Biomedical subjects

K Daemers

Publications and source records attributed to K Daemers.

12 recordsLinked to original sources

PubMed2004

Basic fitting and evaluation parameters of a newly designed cochlear implant electrode.

OBJECTIVE: To validate a newly designed cochlear implant electrode (TRACE) in the standard monopolar mode and compare it to a patient group implanted with a standard Nucleus Contour cochlear implant electrode. The electrode contacts of the TRACE electrode have the same active surface area for stimulation, but the position in the scala tympani is different from that of the Nucleus Contour electrode. MATERIAL AND METHODS: The following parameters, used in cochlear implant fitting and evaluation procedures, were determined: the threshold and comfort stimulation current levels; the electrode impedances; and the phoneme discrimination and speech recognition scores using the ACE speech algorithm. CONCLUSION: The new electrode does not differ significantly from the standard Nucleus Contour electrode in terms of the investigated parameters within the test group.

Acoustic Impedance Tests↗

PubMed2003

Cochlear implants in aplasia and hypoplasia of the cochleovestibular nerve.

OBJECTIVE: To report on the outcome of four patients with aplasia or hypoplasia of the cochleovestibular nerve who have received a cochlear implant. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Four patients with: 1) type I aplasia; 2) type IIa aplasia; 3) type IIa hypoplasia; and 4) type IIb aplasia received a cochlear implant. All patients had corner audiograms even with hearing aids. INTERVENTION: Three patients received a LAURA multichannel implant, and one patient received a Nucleus 24 implant. MAIN OUTCOME MEASURE: Auditory performance, educational setting. RESULTS: The patients with type I and type IIb aplasia did not have auditive perception with their implant and became non-users. Both are now in a total communication educational setting. The patients with type IIa aplasia and hypoplasia had moderate audiological results with the implant with audiometrical thresholds of approximately 40-60 dB HL (pure tone average), moderate phoneme discrimination, and poor word discrimination. One child is in a total communication educational setting and the other in an oral educational setting, but the preferred mode of communication remains total communication for both. Both appear to benefit from the implant nonetheless. CONCLUSION: Patients with aplasia/hypoplasia of the cochleovestibular nerve should be counseled with caution with respect to cochlear implantation, but particular circumstances may justify the intervention. At present these circumstances seem to be a type IIa aplasia or hypoplasia in which the end organ (cochlea or common cavity) still connects to a neural structure on MRI.

Auditory Perception↗

PubMed2001

Neonatal hearing screening with transient evoked otoacoustic emissions--retrospective analysis on performance parameters.

The present paper reports on the implementation of a maternity based neonatal hearing-screening program in a private hospital. A retrospective analysis is performed on the test pass rate, the coverage and the number of children that become lost to follow-up. The data show a steady learning curve with a time course of several years. In the current screening practice, the test pass rate is at 99.0%, the coverage is at 96% (birth rate of 2000 per annum) and almost no babies get lost to follow-up.

Follow-Up Studies↗

PubMed2001

Contralateral suppression of transient evoked otoacoustic emissions: normative data for a clinical test set-up.

HYPOTHESIS: Contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) can be used in a clinical set-up using a procedure based on a unique and robust parameter to quantify the magnitude of suppression for a subject. BACKGROUND: TEOAEs can be suppressed by delivering contralateral white noise (WN). This suppression is thought to be mediated via the efferent nerve fibers that innervate the outer hair cells. The ipsilateral TEOAE-eliciting click stimulus level and the contralateral WN level have a strong impact on the recorded level of suppression. METHODS: TEOAEs were recorded using the nonlinear stimulation mode in two conditions (with and without contralateral WN). An optimal TEOAE-eliciting click stimulus level and contralateral WN level were defined to obtain a unique and robust parameter to quantify the magnitude of suppression. RESULTS: Suppression of TEOAEs with contralateral WN can be measured in a clinical set-up using nonlinear stimulation, and the level of suppression is of the same order of magnitude as measures using the linear stimulation recording mode. The level of suppression appears to be "locked" to the interaural difference between ipsilateral TEOAE-eliciting broadband click stimulus level and the contralateral WN level. CONCLUSIONS: A procedure is proposed to record contralateral suppression in a clinical set-up, and normative data are given for a normal-hearing population (n = 60).

Adolescent↗

PubMed2001

A Two-stage bipodal screening model for universal neonatal hearing screening.

OBJECTIVE: A model is proposed for universal neonatal hearing screening. METHODS: The screening model is two-staged because it consists of a first test and, in case of failure (1.4% of the subjects), of a retest 3 weeks later. It is bipodal because it involves both the hospital audiologic department and a central Well Baby Organization. The idea is to have a maximal number of newborns tested at the maternity by trained audiologists and to have the Well Baby Organization trace and chase the missing subjects. The model has been evaluated during 1 calendar year (1999) in a maternity with 2,012 newborns. RESULT: The result is a coverage of 99.3%. Most newborns (97.3%) were tested at the maternity ward with a total time investment of less than 15 minutes per child. The actual test time is 2 minutes, 12 seconds (median value). The Well Baby Organization keeps track of all the results and has to test no more than 2% of the newborns. Sensitivity and specificity were not the primary outcomes of this evaluation, but they were similar to those of a previous study evaluating the screen procedure on a larger scale, giving a sensitivity of approximately 100% and a false alarm rate of 1/1,000. CONCLUSION: These figures demonstrate that universal neonatal hearing screening is feasible within the existing health care structure, with unprecedented coverage, sensitivity, and specificity.

Belgium↗

PubMed1999

Audiological findings in large vestibular aqueduct syndrome.

An enlarged vestibular aqueduct is a congenital disorder causing early onset and progressive hearing loss in children. This paper presents the audiological findings at first presentation and the audiological evolution in 10 consecutive cases presenting with hearing loss and showing a large vestibular aqueduct on imaging. The reported onset of the hearing loss is within the first few years of life. Most of the cases (80%) showed bilateral involvement. The sex ratio was 1. Patients presented on average at age 5 with a median hearing loss of 62 dB at the speech frequencies. The hearing loss was essentially asymmetrical with an interaural difference, of 33 dB and it was a mixed type of hearing loss in 90% of the cases. The authors claim that the conductive component of this hearing loss is a pure cochlear conductive loss which may be pathognomonic for the disease. The presence of a conductive component in a child is easily misinterpreted as a middle ear ventilation problem or in case of good ventilation as an ossicular problem (type otosclerosis). In addition and in contrast to most literature data, the authors did not find evidence for stabilization of the hearing loss but they found a steady decrease of the hearing at an average rate of 4 dB/year.

Audiometry↗

PubMed1998

The LAURA Pediatric Cochlear Implant Program in Antwerp: what have we learnt in 5 years?

The LAURA Cochlear Implant Program at the University of Antwerp was initiated 5 years ago. Up to now 50 children have received the LAURA cochlear implant (Philips Hearing Implants). Our accumulated experience in selecting the patients, counselling their parents, implanting and fitting the device allowed us to gradually modify the inclusion/exclusion criteria for cochlear implantation and achieve very rewarding results. The most important change was the gradual shift towards a younger age at implantation, our youngest implantee being 11 months old. In this paper we describe the rationale for this change, as well as the prerequisites for a successful pediatric cochlear implant program.

Belgium↗

PubMed1998

A new autosomal-dominant locus (DFNA12) is responsible for a nonsyndromic, midfrequency, prelingual and nonprogressive sensorineural hearing loss.

OBJECTIVE: This study aimed to report on the audiologic findings of a nonsyndromic autosomal-dominant hearing loss of which the gene (DFNA 12) recently was found to map to chromosome 11q22-24. The study also aimed to propose and evaluate an algorithm based on the audiometric findings to discriminate between affected and unaffected family members before genetic linkage analysis. STUDY DESIGN: The study design was a retrospective analysis of the audiometric data of genetically affected and unaffected patients. SETTING: The study was conducted at a tertiary referral center. PATIENTS: A total of 17 genetically affected and 54 unaffected family members were studied. INTERVENTIONS: Pure-tone audiometry with air and bone conduction and construction and evaluation of an algorithm were performed. MAIN OUTCOME MEASURES: The type and degree of hearing loss as compared to age and gender-dependent values according to the International Organization for Standardization 7029 standard were measured. For this comparison, the variable "hearing standard deviations" (HSD) is introduced and is defined as the number of standard deviations that a hearing threshold is lying above the age and gender-related median at the given frequency. A description of the algorithm and an evaluation in terms of alpha- and beta-error also were measured. RESULTS: The hearing loss is nonsyndromic, sensorineural, moderate-to-moderately severe (pure-tone average, 51 dB at age 18 years), with an early onset (probably prelingual) and no progression. It affects all frequencies but mainly the midfrequencies (500, 1,000, and 2,000 Hz). The algorithm consists of an analysis of variance to determine the frequency that is most sensitive for the genetic trait under study and on the ranking of the family members according to their hearing loss (HSD) at this frequency. Individual persons are labeled as "affected" or "unaffected" according to this ranking.

Adolescent↗

PubMed1996

Numerical assessment of TOAE screening results: currently used criteria and their effect on TOAE prevalence figures.

The literature on neonatal hearing screening by means of oto-acoustic emissions (OAE's) presents various prevalence figures, and gives little quantitative information on the procedure used to score the recordings. If the OAE test is to be interpreted by users who do not have the opportunity to develop intuitive interpretation skills through extensive training, a clear numerical decision criterion is needed. The present paper discusses the scoring procedure used by 25 teams, which together screen 22,356 neonates annually. More than 60% of the groups involved in this study use visual interpretation of the recorded OAE response, together with numerical criteria. Amongst the teams, 21 different ways of numerical scoring are used. It is shown that for a given set of OAE recordings, prevalence varies from 61% to 90%, depending on the numerical decision criterion being applied. We conclude that at this moment no consensus exists regarding the numerical criterion to be used when assessing OAE screening results. In view of the strong effect of criteria on the outcome of OAE screening, such consensus is urgently needed, but should be based on sensitivity and specificity figures for each scoring technique.

Adult↗

PubMed1996

Neonatal hearing screening with otoacoustic emissions: an evaluation.

For several years now, it is possible to test the cochlear function immediately after birth in an easy way by means of click evoked otoacoustic emissions. Thanks to this early detection, hearing aid fitting and appropriate hearing rehabilitation can now be started at a very young age, which significantly enhances the possibility of integration of the congenitally hard of hearing in society. An international consensus is growing to endorse a universal neonatal hearing screening in western societies. Setting up screening programs necessitates good preparation, continuous quality control and regular analysis of procedures and results. The present paper evaluates the procedure as organised from January 1993 till December 1994 in the University ENT-Department of the Sint-Augustinus Hospital. Of the 907 included neonates who were considered not to be at risk for hearing loss, 81% passed the test immediately, and 93% passed after maximum 3 tests. Some changes in the initial procedure increased the prevalence of emissions from 69% to 84%. The practical problems of the screening program and especially the importance of a stringent follow-up procedure in case of failure, are discussed.

Algorithms↗

PubMed1994

The bone anchored hearing aid and auricular prosthesis.

The bone anchored hearing aid (B.A.H.A.) has been fitted to 10 of our patients presenting a bilateral profound conductive hearing loss and who were unable to wear a classical hearing aid. The group of patients with bilateral inoperable aural atresia (n = 5) formed the main indication and were found to give the best results. Cases with bilateral chronic otitis media (n = 5), presenting otorrhea each time a classical hearing aid was worn, formed the second indication. Audiometric performances are dependent on the bone conduction thresholds. The auricular epithesis has been adapted in 11 cases, mainly for atretic ears. The surgery for B.A.H.A. and epithesis is now routinely performed in one stage and has been found safe and reliable. The skin reactions around the abutments (total number fixtures = 32) were found to be rare and often easy to treat. Only around one abutment further subcutaneous tissue reduction was necessary to stabilize the skin. The B.A.H.A. and auricular epithesis are valuable alternatives in those cases where the limits of reconstructive (middle or outer ear) surgery are reached.

Adolescent↗

PubMedDate not supplied

Neonatal hearing screening with transient evoked otoacoustic emissions: a learning curve.

The present paper reports on the implementation of a neonatal hearing screening programme in a private hospital in Belgium. A maternity-based neonatal hearing screening project with transient evoked otoacoustic emissions (TEOAEs) was started in 1993. The cost of the test was not covered by the public health insurance, so the parents had to pay the full cost for screening their child (approximately 30 Euro). Since 1993 the programme strategies have been changed on several occasions to improve the quality and efficacy. A retrospective analysis was performed on: (1) the test pass rate; (2) the coverage; and (3) the number of children who become 'Lost to follow-up' after failing the initial test. The data show a steady learning curve with a time course of several years. They also demonstrate that it is worthwhile and feasible to run a high-quality screening programme in a private establishment.

Belgium↗