Biomedical subjects

F E Offeciers

Publications and source records attributed to F E Offeciers.

At least 19 recordsLinked to original sources

PubMed2003

Design, construction and mechanical optimisation process of electrode with radial current flow in the scala tympani.

A 48 contact cochlear implant electrode has been constructed for electrical stimulation of the auditory nerve. The stimulating contacts of this electrode are organised in two layers: 31 contacts on the upper surface directed towards the habenula perforata and 17 contacts connected together as one longitudinal contact on the underside. The design of the electrode carrier aims to make radial current flow possible in the cochlea. The mechanical structure of the newly designed electrode was optimised to obtain maximal insertion depth. Electrode insertion tests were performed in a transparent acrylic model of the human cochlea.

Biomedical Engineering↗

PubMed2003

Results of 100 vestibular schwannoma operations.

Between 1991 and 2000, 154 cerebello-pontine angle (CPA) tumors were seen at the University ENT-department of the Sint-Augustinus Hospital, Antwerp. Amongst these, 127 were vestibular schwannomas detected by MR-imaging. Noteworthy is that in 5% of these, the ABR latencies were within normal limits. One hundred patients underwent tumor removal either by the translabyrinthine (66) or by the retrosigmoid (34) approach and all had a follow-up of at least two years. For large tumors (> 2 cm extension in the CPA) or in the case of poor hearing the translabyrinthine approach was used. For patients with tumor extension in the CPA ofless than 2 cm and with serviceable residual hearing on the affected side, (at least < 50 dB PTA, > 50% SSD) the retrosigmoid approach with endoscopic control was used. Most patients (96%) had a House-Brackmann grade 1 or 2 facial function before surgery. Although this group dropped to 76% 6 months after surgery it increased again to reach 84% within 2 years. Thus, 88% percent of patients with normal preoperative facial function achieved a Grade I or II after two years. The facial outcome is very much dependent on the size of the tumor. A good result (House-Brackmann Grade 1 or 2) is the rule (92%) for small tumors (< 10 mm extension in the CPA), still attainable (82%) for medium tumors (11-25 mm), but less apparent (56%) for large tumors (> 26 mm). It was possible to preserve hearing in 38% of the retrosigmoid interventions. Although unbalance and headache are rather frequent early postoperative symptoms (respectively 52% and 31%), these complaints decrease with time and are infrequent after two years (unbalance = 7%, headache = 4%). Our results were compared with three large multicentric studies. They are in line with data from the literature and compare favorably with the better results. Although good grading systems exist for facial nerve and hearing outcomes, the authors regret that a general consensus on tumor size measurement is still not yet available. It would facilitate data comparison between different centers and the choice between the therapeutical modalities.

Ear, Inner↗

PubMed2002

Otosclerosis: a genetically heterogeneous disease involving at least three different genes.

Otosclerosis is caused by abnormal bone homeostasis of the otic capsule, resulting in hearing impairment in 0.3%-0.4% of the white population. The etiology of the disease remains unclear and environmental as well as genetic factors have been implicated. We localized the first autosomal-dominant locus to chromosome 15 in 1998 (OTSC1) in an Indian family and, recently, we reported the localization of a second gene for otosclerosis to a 16 cM interval on chromosome 7q (OTSC2). In this study, we recruited and analyzed nine additional families (seven Belgian and two Dutch families with 53 affected and 20 unaffected subjects) to investigate the importance of these loci in autosomal-dominant otosclerosis. We completed linkage analysis with three microsatellite markers of chromosome 15 (D15S652, D15S1004, D15S657) and five microsatellite markers of chromosome 7 (D7S495, D7S2560, D7S684, D7S2513, D7S2426). In two families, results compatible with linkage to OTSC2 were found, but in the seven remaining families OTSC1 and OTSC2 were excluded. Heterogeneity testing provided significant evidence for genetic heterogeneity, with an estimated 25% of families linked to OTSC2. These results indicate that, besides OTSC1 and OTSC2, there must be at least one additional otosclerosis locus.

Chromosomes, Human, Pair 15↗

PubMed2002

Middle ear status in ears showing high admittance tympanograms. Clinical value of the use of the two-component 678 Hz oto-admittance tympanogram.

The present paper reports on the results of a retrospective study using 678 Hz susceptance-conductance tympanometry performed on abnormally high admittant middle ears. High admittance was proven to be caused by (partial) disruption or lysis of the ossicular chain. Retrospective analysis shows that 678 Hz tympanometry seems to be more accurate in the differential diagnosis of ossicular chain disruptions compared to CT-imaging of the ossicular chain (88% versus 81% correct identification respectively). Classic tympanometry using a probe frequency of 226 Hz was abnormal in only 43% of the cases.

Acoustic Impedance Tests↗

PubMed2001

A second gene for otosclerosis, OTSC2, maps to chromosome 7q34-36.

Otosclerosis due to abnormal bone homeostasis of the otic capsule is a frequent cause of hearing loss in adults. Usually, the hearing loss is conductive, resulting from fixation of the stapedial footplate, which prevents normal ossicular vibration in response to sound. An additional type of sensorineural hearing loss may be caused by otosclerotic damage to the cochlea. The etiology of the disease is unknown, and both environmental and genetic factors have been implicated. Autosomal dominant inheritance with reduced penetrance has been proposed, but large families are extremely rare. To elucidate the pathogenesis of the disease, identification of the responsible genes is essential. In this study, we completed linkage analysis in a Belgian family in which otosclerosis segregates as an autosomal dominant disease. After excluding linkage to a known locus on chromosome 15 (OTSC1), we found linkage on chromosome 7q, with a multipoint LOD score of 3.54. Analysis of key recombinant individuals maps this otosclerosis locus (OTSC2) to a 16-cM interval on chromosome 7q34-36 between markers D7S495 and D7S2426.

Alleles↗

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

Box and whisker plots for graphic presentation of audiometric results of conductive hearing loss treatment.

The Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery has published guidelines for the reporting of audiometric results of middle ear interventions. It recommends the reporting of several audiometric variables by means of two summary parameters: means and standard deviation. This article advocates the use of other summary statistics, namely the median, quartiles, and extremes, because they do not require a normal distribution of the audiometric data and they are not sensitive to variations of the extreme values. On the basis of the exploratory data analysis, we propose a graphic method to present the Committee's variables in terms of their summary statistics. This "multiple box and whisker plot" offers a detailed and accurate overview of six variables in one graph.

Audiometry↗

PubMed1998

Mutations in the human alpha-tectorin gene cause autosomal dominant non-syndromic hearing impairment.

The tectorial membrane is an extracellular matrix of the inner ear that contacts the stereocilia bundles of specialized sensory hair cells. Sound induces movement of these hair cells relative to the tectorial membrane, deflects the stereocilia, and leads to fluctuations in hair-cell membrane potential, transducing sound into electrical signals. Alpha-tectorin is one of the major non-collagenous components of the tectorial membrane. Recently, the gene encoding mouse alpha-tectorin (Tecta) was mapped to a region of mouse chromosome 9, which shows evolutionary conservation with human chromosome 11q (ref. 3), where linkage was found in two families, one Belgian (DFNA12; ref. 4) and the other, Austrian (DFNA8; unpublished data), with autosomal dominant non-syndromic hearing impairment. We determined the complete sequence and the intron-exon structure of the human TECTA gene. In both families, mutation analysis revealed missense mutations which replace conserved amino-acid residues within the zona pellucida domain of TECTA. These findings indicate that mutations in TECTA are responsible for hearing impairment in these families, and implicate a new type of protein in the pathogenesis of hearing impairment.

Alternative Splicing↗

PubMed1998

Use of antibiotic prophylaxis in ear surgery.

A prospective, double-blind, randomized, placebo-controlled study was performed to evaluate the effect of antibiotic prophylaxis in ear surgery. The present study reports on the results of 750 patients, half of whom received cefuroxime for 1 day, the other half, placebo. All postoperative infections occurring within 2 weeks after the intervention were recorded, together with several preoperative and perioperative parameters. It is concluded that exploratory tympanoplasties (including stapedotomy) and "dry perforation" tympanoplasties should be considered "clean" operations according to the American National Research Council and do not benefit from antibiotic prophylaxis. On the other hand, tympanoplasties performed on draining ears and on ears with cholesteatoma should be considered "dirty" operations for which antibiotic prophylaxis may decrease the postoperative infection rate by factor 3. All postoperative infections healed without sequels under proper treatment, except for three that resulted in graft necrosis--one in the placebo group and two in the cefuroxime group. In consequence, prophylaxis may not be mandatory in the dirty group, although the authors advocate its use for the sake of patient and surgeon comfort.

Antibiotic Prophylaxis↗

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

Tympano-ossicular allografts and HIV transmission.

OBJECTIVE: To evaluate the potential risk of human immunodeficiency virus (HIV) transmission by tympano-ossicular allografts by studying the efficacy of standard preservation techniques to eliminate the presence of proviral HIV-1 DNA fragments in contaminated ossicles. STUDY DESIGN: Randomized single-blind prospective study on the ossicles of HIV-1 patients. MATERIAL: Ossicles of five patients who had died of acquired immune deficiency syndrome (AIDS) (HIV-1 infection) were taken within 6 hours postmortem and allocated randomly to a treatment and nontreatment group. Liver and skin biopsies were taken as positive control specimens. PROCESSING: The treatment group was processed with standard techniques (formaldehyde) for tympano-ossicular allograft preservation and the nontreatment group was only washed, dried, and stored in sterile tubes at -700 degrees without further processing. MAIN OUTCOME MEASURE: Proviral HIV-1 DNA was detected using polymerase chain reaction amplification techniques. RESULTS: No proviral HIV-1 DNA was detected in any of the treated ossicles, whereas three of five sets of untreated ossicles were positive. The positive control specimens of all treated and nontreated sets were positive for proviral HIV-1 DNA. CONCLUSIONS: These results suggest that the preservation technique for tympano-ossicular allografts is safe with regard to HIV-1 transmission.

DNA, Viral↗

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↗

PubMed1998

Total auricular repair: bone anchored prosthesis or plastic reconstruction?

Major breakthroughs in implantology and prosthetic materials, but also in reconstructive surgery of the auricle, have opened new possibilities in the rehabilitation of patients with an absent auricle. The management of such cases and the surgical results in 62 cases are presented. Thirty-five bone-anchored prostheses have been adapted and 27 total auricular reconstructions performed. As long as the conditions of osseo-integration are respected, surgery for an epithesis is easy and comprises no major risks. The side effects of the percutaneous connection (mainly skin reactions) are often minor. All patients are satisfied with their prosthesis and wear it all day long. For the total auricular repair, mainly in major congenital malformations, two techniques were adopted: first the Brent technique followed by the Nagata technique, preferred nowadays. The Brent technique was found safe with good results, but the modification by NAGATA offered two additional advantages: a reduction of the operative stages from 4 to 2 and a better definition of the auricular reliefs by the more elaborate fabrication of the framework. With increasing experience the results of the total auricular reconstructions improved significantly and became more predictable. Also the advantages and disadvantages of both (the reconstructive and prosthetic) approaches are discussed.

Adult↗

PubMed1997

Tympano-ossicular allografts for cholesteatoma in children.

At the Sint Augustinus Hospital, Antwerp, Belgium, all children with cholesteatoma are operated by a canal wall up approach and immediate reconstruction with a tympano-ossicular allograft. In the majority of the cases, a second stage is performed after 1 year. This paper presents the results of a retrospective review of the charts of 103 consecutive children treated between 1979 and 1995. The mean patient age was 10 years and the mean postoperative follow-up was 4.5 years. In 28 children residual cholesteatoma was found at the second stage operation and 20 developed recurrent cholesteatoma in the course of time. So far no residual cholesteatoma surfaced after the staged procedure, but 11 children needed more than two operations to control recurrent disease. An intact, trouble-free graft was present in 79 children at the latest follow-up. The median postoperative bone-conduction thresholds were equal to the preoperative thresholds. The median postoperative air-conduction thresholds improved in 50% of the cases, remained unchanged in 25%, and deteriorated in 25% of the cases. It is concluded that the tympano-ossicular allograft technique is effective and safe and offers good anatomical and acceptable functional results.

Adolescent↗

PubMed1997

Histology of the perforated tympanic membrane and its muco-epithelial junction.

A histological study was performed on total human tympanic membranes with a central perforation. The specimens originated from 30 consecutive and unselected operations in which a total myringectomy was performed prior to reconstruction by means of a tympanic allograft. Beside excessive thickening of the tympanic membrane in 73%, all membranes showed other histological abnormalities: inflammation (97%), excessive fibrosis (97%), tympanosclerosis (80%), hyperkeratosis (83%), rete riges (43%) and epithelial inclusions (6%). Histological localisation of the muco-epithelial junction showed a medial position in 30%, with extensive middle ear invasion by squamous epithelium in 7%. The surgeon performing myringoplasty should keep these findings in mind and he should closely examine the medial side of the perforated tympanic membrane in order to remove any ingrowing epithelium that otherwise would be trapped.

Adolescent↗

PubMed1997

Aplasia and hypoplasia of the vestibulocochlear nerve: diagnosis with MR imaging.

PURPOSE: To introduce aplasia or hypoplasia of the vestibulocochlear nerve (VCN) as a possible cause of hearing loss and to identify the magnetic resonance (MR) imaging characteristics of this entity. MATERIALS AND METHODS: In seven patients with congenital deafness or unexplained sensorineural hearing loss, MR imaging enabled diagnosis of aplasia or hypoplasia of the VCN. Axial (0.7-mm) three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) images and parasagittal reconstruction images perpendicular on the course of the VCN were obtained. Twenty normal inner ears were also studied; their findings were compared with those of the patients. RESULTS: The facial nerve and inferior and superior vestibular and cochlear branches of the VCN were identified on the MR images in the 20 normal inner ears. Aplasia of the VCN was detected in two patients with normal labyrinths but with a severe stenosis of the internal auditory canal. A common VCN with absence of the cochlear branch was found bilaterally in two patients with a congenital malformation of the labyrinth. A common VCN with absence or hypoplasia of the cochlear branch was found in three patients with normal internal auditory canals and labyrinths. CONCLUSION: Submillimetric gradient-echo images (eg, 3DFT-CISS) should always be used to exclude aplasia or hypoplasia of the cochlear branch of the VCN in all cochlear implant candidates and patients with congenital deafness. This entity, which can occur with or without associated labyrinthine malformation, should be confirmed in two planes.

Adult↗