Biomedical subjects

T Somers

Publications and source records attributed to T Somers.

At least 19 recordsLinked to original sources

PubMed2006

Single-shot, turbo spin-echo, diffusion-weighted imaging versus spin-echo-planar, diffusion-weighted imaging in the detection of acquired middle ear cholesteatoma.

Diagnosis of acquired middle ear cholesteatoma on MR imaging is mostly done on late postgadolinium T1-weighted MR images and/or echo-planar (EPI) diffusion-weighted (DWI) MR images. We describe the appearance of a case of a complicated attical middle ear cholesteatoma on single-shot (SS) turbo spin-echo (TSE) DWI compared with EPI-DWI. This case suggests a higher reliability of SS TSE-DWI in the diagnosis of acquired middle ear cholesteatoma.

Aged↗

PubMed2004

Allograft tympanoplasty.

Tympano-ossicular allografts are human transplants of the tympanic membrane alone or with the ossicles included. The authors review its use in their department since the introduction of the technique 40 years ago by J. Marquet. The advantages of the technique (near normal anatomical and physiological reconstruction) are discussed, as well as its disadvantages (time consuming harvesting, risk of disease transmission). Some technical modifications for specific indications have been adapted in our department and are described in detail. The authors believe that the tympano-ossicular allograft is the material of choice in extensively diseased middle ears destroyed by chronic otitis media with or without cholesteatoma.

Cholesteatoma, Middle Ear↗

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↗

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

CT and MR imaging of congential abnormalities of the inner ear and internal auditory canal.

The embryology of the inner ear must be known as many of the inner ear malformations present as a result of the arrest during the various stages of embryology. These malformations are described in this "embryologic" perspective and specific names for certain malformations are no longer used. Both CT and MR can be used to look at inner ear malformations but often both techniques are complementary. However, CT is preferred when associated middle- or external ear malformations must be excluded. Magnetic resonance is preferred when subtle changes in the membranous labyrinth or abnormalities of the nerves in the internal auditory canal must be visualised. The CT and MR technique must however be adapted as more and more subtle congenital malformations can only be seen when the right technique is used. The heavily T2-weighted gradient-echo or fast spin-echo MR techniques are mandatory if malformations of the inner ear must be excluded. The purpose of this paper is to describe the techniques used to study these patients and to give an overview of the most frequent and important congenital malformations which can be found in the inner ear and internal auditory canal/cerebellopontine angle.

Ear, Inner↗

PubMed2001

Prognostic value of magnetic resonance imaging findings in hearing preservation surgery for vestibular schwannoma.

OBJECTIVE: The purpose of this study was to determine whether three magnetic resonance imaging (MRI) findings (tumor size, extension to the fundus, intralabyrinthine signal intensity) have a predictive value to hearing preservation in vestibular schwannoma surgery. STUDY DESIGN: A retrospective study was conducted of preoperative high-resolution MR images in a series of consecutive hearing preservation attempts for vestibular schwannomas. PATIENTS: Twenty-six consecutive records of patients with an acoustic tumor removed via a retrosigmoid transcanal approach were analyzed, and the MR images were reviewed blindly and compared with postoperative hearing. SETTING: The study took place in a tertiary referral center. Imaging Techniques: The MR sequences used in this study were unenhanced and gadolinium-enhanced T1-weighted spin-echo images and gradient echo images (3DFT-CISS). MAIN OUTCOME MEASURES: The predictive value of three MRI signs was analyzed: tumor size, lateral extension of the tumor (with and without obliteration of the fundus), and the maintenance of, or decrease in, the intralabyrinthine signal intensity on the affected side in comparison with the signal intensity on the opposite normal side as seen on 3DFT-CISS images. RESULTS: The tumor size in ears in which hearing was preserved averaged 15 mm and was 17 mm in those cases where hearing was not preserved. Hearing was preserved in 50% of ears when the tumor did not extend to the fundus but in only 33% when the fundus was obliterated by tumor. A "normal" intralabyrinthine signal on CISS images (being an isointense signal when compared with the contralateral unaffected ear) was followed by hearing preservation in 82% of ears, whereas in cases where the intralabyrinthine signal was low, hearing was preserved in only 20%. This correlation was statistically significant (p < 0.05). CONCLUSION: The intralabyrinthine signal intensity on 3DFT-CISS gradient-echo images is a valuable additional tool for determining candidacy for hearing preservation surgery. In two cases with preoperative decrease in signal intensity of the intralabyrinthine fluids, control MRI after surgery showed spontaneous recovery of normal intralabyrinthine signal intensity. The authors hypothesize that vascular compression in the internal auditory canal by the tumor is responsible for the observed intralabyrinthine signal decrease.

Adult↗

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↗

PubMed2001

Giant congenital intracranial epidermoid tumor: a case report.

A case of a large epidermoid tumor in a middle-aged woman with limited symptomatology is reported. Intracranial epidermoid tumors are slow growing and benign lesions. Although the treatment of choice consists in complete resection, partial removal may be preferred in some very extended cases presenting with minimal symptomatology because of the lower morbidity involved. This case illustrates a key-hole approach via a retrolabyrinthine route with preservation of all labyrinthine structures, including the endolymphatic sac and duct. The epidermoid was partially removed by extensive intracapsular debulking under endoscopic control with the aim of decreasing cerebral compression. All cranial nerve functions were preserved and the 6 month postoperative imaging has remained unchanged over a 2-year long follow-up period. The literature regarding this rare pathology is also reviewed.

Adult↗

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↗

PubMed1999

Large intrapetrous facial schwannoma presenting as a glomus tumor.

A 45 y old man suffered since a long time from right-sided hearing loss, tinnitus and, very recently, facial palsy. CT-scanning and MRI showed a very large intrapetrous lesion centered on the jugular foramen suggestive for a glomus tumor. During surgery a facial schwannoma was disclosed. The management and therapy of this lesion is discussed.

Diagnosis, Differential↗

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

Growth factors in tympanic membrane perforations.

OBJECTIVE: Little is known about the arrested healing of chronic central tympanic membrane perforations and the mechanism involved in this process. Some authors have traced the failure to a growth factor deficiency at the perforation margin. In addition, recently, several growth factors have been tried out to improve tympanic membrane (TM) closure in animals. The authors sought to determine the expression of some well-known growth factor peptides in normal human TM and in TMs with a chronic central perforation. MATERIALS AND METHODS: Total TM specimens were obtained from patients with a normal TM (N = 10) soon after death and from patients with a chronic perforation (N = 20) undergoing myringoplasty with use of an allograft TM. Formaldehyde solution-fixed TMs were analyzed after immunohistochemical staining using highly purified monoclonal antibodies to determine whether epidermal growth factor receptor (EGF-r), transforming growth factor-alpha (TGF-alpha), basic fibroblast growth factor (b-FGF), or transforming growth factor-beta 1 (TGF-beta 1) was expressed in the TMs. RESULTS: The distribution pattern for EGF-r, TGF-alpha, and b-FGF was similar in perforated and nonperforated TMs. In contrast to this, TGF-beta 1 staining was markedly different in perforated and nonperforated TMs. No or minimal TGF-beta 1 was observed in normal TMs, whereas TGF-beta 1 staining was prominent in perforated membranes, mostly at the perforation border. CONCLUSIONS: The authors experimental findings imply that EGF-r, b-FGF, and TGF-alpha expression are not significantly different in TMs with and without a central chronic perforation. However, for TGF-beta 1, the authors found an increased staining pattern in perforated TMs when compared with that of normal TMs, and staining at the fibrotic and scarred perforation margin was pronounced. Based on these findings, the authors speculate on the possible role of TGF-beta 1 in the development of the fibrotic scar at the perforation margin explaining the deficient healing pattern of tympanic membranes in chronic otitis media. Possible clinical implications for the future, including growth factor therapy, are discussed.

Antibodies, Monoclonal↗

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↗