Phenomenological network models: Lessons for epilepsy surgery

Hebbink, Jurgen; Meijer, Hil Gaétan Ellart; Huiskamp, Geertjan; Gils, Stephan A. van; Leijten, Frans S.S.

doi:10.1111/epi.13861

Cited by 41 publications

(49 citation statements)

References 13 publications

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“…A larger percentage of bidirectional and a lower percentage of receiving connections was observed in epileptogenic tissue (both RA/SOZ), as compared to non‐epileptogenic tissue. Hebbink et al (2017) suggested a node that is driving the seizures is characterized by many connections originating from such a region, and only a few connections toward this region. Removal of this area may have a positive effect on seizure rate.…”

Section: Discussionmentioning

confidence: 99%

“…In the context of epilepsy surgery, the focus on defining only a local SOZ is disputed, as the whole brain network operates together, as is clear from the expression of seizures (Spencer, 2002). It has been suggested that seizure freedom may be best achieved by removing a critical part of tissue that interrupts the epileptic network (Hebbink, Meijer, Huiskamp, van Gils, & Leijten, 2017). …”

Section: Introductionmentioning

confidence: 99%

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Evoked directional network characteristics of epileptogenic tissue derived from single pulse electrical stimulation

Blooijs

Leijten

Rijen

et al. 2018

Human Brain Mapping

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We investigated effective networks constructed from single pulse electrical stimulation (SPES) in epilepsy patients who underwent intracranial electrocorticography. Using graph analysis, we compared network characteristics of tissue within and outside the epileptogenic area. In 21 patients with subdural electrode grids (1 cm interelectrode distance), we constructed a binary, directional network derived from SPES early responses (<100 ms). We calculated in‐degree, out‐degree, betweenness centrality, the percentage of bidirectional, receiving and activating connections, and the percentage of connections toward the (non‐)epileptogenic tissue for each node in the network. We analyzed whether these network measures were significantly different in seizure onset zone (SOZ)‐electrodes compared to non‐SOZ electrodes, in resected area (RA)‐electrodes compared to non‐RA electrodes, and in seizure free compared to not seizure‐free patients. Electrodes in the SOZ/RA showed significantly higher values for in‐degree and out‐degree, both at group level, and at patient level, and more so in seizure‐free patients. These differences were not observed for betweenness centrality. There were also more bidirectional and fewer receiving connections in the SOZ/RA in seizure‐free patients. It appears that the SOZ/RA is densely connected with itself, with only little input arriving from non‐SOZ/non‐RA electrodes. These results suggest that meso‐scale effective network measures are different in epileptogenic compared to normal brain tissue. Local connections within the SOZ/RA are increased and the SOZ/RA is relatively isolated from the surrounding cortex. This offers the prospect of enhanced prediction of epilepsy‐prone brain areas using SPES.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evoked directional network characteristics of epileptogenic tissue derived from single pulse electrical stimulation

Blooijs

Leijten

Rijen

et al. 2018

Human Brain Mapping

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show abstract

“… 2012 ; Hebbink et al. 2017 ). In these models, the activity of the neuronal population underlying each node is modeled by a neural mass.…”

Section: Discussionmentioning

confidence: 99%

A Comparison of Evoked and Non-evoked Functional Networks

et al. 2018

Self Cite

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The growing interest in brain networks to study the brain’s function in cognition and diseases has produced an increase in methods to extract these networks. Typically, each method yields a different network. Therefore, one may ask what the resulting networks represent. To address this issue we consider electrocorticography (ECoG) data where we compare three methods. We derive networks from on-going ECoG data using two traditional methods: cross-correlation (CC) and Granger causality (GC). Next, connectivity is probed actively using single pulse electrical stimulation (SPES). We compare the overlap in connectivity between these three methods as well as their ability to reveal well-known anatomical connections in the language circuit. We find that strong connections in the CC network form more or less a subset of the SPES network. GC and SPES are related more weakly, although GC connections coincide more frequently with SPES connections compared to non-existing SPES connections. Connectivity between the two major hubs in the language circuit, Broca’s and Wernicke’s area, is only found in SPES networks. Our results are of interest for the use of patient-specific networks obtained from ECoG. In epilepsy research, such networks form the basis for methods that predict the effect of epilepsy surgery. For this application SPES networks are interesting as they disclose more physiological connections compared to CC and GC networks. Electronic supplementary material The online version of this article (10.1007/s10548-018-0692-1) contains supplementary material, which is available to authorized users.

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“…in [20]). The removal of nodes in these models and the changes in connectivity could potentially be factors explaining the appearance of new network configurations and the onset of seizures in other nodes [20,21]. New large scale modelling like the Virtual Brain [22]or other approaches [23]appear to be promising perspectives in this field to predict these kind of network changes after surgery.…”

Section: Discussionmentioning

confidence: 99%

The role of stereoelectroencephalography (SEEG) in reevaluation of epilepsy surgery failures

Vaugier

Lagarde

McGonigal

et al. 2018

Epilepsy & Behavior

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Management of patients after initial epilepsy surgical failure is challenging. In this study, we report our experience in using the stereoelectroencephalography (SEEG) method in the reevaluation of patients after initial epilepsy surgical failure. We selected 28 patients examined through SEEG in our department for drug-resistant focal epilepsy following initial epilepsy surgical failure. For each patient, the residual seizure onset zone (rSOZ) as defined by SEEG was classified as either contiguous if the seizure onset zone (SOZ) was focal and close to the surgical cavity (same lobe) or noncontiguous in cases where the SOZ included site(s) distant from the surgical cavity. The rSOZ was defined according to visual analysis of SEEG traces completed by an estimation of the epileptogenicity index (EI). A second surgical procedure was performed in 12 patients (45%). A favorable outcome (Engel class I or II) was obtained in 9/12 patients (6 in Engel class I, 50%). The proportion of patients that had reoperation was higher in the contiguous group (80%) than in the noncontiguous group (22%) (p=0.02). A rSOZ localized in close relation to the initial surgical resection zone (contiguous group) was found in 10 patients (35%). Among them, 8 have since undergone reoperation, and a good outcome (Engel class I) was achieved in 5/8 (63%). A rSOZ involving a distant region from the first surgery was observed in 18 patients (65%) (noncontiguous group). Among them, only 4 have undergone reoperation, leading to a failure in 2 (Engel class III or IV) and a good outcome in 2 (IA). Ten patients had a first standard temporal lobectomy, and in 50% of these cases, the insula was involved in the rSOZ. Stereoelectroencephalography offers a unique way to evaluate the rSOZ at the individual level and thus guide further surgical decision-making. The best results are observed in patients having a focal rSOZ close to the site of the surgical resection in the first surgery.

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Phenomenological network models: Lessons for epilepsy surgery

Cited by 41 publications

References 13 publications

Evoked directional network characteristics of epileptogenic tissue derived from single pulse electrical stimulation

Evoked directional network characteristics of epileptogenic tissue derived from single pulse electrical stimulation

A Comparison of Evoked and Non-evoked Functional Networks

The role of stereoelectroencephalography (SEEG) in reevaluation of epilepsy surgery failures

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