Biomedical subjects

O Adunka

Publications and source records attributed to O Adunka.

At least 19 recordsLinked to original sources

PubMed2005

[Adonco. A clinical-scientific database system for the acquisition and analysis of oncologic data in head and neck regions].

BACKGROUND: Our aim was to design and develop a computer database system for head and neck cancer patients for clinical and scientific use. METHODS: A relational database based on Filemaker Pro 6.0 was developed and integrated into our local network. Its precise and easy to handle interface should allow a quick overview of the patient's oncological data. An automatically generated letter was integrated to enhance patient care. For evaluation purposes, statistical analysis functions were incorporated. RESULTS: Over a 7 month period, about 300 patient records were available through the local network. The automated letter function and the well organized display resulted in more efficient patient care. Additionally, the quality of the information presented to referring physicians increased. Statistical analysis provided by the database was reliable and easy to export. CONCLUSIONS: We developed an oncology database for clinical and scientific use and integrated it into our patient documentation system. The combination of clinical and scientific features proved to be very effective in daily patient care routine and research.

Algorithms↗

PubMed2005

[Cochlear implantation with preservation of residual deep frequency hearing].

BACKGROUND: The aim of the present paper is to evaluate the clinical parameters in patients implanted for combined, ipsilateral electric-acoustic stimulation of the auditory system. METHODS: A total of 18 patients with residual deep frequency hearing were implanted with a Combi 40+cochlear implant (MED-EL, Austria). Insertion depths ranged from 18 to 22 mm (360 degrees ). A modified surgical technique should contribute to hearing preservation in low frequency regions of the cochlea. Pure-tone audiometric thresholds were measured pre- and postoperatively. A speech audiometric evaluation was performed on two subjects. RESULTS: Utilizing adapted surgical procedures, the preservation of low frequency hearing was accomplished in 16 of 18 subjects (88.9%). Seven (38.9%) patients had complete and nine (50.0%) partial preservation of residual hearing. The speech discrimination scores of two patients documented an increase in sentence intelligibility when compared with only the cochlear implant. CONCLUSIONS: Hearing preservation in cochlear implant surgery is possible. Insertions of 360 degrees provide a full functioning cochlear implant to stimulate sufficient neural structures for above average discrimination scores with the implant alone. A synergistic effect of the electric and the acoustic stimulation modes leads to high discrimination scores in background noise.

Adult↗

PubMed2005

[How does a cochlear implant speech processor work?].

Cochlear implants have become a standard treatment modality for sensorineural hearing loss. In this review article, assembly and function of a cochlear implant are described. Cochlear implants replace the normal inner ear by transforming acoustic sound signals into electric stimuli and deliver these to the auditory nerve. Speech processors translate the acoustic signal of the microphone into one that fits electrostimulation of the auditory system. In multiple steps, the signal has to be analyzed and processed to fit the demands of electrical stimulation. The speech processor then sends commands and the energy for stimulation to the implanted parts via a transcutaneous high frequency radio link. The implant refers the information as electrical stimuli to each electrode contact.

Analog-Digital Conversion↗

PubMed2005

Evaluating cochlear implant trauma to the scala vestibuli.

OBJECTIVES: Placement of cochlear implant electrodes into the scala vestibuli may be intentional, e.g. in case of blocked scala tympani or unintentional as a result of trauma to the basilar membrane or erroneous location of the cochieostomy. The aim of this study was to evaluate the morphological consequences and cochlear trauma after implantation of different cochlear implant electrode arrays in the scala vestibuli. DESIGN: Human temporal bone study with histological and radiological evaluation. SETTING: Twelve human cadaver temporal bones were implanted with different cochlear implant electrodes. Implanted bones were processed using a special method to section undecalcified bone. MAIN OUTCOME MEASURES: Cochlear trauma and intracochlear positions. RESULTS: All implanted electrodes were implanted into the scala vestibuli using a special approach that allows direct scala vestibuli insertions. Fractures of the osseous spiral lamina were evaluated in some bones in the basal cochlear regions. In most electrodes, delicate structures of the organ of Corti were left intact, however, Reissner's membrane was destroyed in all specimens and the electrode lay upon the tectorial membrane. In some bones the organ of Corti was destroyed. CONCLUSIONS: Scala vestibuli insertions did not cause severe trauma to osseous or neural structures, thus preserving the basis for electrostimulation of the cochlea. However, destruction of Reissner's membrane and impact on the Organ of Corti can be assumed to destroy residual hearing.

Cadaver↗

PubMed2004

[Evaluation of an electrode design for the combined electric-acoustic stimulation].

BACKGROUND: The objective of this study was to assess the intracochlear position and the extent of trauma to cochlear structures using the C40(+) M electrode (MED-EL, Innsbruck, Austria), which was especially designed for the combined electric acoustic stimulation. METHODS: Five human temporal bones were implanted using a standard cochlear implant procedure featuring mastoidectomy, posterior tympanotomy, and promontory cochleostomy. For the cochleostomy, an inferior approach with preservation of the endosteum of the cochlea was used to contribute to hearing preservation in the in vivo condition. RESULTS: All insertions of the new electrode array were performed into the scala tympani of the cochlea. The average insertion depth was 288 degrees. Apically, 4 of the 5 implantations were completely atraumatic. One bone showed a rupture of the basilar membrane only at the tip of the electrode. However, 4 of the 5 arrays produced severe trauma to basal cochlear structures. Two pathomechanisms, the direct traumatization through drilling of the cochleostomy or the indirect traumatization via buckling of the array could be distinguished. CONCLUSIONS: Due to the reduced contact spacing and its flexible body, the C40(+) M electrode is suitable for cochlear implantations with hearing preservation and combined electric and acoustic stimulation of the auditory system. Modifications of the surgical pathway to the cochlea should help to minimize the risk of basal cochlear trauma.

Basilar Membrane↗

PubMed2001

Perimodiolar electrodes in cochlear implant surgery.

Perimodiolar-positioned cochlear implant electrodes have been developed in order to bring the electrode contacts as close as possible to the spiral ganglion cells, which are the target of electrostimulation. This results in lower electrical thresholds, higher dynamic ranges and less channel interaction when compared with normal implant electrodes which are usually located peripherally within the scala tympani. In this study we evaluated 4 different types of perimodiolar electrode: the Clarion Preformed electrode, the Clarion Preformed electrode with positioner, the Nucleus Contour electrode and the Med-El Perimodiolar Combi 40 electrode. These devices require different approaches to achieve a perimodiolar electrode position. The electrodes were inserted in fresh human temporal bones. After processing these bones with the electrodes in situ by employing a sawing, grinding and polishing technique, the inner ear structures as well as the electrode positions could be evaluated in detail. All electrode types studied had a more or less perimodiolar position; however, each type produced a certain amount of trauma to cochlear structures which is discussed in relation to mechanical properties. Further human temporal bone studies with improved perimodiolar cochlear implant electrodes are necessary in order to find an optimized type of electrode.

Cochlea↗

PubMed2000

[Rehabilitation of hearing-impaired patients with cochlear implants: a review].

The aim of this paper is to provide an overview of the cochlear implant. The history of this entity is traced from the early development of implants, involving the stimulation of the hearing nerve, up to the currently available standard multichannel implants. The physiological background is also elucidated. A cochlear implant consists of an implantable portion which lies within the ear, and of parts that are worn externally on the body. Differences between the first implants and those now in use are as follows: transcutaneous information and energy transmission, the position of the electrode in the ear, and the configuration of the electrode. Differences between the currently available implants mainly concern the number of electrodes, speech coding strategies and the mode of electrode stimulation. Almost all of the most recent implants are equipped with electrodes that are implanted in the tympanic scale of the cochlea.

Acoustics↗

PubMed2000

[Cochlear implantation--the Viennese surgical technique].

The aim of the study was to report the current surgical procedure that has been established on the basis of about 200 implantations with the Combi 40/40+ implant system. The outstanding features of this procedure are the skin incision and the fact that the electrode can be inserted up to a depth of 34 mm into the cochlea. In order to provide better magnetic positioning of the external parts, a flap-reducing technique may be required. For insertion we used a soft surgery method to preserve structures within the cochlea. In some cases we were able to inspect the cochlea with microendoscopes, which helped to prevent electrode kinking, since fibrous obliterations were found before the insertion. For electrode fixation in the mastoid cavity we used bone paté.

Austria↗

PubMed2000

[Intracochlear position of cochlear implant electrodes].

The insertion of cochlear implant electrodes in human temporal bones may be associated with the destruction of structures within the cochlea. The aim of this study was to measure such insertional trauma by means of histologic processing of implanted human temporal bones following implantation of a Combi 40/40+ electrode array (Med-El, Innsbruck). We implanted 6 human temporal bones with original electrodes (3 with Combi 40 and 3 with Combi 40+). In 4 bones Healon was used for electrode insertion. The histological investigation was performed after radiographic evaluation of the position of the electrode. For the histological procedure we used a technique which keeps the electrodes in position within the cochlea. In these slides we could clearly identify the electrodes in the tympanic scale. When inserted properly (point of first resistance) no trauma occurred in the basal portion of the cochlea and minimal trauma in the middle portion of the cochlea.

Cochlea↗

PubMed2000

[Preoperative imaging of the inner ear prior to the implantation of a multichannel cochlear implant using computed and MR technology].

CT and MRT are now standard examinations prior to insertion of a cochlear implant. Both methods have advantages and disadvantages in terms of discovering potentially pathological structures in the inner ear. The aim of this study was to evaluate the pros and cons of using CT and MRT before cochlear implantation. CT is usually performed using axial planigraphic planes. Like MRT, bone-specific CT is helpful in the diagnosis of congenital and acquired changes within the inner ear. Congenital defects in the meatus acusticus internus, the endolymphatic duct and sac, the cochlea and the vestibulum can be diagnosed and also quantified. Infectious morphologic changes can be seen on CT images in their terminal residual state (sclerotic tissue). However, acute inflammation and fibrotic tissue is not visible on CT. T2-specific MRT images are very fluid sensitive and play a major role in preoperative cochlear implant diagnosis. This examination demonstrates fluid within the peri- and enolymphatic cave and permits the diagnostician to determine whether congenital or acquired diseases have destroyed such fluid-filled cavities. In order to demonstrate pathological changes in the temporal bone and neural structures in the inner ear, MRT is the preferred method. Displaying the modiolus and the cochlear nerve is extremely important because, in their absence, a cochlear implantation may be contra-indicated. MRT also demonstrates other neural structures such as the facial nerve. This information may be important for the surgeon, e.g. the state of the pneumatic system in the mastoid cavity (which is best visualised by bone-specific CT).

Cochlear Implantation↗

PubMed2000

[Speech discrimination in post-lingually deaf patients with cochlear implants].

The aim of this study was to measure the speech discrimination performance of postlingually deaf patients using the Combi 40/40+ cochlear implant (Med-El, Innsbruck). The speech perception performance of 37 adults was tested over a time span of three years. We used a standardised test battery comprising number, monosyllable, sentence, consonant and vowel discrimination tests. Testing was performed immediately after initial fitting and 1, 3, 5, 12, 24, and 36 months thereafter. The average correct answers for all tests were as follows: right after the implantation 29.1%, after 1 month 46.7%, after 3 months 53.9% after 1 year 63.5% and after 3 years 68.5%. Some patients reached a number discrimination rate of 100%. The discrimination for monosyllables averaged 41.1% two years after implantation. The results demonstrated continuous improvement of speech perception, even after three years following implantation.

Adult↗

PubMed2000

[Hearing and speech discrimination scores of prelingually deaf children with cochlear implants].

The goal of this study is to report mean values of speech perception performance in prelingually deaf children who received a Combi 40/40+ cochlear implant. Thirty-one patients were included in the study. The time span ranged over 3 years, during which time the Evaluation of Auditory Responses to Speech (EARS) test battery was used in the children. The EARS battery contains 4 measures of closed-set speech perception and 3 open-set tests. The mean test results exhibited steady improvement in all parts of the EARS test battery, even up to 3 years post-implantation. The mean preoperative scores were 0.3%, increasing to 92.3% at 36 months post-implantation for the best children. Results for the closed-set testing measures were most encouraging, with some children reaching fairly high levels of speech perception and achieving scores as high as 98.7% at the 36-month evaluation. The congenitally and prelingually deaf children in our study showed continuous improvement in both closed and open set speech perception following cochlear implantation, although individual variations in performance were noted.

Age Factors↗

PubMed2000

[Speech discrimination in noise for patients with cochlear implants].

The aim of the study was to evaluate the speech discrimination ability of postlingually deaf adults implanted with the Combi 40 cochlear implant in noise and to compare the results with the speech discrimination ability of patients provided with hearing aids. The 12-month postoperative hearing performance of 12 consecutive patients was tested using a sentence discrimination test in quiet and noise. The results of the present study demonstrate that all patients obtained substantial benefit from their implants even in situations coupled with noise. The speech understanding of cochlea-implanted patients appears to be better than that of patients provided with hearing aids. Very high scores (mean, 40.2%) were achieved at a signal-noise ratio of 15 dB.

Adult↗

PubMed2000

[Preoperative diagnostic procedures before cochlear implantation].

About 200 patients are considered each year for cochlear implant recipiency. Only 1/4 of these candidates actually receive an implant. The aim of the study is to discuss the preoperative procedure we use, which is aimed to exclude patients who would not benefit from an implant. A cochlear implant is an example of very expensive high-profile medical therapy, a single implant costing about 280,000 Austrian schillings. The aim of the preoperative diagnostic procedure is to select the right patients, with a view to providing the best audiologic outcome. During the past 20 years, important parameters have been identified to determine suitable patients. Candidates for a cochlear implant are infants and children (independent of the etiology of deafness or high-grade hearing loss), as well as postlingual deaf adults. Congenitally deaf adults or teenagers are considered unsuitable to receive an implant.

Acoustic Impedance Tests↗

PubMed2000

[Postoperative imaging and evaluation of the electrode position and depth of insertion of multichannel cochlear implants by means of high-resolution computed tomography and conventional X-rays].

Following cochlear implantation, postoperative imaging of the electrode is very important in order to measure the depth of insertion and the position of the electrode, so that kinking and incorrect electrode placement can be clearly identified. The aim of this study was to outline the diagnostic value of CT and conventional X-ray for these parameters. For this purpose we obtained radiographs of patients who had received a cochlear implant. Computed tomography was performed by obtaining axial sections. For conventional X-ray we used digital imaging, utilising a modified Chausse III projection. The images were then rated according to electrode position, insertion depth and possible complications. We also measured the radiation dose using a dummy and evaluated the cost of each examination. Both examinations permit excellent identification of electrode position and insertion depth. However, the depth of insertion can be measured much more accurately by means of digital X-ray. The radiation dose of CT was 230 times higher than that of conventional X-ray and the cost of CT 5 times that of digital X-ray.

Austria↗

PubMed2000

[Clinical utilization of magnetic resonance imaging for patients with cochlear implants].

To date, MR imaging is absolutely contraindicated in cochlear-implanted patients. The aim of this study is to document the potential value of MR imaging in such patients, without injurious or side effects and without technical device failure. After in vitro experimental testing, 25 cochlear implanted patients underwent MRI. Radiological evaluation was also possible. The use of 1-Tesla fast spin echo sequences minimised artifacts. All cochlear implants are still in working order; no changes in fitting data or a reduction in speech understanding were observed. MR helped to avoid other invasive medical procedures.

Austria↗

PubMed2000

[Cochlear implantation and auditory feedback].

The aim of the present study was to evaluate the short term effect of cochlear implantation on the fundamental frequency and the articulation of 13 patients. This investigation objectives for the first time the changes of fundamental frequency and articulation in cochlear implant patients. All postlingual deaf patients were provided with a Combi 40+ cochlear implant. Voice recording was performed pre- and three months post-implantation. The voice data was analyzed using the "X-Tool" software. The results show that 38% of the patients had a significant (p < 0.05) decrease of F0 mean three months after implantation. A postoperative decrease of F0 towards the normal range was observed generally in all patients. Spectographs pre- and post-implantation showed that the articulation improved already 3 months after partial restoration of auditory feedback. A large variability of F0 was noticed among the deaf subjects, but no correlation to the duration of deafness could be established.

Adolescent↗

PubMedDate not supplied

Audiological performance with cochlear reimplantation from analogue single-channel implants to digital multi-channel devices.

Cochlear implantation has been performed for almost two decades at the Vienna University Hospital. Until 1994, single-channel implants were used (Ball-Electrode, SC6/2SC6, Vienna/Epoxy, Med-E1, Innsbruck, Austria). The development of multi-channel devices (Combi 40/40+), which provide significantly improved speech recognition performance, led to the reimplantation of some patients who had previously received single-channel implants. It was of particular interest to find out if there was a deterioration of the central "learning process" by the reimplantation from the analogue single-channel device to the tonotopic pulsatile multi-channel stimulation. In this study, we attempted to demonstrate that single-channel implants have an impact on the neural organisation of the auditory system. Two groups of post-lingually deaf adult patients were tested. Group A had previously received single-channel implants and were reimplanted with the new Combi 40/40+ cochlear implant (Med-E1, Innsbruck, Austria) in the same ear. Group B was implanted only with the Combi 40/40+. Six different speech recognition tests were subsequently performed on all patients, and the two groups performed similarly. Furthermore, it was discovered that group A obtained significant speech recognition improvement (p<0.05) with monosyllabic words and number tests 1 month following reimplantation.

Acoustic Stimulation↗