| 1. |
- Schalén, L, et al.
(författare)
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Clinical aspects of eye tracking test
- 1988
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Ingår i: Acta Oto-Laryngologica, Supplement. - : Informa UK Limited. - 0365-5237 .- 0001-6489 .- 1651-2251. ; 105:Suppl 455, s. 28-32
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 2. |
- Enbom, Håkan, et al.
(författare)
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Presentation of a posturographic test with loading of the proprioceptive system
- 1988
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Ingår i: Acta Oto-Laryngologica, Supplement. - 0365-5237. ; 455, s. 58-61
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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 loading of the proprioceptive system, using a computer controlled vibratory stimulus and computerized analysis of the results.
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| 3. |
- Juhola, M, et al.
(författare)
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An identification technique for the spike artefact of saccadic eye movements
- 1987
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Ingår i: Biological Cybernetics. - 0340-1200. ; 57:6, s. 20-415
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Tidskriftsartikel (refereegranskat)abstract
- 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 spikes from the electro-oculographic signal. For calculation of the algorithm, saccades from the photoelectric signal have been concurrently recorded and compared with the electro-oculographic signal.
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| 4. |
- Juhola, M, et al.
(författare)
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Detection of saccadic eye movements using a non-recursive adaptive digital filter
- 1985
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Ingår i: Computer Methods and Programs in Biomedicine. - 0169-2607. ; 21:2, s. 8-81
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Tidskriftsartikel (refereegranskat)abstract
- 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 saccade data which has been collected during the execution of an algorithm. The method is suitable for use with microcomputers. The filter is adaptive. Two concise experiments using the method are described.
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| 5. |
- Magnusson, M, et al.
(författare)
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Clinical considerations concerning horizontal optokinetic nystagmus
- 1988
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Ingår i: Acta Oto-Laryngologica, Supplement. - 0365-5237. ; 455, s. 7-53
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 6. |
- Magnusson, M, et al.
(författare)
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Reduction of the time constant in the VOR as a protective mechanism in acute vestibular lesions
- 1989
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Ingår i: Acta Oto-Laryngologica, Supplement. - 0365-5237. ; 468, s. 32-329
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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 healthy side was significantly shorter at onset compared to measurements after one year. The results reflect the loss of unilateral vestibular function on the velocity storage mechanism, both in the acute situation and after compensation. The findings indicate that reduction of the time constant in the VOR is not only due to unilaterally vestibular impairment but it is also an effect of the generally reduced activity in the vestibular system after a lesion and may act as protective mechanism in acute vertigo.
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| 7. |
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| 8. |
- Pyykkö, I., et al.
(författare)
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A reduction of vestibulo-visual integration during transdermally administered scopolamine and dimenhydrinate. A presentation of gain control theory in motion sickness
- 1984
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Ingår i: Acta Oto-Laryngologica, Supplement. - : Informa UK Limited. - 0365-5237 .- 0001-6489 .- 1651-2251. ; 406, s. 73-167
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The effect of transdermally administered scopolamine (TTS scopolamine) (release rate 5 micrograms/h) and dimenhydrinate (100 mg) was examined on optovestibular nystagmus in 16 volunteers in a randomized double-blind trial. A statistically significant decrease in the optokinetic part of nystagmus was observed during all treatments. Most profound reduction was found during treatment with two TTS scopolamine. The vestibular part was reduced by treatment with two TTS scopolamine, only. The results indicate that scopolamine and dimenhydrinate exert their effect in motion sickness by reducing the vestibular and visual influx and by partly inhibiting the integrative functioning of the vestibular nuclei. In their action, the motion sickness drugs seem to assist the cerebellum by diminishing impulses from various orientation reflexes in order to preserve the functional capacity of the central nervous system. Different symptoms in motion sickness seem to arise when the vestibular gain operates beyond the normal range of the cerebellar control mechanisms.
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| 9. |
- Pyykkö, I., et al.
(författare)
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Effect of proprioceptor stimulation on postural stability in patients with peripheral or central vestibular lesion
- 1991
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Ingår i: Acta Oto-Laryngologica. - 0001-6489. ; 111:1, s. 27-35
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Tidskriftsartikel (refereegranskat)abstract
- Body sway in upright stance at rest and after inducing proprioceptor stimulation, elicited by vibration applied to the calf or neck muscles, was studied in 11 patients with peripheral lesion and in 17 patients with central vestibular lesion. The responses were compared with those of 20 normal subjects. Vibratory stimulus was applied at five different frequencies, ranging from 32 to 150 Hz, and at a constant amplitude of 2.1 mm. Postural stability was measured with a force platform in terms of average deviation of body position (ADBP) analyzed in relation to the individual maximum support distance in the anterio-posterior direction. In patients with peripheral vestibular lesion ADBP was moderately increased, compared to normal subjects, when the calf muscles were exposed to vibration under eyes closed conditions (i.e. no visual information available); stimulation of neck muscles both under eyes open and eyes closed conditions and stimulation of calf muscles with open eyes produced an ADBP of the same magnitude as in controls. In patients with central vestibular lesion, proprioceptor stimulation of calf and neck muscles caused increased ADBP whether with eyes open or closed. The ADBP induced by stimulation of neck muscles was significantly greater in patients with a central lesion than in those with a peripheral vestibular lesion. The results indicate that patients with peripheral lesion differ from those with central vestibular lesion in their reaction to proprioceptor stimulus; and that in patients with central vestibular lesion proprioceptor stimulation of the neck muscles produces disproportionately powerful cervico-collic reflexes.
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| 10. |
- Schalén, L, et al.
(författare)
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Effects of intravenous diazepam and thiopental on the vestibulo-ocular reflex in man
- 1989
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 108:S468, s. 9-165
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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 injection. Although both drugs were detected in blood still 8 h after the injection, there were no longer significant effects on VOR. Moreover, individual values of VOR gain and time constant did not correlate with the blood concentrations of the drugs. Decrease of VOR gain and shortening of time constant after i.v. given diazepam and thiopental in man are interpreted as resulting from both specific effects on VOR and non-specific reduction of alertness.
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