Biomedical subjects

P Avan

Publications and source records attributed to P Avan.

At least 19 recordsLinked to original sources

PubMed2006

[The cochlea in Fabry disease: a sensorineural hearing loss model of vascular origin?].

PURPOSE: Fabry disease is an inborn error of metabolism due to a deficient activity of the lysosomal enzyme alpha-galactosidase A. The enzyme defect leads to the systemic accumulation of neutral glycosphingolipids in tissues, mainly in the vascular endothelium. STRONG POINT: The aim of this paper is to present a review of the auditory manifestations in Fabry disease, and to discuss hypothesis on the vascular origin of deafness. PERSPECTIVES: Sensorineural hearing loss in Fabry disease could be the first documented vascular pathology of the inner ear.

Cochlea↗

PubMed2006

[Adenocarcinomas of the ethmoid sinus: retrospective analysis of prognostic factors].

OBJECTIVES: Determinate the different prognostic factors of survival in ethmoidal sinus adenocarcinomas (ADK). MATERIAL AND METHODS: 60 patients with ethmoidal sinus ADK. 59 men and one woman. Average of 62.2 years (41-82). Retrospective study between 1985 and 2005. The following data were analyzed: exposure time to wood dust, disease incidence, primary clinical symptoms and ASA score. Radiological data were recovered by tomodensitometry and magnetic resonance imaging. Histological groups were described. TNM classification according to UICC 2002 and Roux/Brasnu was established on clinical and radiological constatations. Different treatments used were analyzed. Estimate of survival rate and impact of different prognostic factors were based on Kaplan-Meier actuarial method and multivariate analysis. RESULTS: Incidence rate was 2.86 patients a year. Exposure average time to wood dust was 25.6 years (2-44). T3/T4 stages were predominant (66.7%). the survival rate was 46.5% at 5 years. The survival rate was significantly superior respectively in T1 and T2 stages than in T3 and T4 stages, and in T4a than in T4b stages. Extension of the lesion to the sphenoid sinus was revealed as a significant bad prognostic factor. The ASA score and the exposure time to wood dust were not identified as statistically significant prognosis factors. CONCLUSION: Survival factors of ethmoïd sinus ADK were T stage and the extension of the tumor to the sphenoid sinus. On the results of this study, we consider that extension in sphenoïd sinus could be include in TNM classification of ethmoïd sinus adenocarcinomas.

Adenocarcinoma↗

PubMed2005

Classification of technical pitfalls in objective universal hearing screening by otoacoustic emissions, using an ARMA model of the stimulus waveform and bootstrap cross-validation.

Transient-evoked otoacoustic emissions (TEOAE) are widely used for objective hearing screening in neonates. Their main shortcoming is their sensitivity to adverse conditions for sound transmission through the middle-ear, to and from the cochlea. We study here whether a close examination of the stimulus waveform (SW) recorded in the ear canal in the course of a screening test can pinpoint the most frequent middle-ear dysfunctions, thus allowing screeners to avoid misclassifying the corresponding babies as deaf for lack of TEOAE. Three groups of SWs were defined in infants (6-36 months of age) according to middle-ear impairment as assessed by independent testing procedures, and analyzed in the frequency domain where their properties are more readily interpreted than in the time domain. Synthetic SW parameters were extracted with the help of an autoregressive and moving average (ARMA) model, then classified using a maximum likelihood criterion and a bootstrap cross-validation. The best classification performance was 79% with a lower limit (with 90% confidence) of 60%, showing the results' consistency. We therefore suggest that new parameters and methodology based upon a more thorough analysis of SWs can improve the efficiency of TEOAE-based tests by helping the most frequent technical pitfalls to be identified.

Acoustic Impedance Tests↗

PubMed2004

[Contribution of cognitive and behavioral therapy for patients with tinnitus: implication in anxiety and depression].

OBJECTIVES: Tinnitus is a common otologic symptom but, despite important advances in the evaluation and management of such symptom, ENTs often fail to address tinnitus properly. Some tinnitus patients report that tinnitus interferes with activities of daily living, such as reading, social interactions, sleep, concentrating on complex tasks. Anxiety and depression are current major disorders associated with tinnitus. Many theories exist regarding mechanisms of tinnitus origin. A number of publications favors the theory of discordant dysfunction of inner or outer hair cells of the organ of Corti. Nevertheless, some authors insist on the possible role of the central auditory pathways. Multiple functional connections between auditory system, limbic system, autonomic nervous system seem crucial in the development of tinnitus. The aim of this paper is to present a new approach in France of tinnitus treatment by cognitive-behavioral therapy (CBT). MATERIAL AND METHODS: 96 patients with chronic and intense tinnitus were included in the study (38 females, 36 males, mean age 48 years). A CBT was developed after a clinical evaluation based on standardized questionnaires. RESULTS: The two main results are: (i) the importance of anxiety and depression in this population, (ii) the amelioration of tinnitus perception in 750f the included patients. CONCLUSION: CBT shows promise as a treatment of tinnitus-related distress.

Anxiety↗

PubMed2003

[Adrenal insufficiency after treatment of nasal polyposis].

OBJECTIVE: Assessment of hypothalamic-pituitary-adrenal (HPA) axis after long term and uncontrolled corticosteroid treatment in nasal polyposis. PATIENTS AND METHODS: A short synacthen test was performed in ten patients who received uncontrolled doses of corticosteroids in a population of 128 patients treated for nasal polyposis. RESULTS: Mean yearly dose of oral prednisone administered in short-term treatment varied between 1280 and 7300 mg. Mean daily dose of inhaled beclomethasone varied between zéro and 2000 microg. Morning plasmatic cortisol was abnormal in seven the patients before and after the stimulation (respectively 140 nmole/l and 359 nmole/l). DISCUSSION: High and uncontrolled doses of corticosteroids in nasal polyposis affect HPA axis.

Adrenal Insufficiency↗

PubMed2002

[Idiopathic sudden deafness].

PURPOSE: Sudden idiopathic deafness is a sensorineural hearing loss with no recognized causes at the time of onset. The impairment site is usually localized in the cochlea, but some cases of retrocochlear lesions (e.g., cerebellopontine angle tumors, degenerative neural diseases, neuraxial ischemic lesions) can induce sensorineural deafness. The medical management of patients presenting with sudden deafness aims at detecting a causal mechanism, and at administering emergency therapeutic drugs. The diagnosis of idiopathic sudden deafness can be definitely made when no causes are found. Usually, the impairing mechanism involves the cochlea. The pathophysiology of this sensorineural alteration is still unknown. It is most likely that several mechanisms are associated together, their common point being an impairment to the feedback loop of the organ of Corti. CURRENT KNOWLEDGE AND KEY POINTS: It is very likely that reactivation of neurotropic viruses and/or cochlear ischemia are frequent etiologies. Whatever the cause, the treatment is to be administered urgently, and consists of a high-dose corticotherapy at the least. Other treatments have never really proven to be effective. It is secondarily checked that no retrocochlear pathological processes, such as a cerebellopontine angle tumor, is present, in particular in young people. FUTURE PROSPECTS AND PROJECTS: One of the current objectives is to determine when cochlear ischemia is involved, in a mini-invasive manner, such as with laser Doppler flowmetry, so that the treatment can be optimized. From a therapeutic point of view, early acoustic protection has been proven to be effective in cases of cochlear ischemia in small laboratory animals. Its efficacy in case of sudden deafness, non-exclusive of other causes than ischemia, is being assessed in a multicentric project.

Adrenal Cortex Hormones↗

PubMed2001

Functional anatomy of auditory brainstem nuclei: application to the anatomical basis of brainstem auditory evoked potentials.

Brainstem auditory evoked potentials (BAEP) are used routinely in clinical practice to evaluate the normality of the lower auditory system. The objective of this review is to describe the functional anatomy of the structures implicated in BAEP generation (cochlear nerve and the auditory brainstem nuclei). Indications and results of BAEP in clinical practice are presented and correlated with auditory structures, which generate each waveform of BAEP.

Auditory Pathways↗

PubMed2001

The behavior of evoked otoacoustic emissions during and after postural changes.

Click-evoked and stimulus frequency otoacoustic emissions (CEOAEs and SFOAEs, respectively) were studied in humans during and after postural changes. The subjects were tilted from upright to a recumbent position (head down 30 deg) and upright again. Due to the downward posture change, CEOAEs showed a phase increase (80 deg at 1 kHz) and a level decrease (0.5 at 1 kHz), especially for frequency components below 2 kHz. For SFOAEs, the typical ripple pattern showed a positive shift along the frequency axis, which can be interpreted as a phase shift of the inner-ear component of the microphone signal (90 deg at 1 kHz). This also occurred mainly for frequencies below 2 kHz. The altered posture is thought to cause an increase of the intracranial pressure, and consequently of the intracochlear fluid pressure, which results in an increased stiffness of the stapes system. The observed emission changes are in agreement with predictions from a model in which the stiffness of the cochlear windows was altered. For CEOAEs, the time to regain stability after a downward turn was of the order of 30 s, while this took about 20 s after an upward turn. For SFOAEs, this asymmetry was not found to be present (about 11 s, both for up- and downward turns).

Adult↗

PubMed2001

Origin of cubic difference tones generated by high-intensity stimuli: effect of ischemia and auditory fatigue on the gerbil cochlea.

Cubic difference tone (CDT) otoacoustic emissions are thought to arise from the feedback loop allowing outer hair cells to enhance the sensitivity and tuning of the organ of Corti. The existence of residual CDTs during complete cochlear ischemia is therefore disturbing. That stimulus intensities must exceed 50-60 dB SPL for residual CDTs to be recorded and for level notches to be present in CDT growth functions is often cited as evidence for a two-component, "active/passive" model: one component, the residual one, would originate from a passive, hardly vulnerable mechanism and thus be unsuitable for hearing screening purposes. This model was probed in gerbil ears after complete interruption of the cochlear blood flow. Cochlear potentials and CDTs were controlled simultaneously through continuous monitoring of CDT level and phase for 50 and 60 dB SPL stimuli and group-delay measurements. After a clear initial decay, CDT levels elicited at 60 dB SPL plateaued for several minutes at about 20 dB below initial level, and when early level notches were observed, CDT phase changes remained minor. The CDT group delays decreased by less than 30%. Later CDT level notches were associated with sharp phase reversals but the similarity between CDT characteristics before and after a notch was hardly consistent with a two-component interpretation. When mild sound overexposure (pure tone, 90-95 dB SPL, 15-30 min) had been performed prior to ischemia, little or no ischemic CDT came from the frequency bands where auditory fatigue had been detected (within 1 kHz), irrespective of the stimulus intensity. It suggests that instead of being passive, residual ischemic CDTs were vulnerable and produced according to a near-normal tonotopy by the same mechanisms that were sensitive to auditory fatigue. All the results lined up with a simple feedback model of cochlear function assuming a single CDT source related to mechano-electrical transduction in outer hair cells. More parsimonious than a two-component model, it posits that although early stages of ischemia dramatically impair the overall performance of the cochlea, the nonlinear mechanical stages responsible for the existence of CDTs keep working albeit at higher intensities.

Acoustic Stimulation↗

PubMed2001

Catheter-related upper extremity deep venous thrombosis in cancer patients: a prospective study based on Doppler US.

PURPOSE: This prospective study extending for more than 3 years had two objectives: (a) to use Doppler ultrasonography (US) to estimate the incidence of asymptomatic catheter-related upper extremity deep venous thrombosis (DVT) in a large population and (b) to study the effect of the catheter position as an individual risk factor for catheter-related DVT. MATERIALS AND METHODS: Between October 1995 and June 1998, a total of 145 patients who had oropharyngeal tract cancer and who were fitted with the same totally implantable central venous catheters (CVCs) were included in the study. Follow-up included (a) estimation of the position of each catheter tip on a chest radiograph obtained immediately after surgery and (b) regular monthly Doppler US screening for catheter-related DVT. RESULTS: Seventeen patients developed catheter-related DVT; 13 of them were asymptomatic. The mean interval between CVC implantation and detection of thrombosis was 42.2 days. Correct positioning of the distal catheter tip was associated with a significantly lower rate of catheter-related DVT. Only five of 87 patients with a correctly positioned distal catheter tip (ie, either in the superior vena cava or at the junction between the right atrium and the superior vena cava) developed thrombosis, compared with 12 of 26 patients with a misplaced catheter (P <.001). The side on which the CVC was implanted did not influence the catheter-related DVT rate. CONCLUSION: The rate of asymptomatic catheter-related DVT is high and could be lowered with correct initial CVC positioning.

Adult↗

PubMed2000

[Evaluation of the hypothalamo-hypopituitary axis after long-term inhalation corticotherapy for nasal polyposis].

OBJECTIVE: To assess the hypothalamic-pituitary-adrenal (HPA) axis after long-term intranasal corticosteroid treatment in nasal polyposis. PATIENTS AND METHODS: A short synacthen test was performed in 24 patients who received the highest dose of inhaled beclomethasone among a population of 392 patients treated for nasal polyposis with inhaled corticosteroid therapy and short-term oral corticosteroids. RESULTS: Mean yearly dose of oral prednisone administered in short-term treatment was 371 mg/year. The amount of short-term oral prednisone decreased during the treatment. Mean daily dose of inhaled beclomethasone was 2861 micrograms/day, decreasing during treatment. Morning plasma cortisol was normal in all patients before and after stimulation (163 +/- 44 and 1 +/- 60 micrograms/ml respectively). Nolomethasone dose and plasma cortisol level before or after stimulation. DISCUSSION: The high dose of inhaled beclomethasone used to treat nasal polyposis does not affect the HPA axis. Some authors in the literature contest the validity of short synacthen test to detect HPA axis suppression. This test does however detect severe impairments of the HPA axis in outpatients.

Administration, Inhalation↗

PubMed2000

Olivocochlear efferent vs. middle-ear contributions to the alteration of otoacoustic emissions by contralateral noise.

The medial olivocochlear efferent bundle is the key element of a bilateral efferent reflex activated by sound in either ear and acting directly on cochlear outer hair cells (OHC) via numerous cholinergic synapses. It probably contributes to regulating the mechanical activity of the cochlea. Otoacoustic emissions, being sounds emitted by the cochlea as a reflection of its activity and suppressed by efferent activation, are increasingly considered to be the privileged tool for a noninvasive assessment of the efferent reflex. However, confounding effects on otoacoustic emissions can occur. A primary influence is middle-ear muscle reflex activation, which shares common features with the effects of cochlear efferent activation. We report a systematic comparison of the responses of human otoacoustic emissions to efferent activation by low-level noise in the contralateral ear to various middle-ear manipulations (reflex contractions of the stapedius muscle induced by high-level contralateral noise; moderate middle-ear pressure changes). The profiles of level and phase changes of otoacoustic emissions as a function of frequency were highly specific to the origin of the effects. The changes induced by middle-ear manipulations matched the predictions computed from a standard lumped-element middle-ear model, with one or two peaks around the resonance frequency(ies) of the involved subsystem, stapes or tympanic membrane. In contrast, the efferent effect was completely different, exhibiting a broadband-level suppression associated with a small phase lead. We propose that a careful vector analysis of otoacoustic emission modifications enables the identification of the contribution of the efferent reflex without ambiguity even when it is mixed with middle-ear effects. Thereby, otoacoustic emissions can be used more reliably as noninvasive probes of efferent olivocochlear function.

Acoustic Stimulation↗

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

Spatio-temporal distribution of cellular retinoid binding protein gene transcripts in the developing and the adult cochlea. Morphological and functional consequences in CRABP- and CRBPI-null mutant mice.

The expression patterns of the mouse cellular retinoid binding protein genes were investigated by in situ hybridization analysis in the inner ear from 10.5 days post coïtum (dpc) up to the adult stage. The cellular retinoic acid binding protein II (CRABPII) and cellular retinol binding protein I (CRBPI) were present in a widespread and abundant pattern in cochlear structures during embryogenesis. Expression of the cellular retinoic acid binding protein I (CRABPI) is restricted during development in Kölliker's organ whilst cellular retinol binding protein II (CRBPII) is only visible after birth with a ubiquitous distribution in most regions of the cochlea including nervous components. No CRABP or CRBP transcripts were observed in the auditory receptors. Morphological observations of CRBPI- and CRABPI/CRABPII-null mutant fetus at 18.5 dpc do not show any structural modification at the level of the organ of Corti. Furthermore, electrophysiological tests performed by measuring distorsion-product otoacoustic emissions and auditory brainstem evoked responses did not present significant alteration of the auditory function for the different types of mutants. The expression of retinoid binding proteins in cochlear structures during embryogenesis could suggest important roles for these proteins during ontogenesis and morphogenesis of the inner ear. Despite these observations, morphological and functional data from mutant mice did not present obvious modifications of the cochlear structures and auditory thresholds. It is therefore unlikely that CRABPs and CRBPI are directly involved in development of the cochlea and hair cell differentiation.

Age Factors↗

PubMed2000

On the spectral periodicity of transient-evoked otoacoustic emissions from normal and damaged cochleas.

The spectral quasi-periodicity of transient-evoked otoacoustic emissions (TEOAE) is well acknowledged since Zwicker described a preferred spacing of 0.4 bark between consecutive peaks in the spectrum of otoacoustic emissions from normal ears. While there is scarce evidence of any anatomical reason for this regularity, several functional models of the cochlea have predicted that the structure of emission spectra reflects important characteristics of cochlear filters. In an attempt to check such predictions, the average regularity of TEOAE spectra was studied in three groups of human subjects, normally hearing adults, healthy neonates, and adults suffering from noise-induced hearing loss. Significant differences in emission periodicities were found. Around 1 kHz, the preferred spacing was close to 130 Hz in normally hearing adult ears and neonates. In contrast, no clear periodicity was found in the group of damaged ears, even though they had clinically normal pure-tone audiometry below 2 kHz. Around 4 kHz, the preferred spacing was close to 240 Hz in normal adults and neonates, whereas TEOAEs were absent in many impaired ears. A phenomenological model assuming that TEOAEs stem from the responses of a slightly disarrayed bank of highly tuned filters predicts that the filter width would be the same in healthy young adults and neonates. In contrast, ears suffering from high-frequency hearing loss could exhibit early damaged filters. The proposed method might provide an objective assessment of parameters otherwise difficult to evaluate, especially in neonatal cochleas.

Adult↗

PubMed2000

The behavior of spontaneous otoacoustic emissions during and after postural changes.

Spontaneous otoacoustic emissions (SOAEs) were studied in humans during and after postural changes. The subjects were tilted from upright to a recumbent position (head down 30 degrees) and upright again in a 6-min period. The SOAEs were recorded continuously and analyzed off-line. The tilting caused a change in the SOAE spectrum for all subjects. Frequency shifts of 10 Hz, together with changes of amplitude (5 dB) and width (5 Hz), were typically observed. However, these changes were observed in both directions (including the appearance and disappearance of emission peaks). The most substantial changes occurred in the frequency region below 2 kHz. An increase of the intracranial pressure, and consequently of the intracochlear fluid pressure, is thought to result in an increased stiffness of the cochlear windows, which is probably mainly responsible for the SOAE changes observed after the downward turn. The time for the spectrum to regain stability after a postural change differed between the two maneuvers: 1 min for the downward and less than 10 s for the upward turn.

Cochlea↗

PubMed1999

Vulnerability of the gerbil cochlea to sound exposure during reversible ischemia.

Cochlear ischemia induces a sensorineural hearing loss, in part through a fast functional impairment of outer hair cellls. Assuming that the cochlea is rendered fragile during ischemia and reperfusion and that stimulation itself can jeopardize its functional recovery, we used a model of reversible selective cochlear ischemia in Mongolian gerbils to establish what type of sound exposure can be deleterious during and immediately after reversible ischemia. Several groups of gerbils were used, with different ischemia durations and levels of sound exposure. Control groups were only exposed to tones at 80 and 90 dB SPL during 30 min, while other groups underwent complete and fully reversible blockage of the labyrinthine artery, during 5.5 or 8 min, and were exposed to 60 or 80 dB SPL tones during 30 min. The amount of ischemia and reperfusion was measured by means of laser Doppler velocimetry, whereas outer hair cells' function was continuously monitored through distortion-product otoacoustic emissions (DPOAEs). The losses of DPOAE levels after 8 min transient ischemia and 60 dB SPL exposure were as large as those induced by 80 dB SPL exposures combined with 5.5 min ischemia, or 90 dB SPL exposures without ischemia, with a maximum loss around 25-30 dB, half an octave above the stimulus frequency. These results give evidence for an extremely high cochlear vulnerability to low-level sound exposure when associated with reversible ischemia. This vulnerability may have important clinical consequences in patients with cochlear circulatory disturbances.

Animals↗