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Biomedical subjects

E Truy

Publications and source records attributed to E Truy.

At least 37 records · Page 2Linked to original sources
PubMed1999

Loudness growth functions and EABR characteristics in Digisonic cochlear implantees.

Electrically evoked auditory brainstem responses (EABRs) and loudness functions were measured in 14 subjects equipped with an MXM Digisonic cochlear implant. EABRs were evoked by 75-Hz pulse trains presented on the apical electrode. Loudness functions at the same rate and at a rate more conventional for psychoacoustic measurements (300 Hz) were measured using a categorical loudness-scaling procedure. The results revealed a significant difference in the loudness functions measured at 75 and 300 Hz, loudness increasing more steeply with stimulus intensity for the latter rate. Significant correlations between EABR wave V thresholds and perceptual thresholds measured at both 75 and 300 Hz were observed. Furthermore, in 8 out of the 14 patients, EABR wave V saturated at a stimulus level corresponding precisely to the loudest bearable, i.e. "Too loud" level for the 300-Hz stimulation rate; this same level corresponded to the "Comfortable" loudness level for the 75-Hz stimulation rate. On average, an almost linear relationship was observed over the first half of the loudness range between the stimulus intensity, expressed as a pulse duration in log units, and wave V amplitude in dB. Although further investigation is required before maximum comfort levels can be predicted reliably from EABR measures in individual subjects, these results indicate new directions regarding the estimation of perceptual dynamic range limits on the basis of EABR measures in cochlear implantees.

Adult↗
PubMed1999

[Acoustic neuroma in children. Report of 5 cases].

In this report, we present five cases of acoustic neuroma in children; one of them concern a case of neurofibromatosis 2. The most common symptom is a deafness, but it can also be revealed by a tinnitus, a vertigo, a facial nerve paralysis or headache. Diagnosis is confirmed by T1 and T2-weighted MRI with intravenous infusion of gadolinium. The deals of the treatment are tumor's control and preservation of the hearing and facial nerve functions. The means used are either microsurgery with a preference for posteriors approaches to translabyrinthic one, or radiosurgery with gamma knife which seems to be a promising technique for stades II and III tumors. Only children with small acoustic neuroma and good hearing can be simply watched. In neurofibromatosis 2, acoustic neuromas are bilateral and can be associated with other neuromas and cutaneous or ophtalmologic symptoms. Surgery is indicated in first on the side of the biggest tumor or the worst hearing function. Only a few patients well selected may benefit from an auditory brainstem implant.

Adolescent↗
PubMed1998

Comprehension of language in congenitally deaf children with and without cochlear implants.

The consequences of profound early deafness on oral language in children are drastic. The modern cochlear implant (CI) has been shown to enhance speech production skills in prelingually deaf children. Many factors may contribute to a poor or an excellent outcome, making it difficult to compare groups of children wearing or not wearing cochlear implants. The present study compared receptive language levels in matched pairs of children from CI group and non-CI groups. The pre-op receptive language development curve suggest a possible growth over time with the maturation and the speech therapy. Comparison showed that the slope for post-op CI children to be greater than for non-CI children, and that this difference is statistically significant, and that the slope for CI children to be greater post- than pre-operatively. The main conclusion is that receptive language scores grow significantly higher over time after surgery in CI than in pair-matched non-CI children, despite better initial pure tone audiometric thresholds of the latter.

Age Factors↗
PubMed1998

[Diagnostic criteria for progressive necrotizing external otitis. Are scintigraphic findings reliable?].

OBJECTIVES: Determine the role of 99m technetium scintigraphy for diagnosis in progressive necrotizing external otitis and assess the diagnostic criteria of this disease. METHOD: A retrospective study was conducted in 16 patients hospitalized for suspected progressive necrotizing external otitis. Patient characteristics, clinical features, imaging findings and disease course were recorded in order to evaluate the classical criteria of diagnosis. RESULTS: The clinical course and complementary test results showed that 99m technetium scintigraphy lacked specificity for progressive necrotizing external otitis. These findings are in disagreement with those reported in the literature. CONCLUSION: Patient characteristics and clinical course are key elements for early diagnosis of this disease. Scintigraphy findings are contributive only when bone lysis (which occurs late) can be evidenced. A prospective study would be required to confirm the lack of specificity of scintigraphy in progressive necrotizing external otitis.

Adult↗
PubMed1998

Cochlear implant performance and electrically-evoked auditory brain-stem response characteristics.

OBJECTIVES: The purpose of this study was to find a correlation between cochlear implant performances in phoneme discrimination and activity of the brain-stem. METHODS: Electrically-evoked auditory brain-stem responses (EABRs) and speech recognition performances were measured in 17 patients implanted with an MXM Digisonic DX10 cochlear implant. Speech recognition performances without lip-reading were tested using lists of isolated French words containing 3 phonemes. RESULTS: The results indicated statistically significant correlations between phoneme correct-identification scores and the following EABR variables: wave V latency, wave II-V latency interval and wave III-V latency interval. These results, indicate that up to about 48% of the variance in isolated word recognition without lip-reading can be accounted for by EABR variables. CONCLUSION: The quality of brain-stem functioning influences central processes in phoneme discrimination.

Adult↗
PubMed1998

Correlation between electrical auditory brainstem response and perceptual thresholds in Digisonic cochlear implant users.

OBJECTIVES: To examine the relationships between psychophysical perceptions and the electrically evoked auditory brainstem responses (EABRs) in multichannel cochlear implant (CI) users and to determine the effectiveness of EABRs in electrode failure. DESIGN: A descriptive study reported the EABR characteristics while the different electrodes were activated. Characteristics of the EABR and of the perceptual measures served as compared variables in a correlational study. SETTING: The study was carried out in the audiology clinic of an otolaryngology department at a university hospital. PATIENTS: The subjects consisted of nine consecutively selected habitual Digisonic DX1OR multichannel CI users. Seven patients were postlinguistically deafened adult patients; two were congenitally deaf children. MAIN OUTCOME MEASURES: Ipsilateral recordings were performed using a previously published method. Morphology, latency, and amplitude measures of the EABR recordings were described, computed, and compared with the literature data for EABRs obtained while activating other types of CI and for acoustically evoked ABRs. Correlations between EABRs and behavioral perception thresholds were analyzed using the parametric Pearson's correlation test. RESULTS: EABRs allowed the authors to detect failure of no. 10 electrode integrity in one child. Perceptual threshold measures were found to be highly significantly related to the EABR threshold across subjects and electrode position (n = 31, r = 0.98; P < 0.001; linear regression equation: perceptual threshold = 1.06 EABR threshold + 0.76). The latencies and amplitudes were found to be similar to those described in the literature. CONCLUSIONS: EABRs may be used to estimate settings for the Digisonic DX10 CI even in a pediatric population, although they cannot entirely replace behavioral measurements, especially in children. The EABR can be employed for electrode dysfunction diagnosis. Further studies are needed to determine whether recordings of EABR quality could contribute to the evaluation of functional prognosis during the rehabilitation.

Adult↗
PubMed1998

[Oto-neuro-surgical approach and accessibility to the cochlear nuclei. Significance in auditory brain stem implant].

The auditory brainstem implant (ABI) is now used to stimulate the cochlear nucleus to obtain auditory perception in patients with type 2 neurofibromatosis. Only electrical stimulation of the cochlear nucleus complex, in the lateral recess of the fourth ventricle, can achieve auditory rehabilitation of these profound bilateral retrocochlear deafness. With 20 standard translabyrinthine approaches, our personal anatomical study propose to describe surgical landmarks of the cochlear nuclear complex and surgical accessibility of the lateral recess of the fourth ventricle. The root of vestibulocochlear nerve, the glossopharyngeal nerve and the choroid plexus of the fourth ventricle might have surgical significance because of their reliability.

Brain Stem↗
PubMed1998

[Language comprehension by children with profound congenital deafness after cochlear implant].

The consequences of profound deafness on oral language development in children are drastic and well-known. Modern multichannel cochlear implant (CI) has been proven to enhance speech production skills in prelingually deaf children. Speech production skills, however, are known not to be a reliable reflection of oral language competence as a whole. Language is an acquired common code in a specific group, enabling exchange of ideas, feelings and knowledge. In humans, speech is one of the channels conveying language. Assessing language development in CI children is more difficult than simply assessing speech production skills. Many factors may contribute to a poor or an excellent outcome, making it difficult to compare groups of children wearing or not wearing CI. The present study compared receptive language levels in paired matched children from CI and non-CI groups. The main conclusion of this study is that language comprehension scores grow significantly higher over time post-surgery in CI than in paired-matched non-CI children, despite better initial pure tone audiometric thresholds of the latter.

Audiometry, Pure-Tone↗
PubMed1997

Auditory cortex activation in deaf subjects during cochlear electrical stimulation. Evaluation by functional magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The authors detect activation in the auditory cortex during cochlear electrical stimulation in deaf patients using functional magnetic resonance (MR) imaging. METHODS: Stimulating electrode was inserted gently under local anesthesia close to the round window membrane of the cochlea in seven cochlear implant candidates. These patients suffered from postlingual-acquired deafness. Four patients were stimulated above the electrical perception threshold and three below the electrical discomfort threshold. Functional scans (fast low-angle shot 91 mseconds/60 mseconds) were acquired in an oblique axial plane running parallel to the sylvian fissure. Four consecutive series of six images were obtained in 6 minutes. The acquisition time of each image was 15 seconds. RESULTS: During electrical cochlear stimulation below the discomfort threshold, the three patients described "auditory" sensations with activation of the superior temporal regions. In two patients with electrical stimulation of the left ear, the maximum signal intensity increased by 8.42% in the right auditory cortex and 5.69% in the left. In one patient with a right electrical stimulation only the left cortex was activated. Electrical cochlear stimulation above the perception threshold induces no significant activation in the auditory cortex. CONCLUSION: Functioning MR imaging can detect activation in the auditory cortex during cochlear electrical stimulation in deaf patients using a conventional 1.5-tesla system in a routine hospital environment. Further studies are needed to investigate its usefulness in clinical practice.

Adult↗
PubMed1997

EABRs and surface potentials with a transcutaneous multielectrode cochlear implant.

In a previous study, the authors described a technique for recording ipsilateral EABRs using the DIGISONIC MXM cochlear implant (Gallégo et al, Acta Otolaryngol (Stockh) 1996; 116: 228-33) and showed that the EABR input/output functions were very similar across electrodes. In the present study a test of electrode functioning based on the recording of surface potentials is presented. Then, for each electrode the relationship between EABR thresholds and hearing thresholds was determined. Lastly, the relationship between EABR parameters and patients' performances was studied. The results show that the functioning of each implanted electrode can be assessed quickly, accurately and objectively. Furthermore it is demonstrated that a strong correlation between EABR and hearing threshold can be obtained using an automatic EABR wave detection technique. Finally it is shown that EABR inter-peak intervals are related to patient performance. These results are of the utmost importance for cochlear implant setting in children as they indicate a method of objective assessment of the functioning of each electrode and of the corresponding hearing threshold.

Adolescent↗
PubMed1997

[Value of auditory evoked potentials of the brain stem in patients with a Digisonic cochlear implant].

We report our techniques of electrically elicited Auditory Brainstem Responses (eABR) in Digisonic DX 10 cochlear implanted patients and summarize the theoretical interests of objectives measures in pre-, per- and post-operative periods of the cochlear implantation process. This report demonstrates the major interest of eABR during rehabilitation with a cochlear implant. EABR allowed us to detect the lack of device integrity in one electrode in one patient. The quality of electrically elicited responses can contribute to appreciate the electrophysiological responses during electrical stimulation. We found a very strong correlation between the objective thresholds (obtained by means of eABR) and subjective ones (obtained by means of behavioral methods); this is of major interest in the pediatric populations.

Acoustic Stimulation↗
PubMed1996

Ipsilateral ABR with cochlear implant.

Ipsilateral ABR recording technique was developed with the MXM DIGISONIC DX10 cochlear implant, involving, firstly, setting of recording variables with regard to implant and ABR constraints, and, secondly, enhancement of recording quality by signal processing. The resulting recording quality then enabled us to characterize ABR latency, amplitude and wave reproductibility according to stimulus intensity and stimulation site (electrode stimulated). The findings agree with those of the literature on contralateral human and ipsilateral animal studies. Waves III and V amplitude increased with stimulus intensity. Waves III and V latency was insensitive to stimulus intensity or site. ABR quality diminished basally.

Cochlear Implants↗
PubMed1996

A new stimulation strategy for recording electrical auditory evoked potentials in cochlear implant patients.

Recording electrical auditory brainstem responses (EABR) provides clinical insight about responses of the residual post-cochlear neural system to electrical stimulation in profoundly deaf patients. A new strategy is presented for stimulating patients already implanted with a 15-electrode cochlear implant. Since the device is fully re-programmable via a RS-232 PC interface, it was possible to load a specific stimulating strategy designed to improve the spatial locus and the temporal structure of the impulse stimulation. Waves III to V emerge more clearly when this method is applied.

Adult↗
PubMed1995

Auditory cortex activity changes in long-term sensorineural deprivation during crude cochlear electrical stimulation: evaluation by positron emission tomography.

We studied three right-handed human volunteers who have been prelingually deaf for 16 to 26 years. We measured cerebral regional activity (rA) using 15O labelled water and positron emission tomography (PET) during rest and during electrical cochlear stimulation of the right ear. The stimulus consisted of crude constant current squared pulses, it is currently employed in cochlear implant screening. Two subjects described a subjective auditory sensation under cochlear stimulation, the third did not. An increment of the rA (which is linked to the regional cerebral blood flow) in the auditory cortex was observed in all subjects, activation was ipsilateral to stimulation in one subject and contralateral in two subjects. These findings suggest 1) that auditory pathways to the cortex can remain functional a long time after prelinguistic auditory deprivation, 2) that the auditory cortex can be activated by a crude electrical stimulation of the cochlea in the absence of perception of the auditory stimulus, 3) that PET does not seem to offer any advantage for screening patients who have been prelingually deaf for a long time.

Adult↗
PubMed1995

Effectiveness of musculus palatopharyngeus resection in uvulopalatopharyngoplasty for snoring.

Sixty-eight patients with annoying snoring were included in a prospective randomized control study. Thirty-two (group 1) were subjected to classical uvulopalatopharyngoplasty (UPPP) technique; 36 (group 2) underwent a modified "extended UPPP technique" comprising the bilateral resection of the palatopharyngeal muscles. All patients were free of obstructive sleep apnea syndrome (OSAS) as documented by an overnight polysomnography. The two groups were homogeneous for age, preoperative and postoperative body mass index, and duration of follow-up. We recorded the subjective preoperative and postoperative symptoms as evaluated by the patient and the bed partner, and the immediate postoperative complaints. The only statistically significant difference between the two groups was pain. Thus, in this series, the "extended UPPP technique" showed no better results in the surgical approach to snoring, and its morbidity rate is higher.

Adult↗
PubMed1995

Analytic importance of the coding features for the discrimination of vowels in the cochlear implant signal.

The present study considers the analytic importance of the excitation pulse features delivered by a Nucleus cochlear implant using the F0F1F2 strategy. Four cochlear implant patients and 10 speakers uttering two 48-item lists constructed from four basic French vowels participated in this study. Patterns were presented to the patients and played at the input of an acquisition system in order to record the pulse features. Confusion matrices obtained with the patients and with automatic recognition procedures were then compared in order to find out the best-matching models simulating the patients' performances, out of 255 possibilities. The automatic recognition was carried out according to fuzzy logic based on the elementary features of the pulses coding the vowels. Results show that the essential features strongly depended on the subject.

Adult↗
PubMed1995

Chronic tympanic membrane perforation: an animal model.

Acute perforations in the tympanic membranes (TM) of animals are not good models for assessment of materials used as graft membranes or of substances with the potential to activate tympanic membrane healing mechanisms for closing perforations. Most acute TM perforations heal spontaneously, in both animals and humans. Acute TM perforation models are not analogous to the pathologic human problem of long-standing TM perforation. Bilateral subtotal symmetric perforations, with each animal serving as its own control provide a suitable model. Fourteen dogs were operated. Subtotal perforation of TM in right ears were soaked with 2% glutaraldehyde to develop an animal model for persistent tympanic membrane perforation. Subtotal myringectomy was performed on left ears, without chemical treatment of the rim. Perforations were standardized in size. The healing pattern was evaluated weekly for a 15-week period. Six of the right ears and 14 of the left ears completely healed within 15 weeks. Statistically, the mean delay of closure was higher in the treated group than in the non-treated group, and the two groups were different according the closure rate criterion. Histologic analyses of persistent TM perforations and of healed cases were performed.

Animals↗