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Results for “Electrodes, Implanted”

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At least 19 recordsLinked to original sources
PubMedDate not supplied

Experience with implanted electrodes.

Implant units, manufactured by Medtronic, Inc., have been implanted in 31 patients for treatment of drop-foot. The principal problem encountered in this series was inflammatory reaction. This was observed in seven patients, and was serious enough in five to require removal of the implant. On the positive side, there have been no failures of the implanted equipment for periods of up to 7.3 years, although there is currently a question on one patient. There has also been no documented damage to the nerve from chronic stimulation. Fine wire elctrodes have been implanted intraneurally in a series of animals and in three patients. Preliminary results look encouraging, and this approach seems to hold considerable promise for a new generation of electrode design.

Amputees↗
PubMed1979

Effect of lactulose, neomycin and antacid on colonic pH recorded continuously with an implanted electrode.

Colonic pH was continuously monitored by a pH electrode implanted in the transverse colon of rats over a 24-hour period. Lactulose significantly reduced the colonic pH to 5.37 +/- .39 from a fasting value of 6.77 +/- .75. Pretreatment with neomycin or concomitant use of a nonabsorbable antacid prevented lactulose-induced reduction in the colonic pH. The clinical implication of the study is that combined use of lactulose with neomycin or high doses of non-absorbable antacids in the treatment of chronic portasystemic encephalopathy may be undesirable.

Animals↗
PubMed1979

Electrode implantation and electrostimulation in rabbits.

The investigators studied functional electrostimulation by means of an implanted electrode placed around the peroneal nerve in rabbits. Current pulses were administered from a stimulating unit outside the body, via a connecting skin plug and subcutaneous leads to the electrode. It is concluded that if this form of stimulation is to be praticable without undesirable results, certain mechanical problems require further study.

Animals↗
PubMed1979

Long-term electrode implantation for recording cochlear electrical activity in guinea pigs.

Comparative measurements of the cochlear electrical activity over prolonged periods require long-term implantation of electrodes. During this time, changes in the electrode recording ability and/or impairment of the sound-conducting system, could erroneously be attributed to the experiment. To avoid this risk, an easy and reliable technique is described. The procedure uses the Fallopian canal as a route by which to approach the cochlear potentials' generators, while leaving the middle ear untouched.

Action Potentials↗
PubMed1978

Cerebral tissue response to electrode implantation.

Tissue response to platinum electrodes was assessed after an eight-day implantation period. The regions of study included the cortical areas at the opercular gyri and at the sulcus parieto-occipitalis externus, as well as the sub-cortical white matter in these cases. Perivascular and intraparenchymal hemorrhagic lesions as well as edematous changes characterized both by extensive intra and extracellular swelling were noted. Numerous phagocytic elements and degenerative strucutres were present at the electrode/parenchymal interface. Tissue alterations were asymmetrical as observed both around and at the tip of the implanted electrode. The parenchymal alterations extended from 0.2mm to 3.5mm distance from the electrode path/parenchymal interface. Greater tissue involvement was found in the subcortical white matter as compared to the adjacent cortical gray matter.

Animals↗
PubMed1976

[Left persisting, singular superior vena cava and pacemaker electrode implantation by right cephalic vein].

We are reporting on a case of a singular left upper vena cava with an outlet into the right atrium by a large sinus coronarius (that means, the right vena cava is lacking totally). In spite of the well-known anomaly of the upper vena cava, we successfully implanted a stimulating electrode by the typical access through the right vena cephalica through the right sinus coronarius into the right ventricle. Except of a thrombosis of the rightsided deep venous system of the arm, no complications were to be complained within sixteen months. We know from literature, that within four more cases this transvenous access has been used in pacemaker-therapy. Various complications have been discussed. Before definately implanting an electrode, one should secure severely, if there is any special anomaly of the upper vena cava. In case of the here described, but very rare anomaly of the vana cava, it is to be examined thoroughly, whether an implantation of a transvenous electrode is indicated or, eventually, a myocardial implantation should be preferred.

Female↗
PubMed1977

Fabrication of pH-sensitive implantable electrode by thick film hybrid technology.

We report preliminary results of our experiments directed at fabricating pH-sensitive electrodes suitable for in vivo use by means of thick film screening techniques. Our results show that glass membranes of suitable thickness and possessing nearly theoretical sensitivity to pH can be fabricated by this process. A hybrid electrode structure permits the incorporation of a source follower FET amplifier directly adjacent to the pH membrane, significantly reducing response time and noise pick-up. Extension of the basic electrode structure to accommodate membranes sensitive to other ions is discussed.

Biomedical Engineering↗
PubMed1976

Implantable electrode for recording nerve signals in awake animals.

An implantable electrode assembly consisting of collagen and metallic electrodes was constructed to measure simultaneously neural signals from the intact nerve and bioelectrical noises in awake animals. Mechanical artifacts, due to bodily movement, were negligibly small. The impedance of the collagen electrodes, measured in awake cats 6-7 days after implantation surgery, ranged from 39.8-11.5 komega at a frequency range of 20-5 kHz. Aortic nerve activity and renal nerve activity, measured in awake conditions using the collagen electrode, showed grouped activity synchronous with the cardiac cycle. Results indicate that most of the remal nerve activity was from postganglionic sympathetic fibers and was inhibited by the baroceptor reflex in the same cardiac cycle.

Animals↗
PubMed1976

The ultrastructure of the sheath around chronically implanted electrodes in brain.

Insulated, bipolar stainless steel electrodes were chronically implanted in various regions of the cat brain and the long-term structural changes in the tissue surrounding the electrodes were studied by light and electron microscopy. A sheath surrounded and separated the electrode from normal grey or white matter. A layer of foreign body giant cells of variable thickness was formed adjacent to the electrode. This layer was attenuated in some places so that it was unrecognizable by light microscopy. The bulk of the sheath structure consisted of collagen fibrils, leptomeningeal cells and hypertrophied astrocytes. Areas consisting of modified leptomeningeal cells with long thin processes we designated as spongy areas. These have not been previously reported using the electron microscope. Glycogen bodies were seen in leptomeningeal cells. Astrocytes became greatly enlarged and were more numerous in and around the sheath. Oligodendrocytes contained lamellar bodies, and direct continuity was shown between a lamellar body and an adjacent myelin sheath. Myelin was seen in abnormal sites (around oligodendrocytes and neurons) and in unusual configurations. Neuronal changes near the sheath included whorls and stacks of modified endoplasmic reticulum and the presence of cytoplasmic nucleolus-like bodies. Reactive, regenerative and degenerative axons were observed. Blood vessels were more numerous in the sheath and surrounding tissue than normal. Perivascular spaces were prominent even around capillaries and often plasma cells and monocytes were in these spaces. As compared to normal tissue the extracellular space is noticeably increased. Electrodes passing through ventricles were surrounded with a sheath covered with ependymal cells. This sheath was comparable in structure to the sheath present around the electrode in other locations.

Animals↗
PubMed1977

[The management of urinary and fecal incontinence due to a neurinoma of the cauda equina with an electrode implanted in the pelvic muscles (Caldwell) (author's transl)].

A woman, aged 49, had a complete sensory and motor deficit of the S2-5 segments with urinary and fecal incontinence due to a neurinoma of the cauda. A Caldwell electrode was implanted surgically into the muscles of the pelvic floor in April 1974. The patient was observed for 2 years thereafter and had an excellent result. The medical and technical problems of treating urinary and fecal incontinence due to a lower motor neuron lesion of S2-5 can be handled satisfactorily with an implanted electrode.

Cauda Equina↗