Seizure and cognitive outcomes after resection of glioneuronal tumors in children

How Cancer Harms the Developing Brain: Long-Term Outcomes in Pediatric Cancer Survivors

Survival rates for pediatric cancer are improving, resulting in a rising need to understand and address long-term sequelae. In this narrative review, we summarize the effects of cancer and its treatment on the developing brain, with a focus on neurocognitive function in leukemia and pediatric brain tumor survivors. We then discuss possible mechanisms of brain injury and management considerations.

Predictive factors for seizure freedom after epilepsy surgery for pediatric low-grade tumors and focal cortical dysplasia

Epilepsy may be drug-resistant in a third of patients necessitating alternative treatments, such as surgery. Among refractory epilepsy patients, the most common etiologies are tumors and focal cortical dysplasia (FCD). Surgical management of tumor-related epilepsy has one of the highest rates of seizure freedom, whereas FCD represents some of the lowest success rates in epilepsy treatment. This study investigates the pre-operative characteristics associated with differences in postsurgical seizure outcomes in patients with FCD and tumors. We completed a retrospective cross-sectional review of epilepsy surgery patients with tumors (n = 29) or FCD (n = 44). Participants had a minimum medical follow-up at least 6 months after surgery (FCD M = 2.1 years; Tumors M = 2.0 years). Patients with FCD trended toward an earlier age of onset (t = -4.19, p = 0.058) and longer epilepsy duration (t = 3.75, p < 0.001). Epilepsy surgery is highly effective in reducing seizures in patients with FCD or tumors with over 70 % of all patients achieving seizure freedom. We found a higher rate of seizure freedom in patients with tumors than FCD, but this difference did not reach significance (79 vs. 66 %). Predictive factors of outcomes for FCD and tumors differ. Findings indicate that diagnostic tests may be differentially sensitive to patients with tumors, and future research is needed.

Long-term seizure outcome after epilepsy surgery of neuroglial tumors

Purpose

Neuroglial tumors are frequently associated with pharmacorefractory epilepsies. However, comprehensive knowledge about long-term outcomes after epilepsy surgery and the main prognostic factors for outcome is still limited. We sought to evaluate long-term outcomes and potential influencing factors in a large cohort of patients who underwent surgery for neuroglial tumors in a single-center setting.

Methods

The study analyzed the outcomes of 107 patients who underwent epilepsy surgery for neuroglial tumors between 2001 and 2020 at the Department of Epileptology, University Hospital Bonn, in Germany. The outcomes were evaluated using Engel classification. Differences in outcome related to potential prognostic factors were examined using the Chi2-test, Fisher's exact test and sign test. Additionally, stepwise logistic regression analysis was employed to identify independent prognostic factors.

Results

Complete seizure freedom (Engel Class IA) was achieved in 75% of the operated patients at 12 months, and 56% at the last follow-up visit (70.4 ± 6.2 months, median: 40 months). Completeness of resection was a crucial factor for both 12-month follow-up outcomes and the longest available outcomes, whereas lobar tumor localization, histology (ganglioglioma vs. dysembryoplastic neuroepithelial tumor), history of bilateral tonic-clonic seizures prior to surgery, invasive diagnostics, side of surgery (dominant vs. non-dominant hemisphere), age at epilepsy onset, age at surgery, and epilepsy duration did not consistently impact postsurgical outcomes. Among temporal lobe surgeries, patients who underwent lesionectomy and lesionectomy, including hippocampal resection, demonstrated similar outcomes.

Conclusion

Neuroglial tumors present as excellent surgical substrates in treating structural epilepsy. To achieve an optimal postsurgical outcome, a complete lesion resection should be pursued whenever possible.

The clinical, imaging, pathological and genetic landscape of bottom-of-sulcus dysplasia

Bottom-of-sulcus dysplasia (BOSD) is increasingly recognized as a cause of drug-resistant, surgically-remediable, focal epilepsy, often in seemingly MRI-negative patients. We describe the clinical manifestations, morphological features, localization patterns and genetics of BOSD, with the aims of improving management and understanding pathogenesis. We studied 85 patients with BOSD diagnosed between 2005-2022. Presenting seizure and EEG characteristics, clinical course, genetic findings and treatment response were obtained from medical records. MRI (3 T) and 18F-FDG-PET scans were reviewed systematically for BOSD morphology and metabolism. Histopathological analysis and tissue genetic testing were performed in 64 operated patients. BOSD locations were transposed to common imaging space to study anatomical location, functional network localization and relationship to normal MTOR gene expression. All patients presented with stereotyped focal seizures with rapidly escalating frequency, prompting hospitalization in 48%. Despite 42% patients having seizure remissions, usually with sodium channel blocking medications, most eventually became drug-resistant and underwent surgery (86% seizure-free). Prior developmental delay was uncommon but intellectual, language and executive dysfunction were present in 24%, 48% and 29% when assessed preoperatively, low intellect being associated with greater epilepsy duration. BOSDs were missed on initial MRI in 68%, being ultimately recognized following repeat MRI, 18F-FDG-PET or image postprocessing. MRI features were grey-white junction blurring (100%), cortical thickening (91%), transmantle band (62%), increased cortical T1 signal (46%) and increased subcortical FLAIR signal (26%). BOSD hypometabolism was present on 18F-FDG-PET in 99%. Additional areas of cortical malformation or grey matter heterotopia were present in eight patients. BOSDs predominated in frontal and pericentral cortex and related functional networks, mostly sparing temporal and occipital cortex, and limbic and visual networks. Genetic testing yielded pathogenic mTOR pathway variants in 63% patients, including somatic MTOR variants in 47% operated patients and germline DEPDC5 or NPRL3 variants in 73% patients with familial focal epilepsy. BOSDs tended to occur in regions where the healthy brain normally shows lower MTOR expression, suggesting these regions may be more vulnerable to upregulation of MTOR activity. Consistent with the existing literature, these results highlight (i) clinical features raising suspicion of BOSD; (ii) the role of somatic and germline mTOR pathway variants in patients with sporadic and familial focal epilepsy associated with BOSD; and (iii) the role of 18F-FDG-PET alongside high-field MRI in detecting subtle BOSD. The anatomical and functional distribution of BOSDs likely explain their seizure, EEG and cognitive manifestations and may relate to relative MTOR expression.

Clinical characteristics and surgical outcomes of low-grade epilepsy-associated brain tumors

Background

Low-grade epilepsy-associated brain tumors (LEATs) are found to be the second most common lesion-related epilepsy. Malignant potential of LEATs is very low and the overall survival is good, so the focus of treatment is focused more on seizure outcome rather than oncological prognosis.

Objectives

This study was conducted to evaluate the risk factors of seizure outcomes after resection in patients with LEATs.

Design

A retrospective study.

Methods

A retrospective analysis of patients with LEATs who underwent resective surgery in our three epilepsy centers between October 2010 and April 2023 with a minimum follow-up of 1 year. Demography, clinical characters, neurophysiology, and molecular neuropathology were assessed for association with postoperative seizure outcomes at 1-, 2-, and 5-year follow-up. Synthetic minority oversampling technique (SMOTE) algorithm model was performed to handle the imbalance of data distribution. Gaussian Naïve Bayes (GNB) algorithms were created as a basis for classifying outcomes according to observation indicators.

Results

A total of 111 patients were enrolled in the cohort. The most common pathology was ganglioglioma (n = 37, 33.3%). The percentage of patients with seizure freedom was 91.0% (101/111) at 1-year follow-up, 87.5% (77/88) at 2-year follow-up, and 79.1% (53/67) at 5-year follow-up. Partial resection had a significantly poor seizure outcome compared to total resection and supratotal resection (p < 0.05). The epileptiform discharge on post-resective intraoperative electrocorticography (ECoG) or postoperative scalp electroencephalography (EEG) were negative factors on postoperative seizure freedom at 1-, 2-, or 5-year follow-ups (p < 0.05). The area under the receiver-operating characteristic curve value of the GNB-SMOTE model was 0.95 (95% CI, 0.876-1.000), 0.892 (95% CI, 0.656-0.934), and 0.786 (95% CI, 0.491-0.937) at 1-, 2-, and 5-year follow-up, respectively.

Conclusion

The partial resection, post-resective intraoperative ECoG, and postoperative scalp EEG were valuable indicators of poor seizure outcomes. The utilization of post-resective intraoperative ECoG is beneficial to improve seizure outcomes. Based on the data diversity and completeness of three medical centers, a multivariate correlation analysis model was established based on GNB algorithm.

Patient, parent and carer perspectives surrounding expedited paediatric epilepsy surgery

OBJECTIVE

Most paediatric epilepsies with MRI visible lesions do not respond to antiseizure pharmacotherapy. Such medication resistance, which often takes years to become formally defined, is commonly required for surgical candidacy. Expedited surgical referral at lesional epilepsy diagnosis may result in better seizure, cognitive and developmental prognoses. This study explored the views of patients, parents and carers regarding epilepsy surgery, treatment priorities, and participation in a proposed expedited surgery trial.

METHODS

205 patients, parents and carers (61% UK-based, 26% North American) responded to electronic surveys from February to May 2022. Participants were recruited through social media sites, epilepsy charities and societies. Categorical choice and free-text questions were used to investigate participant perspectives, and Pearson's chi-squared test was utilised to detect meaningful differences amongst respondent subgroups.

RESULTS

Almost 90% of respondents who had experienced epilepsy surgery (either themselves or their child) reported seizure cessation or reduction. Postoperative outcome measures prioritised most frequently were seizure freedom (66%), quality of life (47%), seizure severity (30%), seizure frequency (28%) and independence (27%). Most participants support expedited surgery in suitable patients (65%), with just over half (51%) willing to participate in the proposed trial. Many participants (37%) were undecided, often due to fears surrounding neurosurgery. Subgroup perspectives were broadly similar, with more parents and caregivers favouring expedited surgery compared to patients (p = .016) and more UK-based participants willing to take part in an expedited surgery trial compared to those from North America (p = .01).

CONCLUSIONS

Patients, parents and carers are open to considering expedited surgery for lesional epilepsies and would support a trial exploring this approach. Priorities from treatment were largely similar between participant subgroups, with seizure, quality of life and neuropsychological outcomes ranked highly. Accounting for these preferences will facilitate the delivery of a trial that is patient- and caregiver-focused, enhancing feasibility, satisfaction and benefit for prospective participants.

Long-term epilepsy associated-tumors (LEATs): what is new?

Long-term epilepsy-associated tumors (LEATs) include a series of neoplasms that commonly occur in children, adolescents, or young adults, have an astrocytic or glioneuronal lineage, are histologically benign (WHO grade1) with a neocortical localization predominantly situated in the temporal lobes. Clinically, chronic refractory epilepsy is usually the unique symptom. Gangliogliomas (GG) and dysembryoplastic neuroepithelial tumors (DNT) are the most common representative entities besides pilocytic astrocytomas (PA) and angiocentric gliomas (AG). Recent molecular studies have defined new clinicopathological entities, which are recognized by the WHO 2021 classification of brain tumors. Some of them such as diffuse astrocytoma MIB or MYBL1 altered, polymorphous low-grade neuroepithelial tumor of the young (PLNTY), and multilocular and vacuolating neuronal tumor (MVNT) are currently considered LEATs. The relationship between LEATs and epilepsy is still a matter of debate, and there is a general agreement about the beneficial effects of an early neurosurgical intervention on the clinical outcome.

Clinician views regarding early surgery for paediatric epilepsy

OBJECTIVE

Many children with lesional epilepsies progress to drug resistance, a criterion required for surgical referral. Expedited surgery may reduce exposure of the developing brain to uncontrolled seizures, improving cognitive outcomes. Designing a trial comparing early surgery with standard care necessitates input from specialist clinicians regarding feasibility and measurable outcomes, which this study investigated.

METHODS

Online surveys were disseminated from June-July 2022 via regional paediatric epilepsy networks and professional societies. 51 UK clinicians responded, mostly paediatricians, paediatric neurologists and epilepsy specialist nurses. Candidacy for epilepsy surgery, outcome measures and support for the proposed study were surveyed. Clinician views were compared by speciality, using Pearson's chi-squared tests to explore differences.

RESULTS

76-98 % of clinicians would refer children for presurgical evaluation at/before drug resistance development across four subgroups (those younger/older than two years, and those with/without a detectable lesion). Earlier referral, at/before epilepsy diagnosis, was considered mostly in those with visible lesions (53 %) and those under two years (31 %). 73 % would consider early surgery before drug resistance is established. Top outcomes to measure were seizure freedom (39 %) and quality of life (22 %). Views of paediatric neurologists and paediatricians did not differ (p > .05).

SIGNIFICANCE

Clinician opinions generally aligned with published guidance regarding epilepsy surgery referral. Some remain cautious to refer young children with lesions prior to trialling more than one antiseizure medication. Most support early surgery in appropriate patients, with seizure and quality of life outcomes rated highly. Incorporating these perspectives will aid future trial design, recruitment and clinical utility.

Cognitive and Behavioral Outcome of Pediatric Low-Grade Central Nervous System Tumors Treated Only with Surgery: A Single Center Experience

BACKGROUND

The present mono-institutional report aimed to describe the cognitive and behavioral outcomes of low-grade central nervous system (CNS) tumors in a cohort of children treated exclusively with surgical intervention.

METHODS

Medical records from 2000-2020 were retrospectively analyzed. We included 38 children (mean age at first evaluation 8 years and 3 months, 16 females) who had undergone presurgical cognitive-behavioral evaluation and/or at least 6 months follow-up. Exclusion criteria were a history of traumatic brain injury, stroke, cerebral palsy or cancer-predisposing syndromes.

RESULTS

The sample presented cognitive abilities and behavioral functioning in the normal range, with weaknesses in verbal working memory and processing speed. The obtained results suggest that cognitive and behavioral functioning is related to pre-treatment variables (younger age at symptoms' onset, glioneuronal histological type, cortical location with preoperative seizures), timing of surgery and seizure control after surgery, and is stable when controlling for a preoperative cognitive and behavioral baseline. Younger age at onset is confirmed as a particular vulnerability in determining cognitive sequelae, and children at older ages or at longer postsurgical follow-up are at higher risk for developing behavioral disturbances.

CONCLUSIONS

Timely treatment is an important factor influencing the global outcome and daily functioning of the patients. Preoperative and regular postsurgical cognitive and behavioral assessment, also several years after surgery, should be included in standard clinical practices.

Low-grade epilepsy-associated neuroepithelial tumors: Tumor spectrum and diagnosis based on genetic alterations

Brain tumors can always result in seizures when involving the cortical neurons or their circuits, and they were found to be one of the most common etiologies of intractable focal seizures. The low-grade epilepsy-associated neuroepithelial tumors (LEAT), as a special group of brain tumors associated with seizures, share common clinicopathological features, such as seizure onsets at a young age, a predilection for involving the temporal lobe, and an almost benign course, including a rather slow growth pattern and thus a long-term history of seizures. Ganglioglioma (GG) and dysembryoplastic neuroepithelial tumor (DNET) are the typical representatives of LEATs. Surgical treatments with complete resection of tumors and related epileptogenic zones are deemed the optimal way to achieve postoperative seizure control and lifetime recurrence-free survival in patients with LEATs. Although the term LEAT was originally introduced in 2003, debates on the tumor spectrum and the diagnosis or classification of LEAT entities are still confusing among epileptologists and neuropathologists. In this review, we would further discuss these questions, especially based on the updated classification of central nervous system tumors in the WHO fifth edition and the latest molecular genetic findings of tumor entities in LEAT entities.

Long-Term Seizure Outcomes and Predictors in Patients with Dysembryoplastic Neuroepithelial Tumors Associated with Epilepsy

OBJECTIVE

To determine the predictors and the long-term outcomes of patients with seizures following surgery for dysembryoplastic neuroepithelial tumors (DNTs); Methods: Clinical data were collected from medical records of consecutive patients of the Department of Neurosurgery of Sanbo Brain Hospital of Capital Medical University with a pathological diagnosis of DNT and who underwent surgery from January 2008 to July 2021. All patients were followed up after surgery for at least one year. We estimated the cumulative rate of seizure recurrence-free and generated survival curves. A log-rank (Mantel-Cox) test and a Cox proportional hazard model were performed for univariate and multivariate analysis to analyze influential predictors; Results: 63 patients (33 males and 30 females) were included in this study. At the final follow-up, 49 patients (77.8%) were seizure-free. The cumulative rate of seizure recurrence-free was 82.5% (95% confidence interval (CI) 71.8-91.3%), 79.0% (95% CI 67.8-88.6%) and 76.5% (95% CI 64.8-87.0%) at 2, 5, and 10 years, respectively. The mean time for seizure recurrence-free was 6.892 ± 0.501 years (95% CI 5.91-7.87). Gross total removal of the tumor and a short epilepsy duration were significant predictors of seizure freedom. Younger age of seizure onset, bilateral interictal epileptiform discharges, and MRI type 3 tumors were risk factors for poor prognosis; Conclusions: A favorable long-term seizure outcome was observed for patients with DNT after surgical resection. Predictor analysis could effectively guide the clinical work and evaluate the prognosis of patients with DNT associated with epilepsy.

The long-term surgical outcomes of low-grade epilepsy-associated neuroepithelial tumors

OBJECTIVE

This study aimed to evaluate the surgical outcomes and relevant prognostic factors in patients with low-grade epilepsy-associated neuroepithelial tumors (LEAT) and, especially, to develop a scoring system to predict postoperative seizure outcomes.

METHODS

The clinical data of patients who underwent epilepsy surgery for LEAT were retrospectively studied. The surgical outcomes of seizure and neurological statuses in patients were evaluated using Engel classification and modified Rankin Scale (mRS) scoring, respectively. A scoring system of seizure outcomes was constructed based on the weight of the β-coefficient estimate of each predictor in the final multivariate predicting model of seizure outcomes.

RESULTS

Of the 287 patients (106 female) enrolled, the median age was 19 years at surgery and 10 years at seizure onset, with a median duration of epilepsy of 60 months. Among 258 patients who were followed up for at least 12 months, 215 (83.3%) patients had a favorable seizure outcome (Engel class I) after surgery, and 43 (16.7%) patients had an unfavorable seizure outcome; longer duration of epilepsy, discordant magnetoencephalography (MEG) findings, and acute postoperative seizures were significantly included in the scoring system to predict unfavorable seizure outcomes, and in the scoring system, accumulated scoring of 0-19 scores was recorded, which were finally grouped into three risk levels: low risk (risk < 30%), medium risk (30% ≤ risk < 70%), and high risk (risk ≥ 70%). In addition, favorable neurological outcomes (mRS score 0-1) were recorded in 187 (72.5%) patients, while unfavorable neurological outcomes were recorded in 71 (27.5%) patients, which were significantly related to poor seizure control, older age at surgery, and longer duration of epilepsy and hospitalization time.

SIGNIFICANCE

The long-term surgical outcomes of LEAT after surgery were satisfactory. A scoring system for predicting unfavorable seizure outcomes with different risk levels was developed, which could partly guide clinical treatments of LEAT.

Early Epilepsy Surgery in Benign Cerebral Tumors: Avoid Your ‘Low-Grade’ Becoming a ‘Long-Term’ Epilepsy-Associated Tumor

Epilepsy surgery in low-grade epilepsy-associated neuroepithelial tumors (LEAT) is usually evaluated in drug-resistant cases, often meaning a time delay from diagnosis to surgery. To identify factors predicting good postoperative seizure control and neuropsychological outcome, the cohort of LEAT patients treated with resective epilepsy surgery at the Epilepsy Center Frankfurt Rhine-Main, Germany between 2015 and 2020 was analyzed. Thirty-five patients (19 males (54.3%) and 16 females, aged 4 to 40 years (M = 18.1), mean follow-up 33 months) were included. Following surgery, 77.1% of patients remained seizure-free (Engel IA/ILAE 1). Hippocampus and amygdala resection was predictive for seizure freedom in temporal lobe epilepsy. In total, 65.7% of all patients showed cognitive deficits during presurgical workup, decreasing to 51.4% after surgery, predominantly due to significantly less impaired memory functions (p = 0.011). Patients with presurgical cognitive deficits showed a tendency toward a longer duration of epilepsy (p = 0.050). Focal to bilateral tonic-clonic seizures (p = 0.019) and young age at onset (p = 0.018) were associated with a higher likelihood of cognitive deficits after surgery. Therefore, we advocate early epilepsy surgery without requiring proof of drug-resistance. This refers especially to lesions associated with the non-eloquent cortex.

The genomic landscape of dysembryoplastic neuroepithelial tumours and a comprehensive analysis of recurrent cases

AIMS

Dysembryoplastic neuroepithelial tumour (DNT) is a glioneuronal tumour that is challenging to diagnose, with a wide spectrum of histological features. Three histopathological patterns have been described: specific DNTs (both the simple form and the complex form) comprising the specific glioneuronal element, and also the non-specific/diffuse form which lacks it, and has unclear phenotype-genotype correlations with numerous differential diagnoses.

METHODS

We used targeted methods (immunohistochemistry, fluorescence in situ hybridisation and targeted sequencing) and large-scale genomic methodologies including DNA methylation profiling to perform an integrative analysis to better characterise a large retrospective cohort of 82 DNTs, enriched for tumours that showed progression on imaging.

RESULTS

We confirmed that specific DNTs are characterised by a single driver event with a high frequency of FGFR1 variants. However, a subset of DNA methylation-confirmed DNTs harbour alternative genomic alterations to FGFR1 duplication/mutation. We also demonstrated that a subset of DNTs sharing the same FGFR1 alterations can show in situ progression. In contrast to the specific forms, "non-specific/diffuse DNTs" corresponded to a heterogeneous molecular group encompassing diverse, newly-described, molecularly distinct entities.

CONCLUSIONS

Specific DNT is a homogeneous group of tumours sharing characteristics of paediatric low-grade gliomas: a quiet genome with a recurrent genomic alteration in the RAS-MAPK signalling pathway, a distinct DNA methylation profile and a good prognosis but showing progression in some cases. The "non-specific/diffuse DNTs" subgroup encompasses various recently described histomolecular entities, such as PLNTY and diffuse astrocytoma, MYB or MYBL1 altered.

The cognitive functions and seizure outcomes of patients with low-grade epilepsy-associated neuroepithelial tumors

PURPOSE

The aim of the study was to evaluate the cognitive functions and seizure outcomes of patients with low-grade epilepsy-associated neuroepithelial tumors (LEATs).

METHODS

We retrospectively reviewed the clinical data of patients who underwent preoperative neuropsychological evaluations and subsequent epilepsy surgery for LEATs. The neuropsychological results of full-scaled intelligence quotient (FSIQ) and full-scaled memory quotient (FSMQ) were analyzed, as well as the postoperative seizure outcomes.

RESULTS

Of the 138 patients included in the study, 59 patients (40.4%) were female and 47 (36.6%) patients were children. Preoperatively, 138 patients received FSIQ assessments and 30 patients (21.7%) had an intellectual deficit (FSIQ < 80 scores); 124 patients received FSMQ assessments and 32 patients (25.8%) had a memory deficit (FSMQ < 80 scores). Younger age at seizure onset (OR 0.93; P = 0.035) and discordant ictal electroencephalography (EEG) findings (OR 5.26; P = 0.001) were found to predict intellectual deficits, while abnormal hippocampus (OR 2.36; P = 0.051) as well as discordant ictal EEG findings (OR 4.03; P = 0.007) tended to cause memory deficits. During postoperative follow-up, 123 patients (90.7%) were followed up at least 12 months, and among them, 105 patients (85.4%) got seizure-free (Engel class I), while 18 patients (14.6%) were not (Engel class II-IV); longer duration of epilepsy (OR 1.01; P < 0.001) and discordant interictal EEG findings (OR 5.91; P = 0.005) were found to be related to poor seizure outcomes in patients with LEATs.

CONCLUSION

Cognitive deficits commonly occur in patients with LEATs, especially in patients with early or childhood seizures. Early surgical intervention, however, could prevent most of patients from repeated seizure onsets and thus cognitive impairments.

Seizure outcomes and prognostic factors in patients with gangliogliomas associated with epilepsy

Introduction

Ganglioglioma (GG) patients often present with seizures. Although most patients can be seizure-free after tumor resection, some still experience seizures. The present study aimed to analyze a group of GGs patients associated with epilepsy and evaluate the seizure outcomes and prognostic factors.

Methods

This retrospective study involved clinical data collected from medical records of patients diagnosed with GG pathologically and underwent surgical resection in Sanbo Brain Hospital, Capital Medical University. The seizure outcomes were evaluated based on the International League Against Epilepsy (ILAE) seizure outcome classification. The prognostic factors were identified according to univariate and multivariate analysis.

Results

A total of 222 patients were included, with a mean age at surgery of 19.19 ± 10.93 years. All patients were followed up at least for one year with a mean follow-up duration of 6.28 ± 3.17 years. At the final follow-up, 174 (78.4%) patients achieved ILAE Class 1 or 2. Univariate and multivariate analyses revealed that the short duration of seizures and gross total resection were significant positive factors for seizure-free. Bilateral interictal or ictal epileptiform discharges in preoperative video-electroencephalogram (VEEG) were related to poor seizure outcomes.

Conclusion

Surgical resection is an effective treatment for patients with epilepsy associated with GGs. The analysis of predictive factors could effectively guide clinical practice and evaluate the prognosis of epilepsy with GG.

Expedited epilepsy surgery prior to drug resistance in children: a frontier worth crossing?

Epilepsy surgery is an established safe and effective treatment for selected candidates with drug-resistant epilepsy. In this opinion piece, we outline the clinical and experimental evidence for selectively considering epilepsy surgery prior to drug resistance. Our rationale for expedited surgery is based on the observations that, 1) a high proportion of patients with lesional epilepsies (e.g. focal cortical dysplasia, epilepsy associated tumours) will progress to drug-resistance, 2) surgical treatment of these lesions, especially in non-eloquent areas of brain, is safe, and 3) earlier surgery may be associated with better seizure outcomes. Potential benefits beyond seizure reduction or elimination include less exposure to anti-seizure medications (ASM), which may lead to improved developmental trajectories in children and optimize long-term neurocognitive outcomes and quality of life. Further, there exists emerging experimental evidence that brain network dysfunction exists at the onset of epilepsy, where continuing dysfunctional activity could exacerbate network perturbations. This in turn could lead to expanded seizure foci and contribution to the comorbidities associated with epilepsy. Taken together, we rationalize that epilepsy surgery, in carefully selected cases, may be considered prior to drug resistance. Lastly, we outline the path forward, including the challenges associated with developing the evidence base and implementing this paradigm into clinical care.

Surgical resection of dysembryoplatic neuroepithelioma tumor associated with epilepsy based on imaging classification

OBJECTIVE

Dysembryoplastic neuroepithelioma tumors (DNETs) are rare glioneuronal tumors usually present with partial epilepsy. We analyzed the surgical curative effect of DNETs based on imaging classification.

METHODS

The clinical, neuroimaging, seizure history, neuropathological data, and other medical records of 21 cases of cerebral hemisphere DNETs were collected and analyzed retrospectively. According to the magnetic resonance imaging (MRI) classification of Chassoux, these cases were divided into 8 cases of type I (thylakoid type), 6 cases of type II (nodular type), and 7 cases of type III (dysplasia). All patients received detailed preoperative evaluation and underwent surgical treatment. We statistically compared the postoperative seizure outcome of different DNET MRI types by Engel classification.

RESULTS

All tumors were surgically removed and pathologically diagnosed as DNETs. The follow-up period was 5-68 months Engel class I outcome was achieved in all type I cases, 3 (50%) type II cases, and 3 (42.9%) type III cases. The postoperative seizure outcome of MRI type I was better than that of type II and III.

CONCLUSION

Based on the MRI classification of DNET by Chassoux, the postoperative epilepsy control of type I is better than that of type II and type III, which may be related to the residual FCD around the tumor of type II and type III. Thus, the MRI classification of DNET can contribute to the preoperative design of the resection plan. Total resection of type I and extended resection of type II, as well as type III, will help to improve the postoperative seizure-free rate in DNET.

Epilepsy surgery for low-grade epilepsy-associated neuroepithelial tumor of temporal lobe: a single-institution experience of 61 patients

Background

Low-grade epilepsy-associated neuroepithelial tumor (LEAT) is highly responsive to surgery in general. The appropriate surgical strategy remains controversial in temporal LEAT. The aim of this study is to analyze the surgical seizure outcome of temporal LEAT, focusing on the aspects of surgical strategy.

Methods

Sixty-one patients from a single epilepsy center with temporal LEAT underwent surgery. The surgical strategy was according to the multidisciplinary presurgical evaluation. Electrocorticogram (ECoG)-assisted resection was utilized. Surgical extent including lesionectomy and extended resection was described in detail. Seizure outcome was classified as satisfactory (Engel class I) and unsatisfactory (Engel classes II–IV).

Results

After a median follow-up of 36.0 (30.0) months, 83.6% of patients achieved satisfactory outcome, including 72.1% with Engel class Ia. There was 39.3% (24/61) of patients with antiepileptic drug (AED) withdrawal. Use of ECoG (χ2 = 0.000, P > 0.1), preresection spike (χ2 = 0.000, P = 0.763), or spike residue (P = 0.545) was not correlated with the seizure outcome. For lateral temporal LEAT, outcome from lesionectomy was comparable to extended resection (χ2 = 0.499, P > 0.1). For mesial temporal LEAT, 94.7% (18/19) of patients who underwent additional hippocampectomy were satisfactory, whereas only 25% (1/4) of patients who underwent lesionectomy were satisfactory (P = 0.009).

Conclusion

Surgical treatment was highly effective for temporal LEAT. ECoG may not influence the seizure outcome. For lateral temporal LEAT, lesionectomy with or without cortectomy was sufficient in most patients. For mesial temporal LEAT, extended resection was recommended.

Neuropsychiatric Symptoms After Brain Tumor Resection in Children and Adolescents: A Scoping Review

BACKGROUND

Brain tumors are one of the most common solid tumors in pediatric populations, with their treatments having significant neuropsychiatric impact.

OBJECTIVE

The objective of this study was to review the literature on neuropsychiatric sequelae after surgical resection of brain tumors in children and adolescents.

METHODS

Using a scoping method, we reviewed empirical articles describing pediatric patients with brain tumors who underwent partial or total resection and examined major neuropsychiatric domains postoperatively over time.

RESULTS

The initial search yielded 15,543 articles. After duplicate removal, abstract screening, and review, 44 articles were included. Cognitive deficits were the most widely studied outcomes and found to be associated with tumor location, operative variables, perioperative complications, treatment types, and psychosocial factors. Cerebellar mutism, or posterior fossa syndrome, commonly co-occurred with emotional and behavioral dysregulation after posterior fossa resections. Depression, anxiety, and somatization were frequently grouped together as "distress," with higher rates among pediatric patients with brain tumor than among healthy peers. Problematic school behaviors, antisocial, and attention-deficit traits were increased; however, several other behaviors (e.g., risky sexual behaviors, substance use) were equal or lower when compared to peers. Posttraumatic stress disorder was highly prevalent and often interfered with social functioning. Delirium, eating disorders, and longer-term outcomes received inadequate attention.

CONCLUSION

Identifying risk factors of neuropsychiatric sequelae and their impact after pediatric brain tumor resection is important for prognostication and the development of tailored management strategies for these children and adolescents.

Clinical characteristics of low-grade tumor-related epilepsy and its predictors for surgical outcome

Objectives

Low‐grade tumors are the most common neoplasms inducing focal epilepsy; however, the short‐ and medium‐term efficacy of surgery in epilepsy patients with low‐grade tumors remains underappreciated. This study aims to summarize the clinical characteristics of epilepsy patients with low‐grade tumors and to identify factors associated with postsurgical seizure‐free outcomes.

Methods

We retrospectively reviewed consecutive patients with low‐grade tumors who underwent subsequent epilepsy surgery in our epilepsy center, between 2012 and 2018 with a minimum follow‐up of 1 year. Using Engel’s classification and Kaplan–Meier survival analysis, we assessed postoperative seizure freedom over time. Demographical, electroclinical, and other presurgical evaluations were then evaluated for association with postoperative seizure outcome.

Results

The cohort included a total of 132 patients: 79 males and 53 females. Among them, 110 (83.33%) were seizure‐free through their last follow‐up. The Engel class I outcomes were 90.15%, 87.76%, 85.53%, 82.46%, and 73.17% at the end of the 1st, 2nd, 3rd, 4th, and 5th postoperative years, respectively. Multivariate logistic analysis revealed that longer epilepsy duration (p < 0.001, OR 1.091, 95% CI 1.040–1.144) and incomplete resection (p = 0.009, OR 3.673, 95% CI 1.393–9.684) were independently associated with seizure recurrence through the last follow‐up.

Conclusions

Surgical treatment for seizure control in patients with low‐grade tumors provides excellent short‐ and median‐term outcomes.

Can we use intraoperative high-frequency oscillations to guide tumor-related epilepsy surgery?

Objective

In people with low‐grade intrinsic brain tumors, an epileptic focus is often located close to the lesion. High‐frequency oscillations (HFOs) in electrocorticography (ECoG) might help to delineate this focus. We investigated the relationship between HFOs and low‐grade brain tumors and their potential value for tumor‐related epilepsy surgery.

Methods

We analyzed pre‐ and postresection intraoperative ECoG in 41 patients with refractory epilepsy and a low‐grade lesion. Electrodes were designated as overlying the tumor, adjacent resected tissue (peritumoral), or outside the resection bed using magnetic resonance imaging (MRI) and intraoperative photographs. We then used a semiautomated approach to detect HFOs as either ripples (80–250 Hz) or fast ripples (250–500 Hz).

Results

The rate of fast ripples was higher in electrodes covering tumor and peritumoral tissue than outside the resection (p = .04). Mesiotemporal tumors showed more ripples (p = .002), but not more fast ripples (p = .07), than superficial tumors. Rates of fast ripples were higher in glioma and extraventricular neurocytoma than in ganglioglioma or dysembryoplastic neuroepithelial tumor (DNET). The rate of ripples and fast ripples in postresection ECoG was not higher in patients with residual tumor tissue on MRI than those without. The rate of ripples in postresection ECoG was higher in patients with good than bad seizure outcome (p = .03). Fast ripples outside the resection and in post‐ECoG seem related to seizure recurrence.

Significance

Fast ripples in intraoperative ECoG can be used to help guide resection in tumor‐related epilepsy surgery. Preresection fast ripples occur predominantly in epileptogenic tumor and peritumoral tissue. Fast ripple rates are higher in glioma and extraventricular neurocytoma than in ganglioglioma and DNET.

Early Onset Epilepsy Caused by Low-Grade Epilepsy-Associated Tumors and Focal Meningeal Involvement

Background: Low-grade epilepsy-associated neuroepithelial tumors (LEATs) are a frequent etiology in pediatric patients with epilepsy undergoing surgery. Objective: To identify differences in clinical and post-surgical follow-up between patients with focal meningeal involvement (MI) and those without MI within our cohort of pediatric patients with LEATs. Methods: We retrospectively reviewed all pediatric patients (<18 y) who underwent epilepsy surgery between 2011 and 2017 at our hospital. Cohort inclusion required histological diagnosis of LEATs and post-surgical follow-up of ≥2 y. We subsequently stratified patients according to presence of neuroradiological MI. Results: We identified 37 patients: five with MI and 32 without. Half of patients (19) were drug sensitive at surgery; similar between groups. The group with MI differed mainly for age of epilepsy-onset (0.6 vs. 7.0 y) but not for epilepsy duration (0.9 vs. 1.5 y). Post-surgery radiological follow-up (median 4.0 y; IQR 2.8–5.0 y) did not indicate disease progression. Seizure outcome was excellent in both groups, with 34 patients overall being both drug- and seizure-free. Conclusions: Our study identified a new subgroup of LEATs with focal MI and excellent post-surgical outcome. Moreover, this highlights the effectiveness of early surgery in pediatric LEATs.

A methodological perspective on the cognitive outcome of epilepsy surgery in children and adolescents

PURPOSE

The purpose of the study was to explore the impact of timing and test specificity of cognitive outcome measures after pediatric epilepsy surgery.

METHODS

A consecutive national cohort of 114 children with medically resistant epilepsy having had resective epilepsy surgery were screened for children tested with a complete age-appropriate Wechsler Intelligence test at two or three time-points. This provided 43 children for analyses. Composite subscale scores were assessed in comparison to index and intelligence quotient (IQ) scores.

RESULTS

We found a main effect of time in seizure-free children for full-scale IQ (FSIQ); F(2, 42) = 6.49 with higher T2 measures compared with T1 (M_Diff = 5.46, p = .006). There was a difference in FSIQ scores between seizure-free and nonseizure-free children at T2; M = 7.31, 95% confidence interval (CI) [0.05 to 14.57], t(38) = 2.04, p = .049, favoring seizure-free children. A statistical difference between composite scale scores and index scores was found with medium to large effect. The correlation of medical treatment (anti-epileptic drug (AED)) change and score differences in FSIQ outcome was significant (p = .041), with less AED correlated with a higher FSIQ. All children with left-temporal surgery had a stable or improved verbal comprehension composite subscale score outcome at T2 regardless of seizure status.

CONCLUSION

Our results correspond to some longitudinal studies with outcome measures >2 years, in contrast to short-term studies ≤2 years with a stable outcome. Our study supports the fact that the specificity of the used tests and the timing of assessments after pediatric epilepsy surgery are essential factors for the clinical validity of outcome measures. However, there are further needs of extensive longitudinal studies to provide a better understanding of life-long cognitive development and impact after childhood epilepsy surgery.

Factors associated with seizure and cognitive outcomes after epilepsy surgery for low-grade epilepsy-associated neuroepithelial tumors in children

Low-grade epilepsy-associated neuroepithelial tumors (LEATs) are responsible for drug-resistant chronic focal epilepsy, and are the second-most common reason for epilepsy surgery in children. LEATs are extremely responsive to surgical treatment, and therefore epilepsy surgery should be considered as a treatment option for LEATs. However, the optimal time for surgery remains controversial, and surgeries are often delayed. In this review, we reviewed published article on the factors associated with seizure and cognitive outcomes after epilepsy surgery for LEATs in children to help clinicians in their decision whether to pursue epilepsy surgery for LEATs. The achievement of gross total resection may be the most important prognostic factor for seizure freedom. A shorter duration of epilepsy, a younger age at surgery, and extended resection of temporal lobe tumors have also been suggested as favorable prognostic factors in terms of seizure control. Poor cognitive function in children with LEATs is associated with a longer duration of epilepsy and a younger age at seizure onset.

[Surgical treatment of epilepsy in children with gloneuronal brain tumors: morphology, MRI semiology and factors affecting the outcome]

INTRODUCTION

Glioneuronal tumors (GNT) are usually found in children (less than 1.5% of all neoplasms of the brain). With rare exceptions, they are benign and usually manifest only by epilepsy, which is quite often resistant to treatment with AE drugs. Tumor removal usually helps to cope with epileptic seizures, however, a number of issues regarding diagnosis and surgical treatment (interpretation of morphological data and classification, epileptogenesis and topography of the epileptogenic zone, the value of intraoperative invasive EEG and the optimal volume of resection) remain debatable.

AIM

To describe the morphology, electro-clinical picture and MR-semiology in patients with gloneuronal brain tumors, as well as to analyse the results of their surgical treatment and the factors determining its outcome.

MATERIAL AND METHODS

152 children with a median age of 8 years were treated surgically (There were 64 gangliogliomas, 73 DNT, 15 cases where the tumor classification failed - GNT NOS). In children under 2 years of age, temporal localization of the tumor prevailed. In 81 cases, ECoG was used during the operation. Surgical treatment complications: transient neurological deficit (in 15 cases); hematomas removed without consequences (in 2 cases), infectious (osteomyelitis of bone bone flap in 2 cases). We analyzed: the age of the epilepsy onset (median - 4 years 7 months) and its duration (median - 23.5 months), the type of seizures, as well as the features of MR-semiology and morphology of tumors and adjacent areas of the brain. The volume of tumor resection was verified by MRI (in 101 cases) and CT (in each case). The follow-up was collected through face-to-face meetings, with repeated video EEG and MRI, as well as telephone interviews. We studied the effect of a number of parameters characterizing the patient and features of his/her operation on the outcome of treatmen.

RESULTS

Among 102 patients in whom the follow-up history is one year or more (median - 2 years), a favorable outcome (Engel IA) was observed in 86 of them (84%); 55 of them (54%) at the time of the last examination stopped drug AE treatment. Radical tumor removal and younger age at the time of surgery were statistically significantly associated with a favorable result.

CONCLUSION

In children with gloneuronal brain tumors, removal of the tumor is effective and relatively safe in the treatment of symptomatic epilepsy. Radical tumor resection and earlier intervention are the most important prerequisites for a favorable outcome and persistent remission of seizures.

Measure thrice, cut twice: On the benefit of reoperation for failed pediatric epilepsy surgery

OBJECTIVE

To determine whether clinical outcomes are improved after repeat surgery for medically refractory epilepsy in children.

METHODS

This is a single-center retrospective cohort analysis of all patients who received repeat resective surgery for ongoing seizures from 2000-2017. From a total of 251 consecutive individual epilepsy surgical patients for focal resection, 53 patients met study inclusion criteria and had adequate follow-up documented.

RESULTS

Median age of seizure-onset was 2.0-years-old (IQR 0.3-5.5 years). The median age at first epilepsy surgery was 6.3-years-old (IQR 2.9-9.2 years) and at second epilepsy surgery was 8.4-years-old (IQR 4.7-12.6 years). Overall, 53 % (n = 28) of this series achieved Engel Class I (seizure freedom); with improved seizure control (Engel Class I-II) in 83 % (n = 44) of the cohort. 64 % (n = 34) had one reoperation; 26 % (n = 14) had two; and 9% (n = 5) had three. Pathology: 58 % (n = 31) had focal cortical dysplasia; 13 % (n = 10) tumor; 9% (n = 5) encephalitis; 6% (n = 3) gliosis; 4% (n = 2) mesial temporal sclerosis; and 2% (n = 1) hemimegalencephaly. Tumor pathology was associated with increased chance (p = 0.01) for seizure freedom (90 % of tumor patients had Engel Class I outcome). MTS had worse outcome with both patients having ongoing seizures (Engel II-IV). There were 6 patients who developed post-operative hemiparesis; one was unplanned but resolved.

SIGNIFICANCE

Reoperation for pediatric epilepsy surgery can lead to seizure freedom in many cases and improved seizure control in most cases. Reoperation for brain tumor pathology is associated with a high rate of seizure freedom.

Somatostatin receptor expression and mTOR pathway activation in glioneuronal tumours of childhood

PURPOSE

To investigate the expression of somatostatin receptors (SSTRs) and markers of mTOR pathway in paediatric glioneuronal tumours and correlate these findings with tumour type, BRAFV600E mutational status and clinical characteristics such as tumour location, seizure frequency and duration, and age.

METHOD

37 children and adolescents with a neuropathological diagnosis of glioneuronal tumour were identified over a 22-year period. Immunohistochemical analyses for SSTRs type 1, 2A, 3, 5 and ezrin-radixin-moesin (ERM) and phosphorylated S6 (pS6), which are indicators of mTOR pathway activation, were performed in tumour specimens from 33 patients and evaluated using the immunoreactive score (IRS). The IRS were compared to tumour type, BRAFV600E status and clinical characteristics.

RESULTS

Ganglioglioma (GG) was the most frequently encountered subgroup (n = 27), followed by dysembryoplastic neuroepithelial tumour (DNET; n = 4). GGs expressed SSTR2A and SSTR3 to a high extent, 56 % and 44 % respectively. Expression of SSTR2A was also found in DNETs. Signs of mTOR pathway activation were abundant in GGs, but only present in one DNET. No correlations with BRAFV600E presence or clinical characteristics were found.

CONCLUSIONS

Expression of SSTRs and activation of mTOR pathway in paediatric glioneuronal tumour suggest that somatostatin analogues and mTOR inhibitors may have potential therapeutic implications in a subset of inoperable childhood glioneuronal tumours causing medically refractory epilepsy and/or tumour growth. Further clinical studies are warranted to validate these findings.

Epilepsy outcome following resection of low-grade brain tumors in children

OBJECTIVE

The indication for and timing of surgery for epilepsy associated with low-grade mixed neuronal-glial tumors may be controversial. The purpose of this study was to evaluate the effect of resection and associated variables on epilepsy and on progression-free survival (PFS).

METHODS

A retrospective chart review of patients treated between 1992 and 2016 was conducted to identify individuals with epilepsy and low-grade gliomas or neuronal-glial tumors who underwent resective surgery. Data analyzed included age at epilepsy onset, age at surgery, extent of resection, use of electrocorticography, the number of antiepileptic drugs (AEDs) before and after surgery, the presence of dysplasia, Engel class, histological findings, and PFS. The institutional review board protocol was specifically approved to conduct this study.

RESULTS

A total of 107 patients were identified. The median follow-up was 4.9 years. The most common pathology was dysembryoplastic neuroepithelial tumor (36.4%), followed by ganglioglioma (31.8%). Eighty-four percent of patients had Engel class I outcomes following surgery. Gross-total resection was associated with a higher likelihood of an Engel class I outcome (90%) as compared to subtotal resection (58%) (p = 0.0005). Surgery reduced the AED burden, with 40% of patients requiring no AEDs after surgery (p < 0.0001). Children with neurodevelopmental comorbidities (n = 5) uniformly did not experience seizure improvement following resection (0% vs 83% overall; p < 0.0001). Electrocorticography was used in 33% of cases and did not significantly increase class I outcomes. PFS was 90% at 5 years. Eleven percent of tumors recurred, with subtotal resection more likely to result in recurrence (hazard ratio 5.3, p = 0.02). Histological subtype showed no significant impact on recurrence.

CONCLUSIONS

Gross-total resection was strongly associated with Engel class I outcome and longer PFS. Further studies are needed to elucidate the suitable time for surgery and to identify factors associated with oncological transformation.

Epilepsy Surgery for Children With Low-Grade Epilepsy-Associated Tumors: Factors Associated With Seizure Recurrence and Cognitive Function

OBJECTIVE

Low-grade epilepsy-associated tumors (LEATs) are associated with childhood seizures that are typically drug-resistant, necessitating surgical interventions. In this study, we aimed to investigate the efficacy of surgical intervention in children with LEATs and to identify factors associated with seizure and cognitive outcomes.

METHODS

We reviewed 58 children less than 18 years of age who underwent epilepsy surgery due to histopathologically confirmed LEATs and had a minimum postoperative follow-up duration of 24 months.

RESULTS

Of the 58 patients who were followed for a median duration of 5.6 (IQR 3.2 to 10.0) years, 51 (87.9%) were seizure-free after surgery. In univariate analysis, shorter epilepsy duration, fewer antiepileptic drugs at time of surgery, gross total resection, and unilobar tumor involvement were associated with seizure freedom. In multivariate analysis, gross total resection was independently associated with seizure freedom. The preoperative and postoperative full-scale intelligence quotient (FSIQ) scores were 78.9 ± 27.1 and 80.9 ± 28.7, respectively. In univariate analysis, younger age at seizure onset, longer epilepsy duration, more antiepileptic drugs at time of surgery, multilobar tumor involvement, and presence of generalized epileptic discharges were associated with lower preoperative FSIQ. In multivariate analysis, longer epilepsy duration was independently associated with lower preoperative FSIQ scores. Postoperative FSIQ scores were significantly influenced by preoperative FSIQ scores.

CONCLUSIONS

Epilepsy surgery for LEATs in children resulted in excellent seizure outcome. Gross total resection was the only independent factor associated with favorable seizure outcome. Preoperative and postoperative cognitive abilities were significantly influenced by epilepsy duration, so early surgical intervention should be considered.

MicroRNA519d and microRNA4758 can identify gangliogliomas from dysembryoplastic neuroepithelial tumours and astrocytomas

Glioneuronal tumours, including gangliogliomas and dysembryoplastic neuroepithelial tumours, represent the most common low-grade epilepsy-associated brain tumours and are a well-recognized cause of intractable focal epilepsy in children and young adults. Classification is predominantly based on histological features, which is difficult due to the broad histological spectrum of these tumours. The aim of the present study was to find molecular markers that can be used to identify entities within the histopathology spectrum of glioneuronal tumours. The focus of this study was on microRNAs (miRNAs). miRNAs are important post-transcriptional regulators of gene expression and are involved in the pathogenesis of different neurological diseases and oncogenesis. Using a miRNA array, miR-519d and miR-4758 were found to be upregulated in gangliogliomas (n=26) compared to control cortex (n=17), peritumoural tissue (n=7), dysembryoplastic neuroepithelial tumours (n=9) and astrocytomas (grade I-IV; subependymal giant cell astrocytomas, n=10; pilocytic astrocytoma, n=15; diffuse astrocytoma grade II, n=10; grade III, n=14 and glioblastoma n=15). Furthermore, the PI3K/AKT3/P21 pathway, which is predicated to be targeted by miR-519d and miR-4758, was deregulated in gangliogliomas. Functionally, overexpression of miR-519d in an astrocytic cell line resulted in a downregulation of CDKN1A (P21) and an increase in cell proliferation, whereas co-transfection with miR-4758 counteracted this effect. These results suggest that miR-519d and miR-4758 might work in concert as regulators of the cell cycle in low grade gliomas. Furthermore, these miRNAs could be used to distinguish gangliogliomas from dysembryoplastic neuroepithelial tumours and other low and high grade gliomas and may lead to more targeted therapy.

Surgical treatment for refractory epilepsy

The goal of any epilepsy surgery is to improve patient's quality of life by achieving seizure freedom or by reducing the frequency of severely debilitating seizures. To achieve this goal, non-invasive and invasive diagnostic methods must precisely delineate the epileptogenic zone (EZ), which is defined as the area that needs to be resected to obtain seizure freedom. At the same time, the correct identification of eloquent brain areas is inevitable to avoid new neurological deficits from surgery. In recent years, the technical advances in diagnostics have enabled us to achieve these goals in an increasing number of cases. As a consequence, and with new surgical treatment options available, the number of patients who might benefit from epilepsy surgery is constantly increasing. Especially in pediatric epilepsy, early surgical intervention is becoming frequently advocated as it has been shown to improve cognitive and behavioral outcome. Specialized epilepsy centers and multidisciplinary teams are required to provide adequate care and treatment. The goal of this review is to describe important diseases that are accessible to epilepsy surgery and to give an overview of current diagnostic methods. The focus lies on established as well as novel techniques in epilepsy surgery. The presurgical work-up and patient selection is outlined.