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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 prerotatory and postrotatory nystagmus were measured. Both drugs reduced VOR gain. Diazepam-induced reduction lasted 8 h and thiop
Fourteen patients with vestibular neuritis were examined at onset of symptoms and after one year. Postrotatory time constant and gain in the vestibulo-ocular reflex (VOR) were measured after rotation with a velocity step of 150 deg/s. There was no significant difference in gain towards the healthy side at onset of the disease compared to recordings after one year. The time constant towards the hea
Human postural control works as a dynamic feedback control system. The dynamic performance of postural control for anterior-posterior movements during upright posture are defined by three parameters. These parameters reflect the stiffness, the damping and the swiftness of a response to an induced perturbation. In the present study 23 normal subjects were investigated. Both with open and closed eye
The effects of i.v. injection of diazepam 0.3 mg/kg and thiopental 6.0 mg/kg on vestibulo-ocular reflex (VOR) were studied in 9 healthy volunteers. One hour after injection of both diazepam and thiopental VOR gain was reduced and time constant shortened. Four hours after intravenous injection of diazepam the VOR gain was still significantly reduced and had not yet returned to control 8 h after inj
Seventy-nine consecutive patients, 70 patients with acoustic neurinomas (ACN) and 9 patients with cerebello-pontine angle tumours of other etiology (o-CPA) were analysed with respect to tumour size and the result of the caloric and oculomotor tests. The size of the tumour was judged by the largest diameter calculated from the computerized tomography. A highly significant linear relationship betwee
Postural control is maintained by sensory feedback from visual, vestibular and somatosensory receptors. Recently several methods for evaluating postural control have been devised, utilizing an imposed perturbation. Most of these methods use stimuli which simultaneously affect more than one of the sensory feedback loops. In the present paper a posturographic technique is presented with specific loa
During recent decades a vast amount of literature concerning horizontal optokinetic nystagmus has emerged, regarding which--and especially as regards our own work--this report is intended to consider the clinical value of optokinetic nystagmus.
The eye tracking test is today a well established part of clinical otoneurological examination. In the present paper some applications of the test in evaluating of the level of lesion within the vestibular system are reviewed.
A review of the treatment of vestibular disorders with drugs is presented. In animal experiments, administration of certain drugs, e.g. alcohol, barbiturates and chlorpromazine, retards the vestibular compensation, while others, e.g. caffeine, amphetamine and ACTH, accelerate the compensation. In compensated animals, some drugs produce overcompensation and some decompensation. A double-blind, rand
Optokinetic nystagmus (OKN) was studied in ten patients with vestibular neuritis, and in seventeen patients with unilateral and thirteen patients with bilateral infratentorial lesions and compared with OKN in fifty healthy subjects. Mean and maximum slow phase velocity of OKN was calculated as well as the asymmetry of responses. The efficiency of the different variables in OKN, in discriminating b
Many subjects have a negative spike in the beginning of a saccade in electro-oculographic signals. The amplitude of the spike depends on the location of the electrodes. The spike distorts the saccades and causes errors in the parameters. The saccade spike can assist in the identification of small saccades. A syntactic technique based on formal languages and parsing is presented which looks for spi
Electrical brain activity and eye movements were recorded in 10 intact and 6 unilaterally labyrinthectomized rabbits, each with implanted electrodes. The frequency of optokinetic nystagmus (OKN) and a 10-second aggregate of theta waves in the dorsal hippocampus were determined after exposure of the animals to sound, vibration and optokinetic stimulation. Each stimulus used caused significant incre
The effect of alertness on the time constant of the vestibulo-ocular reflex (VOR) and the time constant of the slow rise of the optokinetic nystagmus (OKN) was studied in nine pigmented rabbits. When the rabbits were alerted by vibration, the time constant of the VOR was prolonged, and that of the slow rise in OKN was shortened, whereas the gain of VOR and OKN remained largely unaffected. These fi
Optokinetic nystagmus (OKN) at a constant stimulus velocity of 90 degrees/s was studied in 50 healthy subjects and three different groups of patients: 10 with vestibular neuritis (VN), 17 with unilateral infratentorial lesion (UI) and 13 patients with bilateral infratentorial lesion (BI). Among healthy subjects, OKN decreased with age in those over 42 and 44 years for maximum and mean velocity, re
The relationship of mean velocity of optokinetic nystagmus (OKN) to pursuit eye movements (PEM), to vestibular nystagmus and to voluntary saccades was analysed in 10 patients with peripheral vestibular lesions and in 30 patients with central vestibular lesions. PEM and vestibular nystagmus were significantly correlated to OKN, suggesting that a common neural pathway is used in the generation of th
The effect of alertness and visual attention on optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) was studied in 20 volunteers. Electroencephalographic (EEG) activity was recorded over the occipital lobe. Exposure to sound and vibration caused a significant increase in the mean slow-phase velocity of OKN, whereas its maximum slow-phase velocity remained unaffected. Vibration tende
Saccadic eye movements provide important information about the neuron system at several levels. In recent years computer analysis of saccades has been adapted for use in clinical work. The most common detection methods do not always function without the user's control and aid. In the present paper a digital filter is described for the detection of saccades. This non-recursive filter unscrambles sa
