[Laryngeal immobility after thyroidectomy]. / Immobilité laryngée post-thyroïdectomie.

One of the most common complications of surgery of the thyroid gland is vocal folds immobility. New advances in its management have been achieved over the last few years. Laryngeal electromyography, stroboscopy, and computerized analysis of the voice help guide diagnosis, allowing differentiation between recurrent nerve paralysis and glottis traumatism due to intubation, and further follow-up of recovery with relevant therapeutic decisions. In case of unilateral vocal fold paralysis, intrafold silicone or injection of autologous fat is more and more routinely used to obtain vocal rehabilitation. In case of bilateral vocal fold paralysis, to avoid tracheotomy, partial posterior cordectomy using laser surgery restores sufficient laryngeal airflow, with minimal vocal sequelae. Early management of these complications by teams of specialists should allow appropriate and less invasive surgery.

[Q.A.L.Y. index and assessment of cost efficiency of the cochlear implant in acquired profound deafness]. / Index Q.A.L.Y. et appréciation du rapport efficacité-coût de l'implant cochléaire chez l'adulte sourd profond post-lingual.

Cost utility analysis is a method of cost-effectiveness analysis which provides results in terms of cost per quality-adjusted life-year (Q.A.L.Y.). This method is progressively largely used for medical technology assessment. It permits cost-effectiveness comparisons between medical interventions. The cost per Q.A.L.Y. of cochlear implant was determined in 30 adult patients suffering from acquired profound deafness. This study indicates that this technology provides significant improvements and is quite cost-effective. However, as far as profound deafness is concerned, the reliability of Q.A.L.Y. needs to be improved.

A fractal approach to normal and pathological voices.

Using the box-counting method, we demonstrated recently that the stationary signal of vowels is not fractal, but provides the opportunity to design in the smallest scale a kind of signature for each vowel. This fractal approach to these components of speech allows us to quantify the roughness of the voice, between I (sinusoidal complex signal) and 2 (white noise). We used this method to compare these values in normal and pathological voices. We studied the speech of 10 normal speakers, 6 patients suffering from unilateral vocal fold palsy and 6 suffering from various other dysphonias. The meaning of this fractal measurement is discussed and compared with electroglottogram and spectrographic analysis.

[Cochlear implant in the aged patient]. / L'implant cochléaire chez le sujet âgé.

Despite the fact that elderly people live frequently alone and frequently have difficulties of vision, is it reasonable to refuse to supply a patient with a cochlear implant only because he is too old? We compare the results of 87 post-lingually implantees as a function of age, less than 60 years (young) and 60 years or more (old). We assessed the implant efficacy using the Protocole Francophone d'Evaluation (PFE), appreciated the speech-therapist's opinion and the patient's satisfaction, and counted the number of hours per day the implant was used (H/D). The PFE score was significantly higher in young than old. However the speech-therapist's opinion and the patient's satisfaction as well as H/D did not differ significantly in the 2 series. Elderly people are supplied with a great benefit from cochlear implants. Therefore age is not a contraindication for implantation.

[Indications for the cochlear implant in partial deafness of the adult]. / Les indications de l'implant cochléaire dans les surdités incomplètes de l'adulte.

The last (may 1995) NHI Consensus Development Conference on cochlear implant recommends to extend the use of cochlear implant for adult patient suffering from bilateral acquired severe hearing impairment. Its indications are a severe-to-profound sensorineural hearing loss bilaterally presenting an open-set sentence recognition scores less than or equal to 30 percent under best aided conditions. We report the results of our 4 first implantees responding to these criteria, and discuss the mechanisms of the speech intelligibility improvement which has been obtained.

Asynchronous interleaved stimulation (AIS): a new speech coding strategy for cochlear implant.

Cochlear implants use a fixed or F0 dependent stimulation rate, whatever the sound analysed (vowel or consonant) or procedure (fixed filters or FFT). We present a procedure which varies as a function of the input signal. This method is based on FFT analysis using a variable width analysis window. Short windows are applied on the transient part of the signal, providing poor frequency resolution but good time resolution; they permit us to accurately follow the speech signal in time during its fast temporal variations. Large windows are applied on the stationary parts of the signal, providing better frequency resolution but poor time resolution. Transient parts of the speech order this window switching; they are detected using the statistical properties of the FFT; moreover, the narrow windowing is coupled to an increase of the stimulation frequency. This strategy has been implemented using the DIGISONIC cochlear implant software, and clinically assessed in 6 regular cochlear implant users, on the basis of a consonant-vowel-consonant test. This Asynchronous-Interleaved-Stimulation (AIS) strategy provides the patients with better discrimination than fixed window FFT analysis. The coding protocol will be described and results presented.

[Asynchronous sequential stimulation. A new signal treatment for cochlear implants]. / Stimulation séquentielle asynchrone. Un nouveau traitement du signal pour les implants cochléaires.

Cochlear implants use a fixed or FO dependent stimulation rate, whatever the sound analysed (vowel or consonant) and its analysis procedure (fixed filters or FFT). We present a procedure which varies as a function of the nature of the input signal. This method is based on FFT analysis using a variable with analysis window. Short windows are applied on the transient part of the signal, providing poor frequency resolution but good time resolution; they accurately permit to follow the speech signal in time during its fast temporal variations. Large windows are applied on the stationary parts of the signal, providing better frequency resolution, but poor time resolution. Transient parts of the speech order this window switching; they are detected using the statistical properties of the FFT; moreover the narrow windowing is coupled with an increase of the stimulation frequency. This strategy has been implemented using the Digisonic cochlear implant software, and clinically assessed on 6 regular cochlear implant users, owing to a consonant-vowel-consonant test. This Asynchronous-Interleaved-Stimulation (AIS) strategy provides the patients with better discrimination than fixed window FFT analysis. The coding protocol are described and results presented.

[Iatrogenic tinnitus and kophosis treated by cochlear implant. Apropos of a case]. / Bourdonnement sévère et cophose iatrogènes traités par implant cochléaire. A propos d'un cas.

A severe iatrogenic tinnitus has been successfully improved by cochlear implant, despite the hearing and intelligibility of the opposite ear were not profoundly impaired. This case report allows to discuss the eventual enlargement of the classic cochlear implant indications.

[Photochemotherapy in the treatment of carcinoma of the vocal cords of early stage (Tis, T1)]. / La photochimiothérapie dans le traitement des carcinomes du plan glottique à un stade limité (Tis, T1).

Photodynamic Therapy (PDT) is a treatment which can prove interesting in head and neck oncology for small squamous cell carcinomas. We studied 33 patients with vocal cord squamous cell carcinoma at an early stage who have been treated by Photodynamic Therapy from 1986 to 1992. We used a Dye Laser Aurora which produces light with a wavelength of 630 nm. The intervention was done under general anesthesia, 72 hours after the injection of hematoporphyrin derivative. The mean and the maximum follow-up was respectively 66 and 93 months. The local control after an exclusive PDT was 73% at 3 years, 5 years, 7 years. If this method fails, a conventional treatment may be used.

Clinical results for the DIGISONIC multichannel cochlear implant.

The DIGISONIC is a digitized 15-channel cochlear implant. A special version of this implant has been designed for use in the totally obstructed cochlea. This device has 10 separate electrodes that may be inserted, one by one, into 10 different holes drilled in the bony cochlea. The device's 128-point Fast Fourier Transform analysis supplies the patient with the entire set of the sound information between 100 and 7800 Hz. The stimulation rhythm is set at a programmable frequency among 125 and 400 Hz or slaved to the fundamental pitch frequency. The flexibility of the microprocessor makes it possible to select the best width and mean value of each frequency band for each electrode. Many speech-coding strategies may be easily programmed as a function of scientific desiderata. The authors present clinical results for the first 28 patients they treated with this cochlear implant.

Speech coding strategies of the digisonic fully digitized cochlear implant.

The Digisonic is a fully digitized cochlear implant. Because of its articulated array, its 15 electrodes can be inserted in the cochlea. Each electrode is recessed in a special silastic compartment of the array and has a very large stimulation area thanks to its large microrelief surface area. The small volume of its implanted receiver (flat cylinder diam 29 mm, 6.9 mm thick) allows it to be placed in 2-year-old children. The 128 point FFT of this device supply the patient with a full set of sound information between 64 and 7800 Hz. Electrode stimulation mode is sequential and stimulation rhythm is programmable. Electric crosstalk is decreased by the shape of the electrode array, and optionally by special programming of the neighboring electrodes. The speech therapist may select the width and peak value of each frequency band handled by each functional electrode. Because the versatility of this digitized emitter, many speech coding strategies can be easily programmed as a function of electrode responses or particular scientific considerations. A special version of this device, consisting of 10 separate electrodes, has been designed for use in patients with total obstruction of the cochlea. These insulated wires may be inserted one by one in the inner ear in 10 different recesses gently drilled in the bony cochlea. This device was placed in 46 patients between 1992 and 1994, including 8 young children (aged 2-9 years, mean 5 years) and 9 patients with total cochlear obstruction.

[Signal processing and clinical results with the French cochlear implant Digisonic]. / Traitement du signal et resultats cliniques de l'implant cochleaire francais Digisonic.

The Digisonic is a totally digitised multichannel cochlear implant remarkable for the versatility of its sound signal processing. Owing to its flexible and articulated array, its 15 electrodes are usually introduced in the scala tympani. A special version of this device has been designed to be used in case of total obstructed cochlea. It consists of separated electrodes which may be inserted one by one in the inner ear in different holes gently drilled in the bony cochlea. The possibilities of the microprocessor allow the speech therapist to carefully select the best width and mean value of each frequency band respectively devoted to each functional electrode. These parameters may be adapted to progressively improve the patient's hearing performances as a function of his phonemic discrimination and or the number and the tonotopy of his functional electrodes. Moreover, owing to the versatility of this digitised emitter a lot of speech coding strategies may be easily programmed as a function of eventual desiderata. Its high miniaturisation leads this implant to be particularly useful for young children. Results of our 38 first implanted patients (age 2-74; mean 42) including 7 cases of totally obstructed cochlea are reported.

[Cochlear implants and total cochlear obstruction]. / Implants cochléaires et cochlées totalement obstruées.

Total cochlea obstruction is not a contraindication for cochlear implant. We report our experience owing to the single channel cochlear implant Monosonic (9 cases), partial insertion of the electrodes-array (3 cases: 1 Digisonic and 2 minisystem) and, more recently the separate electrodes version of the Digisonic (6 cases). This new device is encouraging because it supplies 2/5 patients with telephone use.

[Results and indications of a multichannel cochlear implant in prelingual deep deafness]. / Résultats et indications de l'implant cochléaire multiélectrodes dans les surdités profondes prélinguales.

We report the clinical results of 23 prelingually deaf patients who recently benefited with multichannel cochlear implant. Owing to our experience we discuss the audiometric criteria and the patient's age which must be taken in count for the implanting decision.

[Evaluation protocol of cochlear implants in children under 5 years of age]. / Protocole d'évaluation de l'implant cochléaire chez l'enfant de moins de 5 ans.

Special tests are necessary to assess the cochlear implant efficacy on a prelingually deaf child implanted before age 5 y. We propose to quantify comportment, comprehension, auditory perception and expression as percentage of a same age normally hearing child's scores. The particular items are detailed.

[Improvement of clinical results by digitalization of a single channel cochlear implant]. / Amélioration des résultats cliniques par la numérisation de l'implant cochléaire monosonic.

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.

[Indications and results of cochlear implants in young children]. / Indications et résultats de l'implant cochléaire chez le jeune enfant.

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.

[The choice between mono- and multielectrode implants in rehabilitation of total deafness in young children]. / Le choix entre les implants mono et multi-électrodes dans la réhabilitation des surdités totales du jeune enfant.

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.

["Monosonic" one canal digital implant]. / L'implant cochléaire monocanal numérique "Monosonic".

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.