[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.

[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.

[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.

[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.

[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.

[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.

[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.

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.

[Sleep polygraphy with recording of intracranial pressure and measure of cerebral blood volume in hydrocephalic infants (author's transl)].

This study was carried with the intention of explaining the causes of modifications in intracranial pressure (ICP) during paradoxical sleep (PS) in normal and hydrocephalic infants, and establishing relationships between these modifications and cerebral blood volume (CBV). All tests (conventional sleep polygraphy, ICP measured by a transducer on the fontanel, CBV measured by isotopic labelling of red blood cells in vivo) were carried out without use of surgical procedures. During paradoxical sleep there was a sustained wave of increased intracranial pressure lasting from 10 to 20 minutes, as well as phase-type variations lasting no longer than 1 minute.

[Determination of optokinetic reactivity by a sudden supra-optimal acceleration of the stimulus (author's transl)].

The authors describe a new method of optokinetic stimulation. The stimulus is applied during 3 successive sequences: the first and third include displacement of 1 to 2 black or white bands per second (apparent mean speed of 16 degrees/sec), while the second sequence comprises the sudden acceleration of 6 black or white bands per second (apparent mean speed of 59 degrees/sec.).

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.