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Biomedical subjects

A Morgon

Publications and source records attributed to A Morgon.

At least 91 records · Page 5Linked to original sources
PubMed1991

[2 cases of neurinoma of the mastoidal portion of the facial nerve: diagnostic contribution of MRI].

The authors report 2 cases of patients presenting a neurinoma of the 3rd portion of the facial nerve. In the 2 cases, the surgical observations correlated perfectly with the results of the radiological examinations (scanner and MRI). The clinical and paraclinical presentation of this rare tumor is recalled, emphasizing the additional contribution of imaging techniques: the scanner is indeed indispensable for evaluating the osseous destructions on the intrapetrous trajectory of the facial nerve, whereas MRI (in particular with injections of gadolinium) evaluates the exact tumoral limits as best as possible.

Adult↗
PubMed1990

Variability of the influence of a visual task on the active micromechanical properties of the cochlea.

The effect of a visual task on the active micromechanical properties of the cochlea studied by the evoked otoacoustic emissions (EOAEs) has been the subject of only one published study (Brain Research, 44 (1988) 380-383). In order to examine the reliability of this effect, a similar study has been run on 16 subjects. A significant decrease in EOAEs during a visual task was obtained for 3 subjects. The two subjects whose decrease was the most significant were tested again one month later and the same effect was found. This striking interindividual variability is discussed in terms of olivo-cochlear neuronal excitability.

Acoustic Stimulation↗
PubMed1990

Effect of contralateral auditory stimuli on active cochlear micro-mechanical properties in human subjects.

The present study investigates the possibility that contralateral auditory stimulation along medial efferent system pathways may alter active cochlear micromechanics and hence affect evoked oto-acoustic emissions in humans. A first experiment, involving 21 healthy subjects showed reduction of oto-acoustic emission amplitude under low intensity contralateral white noise (from 30 dB SPL, 10 dB SL, upwards). The effect is found for intensities below the acoustic reflex threshold (85.2 dB HL). A second experiment, involving 10 of the above 21 subjects, sought to rule out any technical artefact. Recording was again carried out, but after sealing of the contralateral ear with a silicon putty plug. No contralateral intensity effect on oto-acoustic emission amplitude was found for contralateral intensities below 65 dB SPL. In subjective perception terms (dB SL) an effect was found under sealing when the sound reached or passed above the 10 dB SL level. These two findings confirm the preceding experiment. The third experiment investigated the role of transcranial transmission of the contralateral auditory stimulus. 16 subjects having total unilateral deafness and one healthy ear were tested by the same procedure as above. No fall-off in oto-acoustic emission amplitude was found for contralateral stimuli equal to or less than 80 dB SPL. There is thus a contralateral auditory stimulus effect on active cochlear micromechanics. The most appropriate explanation involves the medial cochlear efferent system, excited at brainstem level via the afferent auditory pathways. Alteration of active cochlear micromechanics seems promising at a basic level, pointing, as it does, to an interactive cochlear functioning which can be investigated by simple, non-intrusive, objective techniques which can be used with human subjects. We have here a model for functional exploration of the medial olivocochlear efferent system.

Acoustic Stimulation↗
PubMed1990

Age-related changes in evoked otoacoustic emissions.

Outer hair cells of the organ of Corti play an important part in the genesis of evoked otoacoustic emissions (EOAEs), which are related to cochlear biomechanics. The aim of this study was to investigate the age factor in relation to EOAEs in 166 ears of subjects between 6 weeks and 83 years of age. The results show that when age increases, the presence of EOAEs by age group and the frequency peak in spectral analysis decrease, and EOAE threshold increases. Thus, there is an effect of age upon EOAEs, and it seems linked with alteration of cochlear biomechanics and/or hair cell loss. Such an effect has to be taken into consideration when EOAEs are used in clinical applications, and limits the use of EOAEs in older subjects.

Adolescent↗
PubMed1990

Minnesota Multiphasic Personality Inventory in tinnitus disorders.

The relation between Minnesota Multiphasic Personality Inventory (MMPI) and tinnitus was examined in 100 subjects with tinnitus disorders. The overall profile of tinnitus sufferers on the MMPI was normal. Higher scores on the depression scale were obtained in males. High hypochondria scores were related to long duration of tinnitus. High psychoasthenia scores were associated with hearing loss. Despite an analogy previously described between chronic pain and tinnitus, the psychometric parameters of tinnitus and of headaches are quite different.

Adult↗
PubMed1990

[Effect of attention on audition. Contribution of the study of the olivocochlear efferent system].

It is possible by studying the Evoked Otoacoustic Emissions (EOAEs) to detect an effect of selective attention on the cochlea. The authors present the main data of the literature and the results of their works. They show an effect of visual attention as well as auditory attention on the EOAEs. This effect is not the same whether attention is visual or auditory. There is a result of selective attention as early as the cochlear level.

Attention↗
PubMed1990

[Experimental study in dogs of a human reticulated placental IV collagen film for myringoplasty].

This experimental study involving dogs tested type IV human collagen as a biomaterial for use in the tympanic membrane reconstruction. A loss of substance was induced for the two tympanic membranes, and a type IV collagen graft made to one side. The kinetics of receiver fibroblast colonisation of the graft, as well as in the case of resorption, were studied. Anatomopathological examination revealed the process of reconstitution. This animal study prepares the way for studies on man.

Animals↗
PubMed1990

[Reconstruction of the external ear in children. Contribution of the clay model cartilage sculpture].

The use of rib cartilage graft in ear reconstruction gives good cosmetic results after the age of 8. However three main conditions must be taken into account: 1) a perfect framework sculpture; 2) good quality of the skin in order to provide a soft tissue free of scars and able to drape the framework in all the details of the sculpture; 3) a soft but useful succion system allowing a good coaptation between the framework and the skin without vascular damage. Most of the surgical failures are due to skin scars which compromise the elasticity of the cutaneous pocket. The authors recommend to wait until the age of 8 before any surgery in order to keep the skin intact and to let the ribs grow. The problem of hearing can be treated as secondary.

Cartilage↗
PubMed1990

[Trimetazidine and degenerative deafness. Effect on hearing and integration].

This study was conducted in order to assess the activity of trimetazidine dosed at 60 mg/day in patients presenting degenerative loss of hearing. Ten centers participated in this multicenter double-blind placebo-controlled trial which spanned 6 months. Included were 251 patients (118 women, 133 men) presenting with pure perception bilateral symmetrical deafness concerning predominantly the acute frequency range. 228 patients terminated the study, including 115 in the trimetazidine group and 113 in the placebo group. The evolution over a 6-month treatment period was significantly better with trimetazidine as regards the following parameters: audibility as assessed by pure-tone audiometry, namely at the acute frequency range (p = 0.002), intelligibility as assessed by speech audiometry (p = 0.008), subjective evaluation of hearing loss and its impact on the patient's social life. Results confirm the value of trimetazidine hearing loss management, based on clinical, subjective criteria as well as audiometric ones. Parameters reflecting best trimetazidine's efficacy were intelligibility and the psychological/behavioral impact of the impairment, allowing for better social integration of the subject.

Aged↗
PubMed1990

[Use of human placental type IV collagen in tympanoplasty. Results of initial animal experimentation].

This study presents the use of human type IV collagen film in myringoplasty in dogs. Evaluation criteria were clinical (repeated otoscopies) and histological (histological analysis of cicatrised membranes). This new biomaterial should seem to be a technological advance on temporal bone aponevrosis or perichondria auto-grafts. This study constitutes the necessary preliminary research to any application in man.

Animals↗
PubMed1989

Evoked otoacoustic emissions and sensorineural hearing loss.

Following Kemp's original studies, several others have confirmed the existence of otoacoustic emissions. Their clinical relevance remains, however, to be clarified. The various published studies have concerned small series. This study sought to specify otoacoustic emission characteristics in relation to sensorineural hearing loss (148 ears of 76 subjects). The results show that the presence of otoacoustic emissions drops as a function of hearing loss and that there is a highly statistically significant correlation between otoacoustic emission threshold and hearing loss at the 1000-Hz frequency. Otoacoustic emissions are never found when hearing loss at 1000 Hz exceeds 40 dB hearing level and when the mean audiometric hearing loss (at 500, 1000, 2000, and 4000 Hz) exceeds 45 dB hearing level. The main practical conclusion is that otoacoustic emission presence indicates middle frequency functional integrity of the outer hair cells of Corti's organ. Absence of otoacoustic emissions is harder to interpret.

Adolescent↗
PubMed1989

Are click-evoked BAEPs useful in case of neonate hyperbilirubinemia?

There is still controversy about the usefulness of click-evoked brainstem auditory evoked potentials (BAEPs) for the investigation of neonatal hyperbilirubinemia. The present work concerns the study of click-evoked BAEP responses in a population of 72 hyperbilirubinemic children (conceptional age between 33 and 42 weeks). Their bilirubinemia rates were between 219 and 600 mumol/l. The waves I, III and V were always present, and click BAEP thresholds were normal in all subjects. Latency anomalies were found only for 8 of the 72 subjects. The comparison of subjects having the higher (greater than 307 mumol/l) bilirubin levels with the group having the lower ones failed to show any significant differences for the I-III and I-V intervals. The influence of prematurity in BAEP alteration has not been demonstrated in this study. These data show, on the one hand, normal click-BAEP thresholds but, on the other hand, alterations of central conduction time in some hyperbilirubinemic newborns. It seems that other factors than hyperbilirubinemia might be operating.

Acoustic Stimulation↗
PubMed1989

Is there a difference between extrauterine and intrauterine maturation on BAEP?

A difference between extrauterine and intrauterine maturation on BAEP has not been established, remaining a subject of controversy. The present study involved 76 children, aged between 36 and 37 weeks (conceptional age), with an extrauterine life duration of equal to or less than 2 weeks (N = 46) or more than 2 weeks (N = 30). The latencies for waves III and V, and the I-III and I-V intervals were significantly shorter for the neonates with a greater extrauterine life duration. An explanation for this finding is discussed: the head size is significantly smaller in the group with a greater extrauterine life duration. An influence of extrauterine life duration on BAEP is thus shown, but it seems to reflect the anatomical consideration and not to peripheral auditory system maturation.

Aging↗
PubMed1989

Validity of bone conduction stimulated ABR, MLR and otoacoustic emissions.

The present study considers the validity of objective auditory investigation via bone conduction. Auditory Brainstem Responses (ABR) and Middle Latency Responses (MLR) were recorded in response to a bone vibrator stimulation with or without continuous bilateral air white noise masking. In all cases, such masking was found to result in an absence of recorded evoked potentials. It shows that under bone-conducted stimulation the evoked potential recorded is purely auditory, with no additional mechanical somatosensory component. In a further study, the feasibility of oto-acoustic emissions (OAEs) via bone conduction is demonstrated. These OAEs are, for a given subject, comparable to those found for air-transmission stimulation.

Adolescent↗
PubMed1989

[Effect of age on otoacoustic emissions].

The aim of this work was to study the age-effect on otoacoustic emissions (OAE) (93 subjects, 166 ears). The results show that when age increases the presence of OAE by age group decreases as well as the frequency peak in spectral analysis. The OAE threshold increases with age. So there is an effect of age upon OAE. The effect seems linked with alteration hair cell loss and/or alteration of cochlear biomechanics.

Acoustics↗
PubMed1988

Effect of brainstem auditory evoked potential stimulus intensity variations in neonates of small for gestational age.

The latencies of brainstem auditory evoked potentials were compared first in 25 small for gestational age (SGA) neonates (conceptional age less than 43 weeks) matched with 25 appropriate for gestational age (AGA) neonates, and then in the 8 younger SGA neonates (less than 37 weeks) matched with 8 AGA neonates. In this last subgroup the results showed that the I-V interval is shorter in SGA than in AGA neonates, as previously described. This shortening effect is essentially linked to a lengthening of wave I. So the results are discussed in terms of immaturity of the basal end of the cochlea, rather than of precocious development of the auditory brainstem neural function in SGA infants.

Brain Stem↗
PubMed1988

Effect of stimulus intensity variation on brainstem auditory evoked potentials. Maturational changes.

The effect of stimulus intensity variation on brainstem auditory evoked potentials in premature and full-term neonates has been studied in two experiments. They show that the effects are different according to age and to waves. The variation of latencies is greater the younger the child and it is clearer with wave I than waves III and V. The findings are discussed in terms of the maturation of the basal part of the cochlea.

Acoustic Stimulation↗