scholarly journals Subsecond EEG-fMRI analysis for presurgical evaluation in focal epilepsy

2020 ◽  
pp. 1-10 ◽  
Author(s):  
Yuji Ito ◽  
Satoshi Maesawa ◽  
Epifanio Bagarinao ◽  
Yu Okai ◽  
Daisuke Nakatsubo ◽  
...  
Keyword(s):  
Surgical Outcomes ◽  
Predictive Value ◽  
Focal Epilepsy ◽  
Epileptic Focus ◽  
Presurgical Evaluation ◽  
Hemodynamic Responses ◽  
Epileptiform Discharges ◽  
Voxel Value ◽  
Fmri Analysis ◽  
Resection Area

OBJECTIVEThe authors recently reported a novel subsecond analysis method of analyzing EEG–functional MRI (fMRI) to improve the detection rate of epileptic focus. This study aims to validate the utility of this method for presurgical evaluation in pharmacoresistant focal epilepsy.METHODSAmong 13 patients with focal epilepsy undergoing presurgical examinations including simultaneous EEG-fMRI at 3T, 11 patients had interictal epileptiform discharges (IEDs) during fMRI. The authors used the sequence of topographic maps during the IEDs as a reference to obtain subsecond fMRI activation maps with the same temporal resolution as the EEG data, and constructed “spike-and-slow-wave-activation-summary” (SSWAS) maps that showed the activation frequency of voxels during IEDs. Clusters were defined by thresholding the SSWAS maps (voxel value > 10), and those containing voxels with the top 3 highest activation frequencies were considered significant. Significant hemodynamic responses using conventional event-related (ER) analysis and SSWAS maps were compared with the resection areas and surgical outcomes at 1 year after surgery.RESULTSUsing ER analysis, 4 (36%) of 11 patients had significant hemodynamic responses. One of 4 patients had significant hemodynamic responses in the resection area and good surgical outcome. Using SSWAS maps, 10 (91%) of 11 patients had significant hemodynamic responses. Six of 10 patients had significant hemodynamic responses in the resection area, and 5 of the 6 patients achieved good surgical outcomes. The remaining 4 patients had significant hemodynamic responses distant from the resection area, and only 1 of the 4 patients achieved good surgical outcomes. The sensitivity, specificity, positive predictive value, and negative predictive value of SSWAS maps were 83.3%, 75.0%, 83.3%, and 75.0%, respectively.CONCLUSIONSThis study demonstrated the clinical utility of SSWAS maps for presurgical evaluation of pharmacoresistant focal epilepsy. The findings indicated that subsecond EEG-fMRI analysis may help surgeons choose the resection areas that could lead to good surgical outcomes.

scholarly journals Synaptic Reshaping and Neuronal Outcomes in the Temporal Lobe Epilepsy

2021 ◽  
Vol 22 (8) ◽  
pp. 3860
Author(s):  
Elisa Ren ◽  
Giulia Curia
Keyword(s):  
Animal Models ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Current Knowledge ◽  
Focal Epilepsy ◽  
Ex Vivo ◽  
Hippocampal Sclerosis ◽  
Control Group ◽  
Epileptogenic Zone ◽  
Epileptiform Discharges

Temporal lobe epilepsy (TLE) is one of the most common types of focal epilepsy, characterized by recurrent spontaneous seizures originating in the temporal lobe(s), with mesial TLE (mTLE) as the worst form of TLE, often associated with hippocampal sclerosis. Abnormal epileptiform discharges are the result, among others, of altered cell-to-cell communication in both chemical and electrical transmissions. Current knowledge about the neurobiology of TLE in human patients emerges from pathological studies of biopsy specimens isolated from the epileptogenic zone or, in a few more recent investigations, from living subjects using positron emission tomography (PET). To overcome limitations related to the use of human tissue, animal models are of great help as they allow the selection of homogeneous samples still presenting a more various scenario of the epileptic syndrome, the presence of a comparable control group, and the availability of a greater amount of tissue for in vitro/ex vivo investigations. This review provides an overview of the structural and functional alterations of synaptic connections in the brain of TLE/mTLE patients and animal models.

scholarly journals Predictive value of exercise renography for presurgical evaluation of nephrogenic hypertension.

Hypertension ◽  
1987 ◽  
Vol 10 (3) ◽  
pp. 280-286 ◽  
Author(s):  
J H Clorius ◽  
J Allenberg ◽  
T Hupp ◽  
L G Strauss ◽  
P Schmidlin ◽  
...  
Keyword(s):  
Predictive Value ◽  
Presurgical Evaluation

Arterial Spin Labeling is a Useful MRI Method for Presurgical Evaluation in MRI-Negative Focal Epilepsy

2021 ◽  
Author(s):  
Martin Kojan ◽  
Martin Gajdoš ◽  
Pavel Říha ◽  
Irena Doležalová ◽  
Zdeněk Řehák ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Focal Epilepsy ◽  
Spin Labeling ◽  
Presurgical Evaluation

Direct Causal Networks for the Study of Transcranial Magnetic Stimulation Effects on Focal Epileptiform Discharges

2015 ◽  
Vol 25 (05) ◽  
pp. 1550006 ◽  
Author(s):  
Dimitris Kugiumtzis ◽  
Vasilios K. Kimiskidis
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Network Structure ◽  
Magnetic Stimulation ◽  
Brain Connectivity ◽  
Effective Connectivity ◽  
Epileptic Focus ◽  
Sham Stimulation ◽  
Focal Seizures ◽  
Epileptiform Discharges ◽  
The Brain

Background: Transcranial magnetic stimulation (TMS) can have inhibitory effects on epileptiform discharges (EDs) of patients with focal seizures. However, the brain connectivity before, during and after EDs, with or without the administration of TMS, has not been extensively explored. Objective: To investigate the brain network of effective connectivity during ED with and without TMS in patients with focal seizures. Methods: For the effective connectivity a direct causality measure is applied termed partial mutual information from mixed embedding (PMIME). TMS-EEG data from two patients with focal seizures were analyzed. Each EEG record contained a number of EDs in the majority of which TMS was administered over the epileptic focus. As a control condition, sham stimulation over the epileptogenic zone or real TMS at a distance from the epileptic focus was also performed. The change in brain connectivity structure was investigated from the causal networks formed at each sliding window. Conclusion: The PMIME could detect distinct changes in the network structure before, within, and after ED. The administration of real TMS over the epileptic focus, in contrast to sham stimulation, terminated the ED prematurely in a node-specific manner and regained the network structure as if it would have terminated spontaneously.

scholarly journals Stereoelectroencephalography-Guided Radiofrequency Thermocoagulation (SEEG-Guided RF-TC) in Patients with Drug-Resistant Focal Epilepsy

2017 ◽  
Vol 3 (1) ◽  
pp. 40-47
Author(s):  
Chengwei Xu ◽  
Wenjing Zhou
Keyword(s):  
Radio Frequency ◽  
Surgical Resection ◽  
Seizure Frequency ◽  
Palliative Treatment ◽  
Focal Epilepsy ◽  
Epileptogenic Zone ◽  
Drug Resistant ◽  
Functional Area ◽  
Presurgical Evaluation ◽  
Epileptic Patients

For some patients with drug-resistant focal epilepsy, we usually select conventional surgical resection, which has brought better outcomes. However, others are not eligible for a conventional open surgical resection of the epileptogenic zone because of the proximity of a functional area or the implication of a larger epileptogenic network. Initially, stereoelectroencephalography (SEEG) exploration was a method of electroencephalography recording that was used in the presurgical evaluation of epileptic patients with complex epilepsy. Later, intracerebral electrodes used for SEEG were applied to produce radio frequency thermocoagulation (RF-TC) in epileptic patients. SEEG-guided RF-TC has produced some promising results, especially in the last dacade. Now, it has become popular as a palliative treatment to reduce seizure frequency in patients with drug-resistant focal epilepsy. This article presents a review of SEEG-guided RF-TC.

scholarly journals The predictive value of hypometabolism in focal epilepsy: a prospective study in surgical candidates

2019 ◽  
Vol 46 (9) ◽  
pp. 1806-1816 ◽  
Author(s):  
José Tomás ◽  
Francesca Pittau ◽  
Alexander Hammers ◽  
Sandrine Bouvard ◽  
Fabienne Picard ◽  
...  
Keyword(s):  
Prospective Study ◽  
Predictive Value ◽  
Focal Epilepsy ◽  
A Prospective Study

scholarly journals Interictal epileptiform discharges shape large-scale intercortical communication

Brain ◽  
2019 ◽  
Vol 142 (11) ◽  
pp. 3502-3513 ◽  
Author(s):  
Prawesh Dahal ◽  
Naureen Ghani ◽  
Adeen Flinker ◽  
Patricia Dugan ◽  
Daniel Friedman ◽  
...  
Keyword(s):  
Large Scale ◽  
Focal Epilepsy ◽  
Brain Dysfunction ◽  
Normal Brain ◽  
Brain Rhythms ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges

Focal epilepsy is associated with large-scale brain dysfunction. Dahal et al. reveal that interictal epileptiform discharges modulate normal brain rhythms in regions beyond the epileptic network, potentially impairing processes that rely heavily upon intercortical communication, such as cognition and memory.

scholarly journals Large-Scale Desynchronization During Interictal Epileptic Discharges Recorded With Intracranial EEG

2020 ◽  
Vol 11 ◽  
Author(s):  
Elie Bou Assi ◽  
Younes Zerouali ◽  
Manon Robert ◽  
Frederic Lesage ◽  
Philippe Pouliot ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Time Course ◽  
Deep Understanding ◽  
Epileptic Focus ◽  
Epileptogenic Focus ◽  
Intracranial Eeg ◽  
Epileptiform Discharges ◽  
Potential Biomarker ◽  
Epileptic Discharges

It is increasingly recognized that deep understanding of epileptic seizures requires both localizing and characterizing the functional network of the region where they are initiated, i. e., the epileptic focus. Previous investigations of the epileptogenic focus' functional connectivity have yielded contrasting results, reporting both pathological increases and decreases during resting periods and seizures. In this study, we shifted paradigm to investigate the time course of connectivity in relation to interictal epileptiform discharges. We recruited 35 epileptic patients undergoing intracranial EEG (iEEG) investigation as part of their presurgical evaluation. For each patient, 50 interictal epileptic discharges (IEDs) were marked and iEEG signals were epoched around those markers. Signals were narrow-band filtered and time resolved phase-locking values were computed to track the dynamics of functional connectivity during IEDs. Results show that IEDs are associated with a transient decrease in global functional connectivity, time-locked to the peak of the discharge and specific to the high range of the gamma frequency band. Disruption of the long-range connectivity between the epileptic focus and other brain areas might be an important process for the generation of epileptic activity. Transient desynchronization could be a potential biomarker of the epileptogenic focus since 1) the functional connectivity involving the focus decreases significantly more than the connectivity outside the focus and 2) patients with good surgical outcome appear to have a significantly more disconnected focus than patients with bad outcomes.

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