Click-evoked vestibulo-ocular reflex

Neurology ◽  
2006 ◽  
Vol 66 (7) ◽  
pp. 1079-1087 ◽  
Author(s):  
S. T. Aw ◽  
M. J. Todd ◽  
G. E. Aw ◽  
J. S. Magnussen ◽  
I. S. Curthoys ◽  
...  
Keyword(s):  
Semicircular Canal ◽  
Rotation Axis ◽  
Head Orientation ◽  
Superior Canal Dehiscence ◽  
Ocular Reflex ◽  
Eye Rotation ◽  
Vestibulo Ocular Reflex ◽  
Low Threshold ◽  
Canal Dehiscence ◽  
Click Polarity

Background: An enlarged, low-threshold click-evoked vestibulo-ocular reflex (VOR) can be averaged from the vertical electro-oculogram in a superior canal dehiscence (SCD), a temporal bone defect between the superior semicircular canal and middle cranial fossa.Objective: To determine the origin and quantitative stimulus–response properties of the click-evoked VOR.Methods: Three-dimensional, binocular eye movements evoked by air-conducted 100-microsecond clicks (110 dB normal hearing level, 145 dB sound pressure level, 2 Hz) were measured with dual-search coils in 11 healthy subjects and 19 patients with SCD confirmed by CT imaging. Thresholds were established by decrementing loudness from 110 dB to 70 dB in 10-dB steps. Eye rotation axis of click-evoked VOR computed by vector analysis was referenced to known semicircular canal planes. Response characteristics were investigated with regard to enhancement using trains of three to seven clicks with 1-millisecond interclick intervals, visual fixation, head orientation, click polarity, and stimulation frequency (2 to 15 Hz).Results: In subjects and SCD patients, click-evoked VOR comprised upward, contraversive-torsional eye rotations with onset latency of approximately 9 milliseconds. Its eye rotation axis aligned with the superior canal axis, suggesting activation of superior canal receptors. In subjects, the amplitude was less than 0.01°, and the magnitude was less than 3°/second; in SCD, the amplitude was up to 60 times larger at 0.66°, and its magnitude was between 5 and 92°/second, with a threshold 10 to 40 dB below normal (110 dB). The click-evoked VOR magnitude was enhanced approximately 2.5 times with trains of five clicks but was unaffected by head orientation, visual fixation, click polarity, and stimulation frequency up to 10 Hz; it was also present on the surface electro-oculogram.Conclusion: In superior canal dehiscence, clicks evoked a high-magnitude, low-threshold, 9-millisecond-latency vestibulo-ocular reflex that aligns with the superior canal, suggesting superior canal receptor hypersensitivity to sound.

The click-evoked vestibulo-ocular reflex in superior semicircular canal dehiscence

Neurology ◽  
2003 ◽  
Vol 60 (7) ◽  
pp. 1172-1175 ◽  
Author(s):  
G.M. Halmagyi ◽  
L. A. McGarvie ◽  
S. T. Aw ◽  
R. A. Yavor ◽  
M. J. Todd
Keyword(s):  
Semicircular Canal ◽  
Superior Semicircular Canal Dehiscence ◽  
Superior Semicircular Canal ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Canal Dehiscence

CLICK-EVOKED VESTIBULO-OCULAR REFLEX DISTINGUISHES POSTERIOR FROM SUPERIOR CANAL DEHISCENCE

Neurology ◽  
2010 ◽  
Vol 75 (10) ◽  
pp. 933-935 ◽  
Author(s):  
S. T. Aw ◽  
M. S. Welgampola ◽  
A. P. Bradshaw ◽  
M. J. Todd ◽  
J. S. Magnussen ◽  
...  
Keyword(s):  
Superior Canal Dehiscence ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Canal Dehiscence

scholarly journals Three-Dimensional Vibration-Induced Vestibulo-ocular Reflex Identifies Vertical Semicircular Canal Dehiscence

2011 ◽  
Vol 12 (5) ◽  
pp. 549-558 ◽  
Author(s):  
Swee Tin Aw ◽  
Grace Elizabeth Aw ◽  
Michael John Todd ◽  
Andrew Philip Bradshaw ◽  
Gabor Michael Halmagyi
Keyword(s):  
Semicircular Canal ◽  
Three Dimensional ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Vertical Semicircular Canal ◽  
Canal Dehiscence

Gauging the effectiveness of canal occlusion surgery: how I do it

2019 ◽  
Vol 133 (11) ◽  
pp. 1012-1016 ◽  
Author(s):  
F Hassannia ◽  
P Douglas-Jones ◽  
J A Rutka
Keyword(s):  
Semicircular Canal ◽  
Benign Paroxysmal Positional Vertigo ◽  
Superior Semicircular Canal Dehiscence ◽  
Head Impulse ◽  
Superior Semicircular Canal ◽  
Ocular Reflex ◽  
Positional Vertigo ◽  
Vestibulo Ocular Reflex ◽  
Canal Dehiscence ◽  
Paroxysmal Positional Vertigo

AbstractBackgroundTransmastoid occlusion of the posterior or superior semicircular canal is an effective and safe management option in patients with refractory benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence. A method of quantifying successful canal occlusion surgery is described.MethodsThis paper presents representative patients with intractable benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence, who underwent transmastoid occlusion of the posterior or superior semicircular canal respectively. Vestibular function was assessed pre- and post-operatively. The video head impulse test was included as a measure of semicircular canal and vestibulo-ocular reflex functions.ResultsPost-operative video head impulse testing showed reduced vestibulo-ocular reflex gain in occluded canals. Gain remained normal in the non-operated canals. Post-operative audiometry demonstrated no change in hearing in the benign paroxysmal positional vertigo patient and slight hearing improvement in the superior semicircular canal dehiscence syndrome patient.ConclusionTransmastoid occlusion of the posterior or superior semicircular canal is effective and safe for treating troublesome benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence. Post-operative video head impulse testing demonstrating a reduction in vestibulo-ocular reflex gain can reliably confirm successful occlusion of the canal and is a useful adjunct in post-operative evaluation.

Three Dimensional Eye Movements of Squirrel Monkeys Following Postrotatory Tilt

1993 ◽  
Vol 3 (2) ◽  
pp. 123-139 ◽  
Author(s):  
Daniel M. Merfeld ◽  
Laurence R. Young ◽  
Gary D. Paige ◽  
David L. Tomko
Keyword(s):  
Eye Movements ◽  
Time Course ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Head Orientation ◽  
Ocular Reflex ◽  
Eye Rotation ◽  
Acceleration And Deceleration ◽  
Vestibulo Ocular Reflex ◽  
Vertical Nystagmus

Three-dimensional squirrel monkey eye movements were recorded during and immediately following rotation around an earth-vertical yaw axis (160∘/s steady state, 100∘/s2 acceleration and deceleration). To study interactions between the horizontal angular vestibulo-ocular reflex (VOR) and head orientation, postrotatory VOR alignment was changed relative to gravity by tilting the head out of the horizontal plane (pitch or roll tilt between 15∘ and 90∘) immediately after cessation of motion. Results showed that in addition to post rotatory horizontal nystagmus, vertical nystagmus followed tilts to the left or right (roll), and torsional nystagmus followed forward or backward (pitch) tilts. When the time course and spatial orientation of eye velocity were considered in three dimensions, the axis of eye rotation always shifted toward alignment with gravity, and the postrotatory horizontal VOR decay was accelerated by the tilts. These phenomena may reflect a neural process that resolves the sensory conflict induced by this postrotatory tilt paradigm.

Kinematic Principles of Primate Rotational Vestibulo-Ocular Reflex I. Spatial Organization of Fast Phase Velocity Axes

1997 ◽  
Vol 78 (4) ◽  
pp. 2193-2202 ◽  
Author(s):  
Bernhard J. M. Hess ◽  
Dora E. Angelaki
Keyword(s):  
Phase Velocity ◽  
Velocity Component ◽  
Spatial Organization ◽  
Rotation Axis ◽  
Head Rotation ◽  
Underlying Mechanism ◽  
Head Orientation ◽  
Fast Phase ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

Hess, Bernhard J. M. and Dora E. Angelaki. Kinematic principles of primate rotational vestibulo-ocular reflex. I. Spatial organization of fast phase velocity axes. J. Neurophysiol. 78: 2193–2202, 1997. The spatial organization of fast phase velocity vectors of the vestibulo-ocular reflex (VOR) was studied in rhesus monkeys during yaw rotations about an earth-horizontal axis that changed continuously the orientation of the head relative to gravity (“barbecue spit” rotation). In addition to a velocity component parallel to the rotation axis, fast phases also exhibited a velocity component that invariably was oriented along the momentary direction of gravity. As the head rotated through supine and prone positions, torsional components of fast phase velocity axes became prominent. Similarly, as the head rotated through left and right ear-down positions, fast phase velocity axes exhibited prominent vertical components. The larger the speed of head rotation the greater the magnitude of this fast phase component, which was collinear with gravity. The main sequence properties of VOR fast phases were independent of head position. However, peak amplitude as well as peak velocity of fast phases were both modulated as a function of head orientation, exhibiting a minimum in prone position. The results suggest that the fast phases of vestibulo-ocular reflexes not only redirect gaze and reposition the eye in the direction of head motion but also reorient the eye with respect to earth-vertical when the head moves relative to gravity. As further elaborated in the companion paper, the underlying mechanism could be described as a dynamic, gravity-dependent modulation of the coordinates of ocular rotations relative to the head.

Spatial orientation of the angular vestibulo-ocular reflex

1999 ◽  
Vol 9 (3) ◽  
pp. 163-172
Author(s):  
Bernard Cohen ◽  
Susan Wearne ◽  
Mingjia Dai ◽  
Theodore Raphan
Keyword(s):  
Spatial Orientation ◽  
Optokinetic Nystagmus ◽  
Vestibular Nuclei ◽  
Velocity Storage ◽  
Gravitational Acceleration ◽  
Ocular Reflex ◽  
Eye Rotation ◽  
Slow Velocity ◽  
Vestibulo Ocular Reflex ◽  
Vector Sum

During vestibular nystagmus, optokinetic nystagmus (OKN), and optokinetic afternystagmus (OKAN), the axis of eye rotation tends to align with the vector sum of linear accelerations acting on the head. This includes gravitational acceleration and the linear accelerations generated by translation and centrifugation. We define the summed vector of gravitational and linear accelerations as gravito-inertial acceleration (GIA) and designate the phenomenon of alignment as spatial orientation of the angular vestibuloocular reflex (aVOR). On the basis of studies in the monkey, we postulated that the spatial orientation of the aVOR is dependent on the slow (velocity storage) component of the aVOR, not on the short latency, compensatory aVOR component, which is in head-fixed coordinates. Experiments in which velocity storage was abolished by midline medullary section support this postulate. The velocity storage component of the aVOR is likely to be generated in the vestibular nuclei, and its spatial orientation was shown to be controlled through the nodulus and uvula of the vestibulo-cerebellum. Separate regions of the nodulus/uvula appear to affect the horizontal and vertical/torsional components of the response differently. Velocity storage is weaker in humans than in monkeys, but responds in a similar fashion in both species. We postulate that spatial orientation of the aVOR plays an important role in aligning gaze with the GIA and in maintaining balance during angular locomotion.

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