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

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.

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.

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.

Enhanced vestibulo-ocular reflex suppression in dancers during passive high-velocity head impulses

2018 ◽  
Vol 237 (2) ◽  
pp. 411-416
Author(s):  
Maxime Maheu ◽  
L. Behtani ◽  
M. Nooristani ◽  
A. Delcenserie ◽  
F. Champoux
Keyword(s):  
High Velocity ◽  
Velocity Head ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Head Impulses

Effect of vestibular rehabilitation on passive dynamic visual acuity

2008 ◽  
Vol 18 (2-3) ◽  
pp. 147-157
Author(s):  
Matthew Scherer ◽  
Americo A. Migliaccio ◽  
Michael C. Schubert
Keyword(s):  
Visual Acuity ◽  
Exercise Program ◽  
Home Exercise ◽  
Dynamic Visual Acuity ◽  
Gaze Stabilization ◽  
Ocular Reflex ◽  
Gaze Stability ◽  
Before And After ◽  
Vestibulo Ocular Reflex ◽  
Head Impulses

While active dynamic visual acuity (DVA) has been shown to improve with gaze stabilization exercises, we sought to determine whether DVA during {passive} head impulses (pDVA) would also improve following a rehabilitation course of vestibular physical therapy (VPT) in patients with unilateral and bilateral vestibular hypofunction. VPT consisted of gaze and gait stabilization exercises done as a home exercise program. Scleral search coil was used to characterize the angular vestibulo-ocular reflex (aVOR) during pDVA before and after VPT. Mean duration of VPT was 66 ± 24 days, over a total of 5 ± 1.4 outpatient visits. Two of three subjects showed improvements in pDVA with a mean reduction of 43% (LogMAR 0.58 to 0.398 and 0.92 to 0.40). Our data suggest improvements in pDVA may be due in part to improvements in aVOR velocity and acceleration gains or reduced latency of the aVOR. Each subject demonstrated a reduction in the ratio of compensatory saccades to head impulses after VPT. Preliminary data suggest that active gaze stability exercises may contribute to improvements in pDVA in some individuals.

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