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Biomedical subjects

A Uziel

Publications and source records attributed to A Uziel.

At least 55 records · Page 3Linked to original sources
PubMed1989

[Application of an immunofluorescent technique on a guinea pig cochlear section for the study of endocochlear pathologies].

Experimental evidence suggests the existence of autoimmune mechanisms in the appearance of cochlear pathologies. Following a recall of studies made previously by different authors, we will present an immunofluorescent technique on a guinea pig cochlear section applied to the study of 22 serums of patients with endocochlear pathologies. The goal of this test is to identify the patients with immunologic disorders in order to adapt treatment using immunosuppressive medication. The findings show the existence of antibodies directed against the cell nuclei, or against the endothelium of the cochlear vessels, or against the endosteum of the inner ear. The importance of these findings has yet to be established.

Animals↗
PubMed1988

Screening for auditory dysfunction in infants by evoked oto-acoustic emissions.

Auditory threshold using auditory brain-stem responses (ABR) was determined in 30 ears from normally-hearing infants and 16 ears from infants with sensorineural deafness. In the same population, evoked oto-acoustic emissions (EOAEs) in response to a click of 20-dB hearing level were recorded. The presence of EOAEs was correlated with ABR thresholds. Evoked oto-acoustic emissions were always present when ABR wave V threshold was equal to or below 30-dB hearing level. On the contrary, infants with ABR thresholds higher than 40-dB hearing level never had EOAEs. As the recordings of EOAEs could be obtained more rapidly than ABR thresholds (average duration: five minutes vs 40 minutes), EOAEs could hold some promise as an objective, easy, and noninvasive test for screening auditory dysfunction in infants.

Brain Stem↗
PubMed1988

A correlative study of evoked otoacoustic emission properties and audiometric thresholds.

Correlations were made between the detection thresholds of evoked otoacoustic emissions (EOAEs), subjective click thresholds, and mean audiometric thresholds in 240 normal and hearing-impaired ears. EOAEs have never been observed when subjective click thresholds or mean audiometric thresholds were equal to or greater than 35 dB HL. EOAEs were always found when click thresholds were equal to or lower than 15 dB HL and when mean audiometric thresholds were equal to or lower than 22 dB HL. The incidence of EOAEs decreased and EOAE thresholds increased with increasing click or mean audiometric thresholds.

Adolescent↗
PubMed1988

Evoked otoacoustic emissions: a fundamental and clinical survey.

Evoked otoacoustic emissions (EOAEs) hold some promise as a fast, objective and noninvasive procedure to study the cochlea at the outer hair cell level. This paper summarizes the fundamental aspects of EOAEs, in particular their relationship with the active biomechanical properties of the cochlea. The properties of EOAEs are analyzed in normally hearing ears, in ears with sensorineural hearing loss, especially in Ménière's disease, in acoustic neuromas and in central deafness; the properties of EOAEs were also evaluated as to their suitability for screening auditory dysfunction in infants.

Adult↗
PubMed1988

Evoked otoacoustic emissions: normative data and presbycusis.

Evoked acoustic emission (EAEs) recordings hold some promise as a fast, objective and non-invasive audiological procedure to study the cochlea at the outer hair cell (OHC) level. However, accurate interpretation in the EAE response must be based on a knowledge of its variations with age. In order to investigate age-related changes of EAEs, the properties of EAEs (incidence, threshold and spectrum) were studied in 151 ears from subjects whose age varied between 2 and 88 years. EAEs were present in 100% of the tested subjects until the age of 60 years. After this age, EAE incidence fell to 35%. EAE threshold did not vary until the age of 40 years but increased linearly after this age. Thus, complementary information on OHC degenerative changes in presbycusis could be deduced from these data.

Acoustic Stimulation↗
PubMed1988

[Neurinoma of the vagus nerve, contralateral peripheral facial paralysis].

A right facial paralysis led to the discovery of a tumor on the left side of the medulla oblongata. A neurinoma was suspected on MRI and confirmed by surgery and pathological examination. Ultrasonic aspiration was on interest in this case. The mechanism of the facial paralysis is uncertain: ischemia, compression and pure coincidence may be considered.

Adult↗
PubMed1988

Evoked otoacoustic emissions in patients with acoustic neuromas.

Click-evoked otoacoustic emissions were recorded in 28 patients with surgically proven acoustic neuromas and 22 patients with brain stem pathologic disorders. Data collected in acoustic tumor ears were compared with those obtained in 30 nontumor ears demonstrating sensorineural hearing losses. Acoustic emissions were altered (increased detection-threshold or no detectable emissions) in all ears with eighth nerve tumors and were not affected in those with brain stem pathologic conditions that do not involve cochlear function. The properties of acoustic emissions were similar in both tumor and nontumor ears with hearing loss, which suggests that acoustic tumors usually produce a cochlear hearing loss.

Adult↗
PubMed1988

[Contribution of cochlear acoustic emissions in pediatric audiology].

A new method is described for pediatric otologic exploration : cochlear acoustic emissions (CAE), and results reported of CAE recordings in 15 children with normal hearing and 31 infants at otoneurologic risk, suspected of having moderate or severe hypoacusia on conventional audiometry. Results were compared with those obtained by study of V wave threshold of AEP. The incidence of CAE in children and infants with normal hearing was 100%, the absence of CAE being related to a V ware threshold of AEP of 30 dB nHL or more. The CAE threshold is closely related to that of the V wave of AEP. The use of CAE, a rapid, non-invasive, objective audiometric method, could be a first line screening technic allowing separation, within several minutes, of a normal hearing population from one with a lesion of transmission or endocochlear apparatus with CAE V wave threshold of over 30 dB nHL. In addition, in children with a flat AEP the CAE allows study of the cochlear independently of auditory pathways.

Adolescent↗
PubMed1987

Correlative development of cochlear action potential sensitivity, latency, and frequency selectivity.

The present study was undertaken in order to study the rate of maturation of the cochlear action potential sensitivity, latency, and tuning curves for various stimulus frequencies and to correlate the development of latency and frequency selectivity with threshold development. This study showed a two-stage model of maturation in which thresholds and latencies declined rapidly and linearly during the first stage, and slowly and exponentially during the last stage. These results suggest that latencies and thresholds are influenced by similar maturational processes. The correlative study of frequency selectivity and thresholds showed a linear relationship during the period of rapid maturation, and conversely, a dissociation between the development of tuning and threshold during the late period of slow acquisition of adult sensitivity. This dissociation was particularly marked at 8 kHz where Q10 values continued to increase even when thresholds were adultlike. These results were discussed in relation to anatomical and functional data available from the rat cochlea.

Age Factors↗
PubMed1987

Dose-dependent changes in the rat cochlea following aminoglycoside intoxication. I. Physiological study.

The dose-dependent effects of amikacin on the rat cochlea were studied electrophysiologically using CAP audiograms, amplitude and latency-intensity curves, and CAP tuning curves using a forward masking procedure. The animals were given a daily subcutaneous injection of amikacin in doses ranging from 100 to 1000 mg/kg, for five consecutive days, and were tested one month after the end of the treatment. No functional evidence of ototoxicity was found in animals treated with 100 and 200 mg/kg per day doses of amikacin. The first electrophysiological changes were observed with doses of 300-600 mg/kg per day. They consisted of a broadening of the tip and a hypersensitivity of the tail of the CAP tuning curves, without a change in the CAP threshold sensitivity and latency. Animals treated with 700 mg of amikacin showed an elevation of the tip of the CAP tuning curves and an increase in CAP latency. The classical feature of antibiotic ototoxicity was observed in animals given 800 mg/kg per day of amikacin with an increase in CAP threshold sensitivity and latency, a disruption of the CAP amplitude-intensity function, and a clear hyposensitivity of the CAP tuning curves. These results are discussed in the light of anatomical findings described in a companion paper.

Acoustic Stimulation↗
PubMed1987

Hearing preservation after acoustic neurinoma operation.

Between 1981 and 1984, 44 patients underwent acoustic neurinoma removal by a posterior cranial fossa approach with an attempt to preserve hearing. Seven tumors were small (less than 20 mm), 28 were medium (20 to 40 mm), and 9 were large (greater than 40 mm). Preoperatively, 4 patients had normal hearing, 15 had serviceable hearing, 10 had poor hearing, and 15 had no hearing. Postoperative hearing was preserved in 11 cases. Of the 19 patients with normal or serviceable hearing, 8 (42%) had serviceable hearing preserved postoperatively. Hearing preservation was achieved in 43% of the patients with small tumors, 25% of those with medium tumors, and 11% of those with large tumors. This study confirms the value of the suboccipital approach, which can be used in an attempt to preserve hearing whenever the patient has serviceable hearing preoperatively and whenever the tumor size makes it feasible.

Adult↗
PubMed1987

[Recruitment and diplacusis. Current physiopathological concept].

The actual conception of cochlear physiology can explain the semiology of endocochlear hearing losses: mainly recruitment and diplacousis. Recruitment and diplacousis reflect lesions of outer hair cells in the cochlea. Actually, an early detection of these outer hair cells lesions may be a diagnostic priority: this seems possible with recordings of oto-acoustic emissions.

Cochlea↗
PubMed1987

[Preservation of hearing in surgery of acoustic neuroma].

Between 1981 and 1984, 44 patients underwent acoustic neuroma removal by a posterior cranial fossa approach in an attempt to preserve hearing. 7 tumors were small (less than 20 mm), 28 were medium (20 to 40 mm) and 9 large (greater than 40 mm). Of these 44 patients, 4 had normal hearing preoperatively, 15 had serviceable hearing, 10 poor hearing and 15 no hearing. Postoperative hearing was preserved in 11 cases. Of the 19 patients with normal or serviceable hearing, 8 (42%) had serviceable hearing preserved postoperatively. Hearing preservation was achieved in 43% of the cases of small tumors, 25% of those medium tumors and 11% with large tumors. This study confirms the value of the suboccipital approach, which can be used in an attempt to preserve hearing whenever the patient has serviceable hearing preoperatively and whenever the tumor size makes in feasible.

Adult↗
PubMed1987

[Oto-acoustic emissions. I. Evoked oto-emissions: a new technic of functional study of the cochlea].

Otoacoustic emissions (OAE) are sounds emitted by the cochlea and recordable in the external ear canal by a miniature microphone. These OAE reflect the existence of an active mechanism within the cochlea, probably based upon outer hair cells (OHC). Recordings of OAE are easy, noninvasive, objective and permit the exploration of an essential property of the cochlea which was impossible to study by the usual electrophysiological techniques. Clinical applications are discussed in this paper.

Adolescent↗
PubMed1986

Periods of sensitivity to thyroid hormone during the development of the organ of Corti.

Cochlear structures are sensitive to the morphogenetic effect of thyroid hormone during the whole duration of maturation. For each structure, there exists a period of maximal sensitivity to thyroid hormone which corresponds to the period of development during which the structure of interest undergoes its main morphological changes (6 to 13 days for the inner sulcus epithelium, 6 to 10 days for the pillars, the 2nd and a part of the 3rd postnatal week for OHCs and their efferent innervation in rats). These periods of sensitivity can be considered as critical periods because cochlear structures are maximally vulnerable to thyroid deficiency during these periods.

Animals↗
PubMed1986

[Possibilities of preserving hearing in the surgery of acoustic neurinoma].

Between 1981 and 1984, 44 patients underwent acoustic neurinoma removal by a posterior cranial fossa approach in an attempt to preserve hearing. 7 tumors were small (less than 20 mm), 28 were medium (20 to 40 mm) and 9 large (greater than 40 mm). Of these 44 patients, 4 had normal hearing preoperatively, 15 had serviceable hearing, 10 non-serviceable hearing and 15 anacousis. Postoperative hearing was preserved in 11 cases. Of the 19 patients with normal or serviceable hearing, 8 (42%) had serviceable hearing preserved postoperatively. Hearing preservation was achieved in 43% of small tumors, 25% of medium tumors and 11% of large tumors. This study stress the importance of the suboccipital approach which can be used in an attempt of hearing preservation whenever the patients have serviceable hearing preoperatively and whenever the tumor size makes it feasible.

Adult↗