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Biomedical subjects

M Dordain

Publications and source records attributed to M Dordain.

At least 19 recordsLinked to original sources
PubMed2000

Middle ear influence on otoacoustic emissions. I: noninvasive investigation of the human transmission apparatus and comparison with model results.

Evoked otoacoustic emissions (EOAEs) are generated within the cochlea in response to external sounds, and they can be acoustically detected in the external auditory meatus after backward propagation through the middle ear. In addition to being used to probe the cochlear mechanisms, they are expected to be sensitive to minute changes in middle ear impedance. Systematic measurements of the changes in the vectorial components of EOAEs were carried out after various manipulations of the human middle ear in order to characterize the influence of stiffness and inertia of the stapes and tympanic-membrane systems. For this purpose, stapedius muscle contractions were elicited by high-level contralateral sound, controlled changes in middle ear pressure (range +/-100 daPa) were produced and the tympanic membrane was loaded with water droplets. A computer model of the middle ear network was implemented using a standard lumped-element electric analog of the middle ear (Zwislocki's model). Forward and backward transmission changes were simulated and model predictions were compared to experimental data. Apart from the case of positive middle ear pressures, a close qualitative correspondence was found between model and real-ear results. Each of the effects was characterized by a unique pattern of phase and magnitude changes as a function of frequency, in relation to the mechanical characteristics of the involved subsystem (i.e. stapes stiffness, tympanic-membrane stiffness or mass) and its resonance properties. Owing to their high sensitivity, EOAEs could be helpful for an accurate individual multifrequency analysis of middle ear impedance by comparisons under rest and test conditions.

Acoustic Impedance Tests↗
PubMed2000

Middle-ear influence on otoacoustic emissions. II: contributions of posture and intracranial pressure.

Although it seems likely that body tilt or surgically provoked variations in intracranial pressure (ICP) can result in variations of intralabyrinthine pressure, the channels for pressure transmission remain controversial and the reasons why evoked otoacoustic emissions (EOAEs) exhibit attendant modifications are unclear. The theoretical framework implemented in the companion paper [Avan et al. part I, 2000] provides sensitive and non-invasive means to identify the middle-ear mechanism(s) entailed in EOAE changes. It was thus applied to analyze the influence of posture on EOAE phases and magnitudes as a function of frequency, in a series of experiments involving body tilt from sitting to supine (0 degrees or -30 degrees ). Controlled ICP variations were surgically carried out in a series of hydrocephalic patients and the resulting EOAE changes were compared to posture data and model predictions. In all cases, the EOAE changes closely resembled those due to an increase in the stiffness of the stapes' annular ligament, in keeping with the assumption that ICP gets transmitted to intralabyrinthine spaces and modifies the hydrostatic load on the stapes, thereby influencing EOAE features. A small additional contribution of middle-ear pressure to EOAE changes was identified in addition to the main stapes component. Dynamical EOAE measurements showed that sudden ICP changes were transmitted to the inner ear within 8-30 s. The high sensitivity of EOAE phases below 2 kHz to ICP changes, together with the absence of any significant confounding middle-ear effect, favors EOAEs for a reliable non-invasive monitoring of ICP and intralabyrinthine pressures.

Acoustic Impedance Tests↗
PubMed2000

[Multiple eccrine hydrocystomas of the eyelids in the framework of Schöpf syndrome. A case report].

Schöpf-Schultz-Passarge syndrome is a rare ectodermal dysplasia described by Schöpf in 1971. The disease is characterized by hypodontia, hypotrichosis, palmoplantar keratoderma, hypoplastic nails and eyelid hydrocystomas. We report the case of a 71-year-old man, the first French description of this syndrome, who remarkably presented all the signs. The patient also had skin tumors, multiple eccrime hidrocystomas and aspectific macular degeneration. A review of the literature is discussed.

Aged↗
PubMed1997

[Non-invasive monitoring of intracranial pressure changes through the ear].

Otoacoustic emissions are low energy vibrations generated by the inner ear during the physiologic process of hearing. The authors measured transiently evoked otoacoustic emissions in normal hearing individuals placed in Trendelenburg position and during diagnostic elevation of intracranial pressure in neurosurgical patients. In Trendelenburg position and at elevated intracranial pressure and reproducible phase shift of otoacoustic emissions could be observed. This phase shift was linear to the pressure increase of intracranial liquids. According to the hypothesis of the authors intracranial pressure increase is transmitted to the inner ear (possibly by the cochlear aqueduct) and thereby the mechanical load on the stapes footplate is elevated. This, in turn, causes a stiffening of the annular ligament which changes the angle of the impedance vector and thereby the phase of the whole vibrating system. By measuring the phase of otoacoustic emissions it is possible to monitor intracranial pressure in various clinical states.

Ear, Inner↗
PubMed1997

Dual processing of open- and closed-class words.

A series of articles in the past two decades has suggested differential processing of open- and closed-class lexical items by normal adults. Difficulties in replicating a crucial study (Bradley, 1978), however, have weakened the dual route hypothesis. We matched 16 French open-class items to 16 closed-class items for phonological structure, world length, and relative word frequency. Three agrammatic aphasics revealed strikingly more phonological errors on closed-class than open-class items. Dysfluencies were greater on closed-class items and contributed to greater overall reading time for the closed-class words, consistent with a two-route model for the production of closed- and open-class lexical items in Broca's aphasics and, thus, normals.

Aged↗
PubMed1996

Picture confrontation oral naming: performance differences between aphasics and normals.

Oral confrontation naming was compared in 108 normal subjects controlled for education, age, and gender and in 18 aphasic patients for the same set of 115 pictures. Demographic variables influenced both normals' and aphasics' performance. However, the nature of aphasics' misnamings on the one hand and the differential effects of characteristics of pictures and words on normals' and aphasics' responses on the other indicated specific deficits in patients. The classical hypothesis that aphasics' misnamings and the production of word associations by normals should rely on similar mechanisms (Rinnert & Whitaker, 1973) is questioned. Nondominant responses observed in normals accounted for a larger proportion of verbal errors than associates to target words.

Adult↗
PubMed1996

Otoacoustic emissions: a new tool for monitoring intracranial pressure changes through stapes displacements.

Changes in hydrostatic intracranial pressure (ICP) are thought to be transmitted to cochlear liquids, thereby altering the mechanical load on the stapes footplate. Hence the stiffness of stapes' annular ligament is expected to reflect ICP changes. Corresponding middle-ear transmission changes have been assessed using click-evoked otoacoustic emissions (EOAE) in two experiments. The first one was performed in 22 normal human subjects submitted to posture changes. In the second one, controlled ICP increases were applied to 18 patients in neurosurgery operating theater. EOAEs were monitored in these subjects throughout the experiments and their phases and amplitudes were analyzed as a function of frequency. ICP affected EOAEs in a systematic manner in both experiments, i.e., the main effect of ICP increase was phase lead of EOAE components below 2 kHz without any significant amplitude or frequency shift. Their variations were much more evident than the modifications in middle-ear impedance assessed by standard impedance or admittance measurements. The second experiment led to a quantitative linear relationship between ICP and EOAE phases. It demonstrated that the sensitivity of EOAE phase monitoring technique proves to be quite high, i.e., 55 daPa increases in ICP are readily detected in all subjects. The results are consistent with the predictions of classical middle-ear models as to the transmission alterations induced by ICP-related changes in the stiffness of the annular ligament of the stapes. Non-invasive monitoring of ICP in patients with hydrocephalus treated with ventriculo-peritoneal shunts might be attempted with this technique, although it is restricted to patients with detectable EOAEs (i.e., about 50% in this series).

Acoustic Stimulation↗
PubMed1995

Calculation and number processing in mild Alzheimer's disease.

Calculation and number processing abilities in 17 patients suffering from a mild form of dementia of Alzheimer's type (DAT) were studied by means of a standardized multitask assessment battery, the EC301 (Deloche et al., 1994). Patients were selected from a larger sample by using a specific visuo-perceptive task to control the confounding effects of deficits in analysing digit serial order. Language and memory skills were evaluated by means of standardized testing procedures. The EC301 overall score showed impaired performance in 12 cases. Calculation and number processing scores were highly correlated with Mini-Mental State Examination and language performance. However, multiple single-case analyses indicated heterogeneous patterns of preserved/impaired abilities with respect to the three cognitive areas under investigation (calculation, memory, and language) and to the different components of the calculation and number processing system.

Aged↗
PubMed1994

Calculation and number processing: assessment battery; role of demographic factors.

This paper describes the structure and contents of EC301, a standardized testing battery for the evaluation of brain-damaged adults in the area of calculation and number processing. The battery was administered to 180 normal subjects stratified by education (3 levels), age (3) and gender. EC301 is composed of a large variety of tasks dealing with basic arithmetic skills, and their linguistic, spatial, and mnesic dimensions. The three main notational systems for numbers--Arabic digits, written verbal, and spoken verbal number forms--are explored. Analysis of error rates indicated the effect of some demographic factors (principally, education; incidentally, gender) on normal performance in some tasks.

Adult↗
PubMed1988

Agrammatism in sentence production without comprehension deficits: reduced availability of syntactic structures and/or of grammatical morphemes? A case study.

A French-speaking patient with Broca's aphasia--following a left-hemisphere lesion involving the sylvian region but sparing Broca's area--is presented. Like G. Miceli, A. Mazzuchi, L. Menn, and H. Goodglass's (1983, Brain and Language, 19, 65-97) case 2, this patient produces agrammatic speech in the absence of any comprehension deficit. Unlike Miceli's patient, though, agrammatic speech can be observed in all sentence production tasks (from spontaneous speech to repetition, oral reading, and writing) whereas production of individual words--be they open class or closed class--is almost always intact. On the basis of extensive (psycho)linguistic testing, it is argued that this patient's deficit is not central and not crucially syntactic (at least) at the level of knowledge but seems to disrupt specifically those (automatic?) processes responsible for both retrieval and production of free-standing grammatical morphemes whenever they have to be inserted into phrases and sentences.

Aphasia↗
PubMed1981

[Speech and language after operation for labiopalatovelar cleft on 100 children, of whom 37 were more than 4 years old (author's transl)].

Operations for labiopalatovelar cleft have been conducted on 100 children, of whom 37 were under 4 years of age, at the Hôtel-Dieu hospital in Clermont-Ferrand, since 1970. According to the concept developed by Célesnik, refection of the soft palate is carried out at 18 months, without closure of the palate. The children were followed-up by a multidisciplinary team from birth to 6 years. Those children with labiopalatovelar clefts had normal speech and language after 6 years, without re-education in a quarter of them. Another quarter had slight nasal intonation but no articulation problems. Half of the children with a velar cleft only had normal speech and language not requiring re-education, after 6 years.

Child, Preschool↗
PubMed1978

[Tachylalia: clinical and acoustic study of 149 subjects (author's transl)].

Speech was studied subjectively (listening to recordings) and objectively (measurement of durations) in 67 Parkinsonians, 10 subjects with neurological disorders and 72 psychiatric patients. Acceleration of speech was greatest in the Parkinsonians (8.5 syllables per second). The total duration of a sentence read by several of tachylalic Parkinsonians was the same as that of normal control subjects reading as fast as they could. The duration of the pauses between words varied greatly in all categories of subjects. Almost half of the tachylalic Parkinsonians (10 out of 23) had a speaking time (excluding pauses) shorter than the shortest duration recorded among same-age normal controls. The authors attach particular significance to the cases in which tachylalia is observed in the absence of lesions in the central gray nuclei. These cases suggest that speech automatisms are regulated at several levels.

Adolescent↗