The impact of mapping interictal discharges using EEG-fMRI on the epilepsy presurgical clinical decision making process: A prospective study

Markoula, Sofia; Chaudhary, Umair J.; Perani, Suejen; Ciantis, Alessio De; Yadee, Tinonkorn; Duncan, John S.; Diehl, Beate; McEvoy, Andrew W.; Lemieux, Louis

doi:10.1016/j.seizure.2018.07.016

Cited by 16 publications

(17 citation statements)

References 60 publications

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“…It is believed that the region with the maximal BOLD response represents the spike onset zone (the area generating the interictal discharges), which may in turn be a marker of the seizure onset zone (An et al, 2013;Vaudano et al, 2013;Tousseyn et al, 2014;Khoo et al, 2018Khoo et al, , 2017). Thus, EEG-fMRI may yield complementary information within the presurgical workup of surgical remediable epilepsies and potentially impact on the clinical decision-making and patient management process (Zijlmans, 2007;Markoula et al, 2018). In more recent years, task-based fMRI and EEG-fMRI paradigms have increasingly been complemented with task-free or resting-state acquisitions.…”

Section: Functional Mri (Fmri)mentioning

confidence: 99%

MRI essentials in epileptology: a review from the ILAE Imaging Taskforce

Wang¹,

Bernasconi²,

Bernhardt³

et al. 2020

Epileptic Disorders

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Magnetic resonance imaging (MRI) plays a central role in the management and evaluation of patients with epilepsy. It is important that structural MRI scans are optimally acquired and carefully reviewed by trained experts within the context of all available clinical data. The aim of this review is to discuss the essentials of MRI that will be useful to health care providers specialized in epilepsy, as outlined by the competencies and learning objectives of the recently developed ILAE curriculum. This review contains information on basic MRI principles, sequences, field strengths and safety, when to perform and repeat an MRI, epilepsy MRI protocol (HARNESS‐MRI) and the basic reading guidelines, and common epileptic pathologies. More advanced topics such as MRI‐negative epilepsy, functional MRI and diffusion‐weighted imaging are also briefly discussed. Although the available resources can differ markedly across different centers, it is the hope that this review can provide general guidance in the everyday practice of using MRI for patients with epilepsy.

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Section: Functional Mri (Fmri)mentioning

confidence: 99%

MRI essentials in epileptology: a review from the ILAE Imaging Taskforce

Wang¹,

Bernasconi²,

Bernhardt³

et al. 2020

Epileptic Disorders

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“…For each IED class, the presence of significant BOLD clusters was assessed over whole brain using SPM[F]-maps at a statistical threshold of p < 0.001 (uncorrected for family-wise error) and a cluster threshold of five contiguous voxels, as in previous studies from our group and others ( 15 , 22 , 26 , 32 , 40 , 43 ). The resulting SPMs were co-registered with pre- and post-surgical T1-weighted MRI scans using rigid-body registration in SPM.…”

Section: Methodsmentioning

confidence: 99%

“…The concordance of BOLD maps with surgical resection volume (i.e., confirmed EZ) was assessed for each IED class on icEEG using a concordance classification scheme in line with our previous work ( 15 , 22 , 26 , 40 , 43 ) as either:…”

Section: Methodsmentioning

confidence: 99%

“…Simultaneous scalp EEG and functional magnetic resonance imaging (EEG-fMRI) can map interictal epileptiform discharges (IED) and seizure-related blood-oxygen-level-dependent (BOLD) changes (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). In patients with focal cortical dysplasia, IED-related BOLD changes distributed over multiple lobes are associated with poor postsurgical outcome (22).…”

Section: Introductionmentioning

confidence: 99%

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Mapping Epileptic Networks Using Simultaneous Intracranial EEG-fMRI

et al. 2021

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Background: Potentially curative epilepsy surgery can be offered if a single, discrete epileptogenic zone (EZ) can be identified. For individuals in whom there is no clear concordance between clinical localization, scalp EEG, and imaging data, intracranial EEG (icEEG) may be needed to confirm a predefined hypothesis regarding irritative zone (IZ), seizure onset zone (SOZ), and EZ prior to surgery. However, icEEG has limited spatial sampling and may fail to reveal the full extent of epileptogenic network if predefined hypothesis is not correct. Simultaneous icEEG-fMRI has been safely acquired in humans and allows exploration of neuronal activity at the whole-brain level related to interictal epileptiform discharges (IED) captured intracranially.Methods: We report icEEG-fMRI in eight patients with refractory focal epilepsy who had resective surgery and good postsurgical outcome. Surgical resection volume in seizure-free patients post-surgically reflects confirmed identification of the EZ. IEDs on icEEG were classified according to their topographic distribution and localization (Focal, Regional, Widespread, and Non-contiguous). We also divided IEDs by their location within the surgical resection volume [primary IZ (IZ1) IED] or outside [secondary IZ (IZ2) IED]. The distribution of fMRI blood oxygen level-dependent (BOLD) changes associated with individual IED classes were assessed over the whole brain using a general linear model. The concordance of resulting BOLD map was evaluated by comparing localization of BOLD clusters with surgical resection volume. Additionally, we compared the concordance of BOLD maps and presence of BOLD clusters in remote brain areas: precuneus, cuneus, cingulate, medial frontal, and thalamus for different IED classes.Results: A total of 38 different topographic IED classes were identified across the 8 patients: Focal (22) and non-focal (16, Regional = 9, Widespread = 2, Non-contiguous = 5). Twenty-nine IEDs originated from IZ1 and 9 from IZ2. All IED classes were associated with BOLD changes. BOLD maps were concordant with the surgical resection volume for 27/38 (71%) IED classes, showing statistical global maximum BOLD cluster or another cluster in the surgical resection volume. The concordance of BOLD maps with surgical resection volume was greater (p < 0.05) for non-focal (87.5%, 14/16) as compared to Focal (59%, 13/22) IED classes. Additionally, BOLD clusters in remote cortical and deep brain areas were present in 84% (32/38) of BOLD maps, more commonly (15/16; 93%) for non-focal IED-related BOLD maps.Conclusions: Simultaneous icEEG-fMRI can reveal BOLD changes at the whole-brain level for a wide range of IEDs on icEEG. BOLD clusters within surgical resection volume and remote brain areas were more commonly seen for non-focal IED classes, suggesting that a wider hemodynamic network is at play.

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“…To evaluate the concordance between the map of BOLD changes related to IED and the presumed EZ, we applied previously published criteria (16,26). Specifically, "Concordant" (C) refers to maps in which all the clusters (either activation or deactivation) are colocalized with the presumed EZ: within 2 cm of and in the same lobe as EZ; "Concordant Plus" (C+) is applied to fMRI maps with some clusters of significant IEDrelated BOLD changes colocalized with the pEZ and other significant BOLD clusters were located outside the pEZ (within or outside the temporal lobe).…”

Section: Evaluation Of Concordancementioning

confidence: 99%

Temporal Lobe Spikes Affect Distant Intrinsic Connectivity Networks

et al. 2021

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Objective: To evaluate local and distant blood oxygen level dependent (BOLD) signal changes related to interictal epileptiform discharges (IED) in drug-resistant temporal lobe epilepsy (TLE).Methods: Thirty-three TLE patients undergoing EEG–functional Magnetic Resonance Imaging (fMRI) as part of the presurgical workup were consecutively enrolled. First, a single-subject spike-related analysis was performed: (a) to verify the BOLD concordance with the presumed Epileptogenic Zone (EZ); and (b) to investigate the Intrinsic Connectivity Networks (ICN) involvement. Then, a group analysis was performed to search for common BOLD changes in TLE.Results: Interictal epileptiform discharges were recorded in 25 patients and in 19 (58%), a BOLD response was obtained at the single-subject level. In 42% of the cases, BOLD changes were observed in the temporal lobe, although only one patient had a pure concordant finding, with a single fMRI cluster overlapping (and limited to) the EZ identified by anatomo-electro-clinical correlations. In the remaining 58% of the cases, BOLD responses were localized outside the temporal lobe and the presumed EZ. In every patient, with a spike-related fMRI map, at least one ICN appeared to be involved. Four main ICNs were preferentially involved, namely, motor, visual, auditory/motor speech, and the default mode network. At the single-subject level, EEG–fMRI proved to have high specificity (above 65%) in detecting engagement of an ICN and the corresponding ictal/postictal symptom, and good positive predictive value (above 67%) in all networks except the visual one. Finally, in the group analysis of BOLD changes related to IED revealed common activations at the right precentral gyrus, supplementary motor area, and middle cingulate gyrus.Significance: Interictal temporal spikes affect several distant extra-temporal areas, and specifically the motor/premotor cortex. EEG–fMRI in patients with TLE eligible for surgery is recommended not for strictly localizing purposes rather it might be useful to investigate ICNs alterations at the single-subject level.

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The impact of mapping interictal discharges using EEG-fMRI on the epilepsy presurgical clinical decision making process: A prospective study

Abstract: The study is a prospective observational cohort study specifically designed to assess the impact of EEG-fMRI on the clinical decision making process, suggesting a significant influence of EEG-fMRI on epilepsy surgery planning.

Cited by 16 publications

References 60 publications

MRI essentials in epileptology: a review from the ILAE Imaging Taskforce

MRI essentials in epileptology: a review from the ILAE Imaging Taskforce

Mapping Epileptic Networks Using Simultaneous Intracranial EEG-fMRI

Temporal Lobe Spikes Affect Distant Intrinsic Connectivity Networks

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