An evaluation of kurtosis beamforming in magnetoencephalography to localize the epileptogenic zone in drug resistant epilepsy patients

ABSTRACT Neurocysticercosis is one of the most common risk factors for epilepsy but its association with drug-resistant epilepsy remains uncertain. Conjectures of an association with drug-resistant epilepsy have been fueled by reports of an association between calcific neurocysticercosis lesions (CNL) and hippocampal sclerosis (HS) from specialized epilepsy centers in Taenia solium-endemic regions. The debate arising from these reports is whether the association is causal. Evidence for the association is not high quality but sufficiently persuasive to merit further investigation with longitudinal imaging studies in population-based samples from geographically-diverse regions. The other controversial point is the choice of a surgical approach for drug-resistant epilepsy associated with CNL-HS. Three approaches have been described: standard anteromesial temporal lobectomy, lesionectomy involving a CNL alone and lesionectomy with anteromesial temporal lobectomy (for dual pathology); reports of the latter two approaches are limited. Presurgical evaluation should consider possibilities of delineating the epileptogenic zone/s in accordance with all three approaches.

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Medically resistant pediatric insular-opercular/perisylvian epilepsy. Part 1: invasive monitoring using the parasagittal transinsular apex depth electrode

Journal of Neurosurgery Pediatrics ◽

10.3171/2016.4.peds15636 ◽

2016 ◽

Vol 18 (5) ◽

pp. 511-522 ◽

Cited By ~ 13

Author(s):

Alexander G. Weil ◽

Aria Fallah ◽

Evan C. Lewis ◽

Sanjiv Bhatia

Keyword(s):

Epilepsy Surgery ◽

Electrode Placement ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Depth Electrodes ◽

Depth Electrode ◽

Age At Surgery ◽

Feasible Alternative ◽

The Mean ◽

Drug Resistant Epilepsy

OBJECTIVE Insular lobe epilepsy (ILE) is an under-recognized cause of extratemporal epilepsy and explains some epilepsy surgery failures in children with drug-resistant epilepsy. The diagnosis of ILE usually requires invasive investigation with insular sampling; however, the location of the insula below the opercula and the dense middle cerebral artery vasculature renders its sampling challenging. Several techniques have been described, ranging from open direct placement of orthogonal subpial depth and strip electrodes through a craniotomy to frame-based stereotactic placement of orthogonal or oblique electrodes using stereo-electroencephalography principles. The authors describe an alternative method for sampling the insula, which involves placing insular depth electrodes along the long axis of the insula through the insular apex following dissection of the sylvian fissure in conjunction with subdural electrodes over the lateral hemispheric/opercular region. The authors report the feasibility, advantages, disadvantages, and role of this approach in investigating pediatric insular-opercular refractory epilepsy. METHODS The authors performed a retrospective analysis of all children (< 18 years old) who underwent invasive intracranial studies involving the insula between 2002 and 2015. RESULTS Eleven patients were included in the study (5 boys). The mean age at surgery was 7.6 years (range 0.5–16 years). All patients had drug-resistant epilepsy as defined by the International League Against Epilepsy and underwent comprehensive noninvasive epilepsy surgery workup. Intracranial monitoring was performed in all patients using 1 parasagittal insular electrode (1 patient had 2 electrodes) in addition to subdural grids and strips tailored to the suspected epileptogenic zone. In 10 patients, extraoperative monitoring was used; in 1 patient, intraoperative electrocorticography was used alone without extraoperative monitoring. The mean number of insular contacts was 6.8 (range 4–8), and the mean number of fronto-parieto-temporal hemispheric contacts was 61.7 (range 40–92). There were no complications related to placement of these depth electrodes. All 11 patients underwent subsequent resective surgery involving the insula. CONCLUSIONS Parasagittal transinsular apex depth electrode placement is a feasible alternative to orthogonally placed open or oblique-placed stereotactic methodologies. This method is safe and best suited for suspected unilateral cases with a possible extensive insular-opercular epileptogenic zone.

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How to Inject Ictal SPECT? From Manual to Automated Injection

10.21203/rs.3.rs-255385/v1 ◽

2021 ◽

Author(s):

Xavier Setoain ◽

Francisco Campos ◽

Antonio Donaire ◽

Maria Mayoral ◽

Andres Perissinotti ◽

...

Keyword(s):

Injection System ◽

Control Group ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Injection Time ◽

Tracer Injection ◽

Ictal Spect ◽

Seizure Focus ◽

Drug Resistant Epilepsy ◽

Automated Injection

Abstract BackgroundSuccessful surgery depends on the accurate localization of epileptogenic zone before surgery. Ictal SPECT is the only imaging modality that allows identification of the ictal onset zone by measuring the regional cerebral blood flow at the time of injection. The main limitations of ictal SPECT in epilepsy are the complex methodology of the tracer injection during a seizure. To overcome these limitations, we present the main features of the first automated injector for ictal SPECT (epijet, LemerPax; La Chapelle -sur-Erdre; France). In this study we compared traditional manual injection with automated injection for ictal SPECT in122 patients with drug-resistant epilepsy. MethodsThe study included 55 consecutive prospective patients with drug-resistant epilepsy undergoing injection with the automated injector. The control group was our retrospective database of a historic pool of 67 patients, injected manually from 2014-2016. Calculated annual exposure/radioactive dose for operators was measured. Injection time, seizure focus localization with ictal SPECT, as well as repeated hospitalizations related to fails injections were compared in these two groups of patients. ResultsThere were no differences in the average injection time with epijet (13 s) compared with the traditional manual injection (14s). The seizure focus was successfully localized with ictal SPECT with epijet in 44/55 (80%) patients and with manual injection in 46/67 (68%) patients (p=0.694). Repeated studies were required in 16/67 (23%) patients in the manual injection group compared to 4 patients (7%) in the epijet group (p=0.022). Calculated annual exposure/dose for operators of 0.39 mSv/year and administered dose error inferior to 5% are other advantages of epijet. ConclusionThe first results using epijet are promising in adjustment of the injection dose, reducing the rate of radiation exposure for patients and nurses, maintaining the same injection time and allowing high SPECT accuracy. These preliminary results support the use of an automated injection system to inject radioactive ictal SPECT doses in epilepsy units.

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Focal Cortical Resection and Hippocampectomy in a Cat With Drug-Resistant Structural Epilepsy

Frontiers in Veterinary Science ◽

10.3389/fvets.2021.719455 ◽

2021 ◽

Vol 8 ◽

Author(s):

Daisuke Hasegawa ◽

Rikako Asada ◽

Yuji Hamamoto ◽

Yoshihiko Yu ◽

Takayuki Kuwabara ◽

...

Keyword(s):

Veterinary Medicine ◽

Epilepsy Surgery ◽

Therapeutic Option ◽

Occipital Cortex ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Naturally Occurring ◽

Alternative Treatment Option ◽

Drug Resistant Epilepsy ◽

The Right

Epilepsy surgery is a common therapeutic option in humans with drug-resistant epilepsy. However, there are few reports of intracranial epilepsy surgery for naturally occurring epilepsy in veterinary medicine. A 12-year-old neutered female domestic shorthair cat with presumed congenital cortical abnormalities (atrophy) in the right temporo-occipital cortex and hippocampus had been affected with epilepsy from 3 months of age. In addition to recurrent epileptic seizures, the cat exhibited cognitive dysfunction, bilateral blindness, and right forebrain signs. Seizures had been partially controlled (approximately 0.3–0.7 seizures per month) by phenobarbital, zonisamide, diazepam, and gabapentin until 10 years of age; however, they gradually became uncontrollable (approximately 2–3 seizures per month). In order to plan epilepsy surgery, presurgical evaluations including advanced structural magnetic resonance imaging and long-term intracranial video-electroencephalography monitoring were conducted to identify the epileptogenic zone. The epileptogenic zone was suspected in the right atrophied temporo-occipital cortex and hippocampus. Two-step surgery was planned, and a focal cortical resection of that area was performed initially. After the first surgery, seizures were not observed for 2 months, but they then recurred. The second surgery was performed to remove the right atrophic hippocampus and extended area of the right cortex, which showed spikes on intraoperative electrocorticography. After the second operation, although epileptogenic spikes remained in the contralateral occipital lobe, which was suspected as the second epileptogenic focus, seizure frequency decreased to <0.3 seizure per month under treatment with antiseizure drugs at 1.5 years after surgery. There were no apparent complications associated with either operation, although the original neurological signs were unchanged. This is the first exploratory study of intracranial epilepsy surgery for naturally occurring epilepsy, with modern electroclinical and imaging evidence, in veterinary medicine. Along with the spread of advanced diagnostic modalities and neurosurgical devices in veterinary medicine, epilepsy surgery may be an alternative treatment option for drug-resistant epilepsy in cats.

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Interictal SEEG resting-state connectivity localizes seizure onset zone and predicts seizure outcome

10.1101/2021.12.30.21268524 ◽

2022 ◽

Author(s):

Haiteng Jiang ◽

Vasileios Kokkinos ◽

Shuai Ye ◽

Alexandra Urban ◽

Anto Bagic ◽

...

Keyword(s):

Information Flow ◽

Resting State ◽

Inhibitory Input ◽

Seizure Outcome ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Seizure Onset ◽

Seizure Onset Zone ◽

Drug Resistant Epilepsy ◽

Resting State Connectivity

Stereotactic-electroencephalography (SEEG) is a common neurosurgical method to localize epileptogenic zone in drug resistant epilepsy patients and inform treatment recommendations. In the current clinical practice, localization of epileptogenic zone typically requires prolonged recordings to capture seizure, which may take days to weeks. Although epilepsy surgery has been proven to be effective in general, the percentage of unsatisfactory seizure outcomes is still concerning. We developed a method to identify the seizure onset zone (SOZ) and predict seizure outcome using short-time resting-state SEEG data. In a cohort of 43 drug resistant epilepsy patients, we estimated the information flow via directional connectivity and inferred the excitation-inhibition ratio from the 1/f power slope. We hypothesized that the antagonism of information flow at multiple frequencies between SOZ and non-SOZ underlying the relatively stable epilepsy resting state could be related to the disrupted excitation-inhibition balance. We found higher excitability in non-SOZ regions compared to the SOZ, with dominant information flow from non-SOZ to SOZ regions, probably reflecting inhibitory input from non-SOZ to prevent seizure initiation. Greater differences in information flow between SOZ and non-SOZ regions were associated with favorable seizure outcome. By integrating a balanced random forest model with resting-state connectivity, our method localized the SOZ with an accuracy of 85% and predicted the seizure outcome with an accuracy of 77% using clinically determined SOZ. Overall, our study suggests that brief resting-state SEEG data can significantly facilitate the identification of SOZ and may eventually predict seizure outcomes without requiring long-term ictal recordings.

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Localization of the Epileptogenic Zone Using Interictal MEG and Machine Learning in a Large Cohort of Drug-Resistant Epilepsy Patients

Frontiers in Neurology ◽

10.3389/fneur.2018.00647 ◽

2018 ◽

Vol 9 ◽

Cited By ~ 5

Author(s):

Ida A. Nissen ◽

Cornelis J. Stam ◽

Elisabeth C. W. van Straaten ◽

Viktor Wottschel ◽

Jaap C. Reijneveld ◽

...

Keyword(s):

Machine Learning ◽

Large Cohort ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Drug Resistant Epilepsy

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SEEG in Polymicrogyria: When and How?

Invasive Studies of the Human Epileptic Brain ◽

10.1093/med/9780198714668.003.0019 ◽

2018 ◽

pp. 246-262

Author(s):

Louis Maillard ◽

Georgia Ramantani

Keyword(s):

Antiepileptic Drug ◽

Epilepsy Surgery ◽

The Other ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Malformations Of Cortical Development ◽

Cortical Areas ◽

Related Drug ◽

Drug Resistant Epilepsy

Polymicrogyria (PMG) is one of the most common malformations of cortical development (MCDs), with epilepsy affecting most patients. PMG-related drug-resistant epilepsy patients can be considered for surgery in well-selected cases. In this context, a comprehensive presurgical evaluation, often including stereo electroencephalography, is warranted to accurately delineate the epileptogenic zone. The heterogeneity of intrinsic epileptogenicity in the PMG, together with the additional or predominant involvement of remote cortical areas, calls for a different strategy in PMG compared with other MCDs, one that is not predominantly MRI- but rather SEEG-oriented. Favourable results in terms of seizure freedom and antiepileptic drug cessation are feasible in a large proportion of patients with unilateral PMG. PMG extent should not exclude the possibility of epilepsy surgery. On the other hand, patients with hemispheric PMG can be excellent hemispherotomy candidates, particularly in the presence of contralateral hemiparesis. Recent findings support early consideration of surgery in PMG-related drug-resistant epilepsy.

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P.042 Safety and efficacy of stereoelectroencephalography in pediatric epilepsy surgery

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/cjn.2019.142 ◽

2019 ◽

Vol 46 (s1) ◽

pp. S25

Author(s):

CA Elliott ◽

K Narvacan ◽

J Kassiri ◽

S Carline ◽

B Wheatley ◽

...

Keyword(s):

Pediatric Epilepsy ◽

Seizure Outcome ◽

Neurogenic Pulmonary Edema ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Presurgical Evaluation ◽

Pediatric Drug ◽

Safety And Efficacy ◽

Drug Resistant Epilepsy

Background: There are few published reports on the safety and efficacy of stereoelectroencephalography (SEEG) in the presurgical evaluation of pediatric drug-resistant epilepsy. Our objective was to describe institutional experience with pediatric SEEG in terms of (1) insertional complications, (2) identification of the epileptogenic zone and (3) seizure outcome following SEEG-tailored resections. Methods: Retrospective review of 29 patients pediatric drug resistant epilepsy patients who underwent presurgical SEEG between 2005 – 2018. Results: 29 pediatric SEEG patients (15 male; 12.4 ± 4.6 years old) were included in this study with mean follow-up of 6.0 ± 4.1 years. SEEG-related complications occurred in 1/29 (3%)—neurogenic pulmonary edema. A total of 190 multi-contact electrodes (mean of 7.0 ± 2.5per patient) were implanted across 30 insertions which captured 437 electrographic seizures (mean 17.5 ± 27.6 per patient). The most common rationale for SEEG was normal MRI with surface EEG that failed to identify the EZ (16/29; 55%). SEEG-tailored resections were performed in 24/29 (83%). Engel I outcome was achieved following resections in 19/24 cases (79%) with 5.9 ± 4.0 years of post-operative follow-up. Conclusions: Stereoelectroencephalography in presurgical evaluation of pediatric drug-resistant epilepsy is a safe and effective way to identify the epileptogenic zone permitting SEEG-tailored resection.

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Seizures Outcome After Stereoelectroencephalography-Guided Thermocoagulations in Malformations of Cortical Development Poorly Accessible to Surgical Resection

Neurosurgery ◽

10.1227/neu.0000000000000723 ◽

2015 ◽

Vol 77 (1) ◽

pp. 9-15 ◽

Cited By ~ 30

Author(s):

Hélène Catenoix ◽

François Mauguière ◽

Alexandra Montavont ◽

Philippe Ryvlin ◽

Marc Guénot ◽

...

Keyword(s):

Seizure Frequency ◽

Low Voltage ◽

Cortical Development ◽

Seizure Outcome ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Seizure Onset ◽

Implanted Electrodes ◽

Spontaneous Seizures ◽

Drug Resistant Epilepsy

Abstract BACKGROUND: Radiofrequency thermocoagulation (RFTC) guided by stereoelectroencephalography (SEEG) has proved to be a safe palliative method to reduce seizure frequency in patients with drug-resistant partial epilepsy. In malformation of cortical development (MCD), increasing the number of implanted electrodes over that needed for mapping of the epileptogenic zone could help to maximize RFTC efficiency. OBJECTIVE: To evaluate the benefit of SEEG-guided RFTC in 14 patients suffering from drug-resistant epilepsy related to MCD located in functional cortical areas or in regions poorly accessible to surgery. METHODS: Ten men and 4 women were treated by RFTC. Thermolesions were produced by applying a 50-V, 120-mA current for 10 to 30 seconds within the epileptogenic zone as identified by the SEEG investigation. RESULTS: An average of 25.8 ± 17.5 thermolesions were made per procedure. The median follow-up after the procedure was 41.7 months. Sixty-four percent of the patients experienced a long-term decrease in seizure frequency of >50%, of whom 6 (43%) presented long-lasting freedom from seizure. When a focal low-voltage fast activity was present at seizure onset on SEEG recordings, 87.5% of patients were responders or seizure free. All of the patients in whom electric stimulation reproduced spontaneous seizures were responders. CONCLUSION: Our results show the good benefit-risk ratio of the SEEG-guided procedure for patients suffering from MCD in whom surgery is risky. This study identifies 2 factors, focal low-voltage, high-frequency activity at seizure onset and lowered epileptogenic threshold in the coagulated area, that could be predictive of a favorable seizure outcome after RFTC.

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Transcriptomic Analysis of the Epileptogenic Zone of Drug Resistant Epilepsy Patients Subjected to Neurosurgery.

IBJ Plus ◽

10.24217/2531-0151.21v1s4.00032 ◽

2021 ◽

Author(s):

◽

...

Keyword(s):

Transcriptomic Analysis ◽

Epileptogenic Zone ◽

Drug Resistant ◽

Drug Resistant Epilepsy

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