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.

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.

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.

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.

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.

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.

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.

Skull tap induced vestibular evoked myogenic potentials: an ipsilateral vibration response and a bilateral head acceleration response?

OBJECTIVE: To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP). METHODS: An electro-mechanical "skull tapper" (that provided a constant stimulus intensity) was used to test the effects of different midline stimulus sites/directions in healthy subjects (n=10) and in patients with severe unilateral loss of vestibular function (n=8). RESULTS: The standardized midline skull taps caused highly reproducible VEMP. There were highly significant differences in amplitude and latency in both normals and patients depending on site/direction of tapping (suggesting a stimulus direction dependency). Occiput skull taps caused, in comparisons to forehead and vertex taps, larger amplitude VEMP with more pronounced differences between the lesioned and the healthy side in the patients. CONCLUSIONS: The present data, in conjunction with earlier findings, support a theory that skull tap VEMP are mediated by two different mechanisms. It is suggested that skull tapping causes both skull vibration and head acceleration. Further, the VEMP would be the sum of the direction-independent vibration-induced response (from the sound-sensitive part of the saccule) and the direction-dependent head acceleration response (from other parts of the labyrinth). SIGNIFICANCE: Skull tap VEMP, as a diagnostic test, is not equivalent to sound-induced VEMP.

[Should vestibular neuritis be treated with corticosteroids?]. / Bør vestibularisnevritt behandles med kortikosteroider?

Recent studies have shown that corticosteroid treatment of patients with vestibular neuritis significantly improves recovery of peripheral vestibular function. At follow-up, the number of patients with a normal caloric response was larger among those treated with corticosteroids. However, improvement of caloric responses may not correlate directly with patient symptoms and up to now improved vertigo/dizziness due to corticosteroid treatment has not been reported. Consequently, although corticosteroid may be a treatment option, it should currently only be considered in those vestibular neuritis patients who are willing to take part in a structured follow-up with both caloric testing and evaluation of subjective symptoms.

Age-related changes in vestibular evoked myogenic potentials.

Vestibular evoked myogenic potentials (VEMP) in response to sound stimulation (500 Hz tone burst, 129 dB SPL) were studied in 1000 consecutive patients. VEMP from the ear with the larger amplitude were evaluated based on the assumption that the majority of the tested patients probably had normal vestibular function in that ear. Patients with known bilateral conductive hearing loss, with known bilateral vestibular disease and those with Tullio phenomenon were not included in the evaluation. It was found that there was an age-related decrease in VEMP amplitude and an increase in VEMP latency that appeared to be rather constant throughout the whole age span. The VEMP data were also compared to an additional group of 10 patients with Tullio phenomenon. Although these 10 patients did have rather large VEMP, equally large VEMP amplitudes were observed in a proportion of unaffected subjects of a similar age group. Thus, the finding of a large VEMP amplitude in response to a high-intensity sound stimulation is not, per se, distinctive for a significant vestibular hypersensitivity to sounds.

Preserved vestibular evoked myogenic potentials (VEMP) in some patients with walking-induced oscillopsia due to bilateral vestibulopathy.

Bilateral vestibulopathy, i.e. decreased peripheral vestibular function affecting both ears, is characterized by unsteadiness of gait, particularly in darkness and by motion-induced oscillopsia. We have recently seen a few patients with severely impaired semicircular canal function albeit with rather normal vestibular evoked myogenic potentials (VEMP) suggesting normal saccular function. The five young patients, mean age 27 years (range 15-45), 4 males and 1 female, had severely impaired balance in darkness and they all reported walking-induced vertical oscillopsia. Hence, these patients with incomplete vestibular lesions had symptoms that were indistinguishable from the typical patient with bilateral vestibulopathy. Further, the findings in these patients suggest that saccular function probably contributes little to prevent walking-induced vertical oscillopsia.

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.

Posterior canal dehiscence syndrome caused by an apex cholesteatoma.

OBJECTIVE: To compare audio-vestibular findings caused by a dehiscence of the posterior semicircular canal with those found in the superior canal dehiscence syndrome. STUDY DESIGN: Case report. SETTING: University hospital, tertiary referral center. PATIENT: The 44-year-old woman suffered from a gradual hearing loss with pulse-synchronous tinnitus as well as sound and pressure-induced vertigo. INTERVENTION: Audio-vestibular testing and high-resolution computed tomography. MAIN OUTCOME MEASURE: The superior canal dehiscence syndrome is caused by failure of normal postnatal bone development in the middle cranial fossa leading to absence of bone at the most superior part of the superior semicircular canal. The typical features for this syndrome are sound- and pressure-induced vertigo with torsional eye movements, pulse synchronous tinnitus and apparent conductive hearing loss in spite of normal middle-ear function. We present a patient with very similar symptoms and findings who, instead, had a posterior semicircular canal dehiscence caused by an apex cholesteatoma. CONCLUSION: Patients with semicircular canal dehiscence have common auditory-vestibular features regardless of which of the two vertical semicircular canals is affected. The only obvious difference between the two is the vertical component of the sound and pressure-induced eye movements (which beats in opposite directions).

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.

Migraine-associated vertigo.

CONCLUSIONS: It is probably not wise to demand a temporal relationship between migraine symptoms and vertigo for the definition of migrainous vertigo. When recurrent vertigo attacks begin at an early age in a patient with normal hearing and migraine, there are few diagnoses other than migraine that need to be considered. OBJECTIVE: The clinical association between migraine and vestibular symptoms, such as dizziness, motion intolerance and spontaneous attacks of vertigo, is well documented. Recently, investigators have attempted to develop diagnostic criteria for this association. We hypothesized that there are multiple migraine-associated vestibular syndromes and studied a more homogenous subset of them (benign recurrent vertigo). MATERIAL AND METHODS: A structured interview was conducted over the telephone with 40 patients who presented to our neurotology clinic with benign recurrent vertigo and met the International Headache Society criteria for migraine. The structured interview was also conducted with 40 relatives of the patients who reported the same symptoms. RESULTS: A marked female predominance was found. Most of the patients had vertigo attacks lasting minutes or hours and most were completely free of dizziness between attacks. Imbalance and nausea typically accompanied the vertigo. However, in half of the cases, vertigo occurred without an association with headache.

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.

Subarcuate venous malformation causing audio-vestibular symptoms similar to those in superior canal dehiscence syndrome.

OBJECTIVE: To present a patient with symptoms similar to those of superior canal dehiscence syndrome due to another cause. STUDY DESIGN: Case report. SETTING: University hospital, tertiary referral center. PATIENT: The 65-year-old woman had suffered for 4 years from hearing loss, tinnitus, and pressure-induced vertigo. INTERVENTION: Audio-vestibular testing, high-resolution computed tomography, and magnetic resonance angiography. MAIN OUTCOME MEASURE: The superior canal dehiscence syndrome is caused by failure of normal postnatal bone development in the middle cranial fossa leading to absence of bone at the most superior part of the superior semicircular canal. The typical features for this syndrome are sound and pressure-induced vertigo with torsional eye movements, pulse synchronous tinnitus and apparent conductive hearing loss in spite of normal middle ear function. We present a patient with very similar symptoms and findings, who instead had a superior canal dehiscence close to the common crus. Neuroradiologic findings suggested that the dehiscence was related to a venous malformation. CONCLUSIONS: Symptoms and findings suggesting superior canal dehiscence syndrome can have a different cause.

Familial early-onset progressive vestibulopathy without hearing impairment.

A family with early-onset vestibulopathy is presented. The 34-year-old father had experienced brief attacks of vertigo and currently suffers from unsteadiness and oscillopsia during head movements. His two young sons also experience brief attacks of spontaneous vertigo. In vestibular testing all three subjects showed reduced caloric responses. However, only the father showed reduced otolith function (as reflected by the vestibular-evoked myogenic potentials). Further, all three subjects had walked before the age of 1 year and none of them had had any auditory symptoms. It is suggested that they have familial early-onset progressive vestibulopathy affecting the canals before the otoliths but sparing cochlear function.