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Biomedical subjects

M Ouayoun

Publications and source records attributed to M Ouayoun.

At least 19 recordsLinked to original sources
PubMed2000

[Q.A.L.Y. index and assessment of cost efficiency of the cochlear implant in acquired profound deafness].

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.

Adult↗
PubMed1999

A study of speech fractal dimensions.

The fractal dimension (D) of a signal gives an estimate of its degree of freedom, which allows estimation of its fluctuations. Using 16 kHz time sampling and the box counting method we studied the Ds of some of the main stationary parts of French speech, the phonemes [a], [e], [i], [o], [y], pronounced 4 times by 10 males and 10 females. Our study demonstrated that the stationary signal of vowels is not fractal, but may, at the smallest scale, provide a kind of signature for each vowel, though the present categorization is not totally significant. Since the box counting method objectifies and quantifies the roughness of the signal, this procedure may be useful for clinical applications. In case of dysphonia, moreover, these signatures could be perhaps be included in the speech signal processing of cochlear implants.

Female↗
PubMed1998

Slow-growing labyrinthine masses: contribution of MRI to diagnosis, follow-up and treatment.

We report the use of MRI in the diagnosis, follow-up and therapeutic management of three cases of intralabyrinthine Schwannoma. The diagnosis was based on the history and initial and follow-up MRI findings. The main feature suggesting the diagnosis was a nodular intralabyrinthine mass of low signal intensity on T2-weighted images, and high or isointense signal on T1-weighted images (relative to cerebrospinal fluid), which showed contrast enhancement. Follow-up imaging showed growth of the tumour in one patient. One patient underwent surgery for severe tinnitus. To detect these lesions, MRI should be focussed on the inner ear, using thin-section T2-weighted and T1-weighted images before and after contrast medium. MRI allowed informed surgical planning.

Adult↗
PubMed1998

[Digital multi-filter auditory prosthesis: study of its efficiency in function of number of filters and their programming].

We designed a prototype of a 7-filter digital auditory prosthesis table prototype. For each of these filters frequency band width, amplification and compression were programmable in order to adapt these parameters to the deaf patient's audiometric particularities. We compared the hearing improvement it was possible to obtain either with the 3-analogue-filter auditory prosthesis Triton 3004 from Siemens, or with our prototype as a function of the number of filters (3, 4 or 7) and their frequency band width programmability. We tested 21 patients suffering from middle or severe neurosensory hearing loss. This study allows to demonstrate that to overpass the present analogue T004 device a 7 programmable-width-filter strategy seems to be the most appropriate. Further studies benefiting with material improvement of our prototype and finer audiometric adjustment of filter strategies as well as long term clinical studies have to be carried out.

Acoustic Stimulation↗
PubMed1998

[Cochlear implant and cerebral dominance].

On right handed people the right ear is considered to transmit speech information, and the left ear musical and cognitive information. These dominating ear properties are not exactly symmetrical in the left handed population, and are more consistent in females than in males. CI efficacy assessment is strongly based on speech intelligibility performances, because these criteria allow to measure the social reinsertion and communication possibilities. Consequently, one may ask if the relationship of the implanted side and the patient's handness could not be an important factor of this CI efficacy. We studied this relationship on 71 post-lingually deaf adult implantees. We measured patients handness using the Schachter's version of the so called Edimburg questionnaire described by Geschwind; this measurement has been moderated to take count of ambidextrous and mixed-handed population. Post operative performances has been assessed using the Francophone Protocol devoted to adults. We found that there is no significant correlation between these post-operative performances and the studied relationship. We estimate: 1) This absence of correlation is probably due to the high number of data which lead to determine the ear for implanting. 2) As far as this choice is feasible, dominating ear must nevertheless be elected, not only for theoretical reasons, but because the dominating hand may be easily employed for antenna adjustment. 3) As handness is strongly evident only after 4 y.o., and as left-handness seems to be more frequent on a congenitally deaf population, this choice is more problematic on less than 2 y.o. deaf children.

Cochlear Implantation↗
PubMed1998

[Cochlear implant in the aged patient].

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.

Adult↗
PubMed1998

[Indications for the cochlear implant in partial deafness of the adult].

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.

Audiometry, Pure-Tone↗
PubMed1997

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.

Cochlear Implants↗
PubMed1997

[Nuclear magnetic resonance and cochlear implant].

Chou underlined that ive potential effects may be anticipated if MRI is realized on implantees: 1) force on the implant by strong magnetic field, 2) current induced by the implant in the radiofrequency (RF) field, 3) damage of implant by RF exposure, 4) MRI image distortion caused by the implant, 5) implant and adjacent tissue heating due to the absorption of RF energy. We studied the reality of the four first of these risks on the Digisonic cochlear implant from MXM using the Siemens Magneton 42 SP, which supplied the implants during 10 minutes with 1 Tesla magnetic field, RF 42 MHz, maximum intensity 10 kV. During T1 and T2 sequences we could notice that: 1) Provided the receiver is strongly attached in its skull niche as requested by normal surgical procedure, no deplacement may be observed: 2) No adverse current may been observed as well on the implanted electrodes as in the internal circuitry; 3) No damage or adverse magnetisation have been detected in the 3 studied receivers; 4) Cerebral imaging of the animal is moderately darkened by the implant. The volume of the shadow involved by the implant is approximately three times the volume of the implant. As Chou demonstrated that no observable heating could be detected after a long MRI sequence, and as Portnoy using Nucleus device observed also that neither adverse current nor implant damage could be detected, we estimate that there are no real contraindication to perform MRI on implantees, provided the surgical attachment has been correctly realised. Practical attitudes will be evoked and discussed.

Animals↗
PubMed1997

[Imaging of ORL diseases in acquired immunodeficiency syndrome].

More than 50% of patients with acquired immunodeficiency syndrome (AIDS) present a lesion affecting parotid gland, lymph nodes, paranasal sinuses, pharyngo-larynx or temporal bone. In about 20% out of cases affected patients present different head and neck lesions at the time of evaluation. Most often, clinical examination and endoscopy are sufficient to perform diagnosis and to manage the disease. Imaging studies (CT or MRI) are indicated when the nature of the disease is unknown or when a map of the process is mandatory for therapeutic approach. Some imaging features are strongly suggestive of HIV infection: parotid cysts associated with hyperplasia of the nasopharynx and cervical lymph nodes enlargement; labyrinthitis and multinevritis; and head and neck squamous cell carcinomas in non alcoolo-tobacco addicted patients. Such diseases suggest the need for knowledge of the patient's seropositivity status.

Acquired Immunodeficiency Syndrome↗
PubMed1997

[Persistent facial paralysis: contribution of imaging to identification of perineural infiltrating tumor].

To describe imaging features suggestive of retrograde perineural spread in progressive facial palsy without known tumoral origin. Two reports of perineural infiltration by salivary malignant tumors were diagnosed on abnormal enhancement of the facial nerve associated with an abnormal nerve enlargement (1/2). These unsuspected tumors were located in parotid gland (1/2) and the sub-maxillary gland (1/2). ENT tumors (especially adenoid cystic carcinomas) should be carefully searched in case of perineural spread, as these tumors may be misdiagnosed due to their size, location and signal. Therefore, imaging studies of facial palsy should include temporal bone, skull base, parotid gland, submaxillary gland and sub cutaneous areas of the face. A sub-maxillary gland tumor should be searched in case of facial palsy associated with glossodynia.

Carcinoma, Adenoid Cystic↗
PubMed1997

[Asynchronous sequential stimulation. A new signal treatment for cochlear implants].

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.

Acoustic Stimulation↗
PubMed1995

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.

Child↗
PubMed1995

[Signal processing and clinical results with the French cochlear implant 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.

Adolescent↗
PubMed1995

[Ambulatory laser and turbinectomy in the treatment of nasal obstruction. Apropos of 68 cases].

The purpose of this prospective study was to compare subjectively and objectively the efficiency of laser vaporisation against surgical procedure in treatment of nasal obstruction related to vasomotor rhinitis. 40 inferior nasal turbinates laser vaporisations were compared to 28 surgical inferior turbinectomies. This trial was based on rhinomanometric data before and after laser or surgical management and on appreciation of individual nasal comfort. The results obtained with conventional surgery were slightly better than laser vaporisation; however this new procedure succeed in 75% of cases with a mean of one year follow-up. The rhinomanometric++ findings appeared especially contributing when significant disorders exist before treatment.

Adolescent↗
PubMed1992

[Carhart's effect; a study of postoperative outcome of 47 surgically treated cases of otosclerosis].

The Carhart Effect can explain a bone conduction improvement after stape surgery in otosclerosis, because of the mechanical factors in transmission of sound vibrations. The authors have studied 47 cases of total stapedectomy for otosclerosis to point out this bone conduction improvement. A correlation between the bone conduction improvement and others parameters has been searched: a statistic correlation between pre-operative bone curve and the 1000 Hz bone conduction improvement has been found.

Audiometry↗
PubMed1990

[Patients excluded from voice restoration after total laryngectomy].

Concerning 73 radical laryngectomy operations carried out at the Hôpital Tenon in the period between july 1985 and july 1989, the authors studied the mode of vocal restoration used and the patient population not benefitting from any of the procedures used. Esophageal voice was utilized initially in 19 patients; a tracheo-esophageal fistula (surgical shunt or puncture with Blom-Singer prosthesis) was created during laryngectomy in 19 patients, and secondary tracheo-esophageal puncture was performed in 13 others. Twenty patients had no vocal restoration operation performed. In a large number of the patients, the tracheo-esophageal fistulas restored a normal voice. In the end, 38% of the laryngectomized patients did not have their voice restored. The various causes for such a high percentage of exclusions that are discernable are discussed. Lack for motivation on the part of the patients is a major reason, irrespective of the technique used.

Adult↗