimulus direction dependent and one that is less so. SIGNIFICANCE: Whereas the stimulus direction dependent occurrence of the negative double-peak might reveal the functional status of one part of the labyrinth, the rather stimulus direction-independent response might reveal the functional status of other parts.

Paroxysmal staccato tinnitus: a carbamazepine responsive hyperactivity dysfunction symptom of the eighth cranial nerve.

Hyperactive disorders related to neurovascular compression have been described for several cranial nerves of which trigeminal neuralgia and hemifacial spasm are the best known. The present report on four patients, in conjunction with previous reports, suggests that paroxysmal staccato tinnitus might be considered an auditory hyperactivity disorder of the eighth cranial nerve. The present patients reported attacks, usually lasting 10-20 s, of loud monaural tinnitus with a staccato character (eg, clattering or sounding like a machine gun). The attacks occurred very frequently, sometimes every minute. The attacks were spontaneous but they were also provoked by certain head positions or by exposure to loud sounds. Most of the patients did not reveal any significant eighth cranial nerve sensory loss and thus it is probably not advisable to rely on any specific test result for this diagnosis. Instead, it is suggested that a diagnosis of paroxysmal staccato tinnitus can be based on the history as the symptoms are both stereotypic and very specific. Furthermore, low doses of carbamazepine, although not effective for the general population of tinnitus patients, relieved the symptoms.

Vestibular evoked myogenic potentials (VEMPs): usefulness in clinical neurotology.

Testing vestibular evoked myogenic potentials (VEMPs) may be the most important new clinical test for evaluation of vestibular function developed during the past 100 years since the introduction of the caloric test. VEMPs are easily recordable and therefore suitable for everyday testing in clinical neurotology. VEMPs in response to air-conducted sound stimulation using surface electrodes over the sternocleidomastoid muscles reveal saccular function, inferior vestibular nerve function, and vestibulocollic connections. At present, VEMPs are of clinical importance for estimating the severity of peripheral vestibular damage due to different pathophysiologic processes such as Ménière's disease, vestibular neuritis, and vestibular schwannoma. VEMPs can also be used to document vestibular hypersensitivity to sounds (Tullio phenomenon). In addition, VEMP testing constitutes an electrophysiologic method that is able to detect subclinical lesions in central vestibular pathways in patients with multiple sclerosis. In the near future, testing ocular VEMPs (OVEMPs) in response to bone-conducted vibration may prove to be of clinical importance for the evaluation of utricular function.

Vestibular evoked myogenic potentials in response to lateral skull taps are dependent on two different mechanisms.

OBJECTIVE: To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP). METHODS: The muscular responses were recorded over both sternocleidomastoid (SCM) muscles using skin electrodes. A skull tapper which provided a constant stimulus intensity was used to test cervical vestibular evoked myogenic potentials (VEMP) in response to lateral skull taps in healthy subjects (n=10) and in patients with severe unilateral loss of vestibular function (n=10). RESULTS: Skull taps applied approximately 2 cm above the outer ear canal caused highly reproducible VEMP. There were differences in VEMP in both normals and patients depending on side of tapping. In normals, there was a positive-negative ("normal") VEMP on the side contra-lateral to the skull tapping, but no significant VEMP ipsi-laterally. In patients, skull taps above the lesioned ear caused a contra-lateral positive-negative VEMP (as it did in the normals), in addition there was an ipsi-lateral negative-positive ("inverted") VEMP. When skull taps were presented above the healthy ear there was only a small contra-lateral positive-negative VEMP but, similar to the normals, no VEMP ipsi-laterally. CONCLUSIONS: The present data, in conjunction with earlier findings, support a theory that skull-tap VEMP responses are mediated by two different mechanisms. It is suggested that skull tapping causes both a purely ipsi-lateral stimulus side independent SCM response and a bilateral and of opposite polarity SCM response that is stimulus side dependent. Possibly, the skull tap induced VEMP responses are the sum of a stimulation of two species of vestibular receptors, one excited by vibration (which is rather stimulus site independent) and one excited by translation (which is more stimulus site dependent). SIGNIFICANCE: Skull-tap VEMP probably have two different mechanisms. Separation of the two components might reveal the status of different labyrinthine functions.

Testing vestibular-evoked myogenic potentials with 90-dB clicks is effective in the diagnosis of superior canal dehiscence syndrome.

Vestibular-evoked myogenic potentials (VEMP) in response to 90-dB-nHL clicks were studied in 20 patients (22 ears) with superior canal dehiscence syndrome. Their amplitude was compared to the VEMP from the 'unaffected' ears of 113 patients using the same stimulus level. The 113 control subjects were those from a previous study on 1,000 patients who had had large VEMP amplitudes in response to 500-Hz 129-dB-SPL tone bursts, and, because of this, had been tested with 90-dB-nHL clicks (which are a much weaker sound stimulus than our routine 500-Hz tone burst). It was found that 90-dB-nHL clicks clearly distinguished patients with vestibular hypersensitivity to sounds. In patients, the VEMP amplitude was usually larger than the simultaneously recorded background electromyographic activity (i.e. 'corrected' amplitude >1), whereas this was not the case for the controls. Consequently, it is suggested that 90-dB-nHL clicks can be used to screen for vestibular hypersensitivity to sounds. This finding has clinical implications for patients with suspected Tullio phenomenon because the definitive VEMP test for this (i.e. estimation of VEMP threshold) is not only time-consuming, but there is also difficulty related to the low signal-to-noise ratio close to the threshold.