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Biomedical subjects

A Morgon

Publications and source records attributed to A Morgon.

At least 19 recordsLinked to original sources
PubMed1992

Differential effects of ear-canal pressure and contralateral acoustic stimulation on evoked otoacoustic emissions in humans.

The effect of ear canal pressure variation (ECPV) on click evoked otoacoustic emissions (EOAEs) was compared to the suppressive effect observed with contralateral acoustic stimulation (CAS) in 11 healthy subjects. Both total EOAE amplitude and amplitude of 200 Hz frequency bands (22) were analyzed. Our results revealed that the ECPV as the CAS induced a decrease of the total EOAE amplitude; these two factors showed an additive effect when they are conjoint. The study of the EOAE frequency bands showed that the majority of them decreased under CAS and ECPV; however, a few bands are not affected. Moreover, it appeared that amplitude of the EOAE frequency bands were not modified in a similar way between the two factors: indeed some bands around 4.1 kHz did not decrease either by CAS or ECPV. These results suggest that these applied factors exert different actions on EOAEs. Moreover, the lack of a decrease effect for the same bands, both with CAS and ECPV, may explain the vulnerability of some cochlear locations.

Acoustic Stimulation↗
PubMed1992

Influence of spontaneous otoacoustic emissions (SOAE) on acoustic distortion product input/output functions: does the medial efferent system act differently in the vicinity of an SOAE?

Otoacoustic emission (OAE) generation mechanisms reside in the active micromechanical properties of the organ of Corti, and especially in the outer hair cells (OHCs). OHCs are strongly innervated by medial efferent olivo-cochlear fibres. Decrease of the intensity of transiently evoked otoacoustic emissions (TOAEs) and modification of spontaneous otoacoustic emissions (SOAEs) during acoustic stimulation of the contralateral ear have already been shown in humans. Similar results were obtained in guinea pigs with a decrease of 2F1-F2 acoustic distortion products (DPOAEs) and a suppression of the effect with sectioning of the floor of the fourth ventricle. The present study sought to investigate the influence of contralateral auditory stimulation on DPOAEs recorded in humans. It shows a decrease in DPOAE intensity for all frequencies, at levels above 45 dB SPL of contralateral broad band noise. This effect was found at levels of contralateral BBN well below the acoustic reflex threshold, and in subjects without acoustic reflex. Moreover, the influence of transcranial transmission could be ruled out since no effect was found when contralateral BBN applied to the altered ear of totally unilaterally deaf patients. Thus, the contralateral acoustic stimulation effect on DPOAEs provides a new means of functional exploration of the medial efferent system in humans. The effect obtained is more ample at low primary frequency levels. Moreover, as DPOAEs are known to be stronger and to show more irregular input/output function patterns in the vicinity of an SOAE, the influence of contralateral auditory stimulation was studied for DPOAEs recorded at 10 Hz, 50 Hz and 150 Hz from an SOAE frequency.

Acoustic Stimulation↗
PubMed1992

Model for understanding the influence of some parameters in cochlear implantation.

Considering the recognition performance obtained by an implanted patient, the authors have developed models to explain the decrease in performance when the number of open channels on the prosthesis is increased. The French cochlear implant Chorimac was used in this experiment. Two models have been developed. The first is monodimensional and the second is multidimensional. They respectively represent an increase in information and its superposition. Results suggest that for the patient, the superposition factor prevails and is detrimental to recognition. Its elimination should be a major goal. A good selection of electrodes in a relatively small number seems to be the best policy. This is already done in some cochlear implants. Some other parameters in the signal that seem worth being analyzed are introduced.

Cochlear Implants↗
PubMed1992

Effects of contralateral white noise on click-evoked emissions in normal and sensorineural ears: towards an exploration of the medial olivocochlear system.

The association between contralateral stimulation and evoked otoacoustic emissions (EOAEs) allows study of sound-evoked olivocochlear feedback and then of the medial olivocochlear system. A method allowing quantification of sound-evoked olivocochlear feedback is proposed. The feedback is present in almost all normal-hearing subjects, but with great interindividual variability. In sensorineural hearing loss, the feedback is present in 20 out of 21 subjects. One paradoxical clinical case is described with a unilateral increase of EOAE intensity during contralateral stimulation.

Acoustic Stimulation↗
PubMed1992

Evoked otoacoustic emissions: relative importance of age, sex and sensorineural hearing-loss using a mathematical model of the audiogram.

The influence of age, sex and of hearing loss on the EOAEs were studied in 140 subjects. The EOAEs were never found when hearing loss on the best hearing frequency was above 40 dB HL and when the threshold of intelligibility was above 45 dB HL. The presence of EOAEs therefore does not only give specific information on the midfrequencies, but also shows a hearing loss below or equal to 40 dB HL on at least one frequency. In addition, there is a relation between the audiometric curve and the spectrum analysis of EOAEs. These seem to be promising results for clinical applications.

Acoustic Stimulation↗
PubMed1992

[Tracheotomy in children. Indications, major surgical principles, importance of nursing].

Tracheotomy in children has two main fields of indication: 1) obstructions of the upper respiratory tract, the main cause being today the post-intubation stenosis; 2) long term mechanical ventilation. When performed in good conditions, with adapted care, there are few complications, among them the accidental denaculation being the most worrying. When long-term tracheotomy is needed, parent-education, together with special equipment and adapted environment may allow the return of the tracheotomised child at home in secure conditions. Special attention with preventive measures during intubation is recommended in order to reduce the number of tracheotomies for post-intubation stenosis.

Child↗
PubMed1992

[Chronic hoarseness in children. Evaluation based on personal series of 64 cases].

Chronic hoarseness is frequent among children, as shown by 64 cases observed over an 18-month period in a specialized phoniatric outpatients clinic. Age at the first consultation for these 64 patients was 3-14 year although the hoarseness was already known for more than 1 year in 40 patients (62.5%). The main findings at laryngoscopy were an edematous vocal cord (33%), a unilateral or bilateral nodular lesion (26%), and an epidermoïd cyst (17%). The larynx was normal in 2 patients only. Orthophonic re-education was prescribed for 45 patients (70%); it was followed by laryngeal microsurgery in 3 patients: 9 patients were completely cured, 26 were improved, 4 showed no improvement, 16 could not be located for follow-up. Chronic hoarseness in children has numerous etiologies which can be divided into 5 main groups. The 2 more frequent are the hyperkinetic or hypokinetic laryngeal dysfunctions and the congenital lesions. The 3 other groups are much less frequent: juvenile laryngeal papillomatosis, recurrent palsy and pithiatic aphonia. Laryngoscopy is important for the diagnosis. Orthophonic re-education represents the main treatment; it completes the surgical treatment when microsurgery of the larynx is necessary.

Adolescent↗
PubMed1992

[Acquired peripheral facial palsy in children. Current data illustrated by 66 recent personal cases].

The authors observed 66 cases of peripheral facial palsy (PFP) in children during a 5-year period (1986-1990). Bell's palsy (idiopathic facial paralysis) occurred in 26 children (39.3%), 1 month to 14.5 years old, with a complete recovery in 95% of the cases; a surgical decompression was carried out in 2 cases. The PFP was related to otitis in 16 cases (24.2%): acute otitis media (6), mastitis (4), serous otitis (5), cholesteatoma (1); the treatment was medical and surgical in all cases with complete recovery in 15 cases. In 15 cases the PFP was secondary to trauma (13) or surgery (2); complete spontaneous recovery occurred in 11 cases, and partial recovery following surgical treatment in 2 cases. A viral origin was retained in 6 cases: herpes zoster (3), mumps (1), echovirus (1), herpes (1); the recovery was complete in 4 cases, partial in 2 cases. In 3 cases the PFP was related to a rare cause: lymphoma, metabolic acidosis, Melkerson-Rosenthal syndrome. Bell's palsy remains the main cause of PFP in childhood; other etiologies can be ruled out by the case history, a careful physical examination, and a limited number of laboratory and/or X-ray studies; medical treatment, in particular prednisone, does not seem to have an effect upon the rate of recovery which is spontaneously high; similarly there is no evidence that surgical decompression really modifies the rate of recovery so that the authors suggest that it should be reserved to the complete forms with no clinical and electrical evidence of recovery after 3 weeks.

Adolescent↗
PubMed1992

[Congenital cysts and fistulae of the face and the neck].

The authors review the embryological, clinical and therapeutic aspects of congenital facial and cervical cysts (C) and fistulae (F), based on a personal series of 85 cases (facial: 18, latero-cervical: 29, mediocervical: 38) observed during a 5-year period. The facial forms are the result of an incomplete coalescence of the facial buds and most often present as helical F (17/18). Laterocervical C and F are due to abnormal evolution of branchial clefts; the main clinical forms are related to anomalies of the 2nd branchial cleft (24/29), usually presenting as sinus localized at the anterior border of the lower third of the sternocleidomastoid muscle (8) and amygdaloid cysts. Thyroglossal duct cysts are the most frequent of the medio-cervical C and F (35/38); they usually present as a mediocervical cyst in the thyro-hyoid space which may be revealed by an infection or a fistulization. The only appropriate treatment of congenital facial and cervical C and F is surgery providing that the resection is meticulous with complete resection of the fistula in order to avoid relapse. Complete resection also suppresses the risk of secondary malignant degeneration of amygdaloid and thyroglossal duct cysts.

Adolescent↗
PubMed1992

[Reduction laryngoplasty by external approach for glottic incompetence. Current role, demonstration of its efficacy by objective analysis of parameters of vocal quality].

Authors talk about the place of surgical treatments with cervicotomy in abducted vocal cord, about the statistics of the department of Phoniatrics of the Hospital Edouard Herriot in Lyon. These techniques have actually a marginal place. But the analysis of a recent case shows us that endoscopic treatment for vocal fold augmentation with biomaterials such as collagen or teflon can fail. So ENT surgeons have to absolutely know the Guerrier's technique to improve the quality of the voice when injectable biomaterials fail. With the description of this case, we will describe the objective analysis methods of the voice parameters that we use in the department.

Adult↗
PubMed1992

[Vertigo in children].

The main difference between childhood and adulthood vertigo is that the evaluation of symptoms and examination pose special challenges in pediatric patients, depending on age. Vertigo in pre-teenage children is similar to vertigo in adults. In contrast, although benign paroxysmal vertigo, vestibular neuronitis, and Ménière's vertigo occur in children, the distribution of these conditions is different from that seen in adults. After vestibular and cochlear investigations as well as a CT scan or MRI study to outrule a tumor of the posterior cerebral fossa, the diagnosis of vestibular vertigo is established. Often, the diagnosis proposed cannot be considered as final and requires reappraisal according to the long-term course. Collation of case-reports with highly accurate documents is essential in order to strive to develop more satisfactory approaches.

Child↗
PubMed1991

Noise and medial olivocochlear system in humans.

Evoked otoacoustic emissions (EOAE) and sound evoked olivocochlear feedback were performed in 200 subjects (noise induced hearing loss (NIHL), n = 109; sensori-neural hearing loss (SNHL), n = 91). Intensity of EOAE is greater in NIHL than in SNHL. This result does not seem to be related to the medial olivocochlear system since sound olivocochlear feedback was not significantly different between the two groups. No correlations were seen between temporary threshold shifts (TTS) and sound-olivocochlear feedback in the NIHL group.

Acoustic Stimulation↗
PubMed1991

Spontaneous otoacoustic emissions and sensori-neural hearing loss.

This study sought to clarify the clinical relevance of spontaneous otoacoustic emissions (SOAEs) and to define the hearing loss level (and frequency) at which absence of SOAE is found. Findings from 126 ears of patients with sensori-neural hearing loss showed an incidence of SOAEs in 18.25% of the cases (23 out of 126 ears). SOAEs were never found when hearing loss at 1,000 Hz exceeded 10 dB. The presence of SOAE seems to indicate a good cochlear functioning at least in the mid-frequencies. Although the incidence of SOAEs is markedly lower than that of evoked otoacoustic emissions (EOAEs), SOAE recording is shown to be a good test, rapid, non-invasive for audiological screening, the presence of SOAE confirming a hearing threshold of less than 10 dB at 1,000 Hz, the absence of SOAE being inconclusive.

Acoustic Impedance Tests↗
PubMed1991

Evoked otoacoustic emissions: correlates between spectrum analysis and audiogram.

Correlations between spectrum analysis of evoked otoacoustic emissions (EOAEs) and hearing losses have been calculated in 150 patients with pure sensorineural hearing loss. Significant correlations were found. The greater the high-frequency spectral components of the EOAE, the better the high-frequency hearing. However the relationship is complex, and it does not seem possible to establish an audiogram knowing only the spectrum analysis of EOAEs.

Adult↗
PubMed1991

[Dural fistula of the lateral sinus. Apropos of 2 recent cases].

On the basis of two recent cases of dural fistula of the lateral sinus, the authors review the literature relating to this type of arteriovenous fistulae. The development of selective arteriographic techniques has allowed better knowing them, ensurgin the diagnosis and also treating them with embolization techniques. The role of the ENT specialist is no less important: during the clinical stage, it for him to recognize the pulsatile character of a tinnitus and to demonstrate it in order to establish the diagnosis.

Aged↗
PubMed1991

[Value of collagen type IV in tympanoplasties. Animal experimentation in rats].

The authors recall the importance of collagen in the ultrastructure of the lamina propria and the properties of the type IV collagen concerning epidermic healing. Tympanomeatic graft composed of reticulated type IV collagen was used as a graft in rats. This experimental study demonstrated a good stability of the graft 40 days after operating. A new non toxic cross linking technique has been developed to stabilise of the biomaterial. The type IV collagen film shows good properties for the growth and the differentiation of epithelial cell like keratinocytes.

Animals↗