The effect of an asymmetric vestibular input on the symmetry of horizontal optokinetic after-nystagmus (OKAN) was studied in twenty healthy subjects. Optokinetic nystagmus (OKN) was elicited by a whole-field optokinetic drug, rotating at 90 degrees/s, and eye-movements were recorded by a DC electro-oculographic technique (EOG). The ratio of OKAN following right and left-beating OKN respectively wa

The importance to postural control of the mechanoreceptors of the soles was investigated in thirteen healthy subjects. Body-sway velocity was evaluated before and after exposing the subject's feet to hypothermia, and when calf muscles were exposed to vibration at frequencies between 20 and 100 Hz. Subjects were tested both with eyes open and closed. Body-sway velocity was found to increase signifi

Anterior-posterior body sway was evoked with monopolar bi-aural galvanic stimulus of the vestibular nerves in normal subjects and recorded with a force platform, two experiments being conducted. In an experiment of paired design, 9 normal subjects showed an increase in anterior-posterior sway as compared with lateral sway when exposed to the stimulus. In a second experiment another group of 10 nor

Directional asymmetry of primary and secondary optokinetic afternystagmus (OKAN I and OKAN II, respectively) was studied in 20 patients with small acoustic neurinomas (< or = 20 mm), and results were compared to those for 24 normal controls. The optokinetic afterresponse was induced by 60 s of horizontal whole-field optokinetic stimulation in both directions. Among patients, the optokinetic afterr

The symmetry of primary and secondary optokinetic afternystagmus (OKAN I and OKAN II, respectively) was studied in 14 patients with vestibular neuritis, as well as in 50 normals. The patients were examined at onset of symptoms and at follow-up 3 and 12 months later. At onset, OKAN was found mainly to reflect the spontaneous nystagmus. Although the spontaneous nystagmus disappeared in all patients

The effect of inhaling nitrous oxide on pursuit eye movements (PEM) and voluntary saccades was studied in nine healthy subjects. Eye movements were recorded before, during, and 10 min after exposure for 15 min to normoxic mixtures of 14%, 21%, and 28% nitrous oxide. At all concentrations, there was a significant decrease in gain of PEM at a target velocity of 60 degrees/s, the decrease being of co

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