Biomedical subjects

Attila Torkos

Publications and source records attributed to Attila Torkos.

6 recordsLinked to original sources

PubMed2006

Flat-panel volume computed tomography for cochlear implant electrode array examination in isolated temporal bone specimens.

HYPOTHESIS: Flat-panel based volume computed tomography could improve cochlear implant electrode evaluation in comparison with multislice computed tomography. BACKGROUND: Flat-panel based volume computed tomography offers higher spatial resolution and less metal artifacts than multislice computed tomography. Both characteristics could improve the evaluation of challenging but important questions in cochlear implantation assessment, such as an exact imaging of cochlea, osseous spiral lamina, electrode array position, and single electrode contacts. These questions are not currently fully answered by multislice computed tomography. METHODS: Four isolated temporal bone specimens were scanned in a current multislice computed tomography scanner and in two experimental flat-panel based volume computed tomography scanners before and after cochlea implantation. To compare flat-panel based volume computed tomography and multislice computed tomography, four features were rated according to the following criteria: 1) visibility of the cochlea; 2) visibility of the osseous spiral lamina; 3) discernibility of individual electrode contacts; and 4) the ability to determine the electrode array position relative to scala tympani and scala vestibuli. Layer-by-layer microgrinding pictures were used as the ground truth for verification of imaging findings. RESULTS: Flat-panel based volume computed tomography was superior to multislice computed tomography in all four features rated. The cochlea and facial nerve canal were much better delineated in flat-panel based volume computed tomography. The osseous spiral lamina and single electrode contacts were only visible in flat-panel based volume computed tomography. Assessment of implant position with regard to the cochlear spaces was considerably improved by flat-panel based volume computed tomography. CONCLUSION: Cochlear implantation assessment could be improved by flat-panel based volume computed tomography and, therefore, would be highly beneficial for cochlea implantation research and for clinical evaluation. However, these first results were shown by scanning isolated temporal bone specimens; scanning whole human skull bases might be more challenging.

Artifacts↗

PubMed2005

The use of buccal smears for a non-invasive screening of the 35delG mutation of the Connexin-26 gene in hearing impaired young children.

OBJECTIVES: Recent advances in genetic research indicate that about 50% of congenital deaf patients have a genetic background, with mutations in the Connexin-26 gene being the most frequent one. Screening methods for the genetic cause of deafness have so far mostly been based on the use of peripheral whole blood as DNA source. The use of buccal smears for the genetic screening of deaf patients presents an interesting alternative to drawing blood, especially in young children. In order to validate this method, we compared results from buccal smears from very young deaf children (age<or=3 years) and deaf patients older than 3 years with the results from blood samples deriving from the same patients. METHODS: The detection of the 35delG mutation in the Connexin-26 gene was chosen to demonstrate the method's feasibility. Blood and buccal smears were collected for genetic analysis from 29 very young deaf children (Group 1: age<or=3 years) and 31 deaf patients older than 3 years (Group 2) during their clinical pre-evaluation for cochlear implantation. Genomic DNA was isolated from blood as well as from buccal smears. Yield of both sources was determined by photometric evaluation of the isolated DNA concentration. Genomic DNA isolated from blood and buccal smears was then submitted to PCR-mediated site-directed mutagenesis followed by BS1 YI restriction and electrophoresis. The results for 35delG detection in DNA originating from blood were compared to those of buccal smears. RESULTS: Quantitative DNA analysis showed that both sources provided adequate amounts of DNA for PCR. No significant difference was found between Group 1 and Group 2 considering either the DNA amount isolated from blood or from buccal smears. In all 60 patients, DNA isolated from blood revealed the same results concerning the presence of the 35delG mutation as DNA originating from buccal smears. CONCLUSIONS: This study demonstrates that buccal smears are an adequate, reliable source of genomic DNA providing material for genetic tests that can especially help to avoid drawing blood from very young children for the genetic screening of deafness.

Adolescent↗

PubMed2005

Cholesterol granuloma of the maxillary sinus resembling an invasive, destructive tumor.

The case of a maxillary sinus cholesterol granuloma posing as a malignant tumor is presented. The patient was referred to the authors' clinic with symptoms typical of maxillary sinusitis, but physical examination suggested the presence of neoplasm. Radiology also resulted in confusing, tumor-like pictures. Histological examination of a preoperative tissue sample identified the process as a cholesterol granuloma, which was removed by a classic Caldwell-Luc operation. The patient has been symptom free since the operation. The pathogenesis of cholesterol granuloma is described, and the problems of establishing a diagnosis without preoperative histology are discussed.

Cholesterol↗

PubMed2004

Cochlear implantation for treatment-induced ototoxic deafness in Langerhans cell histiocytosis. A case report.

A case is presented where the authors carried out a cochlear implantation on a girl whose deafness was induced by cytostatic agents. The normally hearing child was diagnosed with Langerhans cell histiocytosis at the age of 3 years and received polychemotherapy for almost 2 years. By her 5th year, she started to develop a bilateral, progressive sensorineural hearing loss, necessitating a hearing aid in both ears. While her histiocytosis was cured, her hearing ultimately deteriorated to total deafness on the right and profound hearing loss on the left ear. After 3 years, her hearing aids no longer provided adequate hearing for the postlingually deafened girl. At the age of 14, a cochlear implantation was performed on her right ear with excellent results.

Adolescent↗

PubMed2003

Neural response telemetry in cochlear implant users.

Programming of multichannel cochlear implants requires subjective responses to a series of sophisticated psychophysical percepts. It is often difficult for cochlear implant patients (especially young prelinguistically deaf children) to provide adequate responses for device fitting. However, the neural response telemetry (NRT) system renders possible the measurement of the compound action potential threshold. We performed NRT examinations in 27 cochlear implant users with Nucleus 24-channel cochlear implants. Measurements were obtained from five electrodes (3, 5, 10, 15, and 20) in each patient. Our goal was to look for correlation between behavioral subjective thresholds and compound action potentials. The action potentials could be elicited in 23 patients in all measured electrodes. The NRT threshold values were highly correlated with electrical threshold levels obtained through subjective responses. Our results suggest that the electrically elicited neural responses may yield very important information for device fitting in patients with cochlear implants.

Child↗

PubMed2002

Successful cochlear implantation in a child after recovery from a head and neck malignancy: a case report.

We present the case of a successful pediatric cochlear implantation that was carried out following bilateral perilingual deafness caused by meningitis during the treatment of a childhood malignant tumor. A rhabdomyosarcoma localized in the frontobasal area was removed from the child at the age of 2 years. He then received 11 months of postoperative cytostatic treatment. A purulent meningitis developed at the end of the chemotherapy, resulting in a major-grade, bilateral sensorineural hearing loss (practically a perilingual deafness). After 6 tumor-free years and a meticulous preoperative assessment, a Nucleus 24 M cochlear implant was successfully implanted in the child's left ear. Two years after the operation, the child shows excellent hearing results and moderate speech development.

Antineoplastic Agents↗