The Mid-lateral Region of the Utricle Generates the Human Transaural Linear Vestibulo-Ocular Reflex (original) (raw)
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Vibration-Induced Nystagmus After Acute Peripheral Vestibular Loss
Otology & Neurotology, 2011
Objective: To validate the role of vibration-induced nystagmus (VIN) detecting vestibular asymmetry by comparing several vestibulo-ocular reflex (VOR) parameters in the yaw plane. Study Design: Prospective validation study for diagnostic test. Setting: Tertiary referral center. Patients: Seventy-four patients with unilateral vestibular loss of acute onset without a history of fluctuating vestibular function and 24 healthy volunteers. Intervention: Spontaneous nystagmus, head-shaking nystagmus (HSN), and VIN using a 100 Hz handheld vibrator were recorded using a videonystagmography system. Canal paresis on the caloric test and the time constant (TC) on the step velocity test were examined as parameters of the laboratory test. Main Outcome Measures: Correlation analysis between horizontal VOR parameters was performed. Receiver operating characteristic (ROC) curves of these parameters were plotted, and the area under the ROC curve (AUC) was compared according to the lower limiting value of TC on step velocity test as well as the presence of unilateral vestibular loss. Results: VIN was observed in 64 (86%) of 74 patients, and it was directed toward the contralesional side in 98%. VIN showed a significant positive correlation with the canal paresis (r = 0.416, p G 0.001) and a negative correlation with the TC (r = j0.351, p G 0.005). ROC curves of several VOR parameters were compared according to the presence of unilateral vestibular loss. The AUC of VIN was 0.882, and the cutoff intensity of VIN was 2.5 degrees per second. The AUCs of the HSN and spontaneous nystagmus were 0.774 and 0.661, respectively. Conclusion: The lateralization value of VIN was comparable with caloric test and superior to HSN. VIN is a useful vestibular test detecting vestibular asymmetry in the evaluation of dizziness.
Vestibular Loss: Asymmetry and Compensation
2015
The aim of this study was to analyse torsional optokinetic nystagmus (tOKN) in 17 patients with Menière’s disease before and after (1 week, 1 month and 3 months) a curative unilateral vestibular neurotomy (UVN). The tOKN was investigated during optokinetic stimulations around the line of sight directed towards either the lesioned or the healthy side, at various constant angular velocities. Dynamic properties of tOKN and static ocular cyclotorsion were analysed using videonystagmography. Patients ’ performances were compared with those of 10 healthy subjects. The results indicate that, in the acute stage after UVN, patients exhibited drastic impairment of tOKN velocity that depended on the direction of stimulation: tOKN velocity increased for ipsilesional stimulations and decreased for contralesional stimulations. These changes were responsible for a dramatic tOKN asymmetry, with ipsilesional directional preponderance of torsional slow-phase eye velocity. The changes were associated...
Vestibular Perception following Acute Unilateral Vestibular Lesions
PLoS ONE, 2013
Little is known about the vestibulo-perceptual (VP) system, particularly after a unilateral vestibular lesion. We investigated vestibulo-ocular (VO) and VP function in 25 patients with vestibular neuritis (VN) acutely (2 days after onset) and after compensation (recovery phase, 10 weeks). Since the effect of VN on reflex and perceptual function may differ at threshold and supra-threshold acceleration levels, we used two stimulus intensities, acceleration steps of 0.5u/s 2 and velocity steps of 90u/s (acceleration 180u/s 2 ). We hypothesised that the vestibular lesion or the compensatory processes could dissociate VO and VP function, particularly if the acute vertiginous sensation interferes with the perceptual tasks. Both in acute and recovery phases, VO and VP thresholds increased, particularly during ipsilesional rotations. In signal detection theory this indicates that signals from the healthy and affected side are still fused, but result in asymmetric thresholds due to a lesioninduced bias. The normal pattern whereby VP thresholds are higher than VO thresholds was preserved, indicating that any 'perceptual noise' added by the vertigo does not disrupt the cognitive decision-making processes inherent to the perceptual task. Overall, the parallel findings in VO and VP thresholds imply little or no additional cortical processing and suggest that vestibular thresholds essentially reflect the sensitivity of the fused peripheral receptors. In contrast, a significant VO-VP dissociation for supra-threshold stimuli was found. Acutely, time constants and duration of the VO and VP responses were reduced -asymmetrically for VO, as expected, but surprisingly symmetrical for perception. At recovery, VP responses normalised but VO responses remained shortened and asymmetric. Thus, unlike threshold data, supra-threshold responses show considerable VO-VP dissociation indicative of additional, higher-order processing of vestibular signals. We provide evidence of perceptual processes (ultimately cortical) participating in vestibular compensation, suppressing asymmetry acutely in unilateral vestibular lesions.
Three-Dimensional Human VOR in Acute Vestibular Lesions
Annals of the New York Academy of Sciences, 1996
The vestibuloocular reflex (VOR) has usually been studied one-dimensionally both in normals and in patients with vestibular lesions, by examining its horizontal, vertical, or, more recently, torsional component in isolation. In reality, however, the input and output of the VOR are not scalars but three-component vectors (the angular velocity vectors of the head and eye), and so a more complete characterization of the VOR requires a description, not only of the relative sizes of the eye and head velocities, but also of their relative directions, that is, the axes about which the
Vestibular function in severe bilateral vestibulopathy
Journal of Neurology Neurosurgery and Psychiatry, 2001
Objectives-To assess residual vestibular function in patients with severe bilateral vestibulopathy comparing low frequency sinusoidal rotation with the novel technique of random, high acceleration rotation of the whole body. Methods-Eye movements were recorded by electro-oculography in darkness during passive, whole body sinusoidal yaw rotations at frequencies between 0.05 and 1.6 Hz in four patients who had absent caloric vestibular responses. These were compared with recordings using magnetic search coils during the first 100 ms after onset of whole body yaw rotation at peak accelerations of 2800°/s 2 . OV centre rotations added novel information about otolithic function. Results-Sinusoidal yaw rotations at 0.05 Hz, peak veocity 240°/s yielded minimal responses, with gain (eye velocity/head velocity)<0.02, but gain increased and phase decreased at frequencies between 0.2 and 1.6 Hz in a manner resembling the vestibulo-ocular reflex. By contrast, the patients had profoundly attenuated responses to both centred and eccentric high acceleration transients, representing virtually absent responses to this powerful vestibular stimulus. Conclusion-The analysis of the early ocular response to random, high acceleration rotation of the whole body disclosed a profound deficit of semicircular canal and otolith function in patients for whom higher frequency sinusoidal testing was only modestly abnormal. This suggests that the high frequency responses during sinusoidal rotation were of extravestibular origin. Contributions from the somatosensory or central predictor mechanisms, might account for the generation of these responses. Random, transient rotation is better suited than steady state rotation for quantifying vestibular function in vestibulopathic patients. (J Neurol Neurosurg Psychiatry 2001;71:53-57)
Experimental Brain Research, 2007
Dynamic changes of deficits in canal and otolith vestibulo-ocular reflexes (VORs) to high acceleration, eccentric yaw rotations were investigated in five subjects aged 25–65 years before and at frequent intervals 3–451 days following unilateral vestibular deafferentation (UVD) due to labyrinthectomy or vestibular neurectomy. Eye and head movements were recorded using magnetic search coils during transients of directionally random, whole-body rotation in darkness
Auris Nasus Larynx, 2002
Objecti6e: To examine our hypothesis that an unusual floating or tilting sensation claimed by patients with long-standing unilateral vestibular loss might be attributed to incomplete central compensation in the otolith system. Methods: Seven patients who were with or without symptoms for 6-101 months after intratympanic gentamicin therapy for unilateral endolymphatic hydrops were sinusoidally exposed to lateral linear acceleration, and their compensatory eye movements were compared with those of 18 normal controls, using electro-oculography (EOG). The subjects, secured firmly in the chair of a linear accelerator (sled), were oscillated at three different G-loadings of 0.1 (0.11 Hz), 0.2 (0.16 Hz) and 0.3 G (0.19 Hz), respectively. During displacement, they gazed at a real (visible) or imaginary target which was located on the wall (earth-fixed), or moved on the wall in sync with the sled (body-fixed). Results: Vertical EOG (V-EOG) with a frequency two-fold that of the stimulus frequency was characteristically evoked in all patients, but in none of the normal controls. One of the doubled V-EOG was larger in amplitude than the other, when the stimulus acceleration was directed from the affected ear to the intact ear in those patients whose symptoms still remained. Such a directional difference tended to be greater with the imaginary target than with the visible target. In the horizontal EOG, there was no marked difference between the patients and normal controls. Nobody reported tilt perception but only horizontal translation during the sled displacement, except one patient who was examined twice; a roll tilt was perceived in the first examination when she still had symptoms, but no tilt sensation in the second one when she no longer had symptoms. Conclusion: It was suggested that incomplete compensation in the otolith system could cause unusual sensations even after long-standing unilateral vestibular loss, and that V-EOG induced by a sled might be helpful in evaluating functional recovery.
Neuroscience, 1999
In decerebrate cats after acute hemilabyrinthectomy, the response sensitivity of extracellularly recorded vestibular nuclear neurons on the lesioned and labyrinth-intact sides were examined quantitatively during constant velocity off-vertical axis rotations with an aim to elucidate the functional contribution of otolithic inputs to the ipsilateral and contralateral vestibular nuclei. The bidirectional response sensitivity, d, was determined as the ratio of the gain during clockwise to that during counterclockwise rotations. A continuum of response sensitivity was identified: one-dimensional neurons showed symmetrically bidirectional response patterns, while two-dimensional neurons showed asymmetrically bidirectional patterns that in some cases approached unidirectional patterns with change in velocity. The proportion of two-dimensional neurons was significantly increased after acute hemilabyrinthectomy. Two-dimensional neurons that responded only to one direction of rotation in at least one of the velocities tested were described as unidirectional neurons. This unidirectional response pattern was observed in one-third of the entire neuronal population studied, but not in cats with both labyrinths intact, thus suggesting that such prominent broadly tuned responses are normally masked by converging otolithic inputs from the contralateral side. These neurons were found in higher proportion on the lesioned side than on the labyrinth-intact side. Among the 70% of unidirectional neurons that exhibited bidirectional response at some velocities and unidirectional response at others, prominent shifts in d values (i.e. between 0/∞ and finite values) with velocity can be computed for each neuron. The shifts in d values correlated with large shifts in the response dynamics and spatial orientation as the response pattern changed with velocity. The response orientations of the unidirectional neurons pointed in all directions on the horizontal plane. When all the two-dimensional neurons (i.e. both the unidirectionally and bidirectionally responsive ones) were pooled, imbalances in the distribution of the response orientations and in response gain were found between the ipsilateral-sidedown/head-down half-circle and the contralateral-side-down/head-up half-circle on the labyrinth-intact side, but not on the lesioned side. These results, derived from spatiotemporal processing of gravitational signals, reveal a novel dimension of imbalance between neuronal populations in the two vestibular nuclear complexes after acute lesion of one labyrinth. This feature would provide, on the one hand, deranged cues of spatial orientation and direction during slow head excursions and, on the other, a framework for the dynamic behavioral deficits associated with hemilabyrinthectomy.