scholarly journals Validating EEG, MEG and combined MEG and EEG beamforming for an estimation of the epileptogenic zone in focal cortical dysplasia

2021 ◽  
Author(s):  
Frank Neugebauer ◽  
Marios Antonakakis ◽  
Kanjana Unnwongse ◽  
Yaroslav Parpaley ◽  
Jörg Wellmer ◽  
...  
Keyword(s):  
Regularization Parameter ◽  
Focal Cortical Dysplasia ◽  
Estimation Method ◽  
Cortical Dysplasia ◽  
Source Analysis ◽  
Seizure Freedom ◽  
Epileptogenic Zone ◽  
Scanning Method ◽  
Eeg Source Analysis ◽  
Skull Conductivity

AbstractMEG and EEG source analysis is frequently used for the presurgical evaluation of pharma-coresistant epilepsy patients. The source localization of the epileptogenic zone depends, among other aspects, on the selected inverse and forward approaches and their respective parameter choices. In this validation study, we compare for the inverse problem the standard dipole scanning method with two beamformer approaches and we investigate the influence of the covariance estimation method and the strength of regularization on the localization performance for EEG, MEG and combined EEG and MEG. For forward modeling, we investigate the difference between calibrated six-compartment and standard three-compartment head modeling. In a retrospective study of two patients with focal epilepsy due to focal cortical dysplasia type IIb and seizure-freedom following lesionectomy or radiofrequency-guided thermocoagulation, we used the distance of the localization of interictal epileptic spikes to the resection cavity resp. rediofrequency lesion as reference for good localization. We found that beamformer localization can be sensitive to the choice of the regularization parameter, which has to be individually optimized. Estimation of the covariance matrix with averaged spike data yielded more robust results across the modalities. MEG was the dominant modality and provided a good localization in one case, while it was EEG for the other. When combining the modalities, the good results of the dominant modality were mostly not spoiled by the weaker modality. For appropriate regularization parameter choices, the beamformer localized better than the standard dipole scan. Compared to the importance of an appropriate regularization, the sensitivity of the localization to the head modeling was smaller, due to similar skull conductivity modeling and the fixed source space without orientation constraint.

scholarly journals Validating EEG, MEG and Combined MEG and EEG Beamforming for an Estimation of the Epileptogenic Zone in Focal Cortical Dysplasia

2022 ◽  
Vol 12 (1) ◽  
pp. 114
Author(s):  
Frank Neugebauer ◽  
Marios Antonakakis ◽  
Kanjana Unnwongse ◽  
Yaroslav Parpaley ◽  
Jörg Wellmer ◽  
...  
Keyword(s):  
Regularization Parameter ◽  
Focal Cortical Dysplasia ◽  
Estimation Method ◽  
Cortical Dysplasia ◽  
Source Analysis ◽  
Seizure Freedom ◽  
Epileptogenic Zone ◽  
Scanning Method ◽  
Eeg Source Analysis ◽  
Skull Conductivity

MEG and EEG source analysis is frequently used for the presurgical evaluation of pharmacoresistant epilepsy patients. The source localization of the epileptogenic zone depends, among other aspects, on the selected inverse and forward approaches and their respective parameter choices. In this validation study, we compare the standard dipole scanning method with two beamformer approaches for the inverse problem, and we investigate the influence of the covariance estimation method and the strength of regularization on the localization performance for EEG, MEG, and combined EEG and MEG. For forward modelling, we investigate the difference between calibrated six-compartment and standard three-compartment head modelling. In a retrospective study, two patients with focal epilepsy due to focal cortical dysplasia type IIb and seizure freedom following lesionectomy or radiofrequency-guided thermocoagulation (RFTC) used the distance of the localization of interictal epileptic spikes to the resection cavity resp. RFTC lesion as reference for good localization. We found that beamformer localization can be sensitive to the choice of the regularization parameter, which has to be individually optimized. Estimation of the covariance matrix with averaged spike data yielded more robust results across the modalities. MEG was the dominant modality and provided a good localization in one case, while it was EEG for the other. When combining the modalities, the good results of the dominant modality were mostly not spoiled by the weaker modality. For appropriate regularization parameter choices, the beamformer localized better than the standard dipole scan. Compared to the importance of an appropriate regularization, the sensitivity of the localization to the head modelling was smaller, due to similar skull conductivity modelling and the fixed source space without orientation constraint.

Surgery for Nontumoral Insular Epilepsy Explored by Stereoelectroencephalography

Neurosurgery ◽  
2016 ◽  
Vol 79 (4) ◽  
pp. 578-588 ◽  
Author(s):  
Guillaume Gras-Combe ◽  
Lorella Minotti ◽  
Dominique Hoffmann ◽  
Alexandre Krainik ◽  
Philippe Kahane ◽  
...  
Keyword(s):  
Focal Cortical Dysplasia ◽  
Intractable Epilepsy ◽  
Insular Cortex ◽  
Cavernous Angioma ◽  
Cortical Dysplasia ◽  
Electrode Placement ◽  
Seizure Freedom ◽  
Epileptogenic Zone ◽  
Pharmacoresistant Epilepsy ◽  
The Right

Abstract BACKGROUND Hidden by the perisylvian operculi, insular cortex has long been underexplored in the context of epilepsy surgery. Recent studies advocated stereoelectroencephalography (SEEG) as a reliable tool to explore insular cortex and its involvement in intractable epilepsy and suggested that insular seizures could be an underestimated entity. However, the results of insular resection to treat pharmacoresistant epilepsy are rarely reported. OBJECTIVE We report 6 consecutive cases of right insular resection performed based on anatomoelectroclinical correlations provided by SEEG. METHODS Six right-handed patients (3 male, 3 female) with drug-resistant epilepsy underwent comprehensive presurgical evaluation. Based on video electroencephalographic recordings, they all underwent SEEG evaluation with bilateral (n = 4) or unilateral right (n = 2) insular depth electrode placement. All patients had both orthogonal and oblique (1 anterior, 1 posterior) insular electrodes (n = 4-6 electrodes). Preoperative magnetic resonance imaging findings were normal in 4 patients, 1 patient had right insular focal cortical dysplasia, and 1 patient had a right opercular postoperative scar (cavernous angioma). All patients underwent right partial insular corticectomy via the subpial transopercular approach. RESULTS Intracerebral recordings demonstrated an epileptogenic zone confined to the right insula in all patients. After selective insular resection, 5 of 6 patients were seizure free (Engel class I) with a mean follow-up of 36.2 months (range, 18-68 months). Histological findings revealed focal cortical dysplasia in 5 patients and a gliosis scar in 1 patient. All patients had minor transient neurological deficit (eg, facial paresis, dysarthria). CONCLUSION Insular resection based on SEEG findings can be performed safely with a significant chance of seizure freedom.

Clinical Application of 7T Magnetic Resonance Imaging in Patients with Focal Cortical Dysplasia IIa and Epilepsy

2020 ◽  
pp. 1-9
Author(s):  
Tinghong Liu ◽  
Huilou Liang ◽  
Jianfei Cui ◽  
Kaibao Sun ◽  
Shaohui Zhang ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Focal Cortical Dysplasia ◽  
Cortical Dysplasia ◽  
Preoperative Imaging ◽  
Seizure Freedom ◽  
Resonance Imaging ◽  
3T Mri ◽  
Strength Grade

<b><i>Background:</i></b> Focal cortical dysplasia (FCD) is one of the most important pathogenic findings in patients with extratemporal lobe epilepsy. Magnetic resonance imaging (MRI)-negative is the most important negative factor to predict postoperative seizure freedom; however, FCD-I and part of FCD-IIa are MRI-negative on routine MRI. <b><i>Objectives:</i></b> To explore the diagnostic values of 7T MRI and its new scan sequences in epilepsy patients with FCD-IIa. <b><i>Methods:</i></b> To include patients with focal seizure and suspicious focal abnormal imaging on 3T MRI during preoperative evaluation and perform a 7T MRI scan with white matter-suppressed (WMS) and gray-white matter tissue border enhancement (GWBE) sequences, resective epilepsy surgery, and postoperative pathological finding of FCD-IIa. The preoperative qualitative and localization significance of 7T MRI and 3T MRI in lesions with FCD-IIa was compared, and then, the imaging characteristics of lesions with FCD-IIa on 7T MRI were analyzed. <b><i>Results:</i></b> Ten cases were enrolled in this study. Seven tesla MRI presented high spatial resolutions and a high signal-to-noise ratio. WMS and GWBE could selectively suppress the signal of special tissue and improved the possibility of FCD findings. FCD-IIa showed abnormal thickness of gray matter and a blurring border and was hypointense on 7T MRI compared with 3T MRI. Seven patients showed improvement in the qualitative diagnosis strength grade of FCD, and 6 subjects showed improvement in the localization strength grade of the lesion border after careful reading of the 7T MR images. Significant differences were found in the qualitative diagnosis of FCD (<i>p</i> &#x3c; 0.05) and localization of the lesion border (<i>p</i> &#x3c; 0.05) between the neuroimaging diagnoses based on 3T MRI and the findings based on 7T MRI. <b><i>Conclusion:</i></b> 7T MRI with WMS and GWBE sequences shows application value in the preoperative imaging diagnosis of lesions with FCD-IIa in epilepsy patients.

scholarly journals Contralateral insular epileptogenic hub causing seizure relapse after opercular focal cortical dysplasia surgery and response to radiofrequency thermocoagulation: illustrative case

2021 ◽  
Vol 2 (5) ◽  
Author(s):  
Pushkaran Jayapaul ◽  
Shameer Aslam ◽  
Bindhu Mangalath Rajamma ◽  
Siby Gopinath ◽  
Ashok Pillai
Keyword(s):  
Focal Cortical Dysplasia ◽  
Positron Emission Tomography Imaging ◽  
Cortical Dysplasia ◽  
Illustrative Case ◽  
Epileptogenic Zone ◽  
Pharmacoresistant Epilepsy ◽  
Novel Technique ◽  
Positron Emission ◽  
Seizure Relapse ◽  
The Right

BACKGROUND The reevaluation and management of seizure relapse following resective surgery in magnetic resonance imaging (MRI)-negative pharmacoresistant epilepsy remains a significant challenge. OBSERVATIONS A 25-year-old right-handed male with medically refractory epilepsy presented with nonlocalizing electroencephalography (EEG) and MRI. Stereo-EEG (SEEG) implantation based on semiology and positron emission tomography imaging revealed a left frontal opercular focus with rapid bilateral insular ictal synchrony. The initial epileptogenic zone was resected and pathologically proven to be type 2A focal cortical dysplasia (FCD). Seizure relapse after 9 months was eventually reinvestigated, and repeat SEEG revealed a secondary epileptogenic focus in the contralateral insula. A novel technique of volumetric stereotactic radiofrequency ablation (vRFA) was utilized for the right insular focus, following which, the patient remains seizure-free for 20 months. He suffered a transient bilateral opercular syndrome following the second intervention that eventually resolved. LESSONS The authors present clinical evidence to suggest epileptogenic nodes distant from the primary focus as a mechanism for seizure relapse following FCD surgery and the importance of bilateral insular SEEG coverage. The authors also describe a novel technique of minimally invasive vRFA that allows ablation of a larger volume of cerebral cortex when compared to conventional bedside SEEG electrode thermocoagulation.

scholarly journals On The Use of Machine Learning Algorithms to Classify Focal Cortical Dysplasia on MRI

2021 ◽  
Author(s):  
João Guilherme Pereira ◽  
Matheus de Freitas Oliveira Baffa ◽  
Fabrício Henrique Simozo ◽  
Luiz Otavio Murta Junior ◽  
Joaquim Cezar Felipe
Keyword(s):  
Deep Neural Network ◽  
Surgical Intervention ◽  
Refractory Epilepsy ◽  
Focal Cortical Dysplasia ◽  
Cortical Dysplasia ◽  
Machine Learning Algorithms ◽  
Textural Features ◽  
Epileptogenic Zone ◽  
Neural Network Classifier ◽  
Multiple Classifiers

Refractory epilepsy is a condition characterized by epileptic seizure occurrence which cannot be controlled with antiepileptic drugs. This condition is associated with an excessive neuronal discharge produced by a group of neurons in a certain epileptogenic zone. Focal Cortical Dysplasia (FCD), usually found in these zones, was detected as one of the main causes of refractory epilepsy. In these cases, surgical intervention is necessary to minimize or eliminate the seizure occurrences. However, surgical treatment is only indicated in cases where there is complete certainty of the FCD. In order to assist neurosurgeons to detect precisely these regions, this paper aims to develop a classification method to detect FCD on MRI based on morphological and textural features from a voxel-level perspective. Multiple classifiers were tested throughout the extracted features, the best results achieved an accuracy of 91.76% using a Deep Neural Network classifier and 96.15% with J48 Decision Tree. The set of evaluating metrics showed that the results are promising.

Multilobar Epilepsy Surgery in Childhood and Adolescence: Predictors of Long-Term Seizure Freedom

Neurosurgery ◽  
2020 ◽  
Vol 88 (1) ◽  
pp. 174-182
Author(s):  
Evangelos Kogias ◽  
Thomas Bast ◽  
Susanne Schubert-Bast ◽  
Gert Wiegand ◽  
Armin Brandt ◽  
...  
Keyword(s):  
Epilepsy Surgery ◽  
Seizure Control ◽  
Focal Cortical Dysplasia ◽  
Benign Tumors ◽  
Seizure Freedom ◽  
Childhood And Adolescence ◽  
Epileptogenic Zone ◽  
Seizure Recurrence ◽  
Eloquent Cortex

Abstract BACKGROUND Although multilobar resections correspond to one-fifth of pediatric epilepsy surgery, there are little data on long-term seizure control. OBJECTIVE To investigate the long-term seizure outcomes of children and adolescents undergoing multilobar epilepsy surgery and identify their predictors. METHODS In this retrospective study, we considered 69 consecutive patients that underwent multilobar epilepsy surgery at the age of 10.0 ± 5.0 yr (mean ± SD). The magnetic resonance imaging revealed a lesion in all but 2 cases. Resections were temporo-parieto(-occipital) in 30%, temporo-occipital in 41%, parieto-occipital in 16%, and fronto-(temporo)-parietal in 13% cases. Etiologies were determined as focal cortical dysplasia in 67%, perinatal or postnatal ischemic lesions in 23%, and benign tumors in 10% of cases. RESULTS At last follow-up of median 9 yr (range 2.8-14.8), 48% patients were seizure free; 33% were off antiepileptic drugs. 10% of patients, all with dysplastic etiology, required reoperations: 4 of 7 achieved seizure freedom. Seizure recurrence occurred mostly (80%) within the first 6 mo. Among presurgical variables, only an epileptogenic zone far from eloquent cortex independently correlated with significantly higher rates of seizure arrest in multivariate analysis. Among postsurgical variables, the absence of residual lesion and of acute postsurgical seizures was independently associated with significantly higher rates of seizure freedom. CONCLUSION Our study demonstrates that multilobar epilepsy surgery is effective regarding long-term seizure freedom and antiepileptic drug withdrawal in selected pediatric candidates. Epileptogenic zones–and lesions–localized distant from eloquent cortex and, thus, fully resectable predispose for seizure control. Acute postsurgical seizures are critical markers of seizure recurrence that should lead to prompt reevaluation.

scholarly journals Seizure control after subtotal lesional resection

2013 ◽  
Vol 34 (6) ◽  
pp. E1 ◽  
Author(s):  
William C. Gump ◽  
Karen L. Skjei ◽  
Shefali N. Karkare
Keyword(s):  
Seizure Control ◽  
Focal Cortical Dysplasia ◽  
Extent Of Resection ◽  
Cortical Dysplasia ◽  
Vascular Lesions ◽  
Subtotal Resection ◽  
Seizure Freedom ◽  
Total Resection ◽  
Significant Opportunity ◽  
Significant Superiority

Reports on seizure outcomes following surgery for lesional epilepsy consistently cite extent of resection as a significant predictor of outcome. Unfortunately, gross-total resection is not technically feasible in all cases of medically refractory tumor-associated epilepsy. Here, the authors present the case of a 4-year-old girl whose epilepsy was medically controlled after 1-stage electrocorticography-guided subtotal resection (STR) of a large diffuse protoplasmic astrocytoma. They also review the modern literature on epilepsy associated with brain tumors. Outcomes are compared with those following surgical treatment of focal cortical dysplasia and vascular lesions. Gross-total lesional resection shows significant superiority across pathologies and anatomical regions. Despite a considerable number of STRs yielding seizure freedom, other favorable treatment factors have not been defined. Although gross-total lesional resection, if possible, is clearly superior, tailored surgery may still offer patients a significant opportunity for a good outcome. Treatment factors yielding successful seizure control following STR remain to be fully elucidated.

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