Analysis of the vestibulo-ocular reflex time constant in patients with benign recurrent vertigo associated with head-shaking nystagmus

We assessed the influence of age on the otolith-ocular reflex and semicircular canal-otolith interaction. Healthy young (n=30) and healthy older (n=60) subjects were rotated about an earth vertical axis, and about a 30 degree off-vertical axis. Eye movements during and following rotation were recorded using electro-oculography. Results indicated that there were statistically significant changes in the otolith-ocular reflex and semicircular canal-otolith interaction as a function of age. The modulation component during off-vertical axis rotation (OVAR) was greater in the older group compard to the young adults, whereas the bias component was smaller with advanced age. The foreshortening of the vestibulo-ocular reflex time constant induced by post-rotatory head tilt following cessation of rotation was less prominent in the older group. There were no consistent changes in the semicircular canal-ocular reflex. Overall, response parameters showed more variability in the older subjects. We conclude that age related changes in the otolith-ocular reflex and semicircular canal-otolith interaction are a result primarily of a degradation of central vestibular processing of otolith signals rather than a decline of peripheral vestibular function.

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Short-term vestibular responses to repeated rotations

Journal of Vestibular Research ◽

10.3233/ves-2000-10103 ◽

2000 ◽

Vol 10 (1) ◽

pp. 17-23

Author(s):

Seung Cheol Ahn ◽

Chae Yong Lee ◽

Dong Wook Kim ◽

Moo Hoo Lee

Keyword(s):

Time Constant ◽

Phase Changes ◽

Short Term ◽

Mean Values ◽

Ocular Reflex ◽

Group I ◽

Vestibulo Ocular Reflex ◽

The Mean ◽

Group Ii ◽

Sinusoidal Rotations

To investigate the short-term vestibular habituation, we performed the 4 successive velocity step tests on 28 volunteers, the peak velocity of which was 100 deg/sec with acceleration and deceleration of 100 deg / sec 2 . As the repeated rotations might alter the vestibulo-ocular reflex (VOR), sinusoidal rotations at a frequency of 0.16 Hz were also given before and after the 4 successive velocity step tests to investigate the changes of gain and phase of VOR. The 28 volunteers were divided into two groups, group I and II, according to their responses to repeated rotations. In group I (25 subjects, mean age 23.7 year), the mean values of the slow cumulative eye position (SCEP), the time integral of eye velocity during nystagmus, was reduced after each trial of the 4-successive velocity step tests as follows; 403.4 ± 29 degree (1st trial), 346.2 ± 37 degree (2nd trial), 278.3 ± 33 degree (3rd trial) and 256.6 ± 36 degree (4th trial). The time constant of the nystagmus was also reduced as follows; 12.9 ± 0.78 second (1st trial), 12 ± 0.63 second (2nd trial), 9.7 ± 0.78 second (3rd trial) and 9.9 ± 0.54 second (4th trial). In group II (3 subjects, mean age 28.3 year), the mean values of SCEP gradually increased; 774.3 ± 135 degree (1st trial), 1127 ± 178 degree (2nd trial), 1096.3 ± 123.4 degree (3rd trial) and 1225.7 ± 199.7 degree (4th trial). The time constant of the nystagmus increased; 15.7 ± 2.7 second (1st trial), 22 ± 4.5 second (2nd trial), 22.3 ± 3.3 second (3rd trial) and 23.3 ± 5.7 second (4th trial). The gain of vestibulo-ocular reflex (VOR) induced by sinusoidal rotations at a frequency 0.16 Hz increased in both groups: 0.59 ± 0.03 to 0.78 ± 0.06 (group I) and 0.65 ± 0.07 to 1.15 ± 0.06 (group II). Phase changes were also observed. In group I, the phase was shifted from 0.6 ± 0.6 degree to − 0.40 ± 0.6 degree. In group II, the phase was shifted from 3.67 ± 1.86 degree to − 0.33 ± 0.33 degree. The repeated rotation did not induce a common nystagmic response in all subjects. Thus, person to person variations should be considered in short term vestibular habituation.

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Influence of Adaptation upon the Impulsive Time Constant of the Human Vestibulo-Ocular Reflex System

ORL ◽

10.1159/000275625 ◽

1983 ◽

Vol 45 (1) ◽

pp. 52-59

Author(s):

L.J.J.M. Boumans ◽

M. Rodenburg ◽

A.J.J. Maas

Keyword(s):

Time Constant ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Reflex System

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Clinical-pathologic correlation in a patient with selective loss of hair cells in the vestibular endorgans

Neurology ◽

10.1212/wnl.49.5.1377 ◽

1997 ◽

Vol 49 (5) ◽

pp. 1377-1382 ◽

Cited By ~ 10

Author(s):

R. W. Baloh ◽

I. Lopez ◽

K. Beykirch ◽

A. Ishiyama ◽

V. Honrubia

Keyword(s):

Time Constant ◽

Hair Cells ◽

Vestibular Function ◽

Cochlear Hair Cells ◽

Vestibular Hair Cells ◽

Selective Loss ◽

Ocular Reflex ◽

Hearing Function ◽

Vestibulo Ocular Reflex ◽

Vestibular Endorgans

We found a selective loss of vestibular hair cells in a patient followed for more than 10 years with imbalance and oscillopsia due to idiopathic progressive loss of vestibular function. Hearing function and cochlear hair cells were normal. The vestibulo-ocular reflex (VOR) gain at high frequencies was relatively maintained despite marked shortening of the dominant VOR time constant (to less than 500 ms). Ultrastructural examination of remaining hair cells showed mitochondrial abnormalities. The ultrashort VOR time constant probably resulted from changes in firing patterns of the primary afferent nerves due to loss of hair cells and impaired energy metabolism in remaining hair cells.

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Comparison of Vestibular Subjective Sensation and Nystagmus Responses during Computerized Harmonic Acceleration Tests

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348948209100506 ◽

1982 ◽

Vol 91 (5) ◽

pp. 493-500 ◽

Cited By ~ 5

Author(s):

Vicente Honrubia ◽

Herman A. Jenkins ◽

Robert W. Baloh ◽

Horst R. Konrad ◽

Robert D. Yee ◽

...

Keyword(s):

Time Constant ◽

Vestibular Function ◽

Normal Subjects ◽

Phase Measurements ◽

Ocular Reflex ◽

Pendulum Model ◽

Vestibulo Ocular Reflex ◽

Subjective Sensation

A comparison was made between the phase of vestibulo-ocular reflex (VOR) responses to sinusoidal rotatory tests and the phase of the subjective sensation (SS) to rotation. A parallelism was found between the results of both sets of data such that they behaved in accordance with the prediction of the pendulum model of vestibular function. The time constant of the VOR (17.5 seconds) was longer, however, than that of the SS (13 seconds). Measurements in patients with unilateral labyrinthine pathology also showed comparable changes in both responses. One group of patients with complete unilateral labyrinthine paralysis showed an advance of the phase of the VOR and of the SS. However, phase measurements in the group of patients with only partial unilateral labyrinthine paralysis were not significantly different statistically from those of normal subjects.

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Influence of Adaptation upon the Impulsive Time Constant of the Human Vestibulo-Ocular Reflex System

ORL ◽

10.1159/000275624 ◽

1983 ◽

Vol 45 (1) ◽

pp. 39-51 ◽

Cited By ~ 1

Author(s):

L.J.J.M. Boumans ◽

M. Rodenburg ◽

A.J.J. Maas

Keyword(s):

Time Constant ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Reflex System

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Unusual Vestibulo-Ocular Reflex Responses in Patients With Peripheral Vestibular Disorders Detected by the Caloric Step Stimulus Test

Frontiers in Neurology ◽

10.3389/fneur.2020.597562 ◽

2020 ◽

Vol 11 ◽

Author(s):

Motomu Honjo ◽

Keiji Honda ◽

Takeshi Tsutsumi

Keyword(s):

Time Constant ◽

Slow Phase ◽

Vestibular Disorders ◽

Rapid Rise ◽

Meniere Disease ◽

Time Constants ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Menière Disease ◽

Normal Controls

The caloric step stimulus test consists of the changes in head position from the sitting to supine positions and continuous caloric irrigation. This test can provide a single labyrinth with a stimulus similar to constant head acceleration in rotational testing and, therefore, can evaluate vestibulo-ocular reflex (VOR) dynamics more precisely than can conventional methods. To assess the clinical utility of the test in the assessment of the VOR dynamics of diseases, we performed the test in patients with peripheral vestibular disorders, including sudden idiopathic hearing loss, vestibular neuritis, Meniere disease, vestibular Meniere disease, or chronic unilateral idiopathic vestibulopathy and normal controls. Slow-phase eye velocity (SPV) was measured with videonystagmography. We fitted the time course of SPV across 2 min to a mathematical model containing two exponential components and time constants: the caloric step VOR time constant (T1) and caloric step VOR adaptation time constant (T2). All responses of normal controls (n = 15 ears) were fit to the model. Several responses of the 101 ears of the patients differed from the time courses predicted by the model. We divided the data of 116 ears into four patterns based on SPV, T1, and T2. The thresholds for the classification were determined according to the lower limits of the capability of curve fitting for SPV and the upper limits of normal controls for T1 and T2. Seventy-eight ears followed pattern A (normal T1 and T2): the SPV trajectory formed a rapid rise with subsequent decay. Nineteen followed pattern B (normal T1 and prolonged T2): the SPV trajectory formed a rapid rise without decay. Six followed pattern C (prolonged T1 and T2): the SPV trajectory formed a slow rise. Thirteen ears followed pattern D: a low VOR response. There were no significant differences in time constants between the affected and healthy ears in patients with each disease. However, prolonged T1 and T2 were significantly more frequent in the affected ears than the healthy ears. In conclusion, the caloric step stimulus test can be potentially useful in detecting unusual VOR responses and thus reflect some pathological changes in the vestibular system.

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Reduction of Gain and Time Constant of Vestibulo-Ocular Reflex in Man Induced by Diazepam and Thiopental

Journal of Vestibular Research ◽

10.3233/ves-1990-1110 ◽

1990 ◽

Vol 1 (1) ◽

pp. 97-104 ◽

Cited By ~ 1

Author(s):

Serge Padoan ◽

Kari Korttila ◽

Mans Magnusson ◽

Ilmari Pyykkö ◽

Lucyna Schalén

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Time Constant ◽

Intravenous Administration ◽

Blood Concentration ◽

Specific Effect ◽

Ocular Reflex ◽

Different Types ◽

Vestibulo Ocular Reflex ◽

Time Courses

The effect of intravenous administration of two sedatives, diazepam (0.3 mg/kg) and thiopental (6.0 mg/kg), on the vestibulo-ocular reflex (VOR) in man was investigated on 9 volunteers. The VOR was evoked with a velocity step rotation test and gain and time constant of perrotatory and postrotatory nystagmus were measured. Both drugs reduced VOR gain. Diazepam-induced reduction lasted 8 h and thiopental-induced reduction 1 h. A reduction of the VOR time constant was found lasting about 1 h for both drugs, but with a tendency for the thiopental effect to last longer. These findings, not previously described in man, differ from what has been found in macaques and rabbits injected with diazepam. The reduction of gain and time constant were not correlated with the blood concentration of either drug. The present results suggest that in man the VOR gain and time constant are both reduced by different types of sedatives although with different time courses. On the basis of previously shown effect of alertness on the VOR, it is hypothesized that diazepam and thiopental, besides having a specific effect on central nervous system structures important to the VOR, also induce reduction of the VOR through a general sedation of the CNS.

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Fitting Adaptation Models to Velocity Step Responses: Simulation of Normal and Abnormal Responses

Journal of Vestibular Research ◽

10.3233/ves-1992-2104 ◽

1992 ◽

Vol 2 (1) ◽

pp. 41-57

Author(s):

P.L.M. Huygen ◽

M.G.M. Nicolasen

Keyword(s):

Time Constant ◽

General Model ◽

Variable Gain ◽

Ocular Reflex ◽

Suitable Parameter ◽

Long Time ◽

Vestibulo Ocular Reflex ◽

Particular Solution ◽

Parameter Values ◽

Adaptation Model

A method is described to obtain suitable parameter values for an adaptation model that can be used to simulate velocity step (VS) responses. The input parameters are the dominant time constant fitted to the first part of the VS response and the time of reversal in nystagmus direction. This method allows a particular solution for the model previously defined by others with a vestibulo-ocular reflex (VOR) time constant, a time constant of adaptation, and a fixed (unitary) gain of the adaptation element. However, because it might be arbitrary to assume a unitary gain, we also studied a more general model with a variable gain element. It appeared that patients showing short responses had a short VOR time constant and less adaptation than normal. Patients exhibiting prolonged responses appeared to have an excessively long VOR time constant and more adaptation than normal, presumably to compensate for the long time constant.

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