Biomedical subjects

C H Chouard

Publications and source records attributed to C H Chouard.

At least 19 recordsLinked to original sources

PubMed1992

Clinical results of a 15-filter digital auditory prosthesis using selective amplification and compression.

Classical hearing aid efficiency was compared with that of a 15-filter digital auditory prosthesis in 23 patients suffering from partial sensorineural hearing loss. This device contains a microprocessor 320C25 from TEXAS Instruments. The sound signal is analysed at a sampling rate of 16 kHz. With the use of a Fast Fourier Transform (FFT), it provides the system with 15 energy levels at frequencies ranging from 0 to 8 kHz. The energy of each frequency band is multiplied by a coefficient stored in the device memory and directly dependent on the patient's audiometric specificities. The 15 signals are then synthesized by inverse FFT and mixed in a loudspeaker. The prosthesis is a rechargable battery powered 4 x 10 x 15 cm box programmable through a PC. The clinical results obtained with this 15-filter digital prosthesis are discussed and compared with the performances of present classical hearing aids.

Auditory Threshold↗

PubMed1992

[Improvement of clinical results by digitalization of a single channel cochlear implant].

For 1973 we have been among the first to claim the multichannel cochlear implant superiority regarding single channel efficacy. However we actually thing that single channel cochlear implant is indispensable in case of total ossified cochlea, and very useful when efficacy/coast ratio must be considered. In order to narrow the gap between multi and single channel device efficacy, we used the new microprocessors possibilities to digitalize the analogic emietter of the single channel system, which we designed in 1987. Owing to a PC keyboard the new emietter allows the speech therapist to select the frequency band width of the input signal, and to determine the threshold level and the dynamic value as a function of six steps values of the stimulus wave frequency. These improvements supply the patient with a better speech intelligibility excepted for vowels discrimination. Comparison of clinical results obtained through the two analogic and digital systems are reported on 4 post lingually and 4 pre lingually deaf patients.

Adolescent↗

PubMed1992

[Indications and results of cochlear implants in young children].

In order to determine the criteria for patient selection and the preoperative prognostic factors for hearing recovery after cochlear implants in young totally dead children, the results of hearing rehabilitation were studied in 15 children who had undergone cochlear implantation at from 2 to 9 years of age. The choice of implant is determined by the permeability of the cochlear duct. A multi-system should be used, except when the cochlea is totally ossified. The reliability and efficacy of mono and multi system implants make it possible to offer a solution to the urgent therapeutic problems posed by total deafness in the young child.

Age Factors↗

PubMed1992

[3D imaging of the labyrinth: application to candidates for cochlear implant].

Cochlear implantation is a treatment for profound bilateral cochlear hearing loss. Two broad varieties of cochlear implants are used: single or multichannel device (22- channel) inserted either into the cochlea (tympanic ramp) or on the promontory on round window Imaging modalities have to predict cochlear patency prior surgery, an essential factor for choosing between intra or extra cochlear implant. Since March 1991, we have investigated 23 implant candidates to evaluate cochlear patency prior surgery, 6 patients underwent surgery: 4 had a multichannel and 2 had a monochannel electrode. Both CT and MRI play a role in pre operative study. CT easily predicts cochlear ossification and labyrinthine malformations MRI (3 D applications) with T 2 Weighted images, one millimeter thick, more clearly depicts labyrinthine liquid and can predict cochlear fibrosis before ossification.

Cochlear Implants↗

PubMed1991

Environmental and electrophysiological study of absolute pitch.

Absolute pitch (AP) is the ability to name a note without any reference, while relative pitch (RP) needs a previous and known tone to recognize such a note. We suggest that AP is due both to environmental impact and physiological particularity. From the responses of 263 musicians including 169 AP we observed that for AP musical environment in childhood was better, the earlier the age of instrumental beginning as compared to RP. The study of otoacustic emissions evoked by a supraliminar stimulation in 183 musicians' ears including 68 AP showed that the echo was significantly greater in cases of AP than in cases of RP.

Adolescent↗

PubMed1991

[The choice between mono- and multielectrode implants in rehabilitation of total deafness in young children].

We underline the necessity to supply a prelingually totally deaf patient with some sound information before the critical age of about 5-8 years, which we had previously experimentally demonstrated on the guinea pig. Multichannel cochlear implant is the most efficient and must be placed most of cases. However, specially in case of total ossified cochlea, single channel cochlear implant is the only usefull. The respective indications of these two different systems are discussed as a function of pronostic preoperative data, cochlear total ossification, and financial considerations. The decision to supply a young totally deaf child with a cochlear implant must be considered as an emergency.

Age Factors↗

PubMed1991

[Malignant external otitis. When and which imaging].

Malignant external otitis (MEO) is a severe infection of the external auditory canal (EAC), most often caused by Pseudomonas aeruginosa, although a few cases are caused by an Aspergillus (4). Mortality remains high (20%) in spite of an early general antibiotic treatment. This infection of the soft tissue of the EAC causes cellulitis, chondritis and osteomyelitis, and there are risks of diffusion into the base of the skull. Our work is aimed at placing computed tomography and magnetic resonance imaging into the context of exploration of this infection, in relation to radionuclide scanning, owing to our experience with 10 patients. Imaging appreciates the anatomical extension of the infection beyond the EAC and towards the base of the skull and the infratemporal fossa, this being a key element for prognosis. It assesses the efficiency and duration of treatment, although the criteria of healing are still difficult to appreciate and late recurrence is frequent. Exceptionally, it is useful for diagnosis in some particular clinical forms.

Adult↗

PubMed1991

[Presentation of a 16-filter hearing aid with selective amplification and compression].

The hearing aid device is a 4 X 10 X 15 cm box. It is battery operated and monitored by a PC computer. The Texas 320C25 microprocessor performs real-time signal analysis at 16 kHz and gives 16 energy levels ranging from 0 to 8 kHz by Fourier transform. For each frequency band, the energy received is multiplied by a gain determined according to the patient's audiometric characteristics stored in the device's memory. The signal is then synthesized by reverse Fourier transform and sent to the earphone. The performances of this device are discussed and compared with present hearing aid devices.

Amplifiers, Electronic↗

PubMed1991

[Laterality and ORL pathology].

Cerebral dominance anomalies or lefthanded percentage are significantly increased in case of allergy or other immunological diseases, in dyslexia and stuttering. ENT is particularly interested in this association which has been described and explained by Geschwind and Galaburda, because immunological components of chronic rhinopharyngitis must be specially suspected on a young lefthanded child, and because dichotic tests may presently easily performed.

Animals↗

PubMed1991

[Contribution to the study of laterality in professional musicians].

Left-handed professional musicians percentage is not significantly different from normal population, excepted for piano, organ and harpsichord players. For these instruments the melody is always written for the right hand, probably because of the location of the frequencies which are the most easily perceived by the human ear on the right part of the keyboard. Thus for a lefthanded musician to play piano is comparable to write with his right hand, and as a consequence leads him to play an other instrument for his professional activity.

Dominance, Cerebral↗

PubMed1990

[Mechanisms and physiologic role of yawning].

As well as being present in all mammals, yawning occurs, at least in its mandibular component, in all vertebrates. The existence of pathological and pharmacologically induced yawning justifies study of this everyday ENT reflex. Its mechanism remains uncertain. The most likely hypothesis would seem to be stimulation of the reticular system of the brain-stem by signals originating in masseteric neuromuscular spindles sensitive to stretching. Serotoninergic inhibition from the dorsal raphe, a fall in hypothalamic dopaminergic inhibitory tone, followed by ocytocinergic hippocampal activation and then more diffuse cholinergic activation of cranial nerve motor nuclei seems likely. Various hormonal or socio-environmental influences can modify the activity of these different systems. The physiological consequences and the communicative value of yawning become more diversified with the phylogenetic evolution of the subject. Yawning appears to correspond to an alertness reflex which has acquired a paralinguistic value with evolution and may have a role in protection or social cohesion.

Animals↗

PubMed1990

[Contribution to the study of the perfect pitch].

Absolute pitch (AP) is the ability to name a note without any reference, since relative pitch (RP) needs for a previous and known tone to be able of such a recognition. We suggest that AP is due to both environmental features and physiological particularity. From the responses of 263 musicians including 169 AP we observed that for AP musical environment in childhood was better, and younger the age of instrumental beginning than for RP. The study of otoacustic emissions evoked by a supraliminar stimulation in 183 musicians ears including 68 AP showed that the echo was significantly greater in case of AP than in case of RP.

Adult↗

PubMed1990

[Presentation of the prototype of a fully implanted cochlear prosthesis].

Description of the prototype of a fully implanted cochlear implant demonstrating the feasibility of a prosthesis with no external component within the next few years. The battery is reloaded by means of electromagnetic induction, and the sound message is received by a subcutaneous microphone, which already has a satisfactory bandwitch and signal-to-noise ratio. This system can be generally applied to most types of permanent intracorporeal stimulation.

Cochlear Implants↗

PubMed1990

["Monosonic" one canal digital implant].

In order to decrease the gap between the single and multichannel cochlear implant efficacy we tried to improve the speech coding strategy of the Monomac, the constant current single channel system which we designed in 1987. Owing to a research computerized system, different strategies have been successively studied in the laboratory on 12 new implanted patients during the first weeks of the post-operative period to avoid habituation differences. Results led us to design a miniaturized digital emitter, the Monosonic. This emitter allows the speech therapist to program the frequency band wideness (80-1000 Hz) of the transmitted information, and the threshold level and dynamic range of the stimulating square wave as a function of its frequency. Other strategies are discussed, which have not been yet studied, but may be also programmed.

Acoustic Stimulation↗

PubMed1990

[Presentation of a French language protocol for the evaluation of communication improvement in the deaf following implantation].

We have been led to drawing up a procedure of assessment of communication as restored by implantation. This procedure is simple, and can be used by all teams, however complex the material implanted is. It can be implemented for children as well as adults, and for both pre- and post-speech deafness. Our staging allows integrating the implanted patient into the classical description of deafness, while retaining the specific features of electrical stimulation.

Auditory Perception↗

PubMed1990

[Results and indications of cochlear implant in 19 cases of total pre-speech deafness].

From June, 1987, to January, 1900, 19 patients aged 3 to 56 years have been rehabilitated for total deafness occurring prior to the acquisition of speech, ie. before age 2, whatever its cause. Some degree of hearing was achieved in all cases. However, the rate and steadiness of progress in auditory recognition, the daily period of use of the device and the changes in the behavior were inversely proportional to the patient's age. This leads to proposing cochlear implants for all patients, especially children, and all the more largely as they are young.

Adolescent↗

PubMed1990

[Clinical results of the surgical treatment of 1222 cases of chronic snoring].

Uvulopalatoplasty was performed (whether or not associated with tonsillectomy and/or septoplasty) in 1,222 cases of chronic rhonchopathy. Among them, 65 cases consisted of pre- and postoperatively registered sleep apnea syndrome. Clinical results were assessed on improvement of preoperative snoring, apneas, morning asthenia, daily sleepiness. Surgery was totally successful in 50% of cases, partially in 35%. Failure was encountered in 15% of cases. Failure or partial improvement are related to the preoperative presence of one or several of five particular risk factors: neck shortness, tongue hypertrophia, retrognathia, obesity and nasal pathology. Surgical complications were rare. Severe rhinolalia occurred in five cases: only three of them were sufficiently to accept plastic reconstruction which was successful.

Adult↗

PubMed1990

[Physiopathologic value of cephalometric teleradiography study and magnetic resonance imaging in sleep apnea syndromes. Therapeutic deductions].

A cephalometric study was carried out on 98 patients assigned to 3 groups including 48 patients with sleep apnea, 25 patients with chronic rhonchopathy without apnea, and 25 controls, respectively. 44 patients benefited from lateral teleroentgenographic investigations and 54 had sagittal-median NMR sections visualized. Various distance, angle and area measurements were obtained. The authors found that anomalies were the more severe that snoring was associated with sleep apnea. These arguments speak for an evolutional character of the disease. The various cephalometric anomalies were primarily related to the hyoglossal apparatus, more rarely to the maxillary-mandibular basal bones. After this analysis, the authors propose a therapeutic strategy for the management of chronic snoring associated with sleep apnea.

Cephalometry↗