The Human Horizontal Vestibulo-Ocular Reflex in Response to Active and Passive Head Impulses after Unilateral Vestibular Deafferentation

2003 ◽  
Vol 1004 (1) ◽  
pp. 325-336 ◽  
Author(s):  
G. M. HALMAGYI ◽  
R. A. BLACK ◽  
M. J. THURTELL ◽  
I. S. CURTHOYS
Keyword(s):  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Unilateral Vestibular Deafferentation ◽  
Head Impulses

Head Impulses After Unilateral Vestibular Deafferentation Validate Ewald’s Second Law1

1991 ◽  
Vol 1 (2) ◽  
pp. 187-197
Author(s):  
G.M. Halmagyi ◽  
I.S. Curthoys ◽  
P.D. Cremer ◽  
C.J. Henderson ◽  
M. Staples
Keyword(s):  
Head Rotation ◽  
Normal Subjects ◽  
Head Movements ◽  
Afferent Neurons ◽  
Horizontal Semicircular Canal ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Unilateral Vestibular Deafferentation ◽  
Head Impulses ◽  
Stimulation Of

To determine the relative contributions of ampullofugal (AF) and ampullopetal (AP) stimulation of the horizontal semicircular canal (HSCC) to the horizontal vestibulo-ocular reflex (HVOR), 12 patients were studied 1 year after total unilateral vestibular deafferentation (UVD). Compensatory eye movement responses to impulses of horizontal head rotation were studied using magnetic search coils. The head impulses were rapid (up to 3000 deg/sec/sec) passive, unpredictable, step displacements of horizontal angular head position with respect to the trunk. Tbe results from these 12 patients were compared with results from 30 normal subjects. An HVOR deficit was found to each side. The HVOR in response to head impulses toward the deafferented side, a response generated exclusively by ampullofugal stimulation of the single functioning HSCC, was severely deficient with an average gain of 0.25; the HVOR in response to head impulses toward the intact side, a response generated exclusively by ampullopetal stimulation of the single functioning HSCC, was mildly but significantly deficient compared with normal subjects. These results show that rapid, unpredictable head movements, unlike slow, predictable head movements, do demonstrate the AP-AF HVOR asymmetry, which could be expected from consideration of the behavior of single vestibular afferent neurons, an asymmetry that is expressed by Ewald’s 2nd Law.

The Vestibulo-Ocular Reflex Response to Head Impulses Rarely Decreases after Cochlear Implantation

2005 ◽  
Vol 26 (4) ◽  
pp. 655-660 ◽  
Author(s):  
Americo A Migliaccio ◽  
Charles C. Della Santina ◽  
John P Carey ◽  
John K Niparko ◽  
Lloyd B Minor
Keyword(s):  
Cochlear Implantation ◽  
Reflex Response ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Head Impulses

scholarly journals The Effect of Different Head Movement Paradigms on Vestibulo-Ocular Reflex Gain and Saccadic Eye Responses in the Suppression Head Impulse Test in Healthy Adult Volunteers

2021 ◽  
Vol 12 ◽  
Author(s):  
Dmitrii Starkov ◽  
Bernd Vermorken ◽  
T. S. Van Dooren ◽  
Lisa Van Stiphout ◽  
Miranda Janssen ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Healthy Adult ◽  
Head Movements ◽  
Head Impulse Test ◽  
Head Impulse ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Reflex Gain ◽  
Head Impulses ◽  
Adult Volunteers

Objective: This study aimed to identify differences in vestibulo-ocular reflex gain (VOR gain) and saccadic response in the suppression head impulse paradigm (SHIMP) between predictable and less predictable head movements, in a group of healthy subjects. It was hypothesized that higher prediction could lead to a lower VOR gain, a shorter saccadic latency, and higher grouping of saccades.Methods: Sixty-two healthy subjects were tested using the video head impulse test and SHIMPs in four conditions: active and passive head movements for both inward and outward directions. VOR gain, latency of the first saccade, and the level of saccade grouping (PR-score) were compared among conditions. Inward and active head movements were considered to be more predictable than outward and passive head movements.Results: After validation, results of 57 tested subjects were analyzed. Mean VOR gain was significantly lower for inward passive compared with outward passive head impulses (p < 0.001), and it was higher for active compared with passive head impulses (both inward and outward) (p ≤ 0.024). Mean latency of the first saccade was significantly shorter for inward active compared with inward passive (p ≤ 0.001) and for inward passive compared with outward passive head impulses (p = 0.012). Mean PR-score was only significantly higher in active outward than in active inward head impulses (p = 0.004).Conclusion: For SHIMP, a higher predictability in head movements lowered gain only in passive impulses and shortened latencies of compensatory saccades overall. For active impulses, gain calculation was affected by short-latency compensatory saccades, hindering reliable comparison with gains of passive impulses. Predictability did not substantially influence grouping of compensatory saccades.

Vestibulo-ocular reflex dynamics with head-impulses discriminates spinocerebellar ataxias types 1, 2 and 3 and Friedreich ataxia

2016 ◽  
Vol 26 (3) ◽  
pp. 327-334 ◽  
Author(s):  
L. Luis ◽  
J. Costa ◽  
E. Muñoz ◽  
M. de Carvalho ◽  
S. Carmona ◽  
...  
Keyword(s):  
Friedreich Ataxia ◽  
Spinocerebellar Ataxias ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Head Impulses

Effects of Unilateral Vestibular Deafferentation on the Linear Vestibulo-Ocular Reflex Evoked by Impulsive Eccentric Roll Rotation

2003 ◽  
Vol 89 (2) ◽  
pp. 969-978 ◽  
Author(s):  
S. T. Aw ◽  
M. J. Todd ◽  
L. A. McGarvie ◽  
A. A. Migliaccio ◽  
G. M. Halmagyi
Keyword(s):  
Rotation Axis ◽  
Normal Subjects ◽  
Stimulus Onset ◽  
Whole Body ◽  
Viewing Distance ◽  
Ocular Reflex ◽  
Significant Difference ◽  
Vestibulo Ocular Reflex ◽  
Unilateral Vestibular Deafferentation ◽  
Eye Velocity

The effects of unilateral vestibular deafferentation (UVD) on the linear vestibulo-ocular reflex (LVOR) were studied by measuring three-dimensional eye movements in seven UVD subjects evoked by impulsive eccentric roll rotation while viewing an earth-fixed target at 200, 300, or 600 mm and comparing their responses to 11 normal subjects. The stimulus, a whole-body roll of approximately 1°, with the eye positioned 815 mm eccentric to the rotation axis, produced an inter-aural linear acceleration of approximately 0.5 g and a roll acceleration of approximately 360°/s2. The responses generated by the LVOR comprise horizontal eye rotations. Horizontal eye velocity at 100 ms from stimulus onset in UVD subjects was significantly lower than in normal subjects for all viewing distances, with no significant difference between ipsilesional and contralesional responses. LVOR acceleration gain, defined as the slope of actual horizontal eye velocity divided by the slope of ideal horizontal eye velocity during a 30-ms period starting 70 ms from stimulus onset, was bilaterally significantly reduced in UVD subjects at all viewing distances. Acceleration gain from all viewing distances was 1.04 ± 0.28 in normal subjects, and in UVD subjects was 0.49 ± 0.23 for ipsilesional and 0.63 ± 0.27 for contralesional acceleration. LVOR enhancement in the first 100 ms by near viewing was still present in UVD subjects. LVOR latency in UVD subjects (approximately 39 ms) was not significantly different from normal subjects (approximately 36 ms). After UVD, LVOR is bilaterally and largely symmetrically reduced, but latency remains unchanged and modulation by viewing distance is still present.

Absence of a vergence-mediated vestibulo-ocular reflex gain increase does not preclude adaptation

2021 ◽  
pp. 1-9
Author(s):  
Béla Büki (Family name Büki) ◽  
László T. Tamás (Family name Tamás) ◽  
Christopher J. Todd ◽  
Michael C. Schubert ◽  
Americo A. Migliaccio
Keyword(s):  
Laser Target ◽  
Head Velocity ◽  
Gain Enhancement ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Vor Adaptation ◽  
Reflex Gain ◽  
Head Impulses ◽  
Eye Velocity ◽  
Vestibular Pathways

BACKGROUND: The gain (eye-velocity/head-velocity) of the angular vestibuloocular reflex (aVOR) during head impulses can be increased while viewing near-targets and when exposed to unilateral, incremental retinal image velocity error signals. It is not clear however, whether the tonic or phasic vestibular pathways mediate these gain increases. OBJECTIVE: Determine whether a shared pathway is responsible for gain enhancement between vergence and adaptation of aVOR gain in patients with unilateral vestibular hypofunction (UVH). MATERIAL AND METHODS: 20 patients with UVH were examined for change in aVOR gain during a vergence task and after 15-minutes of ipsilesional incremental VOR adaptation (uIVA) using StableEyes (a device that controls a laser target as a function of head velocity) during horizontal passive head impulses.A 5 % aVOR gain increase was defined as the threshold for significant change. RESULTS: 11/20 patients had >5% vergence-mediated gain increase during ipsi-lesional impulses. For uIVA, 10/20 patients had >5% ipsi-lesional gain increase. There was no correlation between the vergence-mediated gain increase and gain increase after uIVA training. CONCLUSION: Vergence-enhanced and uIVA training gain increases are mediated by separate mechanisms and/or vestibular pathways (tonic/phasic).The ability to increase the aVOR gain during vergence is not prognostic for successful adaptation training.

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