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We propose a new interface concept; Proprioceptive Menu with Tactons, an eyes- and ears-free menu in a proprioceptive space that uses a set of Tactons to describe its menu items. While previous proprioceptive menus utilized vibrotactile feedback only to express the boundary between menu items, we spot an unexplored possibility that distinct vibrotactile stimuli, Tactons, can be used to describe the status of each menu item. As an instance of this concept, we present WristMenu with Tactons, an eyes- and ears-free menu using a one-dimensional proprioceptive space of the axial wrist rotation. Users can grasp an overview of each menu item's status through Tactons delivered on their wrist skin and eventually decide to select the desired item. Our evaluation study showed that users could find a target item among five candidates and recognize its status in 5 seconds on average at the accuracies of 93% and 86% in seated and walking conditions, respectively. Through our evaluation, we could confirm the feasibility of the proposed concept. [ABSTRACT FROM AUTHOR]

Sudden sensorineural hearing loss with vertigo (SHLV) and vestibular neuritis (VN) can result in prolonged dizziness. This study aimed to compare the video head impulse test (vHIT) of patients with SHLV and VN. Fifteen patients with SHLV and 21 patients with VN who visited the Vertigo/Dizziness Center of our hospital between December 2016 and February 2023 were included. vHIT was performed at the time of admission, and the VOR gain and catch up saccade (CUS) in the three types of semicircular canals (SCCs) were analyzed. Pathologic vHIT results were observed most frequently in the posterior SCC (73%), followed by lateral (53%) and anterior (13%) SCCs in the SHLV group. In contrast, pathologic vHIT results were observed most frequently in the lateral SCC (100%), followed by the anterior (43%) and posterior SCC (24%) SCCs in the VN group. Pathological vHIT results in the lateral and posterior SCC showed significant differences between the two groups, but for anterior SCC, no significant differences were found. Comparison of the two vHIT results revealed differences in the SCC dysfunction patterns. This may be due to the different pathophysiological mechanisms of the two vestibular disorders, which may result in prolonged vertigo. [ABSTRACT FROM AUTHOR]

Vestibular stimulation causes postural unsteadiness accompanied by a sensation of tilt. The mechanism of the sensation of tilt needs to be assessed by accurate calculation of the rotational axis of torsional eye position under various vestibular stimulations. Twenty-two healthy subjects participated in the study. Thirteen subjects underwent bilateral vestibular stimulation by on-axis yaw rotation under various head positions, and eighteen subjects underwent unilateral vestibular stimulation by caloric irrigation under various head positions. Listing's Plane was plotted for the eye movement data obtained by three-dimensional video-oculography. The offset of Listing's Plane showed sustained deviation of torsional eye position that was more prominent in head positions that stimulated lateral semicircular canals more than vertical semicircular canals. There was a less prominent and directionally reversed offset in head positions that stimulated vertical canals more than lateral semicircular canals. The sustained torsional eye position was validated by accurate assessment using Listing's Plane. The mechanism behind the deviation may be due to a combination of multiple anatomical components within the vestibular apparatus, with potentially stronger influence from lateral semicircular canals. [ABSTRACT FROM AUTHOR]

Dynamic cervico- (COR) and vestibulo-ocular reflex (VOR) contribute to stabilise visual images in the retina. The gain in dynamic COR is small in healthy individuals but increases in patients with vestibular dysfunction. Conversely, static COR has not been directly observed in healthy individuals. To elucidate the presence of static COR and quantify it in normal individuals in the roll plane. Eleven healthy participants were included in the study. Eye torsions were measured using video oculography to evaluate the static COR induced by lateral neck flexion during a head-upright-with-body-tilt position at 15°, 30°, and 45°. The ocular counterroll (OCR) was compared during whole-body and head tilts to assess the influence of static COR on OCR. Static COR was significantly observed as eye torsion in the direction opposite to the body tilt. The head tilt OCR was significantly smaller than the whole-body tilt OCR to the right side but not to the left side. Static COR exists in healthy individuals and tends to show higher amplitude as neck flexion stimulation increases. [ABSTRACT FROM AUTHOR]

Bilateral vestibulopathy (BVP) is a chronic and potentially very disabling condition. The impact of the vestibular loss on quality of life (QoL) is variable and still up for discussion. However, previous studies have reported that BVP has a negative impact of QoL. The aim of the study was to evaluate the association between vestibulo-ocular reflex (VOR) gain and saccade pattern and patient reported QoL. Ten patients fulfilling the Bárány criteria of BVP were included in the study. All patients underwent vestibular evaluation using Head Impulse Paradigm (HIMP) and Suppression Head Impulse Paradigm (SHIMP) and responded to Dizziness Handicap Inventory (DHI). DHI was used as a measurement for QoL. Linear regression revealed a tendency to a correlation between lateral VOR-gain measured by HIMP or SHIMP and total DHI score. Covert saccades were related to low total DHI scores. No association was found between type of SHIMP saccade and QoL. No significant correlations were found. A tendency was found towards a relationship between lateral VOR-gain by HIMP or SHIMP and total DHI score. The study also indicates that covert saccades are related to low impact on QoL. [ABSTRACT FROM AUTHOR]

The aim of this study was to devise a novel test for assessing the cervico-ocular reflex (COR) system via head vibration (termed h-COR) or neck vibration (termed n-COR) method. Thirteen patients with complete loss of bilateral vestibulo-ocular reflex (VOR) showing oscillopsia were assigned to Group A, while 13 patients with bilateral VOR loss but no oscillopsia were Group B. Another 13 healthy elderly served as a control. The COR test was performed via modifying the ocular vestibular-evoked myogenic potential (oVEMP) test by tapping at the forehead with head rotation (h-COR) or at mid-dorsal neck with head straight (n-COR). Both h-COR and n-COR tests displayed similar cI–cII waveforms. None of the Group A or healthy elderly showed present h-COR, while 8% of Group A and 31% of the healthy elderly revealed present n-COR. In contrast, present h-COR and n-COR were elicited in 85 and 77% of Group B, respectively. Restated, significantly higher response rate of COR in Group B (without oscillopsia) than Group A (with oscillopsia) indicates that present COR is related to the alleviation of oscillopsia. Head vibration method (h-COR test) is superior to neck vibration method (n-COR test) for assessing the COR system. [ABSTRACT FROM AUTHOR]

Purpose:To identify the tests and tools used to evaluate vestibulo-ocular reflex (VOR) function after traumatic brain injury (TBI) in all age groups and across TBI severity. Methods: An electronic search was conducted to include relevant peer-reviewed literature published up to November 2019. Studies included those done with humans, of all ages, and had assessments of oculomotor and/or vestibulo-ocular function in TBI. Results: Of the articles selected (N = 48), 50% were published in 2018/2019. A majority targeted mild TBI, with equal focus on non-computerized versus computerized measures of VOR. Computerized assessment tools used were videonystagmography, dynamic visual acuity/gaze stability, rotary chair, and caloric irrigation. Non-computerized tests included the head thrust, dynamic visual acuity, gaze stability, head shaking nystagmus, rotary chair tests and the vestibular/oculomotor screening tool. High variability in administration protocols were identified. Namely: testing environment, distances/positioning/equipment used, active/passive state, procedures, rotation frequencies, and variables observed. Conclusions: There is a rapid growth of literature incorporating VOR tests in mild TBI but moderate and severe TBI continues to be under-represented. Determining how to pair a clinical test with a computerized tool and developing standardized protocols when administering tests will help in developing an optimal battery assessing the VOR in TBI. [ABSTRACT FROM AUTHOR]

This cross-sectional study included early menopausal and late menopausal women aged between 40 and 60 years to evaluate the effects of menopause on semicircular canal function. A video head impulse test (vHIT) was performed for all subjects. Vestibulo-ocular reflex (VOR) mean gains of each semicircular canal and gain asymmetry were compared between groups. Of the 87 subjects, 37(42.5%) were reproductive age 28(32.5%) were early menopausal and 22(25.3%) were late menopausal patients. VOR gain of semicircular canals or gain asymmetry values did not differ between groups. In postmenopausal women, presence of vasomotor symptoms was associated with higher gain asymmetry of the left anterior-right posterior (LARP) plane (p =.01), and presence of balance problems was associated with lower right anterior (RA) VOR gain (p =.01). In conclusion semicircular canal function in postmenopausal women was similar to that in women of reproductive age. What is already known on this subject? During menopause, women face potential risks such as dizziness, balance problems, falls and fractures. Postmenopausal patients were tested with dynamic posturography to measure balance before and after oestrogen treatment, and it was shown that balance problems significantly improved with oestrogen treatment. Healthy vestibular system is one of the components for sustaining normal balance. What do the results of this study add? In postmenopausal women the function of the semicircular canals is normal and the balance deficit in postmenopausal women may not be caused by the vestibular system. In this study changes within normal limits were observed in vestibular system of postmenopausal women. What are the implications of these findings for clinical practice and/or further research? Reported balance deficits might have been due to central origin. Further research to differentiate origin of balance deficits are needed. Specific research on symptomatic postmenopausal patients would reveal more information. [ABSTRACT FROM AUTHOR]

Animal and human studies demonstrate anatomical and functional links between the vestibular nuclei and the circadian timing system. This promotes the hypothesis of a circadian rhythm of vestibular function. The objective of this study was to evaluate the vestibular function through the vestibulo-ocular reflex using a rotatory chair at different times of the day to assess circadian rhythmicity of vestibular function. Two identical studies evaluating temporal variation of the vestibulo-ocular reflex (VOR) were performed, the first in young adults (age: 22.4 ± 1.5 y), and the second in older adults (70.7 ± 4.7 y). The slow phase velocity and time constant of the VOR were evaluated in six separate test sessions, i.e., 02:00, 06:00, 10:00, 14:00, 18:00, and 22:00 h. In both studies, markers of circadian rhythmicity (temperature, fatigue, and sleepiness) displayed expected usual temporal variation. In young adults, the time constant of the VOR showed variation throughout the day (p <.005), being maximum 12:25 h (06:00 h test session) before the acrophase of temperature circadian rhythm. In older adults, the slow phase velocity and time constant also displayed temporal variation (p <.05). Maximum values were recorded at 10:35 h (06:00 h test session) before the acrophase of temperature circadian rhythm. The present study demonstrates that vestibular function is not constant throughout the day. The implication of the temporal variation in vestibular system in equilibrium potentially exposes the elderly, in particular, to differential risk during the 24 h of losing balance and falling. [ABSTRACT FROM AUTHOR]

Introduction: We currently interpret the video Head Impulse Test (vHIT) results mainly based on the gain value. Aim: The purpose of this study is to evaluate vHIT results for both gain and re-fixation saccades on unilateral definite Meniere's disease (MD) subjects in comparison with normal healthy subjects. Materials and Methods: Forty unilateral definite MD subjects and age-matched healthy subjects were recruited. Pure tone audiometry, the caloric test, and the vHIT test were performed on MD subjects. The vHIT test was performed on healthy subjects. Results: The velocity regression gain (VRG) of the affected ear in patients with MD is significantly lower than of those in healthy subjects. The total percentage of refixation saccades is significantly higher in patients with MD when compared to healthy subjects. VRG values were not well-correlated with the percentage of refixation saccades. VRG asymmetry values are also not well-correlated with the percentage of unilateral canal weakness. A moderately stronger correlation between the percentage of refixation saccades and percentage of unilateral canal weakness, with an r2 of 0.474. Conclusions: The present study suggests that while VRGs are still a diagnostic parameter of detecting MD, the presence of refixation saccades can also have diagnostic value, especially with normal VRGs, in detecting MD. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether the use of mental tasking, when compared to no mental task, affects measurement of nystagmus response with regard to gain, phase & symmetry, and artefact when utilising video-oculography (VOG) as the measurement technique in rotary chair testing (RCT). Design: A within-subject repeated-measures design was utilised. Study samples: Seventeen (17) healthy adults were evaluated (age 22–25 years). Each participant underwent slow harmonic acceleration (SHA) testing for 0.01, 0.02, 0.04, 0.08, and 0.16 Hz using RCT at two separate counterbalanced visits. At one visit mental tasking was utilised while the other visit did not utilise mental tasking. The following outcomes were measured for each visit: gain, phase, symmetry, and artefact. Results: No significant difference between the tasking conditions with regard to gain, phase, symmetry, or artefact. Significant frequency affects were noted, as expected, for gain, phase, and artefact. Analysis of individual subject data did, however, describe significant effects of tasking with regard to gain, phase, symmetry, and artefact. Conclusion: These results suggest that the use of mental tasking during RCT using VOG had no significant group effect on SHA gain, phase, symmetry, and artefact. However, individual subject effects were observed indicating variability in the effects of mental tasking during RCT. [ABSTRACT FROM AUTHOR]

Background: Head motions cause transient vertigo in patients with benign paroxysmal positional vertigo (BPPV) and may reduce visual ability. Objectives: The aim is to investigate the clinical utility of dynamic visual acuity (DVA) test in those patients. Material and methods: Thirty patients, 11 with lateral canal BPPV (6 geotropic and 5 ageotropic), and 19 with posterior canal BPPV, were evaluated with DVA test during rapid horizontal (left and right) and vertical (up and down) head movements. Patients were asked to identify the direction of the letter C, ranging from 1.0 to 0.0 logMAR, while moving their heads. The orientation of the optotype was randomly changed by a computer-generated program. Ten subjects were served as control. Data were analyzed with a one-way ANOVA. p Value <.01 was considered significant. Results: Patients with LC and PC BPPV had significant DVA loss as compared with control subjects (p < .01). However, no significant difference was found in vDVA between patients with LC and PC BPPV, or in hDVA between ipsilesional and contralesional head rotation in patients with LC or PC BPPV (LC: p = .755, PC: p = .765). Conclusions: Patients with BPPV may have impaired visual acuity, particularly during acute onset condition. Present study indicated that DVA test was not helpful for differentiation of the pathologic and normal ears. [ABSTRACT FROM AUTHOR]

Objective: The goal of this study was to determine the sensitivity and specificity of some widely used, easily administered clinical tests. Background: Simple tests of oculomotor function have become widely used for clinical screening of patients suspected of having vestibular disorders despite a paucity of evidence showing good statistical support for their use in this highly variable population. Methods: Healthy controls with no history of otologic or neurologic disorders (n = 291) were compared to patients with known vestibular disorders (n = 62). All subjects performed passive and active head shaking, un-instrumented head impulse tests (HT), and video head impulse tests (vHIT) recorded with infrared video-oculography. Results: For both passive and active head shaking, using presence/absence of vertigo and of nystagmus, sensitivity was low (<0.40). Sensitivity of presence/absence of saccades on HT was even lower (<0.15). On vHIT, gains were all approximately = 1.0, so sensitivity was very low (approximately 0.15-0.35). Sensitivity and specificity for presence/absence of saccades were moderately poor (less than 0.70). Conclusion: None of these tests are adequate for screening patients in the out-patient clinic for vestibular disorders or for screening people in epidemiologic studies to determine the prevalence of vestibular disorders. [ABSTRACT FROM AUTHOR]

Objective: The goal of this study was to determine the sensitivity and specificity of some widely used, easily administered clinical tests. Background: Simple tests of oculomotor function have become widely used for clinical screening of patients suspected of having vestibular disorders despite a paucity of evidence showing good statistical support for their use in this highly variable population. Methods: Healthy controls with no history of otologic or neurologic disorders (n=291) were compared to patients with known vestibular disorders (n=62). All subjects performed passive and active head shaking, un-instrumented head impulse tests (HT), and video head impulse tests (vHIT) recorded with infrared video-oculography. Results: For both passive and active head shaking, using presence/absence of vertigo and of nystagmus, sensitivity was low (<0.40). Sensitivity of presence/absence of saccades on HT was even lower (<0.15). On vHIT, gains were all approximately=1.0, so sensitivity was very low (approximately 0.15-0.35). Sensitivity and specificity for presence/absence of saccades were moderately poor (less than 0.70). Conclusion: None of these tests are adequate for screening patients in the out-patient clinic for vestibular disorders or for screening people in epidemiologic studies to determine the prevalence of vestibular disorders. [ABSTRACT FROM AUTHOR]

Conclusions:The step stimulus procedure can provide information on the time course of the vestibulo-ocular reflex. Spinocerebellar degeneration and aging seem to shorten the time constant of the onset of the vestibulo-ocular reflex, causing a rapid rise up. Failure of the central processing of velocity storage might contribute to this rapid rise up. Objectives:The aim of this study is to evaluate the time course characteristics of the vestibulo-ocular reflex in patients with spinocerebellar degeneration. Methods:Ten patients (20 ears) and 22 healthy subjects (30 ears) underwent caloric test using the step stimulus procedure. We evaluated the time course of caloric VOR and calculated the parameters of the time constant of an activation and adaptation response. We compared between the control and SCD groups to elucidate the time course characteristics of caloric VOR in patients with SCD. Results:Spinocerebellar degeneration seems to shorten the time constant of the activation response by caloric irrigation with 20 °C, 7l/min air. However, aging also possibly contributes to this shortening. No change was observed in the time constant of the adaptation response. [ABSTRACT FROM PUBLISHER]

Objective: To investigate the characteristics and clinical utility of vestibular autorotation test (VAT) in patients with vestibular migraine. Methods: This study included two groups, an experimental group (441 patients) and a control group (65 healthy subjects). Both groups undertook VAT; the parameters evaluated were horizontal gain/phase, vertical gain/phase and asymmetry. The differences in VAT results between the two groups were investigated. Results: There were no statistical differences between the VAT data of the control group when compared to the reference value from the manufacturer (p >.05). There were statistically significant differences in VAT results between the experimental and control group, namely elevated horizontal gain at frequency 2, 3, 4 and 5 Hz, horizontal phase delay at frequency 2, 4, 5 and 6 Hz, elevated vertical gain at frequency 2 6Hz and vertical phase delay at frequency 4 6Hz. Conclusion: The results of this study using VAT in VM patients demonstrate elevated horizontal gain, vertical gain and delay in horizontal phase, vertical phase. We suggest the application of VAT as a diagnostic tool which may provide objective evidence that can contribute to the diagnosis of VM and also in differential diagnosis. [ABSTRACT FROM AUTHOR]

Conclusion: Ocular vestibular evoked myogenic potentials (oVEMPs) to binaural air-conducted stimulation (ACS) may provide a convenient way of assessing the crossed vestibulo-ocular reflex in patients with vestibular dysfunction as well as in healthy subjects. Objective: To investigate the clinical feasibility of using oVEMPs in response to binaural ACS to assess normal subjects and patients with vestibular dysfunction. Methods: The study investigated 24 normal subjects (14 men and 10 women, aged from 23 to 60 years) and 14 patients with unilateral peripheral vestibular dysfunction. Each subject underwent oVEMP testing in response to monaural ACS and binaural ACS (500 Hz tone burst, 135 dBSPL). Results: In normal subjects, bilateral oVEMPs were elicited in 75% of subjects in response to monaural ACS and in 91% in response to binaural ACS. Asymmetry ratios (ARs) of the responses to binaural ACS were significantly smaller than those of the responses to monaural ACS ( p < 0.01). In patients with unilateral vestibular dysfunction, there were no significant differences in the amplitude, latency, or AR of the responses between monaural and binaural ACS. Approximately 30% of patients showed reduced ARs to binaural ACS relative to monaural ACS, primarily due to contamination by uncrossed responses elicited in healthy ears. [ABSTRACT FROM AUTHOR]

Keywords: Vestibular; neuroimaging; autonomic; sensorimotor; intervention EN Vestibular neuroimaging autonomic sensorimotor intervention 421 422 2 12/01/20 20201001 NES 201001 Ferrè and Haggard (this issue) provide a conceptual framework for understanding vestibular cognition, and articulate a clear research programme to substantially advance this field. Historically, the vestibular system has been studied through the lens of subcortical brainstem-mediated vestibular reflexes such as the vestibulo-ocular reflex. Ferrè and Haggard note that the "tentacular" projections of the vestibular system throughout the cortex and subcortex indicate a "pervasive, modulatory" influence of the vestibular system on cognitive processes. [Extracted from the article]

Conclusion: The age-related changes in ocular vestibular-evoked myogenic potentials (oVEMPs) elicited by galvanic vestibular stimulation (GVS) and bone-conducted vibration (BCV) might be attributed to the morphological degeneration of the vestibular system. Objective: This study employed GVS and BCV modes for eliciting oVEMPs in healthy subjects to explore the effect of aging on the vestibulo-ocular reflex (VOR) pathway. Methods: Sixty-nine healthy subjects (aged 22-69 years) were divided into 5 groups of 12-19 subjects by decades of age. All subjects underwent oVEMPs using GVS and BCV modes. The prevalence and parameters of oVEMPs, including nI latency, pI latency, nI-pI interval, and nI-pI amplitude were measured and compared. Results: The prevalences of GVS-oVEMPs had nonsignificant differences among all age groups, whereas that of BCV-oVEMPs in the over-60 group was significantly lower than those in the under-60 groups. In GVS-oVEMPs, the group over 60 years had significantly longer nI, pI latencies, and smaller amplitudes when compared with those under 60 years. In BCV-oVEMPs, the nI and pI latencies in the over-60 group were significantly longer than those of the under-60 groups, while the nI-pI amplitudes of groups over 50 years were significantly smaller than those of groups under 50 years. All oVEMP parameters exhibited significant differences between GVS- and BCV-oVEMPs in each age group. [ABSTRACT FROM AUTHOR]

Conclusions: These findings are in line with previous data on the horizontal vestibulo-ocular reflex (VOR) from this laboratory and suggest that eye position signals do not modulate natural vestibular responses. Hence, the Alexander's law (AL) phenomenon cannot be interpreted simply as a consequence of vestibular or oculomotor nuclei activity modulation with desired gaze. Background: AL states that the intensity of the spontaneous nystagmus of a patient with a unilateral vestibular lesion grows with increasing gaze in the direction of the fast phase. Some of the mechanisms proposed to account for the gaze effects assume a direct modification of the normal VOR by eye position signals. We tested the validity of these assumptions and investigated the effects of gaze direction on the normal vertical human VOR in the behaviorally relevant high frequency range. Methods: Head and eye movements were recorded with the search coil method during passive head impulses in pitch, while subjects were asked to hold gaze at various elevation angles in 8° steps within ± 16° from the straight ahead reference position. Results: Upward and downward head rotations produced VOR gains of similar magnitude. Furthermore, the gain remained unaffected by eye-in-orbit position for both upward and downward head impulses. [ABSTRACT FROM AUTHOR]

In 2 experiments, we evaluated relations between postural activity and the amplitude of visually guided eye movements. Participants shifted their gaze to follow horizontal oscillation of a visible target. The target moved with amplitude 9° or 24°. In different experiments, the frequency of target oscillation was 0.5 Hz or 1.1 Hz. In both experiments, the variability of head and torso motion was reduced (in the anterior-posterior axis) when participants viewed moving targets, relative to sway during viewing of stationary targets. Sway variability was not influenced by the amplitude of target motion. The results are compatible with the hypothesis that postural activity was modulated relative to the demands of suprapostural visual tasks. [ABSTRACT FROM PUBLISHER]

Conclusions: Dynamic visual acuity (DVA) during the head-thrust test (htDVA) is reliable in normal subjects, having a high specificity for the horizontal canal, so it may be useful to monitor vestibular rehabilitation in patients with vestibular neuritis (VN). Objective: To obtain reference values for htDVA in healthy individuals and to investigate the potential application in subjects with unilateral VN. Methods: A total of 73 healthy individuals and 50 patients with unilateral VN were included. The DVA test was performed by adjusting a sensor on the subject's head to measure head velocity. During head thrust, the optotype flashed if the head velocity reached 150°/s, as previously defined, and a DVA score was obtained for each canal. Results: The htDVA was reliable in normal subjects (intra-class correlation coefficient (ICC) = 0.44-0.71; p = 0.001-0.007). The htDVA score showed an age-dependent increase for all canals ( p < 0.0001). The 95th percentile of htDVA was used as the criterion to consider htDVA as abnormal in patients with VN. In all, 44%, 30%, and 16% of patients had an increase in htDVA score for one, two or all three canals on the affected side. The sensitivity and specificity of the htDVA test for the horizontal canal were 22% and 85%, respectively. [ABSTRACT FROM AUTHOR]

Abstract This study analysed the acoustic and vestibular functional and morphological modifications in guinea pigs after acoustic trauma. Animals were exposed to noise (6 kHz, at 120 dB SPL for 60 minutes) and then auditory brainstem responses (ABR) and vestibuloocular reflex (VOR) were measured at 6 hours, 1 day, 3, 7, and 21 days after noise. Western blotting and immunostaining for 4-hydroxy-2-noneal (4-HNE) and vascular endothelial growth factor (VEGF) were performed in the cochlear and vestibular regions at 1 and 7 days after noise exposure. A significant decrease of VOR gain was observed on day 1 and the recovery was completed at day 21. ABR threshold values reached a level of 80 dB at day 1 after trauma reaching a value of about 50 dB SPL on day 21. 4-HNE expression, a marker of lipid peroxidation was strongly increased in the cochlea. In the vestibule, 4-HNE immunoreactivity was faint. However, VEGF was up-regulated both in the cochlea and vestibule. In conclusion, the expression of VEGF in both cochlear and vestibular structures suggests a reparative role with potentially therapeutic implications. Sumario Este estudio analiza las modificaciones vestibulares funcionales y morfológicas en los cobayos después de un trauma acústico. Los animales fueron expuestos a ruido (6kHz, a 120dB SPL durante 60 minutos) y se midieron las respuestas auditivas de tallo cerebral (ABR) y el reflejo vestíbulo-ocular (VOR); a las 6 horas, al siguiente día y los días 3, 7 y 21 después del ruido. Se realizaron pruebas de Western Blot e inmuno-reacciones para 4-hydroxi-2-noneal (4-HNE) y para factor de crecimiento vascular endotelial (VEGF) en las regiones coclear y vestibu-lar en los días 1 y 7 después de la exposición a ruido. Los resultados mostraron un descenso significativo de la ganancia del VOR en el día 1 y la recuperación fue completa en el día 21. Los umbrales de ABR llegaron a un nivel de 80dB en el día 1 después del trauma, alcanzando un valor de 50dB SPL en el día 21. El marcador 4-HNE, indicativo de peroxidación de los lípidos, estaba bastante aumentado en la cóclea. En la región vestibular, la reacción 4-HNE fue débil. Sin embargo, el VEGF se reguló por incremento tanto en la cóclea como en el vestíbulo. En conclusión, la expresión del VEGF en las estructuras tanto cocleares como vestibulares sugiere un papel reparador con potenciales implicaciones terapéuticas. [ABSTRACT FROM AUTHOR]

Conclusions: The caloric test with head-tilt can be used as a tool for assessing vertical canal function as an office procedure. Objective: Evaluation of vertical canal function. Patients and methods: We provoked caloric response by cold water in the vertiginous patients in supine position. During the culmination of the response we rotated the head 45° from the sagittal plane to place the posterior canal to earth-vertical. Thereafter we rotated the head 45° to the opposite direction to place the anterior canal to earth-vertical. The eye movements were recorded by two-dimensional electronystagmography. The data collected from the examination of 100 ears with normal caloric response in horizontal component were analyzed. Results: The down-beating vertical component intensified when the posterior canal was placed to earth-vertical. The up-beating vertical component intensified when the anterior canal was placed to earth-vertical. These findings suggested that the vertical canals were functioning. [ABSTRACT FROM AUTHOR]

Conclusion. The pitch plane vestibulo-ocular reflex (VOR) gain and symmetry at low frequencies (≤0.3 Hz) are enhanced by otoliths and/or somatosensory sensory cues during combined angular and linear stimuli. We conclude that neural processing of these linear motion cues is used to improve the VOR when stimulus frequencies are below the optimal range for the canals. Objective. The purpose of this study was to examine the effects of eccentric rotation on the passive pitch VOR responses in humans. Subjects and methods. Eleven subjects were placed on their left sides (90° roll position) and rotated in the pitch plane about an earth-vertical axis at 0.13, 0.3, and 0.56 Hz. The inter-aural axis was either aligned with the axis of rotation (no modulation of linear acceleration) or offset from it by 50 cm (centripetal linear acceleration directed feet-ward). The modulation of pitch VOR responses was measured in the dark with a binocular videography system. Results. The pitch VOR gain was significantly increased and the VOR asymmetry was significantly reduced at the lowest stimulus frequencies during eccentric rotation. There was no effect of eccentric rotation on the pitch gain or asymmetry at the highest frequency tested. [ABSTRACT FROM AUTHOR]

Introduction: Latest measurements of the vestibulo-ocular reflex (VOR) allowed the integration of the simulation of the Bielschowsky head-tilt test (BHTT) into the SEE++ software system. SEE++ realizes a biomechanical model of the human eye in order to simulate eye motility disorders and strabismus surgeries. With the addition of the BHTT it can now also be used for differential-diagnostic simulations of complex disorders (e.g., superior oblique palsies). Methods: In order to simulate the BHTT in SEE++, the user can freely choose the desired head-tilt angle from -45° to +45°. The chosen angle is shown in the 3D view with a human body model and is also used in the calculation of the Hess-Lancaster test. Results: The integration of the BHTT offers an additional improvement of the possibilities for simulating eye motility disorders. Moreover, SEE++ allows the creation of a video of the “virtual patient” while tilting the head from one side to the other, which shows dynamic changes in the simulated Hess-diagrams. Discussion: Comparisons of simulation results with patient-measured data showed a good correlation between the simulated and the measured data. Further comparisons with patient data are planned. [ABSTRACT FROM AUTHOR]

Conclusion. Motorized head impulse rotator is an effective technique to assess peripheral vestibular function. Approximately a quarter of patients with vestibular schwannoma (VS) had preserved preoperative responses. Vestibular disability could not be predicted based on vestibulo-ocular reflex (VOR) performance during motion stimuli, or in the caloric test. Objectives. To explore motorized head impulse rotator for evaluation of angular horizontal VOR in patients with VS, and to compare these responses to those of the caloric test and the symptoms. Patients and methods. We prospectively recorded head and eye position during unpredictable motorized head impulses in 38 patients with VS. We calculated gain and asymmetry of VOR (mean±95% CI), and the results were compared to those of the caloric test and a questionnaire regarding dizziness, hearing and quality of life. Results. The VOR during motorized impulses was abnormal in 71% of patients. Asymmetry in gain correlated significantly (p<0.001) with unilateral weakness in the caloric test. Preoperative gain was significantly lowered to 0.83±0.08 on the ipsilateral side compared to 0.98±0.06 on the contralateral side. Postoperative gain on the operated side of 0.53±0.05 was significantly different from preoperative gain (p<0.001). Findings in vestibular tests did not correlate with subjective sensation of dizziness. [ABSTRACT FROM AUTHOR]

Conclusion. The skull vibration-induced nystagmus test (SVINT) is a useful complementary test to the caloric test, which evaluates very low frequencies, and the head shaking test (HST), which explores medium range frequencies. These three tests are fully correlated in total unilateral vestibular lesions (tUVL) with a sensitivity of 98% and a specificity of 94% for the SVINT. The results of the interference of the SVINT with the cold caloric test on the intact ear suggest that different vestibular sensory cells are involved in these two tests. The stimulus location optimization suggests that vibrations directly stimulate the inner ear on the intact side. Objectives. The aim of this study was to establish the effectiveness of a rapid, non-invasive test used to detect vestibular asymmetry at 30, 60 and 100 Hz stimulation in tUVL. Patients and methods. The high frequency vibration test applied to the skull using the SVINT was compared to the results of HST and caloric test in 134 patients and 95 normal subjects: 131 patients had a total unilateral vestibular dysfunction and 3 had a bilateral total lesion (tBVL). The effects of stimulus frequency, topography and head position were studied using a video-nystagmograph. Results. In tUVL, the SVINT always revealed a lesional nystagmus beating toward the healthy side at all frequencies. The mastoid site was more efficient than the cervical and vertex sites (p<0.005). The mean skull vibratory nystagmus (SVN) slow phase velocity (SPV) is 10.7°/s (SD =7.5; n=20). Mastoid stimulation efficiency was not correlated with the side of stimulation. SVN SPV was correlated with the total caloric efficiency on the healthy ear (p=0.03). The interference of the SVINT during the cold caloric test on the intact ear demonstrated a reversal of the caloric nystagmus at each application of the vibrator. In tBVL, SVINT revealed no nystagmus. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Conclusions. The Dutch (Belgium) translation of the Dizziness Handicap Inventory (DHI) has proven to be as consistent as the original version. In addition to the three original subscales, factor analysis revealed a fourth component scoring self-perceived effects of insufficient functioning of the vestibulo-ocular reflex (VOR). Focus should be on the DHI total score in order to compare future results with the existing literature. Objective. To conduct a factor analysis and to determine its internal consistency. Materials and methods. Charts of 214 outpatients, referred with dizziness or imbalance of vestibular and non-vestibular origin, were reviewed. Results. The Cronbach's alpha coefficients for internal consistency were high for the total scale and good for the subscales. Corrected item-total correlations ranged from 0.71 for 'restricted travelling' to 0.29 for 'difficulties reading', when items were correlated with their respective subtotals, and ranged from 0.69 (restricted participation in social activities) to 0.33 (stressed relationships), when correlated with the total score. A principal component analysis with orthogonal rotation was conducted, suggesting a four-factor solution. Two factors were related to vestibular handicap, referring to the original functional and emotional subcategories. The remaining two factors related to vestibular disability, documenting motion sensitivity (original physical subscale) and insufficient VOR functioning. [ABSTRACT FROM AUTHOR]

Conclusion. These data suggest that visual acuity during quiet sitting is dynamic, requiring full body interaction of vestibulo-ocular and postural responses. These findings may have practical implications for seating design and design of tasks requiring good visual acuity while seated. Objectives. Looking at something during quiet sitting is usually assumed to be a static activity. We tested the idea that visual acuity during quiet sitting is dynamic, requiring integration of whole body responses as well as intact vestibulo-ocular reflexes. Materials and methods. Normal subjects and patients scheduled for acoustic neuroma resection were tested preoperatively. Patients were then tested during the four in-patient postoperative days. Testing was done while seated, with or without head and back support, while reading numbers from slides on a laptop computer at eye level, in font sizes from 20pt to 12pt. The dependent measure was percent correct per font size. Results. In both groups scores while sitting unsupported were significantly higher than with full support or only back support. In patients, scores were significantly decreased on postoperative day 1 and gradually increased toward normal but maintained the pattern of better scores when sitting unsupported than with head or back support. [ABSTRACT FROM AUTHOR]

Conclusions. We recommend performing the test for nystagmus actively, both when the response is analyzed at bedside or with videonystagmography. If no nystagmus is observed with the active test, it should then be performed passively. Objective. Head-shaking nystagmus (HSN) is a sign of vestibular dysfunction that is elicited after actively (patient) or passively (examiner) shaking a patient's head. The objective of this study was to analyze the frequency of HSN when the test is performed actively (aHSN) or passively (pHSN), and to determine whether any differences in the results might be due to age or disease state, or whether they reflect the results of different vestibular tests. Patients and methods. This was a prospective study conducted at a tertiary care center. The head-shaking test was carried out actively and passively on 100 patients. The caloric test, the rotatory chair tests and the measures of disability were performed on the same day and in the same setting. HSN was considered to be present when it was seen for a period longer than 5 s or if the maximum slow-phase velocity of HSN was higher than 3°s-1. Four groups were established according to the results of the two testing methods. Results. The frequency of aHSN was 47% and of pHSN was 46% when the presence of nystagmus was established as the criterion. Moreover, in patients who had experienced vestibular neuritis previously, the type of nystagmus was age-dependent. When the velocity of the nystagmus elicited was considered, the results coincided with the method of testing in 74% of the patients, while they differed in 26% of subjects; the aforementioned age dependency was no longer seen. Differences in the caloric and rotatory chair test results, as well as in disability, were observed in the groups generated on the basis of the types of nystagmus. [ABSTRACT FROM AUTHOR]

Conclusions. Gentamicin ototoxicity presents with gait imbalance and oscillopsia, but only rarely with hearing loss and vertigo. Sinusoidal rotational stimuli with high accelerations such as the bedside head-thrust test or rotational step changes in velocity are useful to diagnose bilateral vestibulopathy. Objective. To describe the salient clinical features and vestibular testing results in gentamicin ototoxicity. Patients and methods. A retrospective review of the quantitative vestibular function testing results for patients presenting to the UCLA Neurotology Clinic with gentamicin ototoxicity over the past 10 years ( n =35). Results. All patients presented with imbalance and 33 out of 35 had oscillopsia. Three patients reported a noticeable change in hearing and five reported vertigo. Of the 35 patients, 15 were in renal failure at the time of gentamicin administration. Patients with pre-existing peripheral neuropathy compensated poorly. Sinusoidal rotational testing demonstrated profoundly decreased gain and increased phase lead over the entire frequency range, with a subset of patients having relatively preserved gain at the intermediate frequencies (0.8–1.6 Hz) and low acceleration ( <30°/s). There was little or no response to high acceleration step changes in velocity. The time constant measured both by sinusoidal and step responses was ultra-low. All patients tested had a positive head-thrust test bilaterally. [ABSTRACT FROM AUTHOR]

Conclusions. Subjective visual vertical (SVV) estimation during on-axis rotation provides an efficient screening test of utricle function. The survey demonstrates that isolated disorders of peripheral utricular function can occur while SCC function appears normal. Objective. The present study aimed to investigate estimation of SVV during constant velocity yaw rotation (with the head held on-axis – to enhance any asymmetry between right and left utricular responses), as a useful screening test. Materials and methods. In all, 230 patients were recruited from the dizziness clinic. For each patient, the SVV was estimated (a) while held stationary, and (b) during constant angular velocity (240°/s), with the head centred on-axis. Bithermal caloric testing was also performed in 201 of the patients. Results. Of those patients with normal SVV results during stationary testing, 18.3% were pathological during rotation testing. In those cases with pathological SVV during stationary testing, a significantly greater deviation from the norm was observed during rotation ( p <0.001). Of those patients with normal caloric responses, 44.4% showed pathological SVV estimates; this increased to 54.3% for cases with unilateral weakness, and 56.5% for unilateral loss. No clear correlation was found between reports of tilt illusion and pathological SVV, respectively, between rotatory vertigo and pathological caloric responses. [ABSTRACT FROM AUTHOR]

Conclusions. When considering benign recurrent vertigo and a similar peripheral vestibular deficiency, the asymmetry of the vestibulo-ocular reflex (VOR) time constant (Tc) is lower in those patients with paretic head-shaking nystagmus (HSN) than in those with reversed HSN or without HSN. Objective: To determine whether the existence of HSN is related to the time constant of the VOR in patients with benign recurrent vertigo (BRV). Patients and methods. This was a prospective study conducted at a tertiary care center in which patients were subjected to the head-shaking test, the caloric test and rotatory chair impulsive test on the same day. The clinical features of the disease analyzed were the disease duration, frequency of vertigo spells, time since the last vertigo spell and the existence of migraine. The results of the head-shaking test were considered positive when nystagmus appeared after head-shaking had ended. Two groups of patients were established on the basis of these results and the group that displayed HSN was divided according to the direction of nystagmus. In the impulsive test, the time constant of the VOR after ipsilesional and contralesional acceleration was analyzed, as was the symmetry of the response. The differences in the means were calculated. Results: BRV was diagnosed in 25% of patients suffering recurrent spells of vertigo, of which 33 patients were HSN- and 29 were HSN+. In the latter group, vestibular migraine was frequently observed (83% of the patients), the spells of vertigo were more frequent and the patients were seen closer to the previous spell of vertigo. No differences were observed in the Tc of the VOR between HSN+ and HSN- patients, although the asymmetry of this Tc was higher in HSN- patients than in HSN+ patients. Nevertheless, the differences observed were only significant between paretic and reversed HSN patients and paretic HSN patients and HSN- patients. [ABSTRACT FROM AUTHOR]

Conclusions. Although vestibular recovery was observed after steroid treatment, it remains uncertain whether this improvement was spontaneous or due to medication. These data do not allow us to generally recommend corticosteroid treatment in patients with BVF and inner ear antibodies. Objective. A retrospective study was performed based on the observation of two patients with suspected autoimmune bilateral vestibular failure (BVF) with normal hearing and antilabyrinthine or nervous tissue-specific serum antibodies who showed vestibular recovery after corticosteroid treatment. Material and methods. Twelve patients with BVF and serum inner ear antibodies who had received imuunosuppressive treatment with corticosteroids were evaluated in terms of medical history, repetitive caloric irrigation and repetitive determination of inner ear antibodies. BVF was complete in four patients and incomplete in eight. Results. After immunosuppressive therapy, four of the 12 patients showed a moderate recovery of the peak slow-phase velocity of horizontal nystagmus induced by bithermal caloric stimulation, which was only transient in two of them. [ABSTRACT FROM AUTHOR]

Conclusions. Our findings suggest that canal function is substantially preserved in subjects with active vertigo attacks as a result of Ménière's disease (MD). In these subjects, the head-thrust test (HTT) may not be as sensitive to canal dysfunction as traditional caloric testing. MD may differentially affect the low-frequency sensitivity of the canals. Objective. Caloric tests have traditionally been used to characterize semicircular canal function in vestibular disorders, including MD. The quantitative HTT provides an objective measurement of semicircular canal function in the frequency and velocity ranges of normal head movements. The aim of this study was to compare the findings of caloric and HTTs in subjects with unilateral MD. Material and methods. The study population consisted of 38 candidates for gentamicin treatment due to a high frequency of vertiginous attacks (25 males, 13 females; mean age 52.9 years; range 30–70 years). The duration of symptoms was 1–30 years (mean 5.3 years). Horizontal canal function was characterized with bithermal aqueous caloric tests and recordings of the angular vestibulo-ocular reflexes (aVORs) using the scleral search-coil technique during HTTs. The main outcomes were unilateral weakness (UW) on caloric testing and aVOR gain asymmetry (GA) during HTTs. A caloric response asymmetry of >20% was considered to be indicative of pathologic UW. A difference in GA during HTTs of >5.8% was considered significant. Results. Twenty subjects (52.6%) showed abnormal results on one or both tests. Pathologic UW was present in 16 subjects (42.1%). During HTTs, 11 subjects (28.9%) showed pathologic GA. Seven subjects (18.4%) showed abnormal results on both tests. A significant correlation was found between UW and GA. However, pathologic GA during HTTs in subjects with unilateral MD was less frequent and the values smaller than those published for vestibular neuritis patients. Two subjects with unilateral MD had 100% UW, but none had >30% asymmetry on HTTs. [ABSTRACT FROM AUTHOR]

Conclusion Saccular and utricular maculae can provide information on the supine static position, considering that both have pronounced curved structures with hair cells having a variety of polarization vectors that enable them to sense an inverted position and thus direct the righting reflex. Objective The vestibular system is essential for the structuring of motor behaviour, senses linear and angular acceleration and has a strong influence on posture and balance at rest, during locomotion and in head–body righting reflexes. Material and methods Using guinea pigs in the supine position with a symmetrical head and trunk position, the ocular position was analysed to ascertain whether any ocular movement that occurred would adopt a spatial deviation indicative of the subsequent head and body righting. The characteristics of the righting reflex (direction, latency, duration and velocity) were analysed in guinea pigs from position signals obtained from search coils implanted in the eye, head and pelvis. The animals were kept in a supine position for a few seconds or even minutes with the eyes in a stable primary position and the head and body symmetrical and immobile. Results The righting reflex took place either immediately or after a slow deviation of the eyes. In both cases the righting sequence (eyes, head, body) was stereotyped and consistent. The direction of head and body righting was along the longitudinal axis of the animal and was either clockwise or anticlockwise and the direction of righting was related to the direction of the eye deviation. The ocular deviation and the direction of deviation that initiated and determined the direction of the righting reflex could be explained by possible otolithic activation. [ABSTRACT FROM AUTHOR]

A 56-year-old man receiving treatment for hypertension experienced sudden-onset dizziness and was admitted to our hospital. Computed tomography of the brain revealed a small high-density lesion in the right rostral midbrain. Subsequent magnetic resonance imaging revealed a small hemorrhagic lesion in the same position. The patient complained of double vision affecting the right side when viewing a horizontal linear target. Vergence was intact, but vertical gaze was severely restricted downward and moderately restricted upward. Vestibulo-ocular reflex maneuvers did not alleviate the patient's vertical gaze palsy. By 40 days after the incident, his motility had recovered and he could begin to tilt his head to the left. Consecutive Hess tests demonstrated a skew deviation of right hypertropia, which continued for over two years. Funduscopic examination revealed left extorsion but no right intorsion. A diagnosis of posterior canal-type ocular tilt reaction (OTR) was made from these signs. The patient's course indicated that periaqueductal syndrome dominated in the acute stage whilst unilateral symptoms became more apparent in the chronic stage. The rostral interstitial nucleus of the medial longitudinal fasciculus and the posterior commissure were estimated to contain the main causative lesion for the acute symptoms, whereas the interstitial nucleus of Cajal (INC) was implicated in the chronic stage. Posterior canal-type OTR caused by unilateral INC lesion has been reported only rarely. [ABSTRACT FROM AUTHOR]

We studied a young woman with multiple sclerosis, who developed periodic alternating nystagmus (PAN) with a period of oscillation of about three minutes. Neither visual fixation of a stationary target nor large-field optokinetic stimulation substantially influenced the cycle of PAN. During convergence, induced by fixation of a near target, PAN was suppressed by over 70%. Treatment with baclofen abolished her nystagmus, but optokinetic and pursuit responses remained impaired. Convergence during viewing a near target did not increase the response (gain) of her vestibulo-ocular reflex. We postulate that visual drives were able to suppress PAN independently of any effects on vestibular responses and were prevented from exerting effects on velocity storage and vestibular gain adjustment by demyelinating lesions affecting her pontine nuclei and cerebellar circuits. [ABSTRACT FROM AUTHOR]

Objective To compare the incidence of head-shaking nystagmus (HSN) with the value of canal paresis (CP) obtained from a caloric test and to propose the optimal value of CP that can be predicted by the presence of HSN. Material and Methods HSN and caloric tests, together with other vestibular tests, were performed in 132 dizzy patients. HSN was recorded using electronystagmography with Frenzel's glasses. Results HSN was observed in 61/132 patients (46%). The sensitivity and specificity of the HSN test regarding the prediction of CP>20% were 66% and 77%, respectively. CP values were significantly higher in patients with than without HSN. Both the sensitivity and specificity of HSN were reasonably high when the limiting value of CP was set between 20% and 30%. Conclusion The limiting value of CP that discriminates the presence of HSN may be ≈20%. At this CP value, HSN shows an appropriately high sensitivity and specificity. The HSN test is not very sensitive but is still acceptable as one of the screening tests for detecting asymmetrical vestibular dysfunction. [ABSTRACT FROM AUTHOR]

Objective Several studies have shown that spatiotemporal aspects of motion are stored and can be retrieved with the use of vestibular and somatosensory cues. The purpose of this study was to examine whether intentional imagination of body rotation can induce oculomotor activity similar to the typical vestibulo-ocular reflex (VOR). Material and Methods Normal subjects without known vestibular and/or oculometric abnormalities were instructed to imagine a sensation of accelerating body rotation in the horizontal plane (rightward or leftward) while sitting in darkness with closed eyes, using only vestibular and somatosensory cues and not imaginary visual cues. Eye movements were recorded during the imagery session and also during a full, routine electronystagmography (ENG) test. All subjects selected for this study showed normal results in the ENG test, and none of them had gaze-evoked or end-point nystagmus. Results In response to imaginary rotations, horizontal eye movements were found in 91/121 recordings (75%) in 10 subjects. A typical pattern of nystagmus (0.3-3 Hz, 3-30°/s maximal speed of slow component) was recorded in 53% of mental rightward rotations and 49% of leftward rotations. The fast component was always in the direction of the imaginary rotation (similar to a normal VOR). Other types of eye movement comprised either contralateral eye drift (≈17% of trials) or macro square waves. In 25% of the recordings no definite eye movements could be detected during the mental maneuvers. Conclusion These mentally induced eye movements seem to be due to a cortical process which can affect the normal input to the brainstem nuclei. A possible mechanism is discussed. This phenomenon may serve as an objective measurement of mental activity, may be used for testing the cognitive resources of patients and can probably be used for enhancing the rehabilitation process after acute vestibular insult. [ABSTRACT FROM AUTHOR]

A number of studies have shown that cisplatin and gentamicin ototoxic effects may result from free radical-mediated damage due to the reduction of antioxidant substances and an increased lipid peroxidation. The authors summarize the results obtained evaluating the auditory and vestibular functions and the inner ear hair cell morphology and survival after administration of antioxidant agents against cisplatin and gentamicin. In the first experiment, albino guinea pigs were treated with gentamicin (100 mg/kg per day, i.m.) alone or gentamicin (100 mg/kg per day, i.m.) plus α-tocopherol (100 mg/kg per day, i.m.) for 2 weeks. In a second experiment, albino guinea pigs were injected with cisplatin (2.5 mg/kg per day) or cisplatin (2.5 mg/kg per day) plus tiopronin (300 mg/kg) for 6 days. Electrocochleographic recordings were made from an implanted round window electrode. In all experiments compound action potentials (CAPs) were measured at 2-16 kHz. Changes in cochlear function were characterized as CAP threshold shifts. To evaluate vestibular function, the animals underwent sinusoidal oscillations in the dark about their vertical and longitudinal axes to evoke horizontal and vertical vestibulo-ocular reflexes (VOR). Frequency stimulation parameters ranged from 0.02 to 0.4 Hz and peak-to-peak amplitude was 20°. Morphological changes were analysed by light microscopy and scanning electron microscopy. Both hearing loss and vestibular dysfunction induced by gentamicin were significantly attenuated by α-tocopherol. However, tiopronin co-therapy slowed the progression of hearing loss in cisplatin-treated animals and significantly attenuated the final threshold shifts. Cisplatin had little effect on the hair cells of cristae ampullares and maculae. Vestibular function was completely preserved in tiopronin co-treated animals. In conclusion, antioxidants such as α-tocopherol or tiopronin interfere with gentamicin and cisplatin damage and this suggests that they may be useful in preventing oto-vestibulotoxicity. Therefore, it is important to develop protective strategies that permit the avoidance of the toxic side effects of these drugs without interfering with their therapeutic effects. [ABSTRACT FROM AUTHOR]

Objective --To evaluate the dynamic properties of the horizontal vestibulo-ocular reflex (h-VOR) in the acute stage of two common labyrinthine diseases that provoke severe attacks of vertigo with spontaneous nystagmus: vestibular neuritis (vestibular loss alone) and viral labyrinthitis (cochleovestibular loss). Material and Methods --Sixty-three patients were investigated: 42 were diagnosed with vestibular neuritis and 21 with viral labyrinthitis. The h-VOR function was evaluated by conventional caloric and impulsive testing. A simplified model of vestibular function was used to analyze the vestibulo-ocular response to rotational stimulation. Results --The results showed a significant difference in h-VOR characteristics between the two pathologies. Patients with vestibular neuritis exhibited a strong horizontal semicircular canal deficit, but no h-VOR asymmetry between the two rotational directions. In contrast, patients with viral labyrinthitis demonstrated moderate canal paresis and a marked h-VOR deficit in rotation toward the affected ear. Conclusion --These findings support the hypothesis that the h-VOR dynamic asymmetry that occurs after an acute unilateral inner ear lesion is not due to canal dysfunction alone, but involves complex adaptive changes in the central VOR that may implicate the otolith system. Based on histopathologic and clinical differences in the two pathologies reported in the literature, we postulate that this otolith-canal interaction is mainly linked to the loss of saccular function. [ABSTRACT FROM AUTHOR]

Objective-Sinusoidal vestibular stimulation in the horizontal plane induces periodic eye instability in the intact rabbit and the hypothesis of an intrinsically unstable velocity storage mechanism has been conceived. The present research examined the stability of the vestibulo-ocular reflex (VOR) in the vertical plane, considering that the time constant values of vertical and horizontal VORs differ and that separate regions of the vestibulo-cerebellum affect the horizontal and vertical slow VOR components differently. Material and Methods-Normal pigmented rabbits were sinusoidally oscillated in the dark about their vertical and longitudinal axes to evoke horizontal and vertical eye responses. Results-Frequency and peak-to-peak amplitude stimulation parameters ranged from 0.1 to 0.8 Hz and from 5° to 20°, respectively. During horizontal VOR, periodic alternating drift (PAD) was superimposed on the ocular response, and both peak velocity and period were directly correlated with stimulation amplitude. Vestibular stimulation in the vertical plane induced PAD: the period of vertical PAD was shorter and the amplitude smaller than the corresponding horizontal PAD values. A further difference in vertical PAD occurred in the lack of modulation of period and peak velocity by the stimulus amplitude. Conclusion-These results support the hypothesis of different instabilities of the velocity storage mechanism in the vertical and horizontal planes, possibly due to separate sensory-motor systems sub-serving the vertical and horizontal VORs. [ABSTRACT FROM AUTHOR]

In order to determine which variables influence recovery from acoustic neuroma resection, acutely postoperative patients were divided into two groups and treated twice daily at bedside as inpatients at a tertiary care center. Treatment times were increased gradually from 5 to 30 min. Exercise subjects underwent passive and active head movements and walking with augmented head movements. Control subjects received attention without exercise. Pre- and post-tests included vertigo intensity and frequency, low-frequency vestibulo-ocular reflex (VOR), posturography and path integration. Post-tests were given at discharge and at ≈4-week intervals for 3 months. Multilevel statistical analyses showed that neither group assignment nor age affected the outcome. All measures were abnormal at discharge but improved towards normal within 3 weeks. VOR on the unoperated side returned to normal values but on the lesioned side did not. Therefore, compensation is influenced by tumor size but not by age or early postoperative vestibular rehabilitation. Most compensation occurs within 3 weeks, probably due to central mechanisms, although some measures may not recover completely. [ABSTRACT FROM AUTHOR]

The objective of the current study was to develop a computer-controlled mechanical system for the generation of impulsive head rotations to measure eye movements induced by angular horizontal vestibulo-ocular reflex. This is a clinical eye movement test recently introduced for the usage of otoneurological balance laboratories. We built the system and modified our prior computer software developed for other types of eye movement tests. Motor controlled stimulation has fulfilled the requirement of more uniform and constant acceleration stimulation than obtained with manually administrated impulses. After having executed preliminary experiments at our balance laboratory we found the system to be efficient, reliable and secure. [ABSTRACT FROM AUTHOR]

We compared the results of analysis of vestibulo-ocular reflex (VOR) obtained by manual rotation in routine vestibular clinical practice with that of caloric testing, and examined the validity and limitations of VOR analysis as a test for the estimation of peripheral vestibular function and imbalance. VOR response was recorded in daily vestibular clinical examinations by manually rotating the standard clinical chair for ≈ 30 s. VOR gain was slightly, but significantly, correlated with the peak slow phase velocity of caloric response (r = 0.50, p < 0.001). However, 8 out of 12 patients with no caloric response failed to exceed the range of two standard deviations of the mean value of age-matched normal subjects, indicating that it is clinically difficult to use VOR gain alone as a estimate of unilateral vestibular function. VOR directional preponderance (VOR DP%) correlated well with caloric canal paresis (CP) (CP%; r = 0.89, p < 0.001). VOR DP% was within the normal range in patients with caloric CP% < 40 and exceeded the normal range in most cases with caloric CP% > 80. VOR DP% varied widely when caloric CP% ranged between 40 and 80. The effect of vestibular compensation on VOR DP% was examined by plotting VOR DP% divided by caloric CP% (DP CP) against the number of days since the onset of vertigo in patients with vestibular neuritis or sudden deafness with vertigo. DP CP was large within 50 days of the onset of vestibular damage, especially when caloric CP% was < 80, and gradually decreased with time. These results indicate that determination of VOR DP% should contribute to the early diagnosis of fresh vestibular imbalance, especially in daily clinical practice, because this type of VOR recording can be performed in < 1 min in routine vestibular clinics. The decay time constant of DP CP was larger when caloric CP% exceeded 80, indicating that vestibular compensation proceeds more slowly when the vestibular damage is severe. [ABSTRACT FROM AUTHOR]

A case-control design was used to assess eye-head-trunk coordination for community-dwelling elders performing a stand-walk task. Eighteen elders with a high risk of falling were matched to 18 subjects with low risk on the basis of age, living status (living alone or with someone) and category of residence (independent living or assisted living facility). Standard electro-oculography was used in conjunction with an electromagnetic tracking device to measure eye and head-trunk motion, respectively. For the low-risk group, the mean slope of gaze-head and gaze-trunk relationships was significantly greater than zero (0.91 and 0.64, respectively), whereas high-risk elders did not demonstrate slope magnitudes significantly different from zero (0.52 and 0.16, respectively) due to large inter-subject variations. While the majority of subjects showed some counter-rotation of the eyes with head pitch, a greater percentage of subjects in the high-risk group did not suppress this response and consequently gaze and gaze velocity overcompensated for head pitch. These findings suggest that the vertical vestibulo-ocular reflex is not adequately suppressed during the stand-walk task in elders who are at a high risk of falling. Possible mechanisms contributing to these findings are discussed. [ABSTRACT FROM AUTHOR]