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Results for “Electrodes, Implanted”

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At least 55 records · Page 3Linked to original sources
PubMed1986

Effects of chronic electrode implantation on dopaminergic neurons in vivo.

The present study evaluated the effects of chronic electrode implantation on stimulus-dependent increases of the dopamine (DA) metabolite dihydroxyphenylacetic acid (DOPAC) in relationship to a well characterized in vivo model which used electrical stimulation from acute electrode placements in the nigro-striatal pathway. Five days after bipolar electrodes were implanted into the nigro-striatal pathway, non-contingent electrical stimulation (100 microA, 25 Hz, 1.5 msec duration, 20 min session) did not change DA or DOPAC concentrations in the caudate nucleus, nucleus accumbens, or olfactory tubercles, whereas the same stimulation from acute electrode placements causes significant ipsilateral increases in caudate DOPAC. Although DOPAC concentrations did not change when these chronically implanted electrodes were stimulated, similar chronic electrode placement supported intracranial self-stimulation (ICSS). In order to examine the effects of self-stimulation on DOPAC concentrations, five ICSS test groups were established for comparison: implanted only, trained only, minimum response rate, 50% maximum response rate and maximum response rate. Following a 50 min test session, a comparison of either DA, or DOPAC concentrations across the different ICSS conditions revealed no change for the caudate nucleus, nucleus accumbens or olfactory tubercles. Likewise, there was no change between the stimulated and unstimulated sides within each ICSS group. When a comparison was made between implanted only and maximal ICSS response rate groups for changes in DA or DOPAC concentrations in the frontal cortex, no differences were found. Apparently, chronic electrode implantation abolished the ability to electrically stimulate nigro-striatal dopaminergic neurons under non-contingent conditions, and the relationship between dopaminergic neurons and ICSS appears to be indirect in nature.

Animals↗
PubMed2006

Efficacy of and morbidity associated with stereoelectroencephalography using computerized tomography--or magnetic resonance imaging-guided electrode implantation.

OBJECT: The purpose of this paper was to define the general efficacy of and morbidity associated with stereoelectroencephalography using modem methods of imaging and to particularize the risks related to specific lobes of the brain. METHODS: All patients admitted to the Montreal Neurological Institute who had undergone either computerized tomography- or magnetic resonance imaging-guided electrode implantation by one surgeon (A.O.) were reviewed. The procedure was considered efficient if the obtained information was sufficient to make a decision either in support of or against surgery. Two hundred seventeen patients underwent 224 implantations with 3022 electrodes. Complications related to each lobe were as follows: temporal lobe, two abscesses (0.54%); frontal lobe, one abscess and three hematomas (1.4%); and occipital lobe, one hypointense lesion found 1 week after electrode explantation (2.6%). Significant risk factors associated with hematomas were implantation in the frontal lobe (p < 0.05) and the use of four or more implanted electrodes (p < 0.025). General complications included the following: 26 patients, psychiatric symptoms during monitoring; one patient, meningitis; four patients, scalp cellulitis; and two patients, hemiparesis during angiography in the early 1980s. One of these latter patients maintained a mild hemiparesis and represents the only case of permanent neurological sequela in the entire series. Data obtained during recordings supported an indication for surgery in 178 patients (79.5%), excluded a surgical option in 37 patients (16.5%), and were unsatisfactory in nine patients (4%). Thus, the overall efficacy as defined previously was 96%. CONCLUSIONS: Stereoelectroencephalography is an efficient procedure with low associated morbidity. Bilateral exploration of the temporal lobes has a morbidity rate of approximately 1%. A higher risk of hematomas occurs with the implantation of four or more electrodes in the frontal lobes.

Adult↗
PubMed1999

Chronic electrode implantation entails epileptiform field potentials in rat hippocampal slices, similarly to amygdala kindling.

Evoked field potentials were recorded in the CA3, CA1 and dentate gyrus (DG) of hippocampal slices from amygdala kindled, non-stimulated amygdala electrode-implanted, and non-implanted age-matched rats to evaluate the consequences on hippocampal neuronal networks of kindling stimulation versus electrode implantation. No overt modification of field potentials was detected in either the CA1 or the DG areas. In contrast, a very significant increase in the occurrence of repetitive population spikes evoked by single stimuli was detected in the CA3 area in slices from both amygdala kindled and non-stimulated amygdala implanted rats. The epileptiform pattern of CA3 field potentials was at least as well expressed in implanted non-stimulated, as in kindled rats, suggesting that electrode implantation has a major contribution to this marker of epileptogenesis.

Action Potentials↗
PubMed1993

Experience with 509 plate electrodes implanted epidurally from C1 to L1.

This article summarizes the experience gained with implantation of 509 plate electrodes performed by a single neurosurgeon. 350 patients were subjected to implantation of plate electrodes in the dorsal epidural space. 227 patients were implanted for chronic pain management (reflex sympathetic dystrophy, failed back syndrome/arachnoiditis, pain following spinal cord injury, nerve injury pain and other miscellaneous pain conditions), 105 patients for motor disorders (spasms/spasticity following spinal cord or head injury, cerebral palsy, multiple sclerosis, spasmodic torticollis and other miscellaneous conditions) and 18 patients for both. A total of 509 electrodes were implanted in the dorsal epidural space. The electrodes types were: 442 Medtronic Resume, 39 Medtronic Resume-TL and 25 Neuromed Lamitrode. 378 electrodes were implanted for chronic pain management, 106 for motor disorders and 25 in patients presenting with both pain and motor disorders. 192 electrodes were implanted in the cervical area and 317 in the thoracic area. 3.7% of the implanted electrodes became infected and had to be surgically removed. Electrode migration occurred in 1.1% of the patients and electrode breakage in 4 patients. 288 (70%) of the implanted electrodes are still being used. Technical factors relevant to the surgical implantation of plate electrodes at various levels in the spine are presented and discussed.

Adolescent↗
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↗
PubMed1987

A cross-referencing method for simultaneous slow and multiple unit potential recording with implanted electrodes.

The effective pairing of a non-polarizing Ag-AgCl with an adjacent polarizing stainless steel minielectrode for simultaneous recording of slow or sustained potentials, conventional ECoG, and multiple unit potentials is demonstrated. The two types of electrode reciprocate their reference functions, the non-polarizing electrode being insensitive to the low voltage 1500-2500 kHz signal transmitted by the polarizing member and the latter being insensitive to the slow potentials (0-0.5 Hz) detected by the non-polarizing member. The method enables obtaining unambiguous information from a localized source in bipolar derivations and permits use of construction methods simpler than those required for the hybrid electrodes formerly used.

Action Potentials↗