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Biomedical subjects

V Gabersek

Publications and source records attributed to V Gabersek.

At least 19 recordsLinked to original sources
PubMed1990

[Electrophysiologic studies in patients with cochlear implants].

The insertion of reliable extracochlear single-canal cochlear implants in cophotic and subcophotic patients allows the electrical stimulation of the acoustic nerve for rehabilitation, as well as audiovestibular explorations that are no longer possible in the acoustic mode. The authors therefore aim at replacing all these examinations with their Electrical equivalent: --early evoked potentials (E-BERA), --medium-latency evoked potentials (E-MLR), --Event-related evoked potentials (E-P300), for which, to our knowledge, theses are the first recordings, --electrical stapedial reflex, --vestibular stimulations. The method, results and clinical and physiological applications of each method are given, as well as its prospects.

Acoustic Stimulation↗
PubMed1985

[Improvement in evoked vestibular responses by tubular vision].

Numerous factors can influence evoked or spontaneous nystagmus. In this study, the influence of reducing the visual field to a peripheral field of 18 degrees 40' was investigated in 15 subjects with normal vision. In order to reproduce the conditions of photoelectric recording with Torok's glasses, a tube was placed in front of one eye while the other eye was covered. This resulted in the enhancement of the evoked vestibular and optovestibular responses and the reduction of the subjective sensations of the subject, suggesting that the tubular vision might be helpful for the study of cinetosis. Our study also showed two culminating points and two critical phases in caloric nystagmus.

Adult↗
PubMed1983

[Voluntary and reflex oblique ocular movements in cranial injuries].

In a population of 241 head injuries, some of which dated prior to 3 months and others after, the modalities of graphic responses to an oblique stimulation are described (optokinetic test and ocular calibration). In fact, the distribution of the various types of graphic responses differ statistically depending on the age of the injury. In injuries less than 3 months old a majority of oblique ocular responses were found to be of the intermediate type, while in those with injuries of more than 3 months ago, the oblique ocular responses of a rotary type predominated. However, above all the results of the video recording used to visualize the ocular responses, which until now have been presented graphically, will be discussed.

Adolescent↗
PubMed1983

[Comparative study of the electronystagmographic changes in multiple sclerosis and neuroallergies].

Electronystagmographic (ENG) recordings were compared in patients with multiple sclerosis (30 cases) or with an allergic diathesis (100 cases) presenting, in addition to other symptoms, disturbances in balance and vertigo. The ENG examination included: study of voluntary 10 degrees ocular movements and spontaneous ocular signs, the blinking test and pendulum tracking test, the optokinetic reactivity test, the damped pendulum giration test, and thermal tests. Absence or desynchronization of the subjective sensation of giration in relation to the true movement of the armchair was noted during the damped pendulum giration test. Optokinetic reactivity was indicative of possible optokinetic recruitment. Multiple sclerosis patients showed a higher frequency of bilateral vestibular hyperreflectivity in the thermal test whereas peripheral hypovalence was more common in allergic patients. Overall alterations were generally more marked and more stable in multiple sclerosis, more labile forms being observed in neuro-allergies. It is suggested that the mechanism of the inflammatory edematous reaction in the plaques could be similar to that of the angioneurotic edema observed in the neuro-allergic affection.

Adolescent↗
PubMed1982

[Physiological ocular incongruity in man (author's transl)].

Ocular incongruity is not always symptomatic of pathology: it is sometimes simply found among the many physiological characteristics of man. The various situations which can bring about a physiological ocular incongruity are found successively during instrumental vestibular trials: incongruities in amplitude are recorded during the rapid phase of the provided nystagmus and incongruities in speed during the slow phase. These incongruities appear during the caloric responses for the homolateral eye to the irrigation and in the rotary, sinusoidal pendular test for the eye homolateral to the direction of the rapid phase of the provoked nystagmus. During a voluntary blink an ocular incongruity of direction appears as an intorsion of the two eyes. Incongruous ocular movements increase during sleep. They appear equally often during onset of sleep and during the stages comprising slow waves or paradoxical sleep. In children engaged in reading or submitted to an optokinetic test, congruity is not present at first but only occurs once the child has acquired the oculocephalic dissociation.

Adolescent↗
PubMed1981

[Optokinetic reactivity and vestibular disorders of central origin (author's transl)].

An electronystagmographic study of optokinetic reactivity is conducted in 50 'normal' adult subjects and 200 patients suffering from various diseases, all of whom presented an abnormal electronystagmogram. Optokinetic reactivity is evoked by a sudden acceleration of the optokinetic stimulus. It is considered normal when this acceleration leads to an increase in amplitude. At the same time, the frequency of the optokinetic nystagmus decreases. This type of response can be modified by various disorders. Recent cranial trauma and tetany are associated with an incomplete or inadequate optokinetic response; brain vascular diseases and disorders of central origin induce an absence of that response, while some cases of multiple sclerosis and neuro-allergies give rise to an apparently momentary, unstable response. Optokinetic reactivity thus represents an extension of the classical optokinetic test and yields valuable diagnostic clues.

Adult↗
PubMed1981

[Ocular scanning modalities in dyslexic children (author's transl)].

Voluntary and reflex ocular scanning has been investigated in 55 dyslexic children, aged from 8 to 14 years 3 months, by means of potentiometric electrooculography with multiple monocular electrodes. Results are expressed in terms of amplitude, frequency, shape of movements and ocular congruence. A comparison between the oculomotor behaviour of dyslexic and normal children with no reading problem shows the same types of ocular movements as observed in normal schoolchildren, but they differ in their distribution according to age. Moreover, the evolution of oblique movements, described in normal children and correlated with the degree of schooling, is not the same in dyslexic children, where it instead seems to follow particular patterns. Finally, in stereotyped ocular scanning simulating reading movements, the dyslexics are characterized by the absence of two important stages leading to ocular congruence: scanning with random alternate monocular predominance and scanning with selected alternate monocular predominance.

Adolescent↗
PubMed1980

Vasomotor origin of intracranial pressure waves in hydrocephalic infants.

By measuring cerebral blood volume (CBV) and intracranial pressure (ICP) variations at the same running time during sleep, it has been demonstrated that the ICP wave which appears during the REM sleep in hydrocephalic infants is produced by intracerebral vaso-dilatation. Nine infants with stabilized hydrocephalus were investigated by non-invasive means: REM phases were distinguished with the usual polysomnographic electrodes. Intracranial pressure was measured with a fontanel palpation transducer and CBV variations were obtained by recording 99mTc activity at the head level after in vivo labelling of red cells with 99mTc--pertechnetate. The time-activity curves, obtained from regions of interest and selected on the sequential radioisotope images, show that an increased ICP wave, occurring during the REM period, is related to a simultaneous increase in the blood volume, limited to the cerebral sector and not to the area of the external carotid artery.

Blood Volume↗
PubMed1976

Intracranial pressure and rapid eye movement sleep in hydrocephalus.

Intracranial pressure (ICP) was monitored for 24 h in 30 hydrocephalic patients (21 infants, 9 children) representing borderline cases. The need for surgery was uncertain because their hydrocephalus seemed to be more or less arrested. In 13 cases an electroencephalogram, an electro-oculogram, an electromyogram and an actogram were simultaneously recorded. During sleep related to a period of rapid eye movement (REM) fairly regular steep-rising waves of raised ICP recurred every 50-75 min, decreasing slowly to previous levels in 25-40 min. No concomitant clinical symptoms were exhibited. The cerebral pulse wave amplitude increase during REM sleep, but might vary during one period of REM sleep. The relationship between these raised ICP waves and an increase in cerebral blood flow occurring during REM sleep is studied.

Child, Preschool↗