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A Uziel

Publications and source records attributed to A Uziel.

At least 19 recordsLinked to original sources
PubMed2000

Synchrony generation in recurrent networks with frequency-dependent synapses.

Throughout the neocortex, groups of neurons have been found to fire synchronously on the time scale of several milliseconds. This near coincident firing of neurons could coordinate the multifaceted information of different features of a stimulus. The mechanisms of generating such synchrony are not clear. We simulated the activity of a population of excitatory and inhibitory neurons randomly interconnected into a recurrent network via synapses that display temporal dynamics in their transmission; surprisingly, we found a behavior of the network where action potential activity spontaneously self-organized to produce highly synchronous bursts involving virtually the entire network. These population bursts were also triggered by stimuli to the network in an all-or-none manner. We found that the particular intensities of the external stimulus to specific neurons were crucial to evoke population bursts. This topographic sensitivity therefore depends on the spectrum of basal discharge rates across the population and not on the anatomical individuality of the neurons, because this was random. These results suggest that networks in which neurons are even randomly interconnected via frequency-dependent synapses could exhibit a novel form of reflex response that is sensitive to the nature of the stimulus as well as the background spontaneous activity.

Action Potentials↗
PubMed2000

Benefits of cochlear implantation in elderly patients.

Cochlear implantation in elderly patients is a questionable subject. The purpose of this study was to evaluate the procedure and its outcome, the postoperative course, and the audiologic and social benefits of cochlear implantation in this population. Twenty-seven patients older than 60 years were compared with a control group of 15 adult patients. This retrospective study analyzed data concerning the outcome of the procedure, postoperative course, postoperative orthophonic test results, and answers of a questionnaire assessing the changes in communication, perception, and social outcomes. The procedure was uneventful in both groups. Minor complications were not more frequent in elderly patients. Orthophonic test results were comparable in both groups. At 12 months, 83% of the elderly patients had an open-set speech discrimination score above 60%. The benefits of cochlear implantation in terms of the quality of life are not statistically different with younger patients. Cost-utility analysis might support these findings.

Adult↗
PubMed1999

Cochlear effects of mesna application into the middle ear.

Mesna (sodium 2-mercapto-ethane sulphonate) belongs to a class of thiol compounds that produce mucolysis by disrupting the disulphide bonds of the mucus polypeptide chains. The registered indications of mesna include the treatment of pathologies of the respiratory tract and, in oncology, the prevention of toxic lesions of the urinary tract by antineoplastic agents. In the E.N.T. Clinic of the University of Parma, it has been found that mesna can be used to facilitate the dissection of the various tissue layers in any surgical procedure. One of these indications is surgical treatment of cholesteatoma, which is mainly composed by keratin, a protein rich is disulphide bonds that are easily disrupted by mesna. The aim of this study was to evaluate the toxicity of mesna application into the middle ear on the cochlear anatomy and physiology. Three groups of guinea pigs were used as subjects. Mesna solution (10 or 20%) was applied in one ear, while the opposite ear received a placebo (saline solution). Toxicity of mesna was assessed by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), and auditory brain-stem response (ABR). TEM and SEM did not show any toxic effect on cochlear morphology. There were no differences in ABR thresholds and wave III amplitude and latency between mesna-treated and control ears.

Animals↗
PubMed1999

[The test for the evaluation speech perception and production].

The aim of this paper is to present a Test to evaluate the speech perception and production in french profoundly hearing impaired children fitted with cochlear implant or traditional hearing aids. This test materials have been developed for children from 2 to 10 years old. This test fall into two basic categories known as speech perception and speech production. The assessment of the perceptual abilities through the use of the TEPPP is achieved across the hierarchy of perception which spans: detection, discrimination, identification, comprehension. The assessment of the speech production makes it possible to observe the speech production changes across three levels: phonetical, linguistical, intelligibility. The TEPPP, Test of Speech Perception and Production evaluation, enable us to observe if children, who receive a cochlear implant or a conventional hearing aids, obtain some degree of benefit in both speech perception and speech production.

Child↗
PubMed1998

Influence of communication mode on speech intelligibility and syntactic structure of sentences in profoundly hearing impaired French children implanted between 5 and 9 years of age.

OBJECTIVE: The purpose of this study was to examine the speech production in French profoundly hearing impaired children, focusing on word intelligibility, sentences syntax, and sentence pattern stages, by incorporating direct comparisons between speech production skills and communication modes in the same children. DESIGN: The design of the study incorporated a within-subject, repeated measures design for assessing speech production intelligibility and syntax. SETTING: Montpellier Pediatric Cochlear Implant Center. SUBJECTS: Twelve prelingually deafened French children who received a Nucleus multichannel cochlear implant (mean age at the time of implantation was 7 years 2 months) served as subjects for the speech production assessment. MAIN OUTCOME MEASURES: Speech production intelligibility, syntax, and sentence pattern stages were assessed at 1, 2 and 3 years postimplant. Speech production skills were related to the communication mode of the children (auditory-oral, four children; cued-speech, four children; sign-language, four children). RESULTS: Scores on word intelligibility steadily improved with increased experience with the implant, ranging from 18% before implantation to 54.5% at 36 months postimplantation in the overall population. The highest scores were found in the cued-speech group with an averaged score of 66.8% at 36 months postimplant. The number of syntactic elements increased over time with implant experience. Children receiving cued-speech education had higher scores by 3 years postimplantation than children receiving either auditory-oral or sign-language modes of communication. Language level (sentence pattern stages) also improved with increased experience with the device. By 3 years postimplantation, children receiving auditory-oral or cued-speech instruction were able to produce sentences; however, the sign-language children failed to do so at a rate comparable to the other children. Language level was significantly higher in the oralist or cued-speech educated children than in the sign-language group. CONCLUSIONS: Speech production skills improved with increased experience using a cochlear implant. Word intelligibility, syntactic structure of sentences, sentence pattern stages improved gradually over time. Production skills were greater in the cued-speech educated children group than in the auditory oral or sign-language groups. Statistically better sentence pattern stages were found in the auditory oral and sign-language groups.

Child↗
PubMed1998

Adenovirus-mediated in vivo gene transfer in guinea pig middle ear mucosa.

This article describes a study designed to assess the feasibility of using recombinant adenovirus for delivering therapeutic peptides in vivo in the guinea pig middle ear cleft. A recombinant adenoviral vector AdCMVsp1 LacZ containing the Escherichia coli beta-galactosidase was injected into the middle ear space. Qualitative assessment of cell middle ear transfection was performed on day 2 by light microscopy study, after injecting a multiplicity of infection (MOI) ranging from 0 to 1000. At an MOI of 30, 30% of the promontory area epithelial cells were stained. An MOI of 50 stained 60% of the cells and an MOI of 100 or more stained more than 90% of the cells. The duration of cell transfection was studied after injecting an MOI of 50. The percentage of stained cells was 60% on day 2, 10% on day 7, and 0% on day 14. Middle ear mucosal inflammation, consisting of a granulocytic infiltrate, was observed when an MOI above 50 was used. Even at a high MOI (500), no staining could be found in the cochlea, in the facial nerve, in the brain, or in visceral organs. These data suggest that recombinant adenovirus vectors can be used to transfer genes in the middle ear. This method appears to be safe, and may be envisaged as a short-duration treatment to transfer genes in vivo in the treatment of middle ear diseases.

Adenoviridae↗
PubMed1998

[Chemical labyrinthectomy: results and applications].

GOAL OF THE STUDY: Unilateral Menière's disease can be treated by chemical labyrinthectomy. The goal of this work was to report our clinical experience with chemical labyrinthectomy, and to discuss the respective value of labyrinthectomy and of vestibular neurotomy for treating unilateral Menière's disease. METHODS: Twelve patients underwent chemical labyrinthectomy using middle ear gentamicin infusion. Before treatment, patients had a pure tone audiogram and a vestibular caloric testing. After treatment, patients had a clinical assessment at 1 and 6 months after treatment (pure-tone audiogram, vestibular caloric testing), and answered a questionnaire at 1 and 2 years following the treatment (number of vertigo attacks, ataxia, tinnitus, subjective assessment of the method by the patient). RESULTS: At two years post-treatment, the vertigo cure rate was 91.6% (ABC using AAOO criteria), vestibular function was abolished in 70% of cases, ataxia was reported in 42% of patients, 16.6% of patients had hearing deterioration above 20 dB HL (C following AAOO criteria), tinnitus was decreased in 50% of cases. Of 12 patients, 8 were satisfied. CONCLUSION: Chemical labyrinthectomy cures vertigo in Menière's disease, with similar cure rate than vestibular neurotomy. Minor complications can occur with chemical labyrinthectomy. This method should be used in more patients.

Adult↗
PubMed1997

Speech perception skills and speech production intelligibility in French children with prelingual deafness and cochlear implants.

OBJECTIVE: To examine speech perception and production intelligibility in French children with prelingual deafness who received multichannel cochlear implants. DESIGN: Within-subject, repeated-measures design for assessing speech perception and a cross-sectional design for assessing overall speech intelligibility. SETTING: A pediatric cochlear implant center. SUBJECTS: Sixty-four French children with prelingual deafness who received multichannel cochlear implants (mean age at time of implantation, 3 years 11 months) underwent assessment for speech perception. A subset of 16 children who received implants by 3 years of age underwent assessment for speech intelligibility. MAIN OUTCOME MEASURES: Speech perception skills were assessed using phoneme detection, closed-set word and sentence recognition, and modified open-set (MOS) recognition. Speech intelligibility was assessed by asking 50 listeners to identify recorded speech samples from the subjects. Dependent variables for the studies consisted of percent of correct items. RESULTS: After implantation, all children were able to detect phonemes by 3 months. Closed-set word and sentence identification reached 100% accuracy by 48 months (7 children with 4 years of implantation experience). Some children (8 of 48) demonstrated some MOS recognition after 1 year. Modified open-set recognition averaged 67.9% by 42 months (12 children available) and 80% by 48 months (7 children available). Overall speech intelligibility was 4.2% after 1 year, 30.7% after 2 years, 55.2% after 3 years, and 74.2% after 4 years. Within-subject comparison of MOS recognition and overall speech intelligibility scores revealed an insignificant trend for high perceptual performance to be associated with higher speech intelligibility scores (P = .17). There also was a tendency for higher performance to be associated with longer implantation experience. CONCLUSIONS: Speech perception scores appear to increase with increased experience using a cochlear implant. Overall speech intelligibility appears to steadily improve with increased experience and appears to be poorly related to perceptual performance on MOS recognition tasks.

Child, Preschool↗
PubMed1997

Monitoring eustachian tube opening: preliminary results in normal subjects.

Sonometry studies the changes of sound intensities induced by the eustachian tube opening in the external meatus when a constant sound is applied in the nasal cavity. The function of the eustachian tube is not disturbed by the test procedure. An original portable device with a high signal-to-noise ratio has been developed in our lab. This device was able to detect a 6-dB sound pressure level (SPL) signal in a 100-dB SPL noise. Long-duration recordings of auditory tubal openings could be performed. This work presents the data found in normal subjects. One hundred twenty healthy ears were recorded. Eustachian tube openings were detected in 62.5% of the cases. Of the 1777 openings recorded, the average opening duration was 430 ms +/- 183 ms. The average number of eustachian tube openings was 21.7+/-16.4 (for 15 minutes). All swallowing did not necessary open the eustachian tube. This work shows that this new device allows long-duration recording of eustachian tube function in everyday life conditions.

Acoustic Stimulation↗
PubMed1997

Selection criteria for cochlear implants in children.

OBJECTIVE: To determine the selection criteria for cochlear implantation in children. SETTING: Hospital pediatric implant center. PATIENTS AND INTERVENTIONS: Selection of patients depends on medical evaluation, audiometric data, speech discrimination, communication skills, cognitive skills, and psychosocial factors. Patient selection is based on tonal audiometry, computed tomography, magnetic resonance imaging, and electrophysiologic tests. Side of implantation is chosen according to cochlear structure, duration of deafness, and dominant handedness. RESULTS: Ninety-eight cochlear implantations with the Nucleus multichannel implant have been performed at this center since 1990. CONCLUSION: The selection of children for cochlear implantation require close collaboration between the pediatric surgical team, the educational team, and the family.

Auditory Threshold↗
PubMed1996

Electrical stimulation activates two different sites within the guinea pig cochlea.

This study investigates whether auditory brainstem responses (ABRs) can be used to assess the functioning of electrically stimulated cochleas. Electrically evoked auditory brainstem responses (EABRs) were recorded in guinea pigs with normal hearing and guinea pigs deafened by amikacin, a powerful ototoxic antibiotic, combined with diuretic aminooxyacetic acid (AOAA). Two different types of EABRs were observed in normal animals, depending on the electrical pulse intensity applied to the round window: long-latency brainstem responses were evoked by low stimulation intensities, short-latency brainstem responses by high intensities. The absence of effect of strychnine applied intracochlearly ruled out the possibility of medial efferents being involved in these responses. Conversely, an intracochlear application of tetrodotoxin (TTX), an Na(+)-channel blocker, resulted in the disappearance of both types of responses, attesting that the sites activated by the electrical stimulation were located within the cochlea. In AOAA/ amikacin poisoned cochleas, in which most of the hair cells were missing with apparently normal ganglion neurons, the long-latency brainstem responses evoked by low intensities were completely lacking. These findings suggest that low currents applied to the round window of the guinea pig cochlea primarily activate the hair cells, the neurons being directly excited at higher intensities.

Acoustic Stimulation↗
PubMed1996

[Aberrant intra-petrous internal carotid artery: apropos of a case].

This article illustrates a case of an aberrant pathway of the petrous portion of an internal carotid artery presenting as a cholesteatoma. This is a case of a 53 y.o man presenting with unilateral otalgia and vertigo. Otoscopic examination revealed a whitish retro-tympanic mass accompanied by a conduction hearing loss mimicking a cholesteatoma. An exploratory tympanotomy was performed. The surgical procedure was interrupted after needle aspiration of the mass suggesting an aberrant course of the petrous portion of the internal carotid artery. Authors report a review of the literature with an emphasis on the differential diagnosis, clinical and paraclinical diagnostic work-up. A thorough knowledge of this anomaly is required to avoid an iatrogenic risk during any otological surgery.

Carotid Artery, Internal↗
PubMed1995

Tympanic membrane regeneration and growth factors.

Recent experiments have shown the healing potential of growth factors in tissue repair. Epidermal interference and fibroblast growth factors in the healing of acute and chronic tympanic membrane perforations are reviewed and discussed.

Acute Disease↗
PubMed1995

Criteria for selecting the side for cochlear implantation.

Choice of the side for cochlear implantation should take into account peripheral (extracortical) factors and central (cerebral dominance) factors. From 111 patients implanted with a Nucleus device, the authors found that significant peripheral factors were the degree of cochlear ossification, the duration of deafness before cochlear implantation, and the preoperative promontory test dynamic range (degree of response on the promontory test in decibels); cause of deafness and residual hearing were not correlated with speech discrimination. Cerebral dominance was indirectly determined by handedness. Handedness laterality was determined by a questionnaire. There was no significant difference in results between patients implanted on their dominant side and patients implanted on their nondominant side. When ears are different according to their peripheral factors, the authors suggest implanting the better ear, provided there is no significant hearing in that ear. When both ears are identical, the side of implantation should be the side of handedness laterality to facilitate device manipulation (a practical reason).

Adolescent↗
PubMed1993

Intraoperative facial nerve monitoring in posterior fossa acoustic neuroma surgery.

Intraoperative facial nerve monitoring has become an indispensable tool during cerebellopontine angle surgery. Ninety-seven patients underwent surgical removal of an acoustic neurinoma with the use of a pneumatic sensor monitoring between January 1, 1986, and December 31, 1990. In the early postoperative period, a normal or near-normal facial function (grades I and II) was achieved in 86% of the patients, a moderate dysfunction (grade III) was present in 7%, and a total or severe dysfunction (grades V or VI) was present in 6%. Normal function at 1 year was achieved in 90.5% of the patients, 4% were grade II, a moderate dysfunction (grade III) was present in 2%, and 3% showed a total or severe dysfunction (grade V and VI). The incidence of normal function decreased with tumor size, with an occurrence rate of 100%, 94%, and 91% in small, medium, and large tumors, respectively. In eight consecutive patients, all responses detected by the monitoring during the operation were collected and analyzed according to intraoperative events. Analysis of the results indicate that 95% of the 316 mechanically induced stimulations were of small or extremely small amplitude, and only 5% were of moderate amplitude. A medial-to-lateral strategy of dissection, preservation of the arachnoid veil over the facial nerve, a control by the monitoring of the amount of traction, and a more widespread use of sharp dissection were the major approaches to reduce surgical trauma during dissection.

Adult↗
PubMed1993

[Surgical technique and results of cochlear implant in normal or ossified cochlea].

The authors describe the surgical technique and results of the Nucleus device in 50 recipients. Cochlear ossification was present in one third of patients. Total insertion was possible in all cases with a partial ossification (< or = 8 mm), and once in a case with a total ossification (> 8 mm) of the scala tympani of the basal turn. Results were not significatively different in normal cochleas and in ossified cochleas. The authors describe a per-operative algorithm in front of a basal turn ossification, emphasizing on the insertion in scala vestibuli through the oval window. According to the results, the authors prefer the use of a multi-channel cochlear implant than a monochannel implant, even in ossified cochleas.

Adolescent↗