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Objectives: Although hemispheric surgeries are among the most effective procedures for drug-resistant epilepsy (DRE) in the pediatric population, there is a large variability in seizure outcomes at the group level. A recently developed HOPS score provides individualized estimation of likelihood of seizure freedom to complement clinical judgement. The objective of this study was to develop a freely accessible online calculator that accurately predicts the probability of seizure freedom for any patient at 1-, 2-, and 5-years post-hemispherectomy., Methods: Retrospective data of all pediatric patients with DRE and seizure outcome data from the original Hemispherectomy Outcome Prediction Scale (HOPS) study were included. The primary outcome of interest was time-to-seizure recurrence. A multivariate Cox proportional-hazards regression model was developed to predict the likelihood of post-hemispheric surgery seizure freedom at three time points (1-, 2- and 5- years) based on a combination of variables identified by clinical judgment and inferential statistics predictive of the primary outcome. The final model from this study was encoded in a publicly accessible online calculator on the International Network for Epilepsy Surgery and Treatment (iNEST) website (https://hops-calculator.com/)., Results: The selected variables for inclusion in the final model included the five original HOPS variables (age at seizure onset, etiologic substrate, seizure semiology, prior non-hemispheric resective surgery, and contralateral fluorodeoxyglucose-positron emission tomography [FDG-PET] hypometabolism) and three additional variables (age at surgery, history of infantile spasms, and magnetic resonance imaging [MRI] lesion). Predictors of shorter time-to-seizure recurrence included younger age at seizure onset, prior resective surgery, generalized seizure semiology, FDG-PET hypometabolism contralateral to the side of surgery, contralateral MRI lesion, non-lesional MRI, non-stroke etiologies, and a history of infantile spasms. The area under the curve (AUC) of the final model was 73.0%., Significance: Online calculators are useful, cost-free tools that can assist physicians in risk estimation and inform joint decision-making processes with patients and families, potentially leading to greater satisfaction. Although the HOPS data was validated in the original analysis, the authors encourage external validation of this new calculator., (© 2023 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Focal Cortical Dysplasia (FCD) is a frequent cause of drug-resistant focal epilepsy in children and young adults. The international FCD classifications of 2011 and 2022 have identified several clinico-pathological subtypes, either occurring isolated, i.e., FCD ILAE Type 1 or 2, or in association with a principal cortical lesion, i.e., FCD Type 3. Here, we addressed the DNA methylation signature of a previously described new subtype of FCD 3D occurring in the occipital lobe of very young children and microscopically defined by neuronal cell loss in cortical layer 4. We studied the DNA methylation profile using 850 K BeadChip arrays in a retrospective cohort of 104 patients with FCD 1 A, 2 A, 2B, 3D, TLE without FCD, and 16 postmortem specimens without neurological disorders as controls, operated in China or Germany. DNA was extracted from formalin-fixed paraffin-embedded tissue blocks with microscopically confirmed lesions, and DNA methylation profiles were bioinformatically analyzed with a recently developed deep learning algorithm. Our results revealed a distinct position of FCD 3D in the DNA methylation map of common FCD subtypes, also different from non-FCD epilepsy surgery controls or non-epileptic postmortem controls. Within the FCD 3D cohort, the DNA methylation signature separated three histopathology subtypes, i.e., glial scarring around porencephalic cysts, loss of layer 4, and Rasmussen encephalitis. Differential methylation in FCD 3D with loss of layer 4 mapped explicitly to biological pathways related to neurodegeneration, biogenesis of the extracellular matrix (ECM) components, axon guidance, and regulation of the actin cytoskeleton. Our data suggest that DNA methylation signatures in cortical malformations are not only of diagnostic value but also phenotypically relevant, providing the molecular underpinnings of structural and histopathological features associated with epilepsy. Further studies will be necessary to confirm these results and clarify their functional relevance and epileptogenic potential in these difficult-to-treat children., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Objective: This study was undertaken to determine whether the vertical parasagittal approach or the lateral peri-insular/peri-Sylvian approach to hemispheric surgery is the superior technique in achieving long-term seizure freedom., Methods: We conducted a post hoc subgroup analysis of the HOPS (Hemispheric Surgery Outcome Prediction Scale) study, an international, multicenter, retrospective cohort study that identified predictors of seizure freedom through logistic regression modeling. Only patients undergoing vertical parasagittal, lateral peri-insular/peri-Sylvian, or lateral trans-Sylvian hemispherotomy were included in this post hoc analysis. Differences in seizure freedom rates were assessed using a time-to-event method and calculated using the Kaplan-Meier survival method., Results: Data for 672 participants across 23 centers were collected on the specific hemispherotomy approach. Of these, 72 (10.7%) underwent vertical parasagittal hemispherotomy and 600 (89.3%) underwent lateral peri-insular/peri-Sylvian or trans-Sylvian hemispherotomy. Seizure freedom was obtained in 62.4% (95% confidence interval [CI] = 53.5%-70.2%) of the entire cohort at 10-year follow-up. Seizure freedom was 88.8% (95% CI = 78.9%-94.3%) at 1-year follow-up and persisted at 85.5% (95% CI = 74.7%-92.0%) across 5- and 10-year follow-up in the vertical subgroup. In contrast, seizure freedom decreased from 89.2% (95% CI = 86.3%-91.5%) at 1-year to 72.1% (95% CI = 66.9%-76.7%) at 5-year to 57.2% (95% CI = 46.6%-66.4%) at 10-year follow-up for the lateral subgroup. Log-rank test found that vertical hemispherotomy was associated with durable seizure-free progression compared to the lateral approach (p = .01). Patients undergoing the lateral hemispherotomy technique had a shorter time-to-seizure recurrence (hazard ratio = 2.56, 95% CI = 1.08-6.04, p = .03) and increased seizure recurrence odds (odds ratio = 3.67, 95% CI = 1.05-12.86, p = .04) compared to those undergoing the vertical hemispherotomy technique., Significance: This pilot study demonstrated more durable seizure freedom of the vertical technique compared to lateral hemispherotomy techniques. Further studies, such as prospective expertise-based observational studies or a randomized clinical trial, are required to determine whether a vertical approach to hemispheric surgery provides superior long-term seizure outcomes., (© 2021 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Background: Nowadays, few surgery analysis has been reported in cases of epilepsy after viral encephalitis(VE). Herein, this study was to evaluate the efficacy of surgery and capability of stereoelectroencephalography (SEEG) in the definition of the epileptogenic zone (EZ) after VE, and also to explore the relationship between the SEEG features and the surgical outcomes., Methods: We retrospectively analyzed 10 surgically treated patients that identified to suffer from epilepsy secondary to VE using SEEG, and investigated the SEEG features associated with surgical outcomes in these patients. Besides visual analysis, we used the epileptogenicity index (EI), a semi-quantitative and supplementary tool to evaluate the validity of SEEG in the context of VE., Results: Among the 10 operated patients, 3 of them became completely seizure-free. The patients who got totally seizure free or significant improvement, the seizure onset was located either in the antero-mesial temporal structures or focal gyrus; patients who got worthwhile improvement or no improvement, the seizure started from multiple brain lobes. The number of electrodes classified as epileptogenic visually involved were closely correlated with EI positive onses.Anatomic areas defined and shown as EZ on MRI by visual assessment were also defined as epileptogenic by the EI in these cases., Conclusion: Apart from exploring the surgical outcome related to epilepsy after VE, we also bring insight into the relationship between the SEEG features and surgical outcome with the application of the supplementary methods.

Objective: To investigate the clinical value of stereo-electroencephalography guided radiofrequency thermos-coagulation (RFTC) in drug resistant temporal epilepsy. Methods: The clinical data of 12 patients with refractory temporal epilepsy who underwent implantation of SEEG electrodes and radiofrequency thermos-coagulation from July 2016 to November 2017 were analysed retrospectively. Results: The mean follow-up time was 6.4±4.6 months after thermos-coagulation, and 10.2±3.5 months after resection. Engel Ⅰa was observed in 9 cases, with Ⅱa, Ⅲa and Ⅳa 1 cases respectively. Nine patients experienced a ≥50% decrease of seizure frequency after RFTC (R+ , 75%), of whom one had got a sustained seizure free for 15 months and the other with decrease of seizure frequency by over 90% for 14 months. There was a statistical significance in seizure frequency between pre- and post-thermo-coagulation ( P =0.008). Ten cases underwent open surgery following SEEG-guided RFTC, of them 8 cases got seizure free. RFTC was effective in 6 of 8 cases. In our group, all patients have not suffered from any neurologic and cognitive deficiency, and even several patients have some improvements on memory quotient. Conclusions: Although it is less effective than resective surgery, SEEG-guided RFTC can be a relatively safe, effective treatment because of its precision and minimal invasion for patients with complex drug resistant temporal epilepsy, especially for impossible any cortical resection. In addition, its effect may be a predictor of outcome after conventional cortectomy.

Objective: In 2011, the International League Against Epilepsy (ILAE) proposed a consensus classification system of focal cortical dysplasia (FCD) to distinguish clinicopathological subtypes, for example, "isolated" FCD type Ia-c and IIa-b, versus "associated" FCD type IIIa-d. The histopathological differentiation of FCD type I and III variants remains, however, a challenging issue in everyday practice. We present a unique histopathological pattern in patients with difficult-to-diagnose FCD, which highlights this dilemma, but also helps to refine the current ILAE classification scheme of FCD., Methods: We present a retrospective series of 11 male and one female patient with early onset pharmacoresistant epilepsy of the posterior quadrant (mean age at seizure onset = 4.6 years). All surgical specimens were reviewed. Clinical histories were retrieved and extracted from archival patient files., Results: Microscopic inspection revealed abnormalities in cortical architecture with complete loss of layer 4 in all surgical samples of the occipital lobe, as confirmed by semiquantitative measurements (p < 0.01). Clinical history reported early transient hypoxic condition in nine patients (75%). Magnetic resonance imaging (MRI) revealed abnormal signals in the occipital lobe in all patients, and signal changes suggestive of subcortical encephalomalacia were found in seven patients. Surgical treatment achieved favorable seizure control (Engel class I and II) in seven patients with an available follow-up period of 6.1 years., Significance: Prominent disorganization of cortical layering and lack of any other microscopically visible principle lesion in the surgical specimen would result in this neuropathological pattern hitherto being classified as FCD ILAE type Ib. However, perinatal hypoxia with distinctive MRI changes suggested primarily a hypoxemic lesion and acquired pathomechanism of neuronal cell loss in the occipital lobe of our patient series. We propose, therefore, classifying this distinctive clinicopathological pattern as a separate variant of FCD ILAE type IIId., (Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.)

Objective: Insular and opercular cortex is involved in complicated physiological function.Insular seizures involve extensive epileptic network, which results in the complex and diverse semiology.Electrical cortical stimulation(ECS) can explore the functional mapping and symptomatogenic zone., Methods: The clinical presurgical evaluation and ECS data of 20 patients whose electrode contacts were located in the insular and opercular were analyzed retrospectively.CT scan/3D MRI data fusion was performed in order to accurately identify and locate each contact and check the electrode trajectory by the MRI images performed after the electrodes were removed.ECS was applied between two contiguous contacts.Stimulation usually lasted for 5 s at 50 Hz(pulse width=0.3 ms). Depending on the area of stimulated cortex, the stimulation intensities ranged from 0.2 to 3.0 mA.The classification of the insular were anterior short gyrus, middle short gyrus, precentral gyrus, postcentral gyrus, posterior long gyrus and insular pole.The classification of the opercular were orbital, frontal, precentral, central, parietal and temporal opercular., Results: One hundred and six contacts were located in the insular and 51 responses were evoked (48.11%). Four hundred eighteen contacts were located in the insular and 132 responses were evoked (31.58%). We classified the principal responses as somatosensory, pain, auditory, oropharyngeal, speech disturbances and neurovegetative response.Somatosensory responses were mainly evoked in parietal opercular and postcentral gyrus, while pain response distributed sporadically.Auditory were only evoked in temporal opercular(transverse temporal gyri) and posterior long gyrus.Oropharyngeal symptoms were only evoked in central opercular.Speech disturbances were located in precentral and central opercular and neurovegetative responses were mainly evoked in insular pole and middle short gyrus., Conclusions: These findings may indicate a functional specificity for the insular gyrus and opercular, which contribute to the understanding of anatomo-functional organization and the role in insular and opercular epileptic network.Moreover, it could optimize the implantation strategy for exploring these structures.

Sturge-Weber syndrome (SWS) is a rare syndrome characterized by capillary-venous malformations involving skin and brain. Many patients with SWS also suffer from drug-resistant epilepsy. We retrospectively studied a series of six SWS patients with epilepsy and extensive neurosurgical resections. At time of surgery, the patients' age ranged from 11 to 35 years (with a mean of 20.2 years). All surgical specimens were well preserved, which allowed a systematic microscopical inspection utilizing the 2011 ILAE classification for focal cortical dysplasia (FCD). Neuropathology revealed dysmorphic-like neurons with hypertrophic cell bodies reminiscent to those described for FCD type IIa in all cases. However, gross architectural abnormalities of neocortical layering typical for FCD type IIa were missing, and we propose to classify this pattern as FCD ILAE type IIIc. In addition, our patients with earliest seizure onset also showed polymicrogyria (PMG; n = 4). The ictal onset zones were identified in all patients by subdural electrodes, and these areas always showed histopathological evidence for FCD type IIIc. Four out of five patients had favorable seizure control after surgery with a mean follow-up period of 1.7 years. We concluded from our study that FCD type IIIc and PMG are frequently associated findings in SWS. FCD type IIIc may play a major epileptogenic role in SWS and complete resection of the associated FCD should be considered a prognostic key factor to achieve seizure control., (© 2014 International Society of Neuropathology.)

Objective: To investigate the clinicopathologic features of the brain tissue diagnosed as ulegyria from modified anatomic hemispherectomy for refractory epilepsy., Methods: The clinical and pathologic findings were reviewed in 39 patients who underwent modified anatomic hemispherectomy and diagnosed as ulegyria in the Epilepsy Center of Tsinghua University Yuquan Hospital from 2007 to 2011., Results: All patients including 30 males and 9 females had medically intractable seizures, and the mean age of seizure onset and disease duration were 4.0 years and 7.3 years respectively. Significant history included febrile seizure in 14 patients (35.9%), cerebral hemorrhage in 8 patients (20.5%), fetal distress and surgical trauma each in 6 patients (15.4%), vascular malformation and cerebral hemorrhage in 1 patient (2.6%), and unclear history in 4 patients (10.2%). Histologically, all cases were characterized by cortical destruction, with neuronal loss and gliosis. All cases were accompanied by varying degree of cortical dysplasia, which were diagnosed as focal cortical dysplasia IIId. Hippocampus sclerosis was identified in 2 cases. Seizure outcome after surgery revealed 37 patients (94.9%) had an Engel grade I, two patients (5.1%) had an Engel grade II., Conclusions: Febrile seizure, cerebral hemorrhage, fetal distress and surgical trauma in childhood can lead to refractory epilepsy. Histopathological change in the brain is ulegyria accompanied by focal cortical dysplasia IIId. Modified anatomic hemispherectomy is an effective therapy to treat those patients with extensive changes of one hemisphere.

Objective: To localize the sensory motor cortex of human brain by analyzing the power change in Gamma band (> 60 Hz) of electrocorticography (ECoG) data., Methods: Eight patients with intractable epilepsy underwent temporary placement of subdural electrodes. After surgery, sensory evoked potential (SEP), electrocortical stimulation (CES) and event-related synchronization analysis of Gamma band (Gamma ERS analysis) were performed to reduce the risk of complications. The results of Gamma ERS analysis were compared with those of SEP and CES., Results: The results of Gamma ERS analysis had 80.7% electrodes fitting perfectly those of CES and SEP. And the percentage reached 92.3% if electrodes were superimposed or added adjacently., Conclusion: The Gamma ERS analysis is a new sensitive and precise method for cortical function mapping.