Biomedical subjects
R Dauman
Publications and source records attributed to R Dauman.
[Fluctuating deafness].
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[Tinnitus and deafness].
The relationships between tinnitus and hearing loss are studied from a clinical prospect. Five critical points are discussed. 1. Some degree of hearing loss is found in the vast majority of tinnitus patients; but an individual may well have a sensorineural hearing loss and no tinnitus at all. 2. A minor adjunction to the neurophysiological model of Jastreboff is proposed to take account of the association between tinnitus and hearing loss. 3. Tinnitus appears to cause more distress when hearing loss is marked. 4. Self-reported hearing loss should be considered when implementing habituation sound therapy. 5. According to McKinney, the rate of success on tinnitus that can be expected with habituation sound therapy is not significantly affected by hearing level.
Long-term outcome of childhood hearing deficiency.
This report is based on the questionnaire responses of 95 young hearing-impaired adults (39 with moderate, 20 with severe and 36 with profound hearing loss) who were investigated in the department of paediatric audiology during childhood. Half of the individuals were educated in ordinary school (integration) and half in an institution for hearing-impaired children. Responses on social and professional insertion were compared with audiometric threshold and educational setting. Results indicate that both hearing level and educational environment influence current mode of communication and use of hearing aids. Familial factors also seem to have an influence. Oral communication is a poor predictor of employment, whereas professional qualifications enhance the chances of finding a job. Obtaining a non-professional degree appears to be unsuited for improving the employment rate of the hearing-impaired child.
[Multi-frequency tympanometry in experimentally-induced cochlear lesions in chinchillas and guinea pigs].
OBJECTIVES: To establish that susceptance-conductance tympanograms at a probe-tone frequency of 2 kHz reflects the status of the annular ligament (AL) and through it of the cochlea. METHODS: Experimental study in 5 chinchillas and 22 guinea pigs. Six validating experiments were used: blockages of the stapes and of the round window membrane (RWM), fistula of the RWM, fluid removal from the cochlea, injection of saline in the scala tympani (ST) and acoustic trauma (AT). Quantitative data (mean values of Y226, FR, Y2000, G2000 and B2000) and shape of the curves were analyzed before and immediately after lesions were done. RESULTS: Guinea pig was the most convenient provided bulla was vented and the same tip was used along the experiments. Only the shape of the curves are discriminant: 1/a supplementary sharp peak, centered around negative pressures, is observed in Y/G tympanograms in every case of RWM fistulas and in some case of AT. 2/injection of saline into ST induces immediate and reproducible Y2000, G2000, et B2000 curves modifications. 3/RWM and stapes blockages provoke foreseeable stiffening and sharpening of the tympanograms at 2 kHz. 4/on the contrary, fluid removal from the cochlea induces multiple peaks curves. CONCLUSIONS: Experimentally-induced modifications at the AL either direct (stapes blockage) or indirect by AT or decrease/increase of pressure load at the cochlear interface at the footplate result in noticeable, constant, reproducible changes of curves registered at 2 kHz. The stapes behaves both as the plotter of the curves and the interpreter of the inner ear pressure.
[Multi-frequency impedance measurement and Meniere's disease. Analysis of the results of TEFLAG].
We present today our preliminary results of the TEFLAG test performed on 58 patients suffering from Meniere's disease. This test completed in 1993 has already led to a 4-stage classification of noise induced hearing losses. On the one hand, it is based on the morphological study of susceptance B curves, and on the other hand, on the study of the resonant frequency (RF) of the annular ligament of the stapes, provided by a multifrequential impedancemeter. The endolymphatic hydrops coming with the Meniere's disease practically always cohabits in the intercritical period with the decrease of the perilymphatic pressure of the scala vestibuli, which is shown in the morphology of Stage IV curves especially, and the decrease of the annular ligament rigidity. Inversely, during the vertigo or around, we mainly have stage I curves, and an increase of the stapes annular ligament resonant frequency (RF), testifying the labyrinthic hydrops, which is the physiopathological essence of the Meniere's disease.
Short-term effectiveness of medial efferents does not predict susceptibility to temporary threshold shift in the guinea pig.
The 2f1-f2 distorsion product (DPOAE) was measured in conjunction with contralateral noise to evaluate the short-term effectiveness of the olivocochlear efferents in guinea pigs (GPs). An attenuation effect was observed predominantly between 1 and 6 kHz when primary tones were set at 65 dB SPL (contralateral noise of 55 dB SPL). Subsequently, GPs were exposed to a 2 kHz tone of 87 dB SPL for 40 min, using DPOAEs as an estimate of cochlear sensitivity. The response of the cochlea appeared variable. In order to investigate whether effectiveness of efferents plays a role in temporary threshold shift (TTS), the responses of the cochlea to overstimulation were classified into three groups: i) clear cochlear change with complete recovery or actual TTS (group A1); ii) clear cochlear change with incomplete recovery (group A2); iii) mild or no change in cochlear function (group B). No relationship was found between the attenuation effect measured before noise overexposure and the susceptibility to TTS. Animals with a significant attenuation effect could fit into any of the three groups. In addition, the recovery from loud sound exposure was not paralleled with the changes occurring over time in the attenuation effect. Therefore, the conclusion that short-term effectiveness of medial efferents does not predict susceptibility to TTS in the GP is suggested.
Development of capacities of communication and socialization in young deaf children: utility of a common assessment protocol for implanted or hearing aid equipped children.
Pediatric cochlear implantation has attracted a growing interest among health professionals, but it has also encountered opposition on the deaf community. It is therefore incumbent upon the medical teams that carry out this procedure to furnish scientific arguments demonstrating the benefits of this technique for the age group 2 to 4 years and its innocuousness for the child's later psychological development. With this in mind, we have elaborated an assessment protocol adapted to very young deaf children, regardless of whether they have implants or hearing aids. The present report describes two tests of the protocol, chosen because they meet needs which until now have been insufficiently, or not, met. The first of these tests aims at assessing, as early as the age of two, oral and gestual production thanks to sequential images. The second test is the most original element of our psychological protocol: analysis of the child's interactional attitudes through filmed game situations. The initial results from a group of children recently implanted and from another group equipped with hearing aids are presented. These children continue to be seen at regular intervals. It is reasonable to hope that this kind of study will afford objective arguments to the debate in progress.
Preimplantation assessment of young profoundly deaf children.
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Tinnitus suppression in cochlear implant users.
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Intracochlear electrical tinnitus reduction.
Several reports have indicated that some cochlear implant patients experience a reduction in their tinnitus while listening to noise or speech. In the present study, two patients reporting bilateral tinnitus were selected from a group of adults with the Nucleus cochlear implant. They rated their tinnitus loudness and severity and completed the Tinnitus Handicap Questionnaire. The stimuli for electrical stimulation were charge-balanced pulse trains of various repetition rates (frequencies) and inter-electrode distances. A range of electrodes was chosen in each subject, including basal, medial and apical electrodes. For each condition, the hearing threshold level and the uncomfortable loudness level were determined. A range of stimulus levels between these two values were presented randomly. After each presentation, the patients rated the stimulus loudness and the tinnitus loudness on a 0 to 100 scale. These judgements were used to carefully determine the psychometric function between stimulus level and stimulus loudness, and between stimulus level and tinnitus loudness. All the parameters explored were important for maximizing the relationship between tinnitus reduction and stimulus loudness. First, the effectiveness of electrical stimulation in tinnitus reduction depended on the place along the cochlear partition. Second, a pulse rate of 125 Hz showed the greatest efficiency in terms of the current level needed to suppress tinnitus. Third, these two subjects showed rather poor performances in speech perception when using their speech processor in the usual condition and the hypothesis of an influence from tinnitus annoyance is suggested in addition to some more classical predicting factors of speech recognition in cochlear implant users.
[Sudden deafness: a randomized comparative study of 2 administration modalities of hyperbaric oxygenotherapy combined with naftidrofuryl].
Hyperbaric oxygen therapy is one of the numerous therapies which have been proposed in the management of sudden deafness. It is presumptuous to claim the efficiency of any treatment in a pathology where both the origin and the actual rate of spontaneous recovery are unknown. The grounds of therapies are therefore empirical but the need of urgent therapy is dictated by ethics. This study compares the effects of hyperbaric oxygen therapy in two groups of patients; according ot their order in randomization the subjects were treated either at a rate of 1 session or 2 sessions per day. Hyperbaric oxygen therapy was associated with infusion of Naftidrofuryl to counteract the vasoconstrictive effect of increased oxygen pressure in blood. Steroids were also administered simultaneously to avoid, for the same reasons, cerebral oedema. Normovolemic hemodilution (Dauman et al. 1983) was systemically performed in all the patients preliminarily to hyperbaric oxygen therapy, in order to reduce the haematocrit and thus facilitate blood supply. The efficiency and the side effects were similar in the two groups, provided that some principles in the selection and the monitoring of the patients were respected. The rate of 2 sessions of hyperbaric oxygen therapy per day has obvious advantages in view of health policy, but it requires the hospitalization of the patient and should be restricted to the younger subjects.
[Value of the association of normovolemic dilution and hyperbaric oxygenation in the treatment of sudden deafness. A retrospective study].
The multiple treatments of sudden deafness shows how this pathology still remains quite unknown. The authors present a retrospective study of 87 patients treated by normovolemic hemodilution associated to hyperbaric oxygenation. They obtain a total à 60% of significant recovery (ratio between hearing gain and initial hearing loss, above 25%) and in severe hearing loss (threshold between 70 and 90 dB) 60% of good results (ratio above 50%). The importance of the initial form of audiogram and the presence of dizziness as prognostic factors is not confirmed. On the other hand, the evolution of tinnitus is correlated with the deafness and it is a supplementary means to evaluate the therapeutic efficiency. Moreover the persistence of tinnitus represents an important after effect. Sudden deafness still remains a medical emergency and the delay for carrying out any treatment should be as short as possible. On the other hand it is possible to reduce hospital stay by two sessions of hyperbaric oxygenation per day.
[Tinnitus: peripheral and central aspects].
Tinnitus is often related to a peripheral impairment which seems to trigger an abnormal autonomous functioning of the central auditory system. Moreover peripheral stimulations may diminish, and even suppress their perception, either through masking or through inhibition of an aberrant neuronal activity. Here we present an experimental model of peripheral deafferentation in which a decrease of neurochemical activity is observed in the brainstem auditory nuclei, followed by a progressive recovery after the peripheral destruction. This activity could represent a central morphofunctional correlate of tinnitus. Development of experimental models of tinnitus must be continued. Such models should allow the study of the basic physiological mechanisms behind tinnitus and suggest some therapeutic approaches which could be objectively evaluated.
Electrocochleography: applications and limitations in young children.
Electrophysiological measurements of auditory function are especially indicated in children who are difficult to test by behavioral audiometry. This report is concerned with transtympanic electrocochleography (ECochG) findings in young children (0-3 years) who were examined over the last 6 years in order to extend behavioral audiometric data. On an average, 25% of the children tested with auditory brainstem responses (ABR) needed general anesthesia and were therefore also investigated with ECochG (n = 65). These ECochG children often showed developmental retardation, and behavioral audiometry was doubtful or not possible in 60% of them. ECochG thresholds were generally similar on both ears. Despite general agreement between thresholds obtained by ECochG and behavioral audiometry, differences were found in both directions, ECochG being better or worse than hearing in several children. Detection of severe threshold elevation and low frequency residual hearing remain major limitations of ECochG in the early diagnosis and rehabilitation of deafness in young children.
Betahistine dihydrochloride versus flunarizine. A double-blind study on recurrent vertigo with or without cochlear syndrome typical of Menière's disease.
This study was designed to compare the efficacy and safety of betahistine dihydrochloride and flunarizine. All patients included in this multicenter, double-blind, randomized trial showed a specific pattern of vertigo, i.e. recurrent paroxysmal vertigo with or without the cochlear symptoms typical of Meniere's disease. Fifty-five patients were treated for 2 months (28 in the betahistine group and 27 in the flunarizine group). Analysis of intra-group symptom changes demonstrated a greater efficacy for betahistine. Statistically significant decreases in duration and severity of attacks, and in the presence of vegetative symptoms were seen in the betahistine group after the first and second months of treatment, whereas in the flunarizine group this was the case only at the end of the first month of treatment. Furthermore in the betahistine group, statistically significant decreases occurred for the other major criteria, including number of attacks, evidence of vestibular dysfunction, and presence of cochlear symptoms. Adverse effects were similar to those reported in previous studies of both products: stomach pains only with betahistine, and drowsiness, asthenia, and depression with flunarizine.
[Current role of electrocochleography].
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[Clinical value of tuning curves or frequency selectivity curves].
A simplified method, useful in clinical practice, is described in order to study the frequency selectivity in various conditions. The patient is asked to indicate the levels of pure tones which are necessary to mask completely the perception of an intermittent probe. The resulting psychoacoustic tuning curves are characterized by a more or less narrow bandwidth which reflects the ability to resolve simultaneously presented sounds. Several circumstances where these tuning curves are helpful, are presented: assessment of tinnitus, Menière's disease, unclear impairment of speech intelligibility. Therefore, this technique appears as a valuable tool which can be used in addition to the usual audiometric and electrophysiological tests battery.