Early seizure spread and epilepsy surgery: A systematic review

Andrews, John P.; Ammanuel, Simon; Kleen, Jonathan K.; Khambhati, Ankit N.; Knowlton, Robert C.; Chang, Edward F.

doi:10.1111/epi.16668

Cited by 13 publications

(12 citation statements)

References 54 publications

(120 reference statements)

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“…These findings align with a previously proposed indirect mechanism of RNS (58) whereby stimulation slowly disrupts the seizure-producing epileptogenic network core (59), which breaks apart into discrete neuronal populations that are unable to synchronize sufficiently to generate a seizure (17,60). We speculate that a "spark-on-kindling" model-in which elevated network synchrony is the kindling upon which IEA might spark a fire (seizure)may explain our empirical observation (61). A plasticity-based mechanism of effective therapy predicts that interictal stimulation progressively desynchronizes the epileptogenic network, which serves more poorly as kindling and is less vulnerable to input from IEA.…”

Section: Discussionsupporting

confidence: 91%

Long-term brain network reorganization predicts responsive neurostimulation outcomes for focal epilepsy

et al. 2021

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Responsive neurostimulation (RNS) devices, able to detect imminent seizures and to rapidly deliver electrical stimulation to the brain, are effective in reducing seizures in some patients with focal epilepsy. However, therapeutic response to RNS is often slow, is highly variable, and defies prognostication based on clinical factors. A prevailing view holds that RNS efficacy is primarily mediated by acute seizure termination; yet, stimulations greatly outnumber seizures and occur mostly in the interictal state, suggesting chronic modulation of brain networks that generate seizures. Here, using years-long intracranial neural recordings collected during RNS therapy, we found that patients with the greatest therapeutic benefit undergo progressive, frequency-dependent reorganization of interictal functional connectivity. The extent of this reorganization scales directly with seizure reduction and emerges within the first year of RNS treatment, enabling potential early prediction of therapeutic response. Our findings reveal a mechanism for RNS that involves network plasticity and may inform development of next-generation devices for epilepsy.

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Section: Discussionsupporting

confidence: 91%

Long-term brain network reorganization predicts responsive neurostimulation outcomes for focal epilepsy

et al. 2021

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“…Such methods also provide an intuitive visualization of subsequent spatial spread patterns of seizures (Figure 4), which can further inform resective surgical planning and/or placement of electrodes for responsive neurostimulation 39 . Finally, cinematic visualization helps illustrate the speed of the ictal wavefront across deep and superficial structures, and the spatial extent of regional ictal onsets, predictive factors for surgical outcome 11,28–31 . This preliminary validation study is encouraging for the use of omni‐planar ICEEG seizure visualization as an adjunct for ICEEG interpretation and surgical planning, and as a communication tool among healthcare providers and trainees at all levels.…”

Section: Discussionmentioning

confidence: 89%

Accuracy of omni‐planar and surface casting of epileptiform activity for intracranial seizure localization

et al. 2021

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Summary Objective Intracranial electroencephalography (ICEEG) recordings are performed for seizure localization in medically refractory epilepsy. Signal quantifications such as frequency power can be projected as heatmaps on personalized three‐dimensional (3D) reconstructed cortical surfaces to distill these complex recordings into intuitive cinematic visualizations. However, simultaneously reconciling deep recording locations and reliably tracking evolving ictal patterns remain significant challenges. Methods We fused oblique magnetic resonance imaging (MRI) slices along depth probe trajectories with cortical surface reconstructions and projected dynamic heatmaps using a simple mathematical metric of epileptiform activity (line‐length). This omni‐planar and surface casting of epileptiform activity approach (OPSCEA) thus illustrated seizure onset and spread among both deep and superficial locations simultaneously with minimal need for signal processing supervision. We utilized the approach on 41 patients at our center implanted with grid, strip, and/or depth electrodes for localizing medically refractory seizures. Peri‐ictal data were converted into OPSCEA videos with multiple 3D brain views illustrating all electrode locations. Five people of varying expertise in epilepsy (medical student through epilepsy attending level) attempted to localize the seizure‐onset zones. Results We retrospectively compared this approach with the original ICEEG study reports for validation. Accuracy ranged from 73.2% to 97.6% for complete or overlapping onset lobe(s), respectively, and ~56.1% to 95.1% for the specific focus (or foci). Higher answer certainty for a given case predicted better accuracy, and scorers had similar accuracy across different training levels. Significance In an era of increasing stereo‐EEG use, cinematic visualizations fusing omni‐planar and surface functional projections appear to provide a useful adjunct for interpreting complex intracranial recordings and subsequent surgery planning.

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“…The mechanical profiles of these materials, including elastic modulus and viscoelasticity, can be quite distinct from biological tissues (Figure 3). It is important that the substrate has a low bending stiffness, a metric dependent on the material mechanical modulus, ≈E, and thickness (≈t 3 ), while still being easy to precisely place at various locations.…”

Section: Substratementioning

confidence: 99%

“…Clinical electrocorticogram (ECoG) is used to identify similar functional changes on the cortical surface of the brain, most commonly to identify epileptic focal center(s), or detect seizure activity. [3][4][5][6][7] Other functional uses of ECoG include intraoperative monitoring during tumor resection. [8] A surgeon can ask a patient to perform an activity such as a speech and then identify and avoid the active cortical regions during surgery, to avoid major disruptions to the patient quality of life.…”

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confidence: 99%

Materials for Implantable Surface Electrode Arrays: Current Status and Future Directions

Tringides

Mooney

2022

Advanced Materials

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with the outermost layer of biological tissues, often spanning a significant surface area. Devices typically have multiple electrodes that aim to monitor and modulate cells and tissues in a minimally invasive manner, using biomaterials designed to evoke minimal inflammatory responses. Applications of Surface Electrode Arrays RecordingBecause surface electrode arrays can record a "snapshot" of the electrical activity at distinct locations, these arrays are useful to monitor the function of a tissue. Though the recordings are typically local field potentials, with electrodes that are small enough to modulate as little of a location as possible while still maintaining a sufficiently high conductivity, single units from individual cells have been reported. Clinically, these recordings are used to map the epicardial surface to identify instances, and potentially mechanisms, of chronic atrial fibrillation, [1] dysfunction of ventricular tachycardia caused by congenital defects, [2] and other abnormal conduction conditions in the cardiac system. Clinical electrocorticogram (ECoG) is used to identify similar functional changes on the cortical surface of the brain, most commonly to identify epileptic focal center(s), or detect seizure activity. [3][4][5][6][7] Other functional uses of ECoG include intraoperative monitoring during tumor resection. [8] A surgeon can ask a patient to perform an activity such as a speech and then identify and avoid the active cortical regions during surgery, to avoid major disruptions to the patient quality of life. StimulationInstead of passively monitoring electrical activity, multielectrode surface arrays can provide electrical current to the underlying tissue and induce a desired excitatory or inhibitory response. The applications for stimulating surface electrode arrays are often therapeutic and include implantable pacemakers, which restore a normal cardiac rhythm by providing external and overriding cues to the cardiomyocytes responsible for establishing a sinus rhythm. [9] Pulses delivered to specific regions of the spinal cord are used to manage chronic pain, [10][11][12] and more recently as a therapy to promote neuronal plasticity in Surface electrode arrays are mainly fabricated from rigid or elastic materials, and precisely manipulated ductile metal films, which offer limited stretchability. However, the living tissues to which they are applied are nonlinear viscoelastic materials, which can undergo significant mechanical deformation in dynamic biological environments. Further, the same arrays and compositions are often repurposed for vastly different tissues rather than optimizing the materials and mechanical properties of the implant for the target application. By first characterizing the desired biological environment, and then designing a technology for a particular organ, surface electrode arrays may be more conformable, and offer better interfaces to tissues while causing less damage. Here, the various materials used in each component of a surface electrode array are first r...

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Early seizure spread and epilepsy surgery: A systematic review

Cited by 13 publications

References 54 publications

Long-term brain network reorganization predicts responsive neurostimulation outcomes for focal epilepsy

Long-term brain network reorganization predicts responsive neurostimulation outcomes for focal epilepsy

Accuracy of omni‐planar and surface casting of epileptiform activity for intracranial seizure localization

Materials for Implantable Surface Electrode Arrays: Current Status and Future Directions

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