[Show abstract][Hide abstract] ABSTRACT: 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.
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.
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.
Although the entire elephant's skull was otherwise broadly aerated, the labyrinth areas were surrounded by dense bone.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Objective
To investigate low-frequency vertex bone-conducted (BC) vibration for evoking ocular vestibular myogenic potentials (oVEMPs) and its ability to discriminate between lesioned and healthy ears.
oVEMPs were analysed in response to 125-Hz single cycle vertex BC vibration in healthy subjects (n=50) and in patients with severe unilateral vestibular loss (n=10). Both positive and negative initial stimulus motions were used.
In most healthy subjects, vertex BC vibration oVEMPs was successfully and symmetrically evoked from both ears. The response was dependent on the direction of the stimulus motion. The latency was shorter with negative initial stimulus motion; however, a positive initial stimulus motion generated somewhat larger amplitudes. Furthermore, there was no significant response from lesioned ears, whereas oVEMPs from the patients’ healthy ears were similar to the responses in healthy subjects.
The oVEMP low-frequency BC response was dependent on the direction of the initial stimulus motion. Testing oVEMPs in response to low-frequency vertex vibration can discriminate patients with unilateral vestibular function loss from healthy controls.
Low-frequency vertex BC vibration oVEMPs should be considered a possible clinical screening test to evaluate vestibular function.
[Show abstract][Hide abstract] ABSTRACT: 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.
Experimental Brain Research 01/2014; 232(4). DOI:10.1007/s00221-013-3782-z · 2.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To explore the stimulus site and stimulus configuration dependency for bone-conducted low-frequency vibration-induced ocular vestibular evoked myogenic potentials (oVEMPs).
oVEMPs were tested in response to 125Hz 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.
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.
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.
Low-frequency bone vibration stimulation at vertex might serve for simultaneous oVEMP testing of both ears.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 09/2013; 125(3). DOI:10.1016/j.clinph.2013.08.019 · 2.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
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.
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.
Aviation Space and Environmental Medicine 11/2012; 83(11):1097-100. DOI:10.3357/ASEM.3284.2012 · 0.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract 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.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: 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.
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.
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.
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.
[Show abstract][Hide abstract] ABSTRACT: To explore the mechanisms for skull tap induced ocular vestibular evoked myogenic potentials (oVEMP).
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).
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.
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.
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.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 02/2011; 122(2):391-7. DOI:10.1016/j.clinph.2010.06.020 · 2.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Seminars in Neurology 11/2009; 29(5):541-7. DOI:10.1055/s-0029-1241042 · 1.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of neurology, neurosurgery, and psychiatry 09/2009; 81(4):451-5. DOI:10.1136/jnnp.2009.173732 · 5.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP).
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).
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.
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).
Skull-tap VEMP probably have two different mechanisms. Separation of the two components might reveal the status of different labyrinthine functions.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 05/2009; 120(5):974-9. DOI:10.1016/j.clinph.2009.03.008 · 2.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Tidsskrift for den Norske laegeforening 10/2008; 128(18):2062-3.
[Show abstract][Hide abstract] ABSTRACT: To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP).
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).
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.
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).
Skull tap VEMP, as a diagnostic test, is not equivalent to sound-induced VEMP.
[Show abstract][Hide abstract] ABSTRACT: 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.
Audiology and Neurotology 09/2008; 14(1):54-8. DOI:10.1159/000153435 · 1.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Audiology and Neurotology 06/2007; 12(4):247-53. DOI:10.1159/000101332 · 1.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Vestibular Research 02/2007; 17(1):33-8. · 1.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To compare audio-vestibular findings caused by a dehiscence of the posterior semicircular canal with those found in the superior canal dehiscence syndrome.
University hospital, tertiary referral center.
The 44-year-old woman suffered from a gradual hearing loss with pulse-synchronous tinnitus as well as sound and pressure-induced vertigo.
Audio-vestibular testing and high-resolution computed tomography.
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.
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).
[Show abstract][Hide abstract] ABSTRACT: Two patients with unprovoked drop attacks were found to have dehiscence of the superior semicircular canal on CT of the temporal bone. Both had conductive hearing loss, preservation of stapedius reflex, and abnormal vestibular evoked myogenic potentials. Neither had sound- or pressure-induced nystagmus. Repair of the dehiscence in one case stopped the drop attacks, supporting a causal relationship between the dehiscence and the drop attacks.