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Introduction: Pediatric epilepsy surgery is an effective treatment modality for patients with drug-resistant epilepsy (DRE). Early pediatric surgery yields favorable results for DRE in terms of seizure control and neurophysiological outcome. In this study, pediatric patients were categorized based on their age (above 3 years old and below 3 years old) to demonstrate the effectiveness and safety of surgical procedures., Methods: In this retrospective, single-center study, 60 pediatric patients who underwent epilepsy surgery at Istanbul Faculty of Medicine between 2002 and 2018 were evaluated. Overall morbidity and mortality rates, as well as seizure outcomes of the patients, were assessed and compared based on two age groups: those aged 3 years old or younger and those older than 3 years old. The effectiveness of invasive monitoring was also evaluated in relation to pathological results. The postoperative seizure outcome rates were evaluated using Engel's classification, with an average follow-up period of 8.7 years., Results: Out of the total number of patients, 47 (78.4%) underwent resective surgery, while 13 (21.6%) had palliative surgery. Ten patients (16.6%) had invasive monitoring. Among all patients, 34 were classified as Engel I and II (56.6%), while 26 were classified as Engel III and IV (43.4%) postoperatively. 47% of patients who were under 3 years old, 60.4% of patients who were over 3 years old, and 50% of patients who underwent invasive monitoring had a favorable seizure outcome (Engel I-II). Postoperative morbidity and mortality rates were 35% (n = 21) and 1.6% (n = 1), respectively., Conclusion: Pediatric epilepsy surgery is an important treatment modality for preserving cognitive abilities and providing effective treatment for pediatric DRE. In our study, we claim that both invasive monitoring and epilepsy surgery lead to favorable seizure outcomes for all age groups. Further clinical studies should be conducted to provide more reliable data on the safety and effectiveness of the surgery, particularly in patients under the age of three., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Objective: In the histopathological examination of treatment-resistant epilepsy, focal cortical dysplasia (FCD) is the most common diagnosis in the pediatric group. FCD is classified histopathologically according to the International League Against Epilepsy (ILAE) classification. In the last decade since the ILAE classification has been released, molecular genetic studies have revealed mTOR pathway-related mutations as a major etiology. The objective of this study was to determine the incidence of FCD in treatment-resistant epilepsy patients, explore histomorphological and immunohistochemical features, examine clinicopathological correlation, demonstrate mTOR pathway activation using a pS6 antibody immunohistochemically, and try to introduce a candidate for possible targeted therapies., Methods: Paraffin blocks and slides of tissue from patients with treatment-resistant epilepsy were reexamined retrospectively. Histopathological subtypes of FCD were determined according to the ILAE classification. NeuN and neurofilament H (NF-H) staining were performed, and additionally a pS6 antibody was used to demonstrate mTOR pathway activation., Results: In 32 cases diagnosed with FCD, or 17.5% of 183 surgical epilepsy materials, there were no significant differences in the statistical analysis of clinical variables between the ILAE FCD subtypes. Recommended antibody NeuN revealed microcolumnar alignment in the FCD type Ia and IIIa groups and the loss of lamination in the type Ib group. Another recommended antibody, NF-H, was not found to be useful in discriminating between normal and dysmorphic neurons. pS6 expression, showing mTOR pathway activation, was observed in dysmorphic neurons and balloon cells in all FCD type II cases., Conclusions: Significant pS6 expression in FCD type II represents the genomic nature of the disease noted in the literature. Nevertheless, the known MTOR gene and mTOR pathway-related mutations remain behind proportionally to explain the mTOR pathway activation in all FCD type II cases. Clinicopathologically and genetically integrated classification and usage of mTOR pathway inhibitors in treatment are expected as a recent evolution.

High-frequency oscillations in local field potentials recorded with intracranial EEG are putative biomarkers of seizure onset zones in epileptic brain. However, localized 80-500 Hz oscillations can also be recorded from normal and non-epileptic cerebral structures. When defined only by rate or frequency, physiological high-frequency oscillations are indistinguishable from pathological ones, which limit their application in epilepsy presurgical planning. We hypothesized that pathological high-frequency oscillations occur in a repetitive fashion with a similar waveform morphology that specifically indicates seizure onset zones. We investigated the waveform patterns of automatically detected high-frequency oscillations in 13 epilepsy patients and five control subjects, with an average of 73 subdural and intracerebral electrodes recorded per patient. The repetitive oscillatory waveforms were identified by using a pipeline of unsupervised machine learning techniques and were then correlated with independently clinician-defined seizure onset zones. Consistently in all patients, the stereotypical high-frequency oscillations with the highest degree of waveform similarity were localized within the seizure onset zones only, whereas the channels generating high-frequency oscillations embedded in random waveforms were found in the functional regions independent from the epileptogenic locations. The repetitive waveform pattern was more evident in fast ripples compared to ripples, suggesting a potential association between waveform repetition and the underlying pathological network. Our findings provided a new tool for the interpretation of pathological high-frequency oscillations that can be efficiently applied to distinguish seizure onset zones from functionally important sites, which is a critical step towards the translation of these signature events into valid clinical biomarkers.awx374media15721572971001. [ABSTRACT FROM AUTHOR]