scholarly journals Modeling intracranial electrodes

2021 ◽  
Author(s):  
Alejandro Blenkmann ◽  
Anne-Kristin Solbakk ◽  
Jugoslav Ivanovic ◽  
Pål Gunnar Larsson ◽  
Robert T. Knight ◽  
...  
Keyword(s):  
Electrode Array ◽  
Localization Algorithm ◽  
Electrode Arrays ◽  
Implanted Electrodes ◽  
Brain Functions ◽  
Brain Surface ◽  
Depth Electrodes ◽  
Surgical Evaluation ◽  
Drug Resistant Epilepsy ◽  
Intracranial Electrodes

AbstractBackgroundIntracranial electrodes are implanted in patients with drug-resistant epilepsy as part of their pre-surgical evaluation. This allows investigation of normal and pathological brain functions with excellent spatial and temporal resolution. The spatial resolution relies on methods that precisely localize the implanted electrodes in the cerebral cortex, which is critical for drawing valid anatomical inferences about brain function.Multiple methods have been developed to localize implanted electrodes, mainly relying on pre-implantation MRI and post-implantation CT images. However, there is no standard approach to quantify the performance of these methods systematically.The purpose of our work is to model intracranial electrodes to simulate realistic implantation scenarios, thereby providing methods to optimize localization algorithm performance.ResultsWe implemented novel methods to model the coordinates of implanted grids, strips, and depth electrodes, as well as the CT artifacts produced by these.We successfully modeled a large number of realistic implantation “scenarios”, including different sizes, inter-electrode distances, and brain areas. In total, more than 3300 grids and strips were fitted over the brain surface, and more than 850 depth electrode arrays penetrating the cortical tissue were modeled. More than 37000 simulations of electrode array CT artifacts were performed in these “scenarios”, mimicking the intensity profile and orientation of real artifactual voxels. Realistic artifacts were simulated by introducing different noise levels, as well as overlapping electrodes.ConclusionsWe successfully developed the first platform to model implanted intracranial grids, strips, and depth electrodes and realistically simulate CT artifacts and noise.These methods set the basis for developing more complex models, while simulations allow the performance evaluation of electrode localization techniques systematically.The methods described in this article, and the results obtained from the simulations, are freely available via open repositories. A graphical user interface implementation is also accessible via the open-source iElectrodes toolbox.

scholarly journals Orientation of Temporal Interference for Non-Invasive Deep Brain Stimulation in Epilepsy

2020 ◽  
Author(s):  
Florian Missey ◽  
Evgeniia Rusina ◽  
Emma Acerbo ◽  
Boris Botzanowski ◽  
Romain Carron ◽  
...  
Keyword(s):  
Electric Fields ◽  
Brain Regions ◽  
Intracranial Stimulation ◽  
Epileptogenic Zone ◽  
Implanted Electrodes ◽  
Non Invasive ◽  
Gamma Range ◽  
Wide Range ◽  
Drug Resistant Epilepsy ◽  
Intracranial Electrodes

AbstractIn patients with focal drug-resistant epilepsy, electrical stimulation from intracranial electrodes is frequently used for the localization of seizure onset zones and related pathological networks. The ability of electrically stimulated tissue to generate beta and gamma range oscillations, called rapid-discharges, is a frequent indication of an epileptogenic zone. However, a limit of intracranial stimulation is the fixed physical location and number of implanted electrodes, leaving numerous clinically and functionally relevant brain regions unexplored. Here, we demonstrate an alternative technique relying exclusively on nonpenetrating surface electrodes, namely an orientation-tunable form of temporally-interfering (TI) electric fields to target the CA3 of the mouse hippocampus which focally evokes seizure-like events (SLEs) having the characteristic frequencies of rapid-discharges, but without the necessity of the implanted electrodes. The orientation of the topical electrodes with respect to the orientation of the hippocampus is demonstrated to strongly control the threshold for evoking SLEs. Additionally, we demonstrate the use of square waves as an alternative to sine waves for TI stimulation. An orientation-dependent analysis of classic implanted electrodes to evoke SLEs in the hippocampus is subsequently utilized to support the results of the minimally-invasive temporally-interfering fields. The principles of orientation-tunable TI stimulation seen here can be generally applicable in a wide range of other excitable tissues and brain regions, overcoming several limitations of fixed electrodes which penetrate tissue.

Technical and Practical Aspects of Invasive Recordings and Brain Stimulation

2018 ◽  
pp. 26-37
Author(s):  
Gholam K. Motamedi ◽  
Jean Gotman ◽  
Ronald P. Lesser
Keyword(s):  
Charge Density ◽  
Surface Area ◽  
Brain Stimulation ◽  
Electrode Surface ◽  
Cortical Stimulation ◽  
Basic Principles ◽  
Depth Electrodes ◽  
Cortical Stimulation Mapping ◽  
Drug Resistant Epilepsy ◽  
Intracranial Electrodes

This chapter discusses the technical and practical issues involved in invasive recording and cortical stimulation mapping in patients with drug-resistant epilepsy. It reviews the way in which EEG signals are generated, circumstances when intracranial electrodes are needed, and how such electrodes operate. It also discusses the basic principles of cortical stimulation mapping and different methods of using intracranial electrodes for stimulation purposes, and relevant concepts involved in the process such as charge density and electrode surface area. It reviews different electrodes used for mapping including subdural surface electrodes and depth electrodes.

scholarly journals Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Dong-Wook Park ◽  
Amelia A. Schendel ◽  
Solomon Mikael ◽  
Sarah K. Brodnick ◽  
Thomas J. Richner ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Electrode Array ◽  
Electrode Arrays ◽  
Neural Imaging ◽  
Brain Surface ◽  
Array Technology ◽  
Micro Electrode Arrays ◽  
The Brain

Abstract Neural micro-electrode arrays that are transparent over a broad wavelength spectrum from ultraviolet to infrared could allow for simultaneous electrophysiology and optical imaging, as well as optogenetic modulation of the underlying brain tissue. The long-term biocompatibility and reliability of neural micro-electrodes also require their mechanical flexibility and compliance with soft tissues. Here we present a graphene-based, carbon-layered electrode array (CLEAR) device, which can be implanted on the brain surface in rodents for high-resolution neurophysiological recording. We characterize optical transparency of the device at >90% transmission over the ultraviolet to infrared spectrum and demonstrate its utility through optical interface experiments that use this broad spectrum transparency. These include optogenetic activation of focal cortical areas directly beneath electrodes, in vivo imaging of the cortical vasculature via fluorescence microscopy and 3D optical coherence tomography. This study demonstrates an array of interfacing abilities of the CLEAR device and its utility for neural applications.

scholarly journals Single-Institutional Experience of Chronic Intracranial Electroencephalography Based on the Combined Usage of Subdural and Depth Electrodes

2021 ◽  
Vol 11 (3) ◽  
pp. 307
Author(s):  
Yutaro Takayama ◽  
Naoki Ikegaya ◽  
Keiya Iijima ◽  
Yuiko Kimura ◽  
Suguru Yokosako ◽  
...  
Keyword(s):  
Intractable Epilepsy ◽  
Seizure Freedom ◽  
Brain Surface ◽  
Depth Electrodes ◽  
Significant Difference ◽  
Institutional Experience ◽  
Temporal Structures ◽  
Drug Resistant Epilepsy ◽  
Intracranial Electroencephalography ◽  
The Brain

Implantation of subdural electrodes on the brain surface is still widely performed as one of the “gold standard methods” for the presurgical evaluation of epilepsy. Stereotactic insertion of depth electrodes to the brain can be added to detect brain activities in deep-seated lesions to which surface electrodes are insensitive. This study tried to clarify the efficacy and limitations of combined implantation of subdural and depth electrodes in intractable epilepsy patients. Fifty-three patients with drug-resistant epilepsy underwent combined implantation of subdural and depth electrodes for long-term intracranial electroencephalography (iEEG) before epilepsy surgery. The detectability of early ictal iEEG change (EIIC) were compared between the subdural and depth electrodes. We also examined clinical factors including resection of MRI lesion and EIIC with seizure freedom. Detectability of EIIC showed no significant difference between subdural and depth electrodes. However, the additional depth electrode was useful for detecting EIIC from apparently deep locations, such as the insula and mesial temporal structures, but not in detecting EIIC in patients with ulegyria (glial scar). Total removal of MRI lesion was associated with seizure freedom. Depth electrodes should be carefully used after consideration of the suspected etiology to avoid injudicious usage.

Mapping of sensory responses to epidural stimulation of the intraspinal neural structures in man

1993 ◽  
Vol 78 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Giancarlo Barolat ◽  
Fulvio Massaro ◽  
Jiping He ◽  
Sergio Zeme ◽  
Beth Ketcik
Keyword(s):  
Electrode Array ◽  
Electrode Arrays ◽  
Content Type ◽  
Implanted Electrodes ◽  
Root Entry Zone ◽  
Dorsal Columns ◽  
Epidural Spinal Cord Stimulation ◽  
Sensory Responses ◽  
Stimulation Of

✓ A database is presented of sensory responses to electrical stimulation of the dorsal neural structures at various spine levels in 106 subjects subjected to epidural spinal cord stimulation. All patients were implanted for chronic pain management and were able to perceive stimulation in the area of pain. All patients entered in this study were able to reliably report their stimulation pattern. Several patients were implanted with more than one electrode array. The electrode arrays were placed in the dorsal epidural space at levels between C-1 and L-1. The structures that were likely involved include the dorsal roots, dorsal root entry zone, dorsal horn, and dorsal columns. At the present time, exact characterization of the structure being stimulated is possible only in limited instances. Various body areas are presented with the correspondent spine levels where implanted electrodes generate paresthesias. Areas that are relatively easy targets for stimulation are the median aspect of the hand, the abdominal wall, the anterior aspect of the thigh, and the foot. Some areas are particularly difficult to cover with stimulation-induced paresthesias; these include the C-2 distribution, the neck, the low back, and the perineum.

scholarly journals The Importance of Intraoperative Plain Radiographs during Cochlear Implant Surgery in Patients with Normal Anatomy

2021 ◽  
Vol 11 (9) ◽  
pp. 4144
Author(s):  
Ohad Cohen ◽  
Jean-Yves Sichel ◽  
Chanan Shaul ◽  
Itay Chen ◽  
J. Thomas Roland ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Cost Effective ◽  
X Rays ◽  
Normal Anatomy ◽  
Electrode Arrays ◽  
Plain Radiographs ◽  
Hearing Function ◽  
Tertiary Center ◽  
Cochlear Implant Surgery

Although malpositioning of the cochlear implant (CI) electrode array is rare in patients with normal anatomy, when occurring it may result in reduced hearing outcome. In addition to intraoperative electrophysiologic tests, imaging is an important modality to assess correct electrode array placement. The purpose of this report was to assess the incidence and describe cases in which intraoperative plain radiographs detected a malpositioned array. Intraoperative anti-Stenver’s view plain X-rays are conducted routinely in all CI surgeries in our tertiary center before awakening the patient and breaking the sterile field. Data of patients undergoing 399 CI surgeries were retrospectively analyzed. A total of 355 had normal inner ear and temporal bone anatomy. Patients with intra or extracochlear malpositioned electrode arrays demonstrated in the intraoperative X-ray were described. There were four cases of electrode array malposition out of 355 implantations with normal anatomy (1.1%): two tip fold-overs, one extracochlear placement and one partial insertion. All electrodes were reinserted immediately; repeated radiographs were normal and the patients achieved good hearing function. Intraoperative plain anti-Stenver’s view X-rays are valuable to confirm electrode array location, allowing correction before the conclusion of surgery. These radiographs are cheaper, faster, and emit much less radiation than other imaging options, making them a viable cost-effective tool in patients with normal anatomy.

scholarly journals Medically resistant pediatric insular-opercular/perisylvian epilepsy. Part 1: invasive monitoring using the parasagittal transinsular apex depth electrode

2016 ◽  
Vol 18 (5) ◽  
pp. 511-522 ◽  
Author(s):  
Alexander G. Weil ◽  
Aria Fallah ◽  
Evan C. Lewis ◽  
Sanjiv Bhatia
Keyword(s):  
Epilepsy Surgery ◽  
Electrode Placement ◽  
Epileptogenic Zone ◽  
Drug Resistant ◽  
Depth Electrodes ◽  
Depth Electrode ◽  
Age At Surgery ◽  
Feasible Alternative ◽  
The Mean ◽  
Drug Resistant Epilepsy

OBJECTIVE Insular lobe epilepsy (ILE) is an under-recognized cause of extratemporal epilepsy and explains some epilepsy surgery failures in children with drug-resistant epilepsy. The diagnosis of ILE usually requires invasive investigation with insular sampling; however, the location of the insula below the opercula and the dense middle cerebral artery vasculature renders its sampling challenging. Several techniques have been described, ranging from open direct placement of orthogonal subpial depth and strip electrodes through a craniotomy to frame-based stereotactic placement of orthogonal or oblique electrodes using stereo-electroencephalography principles. The authors describe an alternative method for sampling the insula, which involves placing insular depth electrodes along the long axis of the insula through the insular apex following dissection of the sylvian fissure in conjunction with subdural electrodes over the lateral hemispheric/opercular region. The authors report the feasibility, advantages, disadvantages, and role of this approach in investigating pediatric insular-opercular refractory epilepsy. METHODS The authors performed a retrospective analysis of all children (< 18 years old) who underwent invasive intracranial studies involving the insula between 2002 and 2015. RESULTS Eleven patients were included in the study (5 boys). The mean age at surgery was 7.6 years (range 0.5–16 years). All patients had drug-resistant epilepsy as defined by the International League Against Epilepsy and underwent comprehensive noninvasive epilepsy surgery workup. Intracranial monitoring was performed in all patients using 1 parasagittal insular electrode (1 patient had 2 electrodes) in addition to subdural grids and strips tailored to the suspected epileptogenic zone. In 10 patients, extraoperative monitoring was used; in 1 patient, intraoperative electrocorticography was used alone without extraoperative monitoring. The mean number of insular contacts was 6.8 (range 4–8), and the mean number of fronto-parieto-temporal hemispheric contacts was 61.7 (range 40–92). There were no complications related to placement of these depth electrodes. All 11 patients underwent subsequent resective surgery involving the insula. CONCLUSIONS Parasagittal transinsular apex depth electrode placement is a feasible alternative to orthogonally placed open or oblique-placed stereotactic methodologies. This method is safe and best suited for suspected unilateral cases with a possible extensive insular-opercular epileptogenic zone.

Precise Alignment of Micromachined Electrode Arrays With V1 Functional Maps

2007 ◽  
Vol 97 (5) ◽  
pp. 3781-3789 ◽  
Author(s):  
Ian Nauhaus ◽  
Dario L. Ringach
Keyword(s):  
Receptive Field ◽  
Electrode Array ◽  
Theoretical Models ◽  
Orientation Tuning ◽  
Feedback Signal ◽  
Electrode Arrays ◽  
Tuning Curves ◽  
Alignment Procedure ◽  
Receptive Field Properties ◽  
Orientation Maps

Recent theoretical models of primary visual cortex predict a relationship between receptive field properties and the location of the neuron within the orientation maps. Testing these predictions requires the development of new methods that allow the recording of single units at various locations across the orientation map. Here we present a novel technique for the precise alignment of functional maps and array recordings. Our strategy consists of first measuring the orientation maps in V1 using intrinsic optical imaging. A micromachined electrode array is subsequently implanted in the same patch of cortex for electrophysiological recordings, including the measurement of orientation tuning curves. The location of the array within the map is obtained by finding the position that maximizes the agreement between the preferred orientations measured electrically and optically. Experimental results of the alignment procedure from two implementations in monkey V1 are presented. The estimated accuracy of the procedure is evaluated using computer simulations. The methodology should prove useful in studying how signals from the local neighborhood of a neuron, thought to provide a dominant feedback signal, shape the receptive field properties in V1.

scholarly journals Design and development of a multichannel potentiometer for monitoring an electrode array and its application in flow analysis

2002 ◽  
Vol 24 (4) ◽  
pp. 105-110 ◽  
Author(s):  
Jarbas J. R. Rohwedder ◽  
Celio Pasquini ◽  
Ivo M. Raimundo, Jr. ◽  
M. Conceiçao ◽  
B. S. M. Montenegro ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Flow Analysis ◽  
Reference Electrode ◽  
Electrode Array ◽  
Ion Selective Electrodes ◽  
Electrode Arrays ◽  
Figures Of Merit ◽  
Flow Through ◽  
The Individual ◽  
Intense Signal

A versatile potentiometer that works with electrode arrays in flow injection and/or monosegmented flow systems is described. The potentiometer is controlled by a microcomputer that allows individual, sequential multiplexed or random accesses to eight electrodes while employing only one reference electrode. The instrument was demonstrated by monitoring an array of seven flow-through ion-selective electrodes for Ag+and for three electrodes for Cl-, Ca2+and K+. The figures of merit of the individual and multiplexed (summed) readings of the electrode array were compared. The absolute standard deviation of the measurements made by summing the potential of two or more electrodes was maintained constant, thus improving the precision of the measurements. This result shows that an attempt to combine the signals of the electrodes to produce a more intense signal in the Hadamard strategy is feasible and accompanied by a proportional improvement in the precision of individual measurements. The preliminary tests suggest that the system can allow for 270 determinations per hour, with a linear range from1.0×10−2to1.0×10−4mol l-1for the three di¡erent analytes. Detection limits were estimated as3.1×10−5,3.0×10−6and1.0×10−5mol l-1for Cl-, Ca2+and K+, respectively.

Stereoencephalography Electrode Placement Accuracy and Utility Using a Frameless Insertion Platform Without a Rigid Cannula

2019 ◽  
Author(s):  
Erin D’Agostino ◽  
John Kanter ◽  
Yinchen Song ◽  
Joshua P Aronson
Keyword(s):  
Electrode Placement ◽  
Target Point ◽  
Localization Error ◽  
Drug Resistant ◽  
Guide Cannula ◽  
Lateral Entry ◽  
Accurate Localization ◽  
Depth Electrodes ◽  
Rigid Frame ◽  
Drug Resistant Epilepsy

Abstract BACKGROUND Implantation of depth electrodes to localize epileptogenic foci in patients with drug-resistant epilepsy can be accomplished using traditional rigid frame-based, custom frameless, and robotic stereotactic systems. OBJECTIVE To evaluate the accuracy of electrode implantation using the FHC microTargeting platform, a custom frameless platform, without a rigid insertion cannula. METHODS A total of 182 depth electrodes were implanted in 13 consecutive patients who underwent stereoelectroencephalography (SEEG) for drug-resistant epilepsy using the microTargeting platform and depth electrodes without a rigid guide cannula. MATLAB was utilized to evaluate targeting accuracy. Three manual coordinate measurements with high inter-rater reliability were averaged. RESULTS Patients were predominantly male (77%) with average age 35.62 (SD 11.0, range 21-57) and average age of epilepsy onset at 13.4 (SD 7.2, range 3-26). A mean of 14 electrodes were implanted (range 10-18). Mean operative time was 144 min (range 104-176). Implantation of 3 out of 182 electrodes resulted in nonoperative hemorrhage (2 small subdural hematomas and one small subarachnoid hemorrhage). Putative location of onset was identified in all patients. We demonstrated a median lateral target point localization error (LTPLE) of 3.95 mm (IQR 2.18-6.23), a lateral entry point localization error (LEPLE) of 1.98 mm (IQR 1.2-2.85), a target depth error of 1.71 mm (IQR 1.03-2.33), and total target point localization error (TPLE) of 4.95 mm (IQR 2.98-6.85). CONCLUSION Utilization of the FHC microTargeting platform without the use of insertion cannulae is safe, effective, and accurate. Localization of seizure foci was accomplished in all patients and accuracy of depth electrode placement was satisfactory.

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