Bilateral Vestibular Dysfunction Research Articles

Vestibular-dependent spinal reflexes evoked by brief lateral accelerations of the heads of standing subjects

An impulsive acceleration stimulus, previously shown to activate vestibular afferents, was applied to the mastoid. Evoked EMG responses from the soleus muscles in healthy subjects (n = 10) and patients with bilateral vestibular dysfunction (n = 3) were recorded and compared with the effects of galvanic stimulation (GVS). Subjects were stimulated while having their eyes closed, head rotated, and while tonically activating their soleus muscles. Rectified EMG responses were recorded from the leg contralateral to the direction of head rotation. Responses were characterized by triphasic potentials that consisted of short-latency (SL), medium-latency (ML), and long-latency (LL) components beginning at (mean ± SD) 54.2 ± 4.8, 88.4 ± 4.7, and 121 ± 7.1 ms, respectively. Mean amplitudes for the optimum stimulus rise times were 9.05 ± 3.44% for the SL interval, 16.70 ± 4.41% for the ML interval, and 9.75 ± 4.89% for the LL interval compared with prestimulus values. Stimulus rise times of 14 and 20 ms evoked the largest ML amplitudes. GVS evoked biphasic responses (SL and ML) with similar latencies. Like GVS, the polarity of the initial interval was determined by the polarity of the stimulus and the evoked EMG response was attenuated when subjects were seated. There was no significant EMG response evoked when subjects were stimulated using 500-Hz vibration or in patients with bilateral vestibular dysfunction. Our study demonstrates that a brief lateral acceleration, likely to activate the utricle, can evoke spinal responses with properties similar to those previously shown for vestibular activation by GVS. The triphasic nature of the responses may allow the nervous system to respond differently to short compared with long-duration linear accelerations, consistent with their differing significance.

A new method to analyze the subjective visual vertical in patients with bilateral vestibular dysfunction

OBJECTIVE:The aim of this study was to assess the subjective visual vertical in patients with bilateral vestibular dysfunction and to propose a new method to analyze subjective visual vertical data in these patients.METHODS:Static subjective visual vertical tests were performed in 40 subjects split into two groups. Group A consisted of 20 healthy volunteers, and Group B consisted of 20 patients with bilateral vestibular dysfunction. Each patient performed six measurements of the subjective visual vertical test, and the mean values were calculated and analyzed.RESULTS:Analyses of the numerical values of subjective visual vertical deviations (the conventional method of analysis) showed that the mean deviation was 0.326±1.13° in Group A and 0.301±1.87° in Group B. However, by analyzing the absolute values of the subjective visual vertical (the new method of analysis proposed), the mean deviation became 1.35±0.48° in Group A and 2.152±0.93° in Group B. The difference in subjective visual vertical deviations between groups was statistically significant (p<0.05) only when the absolute values and the range of deviations were considered.CONCLUSION:An analysis of the absolute values of the subjective visual vertical more accurately reflected the visual vertical misperception in patients with bilateral vestibular dysfunction.

若年者のめまい症例の臨床的検討

A study was conducted on children and adolescents complaining of vertigo, dizziness and equilibrium disturbance who were examined at the Department of Otorhinolaryngology of Mie University Hospital from August, 2000 to July, 2010. Of the 673 patients who visited our vertigo clinic, 22 (3.3%) were 18 years of age or under. Their equilibrium and neurological status were examined. They consisted of 7 boys and 15 girls and their ages ranged from 5 to 18. Of the 22 patients, 9 had orthostatic dysregulation, 8 had peripheral vestibular disorders and 3 had benign paroxysmal vertigo of childhood. In the vestibular diseases of peripheral origin, there were Ménière's disease, bilateral vestibular dysfunction, vestibular neuritis and large vestibular aqueduct syndrome. Regarding the characteristics of vertigo, 8 (35%) complained of rotatory vertigo and 15 (65%) non-rotatory vertigo. Eight (36%) had some kind of hearing loss. The long term clinical course of a 5-year-old girl with Ménière's disease and the clinical course of 9-year-old girl with benign paroxysmal vertigo of childhood are explained in detail.

An equilibrium exercise performed by a physical therapist for a patient with intractable dysequilibrium

An equilibrium exercise performed by a physical therapist for a patient with intractable dysequilibriumA thirty-seven-year-old woman diagnosed as having progressive bilateral vestibular dysfunction due to autoimmune inner ear disease was given equilibrium exercises by a physical therapist. The patient mainly complained of dizziness and unsteadiness in walking. She started her rehabilitation program for her vestibular dysfunction at 4 years after the onset of her complaints. She lay on a bed with a posture like a bow, curved to the left. She sat on a chair tilting to the left and recognized the line which deviated to the left as being perpendicular. The deviation at sitting might be caused due to subjective vertical deviation. We instructed her to be aware that her perpendicularity was deviated to the left and to remain aware of that deviation whenever she did anything during her activities of daily living. She was given a rolling exercise on a mat. She also performed a sitting exercise on a chair at the corner of the room, touching the walls with both her shoulders. As she sensed the walls with her shoulders, she could sit perpendicularly by using her superficial and deep feelings. She was additionally given a standing and walking exercise. In order to relearn how to stand and walk without deviation, she stood between two panels which were situated in parallel with the width between them just a little wider than the breadth of her shoulders. She could stand upright and walk straight by using her superficial and deep feelings through touching the panels with her shoulders. She was advised to watch her toes when stepping forward in order to walk straight. She was instructed to be aware of the shift of the pressure on the soles of her feet while walking. She was able to stand and walk without deviation at the time of hospital discharge.

Vestibular and taste disorders after bilateral cochlear implantation

The objective of this study was to investigate the occurrence of vestibular receptor deficiency and taste disorders after bilateral cochlear implantation in postlingually deafened patients and to find out whether the risk for these complications is higher for the second implantation. In a retrospective cohort study, we examined 20 patients (11-58 years, mean age 41.5 years), implanted sequentially between 2000 and 2007 (mean period between cochlear implantation 32.9 ± 25 months). Pre- and postoperative vestibular testing was performed by subjective rating [Dizziness Handicap Inventory (DHI)], caloric irrigation [vestibuloocular reflex (VOR)] and by vestibular-evoked myogenic potential (VEMP) recordings for saccular function. The sense of taste was evaluated pre- and postoperatively by a questionnaire and testing (sour/sweet/bitter/salty bilaterally on the tongue). DHI evaluation showed a moderate not significant mean increase by 2.7 ± 7.7 SD points after the first and a significant increase by 9.4 ± 16.6 SD points after the second implantation. Ipsilateral VEMP responses disappeared in three ears (27.3%) after the first and in two ears (18.2%) after the second operation. VOR disappeared only once (5.9%) after the first implantation. One (5%) patient complained of a persisting disturbance of taste in the questionnaire after unilateral and 3 (15%) after bilateral implantation. Specific testing showed in one case (5%) a unilateral taste disorder after ipsilateral cochlear implantation. Our data show that there is a higher risk for subjective vertigo after the second implantation. The occurrence of unilateral and/or bilateral vestibular dysfunction and the potential risk of taste disorder should be included in the risk counseling before bilateral cochlear implantation to increase patients' and medicolegal safety in the decision-making process.

Bilateral progressive hearing loss and vestibular dysfunction with inner ear antibodies

Autoimmune inner ear disease (AIED) is a clinical syndrome of uncertain etiology. We present the neuro-otological findings of 2 cases of bilateral hearing loss, dizziness and the antibody profiles of the inner ears. Case 1 had bilateral progressive hearing loss, vestibular dysfunction and abnormal eye movement as the disease progressed. She had inner ear antibodies against 42 and 58 kDa protein antigency on Western blot immune assay, and responded to glycocorticosteroid but not to immunosuppressant treatment. Intratympanic steroid injection temporally eliminated her symptoms. However, she developed idiopathic Cushing's syndrome and underwent labyrinthectomy. Case 2 became deaf as a teenager and experienced dizziness 10 years after becoming deaf. He reacted strongly to 68 kDa protein and was a good responder to immunosuppressant with steroid. As we still lack a definitive diagnostic test for AIED, careful observation of the clinical course is critical for differential diagnosis regarding the bilateral progressive hearing loss.

Mitochondrial 12S rRNA susceptibility mutations in aminoglycoside-associated and idiopathic bilateral vestibulopathy

The mitochondrial 12S rRNA is considered a hotspot for mutations associated with nonsyndromic (NSHL) and aminoglycoside-induced hearing loss (AIHL). Although aminoglycoside ototoxicity is the most common cause of bilateral vestibular dysfunction, the conceivable role of 12S rRNA mutations has never been systematically investigated. We sequenced the 12S rRNA of 66 patients with bilateral vestibulopathy (BV) with (n=15) or without (n=51) prior exposure to aminoglycosides, as well as 155 healthy controls with intact vestibular function (sport pilots), and compared these to 2704 published sequences (Human Mitochondrial Genome Database). No mutations with a confirmed pathogenicity were found (A1555G, C1494T), but four mutations with a hitherto tentative status were detected (T669C, C960del, C960ins, T961G). Due to their predominant occurrence in patients without aminoglycoside exposure, their detection in controls and a weak evolutionary conservation, their pathogenic role in vestibulocochlear dysfunction remains provisional.

Susceptibility genes for gentamicin-induced vestibular dysfunction

Background: Approximately 5% of patients administered gentamicin (GM), an aminoglycoside antibiotic, experience vestibular ototoxicity resulting in balance dysfunction. In the present study, we sought to identify susceptibility genes associated with GM-induced vestibular dysfunction using a case/control design. Methods: White cases (n = 137; 55 men, 82 women) were recruited based on physician-confirmed unilateral or bilateral vestibular dysfunction attributed to GM administration. Controls (n = 126; 54 men, 72 women) were healthy, age-matched individuals without vestibular dysfunction or balance impairment. Buccal cell samples were obtained from all subjects and DNA was genotyped for 15 polymorphisms in 9 genes. Candidate genes were identified primarily for their roles in oxidative stress based on predicted mechanisms of gentamicin-induced ototoxicity. Statistical analyses included the multi-dimensionality reduction (MDR) method for identifying gene x gene interactions across multiple candidate genes. Results: Both single gene and MDR analyses revealed the NOS3 (ENOS) p.Glu298Asp polymorphism as significantly associated with GM-induced vestibular dysfunction (both p ⩽ 0.03). MDR analysis revealed a three-gene combination, consisting of NOS3 (p.Glu298Asp), GSTZ1 (p.Lys32Glu), and GSTP1 (p.Ile105Val), that provided the highest predictive model for GM-induced vestibular dysfunction (64% accuracy; p = 0.009). Conclusions: The results indicate that carriers of risk alleles at three oxidative stress-related genes have increased susceptibility to GM-induced vestibular dysfunction.

The clinical utility of search coil horizontal vestibulo-ocular reflex testing

Conclusion. Testing of the horizontal vestibulo-ocular reflex (VOR) with head rotations (including head impulses) using the magnetic scleral search coil technique (SCT HHI) provides valuable additional diagnostic information in patients with persistent dizziness, oscillopsia or imbalance. It identifies high and low frequency/acceleration vestibular abnormalities that are frequently missed using other methods. Objectives. To evaluate the diagnostic utility of SCT measurement of the horizontal VOR in the multidisciplinary neurotology clinic of a tertiary referral centre. Patients and methods. The records of 127 consecutive patients referred for persistent dizziness, oscillopsia, imbalance, or with clinical findings suggestive of high frequency/acceleration vestibular dysfunction were reviewed. All had been tested with clinical head impulses, bithermal calorics and vestibular-evoked myogenic potentials. VOR gain (peak eye velocity/peak head velocity) had been measured both in response to sinusoidal oscillations in a rotating chair (0.1–11Hz) and to manually delivered horizontal head rotations (peak head velocities 50–500°/s) using SCT. Results. Agreement between the different test modalities of horizontal semicircular canal function was moderate. Relative to SCT HHI, clinical HHI showed the highest sensitivity and the lowest specificity (both 70%). SCT HHI appeared to have the greatest diagnostic yield, when compared with calorics and SCT ROT (23% of all abnormalities shown were detected only by SCT HHI) and also allowed detection of significant asymmetries in patients with bilateral vestibular dysfunction.

Susceptibility genes for gentamicin‐induced vestibular dysfunction

Background: Approximately 5% of patients administered gentamicin (GM), an aminoglycoside antibiotic, experience vestibular ototoxicity resulting in balance dysfunction. In the present study, we sought to identify susceptibility genes associated with GM-induced vestibular dysfunction using a case/control design. Methods: White cases (n = 137; 55 men, 82 women) were recruited based on physician-confirmed unilateral or bilateral vestibular dysfunction attributed to GM administration. Controls (n = 126; 54 men, 72 women) were healthy, age-matched individuals without vestibular dysfunction or balance impairment. Buccal cell samples were obtained from all subjects and DNA was genotyped for 15 polymorphisms in 9 genes. Candidate genes were identified primarily for their roles in oxidative stress based on predicted mechanisms of gentamicin-induced ototoxicity. Statistical analyses included the multi-dimensionality reduction (MDR) method for identifying gene x gene interactions across multiple candidate genes. Results: Both single gene and MDR analyses revealed the NOS3 (ENOS) p.Glu298Asp polymorphism as significantly associated with GM-induced vestibular dysfunction (both p 0.03). MDR analysis revealed a three-gene combination, consisting of NOS3 (p.Glu298Asp), GSTZ1 (p.Lys32Glu), and GSTP1 (p.Ile105Val), that provided the highest predictive model for GM-induced vestibular dysfunction (64% accuracy; p = 0.009). Conclusions: The results indicate that carriers of risk alleles at three oxidative stress-related genes have increased susceptibility to GM-induced vestibular dysfunction.

Aseptic Meningoencephalitis Presenting with Bilateral Vestibular Ataxia: a Case Report

Bilateral vestibular dysfunction is a rare condition, of which peripheral disorders are most common, whereas central disorders are extremely rare. A 35-year-old woman developed fever, headache, dizziness, convulsion, and disturbance of consciousness at the same time. MRI findings were normal. Based on the neurological findings and laboratory abnormalities, she was diagnosed as having aseptic meningoencephalitis. Steroid pulse therapy successfully ameliorated her encephalitis sign. However, isolated bilateral vestibular ataxia and dizziness, together with severe decrease of Caloric nystagmus, became apparent and lasted for the following 3 months, without cerebellar/brainstem involvement.

Patient and Normal Three-dimensional Eye-Movement Responses to Maintained (DC) Surface Galvanic Vestibular Stimulation

That disease or dysfunction of vestibular end organs in human patients will reduce or eliminate the contribution of the affected end organs to the total eye-movement response to DC surface galvanic vestibular stimulation (GVS). It was assumed that DC GVS (at current of 5 mA) stimulates all vestibular end organs, an assumption that is strongly supported by physiological evidence, including the activation of primary vestibular afferent neurons by galvanic stimulation. Previous studies also have described the oculomotor responses to vestibular activation. Stimulation of individual semicircular canals results in eye movements parallel to the plane of the stimulated canal, and stimulation of the utricular macula produces changes in ocular torsional position. It was also assumed that the total three-dimensional eye-movement response to GVS is the sum of the contributions of the oculomotor drive of all the vestibular end organs. If a particular vestibular end organ were to be diseased or dysfunctional, it was reasoned that its contribution to the GVS-induced oculomotor response would be reduced or absent and that patients thus affected would have a systematic difference in their GVS-induced oculomotor response compared with the response of normal healthy individuals. Three-dimensional video eye-movement recording was carried out in complete darkness on normal healthy subjects and patients with various types of vestibular dysfunction, as diagnosed by independent vestibular clinical tests. The eye-movement response to long-duration bilateral and unilateral surface GVS was measured. The pattern of horizontal, vertical, and torsional eye velocity and eye position during GVS of patients independently diagnosed with bilateral vestibular dysfunction, unilateral vestibular dysfunction, CHARGE syndrome (semicircular canal hypoplasia), semicircular canal occlusion, or inferior vestibular neuritis differed systematically from the responses of normal healthy subjects in ways that corresponded to the expectations from the conceptual approach of the study. The study reports the first data on the differences between the normal response to GVS and those of patients with a number of clinical vestibular conditions including unilateral vestibular loss, canal block, and vestibular neuritis. The GVS-induced eye-movement patterns of patients with vestibular dysfunction are consistent with the reduction or absence of oculomotor contribution from the end organs implicated in their particular disease condition.

Influence of acute unilateral vestibular lesions on the respiratory rhythm after active change of posture in human subjects

The influence of acute unilateral vestibular lesions on respiratory rhythm after active change of posture, was evaluated by comparing responses from patients with acute vestibular neuritis, with those from normal subjects with minor injuries other than vestibular (e.g. epistaxis, headache) and patients with chronic bilateral vestibular dysfunction. Respiratory movements of the thorax-abdomen were recorded during 5 minutes in supine position, 5 minutes of back-unsupported sitting and 5 minutes of upright stance. Compared to supine position, sitting-up induced different responses in each group (p < 0.05, ANOVA). The healthy subjects showed a consistent decrease in the mean respiratory frequency related to an increase of the expiration time, which was absent in patients with vestibular neuritis. Subjects with minor injuries showed the opposite changes of expiration time and inspiration time with no change of the respiratory frequency and patients with bilateral vestibular dysfunction showed a trend to increase their respiratory frequency. Standing-up did not evoke any further changes in any group. We conclude that the vestibular system modulates the respiratory response to reorientation of the head and trunk to upright position and this influence is reduced during the acute stage of a vestibular lesion.

Rats with lesions of the vestibular system require a visual landmark for spatial navigation

The role of the vestibular system in acquisition and performance of a spatial navigation task was examined in rats. Male Long-Evans rats received sham or bilateral sodium arsanilate-induced vestibular lesions. After postoperative recovery, under partial water-deprivation, rats were trained (16 trials/day) to find a water reward in one corner of a black square enclosure. A cue card fixed to one wall of the enclosure served as a stable landmark cue. The orientation of the rat at the start of each trial was pseudo-randomized such that the task could not be solved by an egocentric response strategy. Rats with vestibular lesions acquired the task in fewer trials than the sham treated control rats. Vestibular lesions did not influence the motivation or motor function necessary to perform the task. Performance of sham rats was maintained during probe trials in which the cue card was removed from the enclosure, while lesioned rats were markedly impaired. Rotation of the cue card (±90°) caused an equivalent shift in corner choice behavior of the lesioned rats. However, sham rats often disregarded the rotated cue card and made place responses. These results suggest that the vestibular lesions disrupt idiothetic navigation or path integration and render navigational behavior critically dependent upon external landmarks. These results are consistent with the navigational abilities of humans with bilateral vestibular dysfunction.

急激な両側前庭機能低下と難聴を呈した１例

Although unilateral loss of hearing and vestibular function is relatively common, bilateral auditory and vestibular dysfunction rarely occurs. We report a patient with bilateral auditory and vestibular dysfunction with simultaneous onset and describe the otological manifestations of this case. A 54-year-old man was admitted to hospital complaining of headache and fever. After hospitalization, he experienced vertigo, which consisted of a sensation of moving vertically and noticed bilateral hearing loss, which increased gradually. The patient was referred to our University Hospital because vertigo and hearing loss persisted after therapy, although his headache and fever improved. On the first visit to our clinic, skin eruptions suggestive of herpes virus infection were noted on the right cheek and around the angles of the mouth. Pure-tone audiometry revealed moderate to severe bilateral sensorineural hearing loss. Right-beating nystagmus with horizontal and torsional components was observed on gaze, positional and positioning nystagmus tests. A caloric test showed severe hypofunction of the bilateral semicircular canals. Hematological examination revealed an elevated antibody titer against herpes simplex virus. Steroid tapering treatment and prostaglandin treatment were performed and the he hearing level improved to 63.8dB on the right and 32.5dB on the left, and nystagmus on gaze, positional and positioning conditions disappeared. A caloric test after therapy showed mild canal dysfunction on the right and severe canal palsy on the left. At present, the patient does not have any marked disabilities in daily life. We speculated that the sudden loss of bilateral auditory and vestibular function was caused by herpes simplex viral meningitis because of the skin eruptions on the face and elevated antibody titer against herpes simplex virus.

Dynamic visual acuity while walking in normals and labyrinthine-deficient patients

We describe a new, objective, easily administered test of dynamic visual acuity (DVA) while walking. Ten normal subjects and five patients with histories of severe bilateral vestibular dysfunction participated in this study. Subjects viewed a visual display of numerals of different font sizes presented on a laptop computer while they stood still and while they walked on a motorized treadmill. Treadmill speed was adapted for 4 of 5 patients. Subjects were asked to identify the numerals as they appeared on the computer screen. Test results were reasonably repeatable in normals. The percent correct responses at each font size dropped slightly while walking in normals and dropped significantly more in patients. Patients performed significantly worse than normals while standing still and while walking. This task may be useful for evaluating post-flight astronauts and vestibularly impaired patients.

Objective criteria for expert assessment of vestibular vertigo

Even for experienced examiners quantitative and objective medicolegal assessment of vestibular vertigo is difficult. Current medicolegal opinions place disproportionate emphasis of subjective symptoms. Based on parameters from spontaneous and provoked vestibular nystagmus with Frenzel's glasses, objective criterias for adequate medicolegal assessment of vestibular disorders are presented. Diagrams in tabular form for unilateral and bilateral vestibular dysfunction and benign peripheral positional vertigo allow assessment of reduction in earning capacity. The widespread use of subjective criteria in the medicolegal evaluation of vestibular complaints should not be accepted. The qualified ENT specialist is able to evaluate vestibular deficits using objective and reproducible methods.

めまい・平衡障害例の平衡訓練成績

Some patients with acute or chronic vestibular disorders continue to complain of dizziness and disequilibrium. Although treated with medication, their activities of daily living (ADL) and occupational activities are restricted. Equilibrium training is applied to reduce the disability of the patients.Methods: Before training is started, the degree of impairment, disability and handicaps of the patients were evaluated. To evaluate subjective and objective disabilities, the ADL were investigated by questionnaire and equilibrium function tests were performed.Three times a day at home, patients performed several somewhat difficult exercises selected from their defective movements. Training continued until their disabilities were reduced.The effects of training were assessed by ADL, equilibrium function tests, stabilometry and gait test.Subjects: The subjects were 8 patients with unilateral vestibular disorders, 4 with postoperative acoustic neurinoma, and 8 with bilateral vestibular disorders.Results: Equilibrium training was effective in all 8 patients with unilateral vestibular dysfunction, in all 4 patients with postoperative acoustic neurinoma, and in 7 of the 8 with bilateral vestibular dysfunction. It was difficult to evaluate the effect of the training in a case of bilateral Meniere's disease.Conclusion: We found many differences in disability among patients with similar impairments, and were able to plan an individual training program suitable for each patient. ADL and equilibrium function tests were useful for evaluating disability and the effect of training.We considered equilibrium training effective for patients with unilateral vestibular disorders who showed chronic disability persisting for more than several weeks after onset, for patients with postoperative acoustic neurinoma who had persistent disability 4 weeks after surgery and for patients with bilateral vestibular disorders with disability persisting for more than 8 weeks.

The caloric stimulus: mechanisms of heat transfer

This review is concerned with the physical processes involved in thermal stimulation of the vestibular end-organ. A brief outline of the anatomy of the end-organ is given with particular reference to the horizontal semicircular canal, followed by a description of end-organ hydrodynamics. The neurophysiological mechanisms of thermal stimulation are then considered. Finally, routes of heat transfer from outer to inner ear are discussed.

Spatial learning in an enclosed eight-arm radial maze in rats with sodium arsanilate-induced labyrinthectomies

Bilateral vestibular dysfunction was induced in Long-Evans male rats (n = 7) by intratympanic injections of sodium arsanilate (30 mg/side). Control rats (n = 6) received isotonic saline. Animals were tested for labyrinthine integrity by measuring air-righting and contact-righting reflexes. Rats were reduced to 85% of free-feeding body weight and tested in an enclosed 8-arm radial maze (1 trial/day over 10 days). Labyrinthectomized animals made significantly more errors (p < .001) and, unlike the controls, showed no significant improvement on this measure over acquisition training. These rats also made significantly more (p = 0.018) sequential same arm reentries and fewer sequential adjacent arm entries (p < .01). These findings demonstrate that information obtained from the vestibular system is very important in spatial learning in the rat.