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Quantitative analysis of the visual vestibulo-ocular reflex using sinusoidal rotation in patients with peripheral vestibular disorders.

In order to investigate interaction of the vestibular and optokinetic systems in patients with peripheral vestibular disorders, the visual vestibulo-ocular reflex (V-VOR) gain in 49 patients with peripheral vestibular disorders was quantitatively measured by using pendular harmonic sinusoidal rotation with optokinetic stationary stimuli. The patients were rotated sinusoidally both with eyes closed and open at an amplitude of 240 degrees and at a frequency of 0.1 Hz (peak velocity 75.4%s). Comparing the vestibulo-ocular reflex (VOR) and V-VOR gains in the patients with definite Meniere's disease (23 cases), benign paroxysmal positional vertigo (BPPV, 13 cases) and sudden deafness with vertigo or dizziness (13 cases), the VOR-DP and normal V-VOR gain were more frequently observed in patients with Meniere's disease (13 cases) and sudden deafness (7 cases) than in those with the BPPV (3 cases). In the four patients with bilateral Meniere's disease and sudden deafness, abnormally decreased VOR-gain (under 0.55) in the bilateral directions with slightly decreased V-VOR gain was measured when tested independently. However, abnormal V-VOR gain was observed in only one case of sudden deafness due to retrocochlear lesions. From our VOR and V-VOR gain observations comparing the caloric responses, we have concluded that the comparison of VOR with V-VOR gains provides additional information for evaluation of peripheral vestibular disorders as well as central nervous system disorders.

Computers↗

Recovery from unilateral vestibular nerve section in human subjects evaluated by physiological, psychological and questionnaire assessments.

Patients undergoing vestibular nerve section for vertigo or acoustic neuroma surgery were compared pre- and post-operatively and during long-term follow-up using a range of tests including: nystagmography, impulsive rotational testing of the vestibulo-ocular reflex (VOR), ability to estimate and reproduce imposed rotational displacements, validated questionnaires rating vertigo, imbalance, autonomic reactivity and somatisation, and clinical and self-assessment scales of overall outcome in terms of symptoms and disability. Correlations were found between rating scale assessments, questionnaire scores and estimates of self-rotation. Neither nystagmography nor VOR tests correlated with the presence or severity of vertigo or imbalance. Post-operatively, vertigo patients reported that they had received significant relief, although they had higher incidences of residual complaints of imbalance and vertigo than patients after acoustic neuroma surgery. Factors impeding rehabilitation in patients with vertigo are discussed.

Adaptation, Physiological↗

Dizziness of suspected cervical origin distinguished by posturographic assessment of human postural dynamics.

Useful clinical tests are lacking for the controversial entity "cervical vertigo". In earlier studies patients assumed to suffer from cervical vertigo or dizziness manifested disturbed postural control as compared to healthy subjects, but were hard to distinguish from patients with other balance disorders. Using posturography in which stance was perturbed by a vibratory stimulus applied towards the calf muscles, we studied 16 consecutive patients with recent onset of neck pain and concomitant complaints of vertigo or dizziness, but normal findings at otoneurological examination and electronystagmography; 18 patients with recent vestibular neuritis; and 17 healthy subjects. We performed system identification of a model of the control of upright human stance, using the vibratory stimulus as input and the recorded body sway as output. According to values for the three normalized parameters of the transfer function of the model (i.e., swiftness, stiffness, and damping), cervical vertigo patients were distinguished both from healthy subjects (P < 0.001), and from vestibular neuritis patients (P < 0.001). It was also possible to distinguish the vestibular neuritis group from the group of healthy subjects (P < 0.01). The results show disturbed postural control in patients with cervical vertigo to differ from that in patients with recent vestibular neuritis, and indicate posturographic assessment of human posture dynamics to be a possible future tool for use in diagnosing cervical vertigo.

Adult↗

The effect of roll-tilt on ocular skew deviation.

Static roll-tilt of normal healthy subjects causes the ocular tilt reaction (OTR) one component of which is disconjugate vertical eye position (skew deviation). In this study the magnitude of skew was measured subjectively by the use of a computerized Hess test at three static roll-tilt angles (head erect, left ear down and right ear down) and two viewing distances (20 cm and 60 cm). The results showed that during static roll-tilt there was a small skew deviation, the magnitude of which was increased at close viewing distances.

Afferent Pathways↗

Three cases of cochleosaccular endolymphatic hydrops without vertigo revealed by furosemide-loading vestibular evoked myogenic potential test.

OBJECTIVE: To describe possible cases of cochleosaccular endolymphatic hydrops without vertigo. STUDY DESIGN: Retrospective case report. SETTING: University hospital. PATIENTS: Three patients with possible cochleosaccular hydrops without vertigo were studied. The basis of diagnosis was positive result of the furosemide-loading vestibular evoked myogenic potential test, no canal paresis in the caloric test, and recurrent cochlear symptoms or fluctuating low-tone hearing loss. CASE REPORT: In case 1, a 47-year-old woman had recurrent left aural fullness and tinnitus and a few weeks later complained of a floating sensation and could not stand up. The furosemide-loading vestibular evoked myogenic potential test showed a positive result in the left ear. In case 2, a 24-year-old woman complained of a backward falling sensation lasting several seconds; subsequently, a severe floating sensation persisted and she could not stand up for several days. Audiography showed fluctuating low-tone hearing loss in the left ear, and the furosemide-loading vestibular evoked myogenic potential test showed a positive result. In case 3, a 41-year-old woman had a floating sensation while walking and subsequently complained of tinnitus in the left ear. She could not stand up because of a severe floating sensation and, moreover, complained of a sudden falling sensation lasting for several seconds. The furosemide-loading vestibular evoked myogenic potential test indicated a positive result in the left ear. CONCLUSIONS: The patients in cases 2 and 3 complained of a short-lasting sensation of falling down. Severe disequilibrium that prohibited standing up was noted in all cases. It was suggested that these symptoms were caused by saccular hydrops.

Adult↗

Auditory and vestibular system findings in patients with vertebrobasilar dolichoectasia.

Impairment of the auditory-vestibular system has been reported in patients with vertebrobasilar dolichoectasia (VBD), but little is known about the underlying cause of the symptoms. Auditory testing (pure tone audiometry, auditory brain stem response and stapedius reflex) and vestibular tests (assessment of nystagmus, eye tracking tests, caloric test and rotational test) were performed in 23 patients with auditory-vestibular symptoms and/or cranial nerve impairment associated with VBD. Specific evidence of auditory and/or vestibular system impairment was observed in 19 cases (83%). Among patients with abnormal test findings, 47% had evidence suggesting peripheral impairment, 16% evidence suggesting central dysfunction, and 37% evidence suggesting both peripheral and central dysfunction. Although compression of the vestibulocochlear nerve plays an important role in the genesis of the auditory-vestibular dysfunction in patients with VBD, mechanism such as brain stem-cerebellar ischemia and impaired blood supply to the vestibular labyrinth may be just as important.

Aged↗

[Central nervous system influences on vestibulo-ocular and vestibulospinal functions exemplified by hand dominance].

The influence of the hand dominance and the hemispheric dominance on vestibulo-ocular and vestibulo-spinal responses was investigated. 40 healthy voluntary soldiers between 18 and 22 years old who were known to be left handed were examined. A special psychomotoric test was performed for quantification of the hand dominance. Spontaneous nystagmus, vestibulo-ocular reflex after caloric and pendular stimulation, vestibulo-spinal tests and pure-tone audiogram were recorded. Directional preponderance to the left side was observed in most of the left handed subjects. Spontaneous nystagmus was directed to the left in subjects with extreme left hand dominance. There were no side differences in the caloric test nor in the pendular tests. Orientation in the Unterberger's stepping test was up to 200 degrees to the left. With increasing left handed dominance the intensity of directional preponderance, spontaneous nystagmus and body rotation to the left side also increased. Variation of the normal VOR and vestibulo-spinal responses due to central nervous influences is obvious. Directional preponderance and vestibulo-spinal responses should therefore be carefully estimated in clinical diagnosis.

Adolescent↗

A quantitative analysis of head-shaking nystagmus of peripheral vestibular origin.

A quantitative analysis of horizontal head-shaking nystagmus (HSN) was made on 48 patients with unilateral peripheral vestibular lesions in conjunction with stimulus intensity. Each patient underwent three head-shaking tests with 10, 30 and 50 horizontal head-excursions at a frequency of approximately 2 Hz, and HSN was recorded on ENG with eyes open in total darkness. i) HSN appeared in a biphasic or monophasic pattern. ii) The maximal slow-phase eye velocity (MSV) of the 1st phase (PI) of biphasic HSN increased significantly in proportion to stimulus intensity, and was significantly greater than that of monophasic HSN. iii) The duration of HSN was greater in the 2nd phase (PII) of biphasic HSN than in PI and increased markedly in proportion to stimulus intensity. iv) As the stimulus intensity rose to a high level, the interval between PI and PII (2nd phase latency) shortened, and the PII tended to appear more quickly after head-shaking. It was especially noteworthy that in response to an increase in stimulus intensity, both the MSV in PI and the duration of PII of biphasic HSN increased, but the duration of PI was reversely suppressed by the PII.

Adolescent↗

Mechanism of posterior semicircular canal stimulation in patients with benign paroxysmal positional vertigo.

A quantitative study of the stimuli and vestibulo-ocular response associated with benign paroxysmal positional vertigo (BPPV) was made to test and further develop the canalithiasis theory of BPPV. The angular velocities of the head in the planes of the semicircular canals during the Dix-Hallpike test were measured in four healthy subjects using electromagnetic sensors to record the position of the head in a six degrees of freedom paradigm. Next, the nystagmus reactions in seven patients diagnosed with idiopathic BPPV were recorded with video-oculography. The characteristics of the vestibulo-ocular reflex (VOR) response were analyzed using three-dimensional vector techniques. The angular velocity of the head was primarily, but not exclusively, in the plane of the posterior semicircular canal (PSC) in question. Both the anterior and horizontal canals were also stimulated by a lesser degree. The duration of the motion stimulus in the PSC was < 1.3 s with peak angular velocities of 150 deg/s. The eye response in BPPV patients began 4 s after the test and had a duration of 15-20 s. Peak slow-component eye velocities of about 42 deg/s were reached 3-5 s after onset of nystagmus. The motion of the eye, as predicted by the cupulolithiasis theory, is disconjugated and has torsional, vertical, and horizontal components. In the eye ipsilateral to the tested ear it is primarily torsional (0.80, 0.54, 0.16) and in the contralateral eye it is mainly vertical (0.57, 0.73, 0.08). These results suggest that particles, initially resting on the floor of the cupula dome in the PSC, are perturbed by the Dix-Hallpike test and disperse freely into the endolymph where they are propelled by gravity into the canal lumen. This creates abnormal pressure on the cupula and the specific VOR activation of the ipsilateral superior oblique and the contralateral inferior rectus muscles, whose force vectors are indistinguishable from the measured eye motion vectors. The estimated pressure exerted on the crista is approximately 10(-2) dyn/cm2.

Adult↗

Lesion site in idiopathic bilateral vestibulopathy: a galvanic vestibular-evoked myogenic potential study.

CONCLUSION: The result suggests that patients with idiopathic bilateral vestibulopathy may have nerve lesions when the inferior nerve system is affected, while the inferior vestibular nerve system may be spared. OBJECTIVE: To clarify the lesion site in idiopathic bilateral vestibulopathy, an acquired bilateral vestibulopathy of unknown cause. MATERIAL AND METHODS: Two 75-year-old males diagnosed with idiopathic bilateral vestibulopathy were enrolled. Both showed absent or highly decreased responses on the caloric test on both sides. They underwent vestibular-evoked myogenic potential (VEMP) testing by means of acoustical and electrical stimulation. As acoustic stimulation, 95 dB nHL clicks and short tone bursts (500 Hz) were presented, while 3 mA (1 ms) short-duration galvanic stimuli were presented as electrical stimulation. Responses were recorded on the sternocleidomastoid muscles. RESULTS: Both patients showed unilateral absence of VEMPs with both acoustic and short-duration galvanic stimuli.

Acoustic Stimulation↗

Peripheral and central vestibular disorders in alcoholics. A three-year follow-up study.

Vestibular disorders were found in all 33 Japanese men who had been drinking alcohol for over 20 years and who had abstained from alcohol for over 3 months before the tests were done. Six, 12, and 15 patients showed peripheral, central, and combined types of vestibular disorders, respectively. The peripheral disorder occurred in younger alcoholics (under 50 years old) with a drinking history of 20-30 years, and the combined disorder in older patients with a longer drinking history. The vestibular disorders, however, were not observed in any of 16 control non-alcoholics. A follow-up study on seven alcoholics with a 3-year abstinence from alcohol revealed an improvement of vestibular dysfunctions, in particular of peripheral disorders, with an abstinence of over 2 years.

Adult↗

Objective evaluation of the effect of flunarizine on vestibular neuritis.

OBJECTIVE: To determine whether vestibular autorotation tests (VAT) would show significant differences in vestibular oculomotor reflex (VOR) parameters in vertiginous patients before and after treatment with flunarizine. STUDY DESIGN: Prospective study in a tertiary referral academic center. METHODS: Twenty-three patients (10 men, 13 women, mean age 45.57 years, mean length of disease 99.48 days, mean treatment 38.61 days), with vertigo due to vestibular neuritis, underwent VAT testing before and after treatment with 5 mg of flunarizine daily. RESULTS: The parameter improvement value (IV) resulted from subtracting posttreatment from pretreatment VAT numerical values. Regarding subjective improvement, 3 patients (13%) said they had none, 5 (21.7%) expressed moderate progress, 9 (39.1) considered the results satisfactory, and 6 (26%) became asymptomatic. The VAT results gave high positive IV for horizontal restriction, low positive for horizontal and vertical gains and horizontal asymmetry, and negative IV for horizontal phase and vertical restriction. Regarding the individual frequencies, horizontal and vertical gains improved in all the frequencies tested except one. The horizontal phase improved at low frequencies (2.0 and 2.3 Hz) and deteriorated from 2.7 to 3.9 Hz. Vertical and horizontal restriction showed both improvement and deterioration. Horizontal asymmetry displayed improvement from -0.01 at 2.0 Hz to 0.50 at 5.9 Hz, deteriorating from -0.41 at 9.0 Hz. CONCLUSIONS: Flunarizine is useful in the treatment of vertigo caused by vestibular neuritis. VAT is a valid instrument for the objective and quantitative evaluation of the vestibular-oculomotor reflexes.

Administration, Oral↗

Unilateral vestibular neuritis with otolithic signs and off-vertical axis rotation.

Off-vertical axis rotation (OVAR) at constant velocity is a dynamic otolith stimulus that induces horizontal and vertical eye movement responses. To determine the value of this examination as a test for unilateral otolithic hypofunction, we compared the OVAR responses of patients suffering from acute vestibular neuritis (VN) without any sign of otolith affection, with those of patients suffering from acute VN with otolithic signs. The horizontal eye movement bias component shows directional preponderance (DP) significantly higher in patients with otolithic signs than in patients not presenting them. However, as bias DP also reflects the imbalance between right and left horizontal canals activity, this greater bias DP could be explained by the more severe canals impairment-evaluated by caloric test-found in patients with otolithic signs. No significant difference can be shown on horizontal modulation. The DP of vertical modulation is significantly higher in patients presenting otolithic signs than in patients not presenting them: in the case of otolithic signs, the responses are smaller during rotations toward the affected side. Therefore, this variable could be used as an indication of unilateral otolithic hypofunction.

Adult↗

[Galvanic stimulation of the vestibular system: indications and determination of normal values based on the frequency of the slow nystagmus phase].

The most important features of the galvanic test are the persistence of galvanic nystagmus after complete destruction of the labyrinth and its impairment as soon as the peripheral neurone is damaged. 25 normal subjects, 4 patients with an acoustic neuroma and 4 patients with Menière's disease were investigated. A difference in slow phase velocity between the right and left sides of more than 22% indicates a lesion of the vestibular nerve. In patients with an acoustic neuroma the difference lay between 59% and 100%. In Menière's disease the difference measured was between 1% and 15%.

Cholesteatoma↗

Vestibular neuronitis--its clinical characteristics.

Several parts of a nationwide survey of the epidemiology of vestibular neuronitis were reported. Follow-up studies of vestibular neuronitis were made. The computed galvanic body-sway test (Yamaguchi University) obtained from 10 patients with vestibular neuronitis showed a peculiar 'slow and sluggish' pattern. In the course of the illness, this slow and sluggish pattern changed its appearance and soon resembled the pattern obtained from the opposite, healthy side. Improvement of the abnormal pattern was observed in 7 patients (observation period 6 months to 6 years, averaging 33 months). 3 other patients (observation period 1 month to 1 year, averaging 5.3 months) showed no improvement in the pattern. These findings suggest that the conductivity of the vestibular nerve affected by vestibular neuronitis has an increasing chance for recovery.

Adolescent↗

Magnitude effects of galvanic vestibular stimulation on the trajectory of human gait.

This study examines the contribution of the vestibular system during different magnitudes of galvanic vestibular stimulation (GVS) during human walking. Anodal threshold levels of GVS were determined for right and left sides for each subject. Seven conditions were tested (no stimulation, left and right anode stimulation) at one, two and three times threshold. GVS was delivered to the mastoid processes at first heel contact and continued for the duration of the trial. All subjects responded by deviating towards the anode while walking. In addition, the magnitude of deviation increased as the stimulus intensity increased. Our results demonstrate that the vestibular system is sensitive to GVS intensity changes and responds by altering the magnitude of the response accordingly. These data provide a strong argument in support of a significant role for vestibular information during dynamic tasks.

Adult↗

Imaginary gaze effects on eye movements induced by linear acceleration: involvement of vestibular induced smooth pursuit eye movement.

We investigated smooth eye movements elicited i) by linear acceleration in a space-fixed imaginary gaze condition (smooth component of eye movement induced by linear motion: LSEM) and ii) during acoustic pursuit of a moving sound source (smooth component of eye movement induced by acoustic pursuit of a sound source: SSPEM). The two conditions were examined using the same test subjects. LSEM and SSPEM performance was found to be positively correlated across the subject population. From the comparison of LSEM and SSPEM we propose the following hypothesis: LSEM consists not only of a pure translational vestibular-ocular reflex (tVOR) component but also of a component based on the perception of otolithic information. Accordingly, this second component is instrumental in the pursuit of an imaginary visual target during linear self-motion.

Acceleration↗

3-D eye movement measurements on four Comex's divers using video CCD cameras, during high pressure diving.

Previous studies have shown the vulnerability of the vestibular system regarding barotraumatism (1) and deep diving may induce immediate neurological changes (2). These extreme conditions (high pressure, limited examination time, restricted space, hydrogen-oxygen mixture, communication difficulties etc.) require adapted technology and associated fast experimental procedure. We were able to solve these problems by developing a new system of 3-D ocular movements on line analysis by means of a video camera. This analyser uses image processing and forms recognition software which allows non-invasive video frequency calculation of eye movements including torsional component. As this system is immediately ready for use, we were able to realize the subsequent examinations in a maximum time of 8 min for each diver: oculomotor tests including saccadic, slow and optokinetic traditional automatic measurements; vestibular tests regarding spontaneous and positional nystagmus, and reactional nystagmus to the pendular test. For pendular induced nystagmus we used appropriate head positions to stimulate separately the lateral and the posterior semicircular canal, and we measured the gain by operating successively in visible light and complete darkness. Recordings were done during a simulated onshore dive to an ambient pressure corresponding to a depth of 350 m. The above examinations were completed on the first and last days by caloric tests with the same video system analyser. The results of the investigations demonstrated perfect tolerance of the oculomotor and vestibular systems of these 4 divers thus fulfilling the preventive conditions defined by Comex Co. We were able to overcome the limitations due to low cost PC computer operation and cameras (necessity of adaptation to pressure, focus difficulties and direct light exposure eye reflexions). We still have on line accurate measurements even on the torsional component of the eye movement. Due to this technological efficiency we also present some mathematical aspects of the software.

Adult↗