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Biomedical subjects

A Büchner

Publications and source records attributed to A Büchner.

11 recordsLinked to original sources
PubMed2003

[Cochlear implants in adults: indications and realizations. Part I: Diagnosis, operation techniques and results].

From the technical point of view, cochlear implant (CI) surgery in adults is a well established procedure. Pre- and postoperative evaluation, surgical approach and rehabilitation programs are standardized, presenting CI as a low risk procedure with rare complications similar to those of middle ear surgery. Modern advanced CI devices offer technical reliability and multiple speech encoding strategies and recently, even small processors which are worn behind the ear. Further technical advances are continuously available, even for implanted patients. Upgrading is usually easy because the outer parts of the implant are exchangeable and software upgrades can be transmitted transcutaneously to the implant. Assuming that medical and rehabilitation requirements are available, there are only very few indications against CI in adults. Candidate patients should therefore be transferred to CI-centres where a decision can be taken depending on presurgical evaluation results.

Adult↗
PubMed2003

[Cochlear implants in adults: indications and realization. Special cases and technical parameters of the implantation systems].

From the technical point of view, cochlear implant (CI) surgery in adults is a well established procedure. Pre- and postoperative evaluation, surgical approach and rehabilitation programs are standardized, presenting CI as a low risk procedure with rare complications similar to those of middle ear surgery. Part 1 described the diagnostics, surgical procedure and possible complications. The second part will cover the contraindications, special cases as well as the technical parameters of the modern implant system.

Adult↗
PubMed2002

The results in patients implanted with the nucleus double array cochlear implant: pitch discrimination and auditory performance.

OBJECTIVE: In patients with total or surgically inaccessible cochlear obliteration, only a reduced number of active electrodes can be inserted with standard cochlear implants, resulting in below average auditory performance. Therefore, a special implant with two electrode arrays was developed on the basis of the Nucleus 22 cochlear implant, the socalled Double Array. One electrode array with 11 active electrodes is inserted into the basal turn of the cochlea, while the second array with 10 active electrodes is inserted into the second turn. The Double Array is now available on the basis of the more advanced Nucleus 24 with 11 active electrodes on each array and two reference electrodes, one at the case and the second one an additional ball electrode, which is placed under the temporalis muscle. For device description and surgical technique see Lenarz et al. (2001). This paper presents psychophysical data on pitch discrimination and auditory performance of patients implanted with a Double Array on the basis of the Nucleus 22. STUDY DESIGN: A prospective intra-individual study using a Latin square paradigm was performed in six adult patients with obliterated cochlea who received the Nucleus 22 Double Array. After appropriate fitting and loudness balancing, patients were tested either with the basal, the apical or both electrode arrays. Apart from auditory performance tests including numbers and monosyllable word tests, pitch discrimination was determined with a defined procedure. RESULTS: When activating each array alone, auditory performance was better with the basal array than with the apical array. Both arrays together showed marked improvement compared with the basal array, indicating an additional effect of the second array. Pitch discrimination was significantly better for the electrodes in the basal turn than in the second turn, indicating differences in electrical excitation of the auditory nerve fibers. Pitch discrimination was positively correlated with auditory performance data. CONCLUSION: The additional apical array leads to significant improvement in auditory performance in patients with obliterated cochleae by increasing the number of intracochlear electrodes. Despite reduced pitch discrimination, the apical array provides important information for speech recognition. For this reason the Double Array provides a profound advantage for patients with obliterated or surgically inaccessible cochleae.

Acoustic Stimulation↗
PubMed2001

The nucleus double array cochlear implant: a new concept for the obliterated cochlea.

OBJECTIVE: To increase the number of intracochlear electrodes that may be inserted into a totally obliterated cochlea, a special implant has been developed in collaboration with Cochlear Limited. This implant features two separate electrode carriers containing 11 and 10 active electrodes, respectively, as well as a reference electrode located on the receiver-stimulator package. The potential stimulation modes available with this device therefore include monopolar and bipolar stimulation, and stimulation between both arrays. SURGICAL TECHNIQUE: A cochleostomy anterior to the round window provides access to the basal turn (both the scala tympani and the scala vestibuli), and new built connective tissue and bone can be removed until the anterior wall of the basal turn is approached. A second cochleostomy is performed at the second turn caudal of the cochleariform process and 2 mm anterior of the oval window after removal of the incus. New tissue should also be removed if necessary. The two electrode carriers are then placed into the scala tympani of the basal and the scala vestibuli of the second turn, respectively. The remaining surgical procedure is identical with that used for cochlear implantation in patients without obliterated cochleas. PATIENTS: In this clinical study, 10 patients aged 32 to 66 years with an obliterated cochlea each received a double array cochlear implant. All patients had total obliteration of the basal turn either on preoperative imaging or during surgery. Intraoperatively, the second turn was not obliterated in only 4 of 10 patients. Postoperatively, a standard audiologic test battery was used to determine auditory improvement over time. POSTOPERATIVE RESULTS: All patients achieved significantly improved speech understanding when the additional apical electrode array was used, compared with the use of each electrode array independently. No complications occurred. CONCLUSION: In patients with a totally obliterated cochlea, the number of intracochlear electrodes can be increased by use of the Nucleus double array implant. As a result, patients achieve significantly better auditory results.

Adult↗
PubMed1999

[The Nucleus Double Array Cochlear Implant: a new concept in obliterated cochlea].

AIM: In order to increase the number of intracochlear electrodes to be inserted into a totally obliterated cochlea a special implant has been developed in collaboration with Cochlear Ltd. The implant features two separate electrode carriers containing 11 and 10 active electrodes, respectively, and a reference electrode on the receiver stimulator package. The potential stimulation modes include monopolar and bipolar stimulation as well as stimulation between both arrays. SURGICAL TECHNIQUE: A cochleostomy at the round window provides access to the scala tympani. Newly formed bone is removed as far as the anterior portion of the basal turn. Care is taken to identify and preserve the osseous border of the cochlea. A second cochleostomy is performed immediately caudal to the cochleariform process after removal of the incus. New tissue can be removed here in the same way. The two electrode carriers are then placed into the first and the second turn respectively. The remaining procedure corresponds to the procedure for cochlear implantation in cases in which the cochlea is not obliterated. PATIENTS: For the purpose of a clinical study n = 10 patients aged between 32-66 years with an obliterated cochlea were fitted with a double array cochlear implant. All patients showed signs of total obliteration of the basal turn either in preoperative imaging or during surgery. Intraoperative inspection revealed that the second turn was not obliterated in 4 of 10 patients. POSTOPERATIVE RESULTS: Postoperatively, a standard test battery was used to determine auditory performance over a period of time. All patients achieved significantly better speech understanding due to the additional apical electrode array. No complications occurred. CONCLUSION: In cases involving an obliterated cochlea, the number of intracochlear electrodes can be increased with the double array implant. As a result, the patients achieve significantly better auditory results.

Adult↗
PubMed1992

[The content of DNA, RNA and protein and the fresh weight:DNA, protein:DNA and RNA:DNA ratios in tissue of male calves, bulls, short-scrotum bulls and oxen during the growth period].

In male calves, in bulls, in short scrotum bulls and in oxen of different age the content of DNA, RNA and protein in various tissues (cerebrum, cerebellum, spinal cord, ventricles, lung, liver, cortex of the kidney, spleen, testicles, M. semimembranosus) was analysed. The fresh weight: DNA-, the protein: DNA- and the RNA: DNA-ratios were calculated. In the age of 78 weeks the short scrotum bulls had a body weight of 577 +/- 44, the bulls of 550 +/- 21 and the oxen of 462 +/- 41 kg. The testicles of the short scrotum bulls were smaller than that of the bulls. The differences in the content of DNA, RNA and protein per g tissue between male calves, bulls, short scrotum bulls and oxen of the same age were in part significant. The total content of DNA, of RNA and of protein for the 78 weeks old as well as the number of nuclei of the lung, the liver, the spleen and the testicles for the 6 and 78 weeks old animals were calculated. The biochemical parameters can be used for the characterization of the inhibition of growth of the different organs of calves and cattle by malnutrition and diseases.

Animals↗