Epilepsy as a dynamical disorder orchestrated by epileptogenic zone: a review

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.

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Efficient automated localization of ECoG electrodes in CT images via shape analysis

International Journal of Computer Assisted Radiology and Surgery ◽

10.1007/s11548-021-02325-0 ◽

2021 ◽

Vol 16 (4) ◽

pp. 543-554

Author(s):

Jessica Centracchio ◽

Antonio Sarno ◽

Daniele Esposito ◽

Emilio Andreozzi ◽

Luigi Pavone ◽

...

Keyword(s):

Shape Analysis ◽

Focal Epilepsy ◽

Support Vector ◽

Epileptogenic Zone ◽

Platinum Electrodes ◽

Public Repository ◽

Automated Method ◽

Depth Electrodes ◽

Ethical Approval ◽

Cortical Regions

Abstract Purpose People with drug-refractory epilepsy are potential candidates for surgery. In many cases, epileptogenic zone localization requires intracranial investigations, e.g., via ElectroCorticoGraphy (ECoG), which uses subdural electrodes to map eloquent areas of large cortical regions. Precise electrodes localization on cortical surface is mandatory to delineate the seizure onset zone. Simple thresholding operations performed on patients’ computed tomography (CT) volumes recognize electrodes but also other metal objects (e.g., wires, stitches), which need to be manually removed. A new automated method based on shape analysis is proposed, which provides substantially improved performances in ECoG electrodes recognition. Methods The proposed method was retrospectively tested on 24 CT volumes of subjects with drug-refractory focal epilepsy, presenting a large number (> 1700) of round platinum electrodes. After CT volume thresholding, six geometric features of voxel clusters (volume, symmetry axes lengths, circularity and cylinder similarity) were used to recognize the actual electrodes among all metal objects via a Gaussian support vector machine (G-SVM). The proposed method was further tested on seven CT volumes from a public repository. Simultaneous recognition of depth and ECoG electrodes was also investigated on three additional CT volumes, containing penetrating depth electrodes. Results The G-SVM provided a 99.74% mean classification accuracy across all 24 single-patient datasets, as well as on the combined dataset. High accuracies were obtained also on the CT volumes from public repository (98.27% across all patients, 99.68% on combined dataset). An overall accuracy of 99.34% was achieved for the recognition of depth and ECoG electrodes. Conclusions The proposed method accomplishes automated ECoG electrodes localization with unprecedented accuracy and can be easily implemented into existing software for preoperative analysis process. The preliminary yet surprisingly good results achieved for the simultaneous depth and ECoG electrodes recognition are encouraging. Ethical approval n°NCT04479410 by “IRCCS Neuromed” (Pozzilli, Italy), 30th July 2020.

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The benefit of the diffusion kurtosis imaging in presurgical evaluation in patients with focal MR-negative epilepsy

Scientific Reports ◽

10.1038/s41598-021-92804-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Michaela Bartoňová ◽

Marek Bartoň ◽

Pavel Říha ◽

Lubomír Vojtíšek ◽

Milan Brázdil ◽

...

Keyword(s):

Refractory Epilepsy ◽

Diffusion Kurtosis Imaging ◽

Epileptogenic Zone ◽

Diffusion Weighted Mri ◽

Specific Detection ◽

Presurgical Evaluation ◽

Brain Areas ◽

Specific Restriction ◽

Diffusion Kurtosis ◽

Selection Of

AbstractThe effectivity of diffusion-weighted MRI methods in detecting the epileptogenic zone (EZ) was tested. Patients with refractory epilepsy (N=25) who subsequently underwent resective surgery were recruited. First, the extent of white matter (WM) asymmetry from mean kurtosis (MK) was calculated in order to detect the lobe with the strongest impairment. Second, a newly developed metric was used, reflecting a selection of brain areas with concurrently increased mean Diffusivity, reduced fractional Anisotropy, and reduced mean Kurtosis (iDrArK). A two-step EZ detection was performed as (1) lobe-specific detection, (2) iDrArK voxel-wise detection (with a possible lobe-specific restriction if the result of the first step was significant in a given subject). The method results were compared with the surgery resection zones. From the whole cohort (N=25), the numbers of patients with significant results were: 10 patients in lobe detection and 9 patients in EZ detection. From these subsets of patients with significant results, the impaired lobe was successfully detected with 100% accuracy; the EZ was successfully detected with 89% accuracy. The detection of the EZ using iDrArK was substantially more successful when compared with solo diffusional parameters (or their pairwise combinations). For a subgroup with significant results from step one (N=10), iDrArK without lobe restriction achieved 37.5% accuracy; lobe-restricted iDrArK achieved 100% accuracy. The study shows the plausibility of MK for detecting widespread WM changes and the benefit of combining different diffusional voxel-wise parameters.

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Continuous Intraoperative Neurophysiological Monitoring of the Motor Pathways Using Depth Electrodes During Surgical Resection of an Epileptogenic Lesion: A Novel Technique

Operative Neurosurgery ◽

10.1093/ons/opaa463 ◽

2021 ◽

Author(s):

Denise F Chen ◽

Jon T Willie ◽

David Cabrera ◽

Katie L Bullinger ◽

Ioannis Karakis

Keyword(s):

Motor Cortex ◽

Surgical Resection ◽

Radiation Necrosis ◽

World Health ◽

Intraoperative Neurophysiological Monitoring ◽

Neurophysiological Monitoring ◽

Epileptogenic Zone ◽

Motor Pathways ◽

Depth Electrodes ◽

Epileptogenic Lesion

Abstract BACKGROUND AND IMPORTANCE Intraoperative neurophysiological monitoring of the motor pathways during epilepsy surgery is essential to safely achieve maximal resection of the epileptogenic zone. Motor evoked potential (MEP) recording is usually performed intermittently during resection using a handheld stimulator or continuously through an electrode array placed on the motor cortex. We present a novel variation of continuous MEP acquisition through previously implanted depth electrodes in the perirolandic cortex. CLINICAL PRESENTATION A 60-yr-old woman with a history of a left frontal meningioma (World Health Organization [WHO] grade II) treated with surgical resection and radiation presented with residual right hemiparesis and refractory epilepsy. Imaging demonstrated a perirolandic lesion with surrounding edema and mass effect in the prior surgical site, suspicious for radiation necrosis versus tumor recurrence. Presurgical electrocorticography (ECoG) with orthogonal, stereotactically implanted depth electrodes (stereoelectroencephalography [SEEG]) of the perirolandic cortex captured seizure onsets from the supplementary motor area (SMA) and primary motor cortex (PMC). The patient underwent a left frontal craniotomy for repeat resection and tissue diagnosis. Intraoperative ECoG and MEPs were obtained continuously with direct cortical stimulation through the indwelling SEEG electrodes in the PMC. Maximal resection was achieved with preservation of direct cortical MEPs and without deterioration of her baseline hemiparesis. Biopsy revealed radiation necrosis. At 30-mo follow-up, the patient had only rare seizures (Engel class IIB). CONCLUSION Intraoperative cortical MEP acquisition through implanted SEEG electrode arrays is a potentially safe and effective alternative approach to continuously monitor the motor pathways during the resection of a perirolandic epileptogenic lesion, without the need for surgical interruptions.

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PP482 Invasive Electroencephalography In The Pre-Surgical Diagnosis Of Pharmacoresistant Epilepsy

International Journal of Technology Assessment in Health Care ◽

10.1017/s0266462320001828 ◽

2020 ◽

Vol 36 (S1) ◽

pp. 38-38

Author(s):

Andrey Avdeyev ◽

Azat Shpekov ◽

Valeriy Benberin ◽

Nasrulla Shanazarov ◽

Leilya Ismailova ◽

...

Keyword(s):

Cost Effectiveness ◽

Meta Analysis ◽

Epileptogenic Zone ◽

Pharmacoresistant Epilepsy ◽

Simple Method ◽

Integrated Method ◽

Accurate Localization ◽

Functional Zones ◽

Severity Of The Disease ◽

Government Reimbursement

IntroductionWorldwide, more than 50 million people suffer from epilepsy, and there are 16–51 new cases per 100,000 population each year. Up to 30 percent of patients with epilepsy are pharmacoresistant, who are candidates for surgical treatment. Invasive electroencephalography (iEEG) is a mandatory method in the arsenal of epileptic centers, and is gradually becoming the gold standard for invasive determination of boundaries between the affected and functional zones of the cortex and subcortical brain. Treatment costs correlate with the severity of the disease, with patients having uncontrolled seizures incurring eight times the costs compared to those with controlled epilepsy.MethodsTo assess the clinical and cost-effectiveness of the iEEG in the pre-surgical diagnosis of pharmacoresistant epilepsy, a systematic search of literature by keywords in the MEDLINE database was conducted. The search resulted in sixty-six articles. The analysis included twenty studies that met the search criteria.ResultsMost studies including meta-analysis show very low rates of complications of iEEG. Literature data demonstrate cost-effectiveness of the method in patients with pharmacoresistant epilepsy in comparison with continued antiepileptic drug therapy. As an integrated method, rather than a simple method, it takes maximum account of clinical, neurophysiological and anatomical-functional data to achieve accurate localization of the epileptogenic zone. Currently, iEEG is a clinically effective method to improve the safety and specificity of resective surgery.ConclusionsWith the use of iEEG, mortality and disability of patients with pharmacoresistant epilepsy will be significantly reduced. It has also been proven that epilepsy surgery leads to significant financial savings in the treatment of pharmacoresistant epilepsy. The results of the clinical and economic evaluation (mini-HTA report) have been submitted to the Ministry of Healthcare for decision-making on including iEEG in government reimbursement system.

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EEG Source Imaging (ESI) utility in clinical practice

Biomedical Engineering / Biomedizinische Technik ◽

10.1515/bmt-2019-0128 ◽

2020 ◽

Vol 65 (6) ◽

pp. 673-682

Author(s):

Pegah Khosropanah ◽

Eric Tatt-Wei Ho ◽

Kheng-Seang Lim ◽

Si-Lei Fong ◽

Minh-An Thuy Le ◽

...

Keyword(s):

Focal Epilepsy ◽

Cost Effective ◽

Head Model ◽

Computational Technique ◽

Epileptogenic Zone ◽

Clinical Tool ◽

Source Imaging ◽

Localization Accuracy ◽

Eeg Source Imaging ◽

Surgical Evaluation

AbstractEpilepsy surgery is an important treatment modality for medically refractory focal epilepsy. The outcome of surgery usually depends on the localization accuracy of the epileptogenic zone (EZ) during pre-surgical evaluation. Good localization can be achieved with various electrophysiological and neuroimaging approaches. However, each approach has its own merits and limitations. Electroencephalography (EEG) Source Imaging (ESI) is an emerging model-based computational technique to localize cortical sources of electrical activity within the brain volume, three-dimensionally. ESI based pre-surgical evaluation gives an overall clinical yield of 73–91%, depending on choice of head model, inverse solution and EEG electrode density. It is a cost effective, non-invasive method which provides valuable additional information in presurgical evaluation due to its high localizing value specifically in MRI-negative cases, extra or basal temporal lobe epilepsy, multifocal lesions such as tuberous sclerosis or cases with multiple hypotheses. Unfortunately, less than 1% of surgical centers in developing countries use this method as a part of pre-surgical evaluation. This review promotes ESI as a useful clinical tool especially for patients with lesion-negative MRI to determine EZ cost-effectively with high accuracy under the optimized conditions.

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Stereoelectroencephalography

Neurosurgery ◽

10.1227/neu.0b013e31827d1161 ◽

2012 ◽

Vol 72 (3) ◽

pp. 353-366 ◽

Cited By ~ 267

Author(s):

Francesco Cardinale ◽

Massimo Cossu ◽

Laura Castana ◽

Giuseppe Casaceli ◽

Marco Paolo Schiariti ◽

...

Keyword(s):

Interquartile Range ◽

Entry Point ◽

Target Point ◽

Epileptogenic Zone ◽

Localization Error ◽

Drug Resistant ◽

Robot Assisted ◽

Data Set ◽

Essential Information

Abstract BACKGROUND: Stereoelectroencephalography (SEEG) methodology, originally developed by Talairach and Bancaud, is progressively gaining popularity for the presurgical invasive evaluation of drug-resistant epilepsies. OBJECTIVE: To describe recent SEEG methodological implementations carried out in our center, to evaluate safety, and to analyze in vivo application accuracy in a consecutive series of 500 procedures with a total of 6496 implanted electrodes. METHODS: Four hundred nineteen procedures were performed with the traditional 2-step surgical workflow, which was modified for the subsequent 81 procedures. The new workflow entailed acquisition of brain 3-dimensional angiography and magnetic resonance imaging in frameless and markerless conditions, advanced multimodal planning, and robot-assisted implantation. Quantitative analysis for in vivo entry point and target point localization error was performed on a sub-data set of 118 procedures (1567 electrodes). RESULTS: The methodology allowed successful implantation in all cases. Major complication rate was 12 of 500 (2.4%), including 1 death for indirect morbidity. Median entry point localization error was 1.43 mm (interquartile range, 0.91-2.21 mm) with the traditional workflow and 0.78 mm (interquartile range, 0.49-1.08 mm) with the new one (P < 2.2 × 10−16). Median target point localization errors were 2.69 mm (interquartile range, 1.89-3.67 mm) and 1.77 mm (interquartile range, 1.25-2.51 mm; P < 2.2 × 10−16), respectively. CONCLUSION: SEEG is a safe and accurate procedure for the invasive assessment of the epileptogenic zone. Traditional Talairach methodology, implemented by multimodal planning and robot-assisted surgery, allows direct electrical recording from superficial and deep-seated brain structures, providing essential information in the most complex cases of drug-resistant epilepsy.

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Does Tc-99m ECD ictal brain SPECT have incremental value in localization of epileptogenic zone and predicting postoperative seizure freedom in cases with discordant video electroencephalogram and MRI findings?

Nuclear Medicine Communications ◽

10.1097/mnm.0000000000001240 ◽

2020 ◽

Vol 41 (9) ◽

pp. 858-870

Author(s):

Shwetal Uday Pawar ◽

Sangeeta Hasmukh Ravat ◽

Dattatraya Prakash Muzumdar ◽

Shilpa Sushilkumar Sankhe ◽

Akash Harakchand Chheda ◽

...

Keyword(s):

Brain Spect ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Mri Findings ◽

Incremental Value ◽

Postoperative Seizure

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Localization of epileptogenic zone in temporal lobe epilepsy by ictal scalp EEG

Seizure ◽

10.1053/seiz.2001.0603 ◽

2002 ◽

Vol 11 (3) ◽

pp. 163-168 ◽

Cited By ~ 14

Author(s):

Yuzo Sakai ◽

Hiromi Nagano ◽

Ayumi Sakata ◽

Sachiko Kinoshita ◽

Naotaka Hamasaki ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Epileptogenic Zone ◽

Scalp Eeg

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Surgical treatment of bilateral temporal lobe pharmacoresistant epilepsy

Vestnik nevrologii, psihiatrii i nejrohirurgii (Bulletin of Neurology, Psychiatry and Neurosurgery) ◽

10.33920/med-01-2008-06 ◽

2020 ◽

pp. 60-82

Author(s):

Igor Sergeevich Trifonov ◽

Mikhail Vladimirovich Sinkin ◽

Elena Vladimirovna Grigoryeva ◽

Rashid Abdurakhmanovich Navruzov

Keyword(s):

Surgical Treatment ◽

Temporal Lobe ◽

Clinical Picture ◽

Clinical Manifestations ◽

Epileptogenic Zone ◽

Pharmacoresistant Epilepsy ◽

Modern Methods ◽

Selection For ◽

Selection Of Patients ◽

Selection Of

Surgical treatment of bilateral temporal lobe pharmacoresistant epilepsy is associated with some difficulties: particularly, the lack of stereotypical clinical picture in the same patient and controversial data on modern methods of diagnostics — all these statements make identifying epileptogenic zone more difficult and lack of clear criteria for the selection of patients for surgical treatment. In this review, issues of aetiology, pathogenesis, clinical manifestations and criteria for the selection for surgical treatment suggested by different authors are presented.

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