PubMed Health⌕ Search

Biomedical subjects

J Neuburger

Publications and source records attributed to J Neuburger.

10 recordsLinked to original sources
PubMed2000

New Clarion electrode with positioner: insertion studies.

A new straight thin electrode array (universal electrode) was designed to be used together with a positioner, which will place the electrode array at the medial wall (modiolus) of the cochlea. The study objectives were to demonstrate safety and ease of insertion, tissue trauma, electrode position, and depth for universal and standard electrodes in human temporal bones; to test functional properties in cats; and to determine the surgical procedure and electrophysiological benefits in a clinical study. The cadaver study demonstrated the ease of insertion for the universal electrode and the positioner without tissue damage. An average gain of insertion depth of 180 degrees was achieved with the positioner. Animal studies demonstrated a reduction in threshold of 6 dB for the electrical auditory brain stem response (EABR). Neither additional cochlear damage nor additional connective tissue formation was found. The intraoperative human study findings showed a marked reduction of threshold for both EABR and stapedius reflex thresholds. Impedances were increased. Plain x-rays demonstrated modiolus proximity of the electrode with the positioner. The new Clarion electrode with positioner is a relatively safe design for providing modiolus proximity. The electrophysiological benefits include reduction of threshold and power consumption.

Adult↗
PubMed1999

Clinical results of the CLARION magnetless cochlear implant.

This paper reports initial results for the CLARION Multi-Strategy Cochlear Implant, presently under investigational study in Europe. A magnetless implantable cochlear stimulator (ICS) with an ear-mold-supported headpiece was designed in response to an increasing demand for a magnetic resonance imaging (MRI)-compatible cochlear implant. Surgical technique, accompanying magnetless headpiece, and MRI compatibility were evaluated in 11 deaf patients (ages 6 to 62 years) who were implanted with a magnetless Clarion implant. Because of the headset mechanics, the ICS was implanted closer behind the ear than a magnet-containing ICS. The ICS-MRI compatibility was investigated with 1.5- and 0.3-T MRI. Results showed that the surgery was relatively safe and easy to learn. The headset was stable and reliable. The MRI compatibility tests indicate that the ICS poses no contraindication for patients needing MRI. Overall, the results suggest that the Clarion magnetless cochlear implant is relatively safe and easy to implant, is MRI-compatible, and functions well with the ear-mold-supported headpiece.

Adult↗
PubMed1998

[Development and clinical testing of a non-magnetic cochlear implant. Preliminary experimental studies and surgical concept. Results in the first 10 patients].

BACKGROUND: To ensure good transmission of electromagnetic signals from the speech processor to the internal cochlear stimulator (ICS) in cochlear implants, exact alignment of the external transmitter coil over the receiver coil of the ICS is necessary. Usually this is achieved by two magnets: one implanted within the ICS, the other one integrated into the transmitter coil of the external headset. Although this principle works, there are some serious problems with the implanted magnet. The most serious of these is that it renders MRI studies potentially hazardous or impossible, or at least compromises image quality. METHOD AND RESULTS: We developed a method to eliminate the magnet. The method requires varying the implantation technique and using a special headset. The technique is easy to perform, and the headset is suitable for series production. Experience with our first patients revealed the coil alignment to be remarkably stable, even more than in patients with a cochlear implant equipped with a magnet. Results of the first ten patients are presented. DISCUSSION: Aside from eliminating the magnet, we attempted to optimize the acoustic properties of the headset. This resulted in design changes such as repositioning the microphone. Further improvements such as integration of telephone coils and special sockets to connect peripheral appliances can easily be implemented in our special headset.

Adult↗
PubMed1991

Coronary venous retroperfusion support during high risk angioplasty in patients with unstable angina: preliminary experience.

Synchronized coronary venous retroperfusion was used during coronary balloon angioplasty to support the ischemic myocardium of 20 patients with unstable angina and anatomy at high risk of a coronary event. Hemodynamics and left ventricular function were the major end points of the study. Coronary venous catheterization and retroperfusion were successfully performed in 15 patients. The target vessel was an unprotected left main artery in 2, left anterior descending artery in 10, left circumflex coronary artery in 1 and right coronary artery in 2 patients. A nonsupported balloon inflation (mean 44 +/- 13 s) was compared with a later retroperfusion-supported inflation (mean 145 +/- 21 s). Right anterior oblique left ventriculograms, aortic blood pressure, pulmonary artery pressure and thermodilution cardiac output were obtained before and during peak untreated and treated balloon inflations and on completion of angioplasty. All patients had either a baseline left ventricular ejection fraction less than 0.40 or greater than 40% of contracting myocardium estimated to be at risk for severe ischemia during angioplasty. The cardiac (liters/min per m2) and stroke work (g.m/m2) indexes decreased from mean baseline values of 2.5 +/- 0.52 and 52 +/- 15 to 1.7 +/- 0.47 and 27 +/- 12 (mean +/- SD), respectively, during nonsupported balloon inflations but decreased only to 2.1 +/- 0.52 (p less than 0.01 vs. nonsupported) and to 36 +/- 14 (p = 0.01 vs. nonsupported), respectively, during retroperfusion-supported inflations. Ejection fraction (n = 8) decreased from a baseline value of 55 +/- 13% to 27 +/- 7.3% during nonsupported inflations but only to 39 +/- 10% during retroperfusion-supported inflations (p = 0.01 vs. nonsupported). Regional wall motion (area change) in the ischemic (target) region was reduced from a baseline value of 49 +/- 17% to 11 +/- 16% during nonsupported inflations but only to 27 +/- 15% during retroperfusion-supported inflations (p less than 0.01 vs. nonsupported). All but two patients had a favorable hemodynamic response to retroperfusion. There were no serious adverse effects related to the procedures and no hospital deaths. It is concluded from this preliminary study that coronary venous retroperfusion appears to be safe, to provide hemodynamic support and to improve left ventricular function during angioplasty in patients with unstable angina and anatomy at high risk of a coronary event.

Angina, Unstable↗
PubMed1991

Protein kinase C and alpha 2-adrenoceptor-mediated inhibition of noradrenaline release from the rat tail artery.

In isolated rat tail arteries preincubated with [3H]noradrenaline, electrical field stimulation evoked the overflow of tritium. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activating phorbol ester, time-dependently increased the overflow at 1 mumol/L but not at 0.1 mumol/L. In contrast, the overflow was not altered by phorbol 13-acetate (PA, 1 mumol/L), which does not influence the activity of PKC. Polymyxin B (70 mumol/L), an inhibitor of PKC, depressed the overflow when given alone and, in addition, attenuated the effect of PMA, 1 mumol/L. The selective alpha 2-adrenoceptor agonist B-HT 933 depressed the overflow; PMA, 1 mumol/L, did not interfere with the effect of B-HT 933, 10 mumol/L. The results provide evidence for the participation of prejunctionally located PKC in the release of noradrenaline. However, PKC does not seem to be involved in the alpha 2-adrenoceptor-agonist-mediated inhibition of noradrenaline release.

Adrenergic alpha-Agonists↗