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Electrode Placement (electrode + placement)
Selected AbstractsFocal electroporation in ovoDEVELOPMENTAL DYNAMICS, Issue 12 2009J. E. Simkin Abstract Gene expression fields in embryogenesis are spatially precise and often small, so experimental gene expression often requires similar spatial definition. For in ovo electroporation, typically a gene construct is injected into a natural body cavity in the embryo prior to electroporation. Limited control of the size and location of the electroporated field can be obtained by varying electrode placement and geometry, and by altering the miscibility and viscosity of the construct vehicle but it is difficult to tightly constrain electroporation to small regions. Electroporation of different constructs in close proximity has not been possible. We show that loading the construct into an agarose bead, which is then microsurgically implanted, allows for focal electroporation. Different constructs can be electroporated in close proximity by emplacing several agarose beads. This technique is simple, cheap, rapid, and requires no more specialised equipment than that required for conventional in ovo electroporation. Developmental Dynamics 238:3152,3155, 2009. © 2009 Wiley-Liss, Inc. [source] Seizures Lead to Elevation of Intracranial Pressure in Children Undergoing Invasive EEG MonitoringEPILEPSIA, Issue 6 2007Aash K Shah Summary:,Purpose: To study the effects of intracranial subdural grid electrode placement and seizures on intracranial pressure (ICP) in children undergoing invasive EEG monitoring. Methods: Sixteen children with pharmacoresistant epilepsy who underwent two-stage epilepsy surgery with subdural grid placement were included in the study. The ICP was recorded at baseline and with each seizure prospectively. A variety of seizure parameters including type of seizure, length of seizure, extent of seizure spread, and number of subdural grid electrodes inserted were analyzed retrospectively and correlated with the change in ICP. Results: A total of 48 seizures in 16 children were studied. The mean baseline ICP correlated positively with age of the child. Generalized tonic,clonic seizures were associated with the highest rise in ICP. Similarly, ICP rise was associated with seizures involving more electrodes indicating a larger area of brain participating in the seizure. Conclusion: Seizures in general and generalized tonic,clonic seizures, in particular, increase ICP temporarily in patients who are undergoing invasive EEG monitoring with subdural grids. [source] Activity and energetics of free-swimming fish: insights from electromyogram telemetryFISH AND FISHERIES, Issue 1 2004Steven J Cooke Abstract Electromyogram (EMG) telemetry studies that involve remotely monitoring the locomotory activity and energetics of fish are contributing important information to the conservation and management of fisheries resources. Here, we outline the development of this rapidly evolving field and formulate the studies conducted that utilize this technology. To date, more than 60 studies have been conducted using EMG telemetry that spans 18 species. Several general trends were observed in the methodology of the studies that we have highlighted as standards that should be adopted associated with transmitter customization, electrode placement and surgical technique. Although numerous studies have been methodological, there are still some deficiencies in our basic understanding of issues such as the need for individual calibration and the method of reporting or transforming data. Increasingly, this technology is being applied to address issues in conservation, management and aquaculture production. At present, the technology has been most frequently applied to the study of animal activity or energetics and to migration. Several recent studies have also focused on addressing more basic questions in ecological and evolutionary biology (e.g. parental care dynamics) similar to the large body of literature that has been collected for other taxa (e.g. marine mammals, birds), using activity telemetry. Collectively, studies conducted using EMG telemetry have contributed important information on free-swimming fish that was previously difficult to obtain. EMG telemetry is particularly effective for examining behaviour at temporal and spatial scales that are difficult using other techniques. The development of an ultrasonic transmitter based on the same proven principles as those used in the current radio transmitter technology will permit studies in other environments (i.e. marine, brackish, deep water) and on different species of fish. We encourage the continued development and refinement of devices for monitoring the activity and energetics of free-swimming fish, and also encourage researchers to consider EMG telemetry as a tool for addressing questions that are not effectively answered with other techniques. [source] Use of a Single Coil Transvenous Electrode with an Abdominally Placed Implantable Cardioverter Defibrillator in ChildrenPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2000PETER S. FISCHBACH While transvenous defibrillator electrode placement avoiding a thoracotomy is preferable, electrode size, a large intercoil spacing, and the need for subclavicular device placement preclude this approach in most children. We investigated a single RV coil to an abdominally placed active can ICD device. Five children ages 8,16 years (weight 21,50 kg, mean 35 kg) underwent ICD placement. Placement of a single coil Medtronic model 6932 or 6943 electrode was performed via the left subclavian vein approach and the electrode positioned in the RV apex with the coil lying along the RV diaphragmatic surface. The ICD (Medtronic Micro Jewel II model 7223Cx) was implanted in a left abdominal pocket with the lead tunneled from the infraclavicular region to the pocket. Implant DFTs were ± 15 J using a biphasic waveform. DFTs rechecked within 3-month postimplant were unchanged. Lead impedance at implant ranged from 38 to 56 ,, mean 51 ,. Follow-up was 3,21 months (total 82 months) with no electrode dislodgment. lead fractures, or inappropriate discharges. Two of the five patients have had successful appropriate ICD discharges. Transvenous ICD electrode placement can be performed in children as small as 20 kg with the device implanted in a cosmetically acceptable abdominal pocket that is well tolerated. Excellent DFTs can be achieved. This approach avoids a thoracotomy in all but the smallest child, does not require subclavicular placement of the device, and avoids use of a second intravascular coil. [source] Anatomy of the Middle-Turn Cochleostomy,THE LARYNGOSCOPE, Issue 12 2008Brandon Isaacson MD Abstract Objective: Middle-turn cochleostomies are occasionally used for cochlear implant electrode placement in patients with labyrinthitis ossificans. This study evaluates the anatomic characteristics of the middle-turn cochleostomy and its suitability for placement of implant electrodes. Methods: Ten cadaveric human temporal bones were dissected using a facial recess approach. A middle-turn cochleostomy was drilled 2 mm anterior to the oval window and just inferior to the cochleariform process. The preparations were then stained with osmium tetroxide and microdissections were performed. The location of the cochleostomy on the cochlear spiral and its path through the various cochlear compartments were evaluated in all 10 specimens. A Cochlear Corporation depth gauge was inserted in five of the specimens and insertion trauma, number of contact rings, and depth of insertion were recorded. Results: Eight of the 10 cochleostomies were placed at approximately 360° on the cochlear spiral, near the transition between the basal and middle turns. In one case, the cochleostomy was found to enter the cochlear apex and in another it entered scala vestibuli of the proximal basal turn. The cochleostomy entered scala media in six bones and scala vestibuli in four specimens. A depth gauge was inserted in five specimens. The number of contacts placed within the cochlear lumen ranged from four to nine. There was evidence of insertional trauma to the lateral wall of the cochlear duct, basilar membrane, and Reissner's membrane, but no evidence of fractures to the osseous spiral lamina or modiolus. Conclusion: This study demonstrates that electrodes inserted via a middle-turn cochleostomy are likely to enter scala vestibuli and have access to the middle- and apical-cochlear turns. It is also possible that the electrode could be directed into the descending portion of the basal turn depending on cochleostomy orientation. Middle-turn cochleostomy seems to be a viable alternative for electrode placement when preservation of residual hearing is not a concern. [source] Effect of epilepsy magnetic source imaging on intracranial electrode placement,ANNALS OF NEUROLOGY, Issue 6 2009MSPH, Robert C. Knowlton MD Objective Intracranial electroencephalography (ICEEG) with chronically implanted electrodes is a costly invasive diagnostic procedure that remains necessary for a large proportion of patients who undergo evaluation for epilepsy surgery. This study was designed to evaluate whether magnetic source imaging (MSI), a noninvasive test based on magnetoencephalography source localization, can supplement ICEEG by affecting electrode placement to improve sampling of the seizure onset zone(s). Methods Of 298 consecutive epilepsy surgery candidates (between 2001 and 2006), 160 patients were prospectively enrolled by insufficient localization from seizure monitoring and magnetic resonance imaging results. Before presenting MSI results, decisions were made whether to proceed with ICEEG, and if so, where to place electrodes such that the hypothetical seizure-onset zone would be sampled. MSI results were then provided with allowance of changes to the original plan. Results MSI indicated additional electrode coverage in 18 of 77 (23%) ICEEG cases. In 39% (95% confidence interval, 16.4,61.4), seizure-onset ICEEG patterns involved the additional electrodes indicated by MSI. Sixty-two patients underwent surgical resection based on ICEEG recording of seizures. Highly localized MSI was significantly associated with seizure-free outcome (mean, 3.4 years; minimum, >1 year) for the entire surgical population (n = 62). Interpretation MSI spike localization increases the chance that the seizure-onset zone is sampled when patients undergo ICEEG for presurgical epilepsy evaluations. The clinical impact of this effect, improving diagnostic yield of ICEEG, should be considered in surgery candidates who do not have satisfactory indication of epilepsy localization from seizure semiology, electroencephalogram, and magnetic resonance imaging. Ann Neurol 2009;65:716,723 [source] WT1 Is Not a Reliable Marker to Distinguish Reactive from Neoplastic Astrocyte Populations in the Central Nervous SystemBRAIN PATHOLOGY, Issue 6 2010T. David Bourne MD Abstract A diagnostic difficulty in neuropathology practice is distinguishing reactive from neoplastic astrocyte populations. This is particularly true in small biopsy samples that lack evidence of increased cellularity or mitotic activity, microvascular proliferation, or necrosis. We performed the current study to validate the previously reported finding that in the central nervous system, the expression of WT1 is limited to neoplastic astrocytes. We retrospectively studied WT1 protein expression by immunohistochemistry (IHC) in 100 formalin-fixed, paraffin-embedded brain tissue samples consisting of 3 normal control tissues, 44 cases of reactive gliosis, 49 gliomas and 4 lesions suspicious for glioma. In normal human cortex, WT1 staining was restricted to vascular endothelium. Most cases of reactive gliosis (82%) showed at least focal WT1 positivity, and analysis of specimens with electrode monitoring lesions showed an inverse relationship between WT1 expression intensity and the number of days from electrode placement to tissue resection. All glioma samples (100%) and all cases suspicious for glioma (100%) showed at least focal WT1 positivity. Our results likely differ from those in the prior report because of differences in tissue fixation and IHC methodology. Thus, our findings indicate that WT1 expression alone is not a reliable feature to distinguish reactive from neoplastic astrocytes. [source] Would Different Routine Precordial Electrode Positions Be More Useful?CLINICAL CARDIOLOGY, Issue 2 2009Answer: Not Likely Abstract There are reasons to wonder if the current precordial electrode positions are the best ones to study the electrical forces of the heart. Theoretically, more horizontal electrode positions and several superior and inferior electrode positions that are perpendicular to the horizontally placed electrode positions should make a superior lead system. A study was designed to determine if that was true. The result of the study indicated that such a system did not solve all of the problems that were posed by the current system. Although the new system was easier to use, the findings did not justify a change from the presently used system of precordial electrode placement. Copyright © 2009 Wiley Periodicals, Inc. [source] Electroconvulsive therapy is equally effective in unipolar and bipolar depressionACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2010S. Bailine Bailine S, Fink M, Knapp R, Petrides G, Husain MM, Rasmussen K, Sampson S, Mueller M, McClintock SM, Tobias KG, Kellner CH. Electroconvulsive therapy is equally effective in unipolar and bipolar depression. Objective:, To determine the relative efficacy of electroconvulsive therapy (ECT) in the treatment of bipolar (BP) and unipolar (UP) depressive illness and clarify its role in BP depression. Method:, Patients referred for ECT with both UP and BP depressions. [classified by Structured Clinical Interview for DSM (SCID-I) criteria for history of mania] were included in a multi-site collaborative, double-masked, randomized controlled trial of three electrode placements , right unilateral, bifrontal or bitemporal , in a permutated block randomization scheme. Results:, Of 220 patients, 170 patients (77.3%) were classified as UP and 50 (22.7%) as BP depression in the intent-to-treat sample. The remission and response rates and numbers of ECT for both groups were equivalent. Conclusion:, Both UP and BP depressions remit with ECT. Polarity is not a factor in the response rate. In this sample ECT did not precipitate mania in depressed patients. Treatment algorithms for UP and BP depression warrant re-evaluation. [source] | ||||||||||||||||||||||